JP2007166769A - Method and apparatus for driving and controlling brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively achieve rotation control for quickly responding with respect to fluctuations in rotation. <P>SOLUTION: A predetermined time Ts is counted repeatedly by five timer counters 1-5 for starting for counting with timings shifted by a predetermined time α (S112, S122, S133, S142, S152). Zero-crossing points are detected, based on an output signal from a position detecting circuit 103. The number of the detected zero-crossing points is counted repeatedly within a predetermined counting time Ts of the timer-counters 1-5; and each time the timer counters 1-5 finish counting the predetermined time Ts, switching timing for a drive pulse signal is calculated, based on the number of the zero-crossing points detected within the predetermined counting time Ts (S118, S128, S138, S148, S158). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a brushless motor, and more particularly to an improvement in stability of drive current switching control.

  Conventionally, as this type of device, for example, a sensorless brushless motor including a rotor made of a permanent magnet and a fixed stator winding, and an induced voltage in the stator winding of the brushless motor. It is known and known that the rotor position can be controlled by detecting the rotor position and controlling the energization to the stator winding based on the detection result, thereby eliminating the need for a sensor for detecting the rotational position of the rotor. (For example, refer to Patent Document 1).

  In such a brushless motor, a so-called zero-crossing point, which is a point where the induced voltage induced in the stator winding in the drive current suspension state exceeds the reference voltage (for example, ground voltage) due to the polarity inversion, In general, the time interval of each zero cross point is measured, and the drive current switching timing is calculated and calculated from the measurement result, and the drive current switching control is generally performed.

Japanese Examined Patent Publication No. 6-42793 (page 2-4, FIGS. 1 to 4)

When the drive current switching timing is controlled as described above, each time a zero cross point is detected, the drive current switching timing is calculated based on the elapsed time from the previous zero cross point. It is ideal to calculate and switch the drive current based on the calculation result because it is possible to respond most rapidly to fluctuations in the rotational speed.
By the way, a microcomputer is generally used for such control, but it is not used only for controlling the switching timing of driving current close to real time as described above, but various other processes such as, for example, Usually, it is also used to execute processing such as calculation of duty during driving and determination of a zero cross point. Therefore, performing the switching control of the driving current near the real time (or the switching control of the output timing of the driving signal) while performing such other processing increases the burden on the microcomputer, and thus the processing capability is further increased. A high microcomputer is required, and as a result, the price of the apparatus is increased.

  Therefore, if the drive signal switching timing is obtained from the past detection results of a plurality of zero cross points, the burden on the microcomputer can be reduced, and a drive control device using a cheaper microcomputer can be provided. Although it is feasible, increasing the number of zero cross point detections will reduce the burden on the microcomputer, but it will determine the switching timing based on the old data in time series, and will rotate. There has been a problem in that the responsiveness is lowered when fluctuation occurs.

The present invention has been made in view of the above circumstances, and provides a drive control method and apparatus for a brushless motor capable of realizing rotation control with good responsiveness to rotation fluctuation at a relatively low cost.
Another object of the present invention is to provide a brushless motor drive control method and apparatus capable of realizing rotation control with good response to rotation fluctuations using an inexpensive microcomputer.

In order to achieve the above object of the present invention, a brushless motor drive control method according to the present invention comprises:
The duty of a drive pulse signal applied to the stator winding of the brushless motor is set based on the rotational position signal of the rotor of the brushless motor and the desired rotational speed, and the stator winding is set based on the rotational position signal of the rotor. A drive control method for a brushless motor configured to control the switching timing of the drive pulse signal to
While the counting of the second predetermined time is repeatedly performed by a plurality of timer counters whose counting start time is shifted every first predetermined time,
Detecting the zero cross point where the rotational position signal of the rotor exceeds a reference level, and repeatedly counting the number of times of detection of the zero cross point within the second predetermined time by the respective timer counters,
Each time the second predetermined time is counted by the plurality of timer counters, the switching timing of the drive pulse signal is determined based on the number of detections of the zero cross point within the second predetermined time. It is comprised so that it may do.
In order to achieve the above object of the present invention, a brushless motor drive control device according to the present invention comprises:
The duty of a drive pulse signal applied to the stator winding of the brushless motor is set based on the rotational position signal of the rotor of the brushless motor and the desired rotational speed, and the stator winding is set based on the rotational position signal of the rotor. A drive control device for a brushless motor configured to control the switching timing of the drive pulse signal to
A zero cross detecting means for detecting a zero cross point at which the rotational position signal of the rotor inputted externally exceeds a reference level;
Time counting means for repeatedly counting the second predetermined time by a plurality of timer counters whose counting start time is deviated every first predetermined time;
Zero cross counting means for counting the number of zero cross points detected by the zero cross detecting means within the second predetermined time by each timer counter in the time measuring means;
The driving pulse is calculated based on the count value of the zero cross point by the zero cross counting means within the second predetermined time every time the timer counter in the time counting means completes counting for the second predetermined time. Timing calculation means for calculating and calculating the signal switching timing.

