Abstract: A zero voltage transition, ZVT, auxiliary circuit for a multi-level power converter. The ZVT auxiliary circuit includes first and second solid state auxiliary switches connected in series across a series connection of an input voltage and an input inductor, and an auxiliary inductor Laux connected at one end between the first and second solid state auxiliary switches, the other end being arranged to be connected between two switching stages of the multi-level power converter, in use.

Abstract: A snubber circuit to mitigate voltage overshoot in a power train for driving a motor, the snubber circuit configured to be connected to the motor terminal between a transmission line from a power supply and converter and a motor. The snubber circuit includes a rectifier, a capacitor connected across an output of the rectifier and a load connected across the capacitor. The capacitor is rated to charge to a predetermined link voltage and wherein an input voltage to the rectifier that exceeds the link voltage causes the voltage at the motor terminal to clamp to the link voltage and for excess energy from the input voltage to be stored in the link capacitor and dissipated by the load.

Abstract: A series resonant power converter, comprising: a first plurality, m, of resonant power converter modules, each comprising a switching stage, a resonant tank, a transformer, a rectifier stage and an output capacitor, the plurality of resonant power converter modules connected in series across a power supply, the resonant power converter further comprising a common output stage (500) connected across the series-connected plurality of resonant power converter modules, whereby a second plurality, n, of output levels at the common output stage.

Abstract: An active electromagnetic interference filter comprising an adjustable shunt impedance circuit, the adjustable shunt impedance circuit comprising a noise sensing branch that senses input noise and provides a noise voltage representative of the sensed noise, and an operational amplifier stage configured to generate, at an injection branch, an injection current based on the noise voltage.