An electric power conversion device has a transformer, a DC-AC conversion circuit, an AC-DC conversion circuit and a control circuit. The control circuit calculates an input current instruction value (Iref) based on a difference value (ΔV) between an output voltage (Vout) of the AC-DC conversion circuit and an output voltage instruction value (Vref). A comparator compares an input current (Iin) of the DC-AC conversion circuit with the value (Iref). The DC-AC conversion circuit is controlled by the comparison result of the comparator. The control circuit correctly determines an occurrence of an abnormality state of the electric power conversion device based on the operation state of the comparator, the difference value (ΔV) between the output voltage (Vout) of the AC-DC conversion circuit and the output voltage instruction value (Vref), and the input voltage (Vin) of the DC-AC conversion circuit without using any output current of the AC-DC conversion circuit.

An apparatus may include an input circuit to receive an AC input voltage having a first magnitude within a range of AC input voltages, and generate a first DC voltage; a boost converter to receive the first DC voltage and output a second DC voltage having a fixed magnitude that is not dependent upon the first magnitude of the AC input voltage; an output circuit to receive the second DC voltage and convert the second DC voltage into welding type power; a control DC-DC converter to receive the first DC voltage and output a control power signal as a third DC voltage; a boost converter control component to receive the control power signal and generate a control signal to control operation of the boost converter; and an auxiliary AC power source to receive the second DC voltage output by the boost converter and to generate an AC auxiliary output voltage.

A power conversion device which is a test target performs DC voltage conversion between a primary side DC terminal and a secondary side DC terminal. A first connection member electrically connects a testing power supply and the primary side DC terminal serving as an input side of the test target. A second connection member electrically connects the primary side DC terminal and the secondary side DC terminal of the power conversion device to transmit active power output from the secondary side DC terminal to the primary side DC terminal to be a part of active power input to the primary side DC terminal.

A control device controls a switching circuit for a converter. The switching circuit comprises a half-bridge having a high-side transistor and a low-side transistor. The control device comprises a controller configured to control turning on and turning off said two transistors, so that a square-wave voltage is applied to the transformer primary. The controller is configured to start switching the half-bridge by turning on the low-side transistor. The control device comprises a first timer configure to initially turn on the low-side transistor for a duration given by a first time period useful for pre-charging a bootstrap capacitor couplable to the middle point of the half-bridge, and a second timer configured to keep the low-side transistor and the high-side transistor turned off for a second time period immediately following the first time period and having a longer duration than the first time period.

The present invention provides a driving device and a control method. The driving device is configured to drive a power switch and includes a power supply, a first bridge arm coupled to the power supply, a second bridge arm coupled in parallel to the first bridge arm, and a resonant inductor. The first bridge arm includes a first switch and a second switch connected to a first midpoint, the second bridge arm comprises a first semiconductor element and a second semiconductor element connected to a second midpoint, and the resonant inductor is coupled between the first midpoint and the second midpoint. The control method includes turning on the first switch for a first period such that the power supply charges a gate electrode of the power switch; and in response to a decrease of a current of the resonant inductor to a first threshold value, turning on the first switch again for a second period such that a potential of the first midpoint is equal to a potential of the second midpoint.

The present invention provides a driving device and a control method. The driving device is configured to drive a power switch and includes a power supply, a first bridge arm coupled to the power supply, a second bridge arm coupled in parallel to the first bridge arm, and a resonant inductor. The first bridge arm includes a first switch and a second switch connected to a first midpoint, the second bridge arm comprises a first semiconductor element and a second semiconductor element connected to a second midpoint, and the resonant inductor is coupled between the first midpoint and the second midpoint. The control method includes turning on the first switch for a first period such that the power supply charges a gate electrode of the power switch; and in response to a decrease of a current of the resonant inductor to a first threshold value, turning on the first switch again for a second period such that a potential of the first midpoint is equal to a potential of the second midpoint.

The invention relates to a drive circuit for operating an illuminant, preferably at least one LED, comprising an isolated converter which is clocked on the primary side by a control unit by means of at least one controlled switch unit, said converter supplying a rectifier starting from which the illuminant can be fed, a measurement circuit for indirectly measuring the current on the secondary side of the converter having a transformer with at least one winding on the primary side.

Provided are methods and circuits for a resonant converter comprising at least one switch-controlled capacitor, wherein the at least one switch-controlled capacitor controls a resonant frequency of the resonant tank circuit. Provided are constant and variable switching frequency embodiments, and full-wave and half-wave switch-controlled capacitor embodiments. Also provided are interleaved resonant converters based on constant and variable switching frequency, and full-wave and half-wave switch-controlled capacitor resonant converter embodiments. Interleaved embodiments overcome load sharing problems associated with prior interleaved resonant converters and enable phase shedding to improve light load efficiency.

A polarity-selectable high voltage direct current power supply including a first drive assembly that transforms a first low voltage DC input into a first medium voltage alternating current output; a first HV output assembly that transforms the first LV AC output into a first HV DC output, wherein the first HV output assembly defines a first input stage; a polarity selector coupled between the second output junction of the first drive assembly and the first and second input stages of the first HV output assembly, the polarity selector operable between a first configuration and a second configuration; wherein in the first configuration the first HV DC output has a positive polarity; and wherein in the second configuration the first HV DC output has a negative polarity.

An electrical circuit for providing electrical power for use in powering electronic devices is described herein. The electrical circuit includes a power converter circuit that is electrically coupled to an electrical power source for receiving alternating current (AC) input power from the electrical source and delivering direct current (DC) output power to an electronic device. The power converter circuit includes a transformer and a switching device coupled to a primary side of the transformer for delivering power from the electrical power source to a primary side of the transformer. A controller is coupled to a voltage sensor and the switching device for receiving the sensed voltage level from the voltage sensor and transmitting a control signal to the switching device to adjust the voltage level of power being delivered to the electronic device.