Abstract: A device to drive a plurality of power switches in a power converter with an input voltage port having an input voltage comprises a drive resonant tank, a switch network, a control block configured to control the turn-on and turn-off of drive switches, and an output port. The drive resonant tank comprises a resonant inductor, and a resonant capacitor which comprises an input capacitance of a power switch. The switch network has a plurality of drive switches, which are controlled such that the drive resonant tank goes through a resonant state and a pseudo clamp state consecutively during a switching period. A gate drive voltage of a power switch fluctuates slightly during the pseudo clamp state. The output port has two terminals coupled to a gate and a source of a power switch respectively.

Abstract: A device comprises a motor/generator having an air gap and a plurality of windings, a plurality of power converter groups, and a control system. The windings are so configured that the number of phases in a pair of poles and the number of poles of the motor/generator can be dynamically adjusted. The power converter group comprises a plurality of power converters which is coupled between an input voltage source and a plurality of windings for controlling currents in the windings. The control system is so configured such that the number of poles of the motor/generator and the number of phases in a pair of poles are dynamically adjusted, and a synchronous speed of a moving magnetic field generated by winding currents within first pair of poles is approximately equal to a synchronous speed of a second moving magnetic field generated by currents in the windings within second pair of poles.