An analysis and design of a force commutated three-phase PWM AC controller with input unbalance correction capability

The analysis and design of a direct nine-switch three-phase pulse-width modulated AC controller, capable of correcting input unbalance, are presented. A novel voltage unbalance correction method using positive and negative sequence voltage components is shown to have superior performance features. These features include output voltage balancing capability, full semiconductor utilization, simple implementation, and the direct control of the three output balanced fundamental voltage components. Selected examples are implemented by simulation and experimental prototyping to illustrate the validity and significance of the proposed unbalance correction control method