JPH08223974A - Control method for brushless motor - Google Patents

Abstract

PURPOSE: To stabilize the rotation of a brushless motor while reducing vibration and noise by switching the conduction of an armature winding appropriately using an inexpensive microcomputer as a control circuit for the brushless motor. CONSTITUTION: A comparison circuit 10b compares the terminal voltage (induced voltage) of the armature winding of a brushless motor 3 with a reference voltage and a control circuit 11 detects a position signal D varying at an intersection. Time T of a single period (electric angle of 360 deg.) after variation and the times corresponding to electric angles of 30 deg., 90 deg. and 150 deg. are then calculated. The time corresponding to an electric angle of 30 deg. is determined before the current variation point of the position signal D whereas the times corresponding to electric angles of 90 deg. and 150 deg. are determined after the current variation point of the position signal D. The time thus determined is then measured and conduction of the armature winding of the brushless motor 3 is switched upon expiration of the determined time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation control technique for a DC brushless motor (hereinafter referred to as a brushless motor) used in a compressor of an air conditioner, and more particularly, to optimally switch a winding current of the brushless motor, The present invention relates to a brushless motor control method for stabilizing rotation control of a brushless motor.

[0002]

2. Description of the Related Art In the rotation control of a brushless motor, a Hall element is not used as a means for detecting the position of a rotor (rotor), but a voltage induced in an armature winding of the brushless motor is used. There is.

In order to control the rotation of the brushless motor by detecting the position of the rotor using the above-mentioned induced voltage and switching the energization of the brushless motor based on the detected position, for example, in the case of a three-phase motor It requires the control device shown in FIG.

In FIG. 10, this control device includes a voltage doubler rectifying and smoothing circuit 2 for voltage doubler rectifying and smoothing an AC power supply (commercial 100V), and a DC voltage Vdc that has been voltage doubled rectified and smoothed. An inverter circuit 4 in which a plurality of switching elements (transistors) U, V, W, X, Y, and Z are bridge-connected for switching and applying to the armature winding of the brushless motor 3, and a terminal voltage of the brushless motor 3 ( For example, the position detector 5 that detects the position of the rotor 3a based on R, S, and T, which are voltages having a phase difference of 120 degrees (including induced voltages), and the energization of each armature winding of the brushless motor 3 are predetermined. And a control circuit that outputs a drive signal for the inverter circuit 4 in order to switch the energization of each armature winding based on the position detection signals A, B, and C from the position detection unit 5 in a predetermined manner. 6, the switching elements of the inverter circuit 4 by the drive signal (transistor) U, V,
A drive circuit 7 for turning on / off W, X, Y, and Z is provided.

When the above control device is used to control the compressor of the air conditioner, a power factor improving reactor 8 is provided between the AC power supply 1 and the voltage doubler rectifying and smoothing circuit 2.

The position detecting unit 5 is combining a differentiating circuit 5b and an integrating circuit 5c for delaying and smoothing the voltage waveforms of the terminal voltages R, S and T by 90 degrees, and these 90-degree phase delayed voltages. The resistance circuit 5c for obtaining the neutral point potential Vn, the 90 ° phase delayed voltage and the neutral point potential Vn
And a comparison circuit 5d for comparing position and outputting position detection signals A, B and C.

The control circuit 6 is composed of a microcomputer, a drive circuit and the like, and outputs a drive signal to drive the transistors U, V, W, X, Y and Z of the inverter circuit 4.

In the control device having the above-mentioned structure, when the brushless motor 3 is started, for example, the brushless motor 3 is synchronously operated for a predetermined time, but after the predetermined time has elapsed, the brushless motor 3 is operated based on the position detection signals A, B and C. Rotation control (switch to operation by so-called position detection).

In the operation by the position detection, the position of the rotor 3a is detected, and the energization of each armature winding is switched based on the position detection.
For example, the terminal voltages R, S, and T of the armature windings shown in FIGS. 11A to 11C are phase-delayed by 90 degrees, and the phase-delayed voltage (shown in FIGS. 11D to 11F). Is compared with the neutral point potential Vn, and position detection signals (shown in FIGS. 11 (g) to 11 (i)) A, B and C that change at the intersections are output.

The position detection signals A, B and C are controlled by the control circuit 6.
When input to the position detection signal A, B,
Based on the timing of C, a drive signal (shown in FIGS. 11 (j) to 11 (o)) for switching the conduction states of the transistors U, V, W, X, Y, and Z of the inverter circuit 4 is generated.

Each transistor U, V,
Since W, X, Y and Z are driven, the brushless motor 3
The armature winding current of the brushless motor 3
Is controlled to rotate.

The control circuit 6 outputs a chopping signal to the drive circuit 7 in addition to the drive signal.
Chops the ON portion of the drive signal of the transistor of the upper arm (or lower arm) of the inverter circuit 4 at a predetermined duty ratio (ON / OFF ratio) (shown in FIGS. 11 (j) to 11 (l)).

As described above, the armature winding currents of the brushless motor 3 are switched based on the position detection signals A, B and C to control the rotation of the brushless motor 3 and the on / off ratio of chopping is changed. The brushless motor 3 is controlled to a predetermined rotation speed.

[0014]

In the brushless motor control method, the position of the rotor 3a is detected using the integrating circuit 5b, and the armature winding winding is detected based on this position detection. Since the timing to switch the power supply is obtained,
The following problems occur.

