This paper investigates certain novel switching sequences involving division of active vector time for space vectorbased pulsewidth modulation (PWM) generation for a voltage source inverter. This paper proposes two new sequences, and identifies all possible sequences, which result in the same average switching frequency as conventional space vector PWM (CSVPWM) at a given sampling frequency. This paper brings out a method for designing hybrid PWM techniques involving multiple sequences to reduce line current ripple. The three proposed hybrid PWM techniques (three-zone PWM, five-zone PWM and sevenzone PWM) employ three, five and seven different sequences, respectively, in every sector. Each sequence is employed in a spatial region within the sector where it results in the lowest rms current ripple over the given sampling period. The proposed techniques lead to a significant reduction in THD over CSVPWM at high line voltages. The five-zone technique results in the lowest THD among real-time techniques with uniform sampling, while the seven-zone technique is the best among real-time techniques with twin sampling rates. The superior harmonic performance of the proposed techniques over CSVPWM and existing bus-clamping PWM techniques is established theoretically as well as experimentally.

No abstract

No abstract

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 2hp prototype induction motor drive are presented.