Abstract: Apparatus and methods for supplying DC power to control circuitry of a matrix converter is provided. In certain embodiments, a matrix converter includes an array of switches having AC inputs for receiving a multi-phase AC input voltage and AC outputs for providing a multi-phase AC output voltage to a load, such as an electric motor. The matrix converter further includes control circuitry for opening or closing individual switches of the array, and a clamp circuit connected between the AC inputs and AC outputs of the array and operable to dissipate energy of the load in response to an overvoltage condition, such as an overvoltage condition arising during shutdown. The clamp circuit includes a switched mode power supply operable to generate a DC supply voltage for the control circuitry.

Abstract: An electronic circuit to receive input AC signals having different phases, and to control bidirectional switches corresponding to phases to generate, based on input AC signals having the phases, output AC signals having the phases and having a frequency different from a frequency of the input AC signals, the electronic circuit has reference signal circuitry to generate a reference signal having a frequency higher than the frequency of the output AC signals, and a commutation circuitry to control switching between voltage commutation and current commutation, wherein, in the voltage commutation, the commutation circuitry switches the bidirectional switches corresponding to the phases in sequence based on a voltage level of the output AC signals of the phases before and after a time point when an amplitude of the reference signal becomes a specific amplitude value, and in the current commutation, the commutation circuitry switches the bidirectional switches in parallel.

Abstract: A power supply control device according to one or more embodiments may be provided to: control a power conversion device that has a configuration in which a resonant circuit is provided on an output side of a matrix converter including switching circuits having snubber elements, and that performs AC-AC conversion of output from a multi-phase AC power supply. The power supply control device performs control such that: the output current, which has a phase difference caused by the resonant circuit, is negative during a period in which an absolute value of a positive-going output voltage that is output from the power conversion device increases while the output current is positive during a period in which the absolute value of a negative-going output voltage increases; and a polarity of the output current does not change within a period in which the snubber element is discharged.

Abstract: Provided is a method for generating a multiphase electrical alternating current having a sinusoidal fundamental wave in each phase by a multiphase inverter of a wind power installation. The multiphase inverter is controlled by a tolerance band method which respectively has an upper and a lower band limit for each of the phases of the inverter. The inverter has, for each phase, an upper switch for generating a positive sine half-wave of the alternating current of the phase and a lower switch for generating a negative sine half-wave of the alternating current of the phase. The method includes generating the positive sine half-wave by the upper switch and generating the negative sine half-wave by the lower switch based on the band limits of the phase, and changing at least one of the band limits such that a signal component superimposed on the respective sinusoidal fundamental wave is reduced.

Abstract: A method for adjusting an amplitude of a voltage injection of a rotating, multi-phase electric machine that is fed using a PWM-controlled inverter includes determining, at a first time, a predetermined current vector that would be present at the machine at a second time using a voltage equation of the machine based on a voltage predetermined in a controller for actuating the machine, a current vector determined from phase currents measured at the first time, and a speed of the machine. The method further includes determining a real current vector present at the machine at the second time based on phase currents of the machine measured at the second time and calculating a current vector difference between the predetermined current vector and the real current vector at the second time. The method further includes adjusting the amplitude of the voltage injection based on the calculated current vector difference.

Abstract: Systems and methods of fault tolerant power conversion include an inverter with a plurality of inverter phase legs. Each phase leg includes a positive switch, a negative switch, and a bi-directional midpoint switch. Redundant phase leg includes a positive redundant switch connected between the positive switches and the bi-directional midpoint switches. The redundant phase leg includes a negative redundant switch connected between the negative switches and the bi-directional midpoint switches. Upon detection of a fault condition in at least one switch of the plurality of inverted phase legs, one of the positive redundant switch and the negative redundant switch is closed to bypass at least one switch with the fault condition to maintain operation of the power converter.

Abstract: The inverter includes an inverting module including a plurality of switching elements, wherein the inverting module are configured for receiving a direct current (DC) stage voltage and for generating an output voltage of three-phases via switching of the switching elements. The device includes: a command voltage outputting unit configured for providing a pulse width modulation (PWM) control signal corresponding to an initial command voltage to the switching elements of the inverting module when the initial command voltage is within a voltage limit; a modulation index modifying unit configured for modifying a modulation index of the initial command voltage when the initial command voltage is outside the voltage limit; and an overmodulated command voltage generation unit configured for modifying the initial command voltage using the modified modulation index to form a modified command voltage and for limiting the modified command voltage to the voltage limit to generate an overmodulated command voltage.

Abstract: Increased DC-to-AC power conversion efficiency in a scalable, flexible, resilient, cascading inverter driver topology. Plural power cells, which include a rectifier and an inverter, are arranged in a series/parallel topology. Use of plural power cells increases efficiency by reducing voltage transition losses and by increasing duty cycle. Also, the power cells output AC to an electric motor using a forward-looking controller that responds to varying power demand while maintaining motor speed at a maximum efficiency level. Power output is varied by varying the width of rectifier output pulses to the inverters while maintaining pulse voltage. Transitions between power levels are smoothed by pulse density modulation. Pulse density, determined automatically in the inverter, begins high and gradually becomes less dense so voltage changes rapidly then slowing gradually. The topology and power cell components allow faulty power cells 10 to be isolated and bypassed.

