Voltage Balancing Method for Series-Connection of 50 SiC MOSFETs

Inhalt:
Silicon Carbide (SiC) MOSFETs above 3.3 kV are expensive and not yet commercially available. Partly because of this, medium voltage (MV) converters use multi-level architectures that are far more complex to design and maintain. In order to simplify the design of MV converters by using a two-level topology, this paper introduces a synthetic MV switch made up of 48 series-connected 1.2 kV SiC MOSFETs. As such series-connected switches suffer from dynamic voltage unbalancing issues; this paper discusses a new method for the voltage balancing of a series-connection of near 50 transistors, using a voltage clamping circuit and an associated command scheme for gate delay control.