The effect of space vector modulation on 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 trade-off between harmonic performance and switching frequency. However the nature of the techniques used to balance the capacitor voltages in this modulation strategy can increase capacitor voltage ripple. This paper compares the key performance indicators in differing space vector modulation techniques including capacitor voltage ripple, total harmonic distortion and switching losses. It is shown that while one of these techniques significantly improves the trade-off between harmonic performance and switching loss it can also significantly reduce the capacitor lifetime due to the form of the resultant ripple currents.