PWAM control of bidirectional LLC resonant converter

This paper proposes an improved bidirectional LLC resonant converter with pulse width and amplitude modulation (PWAM) control method. With the proposed PWAM control method, the converter can be operated with a much wider voltage range at a fixed switching frequency, which can be equal to the resonant frequency. So all the MOFETs can achieve zero voltage switching and MOSFETs in the secondary side can achieve zero current switching. In this way the proposed topology can achieve very high conversion efficiency with no matter heavy load or light load. The proposed bidirectional topology will be popular in the applications of batteries or super-capacitors in energy storage systems and electric vehicles, for the advantage of isolation, high voltage ratio, wide voltage range and high efficiency.