Abstract: A magnetic device and a method of producing the same. In one embodiment, the device includes: (1) a substantially planar printed wiring board having a plurality of traces associated therewith, (2) a magnetic core located over the board, electrically insulated from the plurality of traces and having a major axis in parallel with a plane of the board and (3) a winding assembly having a dielectric member that couples a plurality of separate electrical conductors together, the plurality of conductors overarching the core to couple with corresponding ones of the plurality of traces to form a winding for the magnetic device, the dielectric member electrically insulating the plurality of conductors from the core.

Abstract: An impedance network for passive shoot-through protection of active switches in clamp-mode topologies. In one exemplary embodiment a switch-mode converter, includes: a primary switch; an auxiliary switch coupled in series with a capacitor; and an impedance network, coupled to the primary switch and the auxiliary switch; configured to limit current during simultaneous conduction of the primary and auxiliary switches. The impedance network includes a resistor coupled in series to a diode and both in parallel with an inductor. The impedance network permits the design of a clamp-mode converter without the need for a delay between switch turn-off and turn-on of primary and auxiliary switches.

Abstract: A switching circuit, a method of processing power and a single stage power factor corrector employing the switching circuit or the method. In one embodiment, the switching circuit includes: (1) a power switch coupled to a primary winding of a transformer; and (2) an active clamp coupled to the power switch. The active clamp includes: (2a) series-coupled first and second capacitors, coupled across the power switch and the primary winding, having opposing polarities thereacross, and (2b) a clamping switch coupled to a node between the series-coupled first and second capacitors. The clamping switch opens to allow energy stored in the first capacitor to be transferred to an output of the power converter via the second capacitor. The clamping switch further closes to allow energy stored in the second capacitor to be transferred to the output.

Abstract: A controller or a method for regulating a non-isolated power factor corrector and a power factor corrector employing the controller or the method. The power factor corrector is adapted to provide a DC output voltage at an output thereof. The power factor corrector has first and second power switches, coupled to an input thereof, that receive unrectified AC power. In one embodiment, the controller includes: (1) a sensor, coupled proximate the input, that senses a polarity of the unrectified AC power and (2) a drive circuit, coupled to the sensor, that: (2a) closes the first power switch and modulates the second power switch to regulate the DC output voltage when the polarity is negative, and (2b) closes the second power switch and modulates the first power switch to continue to regulate the DC output voltage when the polarity is positive.

Abstract: An AC active clamp, a method of operating the same and a power factor corrector employing the AC active clamp or the method. The power factor corrector has a primary switching circuit coupled to a primary winding of an isolation transformer and a rectifier coupled to a secondary winding of the isolation transformer. The primary switching circuit has first and second power switches configured to receive unrectified AC power. In one embodiment, the AC active clamp includes a switching circuit having first and second clamping switches series coupled in opposition and a capacitor coupled to the switching circuit. The switching circuit and the capacitor are coupled across at least a portion of the primary winding and are configured to mitigate adverse effects of a reverse recovery phenomenon associated with the rectifier and to effect substantially zero voltage switching of the first and second power switches of the primary switching circuit.

Abstract: For use with a power converter couplable to a source of electrical energy, the converter having a power switch that conducts intermittently to transfer energy from the source to an inductive element, and a freewheeling diode that alternately conducts with the power switch to transfer energy to an output of the converter, an active clamp and a method of operating the active clamp. In one embodiment, the active clamp includes: (1) an inductor, coupled in series with the freewheeling diode, and (2) a series-coupled capacitor and clamping switch, coupled in parallel with the inductor, that cooperate therewith to mitigate adverse effects of reverse recovery currents associated with the freewheeling diode and enable substantially zero voltage switching of the power and clamping switches.

Abstract: A circuit associated with a power converter, a method of operation thereof and a power converter employing the circuit or the method. The power converter has a primary switching circuit coupled to a tapped primary winding of an isolation transformer and a rectifier coupled to a secondary winding of the isolation transformer. The circuit is coupled across a tapped portion of the tapped primary winding. In one embodiment, the circuit includes: (1) an inductor, configured to reduce current spikes in the primary switching circuit caused by a reverse recovery phenomenon associated with the rectifier and to effect substantially zero voltage switching of a power switch of the primary switching circuit; and (2) a diode, coupled to the inductor via the tapped portion, configured to clamp a voltage across the rectifier. The tapped portion is configured to enable energy from the inductor to be recovered within the power converter.

Abstract: A boost converter, a method of converting power and a power supply incorporating the boost converter or the method.

Abstract: A secondary active clamp for a power converter, a method of actively clamping energy of the power converter and a power converter employing the clamp or the method. The power converter has a primary switching circuit coupled to a primary winding of an isolation transformer and a rectifier coupled to a secondary winding of the isolation transformer. In one embodiment, the clamp includes (1) an inductor coupled in series with a freewheeling diode of the rectifier and (2) a series-coupled capacitor and clamping switch coupled in parallel with the inductor. The series-coupled capacitor and clamping switch cooperate with the inductor to mitigate adverse effects of a reverse recovery phenomenon associated with the rectifier and to effect substantially zero voltage switching of a power switch of the primary switching circuit.

