JPH0446583A - Detecting method stop position of rotor in brushless dc motor having no position transducer - Google Patents

Abstract

PURPOSE:To reduce power consumption by detecting the relative position of the position of the magnetic pole of a rotor and a three-phase winding by a conductive pattern, from which a measured voltage value is obtained. CONSTITUTION:Conduction at 180 deg. to star-connected three-phase windings U, V, W is made conductive successively by each of six kinds of conductive patterns. Consequently, the relative positional relationship of the positions of magnetic poles formed by magnetization to a rotor 30 under the state of stoppage and the locations of three-phase windings U, V, W can be determined according to the states of six neutral-point voltage values at the transient time measured discretely at a neutral point Pcom in response to conduction by six kinds of the conductive patterns. That is, a control signal is transmitted over a commutation control circuit 4 from a controller 1, and the commutation control circuit 4 is operated so that conduction at 180 deg. to the three-phase windings U, V, W is performed successively to each of six kinds of the conductive patterns at every predetermined short time set to a timer 3.

Description

[Detailed description of the invention] [Industrial application field]

The method of detecting the stop position of the rotor of a brushless DC motor without a position detector according to the present invention is applicable to small, thin, low cost, low power consumption, and high efficiency motors such as small fixed disk devices, small VTRs, etc. Widely used in equipment or equipment that requires

[Conventional technology]

In a brushless DC motor, in order to sequentially switch and supply drive current to the motor windings of each phase at a predetermined commutation timing, the motor windings are connected to the excitation magnetic poles. A signal indicating the positional information of the rotor (signal indicating the rotational phase information of the rotor) indicating the relative positional relationship is required. Conventionally, brushless DC motors detect the rotational phase information of their rotor using a position detector that includes, for example, a Hall element or an optical element.
A switching control signal having a predetermined commutation operation timing generated based on a signal indicating rotational phase information of the rotor output from the position detector is applied to an electronic switching element such as a transistor. , drive current is supplied sequentially to multiple motor windings, or the back electromotive force generated in each motor winding during the rotation of one rotor is reversed, which occurs in the motor windings of at least two phases. A signal indicating the rotational phase information of the rotor is generated from the electromotive voltage, and a switching control signal having a predetermined commutation operation timing generated based on the signal is applied to an electronic switching element such as a transistor. , drive current is sequentially supplied to the plurality of motor windings. The brushless DC motor of the latter configuration described above, that is, the brushless DC motor that does not have a one-position detector,
Since the position detector required in the brushless DC motor of the former configuration described above is not required, the configuration of the motor can be simplified, and there are no problems caused by the low reliability of the position detector itself. Furthermore, mounting the position detector in a predetermined position has the advantage that there is no difficulty in assembling and manufacturing to accurately mount the position sensor, and this is particularly advantageous when constructing a small brushless DC motor. By the way, when starting the motor, it is necessary to control the commutation of the windings of each phase so that the stopped rotor can start rotating in a predetermined rotation direction. Since a brushless DC motor that does not have a position detector is not equipped with a position detector, in order to sequentially supply drive current to the windings of each phase in the desired commutation mode at the time of startup, The relative position of the rotor's magnetic poles and windings when stopped is detected, and each phase is adjusted so that the rotor starts rotating in the desired rotation direction based on the detected relative position of the rotor's magnetic poles and windings. The commutation must be controlled. Then, by selectively supplying current in one or both directions to the other end of the winding of each phase in the three-phase winding in which one end of the winding of each phase is commonly connected, a predetermined connection is achieved. Conventionally, in order to detect the stop position of a rotor in a brushless DC motor that does not have a position detector, a freely rotatable rotor with a plurality of magnetic poles formed by a magnetic pattern is rotationally driven. When the three-phase winding is energized at an electrical angle of 180 degrees, each of the three-phase windings is sequentially energized at an electrical angle of 180 degrees using each individual energization pattern of all types of energization patterns. Detection means for detecting the stop position of the rotor, which detects the rotor stop position based on the measurement result of the voltage generated when the current flowing through the windings of each phase is passed through one current detection resistor. is disclosed in Japanese Patent Application Laid-Open No. 63-69489. (Problem to be Solved by the Invention) However, in the conventional rotor stop position detection means described above, the current of the winding of each phase is passed through the current detection resistor, and the voltage generated in the current detection resistor is measured. Therefore, when the motor generates maximum torque, a large amount of power is consumed by the current detection resistor described above. For example, if the motor drive power source is 12 volts, the current detection resistor described above is Usually, a resistor of about 1 ohm is used, and for example, if the driving power source of the motor is 5 volts, a resistor of about 0.68 ohm is usually used as the current detection resistor. In either case, when the motor generates maximum torque, approximately 10% of the power is wasted due to the current detection resistor described above. Needless to say, this is a serious problem for devices that use batteries as a power source, and for example, in fixed disk drives (hard disk drives), the motor drive current is 1.
Generally, a current of about ampere is passed through the resistor, but in such cases, the resistor generates a lot of heat, so it is necessary to use a metal film resistor with a high power resistance of about 1 watt. For this reason, when chip components are used in a small device, the current detection resistor can be made into a chip.Therefore, the rotor stop position detection means configured to use the above-mentioned current detection resistor can be used. If adopted, there would be problems in terms of shape, implementation, and cost. Furthermore, in the case where the voltage generated in the current detection resistor is measured by an analog-to-digital converter (hereinafter, analog-to-digital conversion may be referred to as AD conversion), as described above, , the above-mentioned AD
If we consider the case where an 8-bit converter, which is commonly used as a converter, is used with a 5-volt power supply, in this case, 1 bit will be 19 millivolts, but the current detection resistor that produces the voltage to be measured will In order to reduce power consumption, if the resistance value is set to about 1 ohm, for example, the actual side chamber voltage range that can be detected will be a few bits, so it is sufficient to consider the possibility of noise incorporation. high resolution cannot be obtained. Furthermore, in the conventional example described above, when the rotor is stopped and the three-phase winding is energized in an electrical angle of 180 degrees, each individual energization of all types of energization patterns is performed. Based on the measurement results of the voltage generated when the windings of three phases are sequentially energized in a pattern at an electrical angle of 180 degrees, and the current flowing through the windings of each phase is passed through one current detection resistor. When detecting the voltage, we make sure to measure the voltage for all types of energization patterns when the three-phase winding is energized in an electrical angle of 180 degrees. Another problem is that the torque generation efficiency is poor. This occurs when detecting the voltage generated in one current detection resistor through which the current of each phase winding is passed, such as in a brushless DC motor without a position detector disclosed in Japanese Patent Application Laid-Open No. 63-69489. The problems mentioned above are such that when the rotor is rotating, the back electromotive force induced in the winding of a phase that is not energized is detected from the end of the winding of that phase, and the rotational phase of the rotor is determined. Measurement of the voltage at the end of the winding in the case of a rotational phase detection means for a brushless DC motor without a position detector, which is used as a signal containing information 1, for example, as described in Japanese Patent Publication No. 61-3193. I think that the problem can be solved by using a similar method, that is, by detecting the voltage induced in the winding of a phase that is not energized when the rotor is stopped from the end of the winding of that phase. However, if the solution described above is adopted, the following new problems arise. FIGS. 12 to 14 are diagrams for explaining the above-mentioned newly occurring problems. Figure 12 shows the three-phase windings U, V, and
It is a diagram showing a state in which W is star-connected, and one end of each phase winding U, V, W is a common connection point P c
They are commonly connected at om. a, b, and c indicate the other ends of the windings U, V, and W of each phase described above. Now, when one rotor is in a stopped state, the combination of two windings in each of the three-phase windings U, V, and W shown in Fig. 12 is changed, and current is sequentially passed through the windings. If we measure the voltage appearing at the end of the winding of the phase that is not connected, we will obtain the measurement result as shown in FIG. 13, for example. In Figure 13, C→b in the frame shown at the bottom of the figure
, a→c, b→a, Q→a, etc. are the periods during which current flows from the terminal C of the W-phase winding W to the terminal of the U-phase winding U; Winding W of W phase from terminal a of wire V
The period when current is being applied so that the current flows through the terminal C of the U-phase winding U, the period when the current is being applied so that the terminal A of the phase winding V is being energized from the terminal of the U-phase winding U, The curves shown in the upper part of FIG. As an example of the state of the voltage that appears in the section, the state of change in voltage that has been measured at the end of the U-phase winding during each of the energization periods described above is shown.
