Abstract: This invention provides a current control semiconductor element in which dependence of a sense ratio on a temperature distribution is eliminated and the accuracy of current detection using a sense MOSFET can be improved, and to provide a control device using the current control semiconductor element. The current control semiconductor element 1 includes a main MOSFET 7 that drives a current and a sense MOSFET 8 that is connected to the main MOSFET in parallel and detects a current shunted from a current of the main MOSFET. The main MOSFET is formed using a multi-finger MOSFET that has a plurality of channels and is arranged in a row. When a distance between the center of the multi-finger MOSFET 7 and a channel located farthest from the center of the multi-finger MOSFET 7 is indicated by L, a channel that is located closest to a position distant by a distance of (L/(?3)) from the center of the multi-finger MOSFET is used as a channel for the sense MOSFET 8.

Abstract: A two-level two-terminal modular multilevel converter subsystem. The subsystem includes a first capacitor and a second capacitor. The modular multilevel converter subsystem is configured to selectively place the first capacitor in series with the second capacitor. The modular multilevel converter subsystem is also configured to selectively place the first capacitor in parallel with the second capacitor relative to first and second output terminals of the modular multilevel converter subsystem.

Abstract: Disclosed is a power conversion device which achieves reductions in switching loss due to a reverse recovery current and heat generation loss. Specifically disclosed is a power conversion device provided with a cascode element configured by electrically connecting a normally-on switching element and a normally-off switching element in series and connecting a gate terminal of the normally-on switching element and a source terminal of the normally-off switching element via a cascode connection diode, and a high-speed diode electrically connected in parallel with the cascode element and having a cathode region connected to a positive electrode terminal and an anode region connected to a negative electrode terminal.

Abstract: A power generator includes one or more full bridge inverter modules coupled to a semiconductor opening switch (SOS) through an inductive resonant branch. Each module includes a plurality of switches that are switched in a fashion causing the one or more full bridge inverter modules to drive the semiconductor opening switch SOS through the resonant circuit to generate pulses to a load connected in parallel with the SOS.

Abstract: A multilevel inverter includes an inverter arm. The inverter arm is provided between a highest electric potential point and a lowest electric potential point, and includes (i) a second switching element group to which switching elements that are connected in series belong, the switching elements being connected to respective diodes which are connected in an opposite polarity and in parallel and (ii) a diode for each power supply connection point. One of connection points at which the switching elements belonging to the second switching element group are connected to each other and a U phase output terminal are connected, the one connection point being located such that at least one of the switching elements provided between the one connection point and the highest electric potential point is equal in number to the other switching elements which belong to the second switching element group and are provided between the one connection point and the lowest electric potential point.

Abstract: A control device (701) for controlling the output of one or more full-bridges (101, 102) is described. The control device (701) reduces the amount of electromagnetic emissions by staggering the switching the outputs from the full-bridge inverters (101, 102). This is achieved by synchronizing the outputs to be symmetrical about a synchronization pulse (305).

Abstract: Systems, methods, and circuits for providing zero voltage switching conditions across all load conditions in a full-bridge DC/DC converter. An asymmetric auxiliary circuit is provided and the reactive current due to the auxiliary circuit is controlled across various load conditions. This is done by adaptively adjusting the switching frequency of the converter as well as the phase shift of the rising edges of the waveforms for activating the gates in the leading and lagging legs of the full bridge converter.

Abstract: The invention relates to a control method applicable to structures for converting direct current/alternating current, dc/ac, especially for photovoltaic systems. The control method according to the invention enables the switching losses of the semiconductors to be reduced, thereby improving the efficiency of the conversion structure. The invention can also be applied to other fields of energy, such as the generation of energy by means of electrochemical cells or wind energy.

Abstract: A power module includes a substrate including an insulating member and a patterned metallization on the insulating member. The patterned metallization is segmented into a plurality of spaced apart metallization regions. Adjacent ones of the metallization regions are separated by a groove which extends through the patterned metallization to the insulating member. A first power transistor circuit includes a first power switch attached to a first one of the metallization regions and a second power switch attached to a second one of the metallization regions adjacent a first side of the first metallization region. A second power transistor circuit includes a third power switch attached to the first metallization region and a fourth power switch attached to a third one of the metallization regions adjacent a second side of the first metallization region which opposes the first side. The second power transistor circuit mirrors the first power transistor circuit.

