When HERIC(High Efficient and Reliable Inverter Concept) inverter operates at the non-unit power factor, there are larger turn-off voltage spikes on freewheeling switches than operating at the unit power factor, which increases switching loss, devices voltage stress, and electromagnetic interference. Moreover, the turn-off voltage spikes are much larger in some high-frequency applications, owing to the larger di/dt. This paper analyzes the turn-off voltage spikes of freewheeling switches when the HERIC inverter operates at the non-unit power factor. On this basis, a passive clamping circuit is proposed, which is simple, cheap, and lossless, and its principle is analyzed. Finally, a 10kW prototype was used to verify the proposed circuit.

HERIC(High Efficient and Reliable Inverter Concept),Passive and lossless clamp absorption circuit,Non-unity power factor,Photovoltaic-energy storage system