  According to the present invention, the elapse of a predetermined time is repeatedly counted by a plurality of timer counters whose start time is shifted by a predetermined time, and every time the predetermined time is completed, Is configured so as to obtain the number of times that the zero crossing point at which the rotational position signal of the rotor exceeds the reference level is detected, so that each time measurement by each timer counter is completed, that is, at the start of counting. Since the rotation speed of the brushless motor can be obtained from a predetermined time and the number of detections of the zero crossing points between the predetermined time, which is the amount of deviation, the drive pulse signal obtained based on the rotation speed can be obtained. The switching timing can be updated every predetermined time. Therefore, it is possible to realize an appropriate real-time property for determining the switching timing of the drive pulse signal without drastically increasing the burden on the arithmetic processing of the control device, and the rotational control with good response to rotational fluctuation is relatively inexpensive. It has the effect that it can be realized.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 8.
The members and arrangements described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
First, a configuration example of a brushless motor drive control apparatus (hereinafter referred to as “this apparatus”) in which the brushless motor drive control method according to the embodiment of the present invention is executed will be described with reference to FIGS. 1 and 2. I will explain.

  The apparatus S includes a control unit (indicated as “CPU” in FIG. 1) 101, a drive circuit (indicated as “DRV” in FIG. 1) 102, and a position detection circuit (in FIG. 1, “SENS”). (Notation) 103 and are roughly divided.

The brushless motor 51 in the embodiment of the present invention is a so-called sensorless brushless motor having a known and well-known configuration, for example, rotational driving of a blower fan (not shown) of a blower in a vehicle air conditioner. It is used for. The position detection circuit 103 functions as a conventional sensor for detecting the rotational position of a rotor (not shown), and detects and controls the voltage induced in the stator windings 52a to 52c of the brushless motor 51. The unit 101 is configured to input at an appropriate level.
The control unit 101 uses a microcomputer having a known and well-known configuration, and various programs for controlling the drive of the brushless motor 51 in a storage area or storage element (not shown) in the microcomputer. Are stored, and they are executed as appropriate.

Specifically, the control unit 101 determines a rotor (not shown) position based on a detection signal from the position detection circuit 103, and determines the determined rotor position and a desired rotation speed signal input from the outside. Based on the above, a control signal for the drive circuit 102 that outputs a drive pulse signal to the stator windings 52a to 52c of the brushless motor 51 is generated and output. The drive control of the brushless motor 51 via the drive circuit 102 by the control unit 101 is specifically known and well-known so-called PWM (Pulse Width Modulation) control, depending on the desired number of rotations. The duty of the drive pulse signal output from the drive circuit 102 is determined, and the switching timing of the drive pulse signal is controlled according to the detection signal from the position detection circuit 103 to control energization to the stator windings 52a to 52c. It is to do.
Note that a known and well-known switching circuit is configured at the final stage of the drive circuit 102, and a drive pulse signal having a voltage value of the vehicle battery 1 is applied to the stator windings 52a to 52. Yes.

FIG. 2 shows a specific circuit configuration example of the position detection circuit 103. Hereinafter, the specific circuit configuration example will be described with reference to FIG.
This position detection circuit is mainly composed of three comparators 41a to 41c provided corresponding to the stator windings 52a to 52c and filter circuits 40a to 40c formed in front of the respective comparators 41a to 41c. It is configured as.
Each of the filter circuits 40a to 40c provided in the previous stage of each of the comparators 41a to 41c has basically the same configuration, and the configuration itself is a known and well-known configuration. Here, only the components are shown below, and the detailed description of the configuration is omitted.