Abstract: A current-fed full-bridge DC-DC converter includes a current source circuit including a direct-current voltage source circuit and a reactor connected to the direct-current voltage source circuit in series, an inverter circuit including switching elements, input terminals and output terminals, wherein outputs of the current source circuit are connected to the input terminals, a transformer having a primary coil that is connected to the output terminals and a secondary coil and a rectifier circuit which is connected to the secondary coil and through which the current-fed full-bridge DC-DC converter generates direct-current output. The current-fed full-bridge DC-DC converter further includes a capacitor connected to the output terminal and the primary coil in series and a controller controlling on/off operations of the switching elements so that a current can flow from the current source circuit through the primary coil and the capacitor in stopping of the current-fed full-bridge DC-DC converter.

Abstract: A grid-connected inverter for feeding current via a transformer into an electric power grid includes an output bridge arrangement that is actuated via a pulse width modulator, wherein a periodic auxiliary signal is used to determine switching times of the output bridge arrangement. The inverter also includes a synchronization unit for phase synchronization of the auxiliary signal with the electric power grid, wherein the synchronization unit is configured to set a predetermined phase offset (??0) of the periodic auxiliary signal with respect to a phase of the electric power grid.

Abstract: A switching power supply apparatus includes a low-side switching control unit and a high-side switching control unit. The low-side switching control unit includes a low-side turn-off circuit that turns off a low-side switching element behind a delay time when reversal of the polarity of a winding voltage of a transformer is detected during a period in which a drive voltage signal is supplied to the low-side switching element. The high-side switching control unit includes a high-side turn-on delay circuit that delays a time from the time when the polarity of the winding voltage of the transformer is reversed to a time when a high-side switching element is turned on. The delay time of the low-side turn-off delay circuit is set so as to be shorter than the delay time of the high-side turn-on delay circuit.

Abstract: A neutral point clamped three-phase three-level inverter is connected to a first DC power supply and single-phase inverters are connected in series with AC output lines of individual phases of the three-phase three-level inverter such that sums of output voltages of the three-phase three-level inverter and output voltages of the respective single-phase inverters are output to a load through a smoothing filter. An output control unit controls the three-phase three-level inverter so that the individual phases of the three-phase three-level inverter output primary voltage pulses at a rate of one pulse per half cycle and controls the individual single-phase inverters by PWM, so that output voltages to the individual phases of the load form sine waves of which phases are offset by 2?/3 from one phase to another, the sine waves having the same peak value.

Abstract: An inverter control is used to control the output of a distributed power generating station, such as a photovoltaic (PV) solar power station, connected to a power grid. The power station is connected to an inverter output. Pulse width modulation is used to shape the output in order to maximize power output within power quality parameters and provides control of a switching frequency of the inverter responsive to a sensed parameter. The technique allows an increase in output efficiency and provides for adjustment of power output to meet power quality parameters to an extent required in order to connect to the power grid.

Abstract: A switching control IC conducts on-off control on a first switching element. A second switching control circuit is provided between a high-side driving winding of a transformer T and a second switching element. The second switching control circuit discharges a capacitor in a negative direction with a constant current during an on period of the first switching element, and then after the second switching element is turned on, charges the capacitor in a positive direction with a constant current. A transistor controls the on period of the second switching element in accordance with the ratio of a charging current to a discharge current such that the ratio of the on period of the second switching element to the on period of the first switching element is substantially always constant.

Abstract: A control section which repeats inverter control in units of an inverter control period having a predetermined length is provided. In the control section, a phase current detection period in which a phase current is detected is provided between predetermined two inverter control periods, each of switching states of switching elements of a inverter circuit is controlled so that a voltage pulse having a larger width than a width of a voltage pulse in the inverter control period is output from a shunt resistor in the phase current detection period.

Abstract: Disclosed are an apparatus and a method for photovoltaic power generation according to the exemplary embodiment of the present disclosure configured to enhance efficiency of photovoltaic power generation, wherein the apparatus having a solar module, a booster and an inverter includes a voltage sensing unit configured to sense an output voltage of the solar module, a switching unit connected to the booster in parallel, and a controller configured to selectively control the booster or the switching unit whereby the booster or the switching unit can be driven in response to an output voltage level sensed by the voltage sensing unit.

