JPH09285179A - Control of brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent reverse current from appearing in switching a chopping of an upper and a lower arm when controlling the rotation of a brushless motor. SOLUTION: AC of an AC power supply 1 is rectified by a voltage doubler rectifier circuit 2 into DC of double voltage, which is supplied to armature windings of a brushless motor 4 through a transistor module section 3. In this case, a controlling circuit 10 detects the position of a rotor 4a, based on a position signal from a position detecting section 5. Based on the detection result, transistors U, V, W of an upper arm and transistors X, Y, Z of a lower arm of a transistor module section 3 are on/off-controlled. One of the arms is chopped and then a chopping of the arms is switched wit a given timing. At this point, the termination of spike voltage appearing in the armature windings of the burshless motor 4 is detected by the position signal from the position detecting section 5. After the detection of the termination of the spike voltage or when the passage of a given electric angle after the former position detection is behind the termination of the spike voltage, a chopping of the upper and the lower arm is switched after the passage of a given electric angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to rotation control of a sensorless DC brushless motor (hereinafter referred to as a brushless motor) used in a compressor of an air conditioner, and more particularly, it drives a brushless motor to move a transistor module unit up and down. The present invention relates to a brushless motor control method that stabilizes rotation control of a brushless motor by preventing noise when switching the chopping of the upper and lower arms when chopping the transistors of the arm.

[0002]

2. Description of the Related Art When controlling the rotation of a brushless motor of this type, for example, a three-phase motor, a control device shown in FIG. 6 is required. In the figure, this control device rectifies the AC voltage of an AC power supply (for example, AC 100 V) 1 into a voltage doubler (for example, 280 V) by a voltage doubler rectifier circuit 2, and the voltage Vdc thus rectified is a switching element (transistor) U. ，
The transistor module unit 3 in which V, W, X, Y, and Z are bridge-connected is switched and applied to the armature winding of the brushless motor 4.

The terminal voltage (induced voltage) of the brushless motor 4 is input to the position detecting section 5, and the terminal voltage and the reference voltage Vd are input.
The position signal of the rotor 4a is obtained by comparing with c / 2. Therefore, the position detection unit 5 divides the power supply voltage Vdc of the transistor module unit 3 in half to divide the reference voltage Vdc / 2.
And a comparison circuit 5b that compares the terminal voltage (induced voltage) with the reference voltage Vdc / 2 and outputs a position signal synchronized with the rotation of the brushless motor 4 to the control circuit 6. .

The control circuit 6 detects the position of the rotor 4a of the brushless motor 4 based on the one-phase position signal. In this case, when the induced voltage of the terminal voltage R is rising, the first rising edge of the position signal after energization switching is used as position detection, and when the induced voltage is falling, the first falling edge of the position signal after energization switching is performed. The edge is the position detection.

Further, in order to switch the energization of each armature winding of the brushless motor 4 on the basis of the above position detection, each transistor U, V, W, X, Y, Z of the transistor module section 3 is switched. A drive signal that turns on and off is output, while this drive signal is chopped with a chopping signal having a variable duty ratio. The control circuit 6 is composed of a microcomputer and a drive circuit.

In the control device of the one-phase position detection system, as shown in FIG. 7A, for example, the terminal voltage R is compared with the reference voltage Vdc / 2, and the position signal changing at the intersection of the comparison results. (See FIG. 7B).

The control circuit 6 which receives the position signal detects the first rising edge (falling edge when the induced voltage falls) of the position signal after the spike voltage k (switching energization), and detects the detected edge. 4a as the position detection point, and based on this position detection point, the energization switching time of each phase (electrical angle 30 degrees, 90 degrees, 150 degrees from the position detection point)
Time) is calculated.

In this case, the time of the position detection interval is obtained, and the time corresponding to the electrical angles of 30 °, 90 ° and 150 ° is calculated based on this time, and 3 times from the position detection point.
Times of 0, 90 and 150 degrees are calculated. A drive signal for switching the conduction state of each of the transistors U, V, W, X, Y, and Z of the transistor module unit 3 after the calculated time from the position detection point (see FIGS. 7C to 7H). To occur. Since these transistors U, V, W, X, Y, and Z are driven by these drive signals, energization of the armature winding current of the brushless motor 4 is switched, and the brushless motor 4 is rotationally controlled.

Further, as shown in FIGS. 7 (c) to 7 (h), in the case of the PWM control method, the control circuit 6 chops the drive signal of the transistor module section 3 with a chopping signal having a predetermined duty ratio.

