A Pulse Step Modulator High-Voltage Power Supply for Auxiliary Heating System on the HL-2A Tokamak

To supply the cathode voltage for the two gyrotrons (140 GHz/1 MW/3 s) of the electron cyclotron resonant heating system on HL-2A, a high-voltage power supply (HVPS) based on pulse step modulator (PSM) with rated output of 80 kV/200 A has been built. Because the storing energy of the PSM HVPS is much lower than traditional HVPS, it is beneficial to load protection. In the PSM HVPS, there are eight dry-type multiwinding transformers; each transformer has 14 secondary windings. The main insulation of the multiwinding transformer reaches to 150 kV. There are 112 switch power supplies in the PSM HVPS; the output voltage can be regulated from 0 to 80 kV by modulating their delay time and pulsewidths. To realize two gyrotrons parallel operating and respective quick protection for the loads, two solid-state high voltage modulators (SSHVM) based on insulated gate bipolar transistor are applied in the power supply. The over-current and over-voltage protection are executed by turning off the PSM HVPS and the SSHVM. The protection time is <;10 μs. A fully digital controller based on digital signal processor and field programmable gate arrays has been developed to ensure the stability of the output voltage of the PSM HVPS. The design circuit and elements are described, and the test results of the PSM HVPS are given in this paper.