Improvement for very high efficiency chopper circuit SAZZ

The paper describes a study aiming at reaching a very high 99 % efficiency in DC-DC chopper for electric vehicle (EV) application by improvements of conventional SAZZ topology. Optimisation of the operating frequency and the use multiple parallel SiC diodes were the main improvements of SAZZ chopper that were studied. These led to obtaining the efficiency of 98.96 % in an 8 kW experimental setup. New, 30 kW fully bi-directional DC-DC converter based on SAZZ topology is introduced in this paper as well. The main goal of this new design was to reach efficiency close to 99 % by improving the performance of SAZZ topology through small modifications as discussed in the paper. The proposed modifications are simple, but result in substantial improvements with high conversion efficiency over 98 % over whole practical region in the power range required by EV application.

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