Analysis and design of a high-power electronic load controller for the fuel cell stack testing

Fuel cell(FC) stack is the power source of fuel cell electric vehicles. Its output current and power usually need to be controlled during testing. Electronic load controller(ELC) has often been introduced in FC testing system to control the DC bus. The desired characteristics of such loads include high power, high reliability, high speed of dynamic response and low cost. In this paper, a high performance ELC for FC stack testing was designed according to the test requirement of FC stack´s output characteristics. To ensure continuous input current, the main circuit employed a dual-parallel buck with input LC filters. To suppress the resonance caused by input filters, the transfer function of input current to the duty cycle was obtained by using averaged model. Then the closed-loop control for variable-current mode was achieved. Based on FC stack´s polarization curve, variable-power mode was also achieved, and the function of under-voltage protection was realized. This ELC had been successfully applied in 60kW FC stack testing system, and achieved good accuracy and dynamic characteristics.