JPH07284292A - Method and device for controlling brushless motor - Google Patents

Abstract

PURPOSE:To increase the determination range of a reference voltage (specific voltage) required for detecting a rotary position and to properly detect a position regardless of angular frequency in a method and device for controlling a brushless motor. CONSTITUTION:In the method and device for controlling a brushless motor where a DC power supply Vcc is switched by an inverter part 2 and is applied to armature coil windings U, V, and W of a brushless motor 1, the conduction to the armature coil windings U, V, and W is switched for exciting to a specific phase successively, and the brushless motor 1 is rotated and controlled, a position detection part 5 compares a terminal voltage (induction voltage) of the armature coil windings U, V, and W and a specific voltage and then outputs the comparison result to a control circuit 6. Then, the control circuit 6 measures the time between cross points which is the comparison result and at the same time shifts the timing of the next cross point by a specific value based on the measurement time, thus obtaining the timings (ignition timings) of drive signals Ub, Vb, Wb, Xb, Yb, and Zb for driving the shifted timing with the inverter means 2.

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 brushless motor (sensorless DC brushless motor) used as a motor for an air conditioner, and more particularly to a brushless motor for controlling rotation based on rotor position detection. Control method and apparatus therefor.

[0002]

2. Description of the Related Art In order to control the rotation of this sensorless DC brushless motor (hereinafter referred to as brushless motor),
For example, a three-phase brushless motor requires the control device shown in FIG.

In FIG. 1, this control device switches the energization of the armature windings U, V, W of the brushless motor 1 so that the DC power supply Vcc is switched and applied to the armature windings U, V, W. An inverter unit (driving means) 2,
The position of the rotor 1a of the brushless motor 1 is detected based on the terminal voltage (induced voltage) of each armature winding U, V, W,
The position detection unit 3 that outputs this position detection signal and the ignition timing for controlling the rotation of the brushless motor 1 based on this position detection signal are obtained, and the transistor (GTr; switching of the inverter unit 2 is switched by this ignition timing. Element) Ua, Va, Wa, Xa, Ya, Za
And a control circuit (microcomputer or the like) 4 for outputting a drive signal for turning on and off in a predetermined manner.

The control device having the above structure detects the position of the rotor 1a of the brushless motor 1, determines the timing of the drive signal for driving the inverter section 2 based on this position detection signal, and uses this drive signal to determine the timing. Each armature winding U,
The energization of V and W is switched to control the rotation of the brushless motor 1 in a predetermined manner.

By the way, the position detecting section 3 compares each terminal voltage (induced voltage of each phase) waveform with a reference voltage and outputs the comparison result to the control circuit 4 as a position detection signal. As the voltage, 1/2 of the power supply voltage (DC power supply Vcc) is generally used. That is, 1/2 of the Vcc of the armature windings U, V, W can be regarded as.

The brushless motor 1 is driven by, for example, PWM.
When controlling by a control method, the control circuit 4 outputs a drive signal for the inverter unit 2 based on the input position detection signal, and chops the H level of a predetermined drive signal among the drive signals to a plurality of transistors. Is driven on and off in a predetermined manner.

[0007]

However, in the above brushless motor control device, not only the reference voltage must be determined to be 1/2 of the DC power supply Vcc in order to detect the position of the rotor 1a. , Brushless motor 1
The voltage applied to the armature windings U, V, W of the brushless motor 1 differs depending on the rotation frequency of the brushless motor 1, that is, the terminal voltage (induced voltage) waveform of each armature winding U, V, W changes. Since the cross point between the induced voltage waveform and the reference voltage changes, there is also a problem that position detection is not appropriate.

The present invention has been made in view of the above problems, and an object thereof is to be able to determine a reference voltage required for detecting the position of a rotor within a wide range, and an appropriate position regardless of the rotation frequency. It is an object of the present invention to provide a brushless motor control method and a device thereof capable of detection.

