The torque ripple caused by diode freewheeling of the inactive phase during non-commutation state of PM brushless DC motor(BLDCM)when using the PWM_ON type of pulse width modulation was analyzed.

The design method for hybrid waveforms utilizing ran-dom poly-cell code pulse position modulation (PPM) and pulse-to-pulse binary sequences phase modulation (PM) is introduced in this paper.

In frequently used methods, sine wave is used as carrier with amplitude modulation (am), frequency modulation (FM) and phase modulation (PM) implied.