A two-wheeled inverted pendulum vehicle includes: single-winding first and second motors respectively rotating one of two wheels; first and second control systems respectively supplying drive currents to the first and second motors; a sensor detecting a physical quantity that varies with a turn of the vehicle; a dynamic brake unit being able to switch between active and inactive states of dynamic brake being applied to the first motor; and a control unit, when the control unit has determined that the vehicle is turning about the second motor side on the basis of the physical quantity while supply of drive current from the first control system to the first motor is inhibited, activating dynamic brake in the dynamic brake unit. The first control system, when an abnormality has been detected in the first control system, inhibits supply of drive current from the first control system to the first motor.

A cleaning system for a combine harvester that includes a cleaning shoe having a sieve, a cleaning fan, an air plenum and a pair of air diverters is provided. The cleaning fan is rotatably driven for generating a flow of air and positioned within the air plenum. The air plenum extends across the entire length of the cleaning fan and includes an inlet for the intake of air, an outlet downstream the inlet for directing the flow of air in a first direction, lateral walls forming a portion of the outlet, and a bottom wall extending between the lateral walls. The pair of air diverters extends inwardly from the lateral walls. Each air diverter is configured substantially as a pyramid having a rounded corner that extends inwardly from the lateral wall and upwardly from the bottom wall.

An inverted pendulum type vehicle (1) includes a propulsion unit (50) provided in a lower part of a vehicle body to actuate a main wheel (52), a drive unit (90, 130) provided in a vertically intermediate part thereof and a seat (200) provided in an upper part of the vehicle body. A battery case (251) is mounted in a part of the vehicle body above the main wheel and behind the drive unit. The battery case is provided with an opening (257) extending from an upper part thereof to a lower end of a rear part thereof. A lid (260) hinged to the battery case selectively covers the upper end of a battery (250) received in the battery case. The battery is retained in the battery case with the help of suitable engagement arrangements (262, 263, 270, 271, 273, 274).

An axle assembly having a carrier housing, a pair of axle tubes, a differential case, a pair of differential bearings and a pair of bearing adjusters. The carrier housing includes a cavity, which is configured to receive the differential case, and a pair of axle tubes that are mounted to the carrier housing. The differential case includes bearing bores into which the outer races of the differential bearings are received. The bearing adjusters are threaded to the carrier housing and support the differential bearings on a side opposite the differential case.

A paver for laying down a strip of concrete and inserting therein dowel bars parallel to the strip. A dowel bar inserter orients the bars and places them into the concrete. A pair of transport chains transverse to the travel direction extends across a width of the inserter. Pairs of generally L-shaped opposing cups hold the bars so that they can drop downwardly from the cups towards the strip. The chains move in a single direction. A dowel bar holding magazine, above the chains, stores bars, and gravitationally moves the bars towards the chains for pick-up by cups as the chains move the cups past a bar loading station. Elastic bands extend about a bar engaging surface defined by a wheel and resiliently bias the bars moving along the chain turn-around section against the wheel.

A system for treating heart disease, such as pulmonary hypertension or right heart failure, including an implantable component and external components for monitoring the implantable component is provided. The implantable component may include a compliant member, e.g., balloon, coupled to a reservoir via a conduit. Preferably, the compliant member is adapted to be implanted in a pulmonary artery and the reservoir is adapted to be implanted subcutaneously. The external components may include a clinical controller component, monitoring software configured to run a clinician's computer, a patient monitoring device, and a mobile application configured to run on a patient's mobile device.

An elongate inserter has a distal end releasably connected to an expandable interbody fusion device and a proximal end including a trigger actuator. The interbody fusion device comprises a superior endplate and an inferior endplate that are movable in an expansion direction relative to each other in the intradiscal space. The inserter includes a lifting platform and an elevator that define cooperatively engaging ramps and ramps surfaces that upon operation of the trigger actuator cause the superior and inferior endplates to move relatively away from each other. A driver is supported by the inserter for pushing an insert into the expanded device between the superior and inferior endplates.

An intervertebral fusion cage that is adapted to contain an inserter within its inner volume during insertion of the cage.

Various embodiments of intervertebral implants, anchoring devices for intervertebral implants, and implantation instrumentation are provided, along with various embodiments of methods for using one or more of the devices. Some embodiments of an anchoring device have a body comprising at least one curve and a rigid plate elongated along a longitudinal axis so that its front end enters at least one vertebra while its rear end remains in the passage of an implant. In some embodiments, the plate comprises at least one longitudinal slot separating at least one posterior portion of the plate into two branches, with at least one branch comprising at least one withdrawal stop configured to retain the device in the implant.