Figure 13 shows that with the rotor in a stopped state, the combinations of two windings in the three-phase windings U, V, and W shown in Figure 12 are changed, and the two windings are sequentially changed. To pass current,
(This is an example of voltage measurement results when using a power supply voltage of 5 volts) is the winding end a, Q of the other phase.
Also the appearance of voltage changes. Needless to say, the mode of voltage change is similar to that illustrated in FIG. 13. As is clear from the curve of the voltage measurement results at the ends of the windings illustrated in Figure 13, one current was applied to the ends of the windings of each phase when the mode of energization for one winding was switched. The release of the magnetic energy LI''/2 stored in the windings results in an extremely high voltage, as is well known. Normally, the voltage value is, for example, 10 volts or more.Therefore, conventionally, in order to prevent the commutation switch transistors Ql-Q6 from being destroyed due to the high voltage generated in the windings due to the above-mentioned causes, a As shown by the dotted line in Figure 14, diodes di and d2 are connected between each winding to protect the commutation switch transistors Ql-Q6. When protective diodes di, d2 are connected to
2, each winding is clamped to a specific potential (power supply voltage or ground potential), so even if the voltage at the end of one winding is measured, it is not possible to obtain a voltage value that includes the desired information. Therefore, without connecting the protective diodes di and d2,
As mentioned above, when trying to measure a high voltage of 10 volts or more using a 5 volt circuit, for example, use a resistor network etc. to ensure that the voltage to be measured is within the range of the power supply voltage. measurement is required. In addition, when the voltage induced in the winding of a phase that is not energized when the rotor is in a stopped state is detected from the end of the winding of that phase as described above, each It is necessary to provide separate measuring circuits at the ends of the phase windings, making the construction complex and expensive.

[Means for Solving the Problems] The present invention provides a three-phase winding in which one end of the winding of each phase is commonly connected, and current in both directions is selectively transmitted to the other end of the winding of each phase. Detects the stopped position of the rotor in a brushless DC motor that does not have a position detector. In the case where the three-phase main wire is energized in an electrical angle of 180 degrees, the three-phase windings are sequentially energized in each individual conduction pattern of all types of energization patterns at an electrical angle of 180 degrees. A means for applying current when the rotor is stopped in an energized state, magnetic flux passing through individual magnetic paths of each phase winding due to the current flowing individually to each phase winding during energization, and rotation. Corresponding to the change in inductance that occurs in the windings of each phase due to the magnetic flux that is the vector sum of the magnetic flux that passes through each of the individual magnetic paths described above due to the child magnetic poles, each of the common connecting ends of the three-phase windings described above A voltage measuring means for measuring the voltage generated as a ratio of the impedance of the phase windings, and a voltage measuring means for measuring the voltage generated as a ratio of the impedance of the phase windings, and a method for determining the position of the magnetic poles of the rotor and the three-phase windings based on the voltage values individually measured for each of the above-mentioned individual energization patterns. A method for detecting the stop position of a rotor in a brushless DC motor without a position detector, which consists of a means for detecting relative position, and a method for energizing three-phase windings in an energizing mode of 180 electrical degrees. The voltage values individually measured at the common connection end of the 3-phase winding during energization with each individual energization pattern of all types of energization patterns are applied to the common connection end of the 3-phase winding. 1/3 of the power supply voltage that appears when
A first group of measured voltage values showing a measured voltage value close to the voltage value of 'Measurement voltage value groups', find the difference voltage between the minimum voltage value and the maximum voltage value in absolute value for each measurement voltage value group described above, and calculate the difference voltage found for each of the abovementioned groups. Stopping the rotor in a brushless DC motor without a position detector, which detects the relative position of the rotor's magnetic poles and three-phase windings using a current conduction pattern that yields a relatively large voltage difference. By using the position detection method and at least one energization pattern among all types of energization patterns when energization is carried out in a 180-degree electrical angle to the 3-phase winding, 3-phase windings are detected when the rotor is stopped. A means for energizing the phase windings, a magnetic flux that passes through the individual magnetic paths of each phase winding due to the current flowing individually through the windings of each phase when energized as described above, and each individual individual described above due to the magnetic poles of the rotor. Corresponding to the change in inductance that occurs in the winding of each phase due to the magnetic flux that is the vector sum of the magnetic flux passing through the magnetic path of
Voltage measuring means for measuring a voltage generated at a common connection end of the phase windings as a ratio of impedances of the windings of each phase;
The voltage value individually measured at the common connection end of the three-phase winding during energization in each of the above-mentioned individual conduction patterns is calculated as 1/3 of the power supply voltage that appears at the common connection end of the three-phase winding in a steady state. A first set of measured voltage values showing a measured voltage value close to the voltage value, and a second set of measured voltage values showing a measured voltage value close to 2/3 of the power supply voltage that appears at the common connection end of the three-phase winding in a steady state. For each measured voltage value group described above, voltage measurement is performed for one energization pattern, and then energization is performed in sequentially different energization patterns for each measurement voltage group. When the measured voltage value is measured. If the measured voltage value obtained previously has a voltage value larger than the predetermined voltage value, the position of the magnetic poles of the rotor and the three-phase winding will be determined depending on the energization pattern from which the chamber voltage value was obtained. A method for detecting the stopped position of a rotor in a brushless DC motor that does not have a position detector that detects the position relative to the wire, and energizing the three-phase windings in a 180-degree electrical angle manner. Means for energizing three-phase windings when the rotor is stopped by at least one energization pattern among all types of energization patterns when energization is carried out; The inductance generated in the windings of each phase is calculated by the vector sum of the magnetic flux passing through the individual magnetic paths of each winding of each phase and the magnetic flux passing through the above-mentioned individual magnetic paths due to the magnetic poles of the rotor. In response to the change, the above-mentioned 3
Voltage measuring means for measuring a voltage generated at a common connection end of the phase windings as a ratio of impedances of the windings of each phase;
3 when energizing with each of the individual energizing patterns described above.
The voltage values individually measured at the common connection ends of the phase windings are replaced by a first voltage value that is close to 1/3 of the power supply voltage that appears at the common connection ends of the three-phase windings in a steady state.
Each of the measurements described above is divided into a group of measured voltage values and a second group of measured voltage values that are close to the voltage value of 273 of the power supply voltage that appears at the common connection end of the three-phase winding in a steady state. Voltage measurements are performed on the energization patterns sequentially for each voltage value group, and the measured voltage values measured during energization in sequentially different energization patterns for each measurement voltage group are calculated as three-phase windings for each measurement value group. Steady-state special code at the common connection end of the line: If a measured voltage that has a difference of more than a predetermined voltage value compared to the voltage value that appears in the steady state is obtained, that measured voltage value has been obtained. A method for detecting the stop position of a rotor in a brushless DC motor without a position detector is provided, which detects the relative position of the rotor's magnetic poles and three-phase windings based on an energization pattern. (Function 1) Currents in both directions are selectively supplied to the other end of each phase winding in a three-phase winding in which one end of each phase winding is commonly connected. A freely rotatable rotor, which has multiple magnetic poles formed by a magnetization pattern, is driven to rotate.When the rotor of a brushless DC motor without a position detector is in a stopped state, a voltage is applied to the three-phase windings. When energization is carried out 180 degrees by a power supply with a value of Vcc, the voltage V c that appears at the common connection point Pcom of the star-connected three-phase windings in a steady state
o m (neutral point voltage Vcom) is connected to the outer end of the winding of one phase of the three-phase windings in which the positive terminal of the power supply is star-connected, and the winding of the other two phases. When the negative terminal of the power supply is connected to the outer end of the wire, Vcc/3
or 2Vcc/3 (In a brushless DC motor that does not have an actual position sensor, current flows through the commutation switch transistors connected in series to the three-phase windings, so the rotor stops. When the 3-phase windings are energized 180 degrees by a power source with a voltage value of Vcc while the 3-phase windings are in the state of The neutral point voltage V com has a voltage value different from the voltage value described above by the slight voltage drop caused by the transistor described above. This is because the influence of the inductance L of the windings of each phase can be ignored in a steady state when the three-phase windings are energized 180 degrees from the DC voltage Vcc power source while the rotor is stopped. be. By the way, since the three-phase winding in a brushless DC motor without a position sensor is wound around a core 43 made of ferromagnetic material as shown in FIGS. 3 and 4,
The inductance value of each of the three-phase windings U, V, and W changes because the amount of magnetic flux that passes through the portion of the core around which each winding is wound changes the magnetic permeability of that portion. 4 and 5 show the relative positional relationship between the magnetic pole positions magnetized on the rotor 30 and the positions of the three-phase windings U, V, and W, and the three-phase windings U, V, and Due to the difference in the pattern of energization flowing through W, the three-phase winding U. 3 is a diagram used to explain that the inductance values of each of (1) and (W) change. In FIG. 4(,) to FIG. 4(d), 43 is a core 43 made of ferromagnetic material around which three-phase windings U, V, and W are wound; a) and FIG. 4(b) show the magnetic poles N, S, N formed by magnetization on the 5-rotor 30.
