Abstract: The present invention discloses circuits and methods for high efficiency and fast response AC-DC voltage converters. In one embodiment, an AC-DC voltage converter can include: (i) a first stage voltage converter having an isolated topology with a power factor correction function, where the first stage voltage converter is configured to convert an AC input voltage to a series-connected N branches of first stage voltages, where N is a positive integer of at least two; (ii) a second stage voltage converter having a non-isolated topology, where the second stage voltage converter is configured to convert one of the N branches of the first stage voltages to a second stage voltage; and (iii) where the second stage voltage and a remaining of the N branches of the first stage voltages are configured to be series-connected and converted to a DC output voltage.

Abstract: A power converter for an engine generator includes an insulative support that receives and supports circuit components for converting incoming AC power to desired power, such as power suitable for a welding application. One or more rectifier modules are provided that are received and supported by the support. Three such modules may be provided for receiving three phase power from a generator. DC power from the rectifier module is applied to DC bus plates. The plates may be coupled to capacitors. A power conversion circuit, such as a buck converter, is coupled to the DC bus plates to convert the DC power to output power.

Abstract: A rectifier module comprises a conductive housing made of injection molded aluminum or aluminum alloy. Diodes are inserted into recesses formed in the housing. The housing is placed at an alternating input potential during operation, and transmits alternating current input power to the diode modules for conversion to direct current power. Multiple recesses may be provided for high and low side diodes, of which there may be one or many. Multiple such modules may be provided for converting multiple phases of input power to direct current power.

Abstract: An energy recovery system is provided that can be used in place of a resistive termination. The energy recovery system can simulate the behavior and performance of a resistive termination, while recovering at least some of the energy that would otherwise have been dissipated within the termination. In one embodiment, the energy recovery system includes a rectification system having a plurality of tuned rectifier circuits and an RF input network to provide input power distribution to the plurality of tuned rectifier circuits and input impedance shaping to shape the collective input impedance of the plurality of tuned rectifier circuits as seen at the RF input port of the RF input network.

Abstract: A resistance compression network uses transmission line sections having asymmetric lengths to compress the resistance range of multiple loads. In some embodiments, the characteristic impedance of the transmission line sections is related to the geometric mean of the load resistance range. The resistance compression network may be used within, for example, an energy recovery system or in any other application where a reduction in the resistance range of multiple loads is desired.

Abstract: Methods and apparatus provide for: a rectification circuit operating to convert a source of AC power into a final DC power source; a rectification filtering capacitance operating to at least partially smooth a voltage of the final DC power source, which exhibits a voltage sag and recovery characteristic in response to time-variant current drawn therefrom; a power amplification circuit drawing power from the final DC power source and producing an output signal, for driving a speaker, having audible characteristics influenced by the voltage sag and recovery characteristic of the final DC power source; and a control circuit operating to continuously vary, in response to user input, one or more parameters of the voltage sag and/or recovery characteristic of the final DC power source.

Abstract: A flyback converter includes input terminals and output terminals. A transformer with a first winding and a second winding are inductively coupled. A first switching element is connected in series with the first winding and a first series circuit with the first switching element, the first winding being coupled between the input terminals. A rectifier arrangement is connected in series with the second winding and a second series circuit with the rectifier arrangement, the second winding being coupled between the output terminals. The rectifier arrangement includes a second switching element. A control circuit is configured in one drive cycle to switch on the first switching element for a first time period. After the first time period the second switching element is switched on for a second time period. A third time period is determined between an end of the second time period and the time at which the transformer assumes a predetermined transformer state.

Abstract: A three phase rectifier rectifies received three phase a.c. power to generate a ripple d.e. voltage. A power distribution bus conveys distribution power comprising the ripple d.c. voltage or an a.c. voltage derived therefrom to a location of an LED based lamp that is distal from the three phase rectifier. Additional circuitry disposed with the LED based lamp drives the LED based lamp using the distribution power.

Abstract: A light emitting diode current-balancing driving circuit is provided. In accordance with the first aspect of the present invention, a light emitting diode current-balancing driving circuit is provided. The light emitting diode current-balancing driving circuit includes a plurality of rectifiers; a current-balancing circuit having a plurality of capacitors respectively coupled to the plurality of rectifiers; and a plurality of diodes electrically connected to the plurality of rectifiers respectively.