The present disclosure relates to a suture anchor inserter. The suture anchor inserter includes a handle having a proximal component, a central component coupled to the proximal component, and a distal component coupled to the proximal component and the central component, the central component capable of rotating relative to the proximal component; and a shaft comprising a proximal end and a distal end, the proximal end coupled to the handle. A method of inserting a suture anchor into bone is also disclosed.

An apparatus for insertion of a medical device in the skin of a subject is provided, as well as methods of inserting medical devices.

A prosthetic inserter includes an inserter head having at least first and second bosses, at least one of the bosses movable from a first position to a second position, that couple the inserter to a femoral provisional component via a pair of corresponding apertures, such as drill holes, within the articulating surfaces of a selected one of a series of femoral provisional components. Each provisional component of the series is capable of having different aperture distances measured between a respective pair of apertures. The bosses of the inserter are biased into an engagement position in which the inserter can be secured to a femoral provisional component to eliminate the need for an external engagement force to be supplied to the inserter.

A boost converter with a multiple input and with improved efficiency has two or more inputs. A DC voltage source can be connected to each input. A common output carries a DC voltage whose value is greater than or equal to that of the input voltages. The common output is in each case connected to each of the plurality of inputs via a positive lead branch and a negative lead branch. At least one inductor is arranged in the positive lead branch and/or the negative lead branch from each input, and at least one rectification element is arranged in the positive lead branch and/or the negative lead branch from each input. Furthermore, the inputs can be connected in series by means of two or more switching elements via the inductors, wherein at least two of the inductors can in each case be connected in parallel.

An inverter circuit contains a first and second DC sources for providing a DC voltage, a common step-up converter for boosting the DC voltage, an intermediate circuit capacitor connected between the outputs of the common step-up converter, and an inverter for converting the DC voltage provided by the capacitor into an AC voltage. The common step-up converter contains a series circuit having a first inductance and a first rectifier element and is connected between an output of the first DC source and one side of the intermediate circuit capacitor as well as a series circuit which includes a second inductance and a second rectifier element and is connected between an output of the second DC source and another side of the intermediate circuit capacitor. The common step-up converter further contains a common switching element which is connected between the first and second DC sources.

A converter power unit comprises: a heat sink; n power switch modules on the heat sink; a first group of laminated bus bars comprising a first and a second bus bar; a capacitor group comprising m capacitor; a second group of laminated bus bars comprising a third and a fourth bus bar, the first bus bar is connected with the third bus bar, the second bus bar is connected with the fourth bus bar; providing that vertical projection areas projected by an area occupied by the n power switch modules and projected by the capacitor group on a first plane perpendicular to an axial direction of the capacitor group are defined as a first and a second projection areas respectively, the first and the second projection area have an overlapped area. The present application can reduce the stray inductances in the commutating loop of the converter.

A power inverter includes a power semiconductor module that includes a power semiconductor device, a control circuit board that outputs a control signal used for controlling the power semiconductor device, a driver circuit board that outputs a driving signal used for driving the power semiconductor device, a conductive metal base plate arranged in a space between the driver circuit board and the control circuit board in which a fine and long opening portion is formed, wiring that connects the driver circuit board and the control circuit board through the opening portion and delivers the control signal to the driver circuit board, and an AC busbar that is arranged on a side opposite to the metal base plate through the driver circuit board and delivers an AC current output from the power semiconductor module to a drive motor. At least a portion of the AC busbar that faces the opening portion extends in a direction directly running in a longitudinal direction of the fine and long opening portion.

The invention provides a laser converter for converting a laser radiation of shorter wavelength to a laser radiation of longer wavelength using a single stage conversion. The laser converter comprises a laser diode for emitting a laser radiation in a first wavelength range, a cylindrical microlens for transferring and focusing the laser radiation to a laser chip and the laser chip for absorbing the laser radiation and emitting the laser radiation in a second wavelength range.

A counter includes a buffer unit and a ripple counter. The buffer unit generates at least one least significant signal of a count by buffering at least one clock signal until a termination time point. The ripple counter generates at least one most significant signal of the count by sequentially toggling in response to at least one of the least significant signal. The counter performs multiple data rate counting with enhance operation speed and reduced power consumption.