, S, and the correspondence relationship between the magnetic poles of the rotor 30 and the core 43 around which the three-phase windings U, V, and W are wound are the same, the three-phase windings U, When the mode of energization to V and W is as shown in (a) in Fig. 4, it is as shown in (c) in Fig. 4.
), and in the case of FIG. 4(b), the energizing mode is as shown in FIG. 4(d). In FIG. 4(a) and FIG. 4(b), the arrow φ1~
φ4 is the core 4 around which three-phase windings U, V, and W are wound.
It indicates the direction of the magnetic flux passing through 3, and the magnetic flux φ1
．． For φ2, the three-phase windings U, V, and W are energized in a 180-degree energizing manner as shown in FIG. 4(c) or FIG. 4(d). It shows the magnetic flux generated by the current flowing through the three-phase windings U, V, and W and passing through the core 43 when the magnetic flux φ3. φ4 comes out from the magnetic pole N formed by magnetizing the rotor 30,
It shows the magnetic flux that passes through the core 43 around which three-phase windings U, V, and W are wound and enters the magnetic pole S formed by magnetizing the rotor 30. In addition, in FIG. 4(a) and FIG. 4(b), three-phase windings U, V, and W are wound around the magnetic pole N formed by magnetizing the rotor 30. A magnetic flux φ3. passes through the core 43 and enters the magnetic pole S formed on the rotor 30 by magnetization. The arrow φ3°φ4 indicating φ4 is shown outside the core 43 because of the magnetic flux φ3. Arrow φ3 indicating φ4. φ
This is because if 4 is written inside the core 43, the content of the figure becomes difficult to understand. Now, in a state where the three-phase windings U, V, and W are energized 180 degrees in the manner shown in FIG. 4(c), the aforementioned magnetic flux φl passing through the core 43 is ~
φ4 is the magnetic flux φl as shown in FIG. 4(a)
, the passing direction of φ2 is opposite to the passing direction of magnetic fluxes φ3° and φ4, and in this state, the portion of the core 43 where the phase winding ■ is wound, that is, the three-phase winding U.
The total magnetic flux φl, φ generated by the current flowing through ,V,W
2 passes through, the above-mentioned magnetic flux φ1. φ2
The magnetic flux φ3. Since φ4 (magnetic flux φ3 generated by the magnetic poles formed by magnetizing the passing rotor 30) is passing through, magnetic saturation does not occur. However, for three-phase windings U, V, and W, (d) in Figure 4
In the state where 180 degree energization is carried out in the manner shown in FIG.
~φ4 is the magnetic flux φ as shown in FIG. 4(b)
The passing direction of magnetic fluxes φ3 and φ4 is the same as the passing direction of magnetic fluxes φ3 and φ4, and in this state, the V in the core 43 described above
The part where the phase winding V is wound, that is, the three-phase windings U and V. The total magnetic flux φ1. generated by the current flowing through W. φ2′″
The portion through which the magnetic flux φ1. φ2 and magnetic flux φ3
．． By adding φ4 (magnetic flux φ3 generated by the magnetic poles formed by magnetizing the passing rotor 30), magnetic saturation or a state close to it is achieved. By the way, as can be seen from Figure 5, which illustrates the B-H curve and μ-H curve of a ferromagnetic material, the value of the magnetic permeability μ of the ferromagnetic material indicated by the slope of the B-H curve is determined by the magnetic flux density. Therefore, the magnetic permeability μ of the core 43 in the state of FIG. 4(a) and the state of FIG. 4(b) described above
The values of will naturally be different. Therefore, the value of the inductance L of the three-phase windings U, V, and W wound around the core 43 mentioned above. They will change in accordance with the value of the magnetic permeability μ of the core around which they are wound. The three-phase windings U, V, which are wound around the core 43,
As is clear from the above description of FIGS. 4(a) and 4(b), the change in the value of the inductance L of W, s4R, depends on the magnetic poles magnetized on the rotor 30. The relative positional relationship between the position and the position of the three-phase windings U, V, and W, and the three-phase winding U. They can be identified by the difference in the pattern of the energization applied to v and W, respectively. Therefore, the energization pattern for the three-phase windings mu, V, and W is known, and the three-phase winding U. If the manner of change in inductance in v and W is known, the position of the magnetic poles magnetized on the rotor 30 and the three-phase winding U can be determined.
, V, and W can be determined. As mentioned above, each winding U, V, and W that occurs when the three-phase windings U, V, and W are energized in a 180-degree energization manner.
For example, in the case of Fig. 4 (a), the inductance value of W is large, and the inductance value of the winding U of the U phase and the inductance of the winding W of the W phase are large. value becomes small, and in the case of (b) in Figure 4, ■
The inductance value of the phase winding ■ is small, and the inductance value of the U-phase winding U and the inductance value of the W-phase winding W are large. So, when the rotor 30 in the brushless DC motor is at rest, the three-phase windings U, V. When W is energized at 180 degrees, the voltage Vcom (neutral point voltage Vcom) that appears at the common connection point Pcom of the star-connected three-phase windings is the voltage Vcom (neutral point voltage Vcom) of each phase described above. Windings U, V. The voltage value corresponds to the impedance ratio of W. Now - as an example, the rotor 3 in a brushless DC motor
Star connected when 0 is in the stopped state: 3
When the phase windings U, V, and W are energized in a 180-degree energizing manner, for example, as shown in FIG. 4(c), the three-phase windings U, V,
In W, suppose that the inductance value of the winding U of the tJ phase and the inductance value of the winding W of the W phase are both L, and the inductance value of the winding gv of the ■ phase is (L - ΔL). , Furthermore, the current Iw flowing through the W-phase winding W and the current Iu flowing through the U-phase winding U are equal (the current flowing through the V-phase winding V is (Iu+Iw)=2I u=2Iw)
Then, the voltage Vco appearing during a transient period at the common connection point Pcom of the star-connected three-phase windings is
m (neutral point voltage Vcom) is obtained by dividing the power supply voltage by the parallel impedance of the impedance of the U-phase winding U and the impedance of the W-phase winding W, and the impedance of the ■-phase winding V. In other words, it is established as a voltage value according to the impedance ratio of the windings of each phase. As can be seen from the above, the neutral point voltage measured as described above is due to the change in the value of the inductance L of the three-phase windings U, V, and W wound around the core 43. Since it is generated in accordance with the mode, the three-phase winding U,
If the pattern of energization to be applied to V and W is known, the position of the magnetic poles magnetized on the rotor 30 and the positions of the three-phase windings U, V, and W can be determined based on the measured value of the neutral point voltage. Relative positional relationships can be determined. When the rotor 30 of the brushless DC motor is in a stopped state, the three-phase windings U and V. W is energized at 180 degrees, and the three-phase windings star-connected are commonly connected at a connection point Pc. The voltage V com (neutral point voltage Vcom) that appears at transient time at m can be measured as a value corresponding to the impedance ratio of the impedances of the three-phase windings. The measured value does not change even when the temperature of each winding changes,
Furthermore, since a measured voltage value with a large fluctuation range can be obtained in accordance with the fluctuation of the inductance of the winding of each phase, high-resolution voltage measurement can be easily performed, and there are many other features. Embodiments Hereinafter, specific details of the method for driving a brushless DC motor without a position sensor according to the present invention will be explained in detail with reference to the accompanying drawings. Fig. 1 is a block diagram used to explain the method of driving a plusless DC motor without a position sensor according to the present invention;
The figure is a partial circuit diagram of a drive circuit for a brushless DC motor without a position detector, Figure 3 is a partial sectional view showing the schematic configuration of a plusless DC motor without a position detector, and Figure 4
6 to 6 and 11 are diagrams for explaining rotor stop position detection, and FIGS. 7 to 10 are waveform example diagrams for explaining the configuration principle and the operating principle. In FIG. 1, reference numeral 1 denotes a control device. As this control device, for example, a device including a microprocessor unit can be used, and the microprocessor unit mentioned above can be used. For example, μPD78312 manufactured by Hondenki Co., Ltd., M37700 series manufactured by Mitsubishi Electric Corporation, H8 series manufactured by Hitachi, Ltd., etc. can be used. Further, 22 is a storage device, 3 is a timer, 4 is a commutation control circuit,
5 is a commutation switch circuit, 6 is a current control circuit, 7 is an integrator, 8 is a pulse width modulation circuit, 9 is an AD converter and a voltage measurement circuit, and 31 is a positiveless DC motor without a position detector. Three-phase motor windings U, V, W (in the following explanation, U-phase winding, ■ phase winding, W-phase winding,
(Sometimes written as 3-phase windings U, V, W)
