A high-power switch-mode DC power supply for dynamic loads

High-voltage DC power supplies are often required to operate with highly dynamic loads, such as arcs. A switch-mode DC power supply can offer significant advantages over conventional thyristor-based DC power supplies under such conditions. It can quickly turn off the supply to extinguish the arc, and it can quickly recover after the arc. It has a relatively small output filter capacitance, which results in small stored energy available to the arc. A 400 kW, 50 kV switch-mode DC power supply for an electron-beam gun that exploits these advantages was designed and tested. It uses four 100 kW, current-source-type DC-DC converters with inputs in parallel and outputs in series. The DC-DC converters operate at 20 kHz in the voltage regulator part and 10 kHz in the inverter, transformer, and output rectifier part of the circuit. Insulated gate bipolar transistors (IGBTs) are used as the power switches. Special techniques are used to protect the power supply and load against arcs and hard shorts. The power supply has an efficiency of 93%, an output voltage ripple of 1%, and fast dynamic response. In addition, it is nearly one-third the size of conventional power supplies