A strong robust DC-DC converter of all-digital high-order sliding mode control for fuel cell power applications

In the fuel cell power applications, the output voltage and load power are variable which highly depends on the operating conditions. Thus, DC/DC power converters are usually utilized to obtain a constant voltage to match the subsequent power bus. Due to the non-linear characteristics of the fuel cell and load profiles, a stronger robustness design of power converters is required. In order to resolve the above issues, this paper designs a strong robust isolated flyback DC/DC converter for the fuel cell power applications. An all-digital controller based on high-order sliding mode (HSM) control is developed. The super-twisting algorithm of HSM is applied with a digital signal processor (DSP) TMS320F28035 that is used as the control chip. In the experiments, the designed digital HSM controller can achieve a fast convergence with a settling time of less than 0.1 ms and an overshoot of less than 0.1%. A typical incremental PI controller is also designed as the benchmark control method. The effectiveness of the proposed digital HSM controller is demonstrated through several different experiments conducted under large disturbances of load and input voltage.