Abstract: A lossless clamping circuit for use in a synchronous rectifier DC-DC converter in which at least one transistor switch (MOSFET) periodically connects two terminals of an output transformer winding across a main output and return terminal to provide a DC current at a selected voltage for a load connected between the output and reference terminals. A diode and an auxiliary capacitor are connected in series across the MOSFET's drain source so that the capacitor accumulates a charge in accordance with the reverse recovery current in the winding leakage inductance when the MOSFET is turned off and an auxiliary DC-DC converter is connected to the auxiliary capacitor for converting the accumulated charge across the capacitor to a DC current at a selected output voltage. Preferably the output of the auxiliary DC-DC converter is connected to the main output terminal to supplement the output power.

Abstract: A motor has a stationary assembly including three windings in magnetic coupling relation to a rotatable assembly, the position of which is sensed by a position sensor. A converter, adapted to be coupled to a power supply, energizes each of the windings with a voltage. The converter is responsive to the angular position and speed of the rotatable assembly for selectively energizing each of the windings according to a preselected sequence. The converter energizes each winding with the voltage throughout a commutation period when a back EMF induced in such winding has a polarity opposite to a polarity of the voltage energizing such winding, the commutation period for each winding overlapping the commutation period for another winding. Alternatively, the converter energizes each winding with the voltage throughout a commutation period of 180 electrical degrees, the commutation period for each winding overlapping the commutation period for another winding.

Abstract: Control circuit for an electronically commutated motor which has a rotatable assembly and further has a stationary assembly with a plurality of winding stages having terminals for energization, and switches for applying a voltage to one or more of the terminals of the winding stages at a time and commutating the winding stages in a preselected sequence to rotate the rotatable assembly. A preselected sequence of winding stages are left correspondingly unpowered so that a plurality of the winding stages are unpowered at some time. The winding stages generate back emf signals and also couple electrical signals from each energized winding stage to the unpowered winding stages which signals can interfere with detection of back emf for position sensing purposes. The control circuit includes a first circuit for selecting at least two of the unpowered winding stages which have electrical signals coupled to them that have a predetermined relationship in polarity and magnitude.