Pcom in the figure indicates a connection point where one ends of the three-phase windings U, V, and W are commonly connected. Note that the voltage Vcom appearing at the connection point Pcom where the ends of the three-phase windings U, V, and W are commonly connected is referred to as the neutral point voltage V com or the midpoint voltage V c in the following description. It is stated as om. The commutation control circuit 6 shown by block 5 in FIG. 1, the current control amount 6 shown by block 6, the integral circuit 7 shown by block 7, etc. are located at one point in FIG. Specific configuration examples are shown in component parts 5 to 7, which are shown surrounded by chain line frames. In Figure 2, 10 to 15, 26, 28 are resistances, 1
6 to 21 are transistors that operate as commutation switches;
22 to 24, 27, and 29 are capacitors, and 25 is a field effect transistor for current control. In Figures 1 and 2, three-phase windings U, V,
Although only W is shown, if a ferromagnetic core is used as the core (magnetic path) for the mechanical part of a plusless DC motor that does not have a position detector, any configuration of the DC motor can be used. Although a motor can also be used, for example, one having a laminated core as illustrated in FIG. 3 can be used. In FIG. 3, 30 is a motor rotor, 32 is a rotating shaft + aa, 34 is a bearing, 35, 36 is a spring, 37 is a contact spring, 38 is a metal-based printed circuit board that is the base of the motor stator, 39 is a screw, 40 is a flexible connection wire substrate, 41, 42 is a reinforcing tape, 43 is a core, 44 is a motor winding, 45 is a permanent magnet, and 46 is a magnetic disk holder. In the positiveless DC motor without a position detector of the present invention, the three-phase windings U, V, and W are star-connected,
The commonly connected connection point Pc. m&: The voltage V c o m that appears is AD by drawing the line j.
It is adapted to be supplied to the converter and voltage measuring circuit 1. Moreover, a plurality of magnetic poles are formed in the single rotor 30 according to a predetermined magnetization pattern. FIG. 6 shows an example in which four magnetic poles are magnetized. Now, in order to rotate the stopped rotor in a predetermined rotation direction, it is necessary to adjust the position of the magnetic poles of the stopped rotor, which are magnetized in a predetermined pattern, relative to the windings of each phase of the motor. It is necessary to supply drive current to the windings of each phase at a predetermined commutation timing according to the positional relationship of the In order to start rotating the rotor in a predetermined rotation direction from a stopped state, first, at startup, the relative phase relationship between the position of the rotor's magnetic poles and the windings of each phase of the motor in the stopped state is determined in advance. This is how it is detected. Figure 6 shows the relative phase between the position of the rotor's magnetic poles and the windings of each phase of the motor during the stopped state, which are required in order to make the stopped rotor start rotating in a predetermined rotational direction. It is a figure for explaining the detection method of the stop position of the rotor of the present invention for detecting the relationship. The three views shown in FIG.
The position of the magnetic poles magnetized and the three-phase windings U, V, W
This is a representative example of three states in which the relative positional relationship with the position of This diagram shows all the energization modes (six types of energization modes) that occur when energization is carried out. The numbers 1, 2, 3...6 in the figure are used to distinguish between the 6 types of energization patterns. belongs to. Furthermore, the three diagrams shown in FIG. 6(b) show the position of the magnetic poles magnetized on the rotor 30, the three-phase winding U,
The relative positional relationship with the positions of V and W is shown in (a) in Figure 6.
In the case shown in the three figures shown in
For each of the three figures described above, when the three-phase windings U, V, and W connected in star connection are energized in the six energization patterns shown in FIG. 6(C), the three-phase windings Lines U, V. The voltage V appearing at the commonly connected connection point Pcom of W
This is a diagram showing what c o m will be, and it is a diagram showing what the c o m will be, and it is a diagram showing what the c o m will be like. The arrows indicated with numbers indicate the energization patterns indicated with the same number among the six types of energization patterns indicated with numbers 1 to 6 shown in FIG. 6(c). The three-phase winding U is star-connected. ■When W is energized, the voltage V that appears at the common connection point Pcom of the three-phase windings U, V, and W
com measurement points are shown. In addition, the above-mentioned 6th
In the three figures shown in (b) of the figure, the horizontal axis is time and the vertical axis is voltage. When the rotor is at rest, the three-phase winding U. ■, When W is energized 180 degrees by a power supply with a voltage value of Vcc, the star-connected three-phase winding U
, V, and W are commonly connected at the common connection point P colI.
) is, for example, 1 of the energization mode in FIG. 6(c),
As shown in 3.5, the positive terminal of the power supply is connected to the outer end of the winding of one phase of the star-connected three-phase windings U, V, and W, and the positive terminal of the other two phases is When the negative terminal of the power supply is connected to the outer end of the winding, it becomes Vcc/3,
For example, 2.4 of the energization mode in FIG. 6(c)
．． 6, the positive terminal of the power supply is connected to the outer ends of the windings of two of the star-connected three-phase windings U, V, and W, and the winding of the other one phase. When the negative terminal of the power supply is connected to the outer end of the power supply, the voltage becomes 2Vcc/3. In brushless DC motors, which do not have an actual position sensor, when the rotor is at rest, the current is passed through the transistors of the commutation switch, which are connected in series with the three-phase windings @U, V, and W. When the three-phase windings U, V, and W are energized 180 degrees by a power supply with a voltage value of Vcc, the star-connected three-phase windings U, V, and W are commonly connected. The neutral point voltage VcomL± that appears at point Pco- during steady state differs from the voltage value described above by the slight voltage drop due to the transistor described above, but here, ignoring the slight voltage drop mentioned above, Give an explanation. That is, when the rotor is stopped, the DC voltage Vcc
In the steady state when the three-phase windings U, V, and W are energized at 180 degrees from the power source, the influence of the inductance L of the windings of each phase can be ignored. Referring to the equivalent circuit diagram shown in FIG.
In this case, the neutral point voltage ■colI is Vc as described above.
It is easy to understand that the voltage value is expressed as c/3 or 2Vcc/3. In addition, when the rotor is stopped and the three-phase windings U, V, and W are energized 180 degrees by a DC voltage Vcc power source, the neutral point voltage Vcom during the transient period is shown in the lower part of Fig. 11. From the shown equivalent circuit, the equation for VQ and the equation for vh shown in FIG. 11 at the time of transition are obtained. By the way, the three-phase windings U, V, and W in a brushless DC motor without a position sensor are wound around a core 43 made of ferromagnetic material, as shown in FIG.
The inductance values of each of the three-phase windings U, V, and W vary because the amount of magnetic flux that passes through the portion of the core around which each winding is wound changes the magnetic permeability of that portion. The amount of magnetic flux that passes through the core around which each winding is wound is determined by the amount of magnetic flux generated from each winding that flows to the core and the amount of magnetic flux that flows to the rotor, depending on the magnitude and direction of the current flowing through each winding. Since it is the vector sum of the amount of magnetic flux flowing through the core between the magnetic poles formed by magnetism, the inductance value of each winding is determined by the position of the magnetic poles formed by magnetization on the rotor 30 and the three-phase winding. Which of the six types of energization modes when 180 degree energization is performed on the three-phase windings U, V, and W, and the relative positional relationship with the positions of U, V, and W? This will vary depending on the combination of the type of energization pattern and the type of energization pattern in which energization is performed. Therefore, the star-connected three-phase windings U, V,
A 180-degree energization of W is carried out sequentially using each of the six types of energization patterns described above, and the neutral point Pcom is
If we look at the state of the six neutral point voltage values during transient times, which were individually measured in , we can see that the position of the magnetic poles formed by magnetization on the rotor 30 in the stopped state, the three-phase winding U, The relative positional relationship with the positions of V and W can be known. In the brushless DC motor without a position detector according to the present invention, when starting the motor, the position of the magnetic poles formed by magnetization on the rotor 30 in a stopped state and the three-phase windings U and V are determined.
