Simulation analysis of voltage balancing scheme using multicarrier techniques for three phase three-level Flying-Capacitor (FC) front-end converter

Conventional AC-DC converters has drawbacks in terms of poor power factor and higher harmonic distortions because of its non-linear loads. Front end converters have been developed to improve the power quality with unity power factor and lower harmonic distortion. In this paper three-phase three-level Flying-Capacitor (FC) based front end converter using multicarrier sinusoidal pulse width modulation (SPWM) scheme has been proposed. Simulation and comparative analysis of phase shifted (PS) pulse and phase disposition (PD) pulse width modulation at different modulation index has been done and it is found that PS-PWM technique offers lower harmonic distortion compared to PD-PWM multicarrier technique. This paper proposes voltage balancing scheme using PS-PWM technique whereby triangular carrier is modified through closed loop model to control amplitude modulation index such that the capacitor voltage gets balanced. The analysis of voltage balancing scheme has been carried out by MATLAB/Simulink software and it is found that it is able to maintain the capacitor voltage to its desire voltage and also gives unity power factor with lower harmonic distortion.