JP3690341B2 - Brushless DC motor driving method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for driving a brushless DC motor by supplying a drive current from a power supply device.
[0002]
[Prior art]
Conventionally, it has been proposed and put into practical use that a brushless DC motor is adopted as a rotational drive source in various fields, paying attention to high efficiency.
[0003]
And as a cause of noise generation of brushless DC motor,
(1) Vibration and noise caused by torque fluctuation (tangential electromagnetic force on the inner circumference of the stator), and
(2) Vibration and noise due to normal electromagnetic force generated in a stator that does not contribute to torque are known.
[0004]
In particular, regarding the noise caused by the above (2), an electromagnetic force several times as large as that of the tangential electromagnetic force is generated, a large noise is generated, and it cannot be used as torque. Therefore, it is desired to reduce vibration and noise by reducing normal electromagnetic force.
[0005]
Further, when the frequency of the harmonic component of the electromagnetic force in the normal direction matches the stator resonance mode and frequency, the stator will resonate and generate more noise.
[0006]
In consideration of these, a motor driving method for reducing harmonic components of electromagnetic force has been proposed as follows.
(A) The fluctuation information of the electromagnetic force causing the annular vibration of the stator is stored in the electromagnetic force fluctuation storage device, the electromagnetic force fluctuation information is read according to the position information and supplied to the correction coefficient generation circuit, and the stator A control device for a rotating electrical machine (see Japanese Patent Application Laid-Open No. 11-341864), which generates a correction coefficient that cancels out the electromagnetic force harmonic component that is the main cause of the ring vibration of
(B) An inverter device for operating a BL motor and a reluctance motor, and by setting the energization angle to 144 ° ± 3 °, the fifth time harmonic component is minimized and low vibration and noise are possible. Inverter device (see JP 2000-308383 A),
(C) A DC voltage is switched by a switching element of an inverter circuit and applied to a motor, and a position detection signal is obtained by a position detection circuit by an induced voltage generated in a non-energized phase of the motor. When the position is detected by the control circuit to switch the motor energization, and when the motor is driven by PWM control of the switching element, a voltage component that makes the harmonic component included in the induced voltage in advance a positive torque is used. The motor is operated while being superimposed on the applied voltage of the motor, and a waveform pattern {voltage (PWM) pattern} corresponding to the applied voltage at the time of the most efficient operation is obtained and stored in the ROM. Motor control method in which the switching element is PWM-controlled using the waveform pattern shown in FIG. 3 JP), and
(D) A timing circuit that detects a timing between approximately 120 ° and 180 ° of the energization drive section, a waveform generation circuit that generates a sawtooth wave, and the on-duty of the soft PWM circuit by the voltage waveform of the waveform generation circuit A signal that gradually changes the on-duty of the soft PWM circuit between approximately 120 ° and 180 ° in the current-carrying drive section through the energization command generation circuit, the upper and lower transistor groups, and the power transistor group that are energized while changing. Is added to each phase of the three-phase motor coil group, and the on-duty at the end of energization is gradually lowered to energize the brushless DC motor drive circuit (Japanese Patent Laid-Open No. 10-66375).
[0007]
The conventional methods (a) to (d) described above are methods {n (n) in which the electromagnetic force vibration component causing the noise / vibration or the frequency component of torque ripple is directly superposed on the current harmonic component. Is a positive integer) A method of superimposing nth-order and n ± 1st-order harmonic currents to reduce the next noise / vibration components}, electromagnetic force vibration components, or current harmonics causing torque ripple The method is roughly divided into methods for minimizing components.
[0008]
[Problems to be solved by the invention]
If a method that directly removes the current harmonic component by superimposing the frequency component of the electromagnetic force vibration component or torque ripple causing noise and vibration is adopted, the current phase to be injected and the timing of the rotation position There is a possibility that the electromagnetic force vibration component or torque ripple may increase, and as a result, the noise / vibration component to be reduced may increase.
[0009]
When the method of minimizing the electromagnetic harmonic component or the current harmonic component causing torque ripple is adopted, it is almost impossible to minimize only the corresponding current harmonic component. Since current harmonic components are also affected, there is no guarantee that noise and vibration components can be sufficiently reduced. Further, the processing becomes complicated as compared with the case where the current harmonic component is superimposed.
[0010]
OBJECT OF THE INVENTION
The present invention has been made in view of the above problems, and an object of the present invention is to provide a brushless DC motor driving method and apparatus capable of reliably and sufficiently reducing electromagnetic force vibration and noise.
