초록 ▼

A PWM controlled multiphase DC motor apparatus has a multiphase DC motor, a current sensor, and a PWM controller. The DC motor has multiple windings which turn on and off during commutation at a commutation frequency. The current sensor is coupled to sense power supply current flowing in all winding

A PWM controlled multiphase DC motor apparatus has a multiphase DC motor, a current sensor, and a PWM controller. The DC motor has multiple windings which turn on and off during commutation at a commutation frequency. The current sensor is coupled to sense power supply current flowing in all windings of the DC motor. The PWM controller is coupled to control the DC motor using a PWM signal at selected PWM frequency with variable duty cycle. Using the feedback from the current sensor, the PWM controller maintains approximately constant torque in the DC motor by adjusting the duty cycle of the PWM signal. The PWM controller includes a soft switching circuit which manipulates a voltage used to generate the controlling PWM signal in a manner which causes linear stewing of currents in the windings during commutation. The linear current stewing occurs at a slew rate that is slow relative to the PWM frequency to thereby reduce torque ripple during commutation. The combined features of continuous PWM duty cycle control and linear current slewing during commutation significantly reduces torque ripple at the fundamental commutation frequency, as well as at the first few harmonics. A method for PWM control of a multiphase DC motor is also described.

대표청구항 ▼

[ What is claimed is:] [1.] An apparatus comprising:a multiphase DC motor having multiple windings which turn on and off during commutation at a commutation frequency, the windings turning on and off at different times from one another;a current sensor coupled to sense power supply current flowing i

[ What is claimed is:] [1.] An apparatus comprising:a multiphase DC motor having multiple windings which turn on and off during commutation at a commutation frequency, the windings turning on and off at different times from one another;a current sensor coupled to sense power supply current flowing in all windings of the DC motor;a PWM controller coupled to control the DC motor based upon feedback from the current sensor, the PWM controller generating a PWM signal at a selected PWM frequency with variable duty cycle to control the DC motor, the PWM controller using the feedback from the current sensor to maintain approximately constant instantaneous torque in the DC motor during commutation by adjusting the duty cycle of the PWM signal; andthe PWM controller comprising first and second duty cycle controllers, the first duty cycle controller being used to adjust the duty cycle of the PWM signal for a winding being turned on during commutation and the second duty cycle controller being used to adjust the duty cycle of the PWM signal for a winding being turned off during the same commutation, the first and second duty cycle controllers reversing their function in a subsequent commutation whereby the first duty cycle controller is used to adjust the duty cycle for a winding being turned off and the second duty cycle controller is used to adjust the duty cycle for a winding being turned on.