That is, in the first filter circuit 40a, an integrating circuit is configured by the resistors 1a and 2a and the capacitor 4a, and in the second filter circuit 40b, an integrating circuit is configured by the resistors 1b and 2b and the capacitor 4b. In the third filter circuit 40c, an integrating circuit is constituted by the resistors 1c and 2c and the capacitor 4c.
In this configuration example, the first filter circuit 40a has an induced voltage of the U-phase stator winding 52a, and the second filter circuit 40b has an induced voltage of the V-phase stator winding 52b. The voltage is applied to the third filter circuit 40c by the induced voltage of the stator winding 52c in the W phase.

The output side of each of the filter circuits 40a to 40c, that is, the first filter circuit 40a, is the connection point between the resistors 1a and 2a and the capacitor 4a, and the second filter circuit 40b. Are the connection points of the resistors 1b and 2b and the capacitor 4b, and in the third filter circuit 40c, the connection points of the resistors 1c and 2c and the capacitor 4c are the corresponding comparators 41a to 41a, respectively. It is connected to the non-inverting input terminal 41c.
Further, resistors 3a, 3b, and 3c for setting a reference voltage in the comparison operation of the comparators 41a to 41c are connected between the inverting input terminals and the non-inverting input terminals of the comparators 41a to 41c, respectively. At the same time, the inverting input terminals of the comparators 41a to 41c are connected to each other and maintained at the same potential. For this reason, the comparators 41a to 41c detect points (zero cross points) where the output voltages of the filter circuits 40a to 40c pass a reference voltage (for example, zero potential).

Next, drive control executed by the control unit 101 will be described with reference to FIGS.
First, the drive control process according to the embodiment of the present invention will be briefly described. This drive control process is applied to the stator windings 52a to 52c by the drive circuit 102 in accordance with the control from the control unit 101. The drive pulse signal generation timing is determined according to the rotation state and is switched. Therefore, a plurality of timer counters that repeat counting for a predetermined time with the counting start timing shifted by a predetermined time, and in the embodiment of the present invention, counting for a predetermined time is repeatedly performed by five timer counters. Yes.

  On the other hand, a zero cross counter for counting the number of zero cross points detected via the position detection circuit 103 is provided corresponding to the five timer counters, and each of the zero counters during the predetermined time counting of the corresponding timer counter is provided. Counts the number of detections of cross points, and calculates and calculates the drive pulse signal switching timing based on the count value of the corresponding zero cross counter every time counting of the predetermined time in the corresponding timer counter is completed. Can be used for switching control of the drive pulse signal.

FIG. 7 shows a waveform diagram for explaining the relationship between the zero cross point detected by the position detection circuit 103 and the timing of the interrupt processing described below, which will be described below.
FIG. 7A shows an example of induced voltage (phase induced voltage) sequentially generated in the stator windings 52a to 52b to which no drive pulse signal is applied. In FIG. 7A, EU denotes the stator winding. The induced voltage in the line 52a, EV represents the induced voltage in the stator winding 52b, and EW represents the induced voltage in the stator winding 52c.

The filter circuits 40a to 40c have a delay characteristic, and the delay amount becomes a characteristic that increases as the rotation speed of the brushless motor 51 increases, in other words, the repetition amount of the input signal. The output signal has a phase delay of 90 degrees with respect to the input signal.
FIG. 7B shows output signals of the filter circuits 40a to 40c when the induced voltage shown in FIG. 7A is input. Each output signal has a phase delay Φs with respect to the input signal. Is output. For example, the point A of the V-phase induced voltage EV in FIG. 7A corresponds to the point A ′ in FIG. 7B, and the point B of the U-phase induced voltage EU in FIG. Corresponds to point B ′.
In the embodiment of the present invention, Φs is, for example, 60 degrees in electrical angle when the brushless motor 51 rotates at 1000 rpm.

  The output signals of the filter circuits 40a to 40c are used for comparison operations in the corresponding comparators 41a to 41c, respectively. As a result, the comparators 41a to 41c output the signals as shown in FIGS. 7C to 7E. Furthermore, while the output signals of the filter circuits 40a to 40c change from the positive electrode to the negative electrode and pass the virtual midpoint potential, the logic value Low changes to High, while the output signals of the filter circuits 40a to 40c change from the negative electrode to the positive electrode. However, when the virtual midpoint potential is passed, a signal that becomes High from the logical value Low is output.