Abstract: A detecting device detects the midpoint voltage of a half bridge circuit of transistors. The circuit comprises a bootstrap capacitor having one terminal connected to the midpoint node of the half bridge circuit and another terminal connected to a supply circuit. The device comprises a further capacitor connected between a second terminal of the bootstrap capacitor and circuit means adapted to form a low impedance node for a current signal circulating in said further capacitor during the transitions from the low value to the high value and from the high value to the low value of the midpoint voltage. The device comprises a detector to detect said current signal circulating in said further capacitor and to output at least a first signal indicating the transitions from the low value to the high value or from the high value to the low value according to said current signal.

Abstract: A control system controls a multiphase rotating machine by a 120° energization process and a PWM process. In the 120° energization process, respective ones of switching elements of a high side arm and switching elements of a low side arm of a power conversion circuit are turned on. In the PWM process, the switching elements of the power conversion circuit turn on/off so that two phases that are connected to the switching elements that are in the on-state are alternately rendered conductive to the high potential side input terminal and the low potential side input terminal of the power conversion circuit.

Abstract: A method and a device for operating a bridge power supply circuit comprising at least two switch members connected in series between two rails and operated alternatingly to provide a pulse width modulated output signal at a junction between the two transistors. A measurement circuit measures a voltage drop over the lower switch member during conduction of said switch member. The measurement is performed approximately in the middle of the ON-period and is used in the next cycle for calculating the timing signals. A control signal (Ucontrol) is received at an input for the pulse width modulated output signal. The measured voltage drop is added to the control signal before calculating the timing signals. The voltage drop is scaled by a scaling factor of for example 0.8 before being added to the control signal.

Abstract: A DC/DC converter for converting an input DC voltage between input lines into an output DC voltage between output lines includes: an AC current forward path connected via switching electric components to at least one of the output lines and at least one of the output lines; an AC current backflow path connected via same electric connections to at least one of the input lines and at least one of the output lines; and an auxiliary converter for compensating a sum of currents flowing via all forward and backflow paths, the auxiliary converter connecting one end of an compensation current path via two pulsed switches alternately to two lines at one side, the other end of the compensation path being connected to at least one line at the other side of the converter. The input lines are galvanically separated from the output lines by capacitances in all current paths.

Abstract: A Dual Active Bridge (DAB) converter and a Pulse Width Modulation (PWM) scheme for controlling the DAB converter are disclosed. In general, the DAB converter includes a transformer, a first H-bridge that is connected to a primary winding of the transformer and controlled via first control signals, and a second H-bridge that is connected to a secondary winding of the transformer and controlled via second control signals. A controller provides the first and second control signals based on an input-to-output voltage ratio and load of the DAB converter such that, in addition to phase shift control, PWM control is simultaneously applied to both the first H-bridge and the second H-bridge when the DAB converter operates at low power and PWM control is applied to only one of the first H-bridge and the second H-bridge when the DAB converter operates above low power.

Abstract: To make it possible to avoid an unstable state with a simple configuration even one of the phases of the motor fails. A motor drive system in accordance with the present invention includes a motor to which a plurality of phase coils of five phases or more are connected in a star connection, an inverter connected to one end of each of the phase coils, the inverter being configured to convert a DC power into an AC power and supply the AC power to each phase of the motor, a power relay disposed at another end of each of the phase coils, the power relay being configured so as to be able to cut off a supply power to at least one phase coil among the plurality of phase coils of the motor by using a plurality of contact points interposed between the star-connected coils, and a control unit that generates a control signal for the inverter and thereby controls driving of the motor.

Abstract: Various embodiments of the present invention provide voltage converters and methods for using such. As one example, a voltage converter is disclosed that includes a transformer with a first winding and a second winding. A voltage is applied to the first winding for a period that is followed by an OFF time. The voltage converter further includes an OFF time controller that is operable to adjust the OFF time based at least in part on a load current traversing the second winding.

Abstract: A circuit, device, and method for controlling a buck-boost circuit includes a bootstrap capacitor voltage regulator circuit and a comparator circuit. The bootstrap capacitor voltage regulator circuit is electrically coupled to a buck-mode bootstrap capacitor of the buck-boost converter and to a boost-mode bootstrap capacitor of the buck-boost converter. The comparator circuit is configured to control the bootstrap capacitor voltage regulator circuit to maintain a voltage of the bootstrap capacitors above a reference threshold voltage by transferring an amount energy from one of the bootstrap capacitors to the other bootstrap capacitors based on the particular mode of operation of the buck-boost converter.

