High-power pulsewidth controlled current source GTO inverter for high switching frequency

High-power GTO inverters require regenerative snubbers to ensure operation at predefined values of di/dt and du/dt. The use of regenerative snubbers for voltage source inverters is a well established technology. However, the proliferation of high-power PWM current source inverters is impeded by the nonavailability of an appropriate regenerative snubber scheme. The paper proposes a regenerative snubber for current source GTO inverters and reports experimental results of a 1.2 MVA prototype inverter. Energy recovery from the snubbers enables operation at extreme high switching frequency of 1 kHz and reduces the total filter kVA from 70% to 20% of the inverter power.