As one of them, various frequency components are mixed in the voltage waveform induced in the armature winding, and constants cannot be determined for all the frequencies due to the characteristics of the integrating circuit (integrating filter) 5b. . Therefore, the voltage waveform passing through the integrating circuit includes an unnecessary frequency component, and in particular, the frequency included due to the change in the rotation speed of the brushless motor 3 causes an error in the output delay of 90 degrees, resulting in the position of the rotor 3a. There is an error in detection.

Further, since the integration circuit 5b is required, not only the cost is inevitably increased, but also the control board is large due to the increase in the number of parts, and the space is taken up.

Further, although the 90 ° delay obtained through the integrating circuit 5b is always constant, the 90 ° delay is not optimum depending on the rotation speed and load condition of the brushless motor 3, that is, the energization that maximizes the efficiency of the brushless motor 3. Since the switching timing varies depending on the number of revolutions and load condition,
It is not possible to switch the energization for maximum efficiency at all times.

Therefore, there is a method of controlling the brushless motor 3 by detecting the position of the rotor 3a without using the integrating circuit 5b. In the case of this control method, the voltage waveform induced in the armature winding is compared with the neutral point potential, and the comparison result is the control circuit of the brushless motor 3 (microcomputer).
Is input to and is calculated by this control circuit to determine the energization switching timing.

In this control method, unlike the method already described, the position detection signal is obtained directly based on the terminal voltage waveform (induced voltage waveform) of the armature winding without using the integrating circuit 5b. Therefore, for example, the energization can be switched from the position detection point at a time of 30 degrees which is the first energization switching timing.

However, since the time of 30 degrees is extremely short, when the time of 30 degrees is calculated on the basis of the position detection signal, this calculation will not be completed by the actual energization switching time. Therefore, a microcomputer with a high-speed calculation function will be used,
Inevitably an expensive microcomputer must be used, resulting in an increase in cost.

The present invention has been made in view of the above problems, and an object thereof is to be able to optimally switch energization of a brushless motor without using an integrating circuit, and to realize it with an inexpensive microcomputer. Another object of the present invention is to provide a brushless motor control method.

[0022]

In order to achieve the above object, the present invention applies a DC power source to a brushless motor having a multi-phase armature winding by switching the DC power source with inverter means, and rotates the brushless motor. A method for controlling a brushless motor that drives the inverter means based on position detection of an armature to switch energization of the armature winding by comparing an induced voltage generated in the armature winding with a reference voltage. A position signal synchronized with the rotation of the brushless motor is obtained, and one cycle time (a time corresponding to an electrical angle of 360 degrees) or half cycle time (an electrical angle of 180 degrees is obtained) based on the position detection point of the position signal. (Corresponding time) is measured, and the measured time is always stored for a predetermined number of times. Based on the time of one cycle or half cycle that was previously measured, The time corresponding to the calculated predetermined electrical angle is measured from the current position detection point, and at the end of the time measurement, the armature winding The point is to switch the energization.

Further, in the brushless motor control method of the present invention, the induced voltage generated in the armature winding is compared with the reference voltage to obtain a position signal synchronized with the rotation of the brushless motor, and the position signal Based on the change point, one cycle time (time corresponding to an electrical angle of 360 degrees) or half cycle time (time corresponding to an electrical angle of 180 degrees) is measured, and the measured time is always a predetermined number. While storing and calculating the time corresponding to at least the smallest predetermined electrical angle (the earliest energization switching timing) based on the time of one cycle or half cycle that was previously measured, before the change point of the current position signal , A time corresponding to the calculated predetermined electrical angle is measured from the current position detection point, and at the end of the time measurement, the energization of the armature winding is set to be switched, and the current calculated 1 The predetermined electrical angle is measured based on the time of the period, and the calculation of the time corresponding to the predetermined electrical angle at the end of each electrical angle is larger than the predetermined time, and when the energization switching timing is reached in time, after the current position detection point. The energization is switched using the calculated time.

Further, in the brushless motor control method of the present invention, the brushless motor is a three-phase motor, and the induced voltage and the reference voltage generated in one armature winding of the brushless motor. And the time corresponding to the predetermined electrical angle of 30 degrees, 90 degrees, and 150 degrees is calculated from the intersection (position detection point) of the comparison result, and the energization is switched by measuring the calculated time. It is the one.

[0025]

According to the above means, the terminal voltage (induced voltage) of the armature winding of the brushless motor is compared with the reference voltage,
A position signal synchronized with the rotation of the rotor, which changes at the intersection, is obtained according to the comparison result.

One cycle time (time corresponding to an electrical angle of 360 degrees) is measured by the position detection point, and at least one cycle time measured last time and this time is stored. The time (electrical phase angle of 30 degrees, 90 degrees, and 150 degrees) corresponding to the timing at which the energization of the armature winding is switched from the position detection point is calculated based on the measured time.

The time corresponding to an electrical angle of 30 degrees was calculated before the current position detection based on the time of one cycle previously measured, and the times corresponding to an electrical angle of 90 degrees and 150 degrees were measured this time. It is calculated after the current position detection based on the time of one cycle.

In this way, from the position detection this time, the electrical angle 3
Even if the time until the energization switching at the point delayed by 0 degree is short, the time corresponding to the electrical angle of 30 degrees is calculated before the current position detection. Therefore, as the microcomputer, which is the control circuit for controlling the rotation of the brushless motor, a microcomputer with a slow operation speed, that is, an inexpensive one can be used.

