A DC-DC converter may include: a first converter for converting an input voltage to generate a first power supply voltage; a duty ratio controller configured generate a duty ratio control signal for controlling a duty ratio of a switching pulse of the first converter; a switching frequency controller configured to generate a switching frequency control signal for controlling a driving frequency of the first converter corresponding to a switching frequency of the switching pulse; and a current sensor configured to sense current flowing through the first converter. The first converter is driven at a switching frequency of a first frequency in a first mode, based on the switching frequency control signal, and generates the first power supply voltage of a first level, based on the duty ratio control signal. The switching frequency controller determines whether to turn off the current sensor.

A circuit for igniting and sustaining an electron discharge includes an ignitor circuit. The igniter circuit includes a high voltage transformer and a switch connected in series between a primary of the transformer and a DC source return. The switch is configured to receive a driving signal. A reset circuit is connected in parallel to the primary of the high voltage transformer. A first rectifier is connected in series between a secondary of the high voltage transformer and a keeper. A terminal of the secondary of transformer is connected to a cathode. The circuit for igniting and sustaining the electron discharge also includes a sustaining circuit having a current source with a return connected to a cathode and a second rectifier connected in series between the current source and the keeper.

A DC/DC converter may be formed out of the combination of a first converter that is optimized to transfer energy from a voltage source to a load, and a second converter that receives a control signal derived from the load voltage to regulate the load voltage. The DC/DC converter may be configured as a sigma converter, a delta converter, or a sigma-delta converter. The mode of operation being selected according to the source voltage or the load voltage, either of which may vary over a wide range.

A charging device includes a first DC convertor and controller. The first DC convertor is configured to convert a DC signal outputted by a power battery to a DC signal required for a storage battery. The first DC convertor includes a first half-bridge logical link control (LLC) circuit and a second half-bridge LLC circuit arranged in parallel. The controller is connected with the first half-bridge LLC circuit and the second half-bridge LLC circuit and configured to acquire a total output current of the first DC convertor, and control the first half-bridge LLC circuit and the second half-bridge LLC circuit to operate alternately when the total output current is less than a current threshold.

A power conversion system includes N power converters. Each power converter includes an input terminal, a first output terminal and a second output terminal. Each of the N power converters receives a DC power through the corresponding input terminal. The first output terminal of a first power converter of the N power converters and the second output terminal of an N-th power converter of the N power converters are connected in parallel to form an N-th total output terminal to output an N-th total output power. The first output terminal of an i-th power converter of the N power converters and the second output terminal of an (i−1)-th power converter of the N power converters are connected in parallel to form an (i−1)-th total output terminal to output an (i−1)-th total output power.

A voltage conversion circuit includes an N-level conversion unit and N-1 DC-DC conversion units. The N-level conversion unit includes N output terminals at different levels. A first input terminal of the M.sup.th DC-DC conversion unit is connected to the M.sup.th output terminal of the N-level conversion unit, and a second input terminal of the M.sup.th DC-DC conversion unit is connected to an (M+1).sup.th output terminal of the N-level conversion unit. An output level of the M.sup.th output terminal and an output level of the (M+1).sup.th output terminal are adjacent levels. N and M are positive integers and satisfy N ≤ 3 and 1 ≥ M < N.

A power supply system includes a power conversion circuit that is connectable to a power storage unit. The power supply system includes a control unit and a heat transferring unit. The control unit supplies a current between the power storage unit and the power conversion circuit by performing on-off control of a switch that configures the power conversion circuit. The heat transferring unit absorbs heat that is generated in the power conversion circuit in accompaniment with the on-off control of the switch and transfers the heat to a temperature-increase target element. The control unit performs temperature-increase mode control in which the switch is on-off controlled such that an amount of heat that is generated in the power conversion circuit is increased when a temperature-increase request for the temperature-increase target element is present, compared to when the temperature-increase request is not present.

A DC-DC converter may include: a first converter for converting an input voltage to generate a first power supply voltage; a duty ratio controller configured generate a duty ratio control signal for controlling a duty ratio of a switching pulse of the first converter; a switching frequency controller configured to generate a switching frequency control signal for controlling a driving frequency of the first converter corresponding to a switching frequency of the switching pulse; and a current sensor configured to sense current flowing through the first converter. The first converter is driven at a switching frequency of a first frequency in a first mode, based on the switching frequency control signal, and generates the first power supply voltage of a first level, based on the duty ratio control signal. The switching frequency controller determines whether to turn off the current sensor.

Power module includes transformer unit including primary and secondary windings and magnetic core; first and second capacitor units coupled to first terminal of primary winding of transformer unit through first node; first and second external pins respectively coupled to first terminal of first capacitor unit and second terminal of second capacitor unit; first and second switch units coupled to second terminal of primary winding of transformer unit thorough second node; third and fourth external pins respectively coupled to first terminal of first switch unit and second terminal of second switch unit; secondary-side circuit coupled to secondary winding; and fifth and sixth external pins electrically coupled to first and second output terminals of secondary-side circuit, respectively. First external pin is coupled to one of third and fourth external pins selectively.

A power conversion module includes a first bridge arm, a second bridge arm, a transformer and a rectifying circuit. An output positive terminal and an output negative terminal are electrically connected with a low-voltage and high-current load. The first bridge arm and the second bridge arm are electrically connected between an input positive terminal and an input negative terminal. The transformer includes a primary winding, a first secondary winding and a second secondary winding. The two terminals of the primary winding are electrically connected with a midpoint of the first bridge arm and a midpoint of the second bridge arm. An output inductor of the rectifying circuit is electrically connected between the winding midpoint and the output positive terminal. The input voltage is higher than 40 V. The output voltage is lower than or equal to 2.2 V.