JP3541861B2 - DC brushless motor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a drive device for a DC brushless motor.
[0002]
[Prior art]
A DC brushless motor is a motor that electronically performs rectification of a DC motor and the role of a brush by means of an inverter or the like. The position of a magnetic pole of a rotor is detected by a Hall element attached to a stator. The excitation pattern is formed so that the torque between them becomes maximum.
[0003]
FIG. 7 is a schematic configuration diagram of a conventional DC brushless motor, in which a rotor 1 having four magnetic poles and a stator 4 having three-phase excitation coils 2 are provided. In this DC brushless motor, three Hall elements 3A, 3B, 3C are arranged on a stator 4 at 120-degree intervals (or 60-degree intervals), and a Hall element signal from each Hall element is sent to an inverter 5, and this inverter 5 Generates a drive signal using the Hall element signal, and drives each excitation coil 2.
[0004]
FIG. 8 is a schematic block diagram illustrating the configuration of the motor and the inverter. The motor shown in FIG. 8 includes three-phase excitation coils U, V, and W and three Hall elements 3A, 3B, and 3C. The inverter 5 receives a Hall element signal and outputs a Hall element detection signal. A signal detection unit 51, an excitation pattern formation unit 54 that forms an excitation pattern based on the Hall element detection signal, and a drive signal formation unit 56 that forms a drive signal according to the excitation pattern are provided.
[0005]
FIG. 9 is a diagram for explaining the relationship between the Hall element detection signal and the excitation pattern. In FIG. 9, when the rotor rotates, the Hall elements 3A, 3B and 3C detect Hall element signals whose phases are shifted according to the rotor position. The phase shift angle is determined according to the arrangement interval of the Hall elements 3A, 3B, 3C. The Hall element signal detecting means 51 in the inverter 5 forms Hall element detection signals A, B and C from the Hall element signals. The excitation pattern forming means 54 forms an excitation pattern based on the Hall element detection signal so that a magnetic flux having the polarity shown in FIG. The excitation coils U, V, W drive the rotor by switching the excitation at the timings (1) to (6) in the figure.
[0006]
[Problems to be solved by the invention]
However, the conventional DC brushless motor has a problem in detecting the rotor position. In a conventional DC brushless motor, in order to detect a rotor position, a Hall element is arranged corresponding to an exciting coil of each phase, and a magnetic pole position of the rotor with respect to each exciting coil is detected by each Hall element. I have. Therefore, it is necessary to incorporate a plurality of Hall elements into the motor, and it is necessary to arrange these Hall elements at equal intervals. For this reason, there are disadvantages in that the number of components increases, and assembly accuracy for arranging them at equal intervals is required. Further, since all the detection signals of the Hall elements arranged in the motor are taken into the inverter, there is a disadvantage that the number of signal lines installed between the motor and the inverter increases.
[0007]
Therefore, an object of the present invention is to solve the above-described problems of the conventional DC brushless motor, and to provide a DC brushless motor that can detect the rotor position with one detection element and drive the motor. I do.
[0008]
[Means for Solving the Problems]
The present invention provides a DC brushless motor having a rotor having magnetic poles and a stator having exciting coils of each phase, wherein one rotor position detecting means is provided on the stator side, and one detection signal of the rotor position detecting means is provided. The above object is achieved by providing excitation pattern forming means for forming an excitation pattern for driving the excitation coil of each phase by using.
[0009]
In the DC brushless motor of the present invention, when the rotor rotates, the rotor position detecting means detects a change in magnetic pole due to the magnetic pole of the rotor and outputs a detection signal. This detection signal indicates the magnetic pole position of the rotor with respect to the exciting coil in which the rotor position detecting means is installed. The excitation pattern forming means uses one detection signal from the rotor position detection means to predict the magnetic pole position of the rotor with respect to the excitation coil in which the rotor position detection means is not installed, and determines the excitation coils of each phase of the motor. An excitation pattern to be driven is formed. The DC brushless motor drives the rotor by exciting the exciting coil according to the formed excitation pattern.