In this case, as shown in FIGS. 7C to 7H, one of the upper arm transistors U, V, W or the lower arm transistors X, Y, Z is chopped, and Switch the chopping of the upper and lower arms. For example, as shown by the broken line in FIG. 7, when the chopping switching of the upper and lower arms is performed in accordance with the switching of energization of the brushless motor 4, only the latter half of driving of the transistors U, V, W, X, Y, Z is performed. Can be chopped.

As described above, the time at which each armature winding current of the brushless motor 4 is switched is calculated based on the position signal, the energization is switched at the calculated time, and the chopping duty ratio (on / off ratio) is changed. By doing
The brushless motor 4 can be rotationally controlled to a predetermined rotational speed.

[0012]

However, in the above brushless motor control method, a reverse current is generated when chopping the upper and lower arms, and this reverse current increases, so that not only the efficiency decreases but also the correlation imbalance. Occurs, which adversely affects the rotation control of the so-called brushless motor 4.

That is, the chopping switching of the upper and lower arms is performed during the spike voltage k, and a reverse current due to the spike voltage k flows through the diode of the transistor module section 3.

The present invention has been made in view of the above problems, and an object thereof is to provide a brushless motor control method capable of preventing reverse current due to switching of chopping of upper and lower arms and preventing correlation imbalance. To do.

[0015]

In order to achieve the above object, the present invention provides a DC power supply through a transistor module means to an armature winding of a brushless motor to control the rotation of the brushless motor. The position of the rotor of the brushless motor is detected by a position signal obtained by comparing the voltage of the armature winding of the brushless motor and the reference voltage, and the switching element of the transistor module means is detected based on the detected position. ON / OFF driving is performed to switch the energization of the armature winding, and the switching means of either one of the upper and lower arms of the transistor module means is driven by a chopping signal having a variable duty ratio, and the upper and lower arms are driven. Is a method for controlling a brushless motor that switches the chopping of a predetermined position according to the position signal. Wherein detecting the end of the spike voltage generated upon energization switching the armature windings, it is characterized in that to switch the chopping of the upper and lower arms after detection spike voltage ends.

Further, according to the brushless motor control method of the present invention, the position signal is used to detect the end of the spike voltage generated when the energization of the armature winding is switched, while the predetermined electrical angle preset from the position detection is detected. When the time elapses after the end of the detected spike voltage, the chopping of the upper and lower arms is switched after the elapse of the predetermined electrical angle. In this case, the predetermined electrical angle is 18
A value smaller than 0 degrees is preferable.

According to the present invention, when DC power is supplied to the armature winding of the brushless motor through the transistor module means to control the rotation of the brushless motor, one winding voltage of the armature winding of the brushless motor is controlled. And a reference voltage are compared, and the position of the rotor of the brushless motor is detected by a position signal for one phase based on the comparison result, while the energization switching time of the brushless motor is detected based on the interval time of the position detection. Based on the calculated time, the switching element of the transistor module means is turned on and off to switch the energization, and the switching means of either one of the upper and lower arms of the transistor module means is variable. Driven by the ratio chopping signal, and the chopping of the upper and lower arms is predetermined. A method of controlling a brushless motor changing Ri, detecting the end of the spike voltage generated upon energization switching of the armature winding by the position signal,
The chopping of the upper and lower arms is switched after the detection spike voltage is finished, and a time corresponding to a predetermined electrical angle is calculated based on the time of the position detection interval, and the calculated time is set to the chopping switching time of the upper and lower arms. It is characterized in that the chopping switching time of the upper and lower arms in the other phase is predicted by adding and the chopping of the upper and lower arms is switched when the predicted time has elapsed.

In this case, when calculating the time corresponding to the predetermined electrical angle, one is based on the interval time of the previous position detection and the other one is based on the interval time of the current position detection. It is good to calculate it.

According to the above means, for example, in the case of the one-phase position detection method, the position of the rotor is determined based on the comparison result (position signal) between one terminal voltage of the armature winding of the brushless motor and the reference voltage. Upon detection, the position detection time is detected and the time at the same interval is calculated.

The energization switching time of each phase is calculated based on this time and time, and the switching element of the transistor module means is turned on and off so as to switch the energization of the brushless motor at this time.

At this time, the end of the spike voltage (the first rising edge or the falling edge after switching the energization) is detected by the position signal, and the chopping of the upper and lower arms is switched after the end of the spike voltage. When the detection of the end of the spike voltage is before a predetermined electric angle (for example, 165 degrees) has passed since the previous position detection, the chopping of the upper and lower arms is switched after the predetermined electric angle.