Abstract: A power supply includes two or more input waveforms being shaped or selected so that after being separately level-shifted and rectified, their additive combination results in a DC output waveform with substantially no ripple. The power supply may comprise a waveform generator, a level conversion stage for step up or down conversion, a rectification stage, and a combiner. The waveform generator may generate complementary waveforms, preferably identical but phase offset from each other, such that after the complementary waveforms are level-converted, rectified and additively combined their sum will be constant, thus requiring no or minimal smoothing for generation of a DC output waveform. The level conversion may be carried out using transformers or switched capacitor circuits. Feedback from the DC output waveform may be used to adjust the characteristics of the input waveforms.

Abstract: A power converting apparatus is configured with single-phase sub-converters (4) connected to AC input lines of individual phases of a three-phase main converter (3) in series therewith. In a control device (12) for performing output control of the power converting apparatus, a current command value calculating circuit (20) which adjusts a DC voltage command given to the main converter (3) so that DC voltages of the sub-converters (4) follow a command and generates AC current commands so that a DC voltage of the main converter (3) follows the DC voltage command is configured with a CPU, and AC currents are controlled by switching output voltage levels of the sub-converters (4) at an AC side thereof so that deviations of instantaneous AC current values from the AC current commands become smaller.

Abstract: A switching element of a power converter generates a low voltage, using a current flowing in the power converter, and supplies a power to drive itself. A switching element of a power converter for conversion from direct current into alternate current or from alternate current into direct current includes: a terminal and a terminal which are used in building the switching element itself in the power converter; a capacitor, a high-side controllable switch and a low-side controllable switch enabling outputting the voltage of the capacitor, the voltage being output between the terminal and the terminal, and a self-supply power source for supplying a power to drive the bi-directional chopper switching element itself, using a current flowing in the capacitor.

Abstract: A power supply apparatus of a home appliance which meets standby power regulation of 0.5 watts using one SMPS. As compared with a general circuit which meets the standby power regulation using two or more SMPSs, it may be possible to curtail expenses required for addition of a separate standby only SMPS and miniaturize a PCB, resulting in a reduction in cost. Further, in a washing machine employing a motor, a circuit is provided to bypass a back EMF generated in the motor even if AC power is not supplied to the washing machine due to occurrence of a power failure or unplugging of the washing machine. Therefore, it may be possible to prevent a PCBA from being damaged due to the back EMF.

Abstract: An energy harvesting device (EHD) and method including a hollow outer envelope (201) having an inner wall (200) with a first predetermined magnetic field distributed on an inner surface of the inner wall, at least one inner core (202), free to move in the hollow envelope (200) characterized by a second predetermined magnetic field distributed on an inner surface of the at least inner core, the inner core being characterized by one or more convex projections of magnetically active material, at least one conducting loop (203) disposed at locations selected from the group consisting of the outer envelope and the at least inner core, so as to be suffused with magnetic flux due to the magnetic field distributions of the at least one inner core and the at least one outer envelope and generating an alternating current due to movement of the inner core within the outer envelope and a rectifying circuit in electrical connection with the at least one conducting loop (203) rectifying the alternating current into a curre

Abstract: An inverter circuit is connected in series to an AC power supply, and at the subsequent stage, a smoothing capacitor is connected via a converter circuit including semiconductor switching devices. A control circuit controls the converter circuit by providing a short-circuit period for bypassing the smoothing capacitor in each cycle, and controls the inverter circuit to improve the power factor of the AC power supply by using a current instruction such that the voltage of the smoothing capacitor becomes a target voltage. When the voltage of a DC voltage source of the inverter circuit has exceeded a predetermined upper limit, the control circuit increases the current instruction to control the inverter circuit, thereby increasing the discharge amount of the DC voltage source. Thus, even if the voltage variation of the DC voltage source of the inverter circuit increases, it is possible to stably continue the control.

Abstract: A three-phase power supply with a three-phase three-level DC/DC converter includes a full-bridge thyristor converter with three-set four in-series power switch elements, a three-phase isolated transformer, a full-bridge rectifier, a rectifying circuit, and a low-pass filtering circuit. The three-phase power supply is used to deliver power energy from the AC input voltage to the load. The power switch elements, which separated to each other at 120-degree phase differences, are controlled through a phase shift scheme. Therefore, the three-level circuit structure is provided to reduce withstanding voltage of the power switch elements, further the zero-voltage switching (ZVS) is achieved by the isolated transformer and the power switch elements to increase the efficiency of the DC/DC converter.

