DC-Side Soft-Switching Inverter with Modified Space-Vector Modulation Scheme

Abstract

Three-phase soft-switching inverters are promising in order to reduce the losses in the switching devices and to reduce the electromagnetic interference produced by severe di/dt and dv/dt, which enables the operation of the inverter at higher switching frequency. This work proposes a DC-side three-phase zero-voltage soft-switching inverter topology that can be sub-categorized under actively clamped resonant dc-link topologies. Moreover, a modified space-vector modulation scheme is proposed, such that all the devices operate under zero-voltage switching condition. Compared to other similar dc-link soft-switching topologies, the proposed topology does not require feedback from the inverter output currents to achieve soft-switching operation. Unlike conventional space-vector modulation techniques, the proposed modified space-vector modulation does not require to turn-on the top and/or the bottom three switches of the two-level inverter at the same time to implement the zero vectors, which allows a reduction of the effective commutating time of the two-level inverter switches by one-third, during a grid voltage cycle. The auxiliary capacitor is only charged to a fraction of the dc bus voltage. Simulation and experimental results on a 10-kW and 100-kHz switching frequency lab-scale prototype are presented to demonstrate the validity and effectiveness of the proposed zero-voltage switching topology and modulation scheme on reducing the switching losses and electromagnetic interference.