A method and device for the cleaning of spiral wound membranes. In the device two or more spiral wound membranes are included in series in pressure tubes. The membranes are cleaned by longitudinal rinsing with water, in which a well-dissolvable gas has been dissolved. In the device for the purification of an aqueous fluid with spiral wound membranes, the membranes can be longitudinal rinsed with water, in which a well-dissolvable gas has been dissolved. As gas that is well-dissolvable preferably CO2 gas or a mixture of gasses is used.

A method and apparatus of sanitizing drinking water to be dispensed from a water dispenser having a reservoir includes the steps of providing the ozone gas generator that generates an ozone gas stream, transmitting the ozone gas stream from the generator to the water dispenser reservoir, mechanically breaking up the ozone gas stream inside the reservoir to produce ozone gas bubbles, and using the ozone gas bubbles to disinfect water in the reservoir. The ozone gas stream can be mechanically broken up using a pump such as, for example, an impeller type pump.

This is a scalable water cleansing system intended for very low technology primitive communities buildable for between $600 and $1,000 of parts. A gravity feed system is contemplated with one or more of an initial filtering stage(s), a settling stage, a UV treatment stage, and an ozonator stage. A stand-alone power system with solar power needing no infrastructure is contemplated to enhance purification. The system can improve the worst of water quality, including for small groups; and under some conditions to end up with clean water of a quality found in developed countries with mature water systems. For water to the site in communities with low precipitation, the water brought in would be emptied into the initial stage of the water cleansing system, and the person who brought the water would draw from the last stage most or all of the amount of water carried in.

An apparatus for providing magnetic fluid treatment is described. The apparatus includes a serial coupling of conduit segments forming a conduit. At least two of the conduit segments are constructed of a magnetically conductive material and at least one of the conduit segments is constructed of a non-magnetically conductive material and positioned in between the conduit segments constructed of the magnetically conductive material to establish a non-magnetically conductive region. At least one electrical conductor encircles at least a section of the outer surface of the serial coupling of conduit segments. Energizing the electrical conductor establishes a magnetic field having lines of flux directed along a flow path of the conduit and concentrated in the non-magnetically conductive region of the conduit.

A device for filtering liquids has a container, units for introducing a liquid to be filtered into the container, a container outlet for unfiltered liquid to be discharged from the container, and at least one rotor, which is drivable to rotate around the container axis. The rotor has a hollow shaft mounted in an end wall and a support device fastened thereon for filter elements, which are arranged with a clearance to the container axis or rotate around their own axis. The interior of the filter elements opens via the support device and the hollow shaft out of the container as the discharge for filtered liquid. To provide improved filtration conditions, the container internal radius of the inner wall of the container circumferential shell is enlarged up to a maximum in the container circumferential direction while bulging the inner wall between two minima. The bulge forms a guide unit which guides the liquid toward the filter elements.

Disclosed herein are an apparatus and method of increasing dialysis dose and waste removal with the introduction of mechanical energy, such as vibration, to a hemodiafiltration membrane The method generally includes providing a dialyzer that includes a vibration element in engaged vibratory communication with a hemodiafiltration membrane The method also includes enabling extracorporeal flow of pre-dialyzed blood and a dialysate through the dialyzer and respectively past opposing surfaces of a vibrating hemodiafiltration membrane to achieve a solute clearance from the pre-dialyzed blood that is at least about 10% greater than a solute clearance from the pre-dialyzed blood obtained in the absence of the engaged vibratory communication Various apparatus are also disclosed, each of which includes a vibration element in vibratory communication with the dialyzer.

Provided is a filter device for filtering liquid by passing it through one or more filtering media. The filter device comprises a cartridge defining a treatment region filled with said one or more filtering media and has a liquid inlet and a liquid outlet. A locking mechanism may be located within a liquid flow through the cartridge and configured to lock at least one of the liquid inlet and the liquid outlet upon expiration of life time of said at least one filtering medium.

An apparatus for treating a flow of fluid with microwave radiation, the apparatus comprising: a vessel having a sidewall and opposed first and second end walls defining a substantially cylindrical chamber, the first end wall being disposed a predetermined distance d1 from the second end wall; a pipeline for flowing fluid through, the pipeline passing through the first end wall towards the second end wall of the vessel, the chamber and the pipeline being substantially co-axial and the pipeline being substantially transparent to microwave radiation; and a microwave radiation inlet in the side wall of the vessel for admitting microwave radiation of wavelength λ into the chamber, wherein the distance d1 is substantially equal to an integral multiple of λ/2 so that the chamber is a microwave resonator.