, in order to know the relative positional relationship with the position of W, first,
A control signal is given from the control device 1 to the commutation control circuit 4 via the transmission line e, and 180 degree energization to the three-phase windings U, V, and W is performed for each of the six types of energization patterns described above. A predetermined short time (in the following explanation, it is assumed to be 100 microseconds) set in the timer 3, and the setting of the above time is performed from the control device 1 to the timer 3 via the transmission line a. ) The commutation control circuit 4 is operated so that the commutation is performed sequentially. The control device 1 also provides a signal to the pulse width modulation circuit 8 via the transmission line k, so that the 180-degree energization of the three-phase windings U, V, and W can be performed in the six types of energization patterns described above. During each period, a signal with a duty cycle of 100% is supplied from the pulse width modulation circuit 8 to the integration circuit 7, so that the current control circuit 6 is continuously energized. The above-mentioned timer 3 measures 90 microseconds for each 100 microsecond period in 180-degree energization using six types of energization patterns sequentially applied to the three-phase windings U, V, and W for each 100 microsecond period. When microseconds have elapsed, a signal is given to the control bag [1 connected to the transmission line n, and the control device 1 gives a signal to the AD converter and voltage measurement circuit 9 via the transmission line n. In the AD converter and voltage measurement circuit 9, three-phase windings U and V
, W. When 90 microseconds have elapsed for each 100 microsecond period of 180 degree energization using six types of energization patterns sequentially performed on W,
The neutral point voltage Vcom supplied from the neutral point Pcom via the transmission line j is AD converted, and the neutral point voltage Vcam at that time is applied to the control bag w1 via the transmission line 0. The voltage V c o m at the neutral point P c am of the star-connected three-phase windings U, V, and W measured as described above when the rotor 30 is in a stopped state is as shown in FIG. of(
The voltages are respectively indicated by arrows 1 to 6 in each of the three figures in b). (Table 1) The control device 1 supplies the data of the neutral point voltage Vcom to the storage device I2 via the transmission line C, and stores it in the storage device M2. Data on the neutral point voltage values of the portions indicated by arrows 1 to 6 in FIG. 6(b), that is, the three-phase windings U and V. At the time when only 90 microseconds have elapsed during each 100 microsecond period of energization at 18'O degrees by six types of energization patterns performed sequentially on W; The data of the voltage value of the sexual point is
For example, assume that the values are as shown in Table 1 above. By the way, the data group of neutral point voltage values in the portion indicated by arrows 1, 3°5 in FIG. 6(b) is such that the neutral point voltage Vcom is set to Vcc/3 in a steady state This is the first data group of the neutral point voltage Vcom obtained during the transient period for the current conduction pattern, and the sixth data group is
The data group of the neutral point voltage value of the part indicated by arrow 2.4.6 in (b) of the figure shows the transient voltage value for the energization pattern in which the neutral point voltage Vcom is 2Vcc/3 in the steady state. The neutral point voltage V c obtained when
o m is the second data group, but in the control device l, the above-mentioned storage device! The first data group and the second data group stored in t2 are sequentially read out via the transmission line d, and each data in the first data group is read out from the first data group.
Find the difference from the data that shows the minimum neutral point voltage value in the data group, and for each data in the second data group, show the maximum neutral point voltage value in the second data group. Find the difference with the data and invert the minus sign to a plus sign. The values shown in the Difference column in Table 1 are the comparative numerical values obtained as described above. Then, the first data group and the second
Find the largest value among the comparison values for each data group. In the example in Table 1, the largest comparison value in each of the first data group and the second data group is obtained when the energization pattern is 6. As mentioned above, the 180-degree energization of the three-phase windings U, V, and W is performed sequentially for each of the six types of energization patterns described above for a predetermined time period set in the timer 3, Star-connected three-phase windings U and V
, the voltage value V c o m at the neutral point P c o rn of W
By measuring the position of the magnetic poles formed by magnetization on the rotor 30 in a stopped state and the three-phase windings U and V,
, and the relative positional relationship with the positions of W can be known. FIG. 7 is a diagram illustrating the results of measuring the neutral point potential for all of the six types of energization patterns described above at a large number of positions within the range of one rotation of the rotor 30, and FIG. 30 is an example of the measurement results of the neutral point potential measured for one of the 6111 type energization patterns described above at a large number of positions within the range of one rotation of the 30-meter. Looking at the waveform diagrams shown in fJS7 and Figure 8. 360 electrical degrees (in the example described, 1 mechanical angle)
It can be seen that it consists of a collection of six waveforms with six peaks in a range of 80 degrees), and that the intersection of each waveform is at a specific electrical angle. Furthermore, if we look at the respective sizes of the six waveforms at arbitrary electrical angle positions from the waveforms in the figure, we can see the positions of the magnetic poles formed by magnetization on the rotor 30 in a stopped state and the three-phase windings. It can be seen that the relative positional relationship with the positions of U, V, and W can be known. In the above description, the 3-phase windings U, V, and W are energized at 180 degrees using 6 types of energization patterns, and each energization pattern is 100 microseconds long, resulting in a total of 600 microseconds. It was supposed to use a time of seconds, but the three-phase winding U, star-connected as described above,
The magnitude of the change in voltage that appears at the neutral point Pcom of V and W during a transient is as in the conventional example described above, and the magnitude of the change in voltage obtained at the terminals of the windings of each phase as in the conventional example As is done in the brushless DC motor disclosed in the aforementioned Japanese Patent Application Laid-open No. 63-69489, a current detection resistor is star-connected with a voltage generated in response to the current flowing through the motor windings. The resolution of the AD converter used to measure the voltage is much higher than the measured voltage obtained when detecting the back electromotive force generated in the phase windings U, V, and W. If it is the same as in the conventional example, voltage can be measured with high accuracy. Therefore, in the case of a brushless DC motor that does not have a position sensor according to the present invention, for example, for the first data group, first obtain the neutral point voltage V com data of 1 of the energization pattern, and then Regarding the data group, first, the neutral point voltage ■c of energization pattern 2. m data is obtained, and then the neutral point voltage V c of other energization patterns 3 and subsequent ones in the first data group is determined. When m data is obtained, the difference between that data and the neutral point voltage V c o m data of 1 of the energization pattern described above is
If the magnitude is greater than a predetermined value, the neutral point voltage V c due to another energization pattern to be performed thereafter
om data is not obtained, and the neutral point voltage Vc of other energization patterns after 4 in the second data group is
When the om data is obtained, if the difference between the data and the neutral point voltage Vcom data of the above-described energization pattern 2 is greater than a predetermined magnitude, other energization patterns to be performed thereafter are determined. Even if we adopt the method of not determining the neutral point voltage 700 m data based on the position of the magnetic poles formed by magnetization on the rotor 30 in the stopped state and the three-phase windings U and V. The relative positional relationship with the position of W can be known, and according to such a method, predetermined data can be obtained within a time shorter than the above-described measurement time of 600 microseconds. Furthermore, as is clear from the equivalent circuit shown in FIG. 11, the three-phase windings U and V are star-connected. As mentioned above, the voltage value at the neutral point that appears at the neutral point Pcom of W, which is obtained by dividing the power supply voltage by the ratio of the impedance of the three-phase winding, is determined by changes in the ambient temperature and changes in the winding and other parts. Even if the resistance value of the winding changes due to heat generation, it will not change. In this way, assuming that the power supply voltage is divided by the impedance ratio of the three-phase windings, the voltage appearing at the neutral point P co m of the star-connected three-phase windings U, V, and W is as follows: This is the only measurement method that allows absolute value comparison as long as the power supply voltage is stable. Therefore, we sequentially obtain data by measuring neutral point voltages that can be compared in absolute value, and among the obtained data, for the data of the first data group, the neutral point voltage V in the steady state
c c / 3, and for the data of the second data group, the neutral point voltage 2 in steady state
When the data is sequentially compared with V c c / 3 and a difference greater than a predetermined value is obtained, the rotor 30 in the stopped state is formed by magnetization based on that data. It is possible to know the relative positional relationship between the position of the magnetic pole and the position of the three-phase windings U, V, and W. When the rotor stop position is detected using the rotor stop position detection method described above, the shortest measurement time required is the measurement time corresponding to one energization pattern, i.e. , if the energization time of each energization pattern is 100 microseconds as in the previous example, then 10
It is also possible to complete the voltage measurement for detecting the rotor stop position in a time of 0 microseconds. As described above, in the method of detecting the stop position of a rotor in a brushless DC motor without a position detector according to the present invention, the three-phase windings U and V are star-connected. The voltage at the neutral point that appears at the neutral point Pcom of W as the power supply voltage divided by the impedance ratio of the three-phase winding. Even if the resistance value changes, the neutral point voltage, which is obtained as a large voltage value without changing, is measured to obtain data on the rotor's stopping position, so the conventional position detector described above can be used. All the problems in the method of detecting the stop position of the rotor in a brushless DC motor that does not have this type of brushless DC motor can be solved. Next, the position of the magnetic poles formed by magnetization on the rotor 30 in a stopped state and the three-phase windings U and V. When information on the relative positional relationship with the position of W is given to the control device 1, the control device 11 determines the position of the magnetic poles formed by magnetization on the rotor 30 in the stopped state given to it and the three phases. Based on the information on the relative positional relationship with the positions of the windings U, V, and W, a rotating drive current that rotates the rotor 30 in a predetermined rotation direction is transmitted from the commutation switch circuit 5 to the three-phase A control signal is sent to the commutation control circuit 4 via the transmission line e so that the winding of two phases selected among the windings MU, V, and W can be supplied with the winding for a short period of time. The commutation control circuit 4 supplies a commutation switch switching signal generated based on the control signal given to it from the control device 1 to the commutation switch circuit 5 via the transmission 4@r. The commutation switch circuit 'I85 is set to 3 so that the rotor 30 can be rotated in the normal rotational direction by energization at an electrical angle of 120 degrees.