A counter configured to perform counting at both edges of an input clock to output an additional value or a subtraction value for a previous count value and a next count value includes a first latch circuit that latches the input clock, a second latch circuit that latches an output from the first latch circuit, a holding section that holds data of the 0th bit of a count value, and a correction section that performs count correction on data of the first and subsequent bits of the count value on the basis of an output of the second latch circuit.

A system for lifting a vehicle via multiple slings comprises a vehicle not engineered with structural facility to withstand lifting forces, including a frame which unmodified will deform in response to vertically imposed lifting forces, frame reinforcing elements affixed to the frame at selected locations which are subject to lifting deformation, at least two lifting members at spaced-apart forward frame locations, at least two lifting members at spaced-apart rearward frame locations, and a plurality of elongate slings extending respectively between each lifting member and a common lifting vertex. Each lifting member has an enlarged lower base portion rigidly affixed to the frame and an upper lifting portion. The frame reinforcing elements resist deformation of the frame in response to vertically imposed lifting forces. The enlarged base portions of the lifting members apply forces over a correspondingly enlarged area of the frame and the reinforcing elements without deforming the frame.

A digital phase locked loop (DPLL), a method of operating the same, and a device including the same are provided. The DPLL includes a digitally-controlled oscillator configured to change a frequency and a phase of an output oscillation signal in response to a digital control code; a main divider configured to divide the frequency of the output oscillation signal and generate a first feedback signal based on the divided frequency; and a phase-to-digital converter configured to subdivide the phase of the output oscillation signal and to generate a quantized code by converting a phase difference between a reference signal and the first feedback signal using a phase-subdivided signal resulting from the subdivision. The digital control code is generated based on the quantized code.

A solar power inverter having a sealing means includes: a main case having an opening on a front surface thereof, the opening open and closed by a main cover; an auxiliary case coupled to one side surface of the main case, and having a second opening on a front surface thereof, the second opening open and closed by an auxiliary cover; and a gasket interposed between the main case and the auxiliary case, wherein the main case and the auxiliary case are coupled to each other by coupling bolts which pass through the main case, the gasket and the auxiliary case.

A power converter is configured to include an inverter which converts a DC output into an AC voltage of a predetermined frequency, and a high voltage generator which receives an output from output terminals of the inverter and boosts the output to a desired high DC voltage. The high voltage generator includes a transformer, and the primary windings of the transformer are connected to the output terminals of the inverter in parallel by conductive wires connected to both ends of each primary winding. Further, a current sensor is provided to detect a current flowing through each of the primary windings, and a control unit determines abnormalities of a path of the inverter and the primary windings on the basis of a value of the current sensor.

An inverter generator used in combination with a motor and an ECU generating a pulse at each predetermined rotation angle of the motor is comprised of: an electric generator driven by the motor configured to generate alternating current electric power; estimating means for estimating an electrical angle of alternating voltage of the alternating current electric power from the pulse, the estimating means being electrically connected with the ECU; a converter configured to convert the alternating current electric power into direct current electric power, the converter electrically connected with the electric generator and the estimating means; and an inverter configured to convert the direct current electric power into alternating current output electric power, the inverter electrically connected with the converter.

A generator system includes a generator having a stationary portion and a rotating portion. An exciter field winding and a main armature winding are disposed on the stationary portion. An exciter armature winding and a main field winding are disposed on the rotating portion. A frequency demodulator is configured to extract a frequency modulated control signal from the exciter armature winding and to demodulate the frequency modulated control signal to generate a demodulated control signal. The generator includes a main field rotating power converter to selectively control current in the main field winding in response to the demodulated command signal. The generator system includes a generator control unit in electrical communication with the generator to monitor the output voltage at the main armature winding and to output an exciter current including the frequency modulated control signal to the exciter field winding based on the output voltage.

A method of operating a converter of a wind turbine for providing electric energy to a utility grid includes determining a grid voltage. If the grid voltage is between a nominal voltage and a first voltage threshold, i.e. higher than the nominal voltage, a normal procedure for lowering the grid voltage is performed. If the grid voltage is above the first voltage threshold, another procedure for keeping the wind turbine connected is performed, wherein the other procedure is different from the normal procedure. Further a corresponding arrangement is described.

