JP2003219674A - Controller of brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low vibration, low noise and high efficiency controller of a brushless motor. <P>SOLUTION: The modulation signal of a brushless motor driven through an inverter 2 is a pulse width modulation signal at the time of low speed operation having a significant effect on torque pulsation and variation of r.p.m., and is a conduction angle modulation signal at the time of high speed operation having a relatively insignificant effect on torque pulsation and variation of r.p.m. but requiring a high efficiency. Since the controller can make a switch between driving through pulse width modulation and driving through conduction angle modulation depending on the r.p.m. of the motor 3, torque pulsation and variation of r.p.m. can be suppressed at the time of low speed operation and accelerating/decelerating operation of the motor 3 can be realized while suppressing switching loss at the time of high speed operation. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a motor used in electric equipment and the like. 2. Description of the Related Art Pulse width modulation is widely used as a speed control device for a brushless motor driven by an inverter circuit. Hereinafter, a conventional control device for a brushless motor driven by an inverter circuit will be described. FIG. 4 is a drive circuit diagram of a brushless motor driven by acceleration / deceleration only by pulse width modulation. A control device of the brushless motor includes a motor 3 having three-phase windings of U-phase, V-phase, and W-phase. , A power supply 1 and an inverter 2 including six switching elements and six diodes for driving the motor 3. The position of the rotor of the motor 3 is detected by a position detection circuit 4, and a phase energization signal generated by a phase energization signal generation circuit 5 and a pulse width modulation waveform generated by a pulse width modulation waveform generation circuit 6 are used. In addition, the inverter 2 is driven via the drive circuit 10 based on the switching pattern generated by the switching pattern generation circuit 9, and the pulse width modulation DUTY is changed from 0% to 100% to change the motor. 3 acceleration / deceleration operation is possible. FIG. 2 shows a relationship between a rotor position detection signal pattern, a phase conduction signal pattern, a switching pattern, and a pulse width modulation duty ratio during pulse width modulation and an average output voltage. The position detection signal pattern in the position detection circuit 4, the phase conduction signal pattern in the phase conduction signal generation circuit 5, and the switching pattern in the inverter 2 are respectively the position detection signal pattern, the phase conduction signal pattern, and the switching pattern shown in FIG. It corresponds to. Further, as shown in FIG. 2, the average output voltage is proportional to the pulse width modulation duty. That is, the torque of the motor is proportional to the pulse width modulation duty. FIG. 5 is a drive circuit diagram of a brushless motor which is accelerated / decelerated only by energization angle modulation. U phase, V
It comprises a motor 3 having three-phase and W-phase windings, a power supply 1 for the motor 3, an inverter 2 including six switching elements for driving the motor 3 and six diodes. [0007] The position of the rotor of the motor 3 is detected by a position detection circuit 4, and a phase energization signal generated by a phase energization signal generation circuit 5 and an energization angle modulation waveform generated by an energization angle modulation generation circuit 7 are obtained. In addition, the switching pattern generated by the switching pattern generation circuit 9 drives the inverter 2 via the drive circuit 10. Further, by changing the energization angle between 60 degrees and 120 degrees, the acceleration / deceleration operation of the motor 3 is enabled. The position detection signal pattern in the position detection circuit 4, the phase conduction signal pattern in the phase conduction signal generation circuit 5, and the switching pattern in the inverter 2 during the conduction angle modulation are the position detection signal patterns shown in FIG. , Phase energization signal patterns and switching patterns. Further, as shown in FIG. 3, the average output voltage is proportional to the energizing angle with the intercept being 60 degrees. That is, the torque of the motor is proportional to the conduction angle when the conduction angle is between 60 degrees and 120 degrees. When the motor is accelerated / decelerated only by the pulse width modulation, the ON / OFF operation at the carrier frequency of the pulse width modulation is performed in addition to the switching loss when the energized phase of the motor winding is switched. -The switching loss at the time of OFF is increased, which causes a reduction in efficiency. Furthermore, at the time of high-speed rotation, there is a problem that the motor current increases and the loss of the entire power element increases. Further, when the motor is accelerated / decelerated only by the energization angle modulation, the switching loss only switches the energized phase of the motor winding, but when the energization is continuously turned off, the average torque of the motor is the same. The energization angle modulation has a problem that the torque pulsation becomes larger than the pulse width modulation since the energization time is longer than the continuous energization OFF time in the pulse width modulation. [0011] The present invention provides low vibration, low vibration, high speed operation of the motor while suppressing torque pulsation and rotation speed fluctuation during low speed operation and switching loss during high speed operation.
An object of the present invention is to provide a low-noise and high-efficiency brushless motor control device. [0012] A modulation signal of a brushless motor driven by an inverter circuit is converted into torque pulsation,