[0010]
In the first embodiment of the present invention, the rotor position detecting means includes a Hall element, and a change in magnetic pole caused by the magnetic pole of the rotor can be detected by a Hall element or a Hall IC to detect the rotor position.
In a second embodiment of the present invention, the excitation pattern forming means predicts and forms a pseudo signal representing the rotor position with respect to the exciting coil of each phase from one detection signal output from the rotor position detecting means, Thus, a signal representing the rotor position with respect to the exciting coil of each phase can be obtained by one rotor position detecting means.
[0011]
According to a third embodiment of the present invention, the excitation pattern forming means uses one detection signal output from the rotor position detecting means, and the signal length of the detection signal in the next cycle from the signal length one cycle before the detection signal. A pseudo signal is formed by predicting the phase and the phase, and the pseudo signal is used as a signal representing the rotor position with respect to the excitation coil of each phase. Can be obtained.
[0012]
The fourth embodiment of the present invention is provided with a starting excitation pattern forming unit. By supplying the starting excitation pattern to the excitation coil, the starting of the rotor without using the excitation pattern from the excitation pattern forming unit is performed. It can be performed. In a fifth embodiment of the present invention, the starting excitation pattern forming means forms an excitation pattern in which the excitation interval is gradually shortened, whereby the rotor can be started regardless of the rotor position.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
A configuration example of an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram illustrating a configuration of a DC brushless motor according to an embodiment of the present invention, and illustrates configurations of a motor and an inverter. In FIG. 1, the motor shown includes three-phase excitation coils U, V, and W and one rotor position detecting means 3. In the following description, a Hall element will be described as an example of the rotor position detecting means 3, but a means for detecting a change in magnetic pole such as a Hall IC can be used instead of the Hall element.
[0014]
Further, the inverter 5 receives a Hall element signal and outputs a Hall element detection signal, a Hall element signal detection means 51, a timer means 52 for measuring a periodic interval of the Hall element detection signal, and a starter for starting a stationary rotor. Starting pattern forming means 53 for forming the excitation pattern of the above, excitation pattern forming means 54 for forming the excitation pattern by the Hall element detection signal and the pseudo signal, and the starting excitation pattern and the starting excitation pattern from the starting excitation pattern forming means 53. An excitation pattern selecting unit 55 for selecting an excitation pattern from the pattern forming unit 54 and a drive signal forming unit 56 for forming a drive signal according to the selected excitation pattern are provided. Incidentally, each means such as the timer means 52, the starting excitation pattern forming means 53, the excitation pattern forming means 54, and the excitation pattern selecting means 55 can be selectively provided in the microcomputer as needed.
[0015]
FIG. 2 is a diagram for explaining the arrangement of the rotor position detecting means in the motor. The configuration of the motor shown in FIG. 2 is an example including a rotor 1 having four magnetic poles and a stator 4 having three-phase excitation coils 2 as in FIG. In the DC brushless motor of the present invention, one Hall element 3 is disposed on the stator 2 as a rotor position detecting means, and a Hall element signal from the Hall element 3 is sent to the inverter 5, and the inverter 5 uses the Hall element signal. A drive signal is formed to drive the excitation coil 2 of each phase.
[0016]
FIG. 3 is a diagram for explaining the relationship among the Hall element detection signal, the pseudo signal, and the excitation pattern. 1, 2 and 3, when the rotor rotates, the Hall element 3 detects a Hall element signal according to the rotor position and sends it to the Hall element signal detection means 51 in the inverter 5. The Hall element signal detection means 51 performs a waveform processing on the Hall element signal to form a Hall element detection signal, which is sent to the timer means 52 and the starting excitation pattern forming means 53.
[0017]
The Hall element signal formed by the Hall element signal detecting means 51 detects only a magnetic pole change with respect to the exciting coil in which the Hall element 3 is installed, and does not detect a magnetic pole change with respect to the exciting coil in which other Hall elements are not installed. . Therefore, in the present invention, a signal not detected by the timer means 52 is predicted to form a pseudo signal.
