Analysis and Design of a New Current-Source Output Load Resonant Converter With High Capability in Line and Load Regulation

In this paper a fourth-order Passive Resonant Tank (PRT) is introduced using a topological modification in LLC tank for current-source output applications of Load Resonant Converters (LRCs). The design procedure is based on the output current/input voltage ratio decoupling from the load coefficient. Therefore, output current can be independent of load variation topologically. In this condition, new criterions are applied on the operational frequency and PRT components ratio. Moreover, kVA/kW ratio of the LRC is considered as a comparing index, to optimize the converter size as well as reduction of voltage/current stresses on the PRT components. To reduce the discrete components number, transformer parasitic inductances and bridge capacitors are used as the PRT components. Also, a simple and accurate PWM-based Quasi-Proportional Controller (QPC) is designed to maintain the output current constant against input voltage variations. Minimum reactive power, low circulating and turn-off current, and ZVS of the inverter switches in a wide loads range are obtained as the advantages of the designed LLCC-LRC. Moreover, sinusoidal shape of the PRT input current and minimum switching losses on the rectifier are maintained. Finally, an experimental prototype with 3.5A output current and 93.9% efficiency is presented for results verification.