Abstract: Provided is a method for detecting a PoE (power over Ethernet) device comprising applying a positive polarity of a first current source to one of a first and second data pairs of an Ethernet connection to a powered device (PD) and a negative polarity of the first current source to the other of the first and second data pairs, applying a positive polarity of a second current source to a first spare pair of the Ethernet connection and a negative polarity of the first current source to a second spare pair of the Ethernet connection, simultaneously measuring a first voltage across the first current source and a second voltage across the second current source, discontinuing application of the first current source and measuring a third voltage across the second current source, and determining a configuration of the PD using the measured first, second and third voltages.

Abstract: A method for providing a switching order signal to a cell of a cascaded two-level converter is provided. The cell includes a capacitor parallel-connected with two series-connected semiconductor devices. The cascaded two-level converter includes two or more of the cells cascade connected and arranged in a phase, divided into two phase arms, between a first pole and a second pole of a direct voltage side. The method includes measuring voltages of the capacitor of the cell; calculating a compensated voltage reference based on a voltage reference and the measured voltages of the capacitors, wherein the voltage reference corresponds to a desired ac current to be output on an ac-side; using the compensated voltage reference to calculate a switching order signal, and providing the switching order signal to the cells.

Abstract: A redundant AC-DC power supply system and method is disclosed. A first AC-DC power converter is configured to generate a first output voltage and a first relay is configured to selectively couple and decouple the first AC-DC power converter to an output of an output circuit. A second AC-DC power converter is configured to generate a second output voltage. A second relay is configured to selectively couple and decouple the second AC-DC power converter to the output. A controller is configured to operate the first and second AC-DC power converters and the first and second relays to provide redundant sources of power for the output and to mitigate circulating current flow between the first and second AC-DC power converters.

Abstract: Controlled by switching is which reactor in a reactor group present between a power source and a three-level converter is to be connected to an intermediate point that outputs a midpoint potential. In the switching, the closer to the command value of the midpoint potential the command values of input potentials of the converter are, the greater the duty at which corresponding reactors are connected to the intermediate point is for pulse width modulation. Additionally, a predetermined range to be compared with the command values has a predetermined potential width with respect to an AC waveform centered around the command value of the midpoint potential.

Abstract: We describe a photovoltaic power conditioning unit comprising: both dc and ac power inputs; a dc link; at least one dc-to-dc converter coupled between dc input and dc link; and a dc-to-ac converter coupled between dc link and ac output. The dc-to-dc converter comprises: a transformer having input and output windings; an input dc-to-ac converter coupled between dc input and input winding; and an ac-to-dc converter coupled between output winding the dc link. The output winding has a winding tap between the first and second portions. The ac-to-dc converter comprises: first and second rectifiers, each connected to a respective first and second portion of the output winding, to the dc link and winding tap; and a series inductor connected to the winding tap. Rectifiers are connected to the winding tap of the output winding via the series inductor wherein the series inductor is shared between the first and second rectifiers.

Abstract: Even if a network setting changes due to power interruption or the like, communication for controlling the operating status of load devices of an uninterruptible power supply is enabled to continue. A network communication system (1) for the uninterruptible power supply comprises UPS member controllers (12 and 13) and a UPS group controller (11) which are connected in a network (2) to control the operating status of the load devices (3) of the uninterruptible power supply (1). The UPS group controller (11) and the UPS member controllers (12 and 13) execute data communication according to a predetermined communication protocol (Internet Protocol or the like) through the network (2), and these controllers transmit/receive data in which specific identification information issued for each of the UPS member controllers (12 and 13) is added to control data as communication data in the data communication according to the predetermined communication protocol.

Abstract: Aircraft power systems, aircraft galley systems, and methods and systems for managing power distribution to aircraft galley systems are disclosed herein. In one embodiment, an aircraft system can include an aircraft power source and at least first and second galley appliances operably coupled to the aircraft power source. The aircraft system can further include a controller operably coupled to the first and second galley appliances. The controller can be configured to receive a first power request from the first galley appliance and a second power request from the second galley appliance. The controller can be further configured to sort the first and second power requests and distribute power to the first and second galley appliances from the aircraft power source based on the sorting of the first and second power requests.

Abstract: A 24-pulse composite AC-to-DC converter is a converter using two or more conversion methods in parallel. The converter may include a main rectifier receiving at least a portion of an input AC signal, an autotransformer having an output voltage with lower amplitude than the input AC signal, and a plurality of auxiliary bridge rectifiers, each receiving the output from each leg of the autotransformer. In one embodiment of the invention, the main rectifier may receive a substantial portion of the load current, allowing each of the auxiliary bridge rectifiers to be generally smaller than the main rectifier.

