Non-uniform capacitor voltage ripple in a cascaded H-bridge StatCom

Employing space vector modulation in a multi-level H-bridge StatCom (H-StatCom) can provide an excellent tradeoff between harmonic performance and switching frequency. However the nature of the techniques used to balance the capacitor voltages in this control strategy means that capacitor voltage ripple is increased. This can have detrimental effects on the current tracking performance. This paper both compares the capacitor voltage ripple in differing space vector modulation techniques and develops a compensation scheme to minimise the effect of ripple on the current tracking performance. Simulation results are presented that confirm the correct operation of the compensation scheme.