The current is supplied to the windings of two selected phases among the phase windings U, V, and W for a short period of time. The above-mentioned energization time is determined by various conditions such as the torque constant of the motor and the moment of inertia of the rotor 30, and is set to a time value within a range in which no reverse torque is generated in the rotated rotor 30. The three-phase windings U, V, which are star-connected as described above,
When the windings of the selected two phases of W are energized at an electrical angle of 120 degrees and the rotor 30 starts rotating, the windings of the phases that are not energized are energized as the rotor 30 rotates. A back electromotive force is generated. When the windings of two phases selected among the three-phase windings U, V, and W connected in a star connection are energized at an electrical angle of -20 degrees, the three-phase windings mu, v. At the commonly connected connection point (neutral point) Pea■ of W, a DC voltage determined according to the power supply voltage is generated, but at the neutral point Pcom, there is a A voltage having a voltage value of 173 of the generated back electromotive voltage appears in a state superimposed on the DC voltage determined according to the voltage 'g'e and voltage described above. Since the voltage generated at the neutral point Pcow in response to the back electromotive force generated in the windings of the non-energized phase includes rotational phase information of the rotor, the above-mentioned neutral point Pcow
It is considered possible to extract the rotational phase information of the rotor based on the voltage appearing at t. By the way, when a selected two-phase winding among the three-phase windings U, V, and W is energized at an electrical angle of 120 degrees, the above-mentioned voltage that occurs at the neutral point Pea■ in accordance with the power supply voltage The DC voltage becomes Vcc/2 when a power source with a voltage of Vcc is connected to both ends of the series-connected two-phase windings that are energized. ,
In an actual motor, the transistors of the commutation switch circuit 5 are connected in series between both ends of the series-connected two-phase windings that are energized and the power supply.
The DC voltage generated at the neutral point Pcow according to the power supply voltage is different from the voltage value of Vcc/2 described above, and the voltage value will fluctuate if the power supply voltage fluctuates. It becomes what it is. Therefore, the voltage value of the voltage appearing at the neutral point Pcow while the rotor 30 is rotating includes voltage fluctuations in the DC voltage that occur in response to the fluctuating power supply voltage. It goes without saying that it is not possible to obtain rotational phase information of the rotor 30 by simply measuring the voltage value of the voltage appearing at the neutral point Pcow.
In order to accurately obtain rotational phase information, it is necessary to adjust the neutral point P according to the power supply voltage while the rotor 30 is rotating.
It is necessary to accurately know the voltage value of the DC voltage generated on the cow. While the rotor 30 is rotating, one way to know the voltage value of the DC voltage generated at the neutral point Pcow according to the power supply voltage is to connect two resistors with the same resistance value between the power supply terminals, for example. Connect the series connection circuit by the device,
It is conceivable to measure the voltage at the connection point of the two resistors mentioned above using, for example, an AD converter, but it is extremely impractical to use two resistors with the same resistance value. Have difficulty. Therefore, for example, as the two resistors mentioned above, we select and use precision resistors with a resistance value error of ±0.5% from among commonly available precision resistors, and as an AD converter for voltage measurement, we use, for example, an 8-bit resistor. Using a device with resolution, the above A
Considering the case where voltage is measured in the 5 volt voltage range used as the voltage of the motor drive power supply using a D converter, the voltage measurement value obtained in this case includes the AD used for voltage measurement. This will result in an error greater than the ILSB of the converter, resulting in unsatisfactory measurement results.
It is not possible to accurately determine the voltage value of the DC voltage generated at the neutral point Pcom depending on the power supply voltage by means of generating and measuring the voltage value of 2 using a resistor network. So, actually any two in the three-phase windings U, V, W
With the power supply connected between the ends of the phase windings, the neutral point P c
I thought of a method that would measure the voltage appearing at When the rotor 30 is rotating, the voltage value is such that different back electromotive voltages generated depending on the rotational speed of the rotor 30 are superimposed on the winding of the phase that is not energized. - It is not possible to accurately know the voltage value of the DC voltage generated at the neutral point Pcow according to the power supply voltage. Therefore, by sequentially changing the combination of the two-phase windings in the three-phase windings U, V, and W, for example, first, current flows from the end of the U-phase winding to the V-phase end. Connect the power supply to the ends of the U and V phase windings and measure the voltage value generated at the neutral point Pcow, and then. ■ In a state where current flows from the end of the phase winding to the end of the W phase, connect the power supply to the end of the W phase winding and connect the neutral point Peom.
Measure the voltage value generated at W, then connect the power supply to the end of the U-phase winding so that current flows from the end of the W-phase winding to the U-phase end, and connect the power supply to the neutral point P. It was conceived to accurately determine the voltage value of the DC voltage generated at the neutral point Pcoo+ according to the power supply voltage by measuring the voltage value generated at the cow and arithmetic averaging the above three measured values. The method for measuring the voltage at the neutral point p cots described above can be performed by energizing for a short time to the extent that the phase of the back electromotive voltage does not change without affecting the torque of the motor. Further, the voltage at the neutral point PCOI11 described above can be accurately determined by determining the average value of the six neutral point voltage data shown in Table 1 described above. Now, when the rotor 30 is rotating, the waveform of the back electromotive force generated in each of the three-phase windings is shown in FIG. 9 (a).
The voltage waveform shown by the solid line in (e) is the one shown in FIG. 9, and the voltage waveform shown by the solid line in (a) of FIG. 3 in condition
This is the voltage waveform of the back electromotive force generated in each of the phase windings, and the voltage waveform illustrated by the solid line in FIG. This is the voltage waveform of the back electromotive voltage generated in each of the three-phase windings while rotating with a rotation phase delayed compared to , is a voltage waveform of a back electromotive voltage generated in each of the three-phase windings when the rotor 30 is rotating at an advanced rotational phase compared to the state where the rotor 30 is rotating at the correct phase. In addition, when the rotor 30 is rotating, the neutral point P
The waveforms of the voltage appearing in the co layer are shown in (a) to (c) in Figure 9.