[0012]
[Means for Solving the Problems]
  Claim 1In the brushless DC motor driving method, when driving a brushless DC motor by supplying a driving current from a power supply device, a harmonic current of a different order is injected into a driving current including a harmonic component of a predetermined order. is there.
[0013]
  Claim 2The brushless DC motor driving method is a method in which the order of the harmonic current to be injected is set to at least one order.
[0014]
  Claim 3The brushless DC motor driving method is a method of injecting a seventh harmonic current of the fundamental wave into the driving current when driving the brushless DC motor by supplying the driving current from the power supply device.
[0015]
  Claim 4The brushless DC motor driving method is a method of setting the amount of the seventh harmonic current injected to 0.05 to 0.20 times the fundamental wave.
[0016]
  Claim 5The brushless DC motor driving method detects the rotational position of the rotor of the brushless DC motor from the motor neutral point signal, and supplies a driving current from the power supply device to the brushless DC motor based on the detected rotational position. .
[0017]
  Claim 6The brushless DC motor driving method detects the rotational position of the brushless DC motor rotor from the applied voltage of the stator of the brushless DC motor, the motor current, and the device constants of the brushless DC motor, and supplies power based on the detected rotational position. In this method, a driving current is supplied from the apparatus to the brushless DC motor.
[0019]
  Claim 7The brushless DC motor driving device drives a brushless DC motor by supplying a driving current from a power supply device, and injects harmonic currents of different orders with respect to the driving current including harmonic components of a predetermined order. Including harmonic current injection means.
[0020]
  Claim 8In the brushless DC motor driving apparatus, the order of the harmonic current to be injected is set to at least one order.
[0021]
  Claim 9The brushless DC motor driving apparatus drives a brushless DC motor by supplying a driving current from a power supply apparatus, and injects a seventh harmonic current of a fundamental wave into the driving current. It includes current injection means.
[0022]
  Claim 10The brushless DC motor driving apparatus employs a device that sets the amount of the seventh harmonic current to be injected to 0.05 to 0.20 times the fundamental wave as the seventh harmonic current injection means. is there.
[0023]
  Claim 11The brushless DC motor driving apparatus employs a brushless DC motor having a rotor having a permanent magnet embedded therein.
[0024]
  Claim 12The brushless DC motor driving apparatus employs a brushless DC motor having a concentrated winding type stator in which a winding is wound directly around a tooth portion.
[0025]
  Claim 13The brushless DC motor driving apparatus employs a brushless DC motor having a stator of 3 × N (N is an even number) slot and a rotor of 2 × N poles, harmonic component current injection means, harmonics Instead of the current injection means, a current injection means for injecting a current including harmonic currents of orders other than N × K ± 1st order to reduce harmonic noise of N × K (K is an integer of 1 or more) order. Adopted.
[0026]
  Claim 14The brushless DC motor driving apparatus employs a brushless DC motor having a 6-slot stator and a 4-pole rotor, and the current injection means has a 2K (K is an integer of 1 or more) order harmonic. In order to reduce the wave noise, an apparatus that injects a current including harmonic currents of orders other than 2K ± 1st order is adopted.
[0027]
  Claim 15The brushless DC motor driving apparatus detects a rotational position of a brushless DC motor rotor from a motor neutral point signal, and supplies a driving current from the power supply apparatus to the brushless DC motor based on the detected rotational position. It further includes power control means for controlling the power.
[0028]
  Claim 16The brushless DC motor driving device detects the rotational position of the rotor of the brushless DC motor from the applied voltage of the stator of the brushless DC motor, the motor current, and the device constants of the brushless DC motor, and supplies power based on the detected rotational position. The apparatus further includes power supply control means for controlling the power supply apparatus to supply a drive current from the apparatus to the brushless DC motor.
[0029]
  Claim 17The brushless DC motor driving apparatus employs a brushless DC motor that drives a compressor for a refrigeration apparatus or a compressor for an air conditioner.
[0031]
[Action]
  Claim 1In the brushless DC motor driving method, when driving a brushless DC motor by supplying a driving current from a power supply device, a harmonic current of a different order is injected into a driving current including a harmonic component of a predetermined order. Therefore, the effect of reducing electromagnetic force vibration and noise can be enhanced.
[0032]
  Claim 2In the brushless DC motor driving method, the order of the harmonic current to be injected is set to at least one order.Claim 1The same effect can be achieved.