Pulse-width modulation is used for low-speed operation that has a relatively large effect on rotation speed fluctuations, and energization angle modulation is used for high-speed operation that requires high efficiency with relatively small effects on torque pulsation and rotation speed fluctuations. As described above, by using a control device that can switch between driving by pulse width modulation and driving by energization angle modulation in accordance with the rotation speed of the motor, torque pulsation and fluctuations in rotation speed during low-speed operation can be suppressed, and high-speed operation can be achieved. During operation, acceleration / deceleration operation of the motor can be performed while suppressing switching loss. An embodiment of the present invention is directed to a brushless motor, an inverter for driving the brushless motor, and a position detecting circuit for detecting a rotational position of a rotor of the brushless motor. A phase energization signal generation circuit that generates an energization signal that energizes the phase of the brushless motor based on a signal of the position detection circuit; a pulse width modulation waveform generation circuit that generates a pulse width modulation signal from a command voltage; An energization angle modulation generation circuit that generates an energization angle modulation signal from a voltage and a signal of the position detection circuit, and calculates the speed of the brushless motor from a signal of the position detection circuit. A modulation waveform switching circuit for selecting a signal of the energization angle modulation circuit during high-speed operation, and a signal of the phase energization signal generation circuit. A switching pattern generating circuit for generating an inverter switching pattern from a signal of the modulation wave switching circuit, and a drive circuit for driving a switching element of the inverter. In this case, acceleration and deceleration of the motor can be performed while suppressing torque pulsation and fluctuations in the number of revolutions, and switching loss during high speed operation. A specific example of a control device for a brushless motor according to the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a motor control device.
It comprises a motor 3 having three-phase windings of U-phase, V-phase and W-phase, a power supply 1 of the motor 3 and an inverter 2 for driving a motor composed of six switching elements and six diodes. . The position of the rotor of the motor 3 is detected by a position detection circuit 4, and a phase conduction signal generation circuit 5 generates a phase conduction signal based on the position detection signal from the position detection circuit 4. The pulse width modulation waveform generation circuit 6 generates a pulse width modulation signal from the command voltage, and the energization angle modulation generation circuit 7 generates an energization angle modulation signal from the command voltage and the signal of the position detection circuit 4. The modulation waveform switching circuit 8 includes a position detection circuit 4
The signal of the pulse width modulation waveform generation circuit 6 and the signal of the energization angle modulation circuit 7 are selected by calculating the number of rotations of the motor 3 from the signals of the above. The inverter 2 is driven via the drive circuit 10 according to the switching pattern generated by the switching pattern generation circuit 9 based on the pulse width modulation signal or the energization angle modulation signal selected by the modulation waveform switching circuit 8. The modulation signal selected by the modulation waveform switching circuit 8 is driven by pulse width modulation during low speed operation to suppress torque pulsation and rotation speed fluctuation, and is driven by energized angle modulation during high speed operation requiring high efficiency. This suppresses the switching loss of the power element. Although the torque pulsation and the rotation speed fluctuation tend to increase during the energization angle modulation, the apparent inertia of the motor increases, and this does not pose a practical problem. FIG. 2 shows the relationship between the rotor position detection signal pattern, the phase conduction signal pattern, the switching pattern, and the pulse width modulation duty ratio and the average output voltage in the embodiment of the present invention at the time of pulse width modulation. FIG. 3 corresponds to energization angle modulation. As apparent from the above description, the brushless motor control device of the present invention switches between acceleration / deceleration operation by pulse width modulation and acceleration / deceleration operation by energization angle modulation in accordance with the number of revolutions. In low-speed operation, pulse pulsation modulation is used to suppress torque pulsation and rotation speed fluctuations. It becomes possible. As a result, a high-efficiency brushless motor control device with low vibration and low noise can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing a control device of a brushless motor of the present invention. FIG. 2 (a) is a diagram showing a rotor position detection signal, a phase energizing signal and a switching pattern. 3A shows a rotor position detection signal, a phase energization signal, and a switching pattern. FIG. 3B shows a waveform pattern and a relation between a duty ratio and an average output voltage. FIG. 4 is a diagram showing a relationship between an angle and an average output voltage. FIG. 4 is a circuit diagram showing a control device using pulse width modulation of a conventional brushless motor. FIG. 5 is a circuit diagram showing a control circuit using current angle modulation of a conventional brushless motor. DESCRIPTION OF SYMBOLS 1 power supply 2 inverter 3 motor 4 position detection circuit 5 phase conduction signal generation circuit 6 pulse width modulation waveform generation circuit 7 conduction angle modulation generation circuit 8 modulation waveform Switching circuit 9 Switching pattern generation circuit 10 Drive circuit

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Katsutoshi Fujita             Matsushita Electric, 1006 Kadoma, Kazuma, Osaka             Sangyo Co., Ltd. F term (reference) 5H560 BB04 BB12 DA00 EB01 EB07                       EC02 SS01 UA06 XA12

Claims (1)

Claims 1. A brushless motor, an inverter for driving the brushless motor, a position detection circuit for detecting a rotation position of a rotor of the brushless motor, and a signal from the position detection circuit. A phase energization signal generation circuit that generates an energization signal for energizing the phase of the brushless motor,
A pulse width modulation waveform generation circuit that generates a pulse width modulation signal from a command voltage; a conduction angle modulation generation circuit that generates a conduction angle modulation signal from a command voltage and a signal of the position detection circuit; Calculate the speed of the brushless motor, the signal of the pulse width modulation waveform generation circuit at low speed operation, the modulation waveform switching circuit to select the signal of the energization angle modulation circuit at high speed operation, the signal of the phase energization signal generation circuit A control device for a brushless motor, comprising: a switching pattern generation circuit that generates a switching pattern of the inverter from a signal of the modulation waveform switching circuit; and a drive circuit that drives a switching element of the inverter.