An Extremely Low Ripple High-Voltage DC Power Supply System for Depressed Collector Traveling-Wave Tubes

This article investigates the impact of isolating transformer stray capacitances on the output voltage ripple of the high-voltage dc power supply system used in depressed collector traveling-wave tubes (TWTs). It is shown that the common-mode (CM) capacitive current from the isolating transformer of the TWT’s depressed collector power supply passes through the output of the TWT’s cathode power supply. Therefore, an additional ripple is generated at the output of the cathode power supply. In high-voltage applications, adding filters to reduce ripple conflicts with the protection considerations of the load and the power supply. This study focuses on reducing this extra voltage ripple without adding new filters. An analysis is presented to demonstrate the relationship between the voltage ripple of the TWT’s cathode power supply and the stray capacitances of the isolating transformer. A transformer winding structure is then proposed to eliminate the CM capacitive current of the collector power supply. Simulation and experimental results show that using the proposed transformer winding structure leads to a 90% voltage ripple amplitude reduction at the cathode power supply output.