The power supply apparatus including a high-voltage generation unit generating a DC voltage VA includes a Zener diode that drops the DC voltage VA to a DC voltage VB, a resistor connected to a line to which the DC voltage VA is output, and a voltage divider that generates a DC voltage VC by dividing the DC voltage VA with the resistor, and the voltage divider adjusts the DC voltage VC such that the potential difference between the DC voltage VB and the DC voltage VC is within a predetermined range.

Systems and methods for an alternating current (AC) input selection for a power transformer are disclosed. In particular, a connector is provided that is pre-wired to utilize internal wiring in the power transformer to provide a desired connection. A first option allows two transformers' input winding to be in series while a second option allows the two transformers' input winding to be in parallel. By moving the wiring into the connector, installation is simplified as the wiring has already been done. The installer need only attach the correct plug based on the desired voltage and couple the plug to the transformer. Further, the manipulation of thick wires is also avoided by the installer, further simplifying the installation process.

A current output apparatus adapted for electrical connection to a load to output an electrical current thereto. The apparatus comprises a current output terminal for connecting to a first terminal of the load to pass an electrical current thereto. A current input terminal is provided for connecting to a second terminal of the load to receive said electrical current returned from the load. A voltage regulator is operable to supply to the current output terminal an electrical voltage regulated to differ from an electrical voltage applied to the current input terminal by an amount sufficient to cause said electrical current to flow from the current output terminal to the current input terminal via the load. The voltage regulator is operable and arranged to supply to the current output terminal an electrical voltage of positive polarity or of negative polarity for supplying said electrical current to a load presenting to the current output terminal a voltage of positive polarity or of negative polarity, respectively.

An apparatus includes: a switched capacitor (SC) converter to generate a first voltage based on a voltage source; and a direct current-to-direct current (DC-DC) converter to generate a second voltage based on the voltage source of the apparatus. A difference between the first voltage and the second voltage corresponds to an output voltage.

A voltage control circuit comprises a sampling sub-circuit and a control sub-circuit. The sampling sub-circuit is configured to detect a potential difference between an output voltage and an input voltage to obtain a first voltage and output the first voltage to the control sub-circuit. The control sub-circuit is configured to compare a magnitude of the first voltage with a first voltage threshold, if the first voltage is less than the first voltage threshold, output the input voltage as the output voltage, and, if the first voltage is greater than or equal to the first voltage threshold, superimpose and output the input voltage and a bootstrap voltage as the output voltage.

Examples of power converter circuits and power conversion methods are disclosed. One example of a power converter circuit includes an input configured to receive an input voltage and an output configured to provide an output voltage; a main converter coupled between a main converter input and the output and comprising a first winding and a second winding that are inductively coupled; and an auxiliary converter comprising an auxiliary converter input coupled to a third winding and an auxiliary converter output, wherein the third winding is inductively coupled with the first winding and the second winding. The auxiliary converter output is coupled between the input and the main converter input.

An electrical-power-supplying device for a wall plug includes a first DC-DC power converter including a first output and a second output; a second DC-DC power converter the input of which is connected to the second output; and a first capacitor connected to the input of the first converter, a second capacitor connected to the first output and a third capacitor connected to the second output. The first output of the first converter and the output of the second converter are connected in series to form an output of the power-supplying device able to deliver a DC voltage, the power-supplying device including at least one fourth capacitor that is connected to the output of the second converter or to the output of the power-supplying device.

According to the present embodiment, a DC transformation system includes a rectifier, a first power conversion device, a second power conversion device, and a control device. The rectifier rectifies AC power supplied from an AC power source and outputs a first DC voltage. The first power conversion device is connected in series to the rectifier and outputs a second DC voltage. The second power conversion device is connected in parallel to the rectifier and converts power supplied from the rectifier to supply the converted power to the first power conversion device. The control device controls the first power conversion device to cause an addition/subtraction voltage of the first DC voltage and the second DC voltage to be a predetermined voltage.

A power conversion device includes: a power conversion circuit for converting DC power into AC power; and a controller to generate a control signal for the power conversion circuit based on a control command value and an output voltage of the power conversion circuit. The controller is configured to generate the control signal based on a corrected voltage command value calculated by subtraction correction to decrease a voltage command value when the output voltage of the power conversion circuit is equal to or higher than a predetermined threshold value, and to generate the control signal based on a voltage command value not subjected to the subtraction correction when the output voltage of the power conversion circuit is lower than the threshold value.

A system may be provided that may include a first battery, and an inverter coupled to the battery. The system may also include a first active filter including a first switch element, second switch element, third switch element, and fourth switch element. Each switch element may be coupled to the first battery or the inverter. The first, second, third, and fourth switch elements may be configured to increase or decrease an applied voltage or current of the first battery.