  The output signals of the comparators 41a to 41c are those whose rising and falling edges are synchronized with the zero cross point of the induced voltage. In the control unit 101, the logical values of the input output signals of the comparators 41a to 41c. A rising edge from Low to High and a falling edge from the logical value High to Low are determined, and an interrupt timing for starting zero cross counter processing (to be described later) is set as a zero cross point when the rise or fall is determined (FIG. 7 (F ))).

Next, a specific procedure of the drive control process will be described with reference to the flowcharts shown in FIGS.
When the processing is started, the time counting by the five timer counters of the timer counter 1 to the timer counter 5 is started sequentially at a predetermined time α interval, and each time counting is executed (in FIG. 3). Steps S100 to S108).
Here, the timer counter 1 to the timer counter 5 are realized by executing software in the control unit 101. When the predetermined time Ts is counted, the counting from the zero to the predetermined time Ts is repeated again. . That is, as shown in FIG. 6, the timer counter 2 starts counting when a predetermined time α elapses after the timer counter 1 starts counting (FIG. 6A to FIG. 6). In the same manner, the timer counter 3 to the timer counter 5 start counting at a predetermined time α sequentially (see FIG. 6 (D)). To FIG. 6 (F))).
For example, as an example, Ts is 125 msec and α is 25 msec, but of course, it is not necessary to be limited to this value.

While these timer counter 1 to timer counter 5 are counting the predetermined time Ts, other processes are appropriately performed. For example, based on the output signal of the position detection circuit 103, generation of a basic control signal for the drive circuit 102, reading of a desired rotational speed from the outside, reading of the output signal of the position detection circuit 103, etc. are performed (FIG. 3 step S110).
Next, it is determined whether or not the count value of the timer counter 1 has reached the predetermined time Ts (see step S112 in FIG. 3). When it is determined that the count value has not yet reached the predetermined time Ts (in the case of NO) ), The process proceeds to step S122 described later. On the other hand, when it is determined that the count value has reached the predetermined time Ts (in the case of YES), the count value of the zero cross counter 1 at this time is a variable. A certain zero cross value is set (see step S114 in FIG. 3).

  Here, the zero cross counter 1 is provided corresponding to the timer counter 1, and as described above in the outline of the drive control processing in the embodiment of the present invention, the stator windings 52a to 52c. This is for counting the number of times that the induced voltage has passed zero. Corresponding zero cross counters 2 to 5 are also provided for timer counters 2 to 5.

The counting operation of the zero cross counters 1 to 5 is performed by the control unit 101 by determining the zero cross point from the output signal of the position detection circuit 103 as described above with reference to FIG. The zero cross counter process shown in FIG. 5 is executed as an interrupt process (see FIG. 7F).
Here, the zero cross counter process will be described with reference to FIG. 5. When the zero cross point is determined and the interrupt process is executed as described above, each of the zero cross counter 1 to the zero cross counter 5 is executed. Is incremented by 1 (counting up), and the zero cross count process is terminated (see steps S200 to S208 in FIG. 5).

  Here, returning to the description of FIG. 3 above, from the above, the count value of the zero cross counter 1 that was set to the zero cross value in step S114 is the predetermined time counted by the timer counter 1 in the immediate vicinity. This means the number of zero cross points generated during Ts. Therefore, the value obtained by dividing the predetermined time Ts by the zero cross value is the actual average time interval of the zero cross point at that time, in other words, the rotational state of the brushless motor 51, that is, the rotational speed. It is. The switching timing of the drive pulse signal should be changed according to the rotational speed. The timing is based on the rotational speed as the elapsed time (energization delay time) from the zero cross point as a reference. Thus, it is calculated by a predetermined arithmetic expression. Therefore, the energization delay time can be obtained based on the zero cross value at the predetermined time Ts.

After the process of step S114 is executed as described above, the count value of the zero cross counter 1 is cleared, that is, zero (see step S116 in FIG. 3), and the process proceeds to step S118.
In step S118, the energization delay time td is calculated from a predetermined arithmetic expression based on the zero cross value obtained in the previous step S114. The calculated energization delay time td is used for execution of a program for controlling the output of a drive pulse signal (not shown), and when the energization delay time has elapsed from the zero cross point, the corresponding stator windings 52a to 52d. A drive pulse signal is applied to 52c via the drive circuit 102.