[0009]

In order to achieve the above-mentioned object, the present invention switches a direct current power source by a driving means and applies it to a plurality of armature windings of a brushless motor to energize each armature winding. And when controlling the drive means based on the position detection of the rotor of the brushless motor, the terminal voltage (induced voltage) waveform of each armature winding and a predetermined voltage are respectively compared by a comparison means, The point obtained by crossing the edge of the induced voltage waveform and the predetermined voltage is detected by the signal obtained by the comparison result, the time between the detected cross points is measured, and the next cross point is calculated based on the measured time. Is shifted by a predetermined value, and the shifted point is set as an ignition timing necessary for controlling the rotation of the brushless motor.

[0010]

With the above means, when the induced voltage waveform is compared with the predetermined voltage and the cross point between the edge of the induced voltage waveform and the predetermined voltage is detected, the cycle of the cross point has regularity. Therefore, it is possible to detect the rotor position appropriately based on the time between the cross points.

Thus, the predetermined voltage for comparison with the terminal voltage (induced voltage) waveforms of the plurality of armature windings of the brushless motor is not 1/2 of the DC power supply, but is the edge of the induced voltage waveform. If it ’s a level to cross,
Appropriate position detection is possible to obtain the ignition timing required to control the rotation of the brushless motor.

Further, when the rotation frequency of the brushless motor changes, the applied voltage (level) of each armature winding of the brushless motor changes, but the edge of the terminal voltage (induced voltage) waveform of each armature winding and the predetermined voltage If the voltage crosses, proper position detection is possible without being affected by the rotation frequency.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention switches a DC power supply by a driving means and applies it to a plurality of armature windings of a brushless motor,
While switching the energization to each armature winding, the position of the rotor is detected based on the terminal voltage (induced voltage) waveform of each armature winding, and the drive means is controlled based on this position detection signal. In a brushless motor control method and device for controlling the rotation of a brushless motor, when detecting a rotor position by comparing a terminal voltage (induced voltage) waveform of each armature winding of the brushless motor with a predetermined voltage, It is a repetition between the cross point with the cross point obtained by comparing the edge of the induced voltage waveform with the predetermined voltage and between the next cross points,
In other words, paying attention to the fact that it has regularity, the time between cross points included in the comparison result of the induced voltage waveform and the predetermined voltage is measured, and the timing of the next cross point is determined based on the measured time. The timing (firing timing) of the drive signal for controlling the drive means is obtained by shifting by the value.

Therefore, the controller of the brushless motor of the present invention has the structure shown in FIG. In the figure, the same parts as those in FIG.

In FIG. 1, this controller compares terminal voltage (induced voltage) waveforms of armature windings U, V, W of a three-phase brushless motor 1 with a predetermined voltage,
The position detection unit 5 that outputs these comparison results (including the cross point between the induced voltage waveform and the predetermined voltage) and the control circuit 4 shown in FIG. And a control circuit (microcomputer or the like) 6 which uses the point obtained by shifting the next cross point by a predetermined value as the timing of the drive signal of the inverter unit (drive means) 2 based on this measurement time. There is.

The position detecting section 5 comprises at least three comparing circuits 5a, 5b and 5c and a voltage source section 5d for outputting a predetermined voltage, and the predetermined voltage to be compared with the induced voltage waveform is the same induced voltage. A level that crosses the waveform edge may be used, and is not necessarily 1 / DC power supply Vcc.
It does not have to be 2.

Next, the operation of the brushless motor controller having the above structure will be described in detail with reference to the time charts of FIGS. 2 and 3, a is a spike voltage.

First, as in the conventional case, the DC power supply Vcc is switched on the basis of the drive signal (for example, the PWM signal) from the control circuit 6 so that the armature winding U,
It is assumed that the brushless motor 1 is rotationally controlled by applying the voltage to V and W, switching the energization to each armature winding U, V, and W to sequentially excite specific phases.

At this time, the terminal voltages (induced voltages) of the plurality of armature windings U, V, W of the brushless motor 1 have voltage waveforms as shown in FIGS. 2 (a), (b) and (c), for example. The position detection unit 5 compares the induced voltage waveform with a predetermined voltage b (broken lines in FIGS. 7A, 7B, and 7C) and outputs the comparison result to the control circuit 6.