[0033]
  Claim 3In this brushless DC motor driving method, when the brushless DC motor is driven by supplying the driving current from the power supply device, the seventh harmonic current of the fundamental wave is injected into the driving current. The following noise components can be greatly reduced.
[0034]
  Claim 4In the brushless DC motor driving method, the amount of the seventh harmonic current injected is set to 0.05 to 0.20 times the fundamental wave.Claim 3The same effect can be achieved.
[0035]
  Claim 5With this brushless DC motor driving method, the rotational position of the rotor of the brushless DC motor is detected from the motor neutral point signal, and the drive current is supplied from the power supply device to the brushless DC motor based on the detected rotational position. Therefore, the present invention can be applied to applications where it is difficult to mount the position detection sensor.Claim 4The same action as any of the above can be achieved.
[0036]
  Claim 6In this brushless DC motor driving method, the rotational position of the rotor of the brushless DC motor is detected from the stator applied voltage of the brushless DC motor, the motor current, and the device constants of the brushless DC motor, and based on the detected rotational position. Since the drive current is supplied from the power supply device to the brushless DC motor, it can be applied to applications where it is difficult to mount the position detection sensor.Claim 4The same action as any of the above can be achieved.
[0038]
  Claim 7In the case of the brushless DC motor driving apparatus, when driving the brushless DC motor by supplying the driving current from the power supply apparatus, the harmonic current injection means causes the orders different from the driving current including a harmonic component of a predetermined order. Therefore, the electromagnetic wave vibration and noise reduction effect can be enhanced.
[0039]
  Claim 8In the case of the brushless DC motor driving apparatus, the order of the harmonic current to be injected is set to at least one order.Claim 7The same effect can be achieved.
[0040]
  Claim 9When driving a brushless DC motor by supplying a drive current from a power supply device, the seventh harmonic of the fundamental wave with respect to the drive current is driven by the seventh harmonic current injection means. Since the current is injected, the 14th-order noise component can be greatly reduced.
[0041]
  Claim 10In the case of the brushless DC motor driving apparatus, the seventh harmonic current injection means that sets the amount of the seventh harmonic current injected to 0.05 to 0.20 times the fundamental wave is adopted. BecauseClaim 9The same effect can be achieved.
[0042]
  Claim 11In the brushless DC motor driving apparatus, since a brushless DC motor having a rotor in which a permanent magnet is embedded is adopted as the brushless DC motor, low vibration, low noise, and high torque are achieved. In addition toClaims 7 to 10The same action as any of the above can be achieved.
[0043]
  Claim 12In the brushless DC motor driving apparatus, a brushless DC motor having a concentrated winding type stator in which a winding is directly wound around a tooth portion is adopted. In addition to achieving high torque,Claim 7 or claim 8The same effect can be achieved.
[0044]
  Claim 13If the brushless DC motor driving apparatus is used, a brushless DC motor having a 3 × N (N is an even number) slot stator and a 2 × N pole rotor is employed, and harmonic component current injection means, In place of the harmonic current injection means, N × K (K is an integer equal to or greater than 1) order harmonic noise is injected to inject current including harmonic currents of orders other than N × K ± first order. By adopting the means, by applying it to a brushless DC motor having a stator with 3 × N slots and a rotor with 2 × N poles,Claim 12The same effect can be achieved.
[0045]
  Claim 14The brushless DC motor driving apparatus employs a brushless DC motor having a 6-slot stator and a 4-pole rotor, and the current injection means is 2K (K is an integer of 1 or more) In order to reduce the harmonic noise of the brushless DC motor having a 6-slot stator and a 4-pole rotor, a motor that injects a current including a harmonic current of an order other than 2K ± 1 is adopted. By applyingClaim 13The same effect can be achieved.
[0046]
  Claim 15In this case, the rotational position of the rotor of the brushless DC motor is detected from the motor neutral point signal, and the drive current is supplied from the power supply device to the brushless DC motor based on the detected rotational position. Since it further includes power control means for controlling the power supply device, it can be applied to applications where it is difficult to wear a position detection sensor,Claims 7 to 14The same action as any of the above can be achieved.
[0047]
  Claim 16In the case of the brushless DC motor driving apparatus, the rotational position of the brushless DC motor rotor is detected from the stator applied voltage of the brushless DC motor, the motor current, and the device constants of the brushless DC motor, and based on the detected rotational position. In addition to power supply control means for controlling the power supply device to supply drive current from the power supply device to the brushless DC motor, it can be applied to applications where it is difficult to mount the position detection sensor.Claims 7 to 14The same action as any of the above can be achieved.