), and the voltage waveforms shown by the two-dot chain lines in (,) in FIG. 9 indicate that the rotor 30 is in the correct phase. This is the voltage waveform that appears at the neutral point Pcom while rotating, and the voltage waveform illustrated by the two-dot chain line in FIG. 9(b) indicates that the rotor 30 is rotating in the correct phase. This is the waveform of the voltage that appears at the neutral point Pcow when the motor is rotating with a rotation phase that is delayed compared to the state where the motor is rotating. Furthermore, the voltage waveform illustrated by the two-dot chain line in FIG. This is the waveform of the voltage appearing at the sex point Pcow. In addition, in (a) to (c) of FIG. 9, the voltage waveforms Eu shown by dotted lines,
Ev and Ew are the voltage components generated at the neutral point Peas by the back electromotive force generated in the three-phase windings U, V, and W, respectively, but the voltage actually appearing at the neutral point Pcow is In (a) to (c) of FIG. 9, the waveform is as shown by the two-dot chain line. In addition, the voltage waveform of the composite voltage due to the back electromotive force of the three-phase windings U, V, and W appearing at the neutral point PcolB when the rotor 30 is rotating in the correct phase is (a ) becomes a triangular wave as shown by the two-dot chain line. The waveform indicated by the thick solid line in FIG. 9(a) is the waveform due to the back electromotive force of the U phase of the three-phase windings U, V, and W. Therefore, the voltage appearing at the neutral point Pcow is (
If the phase control is performed to form a triangular wave as shown by the two-dot chain line in a), the rotor 30 can be rotated in the correct rotational phase. When the neutral point Pcom
L: The phase control operation performed on the rotor based on the voltage that appears is performed by the operation of each component shown in FIG. 1 under the control of the control device 1. Now, four methods for controlling the phase of rotation f-30 will be sequentially explained with reference to FIG. [1] Star-connected three-phase winding tJ, v,
The voltage value Vcom (see Fig. 10) at the neutral point in a state where no back electromotive force exists at the neutral point Pcom of w is the voltage value measured by any of the various measurement methods described above. is stored in advance in the storage device 2, and the three-phase winding mu is star-connected. ■, The voltage measured by the AD converter and the voltage measurement circuit 9 while the rotor 30 is being rotated with the windings of the selected two phases of W being energized at an electrical angle of 120 degrees. The measured value of the voltage at the sex point Pcom is sent to the control device via the transmission line 0! ! 1 is given. In the control device i1, the measured value of the voltage at the neutral point Pcom measured by the AD converter and the voltage measuring circuit 9 is converted into a DC voltage value Vco generated according to the power supply voltage stored in the storage device 2.
At time t1, which coincides with m, the timer 3 is caused to start measuring time. and a predetermined time 1 from said time t, 1.
A commutation control signal is given to the commutation control circuit 4 at the time t2 when "a" has elapsed, so that the commutation operation is performed in the commutation switch circuit 5 at the time t2. Next, the control device 1 first sets the neutral point P cow in the three-phase winding after time t2 when the commutation operation is performed.
When Tb is the time from t2 to t3 until time t3 when it is detected that the measured value of the voltage again matches the voltage value Vcow at the neutral point Pcow in a state where no back electromotive force exists Then, a control operation is performed such that the next commutation operation is performed at time t4 approximately after a time of (Ta+Tb)/2=Tc from time t3. Also, the control device! 1 is the first time 3 after the above-mentioned time t4
At time t5, not shown, when it is detected that the voltage at the neutral point P cow in the phase winding again matches the neutral point voltage value V cow in the state where no back electromotive force exists,
The control operation for performing the operations from the time tl to the time t5 described above is performed sequentially by setting the time value Te as a predetermined time Ta, thereby causing the rotor 30 to rotate with the correct rotational phase. made to be driven. [2] The voltage value Vcom (see Fig. 10) at the neutral point in the state where no back electromotive force exists at the neutral point Pcom of the star-connected three-phase windings U, V, and W is as described above. Voltage values measured by any one of various measurement methods are stored in advance in a memory bag M2, and the three-phase winding U is star-connected. ■, The voltage measured by the AD converter and the voltage measurement circuit 9 while the rotor 30 is being rotated with the windings of the selected two phases of W being energized at an electrical angle of 120 degrees. The measured value of the voltage at the sex point Pcom is sent to the control device via the transmission line 0! 1, and the measured value of said voltage is stored in the storage device! It is stored in 2. The control device 1 is a neutral point P of the three-phase windings at the time when the current supply to one phase winding among the three-phase windings U, V, and W ends.
The voltage value A of cow, that is, the neutral point P stored in the storage device 2. The stored value B of the voltage at the point P colI is calculated to obtain the voltage value C=(A+B)/2. Then, at the time when the measured value of the voltage at the neutral point Pcow in the three-phase winding matches the voltage value C described above, a commutation control signal is given to the commutation control circuit 4, and the commutation is performed by the commutation switch circuit 5. A control action is repeatedly performed to cause the action to take place. [3] The voltage value Vcom (see Fig. 10) at the neutral point in the state where no back electromotive force exists at the neutral point Pcom of the star-connected three-phase windings U, V, and W is as described above. The three-phase winding U has a voltage value measured by one of various measurement methods stored in advance in the storage device 2, and is star-connected. The voltage measured by the AD converter and the voltage measurement circuit 9 while the rotor 30 is being rotated with the windings of two phases selected from v and W being energized at an electrical angle of 120 degrees. The measured value of the voltage at the sex point Pcom is given to the control device 1 via the transmission line 0, and the measured value of the voltage is stored in the storage device I! It is stored in 2. Control device! In step 1, the voltage difference W between the voltage value of the neutral point Pcow in the three-phase winding measured before and after the commutation operation stored in the storage device 2 is calculated, and The voltage at the neutral point Pcow in the three-phase winding measured at the time when the current operation was performed and the voltage detected immediately before the time of the next commutation operation performed following the aforementioned commutation operation. The voltage difference X between the voltage at the neutral point Pcom in the three-phase winding is calculated, and the neutral point P in the three-phase winding detected before and after the time when the next commutation operation described above is performed is calculated.
By calculating the voltage difference Y of colI, the neutral point Pc of the three-phase winding immediately after the next commutation operation described above is performed.
When the voltage difference shown by Z=X+(W/2)±Y with respect to the voltage of om is measured as the voltage of the neutral point Pcow in the three-phase winding, the next commutation operation described above is triggered. A control operation is repeated in which a commutation control signal is given to the commutation control circuit 4 to start the subsequent commutation operation, and then the commutation switch circuit 5 is caused to perform the commutation operation. [4] The voltage value V cow (see Fig. 10) at the neutral point in a state where no back electromotive force exists at the neutral point Pcom of the star-connected three-phase windings U, V, and W is as described above. The three-phase winding U has voltage values measured by any one of the various measurement methods described above stored in the storage device 2 in advance, and is star-connected. (2) The voltage is measured by the AD converter, converter, and voltage measuring circuit 9 while the rotor 30 is rotating and the windings of the two phases selected in W are energized at an electrical angle of 120 degrees. The measured value of the voltage at the neutral point p c, a m is the transmission line 0
The measured voltage value is stored in the storage bag [2]. The voltage at the neutral point Pco■ in the three-phase winding is the voltage value Vc at the neutral point in a state where no back electromotive force exists. From the time when it was measured that the voltage coincided with Peng, the difference between the measured voltage at the neutral point Pco■ in the three-phase winding described above and the voltage value at the neutral point Pco- in the absence of back electromotive voltage. When the voltage vE of the motor satisfies the relationship vE=KE/T with respect to the coefficient KE determined based on the back electromotive voltage of the motor and the time T, the commutation subsequent to the next commutation operation described above is started. Commutation control circuit 4 so that the current operation is started.
A control operation is repeatedly performed in which a commutation control signal is applied to the commutation switch circuit 5 to cause the commutation switch circuit 5 to perform a commutation operation. In any of the four phase control methods described above,
Under good commutation operation, the rotor 30 can rotate with the correct rotational phase and reach a state of steady rotation. (Effects of the Invention) As is clear from the above detailed explanation, the method for detecting the stop position of the rotor in a brushless DC motor without a position detector according to the present invention is as follows: A plurality of magnetic poles are formed by a predetermined magnetization pattern by selectively supplying current in five directions to the other end of each phase winding in the commonly connected three-phase winding. In order to detect the stop position of the rotor in a brushless DC motor that does not have a position detector in which the freely rotatable rotor is rotationally driven, it is necessary to
The rotor is energized when it is stopped by at least one energization pattern among all types of energization patterns when energization is carried out in the same energization mode, and the current flows individually through the windings of each phase during the energization described above. Changes in inductance that occur in the windings of each phase due to the magnetic flux that is the vector sum of the magnetic flux that passes through the individual magnetic paths of each winding of each phase and the magnetic flux that passes through the individual magnetic paths described above due to the magnetic poles of the rotor. Correspondingly, measure the voltage generated at the common connection end of the three-phase winding as the ratio of the impedance of the winding of each phase,
Since the relative position of the rotor's magnetic poles and the three-phase winding is detected based on the voltage value measured at the common connection end of the three-phase winding, the ambient temperature The measured voltage value does not change due to changes in winding temperature or winding temperature, and the voltage generated at the common connection end of the three-phase winding as a ratio of the impedance of each phase winding is large. Since the voltage indicates a fluctuation range, high-resolution voltage measurement can be easily performed using a single AD converter.Furthermore, the impedance ratio of each phase winding can be measured at the common connection end of the three-phase winding. Since the voltage generated as a voltage does not exceed the power supply voltage, there is no need for the voltage dividing means that was required in the voltage measurement in the conventional example described above, and furthermore, it Soldering for the common connection of each end of each of the three-phase windings requires only connecting one lead wire to the common connection part at the same time, so it can be constructed at low cost with fewer parts. In addition, when the current of the windings of each phase is passed through the current detection resistor and the voltage generated in the current detection resistor is measured, as in the conventional rotor stop position detection means described above, In addition to eliminating the problem of wasteful consumption of power, the present invention can satisfactorily solve all of the problems that have occurred in the prior art described above.