A microfluidic device with a filter includes a substrate; a flowpath including a well formed in the substrate in fluid communication with a channel formed in the substrate; and a filter disposed across the flowpath and associated with the channel.

The present invention is a method and material for using a sorbent material to capture and stabilize mercury. The method for using sorbent material to capture and stabilize mercury contains the following steps. First, the sorbent material is provided. The sorbent material, in one embodiment, is nano-particles. In a preferred embodiment, the nano-particles are unstabilized nano-Se. Next, the sorbent material is exposed to mercury in an environment. As a result, the sorbent material captures and stabilizes mercury from the environment. In the preferred embodiment, the environment is an indoor space in which a fluorescent has broken.

A filter device is disclosed. The device includes at least one substantially flat filter media that may be encapsulated between non-permeable films. Some embodiments comprise ports for introducing a fluid to be filtered and for evacuating the filtered fluid. Various substrates may be employed therein in cooperation with the at least one filter media to enhance device performance. Also disclosed are various apparatuses configured to contain at least one filter device.

A supporting plate of a device is suggested. The device has at least one component and a housing for at least partly protecting the component. The supporting plate has at least one receiving element adapted for accepting the at least one component of the device in at least one of the following manners: in a form-closed manner, in a force-closed manner. The supporting plate is part of the housing.

The present invention relates to a means of dialysis for removing protein-bound substances from a biological fluid, especially blood or blood plasma, which contains at least one means for solubilizing protein-binding substances to be removed into the biological fluid and/or dialysis fluid, and to a process for removing protein-bound substances from a biological fluid.

One embodiment of the present invention relates to a method for inflating a chamber within an inflatable avalanche safety system. The method includes providing an inflatable avalanche safety system including an inflatable chamber; receiving a user-triggered action intended to activate the avalanche safety system; transmitting ambient air from an external region to within the inflatable chamber; and inflating the inflatable chamber entirely with the transmitted external ambient air to a particular internal pressure and shape configured to protect the user from burial during an avalanche. The transmission of ambient air within the inflatable chamber may be accomplished with a fan or an electrical component.

A system for filling a jar with powdery material, for example for the manufacture of nuclear fuel, including a device for connection between the jar and a material feed system, where the device includes: a stationary connection portion connected to the feed system,a connection portion which moves relative to the stationary connection portion intended to be connected to the container's filling orifice, where the moving connection portion includes in the area of a downstream end a lip seal to achieve a tight connection by contact with the contours of the jar's filling orifice and where the said downstream end is connected to the stationary connection portion by a bellows so as to provide mechanical disengagement between the downstream end of the moving connection portion and the stationary connection portion.

Method for filling containers with liquids, wherein the containers are filled using a plurality of controllable filling elements and the liquid is fed to these filling elements starting from a reservoir, common to the filling elements, for storing the liquid, wherein during the filling the containers are transported at least in sections along a circular track and wherein the filling of the containers by at least one filling element is controlled as a function of at least one first parameter characteristic of the liquid in the reservoir and this parameter is determined repeatedly at given intervals of time during the filling operation.

A container (1, 2) for storing and dispensing a liquid, the container including an access port (16) having a frangible seal (18) for allowing contained liquid to be dispensed. A vent (19) permeable to vapour but impermeable to liquid is also provided so that vapour may be vented from the interior of the container.

A refrigerator includes a refrigerator cabinet and a refrigerating compartment within the refrigerator cabinet. A beverage dispensing system is operatively connected to the refrigerator cabinet, the beverage dispensing system configured to dispense a stream of a beverage. The beverage dispensing system includes a light source and a light sensor positioned on opposite sides of the stream of the beverage. The beverage dispensing system is configured for detecting if dispensement of the beverage is occurring and characterizing the volume or amount of the beverage being dispensed.

Devices and methods for clamping a beverage extraction device to a beverage container, such as a wine bottle. One or more clamp arms may be arranged to clamp the extraction device to a wine bottle as well as allow the device to be supported upright on a table top. Clamp arms may include tab and ridge features that operate to properly engage and position a wide variety of different bottle neck shapes relative to the device. The one or more clamp arms may move the bottle neck distally, e.g., toward a resilient pad, so that the neck is suitably positioned relative to the device. Proper positioning and engagement of the neck may allow for desired piercing of a cork or other closure of the bottle by the device.

A gas filling system (1) includes a gas tank (30); a gas filling device (2) that fills gas into the gas tank (30); and a controller (24) that calculates a temperature increase ΔT and a pressure increase ΔP in the gas tank (30) during a predetermined period of time (t seconds) that elapses from a start of gas filling. The controller (24) selects a filling rate map (Ma, Mb) from a prepared filling rate map group on the basis of the calculated temperature increase ΔT and the calculated pressure increase ΔP. The gas filling device (2) carries out gas filling using the filling rate map selected by the controller (24).

