Novel high voltage capacitor charger for pulsed power modulator

This paper describes a novel 10 kW (10 kV, 1 A) high voltage capacitor charger which has the combined advantage both series loaded resonant inverter and ZVS full-bridge PWM inverter. Series loaded resonant inverter has a wide ZV or ZC switching range regardless of load condition. However it can generate audible noise at light load condition and requires careful filter design because it should be controlled by variable frequency. On the other hand, ZVS full-bridge PWM inverter can be controlled by phase delay of each switching signal with fixed switching frequency, but when it is working at light load condition, efficiency will be decrease because of loosing soft switching condition. The proposed charger has the same structure like series resonant inverter, and controlled at fixed frequency by way of phase shifted PWM. The operational principle of proposed charger and soft switching mechanism is analyzed. The developed charger is verified to have higher efficiency at light load condition and higher power density by way of simulation and experiments. Developed charger and 10 kV IGBT stack based solid state pulsed power modulator was combined and tested with various load conditions. The experimental results verified that the proposed charger can be used effectively for high voltage pulsed power modulator which requires the various kinds of load condition with respect to the applications.