A Minimum-Energy-Based Capacitor Voltage Balancing Control Strategy For MPC Conversion Systems

In ACIDCIAC power conversion, the connection of a Multi Point Clamped (MPC) rectifier with an MPC inverter simplifies the balancing of the voltages on the series-connected DC link capacitors as well as giving input power-factor correction capability. This is only true provided that an alternative balancing PWM control strategy is adopted instead of the standard PWM one. A control strategy is proposed which is based on the development of an energy function which may be minimized in real time by exploiting the existing redundancies in power-converter switching states. This strategy may be easily implemented in a DSP controller and is usable with any number of voltage levels and inputloutput phases. A validation has been performed by simulating a 5-levels 3-phase MPC system and significant waveforms are presented.