Flying-Capacitor Voltage-Balancing Control in Five-Level Active Neutral-Point-Clamped (A-NPC) Converters Using Phase-Disposition PWM

A new control technique for five-level active neutral-point-clamped (A-NPC) inverters is proposed in this paper. The introduced method is based on a set of simple and effortless logic-variables and logic-equations. It actively balances the voltage of the flying-capacitor (FC) at its requisite value, and controls the 5-level A-NPC converter's synthesized voltage according to phase-disposition pulse-width-modulation (PD-PWM) strategy. These logic-variables and equations are derived using the instantaneous measurements of output current and FC's voltage. The regulation of the FC's voltage at its reference operating level and generating the commanded voltage-levels of PD-PWM modulator at output with the less computational requirements are the control targets. The logic-equations and the proposed active balancing technique are validated using the experimental results which are obtained from the prototype of a five-level A-NPC inverter.