Further, the time corresponding to the electrical angle of 30 degrees is calculated based on the time of one cycle measured this time, and this calculation is in time from the current position detection to the energization switching of the electrical angle 30 degree delay point. Sometimes calculated electrical angle 30
The energization is switched when the time corresponding to

For example, when the brushless motor has a low rotation speed, even if the microcomputer is a low speed,
This is because it is possible to calculate the time corresponding to the electrical angle of 30 degrees based on the time of one cycle measured this time before switching the energization of the electrical angle 30 degree delay point.

As described above, since the time corresponding to each electrical angle of 30 degrees, 90 degrees and 150 degrees is calculated based on the time of one cycle counted this time, the energization switching of the brushless motor is optimal. As a result, uneven rotation, vibration and noise are further suppressed.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A brushless motor control method according to the present invention is
For example, the position detection point at the intersection of the one-phase terminal voltage (induced voltage) of the three-phase DC brushless motor (hereinafter referred to as a brushless motor) and the reference voltage is detected, and one cycle time ( Based on a time corresponding to an electrical angle of 360 degrees, a predetermined phase angle (electrical angle of 30 degrees, 90 degrees, 150 degrees)
Degree) When calculating the time corresponding to the delay point, if the calculation of the time corresponding to the electrical angle of 30 degrees is started before the current position detection, even if the calculation speed of the rotation control is slow, from the current position detection point. Paying attention to the fact that the energization switching timing of the electrical angle of 30 degrees is reached, the electrical angle of 30 degrees starts before the position detection point.

Even after the current position detection, the electrical angle 30
The time corresponding to the electric angle is calculated, and when the calculation is in time from the current position detection to the energization switching timing of the electrical angle of 30 degrees, the energization is switched at the time corresponding to the currently calculated electrical angle of 30 degrees.

Therefore, the controller to which the brushless motor control method of the present invention is applied has, for example, the configuration shown in FIG. Note that, in the figure, the same parts as those in FIG.

In FIG. 1, this control device is arranged so that one of the terminal voltages (including the induced voltage) R, S, T of the three armature windings of the three-phase four-pole brushless motor 3, for example, the terminal voltage R The position detection unit 10 that outputs the position signal D by comparing with the reference voltage Vdc / 2 and the position detection point (rising edge or falling edge) of this position signal D make one cycle time (equivalent to an electrical angle of 360 degrees). Time) for each of the same position detection points, at least one cycle time of this time and the previous time is stored, and a predetermined phase angle (for example, an electrical angle of 30 is calculated based on the stored one cycle time). Degree 9
0 degrees and 150 degrees), and at least the time corresponding to an electrical angle of 30 degrees is calculated based on the time of one cycle previously measured before the current position detection. A control circuit (microcomputer) 11 is provided to switch the energization of the armature windings of the brushless motor 3 at the points where the calculated times have elapsed from the position detection points.

The position detecting section 10 has a predetermined reference voltage Vdc.
A reference voltage generation circuit 10a for generating / 2 and a comparison circuit 10b for comparing the generated reference voltage with the induced voltage waveform are provided. The control circuit 11 turns on and off the transistors U, V, W of the upper arm or the transistors X, Y, Z of the lower arm of the inverter circuit 4 during PWM control, and a chopping signal for chopping the on part of the driving signal. It also has a function of outputting a control signal for switching this chopping to the upper arm or the lower arm.

Further, the control device receives the drive signal, the chopping signal and the control signal from the control circuit 11, chops the ON part of the drive signal, and drives the inverter circuit 4 by the drive signal including the chopped drive signal. Is provided with a drive circuit 12 for driving the respective transistors U, V, W, X, Y, Z.

Next, the operation of the control device will be described in detail with reference to the time chart of FIG. 2 and the flow charts of FIGS. 3 to 6. First, since the induced voltage is not generated when the brushless motor 3 is started, Control circuit 1
1 executes the already known synchronous operation.

By this synchronous operation, the brushless motor 3 is gradually accelerated from a low frequency, and the position signal D output from the position detecting section 10 makes it possible to detect the intersection of the induced voltage and the reference voltage, that is, an appropriate position. The above processing is executed until the signal D is obtained.

Then, the R-phase terminal voltage R of the brushless motor 3 is normally input to the position detector 10 (FIG. 2 (b)).
The position detection unit 10 compares the induced voltage of the terminal voltage R with the reference voltage Vdc / 2 from the reference voltage generation circuit 3a in the comparison circuit 10b, and outputs the position signal D of the comparison result (see FIG. c)).

Here, the control circuit 11 detects the change point (rising edge or falling edge) of the input position signal D. For example, when the induced voltage is rising, the upper arm transistors U, V, W of the inverter circuit 4 are PWM-controlled, and the first rising edge of the position signal D after the energization switching timing (t1, t shown in FIG. 2).
3) is detected. When the induced voltage is falling, the lower arm transistors X, Y, Z of the inverter circuit 4 are set to P
WM control is performed, and the first falling edge (t2, t7 shown in FIG. 2) after the energization switching timing is detected.

In the PWM control, the control circuit 11
The drive signal, the chopping signal, and the control signal from the drive circuit 12 are input to the drive circuit 12, and the drive circuit 12 synthesizes the predetermined drive signal and the chopping signal according to the control signal, and the drive signal including the synthesized drive signal is used. The inverter circuit 4 is driven.

Each time the edge of the input position signal D is detected, the routine shown in FIGS. 3 to 6 is executed. First, assuming that the edge is detected at time t3, the current time ta of this detection is set by the free running timer. Detected and this time t
a is temporarily stored in the internal memory (step ST1).