Abstract: A power conditioner that suppresses generation of voltage spikes in a part of a generated sinusoidal voltage waveform. An offset between the timing of chopping, which depends on whether the voltage difference between the voltage of a third pulse voltage series and a sinusoidal voltage is positive or negative, and the timing of the switching between on/off duty cycles of a seventh and eighth switch is calculated, and the on/off duty cycles of the seventh and eighth switches are controlled on the basis of the timing offset.

Abstract: Provided is an apparatus for controlling an inverter current, and more particularly, to a current controlling apparatus for controlling current of a switching element of an inverter that outputs a 3-phase alternating current. The apparatus for controlling an inverter current includes: an inverter comprising a plurality of current detection switching elements capable of detecting switched and output current, converting a direct current voltage into a 3-phase alternating current by turning the plurality of current detection switching elements on and off; an AD converter for directly receiving an input of an output current of an output terminal of each of the plurality of current detection switching elements as a detection current and converting the detection current into a detection signal value in digital form; and a control unit for controlling on and off of the plurality of current detection switching elements by using the detection signal value.

Abstract: In a semiconductor module, a high-potential side conductor includes a wide section on which the high-potential side switching element is mounted, a high-potential side terminal coupled with a high potential source, and a narrow section extending from the wide section to the high-potential side terminal in a first direction. The wide section is wider than the narrow section in a second direction perpendicular to the first direction. The wide section has a first side and a second side opposite to the first side in the second direction. A distance between the first side of the wide section and a low-potential side conductor is shorter than a distance between the second side of the wide section and the low-potential side conductor. The narrow section extends from a portion of the wide section closer to the first side than the second side.

Abstract: A method is for controlling a three-phase current converter. First, subtract a second reference current signal representing the predicted current of the three-phase terminals in the present switching cycle from a first reference current signal representing the predicted current of the three-phase terminals in the next switching cycle to obtain a predicted variation. Then, subtract a feedback current signal representing the feedback current of the three-phase terminals in the previous switching cycle from the second reference current signal delayed by one switching cycle to obtain a current error. Multiply the current error by an error coefficient then add the predicted variation to obtain a current variation. Finally, obtain duty ratios of a plurality of switches, according to the current variation and inductance of the first to the third inductor. The three-phase current converter converts electric power between a DC terminal and the three-phase terminals, according to the duty ratio.

Abstract: An inverter control device drives one of the two switching circuits with a fixed conduction width and changes the control method of the other switching circuit between pulse-width modulation, phase control method, and drive signal width control method by phase control method according to an output state, to implement highly accurate control at low output while suppressing heat generation of a switching element.

Abstract: A control system for an AC motor determines a slope Ktl of a tangent TL at an operating point Pa corresponding to the current motor operating state and voltage phase (?0) on a torque characteristic curve that is plotted according to a torque equation representing an output torque characteristic with respect to the motor operating state and the voltage phase of the rectangular wave voltage. The control system further calculates a voltage phase change amount ?ff for use in feed-forward control, according to ?Ttl/Ktl obtained by dividing a torque compensation amount ?Ttl for feed-forward control by the slope Ktl.

Abstract: A power converting apparatus comprises a DC-DC converter circuit that steps up or steps down an input voltage from a DC power supply, a DC-AC converter circuit that converts an intermediate voltage outputted by the DC-DC converter circuit to an alternate current, and a control circuit that controls the DC-DC converter circuit and the DC-AC converter circuit. The control circuit is provided with a circuit control unit that controls the DC-DC converter circuit so that the modulation factor, which is the amplitude ratio between a signal wave for manipulating the DC-AC converter circuit and the carrier wave therefor, will become a target modulation factor.

Abstract: A converter system comprises a DC to AC converter, a maximum power point tracking device, and an array-side control. The DC link converts DC from a photovoltaic array to AC for a grid. The maximum power point tracking device is coupled to the array. The array-side control, which is coupled to the DC to AC converter and the device, prevents overvoltage in the DC bus of the DC to AC converter using array voltage and current data from the device and DC bus voltage data from the DC to AC converter during a grid transient by adjusting a maximum power point of the array to increase array voltage.