[0048]
  Claim 17In the case of the brushless DC motor driving apparatus, since the brushless DC motor that drives the compressor for the refrigeration apparatus or the compressor for the air conditioner is adopted, the compression is caused by the electromagnetic force of the brushless DC motor. In addition to greatly reducing the noise generated from the machine,Claims 7 to 16The same action as any of the above can be achieved.
[0049]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a brushless DC motor driving method and apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.
[0050]
FIG. 1 is a schematic view showing an embodiment of the brushless DC motor driving apparatus of the present invention.
[0051]
The brushless DC motor driving device includes a power source device 1 including a DC power source 1a and a three-phase inverter circuit 1b, a brushless DC motor 2 to which a driving current is supplied from the three-phase inverter circuit 1b, and a driving current for two phases. The sensorless position detection circuit 3 for detecting the rotational position of the rotor of the brushless DC motor 2 as input and the position detection signal output from the sensorless position detection circuit 3 are used as input to perform PWM control calculation, and the three-phase inverter circuit 1b is PWMed. A PWM generation circuit 4 that outputs a PWM control signal to be operated, and a harmonic injection circuit 5 that injects a harmonic component current using the position detection signal output from the sensorless position detection circuit 3 as an input.
[0052]
A sensor that detects a rotational position using a sensor such as a rotary encoder instead of the sensorless position detection circuit 3, a sensor that detects an induced voltage of the brushless DC motor 2 and detects a rotational position from the detected voltage, a brushless DC It is possible to employ one that detects the rotational position by performing an operation using the drive current and voltage of the motor 2.
[0053]
The three-phase inverter circuit 1b switches the energization of the brushless DC motor 2 by switching the energization of the brushless DC motor 2 by switching the DC voltage with the switching element and applying it to the brushless DC motor 2 and detecting the rotational position of the rotor by the position detection signal. PWM control is performed to drive the brushless DC motor 2.
[0054]
The PWM generation circuit 4 receives a position detection signal, outputs a PWM control signal to cause the three-phase inverter circuit 1b to perform PWM operation based on the position detection signal, and supplies the PWM control signal to the switching element of the three-phase inverter circuit 1b. is there.
[0055]
The harmonic injection circuit 5 has a single or a plurality of orders that do not necessarily include the harmonic component of the corresponding order and the corresponding order ± 1st order harmonic component with respect to the harmonic noise component of the order to be reduced. The motor current of the higher harmonic component is injected. Here, the primary component is a fundamental frequency component that drives the brushless DC motor. Therefore, the harmonic injection circuit 5 can inject the motor current of the harmonic component of the above order in response to the setting of the order of the harmonic vibration component to be reduced.
[0056]
The operation of the brushless DC motor driving apparatus having the above-described configuration is as follows.
[0057]
The rotational position of the rotor of the brushless DC motor 2 is detected by a sensorless position detection circuit 3, and a PWM control signal is generated by a PWM generation circuit 4 that receives a position detection signal from the sensorless position detection circuit 3 to generate a three-phase inverter circuit. In controlling the drive current supplied to 1b and supplied to the brushless DC motor 2, a harmonic current component of an order not directly related to the harmonic noise component to be reduced is injected from the harmonic injection circuit 5 This signal can be supplied to the PWM generation circuit 4, and the noise and vibration of the brushless DC motor 2 can be reliably and sufficiently reduced by the injected harmonic current component.
[0058]
Further explanation will be given.
[0059]
Regarding the relationship between the electromagnetic force and noise of the brushless DC motor, the frequency component of the electromagnetic force of the brushless DC motor 2 does not depend on the number of poles, and depends on the frequency of the drive current (or drive voltage) 2 × n times. (Refer to FIG. 2, where f is the fundamental frequency of the drive frequency), and a harmonic component depending on the motor shape is superimposed on this. For example, when there are 12 stator slots per station, 12 × K order harmonic components are superimposed. Here, n and K are positive integers.
[0060]
These harmonic components become vibration and noise and are radiated from the brushless DC motor.
[0061]
Then, for example, by using a sinusoidal PWM waveform and injecting a current of a fifth-order harmonic component into the first-order component of the fundamental wave, as shown in FIG. Wave noise components can be reduced. Here, if the fifth-order harmonic current component is increased, the tenth-order harmonic noise component can be reduced by 2.5 dBA.
