US Patent 7791905 Electrical DC-DC power converter with magnetically coupled switch control circuit

Power converter with a controllable first switch and a diode and a controllable second switch and a second diode, a transformer with a primary winding and a secondary winding, of which the secondary winding forms at least part of a control circuit for the first switch. As a result of an alternating voltage across the primary winding, a synchronously alternating voltage is induced in the secondary winding, which can be used to control the first switch essentially synchronously with the second switch.