Voltage Control of Autonomous Three-Phase Four-Leg VSI Based on Scalar PR Controllers

A control of a three-phase four-leg autonomous voltage source inverter (VSI) based on scalar PR-controllers with as part of an autonomous power supply system (APS) is presented. The proposed method independently controls each phase load voltage in the coordinate system ABC. The control system of the VSI consists of an outer control loop for controlling the load voltages and an inner control loop for controlling the output current of the VSI. To analyze the stability of the system and design the PR regulators, the root locus and the Bode diagram are used. The control signals applied for the VSI switches are provided by Scalar PWM. Studies of operating modes of APS are carried out using MATLAB/SIMULINK. The proposed method shows good tracking of the reference output voltage in the static and dynamic modes of APS.