Enhanced pulsewidth modulation strategy of six-switch converter for single phase online uninterruptible power supply

This paper investigates the novel modulation method of six-switch back-to-back converter for the application of an online uninterruptible power supply. With an additional current direction judgment logic and related modulation adjustment, the total modulation index can be increased and consequently the overall losses and the voltage stress across semiconductors will decrease significantly, being much different from other modulation methods of the six-switch converter. Matlab simulation and experimental prototype are constructed to verify the performance of the proposed modulation method.