Subsequently, at this time ta, a time T (30) = T2 × (30/36) corresponding to the previously calculated electrical angle of 30 degrees.
0) is added (step ST2), and this time ta + T
(30) = t (30) is set in the compare register A of the free running timer of the control circuit 11 (step ST3).

The time T (3
The calculation of 0) = T2 × (30/360) will be described later, but before the edge of the position signal D (time t3), the calculation for calculating the time T (30) is started. Therefore, the time t (30) =
It is possible to calculate ta + T (30), and this time t
(30) can be set in the compare register A.

Subsequently, it is determined whether the detection edge of the position signal D is rising or falling (step ST
4) If it is a rising edge, step ST5
Then, a preset flag is set in the control circuit 11 (set to "1"), and if it is a falling edge, the process proceeds to step ST6 to clear the flag (set to "0").

After that, when the value of the compare register A matches the value of the free running timer, t shown in FIG.
(30) When the interrupt routine is executed and the above flag is set, steps ST20 to ST21
Then, the signal driving the transistor W of the inverter circuit 4 is turned off (shown in FIG. 2 (f)), and the signal driving the transistor U is turned on (shown in FIG. 2 (d)). At the same time, the control signal for switching from the upper arm to the lower arm chopping is controlled so as to chop the signals for driving the transistors X, Y, Z forming the lower arm of the inverter circuit 4.
(Step ST22).

On the other hand, when the flag is cleared, the process proceeds from step ST20 to ST23, the signal for driving the transistor Z of the inverter circuit 4 is turned off (as shown in FIG. 2 (i)), and the transistor X is driven. The signal to be turned on is turned on (shown in FIG. 2 (g)). At the same time, a control signal for switching from the lower arm to the upper arm chopping is output to the drive circuit 12 so as to chop the signals for driving the transistors U, V, W forming the upper arm of the inverter circuit 4. Yes (step ST24).

When the interrupt process is completed, the process returns to the main routine. In the main routine, the time T (90) corresponding to the electrical angle of 90 degrees is calculated.
Between the time and the time, one cycle time (time corresponding to an electrical angle of 360 degrees) T3 is calculated (step ST7). in this case,
The time t3 at time t1 is calculated by subtracting the time tc at time t1 from the time ta at time t3.

Subsequently, the calculated time T3 is used to calculate a time T (90) = T3 × (90/360) corresponding to a phase angle of 90 degrees from the detected edge of the position signal D, and the calculated time T is calculated. (90) is added to time ta to calculate the time at which the electrical angle is 90 degrees (step ST8), and this calculated time t (90) = ta + T (90) is set in the compare register B (step ST9).

After that, when the value of the compare register B matches the value of the free running timer (t5 shown in FIG. 2).
Time point), the t (90) interrupt routine shown in FIG. 5 is executed. When the flag is set, the process proceeds from step ST30 to ST31 to turn off the signal for driving the transistor Y of the inverter circuit 4 (shown in FIG. 2 (h)) and turn on the signal for driving the transistor Z. (Shown in FIG. 2 (i)). At the same time, the transistors U, V, which form the upper arm of the inverter circuit 4,
A control signal for switching from the lower arm to the upper arm chopping is output to the drive circuit 12 so as to chop the signal for driving W (step ST3).
2).

On the other hand, when the flag is cleared, the process proceeds from step ST30 to ST33, the signal for driving the transistor V of the inverter circuit 4 is turned off (as shown in FIG. 2 (e)), and the transistor W is driven. The signal to be turned on is turned on (shown in FIG. 2 (f)). At the same time, a control signal for switching from the upper arm to the lower arm is output to the drive circuit 12 so as to chop the signals for driving the transistors X, Y, Z forming the lower arm of the inverter circuit 4. (Step ST34).

When the interrupt process is completed, the process returns to the main routine. In the main routine, since the time T (150) corresponding to the electrical angle of 150 degrees is calculated, the time T (corresponding to the electrical angle of 150 degrees from the edge of the position signal D is calculated using the time T3 of one cycle which has already been stored. 150) = T3
* (150/360) is calculated, and this calculated time T (150) is added to the time ta to obtain the electrical angle 150
Time t (150) of degree (step ST10),
The calculated time t (150) = ta + T (150) is set in the compare register C (step ST11).

Thereafter, when the value of the compare register C and the value of the free running timer match (t6 shown in FIG. 2).
At the time point), the t (150) interrupt routine shown in FIG. 6 is executed. When the flag is set, the process proceeds from step ST40 to ST41 to turn off the signal for driving the transistor U of the inverter circuit 4 (shown in FIG. 2D) and turn on the signal for driving the transistor V. (Shown in FIG. 2 (e)). At the same time, the transistor X, which constitutes the lower arm of the inverter circuit 4,
A control signal for switching from the upper arm to the lower arm chopping is output to the drive circuit 12 so as to chop the signals for driving Y and Z (step S).
T42).

On the other hand, when the flag is cleared, the process proceeds from step ST40 to ST43, the signal for driving the transistor X of the inverter circuit 4 is turned off (as shown in FIG. 2 (g)), and the transistor Y is driven. The signal to be turned on is turned on (shown in FIG. 2 (h)). At the same time, a control signal for switching from the lower arm to the upper arm chopping is output to the drive circuit 12 so that the signals for driving the transistors U, V, W forming the upper arm of the inverter circuit 4 are chopped. Yes (step ST44).

