Nonlinear single-loop control of the parallel converters for a fuel cell power source used in DC grid applications

This paper presents an innovative control law for a multiphase interleaved converter in the distribution of power supply in fuel cell (FC) generators. Traditionally, to control the DC output power, voltage, or current in a converter, a linear multiple-loop feedback control technique is used. The nonlinear multiple-loop feedback control approach offers several techniques that help to improve the system response. In this paper, an alternative nonlinear single-loop feedback control scheme is proposed. This scheme is based on the differential flatness concept, which provides a solution to achieve the preferred response using a less sophisticated algorithm. To validate the proposed technique, a prototype of a FC power converter (a 600-W two-phase interleaved boost DC-DC converter) was constructed in the laboratory, and the control algorithm was implemented to control the prototype using a dSPACE 1104 controller card. The control scheme exhibited excellent experimental results for use with a 1.2-kW Nexa Ballard polymer electrolyte membrane fuel cell (PEMFC) regarding the steady state and dynamic responses as well as the control robustness.