Abstract: An power converter that is operable to convert AC power into DC power that may be delivered to a load. The power converter includes a transformer and a controllable switch. The switching frequency of the power converter is configured to be dependent on the level of the AC voltage of an AC power source. The switching frequency may be proportional to the AC voltage to provide a constant magnetic flux density swing for the transformer in the power converter. The switching frequency may be controlled by using a circuit that converts the AC voltage from the AC power source into a frequency signal that is proportional to the AC voltage.

Abstract: A high efficient input current shaping AC to DC converter with PFC front end that reduces input current harmonics is provided. In one embodiment, an AC to DC converter connectable with an alternating current source and operable to output a direct current comprises a PFC front end followed by a DC/DC converter. The PFC front end reduces harmonic components present in an input current waveform received by the PFC front end from the alternating current source and includes current steering circuitry and, optionally, valley filling circuitry. The DC/DC converter comprises one that presents pure resistive input impedance to the PFC front end. The DC/DC converter outputs the direct current to a load connected thereto.