[0062]
Conventionally, in order to reduce the 10th-order harmonic noise component, it has been thought that a 10th-order ± 1st-order harmonic current component may be injected. However, it was found that when only the 11th harmonic current component was injected, the 10th harmonic noise component increased as shown in FIG. This is presumably because the eleventh order ± first order motor electromagnetic force directly contributes to noise, and as a result, the tenth order harmonic noise component increases.
[0063]
Further, by using a sine wave PWM waveform and injecting currents of the fifth and seventh harmonic components to the fundamental component of the fundamental wave, as shown in FIG. Harmonic noise components can be reduced. Here, if the fifth and seventh harmonic current components are increased, the eighth harmonic noise component can be reduced by 5 dBA.
[0064]
When only the fifth-order or seventh-order harmonic current component is injected, the eighth-order harmonic noise component does not decrease or increases, as shown in FIGS. 4B and 4C. I understand that. This is because the fifth-order harmonic current component does not directly contribute to the eighth-order harmonic noise component, and as a result, the eighth-order harmonic noise component does not decrease. This is because the force directly contributes to the noise, and as a result, the 8th harmonic noise component increases.
[0065]
In other words, injecting the harmonic current component of the order in which the motor electromagnetic force directly contributes to the noise to the harmonic noise component of the order to be reduced tends to increase the noise.
[0066]
3 and 4, the horizontal axis represents the harmonic current ratio (= each harmonic current component / fundamental current component), and the vertical axis represents the 10f sound (10th harmonic noise component) and 8f sound ( 8th harmonic noise component).
[0067]
Furthermore, if a seventh-order harmonic current component is injected by the harmonic injection circuit 5, the 14th-order harmonic noise component can be significantly reduced (up to 15 dBA). Here, as shown in FIG. 5, the 14th harmonic noise component changes according to the 7th harmonic current ratio, so the 7th harmonic current ratio is set to 0.05 to 0.20. What is necessary is just to set to 0.10-0.15.
[0068]
The 14th harmonic noise component is reduced because the 14th harmonic noise component is particularly large as a result of measuring the noise spectrum during compressor operation. This is because the noise of the entire compressor can be reduced.
[0069]
The brushless DC motor 2 is broadly classified into one having a permanent magnet mounted on the rotor surface (see FIG. 7) and one having a permanent magnet embedded in the rotor (see FIG. 8). . Among these, when the brushless DC motor having the latter configuration is adopted, the electromagnetic force is likely to concentrate on a part of the rotor surface, so that the vibration and noise of the brushless DC motor increase. Therefore, the effect of reducing the harmonic excitation force component is further increased by injecting a single or a plurality of orders of harmonic component motor current.
[0070]
When the brushless DC motor having the latter configuration is adopted, not only the magnet torque by the permanent magnet but also the reluctance torque using the magnetic flux flowing through the iron core on the rotor surface can be used together.
[0071]
Therefore, the brushless DC motor 2 can be driven with low vibration / low noise and high torque. In other words, a high load can be driven with low vibration and low noise.
[0072]
The brushless DC motor 2 is broadly classified into one in which windings are distributed around the teeth of the stator (see FIG. 9) and one in which winding is concentrated (see FIG. 10). Among these, when the brushless DC motor having the latter configuration is adopted, the winding is directly wound around the tooth portion, so that the winding resistance is reduced and the copper loss is reduced as compared with the stator with distributed winding. High efficiency. However, since the winding is concentrated on one stator tooth portion, the electromagnetic force is also concentrated, resulting in an increase in noise and vibration. Therefore, the effect of reducing the harmonic excitation force component is further increased by injecting a single or a plurality of orders of harmonic current motor current.
[0073]
Therefore, when the brushless DC motor having the latter configuration is employed, the brushless DC motor can be driven with high efficiency and low noise.
[0074]
In the concentrated winding brushless DC motor, it is possible to set the number of stator slots to 3 × N (N is an even number) and the number of rotor poles to 2 × N. In this case, N × K (K is an integer greater than or equal to 1) order harmonic noise is reduced by injecting a current containing harmonic current components other than N × K ± 1st order, with high efficiency and low noise. A brushless DC motor can be driven.
[0075]
Specifically, the number of slots of the stator is set to 6 and the number of poles of the rotor is set to 4, so that harmonic current components other than 2 × K ± 1st order are reduced in order to reduce 2 × K order harmonic noise. By injecting the contained current, the brushless DC motor can be driven with high efficiency and low noise.
[0076]
FIG. 11 is an electric circuit diagram showing an example of the configuration of the sensorless position detection circuit 3.