[0018]
The timer means 52 measures the period interval of the Hall element detection signal, and measures the time interval during which the N and S poles of the rotor are detected. This time interval is output, for example, as a count value counted within the time interval. The period interval of the Hall element detection signal obtained by the timer means 52 is a magnetic pole change with respect to the exciting coil in which the Hall element 3 is installed, and the magnetic pole change with respect to the exciting coil in which other Hall elements are not installed is not measured. Therefore, the timer means 52 predicts a Hall element detection signal that is not actually measured based on the obtained period interval of the Hall element detection signal, and forms the pseudo signals a, b, and c. The pseudo signal a can use the Hall element detection signal itself.
[0019]
The excitation pattern creating means 54 forms an excitation pattern based on the pseudo signals a, b, and c so that a magnetic flux having a polarity as shown in FIG. 3 is formed at the rotor position. The excitation coils U, V, W drive the rotor by switching the excitation at the timings (1) to (6) in the figure.
[0020]
In the embodiment of the present invention, the starting excitation pattern forming means 53 is a means for forming an excitation pattern for starting the rotor from a stationary state. The excitation pattern for starting and the excitation pattern from the excitation pattern forming means 54 are selected by the excitation pattern selecting means 55 and sent to the drive signal forming means 56. The drive signal forming means 56 forms a drive signal in accordance with the transmitted excitation pattern, and supplies an excitation current to the excitation coil 2 of each phase to perform driving.
[0021]
Next, the operation of the DC brushless motor of the present invention will be described. 4 is a flowchart for explaining the operation of the DC brushless motor of the present invention, FIG. 5 is a diagram for explaining the operation at the time of starting, and FIG. 6 is a diagram for explaining the operation after the starting.
First, the motor is started by driving the exciting coil according to the starting excitation pattern. At this time, the excitation pattern selecting means 55 receives the excitation pattern selection signal from the starting excitation pattern forming means 53, selects the starting excitation pattern from the starting excitation pattern forming means 53, and sends it to the drive signal forming means 56. As shown in FIG. 5, the excitation pattern for starting can be constituted by an excitation pattern in which the excitation interval gradually becomes shorter. In FIG. 5, the excitation interval is formed shorter in order from TA to TD. This starting excitation pattern is supplied to the excitation coil regardless of the rotor position. DC brushless motors are basically driven by synchronous driving, but can be driven asynchronously at low speeds, and by exciting with a starting excitation pattern that gradually changes from a long excitation interval to a short excitation interval. The rotation of the rotor can be started. The start of the rotor can be confirmed by the fact that the pulse length Tn counted by the timer means 52 has become shorter than a predetermined value T0 (steps S1, S2).
[0022]
After the rotor starts rotating, a change in the Hall element signal is detected (step S3), and a timer is started. For example, when the Hall element signal is S depending on the rotor position at rest, the timer is started when the Hall element detection signal changes from S to N, and pulse counting is started (step S4).
[0023]
Next, a point in time when the signal of the Hall element changes is detected, and a cycle in this section is obtained as a pulse length. In the case of FIG. 6, the time when the Hall element detection signal changes from N to S is detected (step S5). At this point, the pseudo signals a, b, and c are initialized. The initialization of the pseudo signal at this time can be performed by turning off the pseudo signal a, turning on the pseudo signal b, and turning off the pseudo signal c (step S6). Further, the pulse length Ta counted by the timer at the time of step S5 is obtained. This pulse length Ta is a cycle interval in a cycle before initialization. After acquiring the pulse length, the timer starts measuring the current cycle interval by resetting or the like (step S7).
[0024]
If the change of the Hall element signal at this time is from N to S, a pseudo signal is sequentially formed by the processing of the following steps S9 to S12. If the change of the Hall element signal is from S to N, the following steps are performed. A pseudo signal is sequentially formed by the processing of S9, step S14, step S11, and step S15 (step S8).
