Abstract：In order to reduce the common-mode(CM) voltage and CM current caused by the asymmetry of the circuit in the three-phase three-leg inverter, this paper proposes a novel sinusoidal pulse width modulation (SPWM) control strategy based on three-phase four-leg structure. This strategy, in which the SPWM jump-edge is delayed when zero-state appears, is an improved method on the basis of the SPWM carrier phase-shifting control technology. It can ensure the output balance of four legs in inverter under any conditions, and thus restrains the generation of CM interferences. Compared with the original SPWM carrier phase-shifting control strategy in three-phase four-leg inverter, the jump-edge delay method breaks through the limitation of SPWM modulation index which must be less than 0.666, avoids the extremely low utilization ratio of direct current(DC) voltage, and can be used with arbitrary modulation index. The effectiveness of the control strategy is proved by simulation and experiment results.
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2009, Vol. 24 