Here, the energization delay time td is a time until the drive pulse signal is applied to the stator windings 52a to 52c with reference to the zero cross point.
That is, as shown in FIG. 8, the control unit 101 determines the zero cross point (see FIG. 8A) based on the signal from the position detection circuit 103 and outputs the output signal ( The position of the rotor (not shown) is recognized according to the mutual output levels of FIGS. 7C to 7E (see FIG. 8B), and on the basis of which, any of the stator windings is next detected. Whether to apply a drive pulse signal to 52a to 52c is determined.

FIG. 8B shows the rotor positions recognized at the zero cross point as described above for convenience in six of “position 1” to “position 6”. In the embodiment of the present invention, the change of the output signals of the comparators 41a to 41c is a repetition of six patterns as shown in FIGS. 7C to 7E. It corresponds to that.
That is, the output signals of the comparators 41a to 41c are: (1) When the V phase is at a level corresponding to the logic value Low and the W phase is at a level corresponding to the logic value High, the U phase changes from the logic value Low to High → (2) When the U phase is at a level corresponding to the logical value High and the V phase is at a level corresponding to the logical value Low, the drive pulse signal to the W phase changes from the logical value High to Low → (3) the U phase is the logical value High, W phase Is at a level corresponding to the logic value Low, the drive pulse signal to the V phase changes from the logic value Low to High → (4) the V phase is at a level corresponding to the logic value High and the W phase is at a level corresponding to the logic value Low. In some cases, the drive pulse signal for the U phase changes from the logic value High to Low → (5) When the U phase is at a level corresponding to the logic value Low and the V phase is at a level corresponding to the logic value High, the drive to the W phase Pulse signal from logic low Change to high → (6) When the U phase is at a level corresponding to the logical value Low and the W phase is at a level corresponding to the logical value High, the V phase changes from the logical value High to Low. Thus, after the output signal is changed, the change from the previous (1) is repeated again (see FIGS. 7C to 7E). The change in the output signals of the comparators 41a to 41c repeats the six patterns in this manner. The change in the drive pulse signal for the brushless motor 51 in the embodiment of the present invention repeats the six patterns as described above. It is because it is a thing.

Then, according to the generation order of the drive pulse signals for the stator windings 52a to 52c determined based on the rotor position recognized by the control unit 101 as described above, the latest delay time td, that is, The drive pulse signal is applied at the time (see FIG. 8C) after the delay time td calculated in step S118 described above or in any of steps S128, S138, S150, or S160 described later. The steps are sequentially performed (see FIG. 8D). 8C shows the application timing of the drive pulse signal, and FIG. 8D shows the excitation order of the stator windings 52a to 52c by the drive pulse signal, in other words, the drive pulse described above. The six patterns of signal change are shown in order.
The energization delay time td is, for example, 30 degrees in electrical angle when the brushless motor 51 is at 1000 rpm.

After the energization delay time td is obtained as described above, the timer counter 1 is cleared (see step S120 in FIG. 3), and the passage of the predetermined time Ts from zero is counted again.
Next, it is determined whether or not the count value of the timer counter 2 has reached the predetermined time Ts (see step S122 in FIG. 3), and when it is determined that the count value has not yet reached the predetermined time Ts (in the case of NO) ), The process proceeds to step S132 described later. On the other hand, if it is determined that the count value has reached the predetermined time Ts (in the case of YES), the count value of the zero cross counter 2 at this time is a variable. A certain zero cross value is set (see step S124 in FIG. 3). Then, the count value of the zero cross counter 3 is cleared (see step S126 in FIG. 3), and the process proceeds to step S128.

In step S128, the energization delay time td is calculated from a predetermined arithmetic expression based on the zero cross value obtained in the previous step S124, and used for output control of the drive pulse signal as described above. Become.
Next, the timer counter 2 is cleared (see step S130 in FIG. 3), and the elapsed time Ts from zero is counted again.

Hereinafter, similarly to the calculation of the energization delay time using the timer counter 1 and the zero cross counter 1, the calculation of the energization delay time using the timer counter 3 and the zero cross counter 3 (steps S132 to S136 in FIG. 3 and FIG. 4 (see steps S138 and S140), calculation of energization delay time using the timer counter 4 and zero cross counter 4 (see steps S142 to S150 in FIG. 4), energization delay time using the timer counter 5 and zero cross counter 5 Is calculated (see steps S152 to S160 in FIG. 4). In addition, after the process of step S160, it returns to the process of step S110 (refer FIG. 3), and a series of processes will be repeated.
Here, the content of each step after step S122 is basically the same as steps S112 to S120 described above except that the target timer counter and the zero cross counter are different, and here, Detailed description of the above will be omitted.