A device, system and/or method for dispensing a fuel additive to a fuel tank that employs a fuel additive delivery device secured to an opening of the fuel tank. The delivery device is fluidly coupled to a fuel additive reservoir. The delivery device includes a cap that automatically opens or closes fluid communication with the fuel additive reservoir. The delivery device also includes a bore defined through the delivery device configured to receive a fuel filler spout with a fuel passageway outlet positioned in the bore such that, as fuel passes through the bore and into the fuel tank, the bore is configured to create a suction at the fuel additive outlet to pull fuel additive from the reservoir, through the delivery device, and into the fuel tank with the fuel.

A container and method are provided for storing fat containing liquid products. The container includes a body defining a storage chamber for receiving the product, and a container closure. A first material portion forms at least most of the surface area overlying the storage chamber that can contact any product therein. Neither the body nor the first material portion leach more than a predetermined amount of leachables into the product or undesirably alter a taste profile thereof. A needle penetrable and thermally resealable second material portion either (i) overlies the first material portion and cannot contact any product within the storage chamber, or (ii) forms a substantially lesser surface area overlying the storage chamber that can contact any product therein in comparison to the first material portion. A sealing portion is engageable with the body to form a substantially dry hermetic seal between the container closure and body.

A communication device or auxiliary ECU is activated when a fuel door of a fuel cell vehicle is open. Upon closing the fuel door, the communication device/ECU is shut off. The communication device/auxiliary ECU is operational regardless of whether the keys in the vehicle or not. This assures that communication of information can occur when a refueling station is most likely to request the information, i.e. when the fuel door is open. A temperature measurement device may monitor a vehicle tank temperature, communicate the tank temperature data to a filling station, and confirm that the tank temperature data is associated with the tank being filled.

A cover for covering a spout of a fuel dispenser when the fuel dispenser is not in use includes a sheath having an elongated cavity which is shaped and dimensioned to longitudinally receive the spout of the fuel dispenser. The sheath is fabricated from a fuel absorbent material. After the fuel dispenser is used, the sheath is installed over the spout of the fuel container, absorbs any residual fuel, and prevents contaminants from collecting on the spout. In an embodiment, the sheath has a hole which receives the hanger of a fuel nozzle and holds the sheath in place on the spout.

An apparatus to introduce a defined amount of a second powder into a process container in which a first powder or a powder mixture is present, includes a coupling flange having a cover flap located on the process container. The second powder is introduced into a tubular cartridge mounted displaceably in a transport unit, the latter including a joining flange having a cover flap. The joining flange is joinable to the coupling flange so that the respective cover flaps can be opened, and the cartridge can be pushed through openings thereby provided into the plane of the inner wall of the process container. The second powder is emptied from the cartridge into the process container by a delivery piston. The cartridge may include a piston rod having multiple pistons. Other embodiments include a double piston, a rotatable cartridge core or a rotary closure.

Provided is a gathering device for gathering plastic members. The gathering device includes a gathering portion and a tray detachably connected to the gathering portion. The gathering portion includes an outer shell, a hollow inner shell and a number of fans. The inner shell is received in the outer shell. The inner shell includes a number of vent. The fans are positioned between the outer shell and the inner shell for blowing ions into the inner shell through the vents. The tray is configured for containing the plastic members passing through the gathering portion.

A conveying device for free-flowing fine-particle solids, in particular for powdery and/or granular (mixed) material, especially plastic granulate, includes a vertically arranged and flexibly mountable telescopic pipe for the conveyance of, preferably, polymer granulates, for example in a plant for the filling of polymer granulates.

A powder refilling device includes a refill powder chamber to accommodate a powder bag containing powder, an opener to open the powder bag inside the refill powder chamber, and a squeezer to squeeze the opened powder bag to discharge powder therefrom and reduce a volume of the opened powder bag.

The phase margin compensation method according to an exemplary embodiment of the present invention includes: outputting reference voltage (Vout2); outputting a first reference voltage (Vout1) actually supplied to the target circuit; comparing the reference voltage (Vout2) with the first reference voltage (Vout1) by the comparator; counting any section of an output signal (pulse signal) from the comparator by a predetermined frequency by the duty cycle calculator; and controlling a phase margin of a frequency of output voltage supplied to the target circuit by controlling buffer current based on the duty cycle ratios and the output bit information fed back from the duty cycle calculator.

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.