Systems and methods for reducing current imbalance between parallel bridge circuits used in a power converter of a doubly fed induction generator (DFIG) system are provided. A control system can monitor the bridge current of each of the bridge circuits coupled in parallel and generate a feedback signal indicative of the difference in bridge current between the parallel bridge circuits. Command signals for controlling the bridge circuits can then be developed based on the feedback signal to reduce current imbalance between the bridge circuits. For instance, the pulse width modulation of switching devices (e.g. IGBTs) used in the bridge circuits can be modified to reduce current imbalance between the parallel bridge circuits.

A double fed induction generator (DFIG) converter method are presented in which rotor side current spikes are attenuated using series-connected damping resistance in response to grid fault occurrences or grid fault clearances.

A DC voltage converter includes an oscillator that converts a DC battery voltage to an oscillating voltage, a low voltage transformer that increases the oscillating voltage to a higher oscillating voltage, and a voltage rectifying-capacitor charging network or multiplier that increases the higher oscillating voltage to yet a higher DC voltage at an output terminal for DC high voltage utilization devices and the like. An electric control switch is selectively actuated by the user to apply the battery voltage to the oscillator, resulting in the generation of the stepped-up DC voltage at an output terminal. Another DC voltage converter has an electronic switching circuit that automatically turns the oscillator on and off and a load capacitor across the electrodes that is charged and discharged to provide a shocking voltage. Utilization devices for the voltage developed by the converter shown are a miniature animal training device and a cattle prod device. The miniature animal training device has a pair of outwardly projecting electrodes mounted on a side at one end of the housing that is sized and shaped to fit within and conform to the palm of a hand. The cattle prod device has a pair of electrodes fixedly mounted on the end of a housing assembly made up of telescoping tubular housing sections arranged for relative axial movement whereby the pressing of the electrodes against an object to be shocked actuates the electric control switch and causes a shock of the object. The housing assembly is releasably supported by a rigid handle or an extensible handle assembly.

A sensor includes a collector, an emitter and a base-region barrier formed as an inverted bipolar junction transistor having a base substrate forming a base electrode to activate the inverted bipolar junction transistor. A level surface is formed by the collector, the emitter and the base-region barrier opposite the base substrate such that when the level surface is exposed to charge, the charge is measured during operation of the bipolar junction transistor.

Provided is an A/D converter including an input terminal, a reference signal line for supplying a reference signal which changes temporally, a comparator, a correction capacitor connected to an inverting input terminal of the comparator; and an output circuit which outputs digital data corresponding to an analog signal input to the input terminal. In a first state in which a total voltage of a first analog signal and an offset voltage of the comparator is held in the correction capacitor, a second analog signal input to the input terminal is supplied to a non-inverting input terminal of the comparator, and the second analog signal or the total voltage is changed using the reference signal, thereby outputting, from the output circuit, digital data.

A media diverter system for directing a media sheet traveling along an input media path into either a first media path or a second media path. One or more roller assemblies are provided including a media-guiding roller having one or more grooves formed around the exterior surface, and an air source for selectively providing an air flow into one or more of the grooves, the air flow being directed between the media sheet and the exterior surface of the media-guiding roller thereby producing a Bernoulli force to draw the media sheet toward the media-guiding roller. A controller selectively activates the air source in at least one of the roller assemblies while the corresponding media-guiding roller rotates around its roller axis to draw the media sheet toward the exterior surface of the media-guiding roller, thereby directing the media sheet into either the first media path or a second media path.

A power converter with positive and negative supply rail outputs for feeding a single ended class D amplifier, the converter comprising a transformer arrangement, a supply pump reduction arrangement connected between the secondary windings and the positive and negative supply rail outputs, and a boost drive mode switching arrangement. A controller is adapted to control the power converter in a negate drive mode and a boost drive mode, wherein the output voltage in the boost mode is increased by means of the transformer and the boost drive mode switching arrangement. The output voltages on the positive and negative rails can be generated at two different output voltage levels without changing the duty cycle or dead time of the control signals.

An apparatus is described that includes an audio power amplifier having an input and an output. An alternating-current to direct-current power converter is coupled to the audio power amplifier in a single package to supply power to the audio power amplifier.

A voltage converter can be switched among two or more modes to produce an output voltage tracking a reference voltage that can be of an intermediate level between discrete levels corresponding to the modes. One or more voltages generated from a power supply voltage, such as a battery voltage, can be compared with the reference voltage to determine whether to adjust the mode. The reference voltage can be independent of the power supply voltage.