  As described above, according to the drive control process in the embodiment of the present invention, the energization delay time td is updated every predetermined time α which is a deviation of the counting start time of the timer counters 1 to 5. The energization delay time td calculated in each is calculated based on the zero cross value that is the number of zero cross points detected during the predetermined counting time Ts of the timer counters 1 to 5. The zero cross value is updated every time the zero cross point is detected at a time corresponding to the shift time α of the counting start times of the timer counters 1 to 5. In other words, since the zero cross value, which is the number of detected zero cross points within the predetermined time Ts, is updated by the time α (α <Ts) and the energization delay time td is obtained, the rotation of the brushless motor 51 Unlike the case where the calculation and calculation of the energization delay time is performed in almost real time while calculating the energization delay time td according to the state while maintaining an appropriate real-time property, there is no processing burden on the control unit 101. It can be executed with an appropriate margin.

For example, when a three-phase brushless motor is controlled to rotate at 1000 rpm, a zero crossing point occurs every 60 degrees of electrical angle, but each time it rotates during the period corresponding to the electrical angle of 60 degrees immediately before it. In the conventional drive control that calculates the switching timing of the driving pulse signal based on the speed, the switching timing of the driving pulse signal is calculated every 0.083 revolutions, and the value is updated. Although this drive control method has very good real-time performance in the calculation results, the load on the calculation processing of the control device, specifically, the microcomputer, is extremely large.
Further, in the case of the conventional drive control in which the switching timing of the drive pulse signal is calculated and updated every time the zero cross point is detected four times in the same rotation state as described above, based on the rotation speed during that time. The drive pulse signal switching timing is calculated once per rotation. In the case of this drive control, the real-time property in the calculation result is low as compared with the above-described conventional drive control, but the burden on the microcomputer is light and less expensive than when using the above-described conventional drive control. A microcomputer is enough.
On the other hand, in the case of the above-described embodiment of the present invention, the switching timing of the drive pulse signal is calculated and updated every 0.4 rotation, compared with the above-described conventional drive control, Although the real-time performance in the calculation results is slightly inferior, the real-time performance is sufficiently practical compared to the latter case of conventional drive control, and, unlike the former case, is a heavy burden on the microcomputer. This can be realized by using a microcomputer that is relatively inexpensive as compared with the case of realizing the former drive control.

  In the embodiment of the invention described above, the zero cross detection means is realized by the determination of the zero cross point of the output signal of the position detection circuit 103 performed by the control unit 101. In addition, the timing means is controlled by executing steps S100 to S108, S112, S120, S122, S130, S132 (see FIG. 3), S140, S142, S150, S152, and S160 (see FIG. 4) in the control unit 101. The zero cross counting means is executed by the execution of steps S200 to S208 (see FIG. 5) in the unit 101, and the timing is further determined by the execution of S118, S128 (see FIG. 3), S138, S148, and S158 (see FIG. 4) by the control unit 101. Each calculation means is realized.

  In the above-described embodiment, five timer counters are used. However, of course, the present invention is not limited to this, and more timers are required to improve the real-time property of the calculated value of the energization delay time. It is sufficient to use a counter and a zero crossing counter and set the shift of the counting start time to a smaller time. Naturally, the load on the control unit 101 increases as the real-time performance is improved. Become.

  In the above embodiment, the energization delay time of the drive pulse signal applied to the sensorless / brushless motor is calculated using a plurality of timer counters and zero cross counters. Even in a brushless motor having a dedicated sensor (for example, a magnetic sensor) for detection, the detection signal of the sensor may be used instead of the output signal of the position detection circuit 103 in the embodiment of the present invention. The energization delay time can be obtained in the same manner as described in the embodiment of the present invention.

