Self-powered bipolar gate-driver power supply circuit for neutral-point-clamped converters

The design of gate-driver power supply (GDPS) circuits for multilevel neutral-point-clamped converters is a challenge due to the large number of power switches required and the fact that each device presents a different GDPS reference node. This paper presents a compact self-powered bipolar GDPS circuit, consisting of two subcircuits connected across the power switches, which altogether produce all the positive and negative supply voltages required by the GDs. As these subcircuits essentially contain semiconductor components, they can be integrated with the power switch and gate driver, to produce a compact cell from which obtain a compact converter leg implementation. Overall, this BGDPS design is suitable for all types of NPC multilevel topologies with any type of power transistor, although it is most suitable for moderate device voltage ratings. The good performance of the proposed BGDPS circuit has been confirmed through experiments on a conventional two-level leg, and on three-level and four-level active-clamped converter legs.