METHOD AND APPARATUS FOR SYNCHRONIZING PWM SINUSOIDAL DRIVE TO DC MOTOR

摘要

PURPOSE: A method and an apparatus for synchronizing PWM sinusoidal drive to DC motor are provided to synchronize the drive voltages to a DC permanent magnetic motor when the motor is driven with pulse width modulated(PWM) waveforms. CONSTITUTION: A drive circuit for a motor includes a circuit to detect a phase difference between a drive voltage to be applied to a terminal of the motor and the BEMF(back electromagnetic) from the motor. The drive circuit includes a high impedance state to apply discontinuities to the motor. The drive circuit responses to the phase difference to maintain a predetermined phase difference between the drive voltage and the BEMF of the motor. The discontinuities are 6 per electrical cycle.