It is a block diagram which shows one structural example of the drive control apparatus of the brushless motor in embodiment of this invention. FIG. 2 is a circuit diagram showing a circuit configuration example of a position detection circuit used in the brushless motor drive control device shown in FIG. 1. It is a flowchart which shows the procedure of the drive control process performed in the drive control apparatus of the brushless motor shown by FIG. FIG. 4 is a flowchart showing a procedure in the continuation of the drive control process shown in FIG. 3. FIG. FIG. 3 is a flowchart showing a procedure of zero cross counter processing that is interrupted in the brushless motor drive control device shown in FIG. 1. FIG. It is explanatory drawing explaining the count timing of the timer counters 1-5. FIG. 7A is a schematic waveform diagram for explaining the relationship between the zero cross point detected by the position detection circuit and the timing of the zero cross counter interrupt processing, and FIG. 7A shows an example of the induced voltage in the stator winding. FIG. 7B is a schematic waveform diagram showing a schematic output waveform of the filter circuit, and FIG. 7C is a schematic output waveform of the comparator to which the U-phase induced voltage is applied via the filter circuit. FIG. 7D is a schematic waveform diagram showing a schematic output waveform of the comparator to which the V-phase induced voltage is applied via the filter circuit, and FIG. 7E is a schematic waveform diagram showing the W waveform via the filter circuit. FIG. 7F is a schematic waveform diagram showing a schematic output waveform of the comparator to which the phase induced voltage is applied, and FIG. 7F is a timing diagram of the interrupt timing at the start of the zero cross counter processing. FIG. 8A is a schematic diagram for explaining the application timing of the drive pulse signal, FIG. 8A is a schematic diagram schematically showing the timing of the zero cross point, and FIG. 8B is a diagram showing the detected rotor position. FIG. 8C is a schematic diagram schematically illustrating the application timing of the drive pulse signal, and FIG. 8D is a schematic diagram schematically illustrating the excitation order of the stator windings. is there.

Explanation of symbols

51 ... Brushless motors 52a to 52c ... Stator winding 101 ... Control unit 102 ... Drive circuit 103 ... Position detection circuit

Claims (3)

The duty of a drive pulse signal applied to the stator winding of the brushless motor is set based on the rotational position signal of the rotor of the brushless motor and the desired rotational speed, and the stator winding is set based on the rotational position signal of the rotor. A drive control method for a brushless motor configured to control the switching timing of the drive pulse signal to
While the counting of the second predetermined time is repeatedly performed by a plurality of timer counters whose counting start time is shifted every first predetermined time,
Detecting the zero cross point where the rotational position signal of the rotor exceeds a reference level, and repeatedly counting the number of times of detection of the zero cross point within the second predetermined time by the respective timer counters,
Each time the second predetermined time is counted by the plurality of timer counters, the switching timing of the drive pulse signal is determined based on the number of detections of the zero cross point within the second predetermined time. A drive control method for a brushless motor. The duty of a drive pulse signal applied to the stator winding of the brushless motor is set based on the rotational position signal of the rotor of the brushless motor and the desired rotational speed, and the stator winding is set based on the rotational position signal of the rotor. A brushless motor drive control program executed in a brushless motor drive control device configured to control the switching timing of the drive pulse signal to:
Detecting a zero-crossing point where the rotational position signal of the rotor inputted externally exceeds a reference level;
Counting each time a zero cross point is detected in the step;
A step of repeatedly counting the second predetermined time by a plurality of timer counters shifted in counting start time by the first predetermined time;
Every time the counting of the second predetermined time of the plurality of timer counters is completed, the switching timing of the drive pulse signal is calculated based on the count value of the zero cross point within the second predetermined time. Steps,
A drive control program for a brushless motor, comprising: The duty of a drive pulse signal applied to the stator winding of the brushless motor is set based on the rotational position signal of the rotor of the brushless motor and the desired rotational speed, and the stator winding is set based on the rotational position signal of the rotor. A drive control device for a brushless motor configured to control the switching timing of the drive pulse signal to
A zero cross detecting means for detecting a zero cross point at which the rotational position signal of the rotor inputted externally exceeds a reference level;
Time counting means for repeatedly counting the second predetermined time by a plurality of timer counters whose counting start time is deviated every first predetermined time;
Zero cross counting means for counting the number of zero cross points detected by the zero cross detecting means within the second predetermined time by each timer counter in the time measuring means;
The driving pulse is calculated based on the count value of the zero cross point by the zero cross counting means within the second predetermined time every time the timer counter in the time counting means completes counting for the second predetermined time. Timing calculation means for calculating and calculating signal switching timing;
A drive control device for a brushless motor, comprising:

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