[0025]
In FIG. 6, since the change of the Hall element signal is from N to S, the time Ta / 3 of 1/3 of the previously obtained pulse length Ta elapses, and the pseudo signal c is turned on at this elapse time. (Step S10). Further, the pseudo signal b is turned off after the elapse of Ta / 3 time from the elapse of the Ta / 3 time, that is, after the elapse of 2Ta / 3 time from the initialization time. Thereby, the pseudo signals b and c in the section where the Hall element detection signal is S can be formed (steps S11 and S12).
[0026]
Next, a change in the Hall element signal is detected. Since the Hall element detection signal that is currently being detected is S, the time point at which it becomes N is detected (step S13). When the Hall element detection signal changes from S to N, the process returns to step S7 to acquire the pulse length Tb representing the cycle interval (step S7). At this time, since the change of the Hall element signal changes from S to N (step S8), the time Tb / 3, which is 1/3 of the acquired pulse length Tb, elapses, and the pseudo signal c is turned off at this time (step S14). The pseudo signal b is turned on after a lapse of Tb / 3 from the lapse of Tb / 3, that is, after a lapse of 2Tb / 3 from the time when the Hall element detection signal changes from S to N. As a result, the pseudo signals b and c in the section where the Hall element detection signal is N can be formed (steps S11 and S15).
[0027]
Hereinafter, a pseudo signal in the next cycle is formed based on the previous cycle interval in order, and the excitation pattern is formed based on the pseudo signal.
According to the above-described embodiment, a pseudo signal indicating the rotor position corresponding to the exciting coil of each phase can be obtained by one rotor position detecting means. In addition, the motor can be started by the starting excitation pattern, and further, the switching between the starting excitation pattern and the excitation pattern based on the pseudo signal can be performed.
[0028]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a DC brushless motor capable of detecting a rotor position with one detection element and driving the motor.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of an embodiment of a DC brushless motor of the present invention.
FIG. 2 is a diagram illustrating an arrangement of a rotor position detecting means of the present invention in a motor.
FIG. 3 is a diagram illustrating a relationship among a hall element detection signal, a pseudo signal, and an excitation pattern according to the present invention.
FIG. 4 is a flowchart for explaining the operation of the DC brushless motor of the present invention.
FIG. 5 is a diagram illustrating the operation of the DC brushless motor according to the present invention at the time of starting.
FIG. 6 is a diagram illustrating the operation of the DC brushless motor of the present invention after starting.
FIG. 7 is a schematic configuration diagram of a conventional DC brushless motor.
FIG. 8 is a schematic block diagram illustrating a configuration of a motor and an inverter of a conventional DC brushless motor.
FIG. 9 is a diagram illustrating a relationship between a Hall element detection signal and an excitation pattern of a conventional DC brushless motor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Rotor, 2 ... Exciting coil, 3 ... Hall element (rotor position detecting means), 4 ... Stator, 5 ... Inverter, 51 ... Hall element signal detecting means, 52 ... Timer means, 53 ... Starting excitation pattern forming means, 54: excitation pattern forming means, 55 excitation pattern selecting means, 56: drive signal forming means.

Claims (1)

In a DC brushless motor including a rotor having magnetic poles and a stator having excitation coils of each phase,
One rotor position detecting means for forming a magnetic pole change of the rotor;
Starting excitation pattern forming means for forming an excitation pattern for starting the rotor from a stationary state,
Excitation pattern forming means for forming an excitation pattern for driving an excitation coil of each phase using one detection signal of the rotor position detection means;
Excitation pattern selection means,
The starting excitation pattern forming means forms a starting excitation pattern that gradually shortens the excitation interval,
The excitation pattern forming means forms a pseudo signal by predicting the signal length and phase of a detection signal of the next cycle from the signal length of one detection signal output from the rotor position detection means one cycle before, and forms the pseudo signal. Is formed in each phase as a signal representing the rotor position with respect to the exciting coil,
The DC brushless motor according to claim 1, wherein said selecting means switches from the starting excitation pattern to the excitation pattern after confirming the start of the rotor.

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