[0077]
This sensorless position detection circuit 3 connects a Y-connected resistor 2b in parallel with a Y-connected stator winding 2a, and a neutral point voltage V of the stator winding 2a._NAnd neutral point voltage V of resistor 2b_MAre input to the differential amplifier 3a, the integrator 3b to which the output signal from the differential amplifier 3a is input, and the zero cross comparator 3c to which the output signal from the integrator 3b is input (Japanese Patent Laid-Open No. Hei 7). -337079). The output signal from the zero cross comparator 3c is a position detection signal.
[0078]
In FIG. 11, the microcomputer 6 can achieve the functions of the PWM generation circuit 4 and the harmonic injection circuit 5 as well as other conventionally known functions. The base drive circuit 7 receives a switching signal output from the microcomputer 6 and outputs a signal that can actually switch the switching element.
[0079]
When the sensorless position detection circuit 3 having the above configuration is adopted, the position detection is performed based on the potential fluctuation at the neutral point of the motor, so that it is not affected by the energization period applied to the brushless DC motor, and in principle. Can detect the position of all 180 ° sections, and can control all phases of 180 °.
[0080]
In addition, when the brushless DC motor is used in a high temperature / high pressure environment or the like, a sensor is not necessary, and therefore the brushless DC motor can be driven without any inconvenience by detecting the motor position with high reliability at low cost.
[0081]
Furthermore, since it is not necessary to limit the energization period of the current supplied to the brushless DC motor, sine wave energization is possible, which can contribute to higher efficiency of the brushless DC motor.
[0082]
Furthermore, since the current phase can be controlled freely, it is possible to use both the magnet torque and the reluctance torque, and it is possible to drive the motor more efficiently and to control the magnetic flux weakening. Expansion of the operating range can be achieved.
[0083]
FIG. 12 is a block diagram showing another example of the configuration of the sensorless position detection circuit 3. FIG. 12 also shows a portion for controlling the three-phase inverter circuit 2.
[0084]
The sensorless position detection circuit 3 receives a motor current and a motor voltage as input, a current detector 31 that detects a motor current, a voltage detector 32 that detects a motor voltage, and rotates using an internal motor model. Position / speed detector 33 for outputting the rotational position of the rotor and the rotational speed of the rotor, and a speed controller for performing a speed control calculation with the speed command given from the outside and the output rotational speed as inputs, and outputting a current command 34, a phase control unit 35 that performs a phase control calculation with an externally supplied phase command and current command as input, and an output signal from the phase control unit 35, a motor current, and a rotational position of the rotor as an input for current control calculation. And a current control unit 36 that outputs a voltage command and supplies the voltage command to the three-phase inverter circuit 1b.
[0085]
In FIG. 12, the AC power source 1a is constituted by the AC power source 1a1, the rectifier circuit 1a2, and the smoothing capacitor 1a3.
[0086]
When the sensorless position detection circuit 3 having the above configuration is employed, a mathematical model of the motor is used to rotate based on the estimated current calculated based on the estimated position and the estimated speed electromotive force and the actually flowing motor current. The rotation position of the rotor and the rotation speed of the rotor can be identified ("Sensorless brushless DC motor control based on current estimation error", Takeshita et al., T. IEEE Japan, Vol. 115-D, No. 4, '95. reference).
[0087]
In the case of a brushless DC motor with saliency, the winding inductance changes depending on the rotational position of the rotor, making it difficult to estimate the position. However, by expanding the mathematical model of the motor to a salient pole type motor, Position estimation is possible (refer to “Sensorless salient pole type brushless DC motor control based on velocity electromotive force estimation”, Takeshita et al., T. IEEE Japan, Vol. 117-D, No. 1, '97).
[0088]
This sensorless position detection circuit is not affected by the energization period applied to the brushless DC motor, and in principle can detect the position of all 180 ° sections, and can control all phases of 180 °.
[0089]
In addition, when the brushless DC motor is used in a high temperature / high pressure environment or the like, a sensor is not necessary, and therefore the brushless DC motor can be driven without any inconvenience by detecting the motor position with high reliability at low cost.
[0090]
Furthermore, since it is not necessary to sine the energization period of the current supplied to the brushless DC motor, sine wave energization is possible, which can contribute to higher efficiency of the brushless DC motor.
[0091]
Furthermore, since the current phase can be controlled freely, it is possible to use both the magnet torque and the reluctance torque, and it is possible to drive the motor more efficiently and to control the magnetic flux weakening. Expansion of the operating range can be achieved.
[0092]
Furthermore, since it is possible in principle to estimate the position instantaneously during motor operation, it is possible to inject an accurate harmonic current, and to achieve further reduction in vibration and noise.