Then, as shown in FIGS. 2 (d), 2 (e) and 2 (f), the comparison result includes the information of the cross points between the respective induced voltage waveforms and the predetermined voltage level. The control circuit 6 detects the timing of the cross point in consideration of the PWM cycle. The PWM cycle is taken into consideration in order to correct the comparison timing of the chopper waveform (shown in FIGS. 2 (d), 2 (e), and 2 (f)) to obtain the timing that crosses the edge of the induced voltage waveform. .

The control circuit 6 generates the waveform timing of the cross point (shown in FIG. 2 (g)), measures the time between the cross points, and shifts the next cross point based on the measured time. The shifted timing is used as the rising timing of the drive signal for driving the inverter unit 2.

Specifically, as shown in FIG. 2 (g), the timing at which the next cross point a1 is shifted to the right on the paper based on the measurement time t1 is obtained, and this shift amount is t1 / 2.
Is. In addition, the next cross point a based on the measurement time t2
The timing of shifting 2 to the right on the paper surface is obtained, and the shift amount is t2 / 2. Similarly, the timings at which the cross points a3 to a7 are sequentially shifted to the right are obtained, and the timings at which the cross points after the cross point a7 are sequentially shifted to the right are similarly obtained.

In this case, since the predetermined voltage b to be compared with the induced voltage waveform corresponds to the voltage (so-called neutral point) at the connection point (star connection point) of each armature winding U, V, W, each The measurement times t1 and t2 are the same, and the same is true for each subsequent measurement time, that is, the cross points are equidistant.

By the way, as shown in FIG. 3, when the predetermined voltage to be compared with the induced voltage waveform in the position detecting section 5 is higher than 1/2 of the DC power source Vcc, the interval between certain cross points becomes narrow (see FIG. (See (d)), but the interval between the next cross points becomes wider on the contrary. Explaining with reference to FIG. 2G, the measurement time t2 becomes short, but the measurement time t1 becomes long, and the timing of each cross point is the repetition of t2 and t1.

Since the measurement time t2 becomes short even if the measurement time t1 is long, the next cross point a1 shifts to the left on the paper surface, and if this cross point a1 is shifted to the right on the paper surface by 1/2 of the measurement time t1, The timing of this shift is shown in FIG.
The timing shown by the broken line, that is, the same as the timing described above. Similarly, when the next cross point a2 (shown in FIG. 2 (g)) is shifted to the right in the figure by 1/2 of the measurement time t2, this shifted timing is shown in FIG. 2 (g).
The timing shown by the broken line, that is, the same as the timing described above.

When the predetermined voltage to be compared with the induced voltage waveform in the position detecting section 5 is lower than 1/2 of the DC power supply Vcc, the measurement time t1 is shortened but the measurement time t2 is lengthened contrary to the above. The timing of each cross point is the repetition of t1 and t2. Therefore,
When the cross points a1 to a7 are right-shifted by the method described above, the timing of this shift is shown in FIG.
The timing is indicated by the broken line.

The control circuit 6 which has obtained the above-mentioned timing (so-called ignition timing) is based on the same timing as in FIG.
Drive signals Ub, Vb, Wb, shown in (h) to (m),
It outputs Xb, Yb, and Zb to drive the inverter unit 2. In the case of the PWM control method, the drive signal Ub,
The H level of Vb and Wb is chopped at a predetermined frequency.

As described above, the predetermined voltage b to be compared with the induced voltage waveform does not have to be 1/2 of the DC power supply Vcc, and if the predetermined voltage b is stable within the range crossing the edge of the induced voltage waveform. Since it is good, the predetermined voltage b (reference voltage described in the conventional example) can be appropriately determined within the cross range, and the circuit configuration of the voltage source unit 5d is easy.

Further, the brushless motor 1 has a different rotation frequency, and each armature winding U, V,
If the applied voltage of W changes, that is, the height (level) of the induced voltage waveform changes, the cross point with the predetermined voltage b differs. However, if the predetermined voltage b is within the range where it crosses the edge of the induced voltage waveform, the position detection of the rotor 1a becomes appropriate regardless of the rotation frequency, and the armature windings U, V, and V of the brushless motor 1 are detected. It is possible to obtain the timing of the drive signal for driving the inverter unit 2 in order to properly excite W sequentially.

