Modal Computation and Analysis Based on Phase Sequence of LLC Resonant DC-DC Converter

摘要

LLC resonant DC-DC converter has wide working range, good voltage gains, and soft switching performance. So it is widely used in power transformation systems of new energy equipment such as UPS, electric vehicle, and photovoltaics (PV). The conduction loss in the main circuit constitutes the main loss occurred in the LLC resonant converter. It may greatly improve the power conversion efficiency of the converter by reducing the conduction loss. To solve the above problems, a method is proposed to calculate and design the parameters of the resonant element in this paper. This method abandons the traditional time sequence mathematical model, and, in order to reduce the effective value of the main loop current of resonant converter, the phase sequence modal analysis is applied. With ZVS as the constraint condition, the design parameters of resonance element that can minimize the conduction loss can be obtained. In the final part, an experimental prototype (300W) is designed and the effectiveness of the mentioned method is verified.