[0093]
Consider a case in which a compressor for a refrigerator or a compressor for an air conditioner is driven by a brushless DC motor driven as described above.
[0094]
A compressor for a refrigerator or a compressor for an air conditioner is composed of various members, and the natural frequency of those members causes resonance with the harmonic component of the electromagnetic force of the brushless DC motor, resulting in large noise ( A protruding sound) is generated. However, by driving the brushless DC motor using the above embodiment, the noise generated from the compressor due to the electromagnetic force of the brushless DC motor can be greatly reduced.
[0095]
Specifically, when driving a compressor in which a 14th-order harmonic noise component is generated as shown in FIG. 13, by injecting a 7th-order harmonic current component and driving a brushless DC motor, As shown in FIG. 14, the 14th harmonic noise component can be significantly reduced.
[0097]
【The invention's effect】
  Claim 1The present invention has a unique effect that the effect of reducing electromagnetic force vibration and noise can be enhanced.
[0098]
  Claim 2The invention ofClaim 1Has the same effect as.
[0099]
  Claim 3The invention has a characteristic effect that the 14th-order noise component can be greatly reduced.
[0100]
  Claim 4The invention ofClaim 3Has the same effect as.
[0101]
  Claim 5The present invention can be applied to applications where it is difficult to mount the position detection sensor.Claim 4The same effect as any of the above.
[0102]
  Claim 6The present invention can be applied to applications where it is difficult to mount the position detection sensor.Claim 4The same effect as any of the above.
[0104]
  Claim 7The present invention has a unique effect that the effect of reducing electromagnetic force vibration and noise can be enhanced.
[0105]
  Claim 8The invention ofClaim 7Has the same effect as.
[0106]
  Claim 9The invention has a characteristic effect that the 14th-order noise component can be greatly reduced.
[0107]
  Claim 10The invention ofClaim 9Has the same effect as.
[0108]
  Claim 11In addition to being able to achieve low vibration, low noise and high torque,Claims 7 to 10The same effect as any of the above.
[0109]
  Claim 12In addition to being able to achieve low vibration, low noise and high torque,Claim 7 or claim 8Has the same effect as.
[0110]
  Claim 13By applying the invention to a brushless DC motor having a 3 × N slot stator and a 2 × N pole rotor,Claim 12Has the same effect as.
[0111]
  Claim 14By applying the invention to a brushless DC motor having a 6-slot stator and a 4-pole rotor,Claim 13Has the same effect as.
[0112]
  Claim 15In addition to being applicable to applications where it is difficult to wear a position detection sensor,Claims 7 to 14The same effect as any of the above.
[0113]
  Claim 16In addition to being applicable to applications where it is difficult to wear a position detection sensor,Claims 7 to 14The same effect as any of the above.
[0114]
  Claim 19In addition to greatly reducing noise generated from the compressor due to the electromagnetic force of the brushless DC motor,Claims 7 to 16The same effect as any of the above.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an embodiment of a brushless DC motor driving apparatus according to the present invention.
FIG. 2 is a diagram illustrating harmonic components of electromagnetic force generated in a brushless DC motor.
FIG. 3 is a diagram showing a change of a 10th harmonic vibration component with respect to a harmonic current ratio of the 5th and 11th harmonic currents.
FIG. 4 is a diagram illustrating a change in an eighth-order harmonic vibration component with respect to a harmonic current ratio of the fifth-order, seventh-order harmonic current, fifth-order, and seventh-order harmonic current;
FIG. 5 is a diagram showing a change of a 14th harmonic vibration component with respect to a harmonic current ratio of a 7th harmonic current.
FIG. 6 is a diagram illustrating an example of a noise spectrum during compressor operation.
FIG. 7 is a diagram showing a configuration and an electromagnetic force vector of a brushless DC motor having a surface magnet structure.
FIG. 8 is a diagram showing a configuration and an electromagnetic force vector of a brushless DC motor having an embedded magnet structure.
FIG. 9 is a diagram showing an electromagnetic force vector distribution of a distributed winding brushless DC motor.
FIG. 10 is a diagram showing an electromagnetic force vector distribution of a concentrated winding brushless DC motor.
FIG. 11 is an electric circuit diagram showing a sensorless position detection circuit using a motor neutral point signal.
FIG. 12 is a block diagram showing a sensorless position detection circuit using a mathematical model of a motor.
FIG. 13 is a diagram showing a noise spectrum of a compressor when no seventh harmonic current is injected.