When the interrupt process is completed, the process returns to the main routine. In the main routine, the time T3 of one cycle corresponding to the electrical angle of 360 degrees is used to calculate the time T (30) = T3 × (30/360) corresponding to the electrical angle of 30 degrees, which is stored in the memory (step ST12). ). This time T
The calculation of (30) is to be used in step ST2 when the main routine is repeated.

Subsequently, a time tb (see FIG. 2) at which the edge of the previously detected position signal D is detected is stored in a memory storing a time tc at which the edge of the position signal D is detected two times before (time t1 shown in FIG. 2). At time t2 shown in the drawing, the time tb of the previous time is stored by changing it to the time tc of the last two times (step ST13). Further, the edge time ta (t3 shown in FIG. 2) of the position signal D of this time detection is written to the memory that stores the time tb of the edge of the position signal D of the previous detection (time t2 shown in FIG. 2) (step ST14). ), That is, it is necessary to reserve one memory in order to obtain the time of the edge of the next position signal D.

When the edge of the input position signal D is detected, the main routine is executed again, and the current time ta of the edge detection (time t7 shown in FIG. 2) is stored in the memory (step ST1). The time T (3
0) = T3 × (30/360) is added to the current time ta (step ST2), and this time ta + T (30) = t
(30) is set in the compare register A (step ST3). Next, the flag is processed (steps ST4 to ST6). After that, when the value of the compare register A and the value of the free running timer match, the interrupt processing shown in FIG. 4 is executed.

When the interrupt process is completed, the process returns to the main routine. In the main routine, the time T (90) corresponding to the electrical angle of 90 degrees is calculated.
Between the time point and time, one cycle time (time corresponding to an electrical angle of 360 degrees) T4 is calculated (step ST7). in this case,
The time T4 is calculated by subtracting the time t2 from the time t4 and stored.

Thereafter, in the same manner as described above, the main routine of FIG. 3 is executed, and when the values of the compare registers A, B, C and the free running timer match, the interrupt routine of FIGS. 4 to 6 is executed, and repeat.

More specifically, referring to the time chart of FIG. 2, since the edge of the position signal D is the falling edge at time t7, the flag is cleared (step ST
6) After that, when the time t (30) set in the compare register A has passed (time t8 shown in FIG. 2), the t (30) interrupt routine shown in FIG. 4 is executed.

In this case, since the flag is not set, the signal for driving the transistor Z of the inverter circuit 4 is turned off as described above (shown in FIG. 2 (i)).
The signal that drives the transistor X is turned on (Fig. 2
(Shown in (g)). At the same time, a control signal for switching from the lower arm to the upper arm chopping is output to the drive circuit 12 so that the signals for driving the transistors U, V, W forming the upper arm of the inverter circuit 4 are chopped. To do.

Further, the phase angle 90 from the edge of the position signal D
Time t (90) = t7 + T4 × (90/360) is calculated, and the (90) interrupt routine shown in FIG. 5 is executed at the time when this time t (90) has passed (time t9 shown in FIG. 2). .

In this case, since the flag is not set, the signal for driving the transistor V of the inverter circuit 4 is turned off and the signal for driving the transistor W is turned on as described above. At the same time, a control signal for switching from the upper arm to the lower arm is output to the drive circuit 12 so as to chop the signals for driving the transistors X, Y, Z forming the lower arm of the inverter circuit 4. To do.

Further, the phase angle 1 from the edge of the position signal D
Time t of 50 degrees t (150) = T7 + T4 × (150/3
60) is calculated, and the interrupt routine shown in FIG. 6 is executed when the time t (150) has elapsed.

In this case, since the flag is not set, the signal for driving the transistor X of the inverter circuit 4 is turned off as described above (shown in FIG. 2 (g)).
The signal that drives the transistor Y is turned on (see FIG. 2).
(Shown in (h)). At the same time, a control signal for switching from the lower arm to the upper arm chopping is output to the drive circuit 12 so that the signals for driving the transistors U, V, W forming the upper arm of the inverter circuit 4 are chopped. To do.

Thus, the induced voltage and the reference voltage Vdc /
The intersection with 2 is detected, and the time of one cycle (the time corresponding to an electrical angle of 360 degrees) is calculated and stored based on this intersection,
The time corresponding to a predetermined phase angle (electrical angle 30 °, 90 ° and 150 °) delay point from the intersection is calculated based on the time corresponding to electrical angle 360 °.

Further, the calculation of the time corresponding to the delay point of the electrical angle of 30 degrees is based on the one cycle time (the time corresponding to the electrical angle of 360 degrees) calculated and stored at the previous intersection point. It will be held before this intersection.

Therefore, the microcomputer as the control circuit 11 for controlling the rotation of the brushless motor 3 may have a slow operation speed, that is, the rotation control of the brushless motor 3 can be realized by an inexpensive microcomputer.

From the intersection, the electrical angle (30 degrees, 90 degrees
Since the energization of the brushless motor 3 is switched at the end of the lapse of the time corresponding to the delay point, the energization of the brushless motor 3 can be appropriately switched, and uneven rotation, vibration and noise can be suppressed. In addition, it is possible to prevent step-out and circuit damage, stabilize rotation control, and enable efficient operation.

7 to 9 are time charts and flow charts for explaining a modified embodiment of the present invention. For the brushless motor control device to which the control method of this modified example is applied, refer to FIG.

