Three-level H-Bridge Chopper for High Ceiling Voltage VSC Excitation System

A three-level H-bridge chopper using neutral point clamped technology is proposed for high ceiling voltage VSC excitation system to suppress overvoltage stress and shaft voltage. Highlighting with neutral point voltage balance control, the switching states of the three-level H-bridge chopper is specially designed and implemented for excitation voltage control. A prototype is fabricated and the laboratory test with small generator is carried out for verification.