[Brief explanation of drawings]

Fig. 1 is a block diagram used to explain the method of driving a plusless DC motor without a position sensor according to the present invention;
The figure is a partial circuit diagram of a drive circuit for a brushless DC motor without a position detector, Figure 3 is a partial sectional view showing the schematic configuration of a plusless DC motor without a position detector, and Figure 4
Figures 6 to 11 are diagrams for explaining rotor stop position detection, Figures 7 to 10 are waveform side diagrams for explaining the configuration principle and operating principle, and Figures 12 to 11 are diagrams for explaining rotor stop position detection. 14
The figure is an explanatory diagram when voltage measurement is performed at the end of the stator winding. DESCRIPTION OF SYMBOLS 1... Control device, 2... Storage device, 3... Timer, 4... Commutation control circuit, 5... Commutation switch circuit,
6... Current control circuit, 7... Integrator, 8... Pulse width modulation circuit. 9... AD converter and voltage measurement circuit, 10 to 15.2
6.28...Resistance, 16-21. Ql-Q6...Transistors operating as commutation switches, 22-24.
27, 29... Capacitor, 25... Field effect transistor for current control, 30... Motor rotor. 32...Rotating shaft, 33.34...Bearing, 35
36...Spring, 37...Contact spring, 38...Metal printed circuit board serving as the base of the motor stator, 39...Screw, 40...Flexible connection wire board, 41. 42...Reinforcing tape,
43...Core, 44...Motor winding, 45...Permanent magnet, 46...Magnetic disk holder, U, V, W
...Three-phase motor winding in a positiveless DC motor without a position detector, Pcom...Three-phase winding U,
V. A connection point (neutral point) where one end of W is commonly connected, V
com...Middle point voltage, Vcc 3oB+800J to the controller, 'h' l is 2 times, the main character (F Noyo, J running time is always 180o JIEv ”4 I: e a #T
Ta+Tb 0" 2

Claims (4)

[Claims] 1. A predetermined magnetization pattern is created by selectively supplying current in both directions to the other end of each phase winding in a three-phase winding in which one end of each phase winding is commonly connected. A method for detecting the stop position of a rotor in a brushless DC motor without a position detector in which a freely rotatable rotor having a plurality of magnetic poles is rotationally driven by A state in which the rotor is stopped while the three-phase windings are energized in an electrical angle of 180 degrees in each individual energization pattern of all types of energization patterns when energization is carried out at 180 degrees in electrical angle. means for energizing the coils, a magnetic flux that passes through individual magnetic paths for each phase winding due to the current flowing individually through the windings of each phase when energized, and each individual magnetic path described above due to the magnetic poles of the rotor. The voltage that occurs at the common connection end of the three-phase winding as a ratio of the impedance of the winding of each phase corresponds to the change in inductance that occurs in the winding of each phase due to the magnetic flux that is the vector sum of the magnetic flux that passes through the and a means for detecting the relative position of the magnetic poles of the rotor and the three-phase windings based on the voltage values individually measured for each of the individual energization patterns described above. A method for detecting the stop position of a rotor in a brushless DC motor that does not have a position detector. 2. When the three-phase winding is energized in an electrical angle of 180 degrees, all types of energization patterns are individually energized at the common connection end of the 3-phase winding. The voltage value measured at
A first group of measured voltage values showing a measured voltage value close to the voltage value of No. 3, and a second group of measured voltage values showing a measured voltage value close to 2/3 of the power supply voltage appearing at the common connection end of the three-phase winding in a steady state. 2
For each measured voltage value group described above, calculate the difference voltage between the minimum voltage value and the maximum voltage value in absolute value, and compare the difference voltages determined for each of the above groups. The rotation in the brushless DC motor without a position detector according to claim 1, wherein the relative position between the magnetic poles of the rotor and the three-phase winding is detected by the energization pattern in which a large voltage difference is obtained. How to detect the child's stop position. 3. A predetermined magnetization pattern is created by selectively supplying current in both directions to the other end of each phase winding in a three-phase winding in which one end of each phase winding is commonly connected. A method for detecting the stop position of a rotor in a brushless DC motor without a position detector in which a freely rotatable rotor having a plurality of magnetic poles is rotationally driven by Means for energizing three-phase windings when the rotor is stopped by at least one of all types of energization patterns when energization is carried out in a 180-degree energization mode; The magnetic flux that is the vector sum of the magnetic flux that passes through the individual magnetic paths of each winding of each phase due to the current flowing through the windings individually, and the magnetic flux that passes through the individual magnetic paths described above due to the magnetic poles of the rotor. Voltage measuring means for measuring the voltage generated at the common connection end of the three-phase winding as a ratio of impedance of each phase winding in response to a change in inductance occurring in the phase winding; The voltage value individually measured at the common connection end of the 3-phase winding when energized in the individual energization pattern is reduced to a voltage value that is 1/3 of the power supply voltage that appears at the common connection end of the 3-phase winding in a steady state. A first measured voltage value group showing close measured voltage values, and a second measured voltage value showing a measured voltage value close to 2/3 of the voltage value of the power supply voltage appearing at the common connection end of the three-phase winding in a steady state. For each measurement voltage value group described above, voltage measurement is performed for one energization pattern, and then the measured voltage values measured during energization in sequentially different energization patterns are performed for each measurement voltage group. However, if the voltage value is larger than the predetermined voltage value with respect to the previously obtained measured voltage value, the measured voltage value is determined by the position of the magnetic poles of the rotor and 3 depending on the energization pattern obtained. A method for detecting the stop position of a rotor in a brushless DC motor that does not have a position detector that detects the position relative to a phase winding. 4. A predetermined magnetization pattern is created by selectively supplying current in both directions to the other end of each phase winding in a three-phase winding in which one end of each phase winding is commonly connected. A method for detecting the stop position of a rotor in a brushless DC motor without a position detector in which a freely rotatable rotor having a plurality of magnetic poles is rotationally driven by Means for energizing three-phase windings when the rotor is stopped by at least one of all types of energization patterns when energization is carried out in a 180-degree energization mode; The magnetic flux that is the vector sum of the magnetic flux that passes through the individual magnetic paths of each winding of each phase due to the current flowing through the windings individually, and the magnetic flux that passes through the individual magnetic paths described above due to the magnetic poles of the rotor. Voltage measuring means for measuring the voltage generated at the common connection end of the three-phase winding as a ratio of impedance of each phase winding in response to a change in inductance occurring in the phase winding; The voltage value individually measured at the common connection end of the 3-phase winding when energized in the individual energization pattern is reduced to a voltage value that is 1/3 of the power supply voltage that appears at the common connection end of the 3-phase winding in a steady state. A first measured voltage value group showing close measured voltage values, and a second measured voltage value showing a measured voltage value close to 2/3 of the voltage value of the power supply voltage appearing at the common connection end of the three-phase winding in a steady state. For each measurement voltage value group described above, the voltage measurement is performed on the energization patterns sequentially, and the measured voltage values measured during energization in the sequentially different energization patterns performed for each measurement voltage group are as follows: If a measured voltage is obtained that provides a difference of more than a predetermined voltage value when compared with the steady state voltage value that appears at the common connection end of the three-phase winding for each group of measured values, The stop position of the rotor in a brushless DC motor that does not have a position detector that detects the relative position of the rotor's magnetic poles and the three-phase winding by the energization pattern from which the measured voltage value was obtained. Detection method.