Design of Modular Auxiliary Gate Driver Power Supply for Medium Voltage Converter System

Auxiliary Power supplies are necessary for powering the gate drivers and controller circuits used in converter operation. Designing auxiliary power supplies for generating very low voltage output (up to 20V) from medium voltage DC input (6kV to 10kV) is technically challenging. Currently, lot of research is being carried out in implementing grid level medium voltage converters using 6.5kV to 10kV SiC MOSFETs. Fast switching speed of SiC devices induces common mode noise into the gate driver system. Apart from generating a DC output for gate drivers, the power supplies also need to provide the necessary isolation and common mode current protection resulting from fast switching. This paper discusses a novel power supply topology to generate an isolated low Voltage output from a high voltage input up to 2kV. A scheme has been proposed to achieve low DC output from Medium Voltage input (6kV to 10kV) by series input and parallel output connection of auxiliary power supply modules. Theoretical analysis of proposed topology has been formulated and hardware implementation has been done to verify operation of the topology.