Further, the chopping switching time is detected, and the time until the chopping switching of the upper and lower arms in the remaining phases is calculated based on the time of the position detection interval. In the phase of, the chopping switching time of the upper and lower arms is predicted. It should be noted that it is assumed that the spike voltage of the other phase ends after the calculation of the time until the chopping switching of the upper and lower arms.

Since the chopping of the upper and lower arms is switched with the lapse of the time thus obtained, the chopping of the upper and lower arms is not switched during the spike voltage.

In the case of the three-phase position detection method, the end of the spike voltage in each phase is detected by the position signal of each phase, and the chopping of the upper and lower arms is switched after the end of this spike voltage.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention focuses on the fact that when switching the chopping of the upper and lower arms of the transistor module part for driving the brushless motor, reverse current can be prevented except when a spike voltage is generated.

Therefore, the control device to which the brushless motor control method of the present invention is applied has the configuration shown in FIG. In FIG. 1, the same parts as those in FIG.

In FIG. 1, in addition to the function of the control circuit 6 shown in FIG. 6, this brushless motor control device uses the position signal from the comparison circuit 5b of the position detection section 5 to determine when the spike voltage ends. Is detected, and the chopping of the upper and lower arms is switched after the spike voltage is completed (or after a predetermined electrical angle has passed from the position detection), or the chopping is switched after the spike voltage is completed, and when the predetermined electrical angle is reached after the chopping is switched. A control circuit (microcomputer and drive circuit) 10 for switching the chopping of the arm is provided.

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 5. First, the control circuit 10 rotates the brushless motor 4 by the same processing as in the conventional case. Control.

In this case, as described in the conventional example, the control circuit 10 detects the position of the rotor 4a based on the position signal, measures the interval time of this position detection, and detects the electrical angle of 30 degrees or 90 degrees from the position detection time. And the time corresponding to 150 degrees are calculated, and this calculated time is set as the energization switching time of the brushless motor 4.

Further, the control circuit 10 detects the first edge (rising edge or falling edge) of the position signal after switching the energization, and judges this detection edge timing as the end of the spike voltage k.

When the induced voltage of the terminal voltage R rises, it is determined that the first falling edge of the position signal after the energization switching is the end of the spike voltage k, and when the induced voltage falls, the position after the energization switching. The first rising edge of the signal is determined to be the end of the spike voltage k.

When the spike voltage k ends or the set time is determined (step ST1), when the spike voltage k ends, the process proceeds to step ST2 to set the spike voltage k flag while setting the set time. If so, the process proceeds to step ST3, and the set time flag is set. The set time is a time corresponding to a predetermined electrical angle (a value smaller than 180 degrees; for example, 165 degrees) from the position detection.

Subsequently, after setting the spike voltage flag, it is judged whether or not the set time flag is already set (step ST4), and when the set time flag is not set, the processing shown in FIG. 3 is ended. In addition, after setting the set time flag, it is determined whether or not the spike voltage flag is already set (step ST
5) If the spike voltage flag is not set, the process shown in FIG. 3 is terminated.

Here, assuming that the present time is the timing of the broken arrow c in FIG. 2 (that is, the set time), after setting the setting flag (step ST3), it is determined whether or not the spike voltage flag is set. (Step ST
5). At this time, since the end of the spike voltage k has already been detected and the spike voltage flag has been set,
In step ST5 to ST6, the chopping of the upper and lower arms is switched, and for example, in the case shown in FIG. 2, the chopping of the upper arm is switched to the chopping of the lower arm.

The set time (the time of the predetermined electrical angle (165 degrees) from the position detection) may not be the timing of the broken line arrow c in FIG. 2, that is, the end of the spike voltage k. In this case, when the end of the spike voltage k is detected, the set time flag has already been set,
From step ST4 to ST6, the chopping of the upper and lower arms is switched in the same manner as described above.

Subsequently, after the chopping switching of the upper and lower arms, an upper and lower arm switching flag for performing the processing shown in FIGS. 4 and 5 is set (step ST7).

Subsequently, the chopping switching time ta of the upper and lower arms is detected (step ST8), and a predetermined value α (for example, the delay time of the element for switching the upper and lower arms) is added to this time ta (step ST9). The added time ts is used as a mask for position detection (step ST10).

Next, the time T of the position detection interval of the previous time measurement
Based on 1, the time corresponding to an electrical angle of 60 T1 × 60 /
180 is calculated, and this time is added to the time ta to obtain the next chopping switching time t of the upper and lower arms.
60 is calculated (step ST11). The predicted time t60 corresponds to the end of the spike voltage in the other phase.