Abstract: Systems, methods and devices for power generation systems are described. In particular, embodiments of the invention relate to the architecture of power conditioning systems for use with fuel cells and methods used therein. More particularly, embodiments of the present invention relate to methods and systems usable to reduce ripple currents in fuel cells.

Abstract: A regulated power supply apparatus and method are provided. The apparatus includes a converter circuit for generating a regulated voltage signal. The converter circuit includes a first switching circuit and a second switching circuit both coupled with an output circuit. A first and a second transformer include a first and a second secondary, which are coupled with each other in series or alternatively, coupled with each other in parallel. An input rectifier circuit is coupled with the first and the second switching circuit. The input rectifier circuit is configured for receiving an AC input voltage and for generating a rectified voltage. The input rectifier circuit includes controlled switches and a first and second configuration of a bridge rectifier that couples the first and second switching circuits in series or parallel depending if the AC input power signal is “high-line” or “low-line.” A controller circuit is provided for enabling either the first configuration or the second configuration.

Abstract: A voltage adjusting circuit includes an inducing circuit configured to induce a voltage from electromagnetic waves, a first rectifying circuit configured to rectify an output signal of the inducing circuit, a second rectifying circuit configured to rectify the output signal of the inducing circuit, a first regulator configured to regulate an output signal of the first rectifying circuit, and a second regulator configured to regulate an output signal of the second rectifying circuit.

Abstract: A system for increasing parallel rectifier DC power system efficiency. In one embodiment, the system includes: (1) a controller configured to sense and classify a load magnitude change into groups including large load transients and moderate load transients and (2) at least one rectifier coupled to the controller and configured to transition from a stand-by mode to an active mode upon an occurrence of one of a large load transient and a moderate load transient.

Abstract: A PFC rectifier comprises a first converter having a first output capacitor and a second converter having a second output capacitor. The first and second capacitors are coupled to each other to increase the output voltage of the PFC rectifier. For example the first or second output capacitors can be serially coupled to each other. At least one or both of the first or second converters comprise buck or buck-boost converters, including inverting or non-inverter buck converters. The first and second converters can also form a bi-directional ac-ac inverter.

Abstract: A converter controllable in regenerative running mode, which is a power converting apparatus capable of suppressing harmonics without increasing the size of a reactor, and reducing power loss and electromagnetic noise. A power converter is configured by directly connecting AC sides of single-phase sub-converters having a DC voltage lower than a DC voltage of a 3-phase main converter to AC input lines of individual phases thereof in series. The main converter is driven by one gate pulse per half recurring cycle and a voltage produced by each sub-converter at AC terminals thereof is controlled to match a difference between an AC power supply voltage and a voltage produced by the main converter at AC terminals thereof, whereby phase voltages of the power converter are generated as the sums of phase voltages of the individual converters.

Abstract: An 18n-pulse rectifier for AC drive systems having a separate DC bus for each output phase is described, where n=any positive integer. The rectifier uses three separate phase rectifiers, one for each output phase of a transformer, each comprised of n six-pulse diode bridges connected in series or parallel. Each phase rectifier may be supplied with n unique sets of phase inputs from a transformer secondary winding. In some configurations, the n sets of inputs provided to each rectifier are separated by 60/n degrees of phase (when n is greater than 1), while the corresponding inputs to neighboring rectifiers are separated by 20/n degrees of phase. In a 36-pulse example, the phase offsets for the inputs provided to the rectifiers may be ?25° and +5° from the transformer primary winding (for the first rectifier), ?15° and +15° from the primary winding (for the second rectifier) and ?5° and +25° from the primary winding (for the third rectifier).

Abstract: A transformer accepts an AC voltage from an AC power source, transforms the AC voltage, and supplies the transformed AC voltage to first rectifying circuits. Similarly, another transformer accepts an AC voltage from an AC power source, transforms the AC voltage, and supplies the transformed AC voltage to second rectifying circuits. The first rectifying circuits convert the accepted AC voltage into a positive DC voltage, and the second rectifying circuits convert the accepted AC voltage to a negative DC voltage. The positive DC voltage and the negative DC voltage then are superimposed and outputted to a secondary side of a transformer in the AC circuits. The AC voltage outputted from the transformers in the AC circuits and the DC voltage formed by superimposing the positive and negative DC voltages outputted from the first and second rectifying circuits are further superimposed, and supplied to each developing section.

