Active gate control for current balancing in parallel connected IGBT modules in solid state modulators

In modern pulsed power systems often fast solid state switches like MOSFETs and IGBT modules are used to generate short high power pulses. In order to increase the pulsed power, solid state switches have to be connected in series or in parallel. Depending on the interconnection of the switches, parameter variations in the switches and in the system can lead to an unbalanced voltage or current. Therefore, the switches are generally derated, which results in an increased number of required devices and volume. With an active gate control, derating and preselection of the switching devices can be avoided. In this paper an active gate control of paralleled IGBT modules, which has been developed for converters with inductive load, is explained in detail and adapted to a solid state modulator. There, the paper focuses on the low inductance IGBT current measurement, the control unit implementation with a FPGA and DSP, as well as the balancing of the pulse currents.