Design of space vector-based hybrid PWM techniques for reduced current ripple

Switching sequence used by conventional space vector PWM (CSVPWM) involves equal division of zero vector time between the two zero states in every subcycle. The sequences employed by bus-clamping PWM involve use of only one zero state in a subcycle. This paper deals with two sequences, which use only one zero state and involve division of active vector time within a subcycle. A novel hybrid PWM technique, employing these two sequences in conjunction with the conventional sequence, is proposed. The proposed PWM technique is designed using the notion of stator flux ripple. A procedure is presented for designing hybrid PWM techniques involving multiple sequences for reduced current ripple. The proposed PWM technique results in reduced current ripple over CSVPWM at higher modulation indices. Experimental results on a 2 hp prototype induction motor drive are presented.