A High-Voltage Pulse Modulator Composed of SiC MOSFETs/IGBTs in a Hybrid Connecting State

Abstract

In order to solve problems such as a slow switching speed, a high switching power, a loss of pure IGBT modulators, and the weak withstanding load short-circuit ability of pure SiC MOSFET modulators used for vacuum loads, this paper proposes a new scheme for high-voltage pulse modulators based on SiC MOSFET/IGBT hybrid connecting circuits. It has a low power loss like the pure SiC MOSFET modulator and a strong withstanding load short-circuit ability like the pure IGBT modulator. Firstly, the principle circuit of the hybrid connecting modulator are discussed and chosen. And the basic working processes of the hybrid parallel-series modulator is described in detail. Secondly, three key points in this new scheme are analyzed and designed as follows: the static and dynamic voltage sharing; the actualizing of the ZVS process for IGBTs; the improvement of short-circuit protection for SiC MOSFETs. A modulator consisting of 16-stage 1200 V-SiC MOSFETs and 1200 V-IGBTs in hybrid parallel-series states is tested. Based on the sample circuit, the working data, such as high-voltage pulse waveforms of 10 kV/2 KHz/10 μs, static and dynamic voltage sharing, the driving control sequence, the U/I sequence of the IGBT, the short-circuit protection waveform, and the calculation, are obtained and discussed.