Advanced single-loop discrete-time control for T-type voltage source inverter with minimum capacitor voltage ripple modulation

Abstract

This research focuses on improving the performance of the voltage source inverter (VSI) which has been widely used in practical applications such as uninterruptible power supply (UPS), photovoltaic (PV) systems in standalone mode. To reduce the total harmonic distortion (THD) of the output voltage without increasing the switching frequency, the T-type three levels inverter with enhanced modulation strategy which minimizes the voltage ripple of the two input capacitors is employed. In addition, a new single-loop fully digital control strategy in which various advanced control techniques such as proportional-integral observer, one-step ahead minimum prediction error and model-based current command generator is also proposed to fulfill the strict requirements of the output voltage. The proposed control strategy is capable of achieving excellent output voltage regulation and high robustness against the parameters variation with low computational cost. Real-time simulations based on hardware in the loop (HIL) platform are conducted to confirm the validity of the method.