A zero-voltage DC bus commutated high-frequency high-power PWM 3-phase VSI

An effective DC bus zero voltage switching (ZVS) turn-off method for high-frequency high-power pulse-width-modulation (PWM) voltage source inverters (VSIs) is presented. This method utilizes an innovative simple DC bus commutating subcircuit (consisting of only a DC bus interrupt switch and a capacitor connected across the DC bus) and a compatible PWM scheme. To minimize effective inverter switching frequency, the subcircuit provides ZVS only when needed and as dictated by the PWM scheme. Thus, switching losses and switch stresses are minimized, enabling the PWM to operate at high switching frequencies. Moreover, the DC bus commutation switch can be utilized to isolate the inverter under abnormal operation conditions. Complete circuit analysis, design guidelines, and a design example are also presented. Predicted results are verified by simulation.<
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