Modelling and Control of Unipolar Pulse Width Modulated Voltage Source Inverter

This paper presents a study on the modeling and control of a Unipolar Pulse Width Modulated (PWM) Voltage Source Inverter (VSI). Specifically focusing on current control in a unipolar PWM single-phase inverter, the paper rigorously derives and analyzes the transfer function for current control. A Proportional-Integral (PI) controller is designed to achieve desired performance metrics. Simulation and experimental results validate the efficacy of the proposed controller, demonstrating its robustness in tracking reference current under varying circuit parameters. Additionally, the observed behavior aligns with theoretical predictions, particularly concerning the phase difference between reference and actual currents at higher modulating frequencies. However, analysis reveals a consistent phase displacement in the closed-loop system, suggesting the persistence of some phase difference between input and output signals unless the frequency is zero.