In this modified example, since the energization is switched at the delay point of the electrical angle of 30 degrees from the intersection point of the induced voltage waveform and the reference voltage Vdc / 2, the time corresponding to the electrical angle of 30 degrees is calculated. The calculation is started from (the change point of the position signal D of this time), and when this calculation is not in time for the energization switching of the electrical angle of 30 degrees, it corresponds to the electrical angle of 30 degrees calculated before the current position detection of the previous embodiment. Use time.

Therefore, the controller of this brushless motor has a control circuit (microcomputer) 20 shown in FIG.
It has. This control circuit 20 has the induced voltage waveform and the reference voltage V in addition to the function of the control circuit 11 shown in the previous embodiment.
When the intersection point with dc / 2 (the change point of the position signal D this time) is detected, the electrical angle 30 is calculated by the time of one cycle calculated based on this change point (the time corresponding to the electrical angle of 360 degrees).
While calculating the time corresponding to the degree, when the time calculation is not completed within the predetermined time, the energization switching timing is obtained based on the time corresponding to the electrical angle of 30 degrees calculated before the previous change point of the position signal D.

Next, a method of controlling the brushless motor applied to the control device having the above configuration will be described. Since FIG. 7 corresponds to FIG. 2 and FIGS. 8 and 9 correspond to FIG. 3, detailed description thereof will be omitted.

First, like the previous embodiment, the control circuit 20 executes the already known synchronous operation, the synchronous operation gradually accelerates the brushless motor 3 from a low frequency, and the position signal output from the position detecting section 10 is outputted. The above processing is executed until the intersection of the induced voltage and the reference voltage can be detected by D, that is, until the appropriate position signal D is obtained.

Then, the R-phase terminal voltage R of the brushless motor 3 is normally input to the position detector 10 (FIG. 7B).
The position detection unit 10 compares the induced voltage of the terminal voltage R with the reference voltage from the reference voltage generation circuit 3a in the comparison circuit 10a, and outputs the position signal D of this comparison result (FIG. 7).
(Shown in (c)).

Here, the control circuit 20 detects the changing point (rising edge or falling edge) of the input position signal D. For example, when the induced voltage is rising, the upper arm transistors U, V, W of the inverter circuit 4 are PWM-controlled, and the first rising edge of the position signal D after the energization switching timing (t1, t shown in FIG. 7).
3) is detected. When the induced voltage is falling, the lower arm transistors X, Y, Z of the inverter circuit 4 are set to P
WM control is performed, and the first falling edge (t2, t7 shown in FIG. 7) after the energization switching timing is detected.

Each time the edge of the input position signal D is detected, the routines shown in FIGS. 8, 9, 4, 5 and 6 are executed. First, assuming that the edge is detected at time t3,
The current time ta of this detection is detected by the free running timer, and this time ta is temporarily stored in the internal memory (step ST50).

Subsequently, the time T (30) = T2 × (3) corresponding to the electrical angle of 30 degrees already calculated at this time ta.
0/360) is added (step ST51), and this time ta + T (30) = t (30) is set in the compare register A of the free running timer of the control circuit 20 (step ST52). The calculation of the time T (30) = T2 × (30/360) corresponding to the electrical angle of 30 degrees will be described later.

Subsequently, a time period T3 (time period corresponding to an electrical angle of 360 degrees) T3 is calculated between the time points t1 and t3 (step ST53). In this case, the time t3 at the time point t1 is subtracted from the time ta at the time point t3 to calculate and store the time T3 for one cycle.

Using this calculated time T3, a time corresponding to an electrical angle of 30 degrees tt (30) = ta + T3 × (30/36)
0) is calculated (step ST54). Further, the current time ts is detected (step ST55), and the detected time ts is compared with the time tt (30) calculated in ST54 (step ST56).

When ts <tt (30), the process proceeds to step ST57, where the current time ts and step ST51 are set.
The time t (30) calculated in step s is compared, and ts <t (3
If it is 0), the process proceeds to step ST58 and t (3
Instead of 0), tt (30) is the time of the energization switching timing. That is, the contents of the compare register A are t
Change from (30) to tt (30).

That is, the current time ts has not reached the time already set in the compare register A, and at that time ts, the time tt (30) corresponding to the electrical angle of 30 degrees has already been calculated. Is.

Thus, based on the time T3 corresponding to the electrical angle of 360 degrees, the time T (3 corresponding to the electrical angle of 30 degrees is obtained.
0) = T3 × (30/360) is calculated to determine the energization switching time ta + T (30) = tt (30), and when this calculation process is in time until the energization switching of the electrical angle of 30 degrees, the time tt ( 30) is the energization switching timing.

On the other hand, the routine shown in FIG. 8 is executed by the detection edge of the position signal D, and it is determined whether the detection edge is rising or falling (step ST7).
0), if it is a rising edge, step ST7
In step 1, a preset flag is set in the control circuit 20 (set to "1"), and if it is a falling edge, the process proceeds to step ST72 to clear the flag (set to "0").

Subsequently, when the value of the compare register A matches the value of the free running timer, the interrupt routine shown in FIG. 4 is executed. See the previous example for this process.

When the interrupt process is completed, the process returns to the main routine. In the main routine, the calculated time T3
Is used to calculate the time T (90) = T3 × (90/360) corresponding to the phase angle of 90 degrees from the detected edge of the position signal D, and the calculated time T (90) is calculated at the time ta.
Is calculated to calculate the time at which the electrical angle is 90 degrees (step ST59), and the calculated time t (90) = ta + T (9
0) is set in the compare register B (step ST
60).