Abstract: A single stage power converter, a method of processing rectified AC power, and a power supply incorporating the converter or the method. In one embodiment, the converter is couplable via a rectifier to a source of AC power, has a filter capacitor and an isolation transformer with a primary winding, and includes: (1) a significant energy storage device coupled to the primary winding, (2) a first switch, coupled to the primary winding, that conducts intermittently to couple the primary winding to the rectifier to transfer a portion of rectified AC power to a magnetizing inductance of the isolation transformer and (3) a second switch, coupled between the primary winding and the significant energy storage device, that conducts alternately with the first switch, the first and second switches substantially zero-voltage switching and the converter correcting a power factor of the AC power.

Abstract: The present invention relates to a power converter which uses pulse width modulated (PWM) control to provide a galvanically isolated dc output. Topologically, the converter uses a full-bridge switching scheme with a boost converter, and can be referred to as an isolated boost converter. The converter includes an ancillary circuit comprised of a switch transistor and a series connected capacitor which act as an active clamp. The converter of the present invention allows for a number of significant advantages. The converter provides zero voltage transitions in all switches, thereby preventing losses due to leakage currents in the switching transistors during switching transitions. The converter further provides a path for transformer magnetizing current flow, and also clamps the leakage inductance related to voltage spikes across the switches. These advantages allow the converter to keep stress on the active components low which makes the circuit more efficient.

Abstract: An isolated flyback secondary inductor converter (IFSIC) and method of operation thereof. The IFSIC has a transformer with a primary winding for receiving electrical energy from a source of electrical power and a secondary winding coupled to the primary winding. The IFSIC also has a switch for intermittently coupling the transformer to the source of electrical power. The IFSIC includes a series-coupled inductor and diode coupled in parallel with the secondary winding to provide a path for the energy from the transformer when the transistor is ON, allowing the energy to be stored in the inductor rather than in the transformer.

Abstract: An asymmetrical power converter and a method of operation thereof. According to a first aspect of the present invention, the asymmetrical converter includes (1) first and second transformers having serially-coupled primary windings and differing turns ratios; (2) a first power switch coupled to a first end of the serially-coupled primary windings; (3) a second power switch coupled to a node between the serially-coupled primary windings and (4) a capacitive element coupled to a second end of the serially-coupled primary windings to maintain a volts-second balance thereacross during alternate switching cycles of the first and second power switches.

Abstract: A single stage power converter has an energy storage device and is configured to receive electrical power. The single stage power converter includes: (1) an inductor, coupled to the energy storage device, for affecting a voltage across the energy storage device, (2) an asymmetrical half-bridge power circuit coupled to the energy storage device and having first and second power switches capable of being alternately activated to conduct current from the energy storage device to an output thereof and (3) a controller for controlling activation of the first and second power switches as a function of a characteristic of the output thereby to enhance a regulation of the output.

Abstract: A voltage stress (e.g., reverse voltage stress) in rectifying diodes of, for instance, an asymmetrical DC-to-DC converter is reduced by using a transformer circuit having multiple power transformers with a composite static transfer characteristic. More specifically, the static transfer characteristic is selected to be monotonic in combination with the transformer circuit including two transformers, having independent isolated cores, coupling an input to output of the converter. A primary to secondary winding ratio of each of the two transformers is selected in such a way as to achieve a reduction in reverse voltage in at least one of the rectifying diodes. The reduction in the reverse voltage and, hence, improved efficiency of the rectifier is directly translatable into an increase in a power density of the converter.

Abstract: An integrated power converter and a method of operation thereof. The integrated power converter, having an energy storage device, includes: (1) a conditioning circuit coupled to the energy storage device and having a control switch for affecting a voltage across the energy storage device, (2) an asymmetrical half-bridge power circuit coupled to the energy storage device and having first and second power switches capable of being alternately activated to conduct current from the energy storage device to an output thereof and (3) a controller for controlling activation of both the control switch and the first and second power switches as a function of a characteristic of the output thereby to enhance a regulation of the output.

Abstract: Holdover circuitry for an off line switcher, including a DC-to-DC converter, maximizes holdover time, during source voltage failures, by commutating a precharged holdover capacitor to the input of a power factor correcting preregulator. This limits the size of the holdover capacitor required without any loss in holdover time. Reduction in the size of the required holdover capacitor required for a desired holdover time improves volumetric efficiency of the off line switcher. This arrangement further improves efficiency of the DC-to-DC converter and decreases stress on its components by narrowing the input voltage range requirement.

Abstract: A SEPIC converter powered off line is controlled to improve the input power factor by forcing the current in the input inductor to assume the same wave shape as the voltage across the inductor in series with the power switch to insure a sinewave input current. A switched capacitor is provided to provide brief holdover power to the converter should the input AC voltage fail.

Abstract: A single ended forward converter periodically resets the transformer core to prevent saturation and returns magnetizing energy to the energy source, requiring only the addition of one resonating capacitor to the converter circuit.The transformer is reset and the energy recovered into the input voltage source by resonant commutation of the magnetizing current between the magnetizing inductance and a resonating capacitor. A resonant current path is completed during a nonconducting interval of the power transistor switch through a resonating capacitor, shunting the output rectifying diode connected to the secondary winding, and the flyback diode of the output filter to permit transfer of the transformer's magnetizing energy to the input energy source. This magnetizing energy transfer from core to capacitor to input energy source has a resonant quasi-sine waveform and utilizes the resonant properties of the network to enable its flow back into the input voltage source.