Abstract: The present invention relates to a circuit minimizing standby power in a power adapter with a power-frequency transformer (T1), which includes a sensing circuitry (1), a driving circuitry (2), a switching circuitry (3) and a resistive element (Z). When the sensing circuitry (1) senses a power supply signal of the power-frequency transformer (T1) in work mode, the switching circuitry (3) shorts the resistive element (Z); and when the power-frequency transformer (T1) is in standby mode, the electronic switch (3) is switched off and the resistive element (Z) is coupled to the power-frequency transformer (T1). The circuit attached to the power adapter reduces the standby power consumption very much, and achieves energy-saving effect with low cost.

Abstract: Optimal operating techniques are disclosed for using coreless printed-circuit-board (PCB) transformers under (1) minimum input power conditions and (2) maximum energy efficiency conditions. The coreless PCB transformers should be operated at or near the ‘maximum impedance frequency’ (MIF) in order to reduce input power requirement. For maximum energy efficiency, the transformers should be at or near the “maximum efficiency frequency” (MEF) which is below the MIF. The operating principle has been confirmed by measurement and simulation. The proposed operating techniques can be applied to coreless PCB transformers in many circuits that have to meet stringent height requirements, for example to isolate the gates of power MOSFET and IGBT devices from the input power supply.

Abstract: This switching power supply provides a stable output. In the switching power supply, at least pairs of secondary side coils are connected to each of the center tap rectifier circuits and the secondary side coils of each of the center tap rectifier circuits are disposed in the core portions (cores) of mutually different transformers.

Abstract: Methods and systems with a step-up converter are provided based on a boost converter. In one aspect, a step-up converter includes: a boost converter having a first inductor; a second inductor paired on a core with the first inductor; and a rectifier circuit coupled with the second inductor to generate a direct current output.

Abstract: An apparatus for generating a compensation signal for a power converter where the second harmonic ripple on the voltage bus is substantially removed from the compensation signal. The apparatus comprises a frequency-locked clock generator, a bus voltage data generator, a stack, and a compensation signal generator. The frequency-locked clock is coupled to the power converter voltage bus that contains harmonics of the AC line frequency. The clock generator frequency locks to the second harmonic of the AC line frequency and creates a system clock which is used for the synchronous operations throughout the apparatus. The bus-voltage data generator inputs a power converter scaled-bus voltage, generates bus-voltage data at a sampling rate which is determined by the coupled system clock. The output of the bus-voltage generator is input into a stack.

Abstract: The first choke coil and the third choke coil are not magnetically coupled to the second choke coil and the fourth choke coil. Therefore, even in a case where a structure for increasing the heat radiation area is adopted, a pair of the first and third choke coils and a pair of the second and fourth choke coils located between the two ends of the capacitor maintain a state of equilibrium so as to be inversely proportional to mutual loss without affecting one another, and the output therefore stabilizes. Accordingly, the output of the switching power supply, that is, the rectified and smoothed output across the two ends of the capacitor stabilizes.

Abstract: A power conversion device includes input terminals, first output terminals, second output terminals, and an insulation transformer. The insulation transformer includes a primary coil and a secondary coil of equal inductance. The polarity of one end of the primary coil is same as the polarity of the other end of the secondary coil. One of the first output terminals is connected to an input terminal and the one end of the primary coil. The other of the first output terminals is connected to an input terminal and one end of the secondary coil. One of the second output terminals is connected to the other end of the primary coil and the other end of the secondary coil. The other of the second output terminals is connected to an input terminal.

Abstract: A power supplying apparatus includes a conversion device to convert direct current (DC) power from a battery set into alternating current (AC) power. A current transformer arrangement may generate a DC charging signal based on the AC power and provide the DC charging signal to the battery set. The current transformer may include a plurality of current transformers.

Abstract: Aircraft power systems, aircraft galley systems, and methods and systems for managing power distribution to aircraft galley systems are disclosed herein. In one embodiment, an aircraft system can include an aircraft power source and at least first and second galley appliances operably coupled to the aircraft power source. The aircraft system can further include a controller operably coupled to the first and second galley appliances. The controller can be configured to receive a first power request from the first galley appliance and a second power request from the second galley appliance. The controller can be further configured to sort the first and second power requests and distribute power to the first and second galley appliances from the aircraft power source based on the sorting of the first and second power requests.

