Design aspects of synchronous PWM rectifier-inverter systems under unbalanced input voltage conditions

Abstract

A complete analysis of a synchronous front-end PWM rectifier-inverter system under unbalanced input voltage conditions is presented. The analysis includes the harmonic assessment of input/output current and voltage waveforms. It is shown both theoretically and experimentally that input voltage unbalance generates uncharacteristic low-frequency harmonic components in the input and output currents. Special emphasis is given to the generation of a DC component in the inverter output voltage in the case in which the output frequency is twice the input frequency. System design curves for different degrees of unbalance for all major system components are reported. Key predicted results are confirmed experimentally.