FIG. 14 is a diagram showing a noise spectrum of a compressor when a seventh harmonic current is injected.
[Explanation of symbols]
1b Three-phase inverter circuit 2 Brushless DC motor
3a differential amplifier 3b integrator
3c Zero cross comparator 6 Microcomputer
5 Harmonic injection circuit 33 Position / speed detector
34 Speed control unit 35 Position control unit
36 Power control unit

Claims (17)

  A method of driving a brushless DC motor (2) by supplying a drive current from a power supply device (1b), wherein a harmonic current of a different order is injected into a drive current including a harmonic component of a predetermined order. A method for driving a brushless DC motor. The brushless DC motor driving method according to claim 1 , wherein the order of the harmonic current to be injected is at least one order.   A method of driving a brushless DC motor (2) by supplying a driving current from a power supply device (1b), wherein a brushless DC motor is injected with a seventh harmonic current of a fundamental wave to the driving current. DC motor drive method. 4. The brushless DC motor driving method according to claim 3 , wherein an amount of the seventh harmonic current to be injected is set to 0.05 to 0.20 times the fundamental wave. The rotational position of the rotor of the brushless DC motor (2) is detected from the motor neutral point signal, and a drive current is supplied from the power supply device (1b) to the brushless DC motor (2) based on the detected rotational position. The brushless DC motor drive method according to any one of claims 1 to 4 . The rotational position of the rotor of the brushless DC motor (2) is detected from the stator applied voltage of the brushless DC motor (2), the motor current, and the device constants of the brushless DC motor (2), and based on the detected rotational position. The brushless DC motor drive method according to any one of claims 1 to 4 , wherein a drive current is supplied from the power supply device (1b) to the brushless DC motor (2).   A device that drives the brushless DC motor (2) by supplying a drive current from the power supply device (1b), and that injects harmonic currents of different orders into drive currents including harmonic components of a predetermined order. A brushless DC motor driving device comprising wave current injection means (5). The brushless DC motor driving device according to claim 7 , wherein the order of the harmonic current to be injected is at least one order.   A device for driving a brushless DC motor (2) by supplying a driving current from a power supply device (1b), and injecting a seventh harmonic current of a fundamental wave into the driving current. A brushless DC motor driving device comprising means (5). The brushless DC according to claim 9 , wherein the seventh harmonic current injection means (5) sets the amount of the seventh harmonic current injected to 0.05 to 0.20 times the fundamental wave. Motor drive device. The brushless DC motor drive device according to any one of claims 7 to 10 , wherein the brushless DC motor (2) has a rotor in which a permanent magnet is embedded. The brushless DC motor drive device according to any one of claims 7 and 8 , wherein the brushless DC motor (2) has a concentrated winding type stator formed by winding a winding directly around a tooth portion. The brushless DC motor (2) has a stator of 3 × N (N is an even number) slot and a rotor of 2 × N poles, and includes harmonic component current injection means (5), harmonic current injection means. In place of (5), current injection means for injecting a current including harmonic currents of orders other than N × K ± 1st order in order to reduce N × K (K is an integer of 1 or more) order harmonic noise ( The brushless DC motor driving device according to claim 12 , which employs 5). The brushless DC motor (2) has a 6-slot stator and a 4-pole rotor, and the current injection means (5) generates harmonic noise of the order of 2K (K is an integer of 1 or more). The brushless DC motor driving device according to claim 13 , wherein a device that injects a current including a harmonic current of an order other than the 2K ± 1st order is used for reduction. Power supply control that detects the rotational position of the rotor of the brushless DC motor from the motor neutral point signal and controls the power supply apparatus (1b) to supply a drive current from the power supply apparatus to the brushless DC motor based on the detected rotational position. The brushless DC motor driving device according to any one of claims 7 to 14 , further comprising means (3a) (3b) (3c) (6). The rotational position of the rotor of the brushless DC motor (2) is detected from the stator applied voltage of the brushless DC motor (2), the motor current, and the device constants of the brushless DC motor (2), and based on the detected rotational position. billing from the power supply (1b) a brushless DC motor power control means (33) for controlling power supplies (1b) to supply drive current to (2) (34) (35) (36) according to claim 7, further comprising a Item 15. The brushless DC motor drive device according to any one of Items 14 to 14 . The brushless DC motor drive device according to any one of claims 7 to 16 , wherein the brushless DC motor (2) drives a compressor for a refrigeration apparatus or a compressor for an air conditioner.

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