After that, when the value of the compare register B and the value of the free running timer match (t5 shown in FIG. 7).
Time point), the interrupt routine shown in FIG. 5 is executed. See the previous example for this process.

When the interrupt process is completed, the process returns to the main routine. In the main routine, since the time T (150) corresponding to the electrical angle of 150 degrees is calculated, the time T3 (150) corresponding to the electrical angle of 150 degrees from the edge of the position signal D is calculated by using the time T3 already stored. = T3 × (1
50/360) and the calculation time T
(150) is added to time ta to calculate time t (150) at the electrical angle of 150 degrees (step ST61), and this calculated time t (150) = ta + T (150) is set in the compare register C (step). ST62).

After that, when the value of the compare register C matches the value of the free running timer (t6 shown in FIG. 7).
At the time point), the interrupt routine shown in FIG. 6 is executed. See the previous example for this process.

When the interrupt process is completed, the process returns to the main routine. In the main routine, T (30) = tt
The time T (30) corresponding to the electrical angle of 30 degrees is calculated by (30) -t (30) and stored in the memory (step ST63). This time T (30) is calculated in step ST51 when the main routine is repeated.

Subsequently, a time tb (see FIG. 7) at which the edge of the previously detected position signal D is detected is stored in a memory storing a time tc at which the edge of the position signal D is detected two times before (time t1 shown in FIG. 7). At time t2 shown), that is, the time tc of the last two times is changed and the previous time tb is stored (step ST64). Further, the edge time ta of the position signal D of this time detection (t3 shown in FIG. 7) is written in the memory that stores the time tb of the edge of the position signal D of the previous detection (time t2 shown in FIG. 7) (step ST65). ), That is, it is necessary to reserve one memory in order to obtain the time of the edge of the next position signal D.

When the edge of the input position signal D is detected, the main routine shown in FIGS. 8 and 9 is executed again, and the current time ta of the edge detection (t7 in FIG. 7 is detected.
The time point) is stored in the memory (step ST1). The time T (30) corresponding to the electrical angle of 30 degrees calculated in step ST63 is added to the current time ta (step ST51), and this time ta + T (30) = t (30).
Is set in the compare register A (step ST5
2).

Thereafter, the same processing as described above is executed, and when the values of the compare registers A, B, C and the free running timer match, the interrupt routine of FIGS. 4 to 6 is executed and repeated.

More specifically, referring to the time chart of FIG. 7, since the edge of the position signal D is the falling edge at time t7, the flag is cleared (step ST
72) and thereafter, when the time t (30) set in the compare register A has elapsed (time t8 shown in FIG. 7), the interrupt routine shown in FIG. 4 is executed.

In this case, the contents of the compare register A are t
(30) = ta + T2 × (30/360) or tt
One of (30) = ta + T3 × (30/360). That is, tt started after the change point of the position signal D
When the calculation of (30) ends before reaching the time t (30), tt (30) is set to the contents of the compare register A.

Since the flag is not set, the signal for driving the transistor Z of the inverter circuit 4 is turned off (as shown in FIG. 7I) and the signal for driving the transistor X is turned on as described above. (Shown in FIG. 7 (g)). At the same time, the drive circuit 12 outputs a control signal for switching from the lower arm to the upper arm so as to chop the signals for driving the transistors U, V, W constituting the upper arm of the inverter circuit 4.
Output to.

In addition, the phase angle 90 from the edge of the position signal D
Time t (90) = t7 + T4 × (90/360) is calculated, and the interrupt routine shown in FIG. 5 is executed at the time when this time t (90) has elapsed (time t9 shown in FIG. 7).

In this case, since the flag is not set, the signal for driving the transistor V of the inverter circuit 4 is turned off and the signal for driving the transistor W is turned on as described above. At the same time, a control signal for switching from the upper arm to the lower arm is output to the drive circuit 12 so as to chop the signals for driving the transistors X, Y, Z forming the lower arm of the inverter circuit 4. To do.

Further, the phase angle 1 from the edge of the position signal D
Time t of 50 degrees t (150) = T7 + T4 × (150/3
60) is calculated, and the interrupt routine shown in FIG. 6 is executed when the time t (150) has elapsed.

In this case, since the flag is not set, the signal for driving the transistor X of the inverter circuit 4 is turned off as described above (shown in FIG. 7 (g)).
The signal that drives the transistor Y is turned on (see FIG. 7).
(Shown in (h)). At the same time, a control signal for switching from the lower arm to the upper arm chopping is output to the drive circuit 12 so that the signals for driving the transistors U, V, W forming the upper arm of the inverter circuit 4 are chopped. To do.

Thus, in this modified embodiment,
An electrical angle of 30 based on the time of one cycle measured this time (time corresponding to an electrical angle of 360 degrees; latest one cycle time)
The time corresponding to the frequency can be calculated and used as the energization switching timing. That is, for example, when the brushless motor 3 has a low rotation speed, even if the microcomputer 20 is at a low speed, the electricity is switched based on the time of one cycle counted this time before the energization switching at the delay point of the electrical angle of 30 degrees. This is because it is possible to calculate the time corresponding to an angle of 30 degrees.

Therefore, in addition to having the same effect as the previous embodiment, it is possible to make the energization switching timing more appropriate at the point where the electrical angle is delayed by 30 degrees from the change point of the position signal D this time, and eventually the rotation unevenness. , Vibration and noise can be further suppressed.

In the above-described embodiment, the energization switching timing of each armature winding is obtained based on the one-phase position signal D, but based on the two-phase or three-phase position signal. Each energization switching timing may be obtained.

