Model predictive control of a cascaded H-bridge multi-level StatCom

A multi-level H-bridge StatCom inherently contains redundancy in the available switching states. This paper develops a Model Predictive Control (MPC) scheme which is able to exploit this redundancy to optimise three competing objectives. The scheme can simultaneously balance the H-bridge capacitor voltages, provide excellent current reference tracking and optimise converter switching losses. A variation in modulation scheme, consisting of a hybrid of traditional MPC and PWM strategies, is also described. Simulation and experimental results are presented that confirm the correct operation of the control and modulation strategies. Comparison with traditional control and modulation schemes is provided in terms of the key performance indicators associated with multi-level H-bridge StatComs.