FPGA-Based Digital Control Implementation of Unbalance Compensation in Three-phase Three-wire Stand-alone Inverters

This paper presents an FPGA-controlled three-phase inverter programmed for unbalance compensation in the output voltage of the three-phase inverter. The inverter output voltage becomes unbalanced because of the unbalanced load currents drawn by the unbalanced lads of the inverter. The unbalance compensation method mainly uses fundamental harmonic observers, which are designed to decompose a highly distorted voltage and current signal. These observers are embedded into the FPGA. FPGA is used along with other PWM-type controllers and input-output interfaces. The three-phase inverter fundamental output voltage is regulated by using a feedback control system, and a decoupled channel control mechanism has been employed to perform unbalance compensation. Two Cyclone FPGA chip implements the various signal processing steps in the closed loop inverter control methods.