Abstract: A controller for a multi-level converter regulates the DC midpoint voltage of the multi-level converter by accounting, for the effect non-redundant switch states have on the DC midpoint current. The controller includes a DC bus regulator that monitors the DC output voltage and generates in response a commanded voltage vector. The duty cycle calculator is operably connected to receive the commanded voltage vector generated by the DC-bus regulator and to generate in response to the commanded voltage vector duty cycles associated with non-redundant switch states. The DC midpoint regulator is operably connected to receive the non-redundant duty cycles calculated by the duty cycle calculator and to generate in response a first midpoint current command that accounts for the effect the non-redundant switch states have on the midpoint current.

Abstract: A rectifier circuit includes an input terminal that receives an alternating-current signal, a first rectifier circuit that generates a first direct-current voltage from the alternating-current signal, a bias-voltage generating circuit that generates a bias voltage from the first direct-current voltage, and a second rectifier circuit that generates a second direct-current voltage from the alternating-current signal biased with the bias voltage.

Abstract: Systems, methods and devices for power generation systems are described. In particular, embodiments of the invention relate to the architecture of power conditioning systems for use with fuel cells and methods used therein. More particularly, embodiments of the present invention relate to methods and systems usable to reduce ripple currents in fuel cells.

Abstract: The present invention relates to a power supply device for supplying power to a load, preferably a LED, comprising a first circuitry (12) with an inverter unit (24) adapted to provide an AC voltage, preferably a rectangular voltage, and a resonant circuit (30) with a capacitance (32) and an inductance (34), a second circuitry (14) with a rectifier unit (42), a switch (64) and said load (60), said switch being adapted to switch said load on and off, a controller unit (16) adapted to control said switch (64) as to adjust the power provided to said load (60) without any measurement signal from said primary circuitry (12), and a transformer (18) with a primary side (20) and a secondary side (22), said primary side being connected to said first circuitry (12) and said secondary side (22) being connected to said second circuitry (14), preferably said rectifier, so that said first and second circuitries are galvanically isolated.

Abstract: Embodiments of the invention relate to a method and apparatus for a zero voltage processor sleep state. A voltage regulator may be coupled to a processor to provide an operating voltage to the processor. During a transition to a zero voltage power management state for the processor, the operational voltage applied to the processor by the voltage regulator may be reduced to approximately zero while an external voltage is continuously applied to a portion of the processor to save state variables of the processor during the zero voltage management power state.

Abstract: Provided is a contactless power receiving unit which has a simple configuration, and which is capable of generating constant induced electromotive force regardless of the orientation of a power receiving coil. Multiple power receiving coils are arranged to form certain relative angles to one another in a parallel magnetic field generated by a power supply unit. A rectifier circuit is connected to each power receiving coil. An adder circuit is configured to add DC power obtained, through the rectifier circuits, from the multiple power receiving coils, and to output resultant DC power of the addition.

Abstract: A power supply includes two or more input waveforms being shaped or selected so that after being separately level-shifted and rectified, their additive combination results in a DC output waveform with substantially no ripple. The power supply may comprise a waveform generator, a level conversion stage for step up or down conversion, a rectification stage, and a combiner. The waveform generator may generate complementary waveforms, preferably identical but phase offset from each other, such that after the complementary waveforms are level-converted, rectified and additively combined their sum will be constant, thus requiring no or minimal smoothing for generation of a DC output waveform. The level conversion may be carried out using transformers or switched capacitor circuits. Feedback from the DC output waveform may be used to adjust the characteristics of the input waveforms.

Abstract: A system for driving a motor includes first and second rectifier circuits, a direct current (DC) link circuit, an inverter circuit, a voltage booster circuit, and a switch control circuit. When the motor is at a deceleration state, a micro control unit (MCU) outputs a first charging signal to turn on a switch of a first relay and turn off a switch of a second relay, a regenerative current from the motor is charged into a storage capacitor. Before the motor is in an acceleration state, the MCU outputs a second charging signal to turn on the switch of the second relay and turn off the switch of the first relay, and turn on a boosting switch, an increased voltage of the storage capacitor is charged into another storage capacitor. When a voltage at the DC link circuit reaches a predetermined value, the MCU controls the inverter circuit to accelerate the motor.

Abstract: Choppers are provided respectively in the output stages of two diode bridges, and their output sides are connected in parallel to a smoothing capacitor. By controlling the operations of the two choppers, the currents which are allowed to be inputted to the diode bridges are made triangular waves of mutually opposite phases, or middle-phase waveforms of three phases.