Abstract: A voltage source converter station including a multilevel voltage source converter, for conversion of electrical power between AC and DC, and a control system. The voltage source converter includes a plurality of switching cells including switchable semiconductors, and the control system includes at least one main control unit for providing a voltage reference signal and a plurality of cell control units. Each cell control unit uses carrier based pulse width modulation for controlling the switching of a respective cell, where the main control unit is communicatively connected to the cell control units and provides the reference voltage signal to each cell control unit and each cell control unit creates a switching signal to each respective switching cell using the reference voltage signal and a carrier signal to effectuate the conversion.

Abstract: A method of balancing current in a vehicle electric system having a system bus, a first battery, a first bi-directional battery voltage converter selectively transferring a first current between the first battery and the system bus, a second battery, a second bi-directional battery voltage converter selectively transferring a second current between the second battery and the system bus, and a controller controlling the first bi-directional battery voltage converter and the second bi-directional battery voltage converter. The method includes sensing the first current and sensing the second current. The first bi-directional battery voltage converter and the second bi-directional battery voltage converter are controlled so that the first current and the second current are equal portions of a load current supplied to an electrical load connected to the system bus.

Abstract: A power conditioner of a photovoltaic system is configured operate at higher accuracy. A chopper circuit, a capacitor connected in parallel to the chopper circuit, and a control circuit that controls an ON/OFF status of switch elements in the chopper circuit to control charging and discharging of the capacitor are provided. The control circuit includes a measurement control section that measures an inter-end voltage of the capacitor and a control circuit section that performs a predetermined control operation from a measurement output of the measurement circuit section. The measurement circuit section includes a differential amplifier circuit that differentially amplifies the inter-end voltage of the capacitor. The circuit control section calibrates an in-phase component in the output of the differential amplifier circuit as an in-phase error and performs the control from the calibrated output from the differential amplifier circuit.

Abstract: A power converter system includes a converter configured to be coupled to a power generation unit for receiving power from the power generation unit, and a bus coupled to the converter, wherein a voltage is generated across the bus when electricity is conducted through the power converter system. The power converter system also includes an inverter coupled to the bus and configured to supply power to an electrical distribution network, and a control system coupled to the converter and to the inverter. The control system is configured to gradually adjust the voltage across the bus during at least one of a shutdown sequence and a startup sequence of the power converter system.

Abstract: A control apparatus and a control method for an AC electric motor detect DC bus current plural times at predetermined intervals during first and second predetermined periods and multiply vectors having integrated values of detected values during respective periods as elements by an inverse matrix of a matrix having integrated values during respective periods of sine and cosine functions of output voltage phase of an inverter at the moment that detection is made as elements to thereby estimate reactive and active currents.

Abstract: The present invention relates to a DC to AC inverter comprising a plurality of voltage controlled switching devices, where one or more of the voltage controlled switching devices is driven by a drive circuit comprising: a bridge switching circuit (59), a transformer (28) with a primary winding (29) and a secondary-winding (30), a transition selection circuit (60) coupled to a control terminal of a respective voltage controlled switching device (40) of the inverter, at least one inductance (37) that forms at least one resonant circuit with the input capacitance (41) of the control terminal, wherein the bridge switching circuit (59) can be operated to generate drive pulses via the selection circuit (60) to operate the respective voltage controlled switching device (40).

Abstract: A power converter employing a controller configured to increase a dead time between conduction periods of first and second power switches therein and method of operating the same. In one embodiment, the power converter includes first and second power switches coupled to an input thereof, and a sensor configured to provide a sensed signal representative of at least one of a current level and a power level of the power converter. The power converter also includes a controller configured to increase a dead time between conduction periods of the first and second power switches when the sensed signal indicates a decrease of at least one of the current level and the power level of the power converter.

Abstract: A current controlled power converter includes a converting part configured to convert a three-phase ac voltage into a dc voltage or converts a dc voltage into a three-phase ac voltage, ac side current detection portions configured to detect an ac side current of the converting part, dc side current detection portions configured to detect a dc side current of the converting part, and a control section configured to control the converting part by pulse-width modulation using a spatial vector modulation method based on the ac side current detected by the ac side current detection portions and the dc side current detected by the dc side current detection portions. The control section corrects an amplitude error of the ac side current detected by the ac side current detection portions, and an offset error of the ac side current detected by the ac side current detection portions.

