A Novel DC Voltage Detection Technique in the CHB Inverter-Based STATCOM

A novel dc voltage detection technique, referred to as single multiple-voltage (SMV) detector, is developed to obtain dc capacitor voltages in the cascaded H-bridge (CHB) multilevel inverter-based static synchronous compensator (STATCOM). Based on the proposed SMV algorithm, the number of voltage sensors is substantially reduced. Only three voltage sensors are required to obtain dc capacitor voltages from the inverter output voltage. The paper also presents a new dc voltage balance control method that combines the phase shifting technique and sinusoidal pulsewidth modulation (SPWM) strategy for the control of H-bridge dc capacitor voltages. The performance of CHB inverter- based STATCOM system, the accuracy of the developed SMV detector and the effectiveness of the proposed dc voltage balance control are verified by simulations in Simulink environment and experiments based on the dSPACE prototype system.