Then, in order to execute the next chopping switching of the upper and lower arms by the processing shown in FIG. 4, the calculated time t60 is set in the conveyor register (step S).
T12). Further, since the chopping switching of the first upper and lower arms is performed, the spike voltage flag and the set time flag are reset (step ST13).
The calculated time t60 (time t120 described later)
When has passed, the set time flag is set in the process of step ST3.

If the upper / lower arm switching flag is set at the current timing of the broken line arrow d in FIG. 2, that is, at the calculation time t60, the processing shown in FIG. 4 is executed to first chop the upper and lower arms. Switching (step ST20), in this case switching from lower arm to upper arm chopping.

Subsequently, while the chopping switching time ta of the upper and lower arms is detected (step ST21),
The time T2 × 120/180 corresponding to the electrical angle 120 is calculated based on the time T2 of the position detection interval of the present time measurement, and this time is added to the time ta and the next chopping switching time t120 of the upper and lower arms. Is calculated (step ST22). Note that this predicted time t1
20 applies after termination of the spike voltage in the remaining phases. Further, in the calculation of the time corresponding to the electrical angle of 120 degrees, the time T1 of the previous position detection interval may be used, but it is extremely likely that the time T2 of the current position detection interval has been obtained, and it is as new as possible. It is preferable to use information.

Then, in order to execute the next chopping switching of the upper and lower arms by the processing shown in FIG. 5, the calculated time t120 is set in the conveyor register (step ST23).

If the upper and lower arm switching flag is set at the timing of the broken line arrow f in FIG. 2, that is, at the above calculation time t120, the processing shown in FIG. 5 is executed to switch the chopping of the upper and lower arms ( In step ST30), the upper arm is switched to the lower arm chopping in this case. In the process shown in FIG.
Resets the upper and lower arm switching flags and clears the conveyor register, etc.

When the end of the next spike voltage k is detected, execution is started from the processing shown in FIG. 3 and the chopping of the upper and lower arms is switched as described above, and then the processing shown in FIG. The chopping of the arms is switched, and the processing shown in FIG. 5 is executed to switch the chopping of the upper and lower arms.

In this way, the end of the spike voltage k is detected, and after the end of the detected spike voltage, or when the predetermined electrical angle (165 degrees) has elapsed since the previous position detection, it is later than the end of the detected spike voltage. After the predetermined electrical angle has elapsed, the chopping of the upper and lower arms is switched, and the time corresponding to the predetermined electrical angle from this chopping switching (see FIG. 2).
(See times t60 and t120), the chopping of the upper and lower arms in another phase is switched.

Therefore, reverse current due to chopping switching of the upper and lower arms can be prevented, no correlation imbalance occurs, and efficiency does not decrease. Also,
Since the position detection mask is performed only for a predetermined time after the spike voltage k, erroneous position detection can be prevented.

In the above embodiment, the case of the one-phase position detection method has been described, but it can be applied to the three-phase position detection method. In this case, the position detection unit 5 needs three comparison circuits, and each comparison circuit has a terminal voltage R, S, T of the armature winding of the brushless motor 4 and a reference voltage Vdc / 2.
And the position signal of these comparison results is compared with the control circuit 10
Output to

The control circuit 10 detects the position of the rotor 4a by three position signals to switch the energization of the brushless motor 4, and at the same time, each position signal causes the spike voltage k of each phase to be changed.
Of the upper and lower arms is switched after the detection of the end of the above, or when the predetermined electrical angle (for example, 165 degrees) has elapsed after the previous position detection is later than the end of the detected spike voltage, the chopping of the upper and lower arms is switched. .

Therefore, it is not necessary to calculate the chopping switching times t60 and t120 (see FIG. 2) of the upper and lower arms, and the software can be simplified.

[0050]

As described above, according to the present invention, the position of the rotor is detected by the position signal obtained by comparing the terminal voltage of the armature winding of the brushless motor with the reference voltage. Based on the detection, the transistor in the transistor module is turned on and off, while the transistor in one of the upper and lower arms of the transistor module is chopped at a variable duty ratio to rotate the brushless motor in a predetermined manner. A control method of a brushless motor for controlling, wherein the end of a spike voltage is detected by the position signal, and after the end of this spike voltage, or when a predetermined electrical angle has elapsed since the previous position detection, it is later than the end of the detected spike voltage. Sometimes, the chopping is switched after the predetermined electrical angle has passed, so the upper and lower arm check It is possible to prevent reverse current due mappings switching does not occur correlation unbalanced,
There is an effect that efficiency does not decrease.

