A protection circuit includes a pre-charge rectifying circuit, a pre-charge resistor, a varistor, a switch, a main rectifying circuit, a bulk capacitor, and a control circuit. The pre-charge rectifying circuit is connected with an AC power source. The pre-charge resistor and the varistor are connected between the pre-charge rectifying circuit and the switch. The switch is further connected with a first node. The main rectifying circuit is connected between the AC power source and the first node. The bulk capacitor and the control circuit are connected between the first node and a ground terminal. The control circuit generates a first control signal to control the switch. The control circuit further generates a control signal set to control the main rectifying circuit.

A power conversion apparatus comprises a circuit, a detection section and a control section. The control section supplies a pulse signal for enabling the first switch and the second switch to be opened and closed alternately according to a polarity of the alternating voltage power supply so that a sine wave current synchronized with a voltage phase of the alternating voltage power supply flows to the alternating voltage power supply on the basis of the voltages and current obtained from the detection section.

The control apparatus is used with the electrical power converter working to an inputted one of ac voltage and a terminal-to-terminal voltage at a capacitor into the other. The control apparatus calculates a sine-wave command value for a reactor current based on the ac voltage and an amplitude command value indicating an amplitude of the reactor current. The control apparatus also operates switches SW in peak-current mode control to bring the reactor current into agreement with a command value for the reactor current to which a current correction value is added. The control apparatus sets the current correction value to include a component of fluctuation in the terminal-to-terminal voltage at the capacitor based on the ac voltage Vac.

A main circuit of a power conversion device includes: an AC/DC converter for performing power factor correction control for a single-phase AC power supply; and a DC/DC converter connected to the AC/DC converter via a DC capacitor. In order to reduce ripple voltage and ripple current for the DC capacitor, a control circuit superimposes, onto a DC current command, an AC current command having the minimum value at the zero cross phase of the single-phase AC power supply and having the maximum value at the peak phase thereof, to generate an output current command for the DC/DC converter, and performs output control for the DC/DC converter, using the output current command.

A power converter circuit includes a switching circuit with at least one electronic switch, a capacitor configured to provide or receive a voltage with a predefined voltage level, at least one first inductor, and a snubber circuit. The snubber circuit includes at least one second inductor inductively coupled to the at least one first inductor and electrically coupled to the capacitor.

A converter circuit regulating power transfer from a power source to a load includes a first switching circuit arranged to be connected across an output of the power source, and including a plurality of switches. A second switching circuit including a plurality of switches is arranged to be connected across an input of the load. An inductive component electrically connects the first switching circuit with the second switching circuit. A controller is operably connected with the plurality of switches in both the first and second switching circuits, and receives a control signal for controlling switching of the plurality of switches in both the first and second switching circuit; generates gating signals to be provided to the plurality of switches in both the first and second switching circuit based on the control signal; and provide the gating signals to the plurality of switches in both the first and second switching circuit.

The present application relates to AC power supplies and in particular to power factor correction circuits in AC-DC converters. The application provides an active power factor correction circuit in which zero voltage switching is inherently achieved using a passive snubbing approach employing a saturable transformer.

A bridgeless converter includes a boost inductor connected in series with an alternating-current power source, a first series circuit including a first switching device and a second switching device connected in series with each other, a second series circuit including a third switching device and a fourth switching device connected in series with each other, a capacitor connected in parallel with the first series circuit and the second series circuit, and a magnetization sensing circuit including at least one auxiliary winding inductively coupled to the boost inductor.

The present application relates to switching power supplies and in particular to AC to DC switch mode power supplies, to methods of power factor correction for same and to devices and circuits that may be used generally in same. The application describes a number of multi-level approaches and circuits.

An electric power conversion device includes a transformer composed of three or more windings magnetically coupled with each other, wherein power supply sources, are connected to at least two windings, via switching circuits, a load is connected to at least one winding, and a control circuit temporally divides, within one switching period, a total ON time during which power is supplied, in accordance with the number of the power supply sources, to supply power, the one switching period being the minimum repetitive unit during which power is supplied alternately. The control circuit allocates the divided ON times to the respective switching circuits, and the switching circuits, supply power from the power supply sources, to the load side during the allocated ON times, respectively.