CAPACITOR TRAPPED CURRENT FED SOFT SWITCHING PUSH PULL DC-DC CONVERTER FOR RENEWABLE ENERGY CONVERSION

Abstract

The design and analysis of Capacitor Trapped Current fed Soft Switching Push Pull DC DC Converters for renewable energy conversion applications is presented in this thesis work. The proposed two converters are designed to address the challenges of efficient power conversion and integration of renewable energy sources by combining the inherit advantages of current fed push pull converter with ZCS technique to achieve high efficiency, lower conduction losses of the primary switches , low EMI noise , high reliability and smaller size. The nominal 48V bus voltage is step up to 380V utilizing the proposed converters operating at 100kHz switching frequency and 500W power level. The first architecture uses dual trapped capacitor structure on the primary side to achieve ZCS and the second architecture uses single capacitor trapped structure to achieve ZCS owing to the resonance between the primary side trapped capacitors and leakage inductance of the HF transformer as a result the first architecture is able to achieve voltage at transformer’s primary having quasi square waveform and sinusoidal waveform in case of secondary architecture. In both proposed architectures natural clamping is achieved which results in mitigating the need of auxiliary clamping or snnuber circuit to reduce voltage stress on power switches as a result number of requirement of power switches also reduces. The voltage spike across the power devices are suppressed effectively enabling the selection of low voltage, low cost power devices. Since all the switches are ground referred in both proposed converters, non-isolated driver with single power supply can be employed. SiC diodes are used in the output rectifier side to minimize to reverse recovery problem in both the proposed architectures.