Motor controller and steering device

• US 20060113937A1
• Filed: 11/08/2005
• Published: 06/01/2006
• Est. Priority Date: 11/30/2004
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Kojo, Takahiro, Hidaka, Kenichiro, Miyata, Masahiro, Kawai, Motoshi, Hiramine, Mikihiro, Tsutsui, Toshio
• Granted Patent: US 7,248,016 B2
• Time in Patent Office: Days
• US Class Current: 318/432
• CPC Class Codes: B62D 5/046 Controlling the motor
• CPC Class Codes: H02P 21/05 specially adapted for damping motor oscillations, e.g. for reducing hunting
• CPC Class Codes: H02P 27/08 with pulse width modulation
• CPC Class Codes: H02P 27/085 wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency
• CPC Class Codes: H02P 6/10 Arrangements for controlling torque ripple, e.g. providing reduced torque ripple

Abstract

A motor controller including an inverter including plural switching elements that are subjected to PWM control to generate sine waves of plural phases, a motor including a stator coil supplied with the sine waves thus generated so that rotational magnetic field is generated in the stator coil, and a rotor that is rotationally driven by the action of the rotational magnetic field generated by the stator coil, a storage unit for detecting the sine waves of the respective phases generated in the inverter and storing a correction amount for each phase that is calculated on the basis of the detection result so that the sine waves of the respective phases are coincident with one another and a correcting unit for correcting a PWM signal for carrying out the PWM control on the switching elements on the basis of the correction amount thus calculated.

Claims

1. A motor controller comprising:

an inverter including plural switching elements that are subjected to PWM control to generate sine waves of plural phases;

a motor including a stator coil supplied with the sine waves thus generated so that rotational magnetic field is generated in the stator coil, and a rotor that is rotationally driven by the action of the rotational magnetic field generated by the stator coil;

a storage unit for detecting the sine waves of the respective phases generated in the inverter and storing a correction amount for each phase that is calculated on the basis of the detection result so that the sine waves of the respective phases are coincident with one another; and

a correcting unit for correcting a PWM signal for carrying out the PWM control on the switching elements on the basis of the correction amount thus calculated.

2. The motor controller according to claim 1, wherein the correction amount is calculated so that the sine wave of each phase is coincident with a reference sine wave different from the sine waves of the respective phases.

3. The motor controller according to claim 1, wherein the correction amount is calculated so that one of the sine waves of the respective phases is set as a reference sine wave and the sine waves of the other phases are coincident with the reference sine wave.

4. The motor controller according to claim 2, wherein the correction amount contains an offset value for offsetting a level at which the polarity of the sine wave of each phase is changed so that the absolute values of the peak values at positive and negative polarity sides of the sine wave from the level concerned are substantially equal to each other, and a gain that is set so that the peak values at the positive and negative polarity sides of the sine wave are coincident with the respective peak values of the reference sine wave.

5. The motor controller according to claim 1, wherein the correction amount is calculated on the basis of the sine wave under the state that the rotor of the motor is locked.

6. The motor controller according to claim 5, wherein the correction amount is calculated only once before shipping and stored in the storage unit, and the correcting unit corrects the PWM signal on the basis of the correction amount at all times.

7. The motor controller according to claim 5, further comprising a correction amount calculating unit for calculating the correction amount, wherein the correction amount is calculated by the correction amount calculating unit and stored in the storage unit every time the motor is started, and the correcting unit corrects the PWM signal on the basis of the correction amount.

8. The motor controller according to claim 4, wherein the correcting unit carries out gain-based gain correction on the PWM signal to calculate a gain-corrected PWM signal, and when the polarity of the gain-corrected PWM signal is different from the polarity of the PWM signal before the gain correction, the correcting unit carries out clamp processing for nullifying the value of a portion at which the polarity of the gain-corrected PWM signal is different, thereby calculating a clamp-processed PWM signal.

9. The motor controller according to claim 8, wherein after the clamp-processed PWM signal is calculated, the correcting unit carries out offset correction based on an offset value to calculate an offset-corrected PWM signal.

10. The motor controller according to claim 1, wherein the sine wave is a voltage value output to the terminal of each phase.

11. The motor controller according to claim 1, wherein the sine wave is a current value output to each phase. An electrical quantity output from the inverter to each phase is taken out as a current value.

14. The motor controller of claim 1, wherein the motor controller is implemented in a steering device for driving a motor on the basis of a steering state detected by a steering state detecting unit, and actuating a transmission ratio varying mechanism for varying the transmission ratio between a steering angle of a steering wheel and a turning angle of a steered wheel, or an auxiliary mechanism for assisting the steering force of the steering wheel.

12. A motor controller comprising:

an inverter including plural switching elements that are subjected to PWM control to generate sine waves of plural phases; and

a motor including a stator coil supplied with the sine waves thus generated so that rotational magnetic field is generated in the stator coil, and a rotor that is rotationally driven by the action of the rotational magnetic field generated by the stator coil, wherein the switching elements are grouped in accordance with a predetermined range of electrical characteristic values, and the inverter is constructed by using the switching elements belonging to the same group.

13. The motor controller according to claim 12, wherein the electrical characteristic value contains a threshold voltage of each switching element, the resistance value of a resistor connected to a control terminal (gate terminal in MOSFET) of each switching element, the capacitance of a capacitor or parasitic capacitance corresponding to the internal capacitance of each switching element.

15. A motor controller comprising:

a correcting unit for correcting basic PWM signals generated by a dead time compensator to thereby prevent dispersion of waveforms of the motor current (Iu, Iv, Iw) of the respective phases and resultant torque variation n the motor, wherein the correcting unit comprises a gain corrector for subjecting the basic PWM signals to gain correction based on a gain value stored in a correction amount storage unit and subjecting the gain corrected signal to clamp processing; and

an offset corrector for subjecting the clamp processed PWM signal to an offset correction based upon an offset value stored in the correction amount storage unit.

16. The motor controller of claim 15, wherein the offset value offsets a level containing a zero cross point of voltage waveforms of the PWM signals being measured so that an absolute value from the zero cross point to a peak value at positive polarity side is equal to an absolute value the zero cross point to a peak value at the negative polarity side, wherein the gain value is a measure of deviation between peak value of the positive polarity side of the voltage waveform after the offset and peak value at positive polarity side of a reference voltage waveform, or the deviation between peak value at the negative polarity side of the voltage waveform after the offset and peak value at negative polarity side of the reference voltage waveform.