Fixed frequency integral sliding-mode current-controlled MPPT boost converter for two-stage PV generation system

摘要： In two-stage grid-integrated photovoltaic (PV) system, usually a DC–DC converter is employed between the PV modules and the inverter. The dynamic interactions between the DC–DC converter, inverter, and the maximum power point tracking (MPPT) controller may affect the system performances. This study gives an integral procedure to design a stable sliding-mode controller (SMC) based on fixed frequency equivalent control approach to improve the transient response of PV system and to track the reference voltage supplied by the voltage-oriented MPPT controller in the presence of environmental and load perturbations and converter output sinusoidal perturbations imposed by the second harmonic of the grid frequency. The controller consists of fast current tracking inner current loop based on SMC law whose sliding surface is defined by the input capacitor and inductor current and outer PI controller maintains required PV voltage regulation. The superiority of the controller is validated at different operating conditions through PSIM software and its performance is compared with variable frequency hysteresis-based SMC. To check the static and transient performances of the system, various experiments are conducted. The results obtained show very fast transient response in settling time and alleviation of chattering magnitude at various operating conditions.