A Novel Hybrid Fuel Cell Power System

A hybrid fuel cell power system is proposed in this paper. It consists of a fuel cell, an isolated uni-directional converter, a bi-directional converter, an inverter and a battery. A novel uni-directional converter, hybrid full bridge LLC resonant converter, is proposed and acts as a uni-directional converter in the system. It has several advantages such as: ZVS capability from nearly zero to full load; the rectifier diodes sustain only the output voltage, and realize ZCS; the input current ripple and output filter can reduced; and; high efficiency can be achieved over a wide input voltage range. A new three-level bi-directional converter is employed in the system as the core of the energy management control. Compared with the traditional bidirectional converter, it has some advantages as follow: The structure is simple, and easy to control; the voltage stress on the switches is just half of the V_H; the inductor can be reduced significantly, which lead to fast dynamic response. In order to ensure the system operates with high efficiency, energy management is introduced into the system. The energy management method is proposed in the paper. Experimental results are shown to verify the theoretical analysis