A power supply for a load control device generates a DC voltage and provides an asymmetrical output current, while drawing a substantially symmetrical input current. The power supply comprises a controllably conductive switching circuit for controllably charging an energy storage capacitor across which the DC voltage is produced. The energy storage capacitor begins charging at the beginning of a half-cycle and stops charging after a charging time in response to the magnitude of the DC voltage and the amount of time that the energy storage capacitor has been charging during the present half-cycle. The charging time is maintained substantially constant from one half-cycle to the next. The power supply is particularly beneficial for preventing asymmetrical current from flowing in a multiple location load control system having a master load control device supplying power to a plurality of remote load control devices all located on either the line-side or the load-side of the system.

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 some aspects of the invention, overcurrent protection is carried out by suppressing fluctuations in current flowing through a switching element after overcurrent detection. A peak current reaching time detection circuit detects a peak current reaching time needed until current flowing through a switching element reaches a peak value. A difference voltage detection circuit, including a ½ time detection circuit which detects a time of ½ an ON time of the preceding cycle of the switching element, detects difference voltage between reference voltage used when detecting overcurrent flowing to a load and a signal which has detected current flowing through the switching element for the ½ time. A delay time adjustment circuit, based on at least one of the peak current reaching time and difference voltage, carries out adjustment and control of a delay time occurring until the time when the switching element is turned off after detecting the overcurrent.

Methods and systems are described for providing power factor correction for high-power loads using two interleaved power factor correction stages. Each power factor correction stage includes a controllable switch that is operated to control the phasing of each power factor correction stage. The phasing of output current from the second power factor correction stage is shifted 180 degree relative to the output current from the first power factor correction stage.

In accordance with one embodiment of the present disclosure, a multi-phase voltage regulator may comprise a plurality of phases, each phase configured to supply electrical current to one or more information handling resources electrically coupled to the voltage regulator. A controller may be electrically coupled to the plurality of phases. The controller may designate at least one of the plurality of phases as a first state phase, and designate each of the plurality of phases not designated as a first state phase as a second state phase. The controller may alternate the designation of at least two of the plurality of phases between a first state phase and a second state phase. Each first state phase may be configured to supply a first electrical current regardless of electrical current demand. Each second state phase may be configured to supply a second electrical current based on the current demand.

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.

The invention relates to a system for eliminating current surges that includes a first voltage regulator (7) having a current limit programmable to a value (I(limit)) that depends on the value of the intermittent current surges (IO(surge)) required by the intermittent load (3) and the relationship thereof to the work cycle, a second voltage regulator (9), a condenser (4) connected between the first and second regulators (7, 9), that loads when the current is no longer required and that unloads when there is a need for output current to provide current to the second regulator (9) which absorbs the changes in voltage produced by the loading/unloading of the condenser and provides a constant voltage for any value of the required output current surge, independently of voltage changes in the condenser (4), and a control loop between a sensor for the output current provided to the load and an input limit (15) for the input current (II) in the first regulator (7). Thus, the input current (I(limit)) (1) and the output voltage (VLoad) are constant for any value of the output current surge (IO(surge)).

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 voltage regulator includes an amplifier having a first input coupled to a first reference voltage and a second input coupled to a voltage feedback signal; a multiplexer having a first input coupled to an output of the amplifier, a second input coupled to a voltage clamp signal, and a control input; and a control circuit having a first input coupled to an over current indicator, a second input coupled to a no over voltage indicator, a third input coupled to a timer signal, and an output coupled to the control input of the multiplexer.

A power supply device includes a first converter which converts an input voltage to a first voltage, a second converter which converts the first voltage from the first converter to a second voltage, a voltage comparison section which compares the first voltage outputted from the first converter with a predetermined reference voltage, a voltage comparison result output section which outputs a first signal until the first voltage is determined to be higher than the predetermined reference voltage by the voltage comparison section and retains a second signal as an output after the first voltage is determined to be higher than the predetermined reference voltage, and a converter control section which controls the second converter to stop when the first signal is outputted from the voltage comparison result output section and controls the second converter to operate when the second signal is outputted from the voltage comparison result output section.

A charge pump regulator circuit includes a voltage controlled oscillator and a plurality of charge pumps. The voltage controlled oscillator has a plurality of inverter stages connected in series in a ring. A plurality of oscillating signals is generated from outputs of the inverter stages. Each oscillating signal has a frequency or amplitude or both that are variable dependent on a variable drive voltage. Each oscillating signal is phase shifted from a preceding oscillating signal. Each charge pump is connected to a corresponding one of the inverter stages to receive the oscillating signal produced by that inverter stage. Each charge pump outputs a voltage and current. The output of each charge pump is phase shifted from the outputs of other charge pumps. A combination of the currents thus produced is provided at about a voltage level to the load.

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.