Circuit and method for removing increased power supply current spike that occurs during initial turn-on or commutation point in PWM mode spindle motor drive system

摘要

A method and circuit (55) are presented for reducing a current spike (9) created after a commutation of a driving current of a polyphase motor (14). The motor (14) has a plurality of coils (40) that are driven by a commutated dc voltage from a power supply. The circuit (55) includes a circuit that produces a signal (DrvENOccurred) for indicating a commutation of the dc voltage and a circuit for PWM modulating the dc voltage (CLK,74) during at least a portion of a time before a current induced in one of the coils (40) reaches a peak value. A counter (57) determines at least a portion of a time that begins a delayed time after the commutation, and ends when the current reaches the peak value.