Even if the brushless motor 1 is not controlled by the PWM control method, the same action and effect can be obtained.

[0031]

As described above, according to the present invention, the DC power source is switched by the inverter means and applied to the plurality of armature windings of the sensorless DC brushless motor (hereinafter referred to as brushless motor), and each electric machine is driven. In the brushless motor control method and device for switching the energization to the child winding to control the rotation of the brushless motor, the terminal voltage (induced voltage) of each armature winding is compared with a predetermined voltage, and the comparison result is compared. Control circuit (microcomputer)
This microcomputer measures the time between cross points, which is the comparison result, and shifts the timing of the next cross point by a predetermined value based on the measured time to drive the inverter means. Since the timing (firing timing) is obtained, the predetermined voltage to be compared with the induced voltage waveform in order to detect the position of the rotor can be appropriately determined within the range crossing the edge of the induced voltage waveform. Yes, that is, the circuit configuration for obtaining a predetermined voltage (so-called reference voltage) is easy, and the rotation frequency of the brushless motor changes, that is, the terminal voltage (induced voltage) waveform of the armature winding of the brushless motor changes. However, there is a useful effect that the position of the rotor can be accurately detected and the excitation of the armature winding can be appropriately performed.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a brushless motor control device according to an embodiment of the present invention.

FIG. 2 is a schematic time chart diagram for explaining the operation of the control device shown in FIG.

FIG. 3 is a schematic time chart diagram for explaining the operation of the control device shown in FIG.

FIG. 4 is a schematic block diagram of a conventional brushless motor control device.

[Explanation of symbols]

1 Brushless Motor (Sensorless DC Brushless Motor) 1a Rotor 2 Inverter Section (Drive Unit) 4,6 Control Circuit (Microcomputer etc.) 5 Position Detection Section 5a, 5b, 5c Comparison Circuit 5d Voltage Source Section a Spike Voltage b Predetermined Voltage (Equivalent to reference voltage) U, V, W Armature winding

Claims (3)

[Claims] 1. A DC power source is switched by a driving means to be applied to a plurality of armature windings of a brushless motor to switch energization to each armature winding, and based on position detection of a rotor of the brushless motor. When controlling the drive means by means of the above, the comparison means compares the terminal voltage (induced voltage) waveform of each armature winding with a predetermined voltage, and the signal obtained by the comparison result determines the edge of the induced voltage waveform. The point crossing the predetermined voltage is detected, the time between the detected cross points is measured, the next cross point is shifted by a predetermined value based on the measured time, and the shifted point is the brushless motor. A method for controlling a brushless motor, characterized in that the ignition timing is required to control rotation of the motor. 2. A DC power source is switched by an inverter means and applied to a plurality of armature windings of a brushless motor,
A control method of a brushless motor for controlling rotation of a brushless motor that drives the inverter means based on position detection of a rotor of the brushless motor while switching energization to each armature winding. The terminal voltage (induced voltage) waveform and the predetermined voltage are respectively compared by a comparing means, and the cross point between the edge of the induced voltage waveform and the predetermined voltage is detected by the signal obtained by the comparison result, and the detected cross point is detected. Control of a brushless motor characterized in that the time between the two is measured, the next cross point is shifted by a predetermined value based on the measured time, and the timing of the shifted point is set as the timing of the drive signal of the inverter means. Method. 3. A DC power source is switched by an inverter means and applied to a plurality of armature windings of a brushless motor,
A controller of a brushless motor that controls the rotation of a brushless motor that drives the inverter unit based on the position detection of the rotor of the brushless motor while switching the energization of each armature winding. Comparison means for respectively comparing a terminal voltage (induced voltage) waveform and a predetermined voltage, voltage source means for outputting the predetermined voltage, and a cross point between the edge of the induced voltage waveform and the predetermined voltage by inputting the comparison result. And the time between the detected cross points is measured, the next cross point is shifted by a predetermined value based on the measured time, and a drive for driving the inverter means at the timing of the shifted point. A controller for a brushless motor, comprising: a control unit that outputs a signal.