The present invention is a serial to parallel data conversion method and device where new serial data are stored within a first n-bit register prior to presentation at an n-bit parallel output. Subsequently, additional data are stored within a second n-bit register while the data stored within the first register are presented at the parallel output. Data storage and data presentation are thereafter alternated, thereby eliminating the problem of setup time seen in prior art.

An analog-to-digital converter can use a variable sampling rate. By using a variable sampling rate analog-to-digital converter and an anti-aliasing filter lower sampling rates, and accordingly, generally lower power consumption may be achieved. For example, a lower sampling rate can be used when it is determined that no undesirable signals are present and a higher sampling period can be used when an undesirable signal is present. Determining the presence of an undesired signal can be based on signal-to-noise ratio, over-sampling, bit error rate, using a detector, etc. An undesirable signal can be any signal that is close in frequency to a signal of interest or a signal farther away in frequency that has a relatively high amplitude. Sampling rate can be varied in a binary fashion, stepwise, continuously, etc.

A DC-DC converter includes a first amplifier that amplifies a first difference between a first reference voltage and a feedback voltage corresponding to an output voltage, a second amplifier that amplifies a second difference between the first reference voltage and an integrated value of the feedback voltage, and a controller that controls a switching circuit to change the output voltage when the first difference reaches the second different.

A method of operating a switching power converter may include determining an average value of a measured parameter for substantially each switching cycle, and adjusting a control parameter during substantially each switching cycle in response to a corresponding one of the average values. In one embodiment, the control parameter comprises a switch duty cycle, and the measured parameter comprises an output current. Determining the average value of the measured parameter may include obtaining a first sample of the measured parameter during a switching cycle, and calculating the average value of the measured parameter during the switching cycle in response to the first sample.

Efficiency of a switch mode power supply (SMPS) is optimized by operating the SMPS in an asynchronous mode when current being supplied therefrom is less than a certain current value and operating the SMPS in a synchronous mode when the current being supplied therefrom is equal to or greater than the certain current value. When the SMPS is operating in the synchronous mode high-side and low-side power transistors alternately turn on and off. When the SMPS is operating in the asynchronous mode only the high-side power transistor turns on and off and the low-side power transistor remains off. When charging a battery with the SMPS discharge of the battery is eliminated when operating in the asynchronous mode at a low current output.

A power conversion system has a power converter configured to receive an input voltage signal, convert the input voltage to an output voltage signal, and provide the output voltage signal to a load and a closed loop compensator configured to receive the output voltage signal and a reference voltage signal, the closed loop compensator configured to transmit an error signal indicative of a difference between the output voltage signal and the reference voltage signal. The power conversion system further has a pulse with modulator configured to receive the error signal and modulate a control signal with the error signal to control the output voltage signal, the pulse width modulator configured to transmit the control signal to the power converter and logic configured to receive the error signal and control the closed loop compensator based upon the error signal. A controller observes the error signal characterstics such as peak-to-peak values, frequency and phase and adjust the closed loop controller variables and other power converter system variables in order to improve the dynamic performance and improve stability.

A DC/DC converter arrangement includes an input terminal to receive a supply voltage, an output terminal to provide an output voltage and a switching arrangement, including a coil and at least two switches to provide a Buck-Boost conversion. The arrangement further includes a current detection circuit which is coupled to the switching arrangement for sensing a coil current and a comparator, including a first input which is coupled to the output terminal and a second input which is coupled to an output of the current detection circuit. An output of the comparator is coupled to the switching arrangement. Furthermore, the arrangement includes a ramp generator which is coupled to the first or the second input of the comparator.

The present disclosure is directed to a voltage-to-current sensing circuit having a bias terminal configured to receive a reference voltage, an offset terminal configured to receive an offset current, and an operational amplifier configured to output a low voltage signal. The device includes a first amplifier having first and second high voltage inputs configured to receive a first voltage difference across a sense component on a high voltage line and to generate a first current, a second amplifier having first and second low voltage inputs configured to receive a second voltage difference between the bias terminal and the offset terminal and to generate a second current, a summing circuit configured to provide an intermediate voltage corresponding to a sum of the first and the second currents, and a low-voltage transistor coupled to an output of the amplifier and controlled by the intermediate voltage to generate the output current.

