High frequency transformer based improved gamma ZSI with lossless snubber

Abstract

© 2018 IEEE. This paper presents an improved single phase high frequency isolated gamma Z-source inverter (ZSI) with clamped diode. It consists of a high frequency transformer between the inverter bridge and load. A lossless snubber diode is employed to provide voltage clamping across the DC-link voltage to overcome the voltage overshoots caused by the leakage and stray inductances of the magnetic components. The proposed concept retains all the existing benefits of ZSIs which are buck/boost function, single stage power conversion, immunity from dead and overlap times, and increased reliability. Together with high frequency transformer makes it a good candidate for solar PV applications. High frequency isolation has many benefits in terms of protection and safety. In addition to these it can provide immunity from de-circulating current without the need for external bulky line transformer. The proposed topology can increase gain with maximum value of modulation index which is currently not possible with any other impedance source topology. The described benefits and features of the proposed topology are verified through comprehensive theoretical analysis, simulations and prototype based hardware experiments.