Comparative Study Of Control Methods for Power Quality Improvement of Autonomous 4-Leg Inverters

Comparative study of the methods for controlling a stand-alone voltage source inverter with a fourth leg (4-leg VSI) based on scalar pulse width modulation (PWM) and Finite control set model predictive control (FCS-MPC) as part of an autonomous power supply system are presented. The main purpose is to control 4-Leg VSI to provide balanced load voltage with lower total harmonic distortion. The discrete-time model of the autonomous 4-Leg VSI with output LC filter is pointed out for predicting the output voltage at a varying load. The PID controller is employed to provide the control reference signal for the PWM. The performances of the two control methods in tracking the load voltage under steady state and transient conditions are analyzed.