A controller used in a buck-boost converter includes a clock generator, an error amplifying circuit, a comparing circuit, a proportional sampling circuit, a logic circuit, a pulse width increasing circuit, first and second driving circuits. Based on a clock signal generated by the clock generator, the proportional sampling circuit samples the difference between a current sensing signal and a compensation signal generated by the error amplifying circuit, and generates a proportional sampling signal. The pulse width increasing circuit generates a sum control signal based on the proportional sampling signal and a logic control signal generated by the logic circuit, wherein a modulation value adjusted by the proportional sampling signal is added to the pulse width of the logic control signal to generate the pulse width of the sum control signal. The first and second driving circuits generate driving signals based on the sum control signal and the logic control signal.

A method for controlling voltage crossing a power switch of a switched-mode power converter includes the steps of: controlling a switch frequency of the power switch of the switched-mode power converter to a first frequency as activating the switched-mode power converter; and then changing the switch frequency of the power switch to a second frequency after the switched-mode power converter is activated for a predetermined time; wherein the first frequency is lower than the second frequency.

In one implementation, a modular power converter having a reduced switching loss includes a package, a field-effect transistor (FET) including a gate terminal, a drain terminal, and a source terminal, and fabricated on a semiconductor die situated inside the package, and a driver circuit inside the package. The driver circuit is configured to drive the gate terminal of the FET. The driver circuit is further configured to sample a drain-to-source voltage (VDS) of the FET directly from the drain terminal and the source terminal, thereby enabling the reduced switching loss.

A “windowless” H-bridge buck-boost switching converter includes a regulation circuit with an error amplifier which produces a ‘comp’ signal, a comparison circuit which compares ‘comp’ with a ‘ramp’ signal, and logic circuitry which receives the comparison circuit output and a mode control signal indicating whether the converter is to operate in buck mode or boost mode and operates the primary or secondary switching elements to produce the desired output voltage in buck or boost mode, respectively. A ‘ramp’ signal generation circuit operates to shift the ‘ramp’ signal up by a voltage Vslp(p−p)+Vhys when transitioning from buck to boost mode, and to shift ‘ramp’ back down by Vslp(p−p)+Vhys when transitioning from boost to buck mode, thereby enabling the converter to operate in buck mode or boost mode only, with no need for an intermediate buck-boost region.

This disclosure relates to radio frequency (RF) power converters and methods of operating the same. In one embodiment, an RF power converter includes an RF switching converter, a low-drop out (LDO) regulation circuit, and an RF filter. The RF filter is coupled to receive a pulsed output voltage from the RF switching converter and a supply voltage from the LDO regulation circuit. The RF filter is operable to alternate between a first RF filter topology and a second RF filter topology. In the first RF filter topology, the RF filter is configured to convert the pulsed output voltage from a switching circuit into the supply voltage. The RF filter in the second RF filter topology is configured to filter the supply voltage from the LDO regulation circuit to reduce a ripple variation in a supply voltage level of the supply voltage. As such, the RF filter provides greater versatility.

This disclosure relates to radio frequency (RF) power converters and methods of operating the same. In one embodiment, an RF power converter includes an RF switching converter, a low-drop out (LDO) regulation circuit, and an RF filter. The RF filter is coupled to receive a pulsed output voltage from the RF switching converter and a supply voltage from the LDO regulation circuit. The RF filter is operable to alternate between a first RF filter topology and a second RF filter topology. In the first RF filter topology, the RF filter is configured to convert the pulsed output voltage from a switching circuit into the supply voltage. The RF filter in the second RF filter topology is configured to filter the supply voltage from the LDO regulation circuit to reduce a ripple variation in a supply voltage level of the supply voltage. As such, the RF filter provides greater versatility.

A switching power converter includes a voltage source that provides an input voltage Vin to an unregulated DC/DC converter stage and at least one buck-boost converter stage to produce a desired output voltage Vout. The unregulated DC/DC converter stage is adapted to provide an isolated voltage to the at least one regulated buck-boost converter stage, wherein the unregulated DC/DC converter stage comprises a transformer having a primary winding and at least one secondary winding and at least one switching element coupled to the primary winding. The at least one buck-boost converter stage is arranged to operate in a buck mode, boost mode or buck-boost mode in response to a mode selection signal from a mode selection module. By influencing the pulse width modulation output power controller the at least one buck-boost converter stage is arranged to produce one or multiple output voltages.