According to the present invention, in the case of the one-phase position detection method, when the chopping of the upper and lower arms is switched after the end of the spike voltage of one phase by the above method, the switching time is detected, while the time of the position detection interval is detected. Since the time corresponding to the predetermined electrical angle is calculated based on the above, and the calculated time is added to the chopping switching time to switch the chopping of the upper and lower arms, it is possible to prevent the reverse current as described above. In addition, the correlation imbalance does not occur and the efficiency does not decrease, and the position detection circuit of the control device can be simplified.

[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.

3 is a schematic flowchart for explaining the operation of the brushless motor control device shown in FIG. 1. FIG.

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

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

FIG. 6 is a schematic block diagram of a conventional control device for a brushless motor.

FIG. 7 is a schematic time chart diagram for explaining the operation of the brushless motor control device shown in FIG. 6.

[Explanation of symbols]

1 AC power supply 2 Double voltage rectifier circuit 3 Transistor module part 4 Brushless motor (sensorless DC brushless motor) 4a Rotor (of brushless motor 4) 5 Position detection part 5a Reference voltage generation circuit 5b Comparison circuit 6,10 Control circuit (microcomputer) ) Vdc reference voltage k spike voltage R, S, T terminal voltage of armature winding

Claims (5)

[Claims] 1. When a DC power source is supplied to an armature winding of a brushless motor through a transistor module means to control the rotation of the brushless motor, the voltage of the armature winding of the brushless motor is compared with a reference voltage. The position of the rotor of the brushless motor is detected by the obtained position signal, and the switching element of the transistor module means is turned on and off based on the detected position to switch the energization of the armature winding. At the same time, a method of controlling a brushless motor, wherein a switching means of one of the upper and lower arms of the transistor module means is driven by a chopping signal having a variable duty ratio, and the chopping of the upper and lower arms is switched in a predetermined manner, Spikes that occur when the energization of the armature winding is switched by the position signal The method of the brushless motor, characterized in that detecting the end of the pressure, and to switch the chopping of the upper and lower arms after detection spike voltage ends. 2. When the DC power is supplied to the armature winding of the brushless motor through the transistor module means to control the rotation of the brushless motor, the voltage of the armature winding of the brushless motor is compared with the reference voltage. The position of the rotor of the brushless motor is detected by the obtained position signal, and the switching element of the transistor module means is turned on and off based on the detected position to switch the energization of the armature winding. A method for controlling a brushless motor, in which the switching means of one of the upper and lower arms of the transistor module means is driven by a chopping signal having a variable duty ratio, and the chopping of the upper and lower arms is switched in a predetermined manner, Spikes that occur when the energization of the armature winding is switched by the position signal While detecting after the end of the pressure, if the predetermined electrical angle set in advance from the position detection is after the end of the detected spike voltage, the chopping of the upper and lower arms is switched after the predetermined electrical angle. A method for controlling a brushless motor, characterized in that 3. The method of controlling a brushless motor according to claim 2, wherein the predetermined electrical angle has a value smaller than 180 degrees. 4. When a DC power supply is supplied to the armature winding of the brushless motor through the transistor module means to control the rotation of the brushless motor, one of the winding voltage of the armature winding of the brushless motor and The position of the rotor of the brushless motor is detected by comparing the reference voltage with the position signal for one phase based on the comparison result, and the energization switching time of the brushless motor is set based on the position detection interval time. And switching on the switching element of the transistor module means based on the calculated time,
A brushless motor that is turned off to switch energization, drives the switching means of one of the upper and lower arms of the transistor module means with a chopping signal having a variable duty ratio, and switches the chopping of the upper and lower arms to a predetermined value. The method of detecting the end of the spike voltage generated at the time of switching the energization of the armature winding by the position signal, switching the chopping of the upper and lower arms after the end of the detected spike voltage, and the position detection interval. The time corresponding to the predetermined electrical angle is calculated based on the time of, and the calculated time is added to the chopping switching time of the upper and lower arms to predict the chopping switching time of the upper and lower arms in the other phase, Switch the chopping of the upper and lower arms as time passes A method for controlling a brushless motor, characterized in that 5. When calculating the time corresponding to the predetermined electrical angle, one is based on the interval time of the previous position detection and the other one is based on the interval time of the current position detection. The method of controlling the brushless motor according to claim 4, which is calculated.