Abstract: A power detection regulation device including a power detection signal generator, a power state detector and a regulated output unit is disclosed. The power detection signal generator receives the input power from an external power supply and generates a power detection signal. The power state detector generates a power state signal based on the power state derived from the power detection signal. The regulated output unit receives the power state signal and generates a driving signal to an external electrical device in accordance with the feedback signal from the external electrical device. The power state signal is provided for the external electrical element to perform relevant processes, and the regulated output device can output the predetermined driving signal on receiving the power state signal indicating some abnormal situation in the input power so as to maintain the normal operation performed by the actuating element in the external electrical device.

Abstract: A power conversion apparatus includes a current sensor that detects a phase current flowing through a phase current line, a first phase-voltage detection unit that detects a first phase voltage in the phase current line with a potential in a P line as a reference, a second phase-voltage detection unit that detects a second phase voltage in the phase current line with a potential in an N line as a reference, an estimation unit that estimates a zero-cross point timing of the phase current based on magnitude and symbol of the first and second phase voltage, a calculation unit that obtains a correction value with respect to a detection value of the current sensor according to the detection value of the current sensor at the estimated zero-cross point timing, and a correction unit that corrects a detection value of the current sensor by using the obtained correction value.

Abstract: Power conversion methods, systems, articles of manufacture, and devices are provided. The power conversion may include converting between direct current and alternating current wherein switching losses associated with latent electrical charges are reduced. Current sensing may be low-side bus reference. Solid-state implementations, code implementations, and mixed implementations are provided.

Abstract: A bipolar pulsed power supply which supplies power in a bipolar pulsed mode at a predetermined frequency to a pair of electrodes that come into contact with a plasma is arranged to reduce the switching loss of the switching elements in a bridge circuit, and also to attain a high durability without using high-performance switching elements. The bipolar pulsed power supply has: a bridge circuit constituted by switching elements SW1 through SW4 connected to positive and negative DC outputs from a DC power supply source; and a control means for controlling switching ON or OFF of each of the switching elements in the bridge circuit. An output-short-circuiting switching element SW0 is disposed between the positive and the negative DC outputs from the DC power supply source such that, in a short-circuited state of the output-short-circuiting switching element, each of the switching elements in the bridge circuit is switched by the control means.

Abstract: A power conversion apparatus includes two power conversion circuits, two direct-current inductors, and a pulse-width-modulation control circuit. One of the two power conversion circuits is connected in parallel to a direct-current load or a single-phase alternating-current load, and the other of the two power conversion circuits is connected in parallel to a three-phase alternating-current load. The two power conversion circuits are connected in reverse polarity to each other via the two direct-current inductors. The pulse-width-modulation control circuit pulse-width-modulates the two power conversion circuits, allows switching between the two power conversion circuits, and realizes a bidirectional step-up/down operation between the direct-current load or single-phase alternating-current load and the three-phase alternating-current load.

Abstract: A method and an arrangement of measuring inverter current, where the inverter is connected to and supplied by a DC intermediate circuit having two or more parallel capacitor branches connected between the positive and negative rail of the DC intermediate circuit, and the capacitance of the capacitor branches being known. The method comprises the steps of measuring the current of one of the parallel capacitor branches, and determining from the measured current the magnitude of the inverter current.

Abstract: Power supplies, power adapters, and related methods are disclosed. One example power supply includes an open loop DC to DC converter having an input for connecting to an input power source and an output for supplying a DC output voltage or current and an enable/disable circuit coupled to the open loop DC to DC converter. The enable/disable circuit is configured to enable and disable the open loop DC to DC converter as a function of the DC output voltage or current. One example method includes determining a DC output voltage or current from an open loop DC to DC converter and enabling and disabling the open loop DC to DC converter as a function of the determined DC output voltage or current.

Abstract: The present invention is a single-phase voltage source DC-AC power converter and a three-phase voltage source DC-AC power converter.

Abstract: A device (1) for feeding electrical energy from an energy source with variable source voltage into an electric power supply network (15), said device (1) including a transformer (112) for galvanic isolation, a resonant inverter (11) with semi-conductor switches (a-d; A, B), one or several resonant capacitors (17; 18, 19; 20, 21) and one rectifier (113), is intended to provide high efficiency and have galvanic isolation. This is achieved in that the resonant inverter (11) is operated in the full resonant mode if the operating voltage is in an operation point (MPP) and in the hard-switching mode if the voltages exceed the operation point (MPP).