A switching device is provided. The apparatus includes a switching circuit and a noise filter. The switching circuit is capable of switching a connection destination of a first power conversion circuit other than a second power conversion circuit among the plurality of power conversion circuits between a phase corresponding to the first power conversion circuit and a certain phase of the external power supply. The second power conversion circuit corresponds to the certain phase of the external power supply. In the noise filter, a capacitor is provided on a side of the multiple-phase AC supply of the switching circuit.

A protection circuit protects a rectifier circuit from an inrush current inputted to a smoothing circuit. A short-circuiting circuit does not short the protection circuit while an inrush current may occur, and shorts it while an inrush current does not occur. A transformer has a primary winding, a secondary winding and an auxiliary winding. A delay circuit delays a timing at which an operation of a load connected to the auxiliary winding is started with respect to a timing at which an operation of the short-circuiting circuit is started. A rectifying and smoothing circuit generates an output voltage by rectifying and smoothing the secondary side voltage. The short-circuiting circuit is driven by the output voltage.

A precharge system and method are provided. The precharge system comprises a load circuit, a precharge circuit and a control circuit. The load circuit comprises an input terminal, an input switch and a bus capacitor. The precharge circuit comprises a precharge resistor and a precharge switch. The precharge method comprises: during the load circuit being in a precharge mode, controlling the input switch to be in an off state, and controlling the precharge switch to switch between the on and off state for multiple times; and during the load circuit being in a work mode, controlling the input switch to be in an on state. During the load circuit being in the precharge mode, when the precharge switch is in the on state, a consuming power of the precharge resistor is larger than a threshold power and is smaller than or equal to a limit power of the precharge resistor.

An electric power supply includes a totem pole bridgeless PFC power converter. The PFC power converter includes an input for coupling to an AC power source, an output, four switching devices coupled between the input and the output, two diodes coupled between the four switching devices and the input, a first inductor coupled between the four switching devices and the two diodes, and a second inductor coupled between the two diodes and the input. Other example electric power supplies and totem pole bridgeless PFC power converters are also disclosed.

A power adaptor is provided including a housing receiving a first power cord couplable to a power source through a and a second power cord couplable to a load through a second axial end, a protective capacitor mounted on a circuit board within the housing, a first set of terminals mounted on a first side of the circuit board adjacent the protective capacitor and configured to electrically couple line and neutral wires of the first power cord to the protective capacitor, and a second set of terminals mounted on a second side of the circuit board adjacent the protective capacitor and configured to electrically couple line and neutral wires of the second power cord to the protective capacitor. The protective capacitor is configured to discharge when current draw by the load exceeds a current threshold.

A circuit includes two input nodes and two output nodes. A rectifier bridge is coupled to the input and output nodes. The rectifier bridge includes a first and second thyristors and a third thyristor coupled in series with a resistor in series. The series coupled third thyristor and resistor are coupled in parallel with one of the first and second thyristors. The first and second thyristors are controlled off, with the third thyristor controlled on, during start up with resistor functioning as an in in-rush current limiter circuit. In normal rectifying operation mode, the first and second thyristors are controlled on, with the third thyristor controlled off.

A prevention switching device is provided. The apparatus includes a switching circuit and a controller. The switching circuit includes a switching relay capable of switching a connection destination of a first power conversion circuit other than a second power conversion circuit among the plurality of power conversion circuits between a phase corresponding to the first power conversion circuit and a certain phase of the external power supply. The second power conversion circuit corresponds to the certain phase of the external power supply. The controller controls an operation of the switching relay at a zero-crossing time of an AC voltage estimated based on the AC voltage.

A control device includes a triac and a first diode that is series-connected between the triac and a first terminal of the device that is configured to be connected to a cathode gate of a thyristor. A second terminal of the control device is configured to be connected to an anode of the thyristor. The triac has a gate connected to a third terminal of the device that is configured to receive a control signal. The thyristor is a component part of one or more of a rectifying bridge circuit, an in-rush current limiting circuit or a solid-state relay circuit.

This power conversion device includes a plurality of power conversion units, a first electric field relaxation shield, a second electric field relaxation shield, and a third electric field relaxation shield. The first, the second and the third electric field relaxation shield include a first end, a second end and a third end, respectively. The first electric field relaxation shield and the second electric field relaxation shield surround the plurality of power conversion units when viewed from a direction in which the first electric field relaxation shield and the third electric field relaxation shield are overlapped each other. The third end is disposed at any position within a range from a position overlapping the first end to a position overlapping the second end when viewed from the direction in which the first electric field relaxation shield and the third electric field relaxation shield are overlapped each other.

Provided is a power supply apparatus that supplies power received from an external power supply to a load, the power supply apparatus comprising: a plurality of power supply circuitries, each of which has switching elements, that are allowed to supply power to the load separately; and a processor that controls a number of the power supply circuitries supplying power to the load according to a required power level of the load.