[0105]

As described above, according to the brushless motor control method of the present invention, the terminal voltage (induced voltage) of the brushless motor is compared with the reference voltage, and the change in the intersection is detected as a result of the comparison. At the same time, from the change point of this intersection (change point of the position signal D), a predetermined phase angle (electrical angle 3
(0 degrees, 90 degrees, 150 degrees) When calculating the time corresponding to the delay point, the time corresponding to the electrical angle of 30 degrees is calculated before the change point of this time, and the time point at which the calculated time elapses is set as the energization switching timing. Therefore, the microcomputer as the control circuit for controlling the rotation of the brushless motor may have a slow operation speed, that is, the rotation control of the brushless motor can be realized by an inexpensive microcomputer, and the brushless motor can be realized without using the integrating circuit. It is possible to properly switch the energization of, to suppress uneven rotation, vibration and noise, and to prevent step-out and circuit damage to stabilize rotation control and enable efficient operation. The effect is that you can do it.

Further, according to the present invention, the time corresponding to the electrical angle of 30 degrees is calculated even after the change point of the position signal of this time, and this calculation is performed from the change point of this time to the energization switching timing of the electric angle of 30 degrees. When it is in time, the energization is switched at a time corresponding to the currently calculated electrical angle of 30 degrees, so that the energization switching timing can be made more appropriate, and uneven rotation, vibration and noise can be further suppressed. There is an effect.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a control device to which an embodiment of the present invention is applied and to which a brushless motor control method is applied.

FIG. 2 is a schematic time chart diagram for explaining the operation of the controller for the brushless motor shown in FIG.

FIG. 3 is a schematic flowchart illustrating an operation of the brushless motor control device shown in FIG.

FIG. 4 is a schematic flowchart illustrating the operation of the brushless motor control device shown in FIG. 1.

FIG. 5 is a schematic flowchart illustrating the operation of the brushless motor control device shown in FIG.

6 is a schematic flowchart illustrating the operation of the brushless motor control device shown in FIG. 1. FIG.

FIG. 7 is a schematic time chart diagram for explaining a modified embodiment of the present invention.

FIG. 8 is a schematic flowchart illustrating a modified embodiment of the present invention.

FIG. 9 is a schematic flowchart illustrating a modified embodiment of the present invention.

FIG. 10 is a schematic block diagram of a conventional brushless motor control device.

11 is a schematic time chart diagram for explaining the operation of the brushless motor control device shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Double voltage rectifying / smoothing circuit 3 Brushless motor (DC brushless motor) 3a Rotor (of brushless motor 3) 4 Inverter circuit 10 Position detection unit 10a Reference voltage generation circuit 10b Comparison circuit 11, 20 Control circuit (microcomputer) 12 Drive circuit R, S, T Terminal voltage of armature winding D Position signal U, V, W Switching element (upper arm transistor) X, Y, Z Switching element (lower arm transistor)

Claims (3)

[Claims] 1. A DC power supply is switched by an inverter means to be applied to a brushless motor having multi-phase armature windings, and the inverter means is driven based on the position detection of a rotor of the brushless motor to drive the inverter means. A control method for a brushless motor that switches energization of an armature winding, wherein a position signal synchronized with rotation of the brushless motor is obtained by comparing an induced voltage generated in the armature winding with a reference voltage, Based on the position detection point of the signal, one cycle time (a time corresponding to an electrical angle of 360 degrees) or a half cycle time (a time corresponding to an electrical angle of 180 degrees) is measured, and the measured time is always A predetermined number of times are stored, and the time corresponding to the predetermined electrical angle (energization switching timing) is calculated before the current position detection based on the time of one cycle or half cycle that was previously measured. A method for controlling a brushless motor, characterized in that the time corresponding to the calculated predetermined electrical angle is timed from a position detection point this time, and the energization of the armature winding is switched at the end of the time measurement. . 2. A DC power source is switched by an inverter means to be applied to a brushless motor having a multi-phase armature winding, and the inverter means is driven based on the position detection of a rotor of the brushless motor. A control method for a brushless motor that switches energization of an armature winding, wherein a position signal synchronized with rotation of the brushless motor is obtained by comparing an induced voltage generated in the armature winding with a reference voltage, Based on the change point of the signal, one cycle time (time corresponding to an electrical angle of 360 degrees) or half cycle time (time corresponding to an electrical angle of 180 degrees) is timed, and the timed time is always specified. The number of times is stored, and the time corresponding to at least the smallest predetermined electrical angle (the earliest energization switching timing) is calculated based on the time of one cycle or half cycle that was measured last time. While calculating the time before the change point of the position signal, the time corresponding to the calculated predetermined electrical angle is measured from the position detection point this time, and the energization of the armature winding is switched at the end of the time measurement. Is set, the predetermined electrical angle is measured based on the time of one cycle calculated this time, and the calculation of the time corresponding to the predetermined electrical angle at the end of each electric angle is larger than the predetermined time, A method for controlling a brushless motor, wherein the energization is switched using the time calculated after the current position detection point when the switching timing is reached. 3. The brushless motor is a three-phase motor, and an induced voltage generated in one armature winding among the armature windings of the brushless motor is compared with a reference voltage,
2. The time corresponding to the predetermined electrical angles of 30 degrees, 90 degrees, and 150 degrees is calculated from the intersection (position detection point) of the comparison results, and the energization is switched by measuring the calculated time. 2. The method for controlling the brushless motor according to 2.