Variable sampling quasi multirate deadbeat control method for PWM Inverter in low carrier frequency

A new approach for real time digital feedback control of single phase and three phase PWM inverter is proposed, in which a quasi multirate deadbeat control combined with variable sampling method using FPGA based hardware controller. It was reported that the deadbeat control method with FPGA based hardware controller had the very good transient response for various loads, but these reports were mainly focused on a few KW class PWM inverter system, so the high carrier frequency were adopted for evaluation. But in MW class PWM inverter system, the carrier frequency is limited up to 2 kHz range, because of the performance of the switching devices and the trade off against the efficiency of the inverter. In this condition, the controllability of the PWM inverter is not so much expected. In the proposed method, to ensure the tracking accuracy of the output voltage to the reference voltage, more than two sampled data is used while one carrier interval. The proposed method is applied to single phase system and then expanded to three phase PWM inverter system. The control characteristics of the proposed variable sampling deadbeat control were verified through simulations and experiments.