Abstract: Apparatus and associated methods relate to controlling an electric field profile within a drift region of an LDMOS device using biased field plates to deplete majority carriers from a drift region between a body/drift-region metallurgical junction and a drain contact. Such field plates are located in trenches that longitudinally extend within the drift region. Field plates are laterally spaced apart from each other at a distance that permits substantial depletion of majority carriers between adjacent field plates. Trenches have trench bottoms located within a drift-region/substrate metallurgical junction so as to permit substantial depletion of majority carriers between trench bottoms and the drift-region/substrate metallurgical junction. Between adjacent trenches, dopant concentrations can be increased up to a threshold that can be substantially depleted under specified bias conditions.

Abstract: A converter having at least one converter module, which includes a primary circuit connected to a power supply, a secondary circuit connected to a load, and a DC link circuit having an intermediate circuit capacitance, is operated according to the disclosed method by controlling the primary circuit such that the intermediate circuit voltage dropping across the intermediate circuit capacitance is adjusted to a predetermined desired voltage value which depends on the direction of the power flow in the secondary circuit.

Abstract: A step-down AC/AC converter for use in an electric distribution system includes at least one chopper circuit for each one of a plurality of phases of the AC power, each chopper circuit including a four-quadrant switch coupled in series between primary and secondary sides of the chopper circuit and a current-bidirectional two-quadrant switch coupled between the secondary side of the chopper circuit and a common node. Each current-bidirectional two-quadrant switch is oriented in the same direction, with respect to the secondary side of the corresponding chopper circuit and the common node. The converter further includes a control circuit configured to pulse-width-modulate control inputs of the switches, to convert a first multiphase AC voltage at the primary sides of the chopper circuits to a second multiphase AC voltage at the secondary sides of the chopper circuits, the second multiphase AC voltage being lower in voltage than the first multiphase AC voltage.

Abstract: The present invention discloses a lossless snubber circuit and an operation method thereof. The lossless snubber circuit includes a first snubber circuit. The first snubber circuit includes a first diode (D7) and a capacitor (C3). The capacitance of the capacitor (C3) is big enough so that a voltage spike generated at the moment when a switch transistor (Q1) is turned off is depressed by charging the capacitor (C3). When the switch transistor (Q1) is on, the electric charges released by the capacitor (C3) are directed to a first capacitor (C1) in a three-phase Vienna structure, so as to avoid the problem of voltage stress difference caused by the large quantity of electric charges released by the capacitor (C3) flowing back to the switch transistor (Q1).

Abstract: Provided is a matrix converter including a power converter, a commutation controller, and a compensator. The power converter includes a plurality of bidirectional switches. The commutation controller performs one of a three-step commutation operation and a four-step commutation operation by the bidirectional switches as a switch source and the bidirectional switches as a switch destination when an input terminal to be connected to an output terminal is switched by on/off control of the bidirectional switches. The compensator compensates for an output voltage error generated when the input terminal to be connected to the output terminal is switched, based on a potential difference before and after the switching of the input terminal to be connected to the output terminal, an output current of the output terminal, and capacitance between input and output terminals of unidirectional switches.

Abstract: A matrix converter includes: a power convertor that includes a plurality of bidirectional switches; and a controller configured to control the plurality of bidirectional switches. The controller includes: a first commutation controller configured to perform a commutation control with a first commutation method; a second commutation controller configured to perform a commutation control with a second commutation method different from the first commutation method; and a selector configured to select a commutation controller that is configured to execute a commutation control from the first commutation controller and the second commutation controller based on any one of a phase of an output electric current from the power convertor and a phase of an input voltage to the power convertor.

Abstract: A matrix converter includes a power converter and a controller. The power converter includes bidirectional switches each having a controllable conducting direction. The bidirectional switches are disposed between input terminals and output terminals. The input terminals are respectively coupled to phases of an AC power source. The output terminals are respectively coupled to phases of a load. The controller controls the bidirectional switches. A first commutation controller performs commutation control when the conducting direction is unidirectional. A second commutation controller performs the commutation control when the conducting direction is bidirectional. A selector selects between the first commutation controller and the second commutation controller to perform the commutation control based on a state of an output current from the power converter.

Abstract: A matrix converter includes a power converter and a controller. The power converter includes bidirectional switches each having a conducting direction controllable by switching elements. The bidirectional switches are disposed between input terminals coupled to phases of an AC power source and output terminals coupled to phases of a load. A first commutation controller performs commutation control based on a first commutation. A second commutation controller performs the commutation control based on a second commutation. A selector selects between the first and second commutation controllers and to perform the commutation control based on a vector of an output current or an output voltage from the power converter or a vector of an input voltage or an input current from the AC power source to the power converter.

Abstract: A matrix converter according to an embodiment includes a voltage command corrector and a drive signal generator. The voltage command corrector corrects the magnitude of an output voltage command on the basis of amplitude variations of an input current from an AC power supply to a power converter, the amplitude variations being caused by a ripple component of the input current. The drive signal generator generates drive signals that turn ON/OFF a plurality of bidirectional switches on the basis of the output voltage command corrected by the voltage command corrector.

Abstract: A method of controlling a frequency converter comprises steps for measuring phase currents flowing in a three-phase supply network, for generating a first modulation space vector that comprises an angle that is synchronous to a supply voltage of the three-phase supply network and a determined modulation index as an amplitude, for generating a third modulation space vector depending on the first modulation space vector and the measured phase currents and for modulating the frequency converter according to the third modulation space vector.

Abstract: A matrix converter includes input terminals, output terminals, a power conversion circuit, and a snubber circuit. The power conversion circuit includes bidirectional switches of which each includes antiparallel connection circuits connected serially. The snubber circuit is connected to the bidirectional switches. The snubber circuit includes first diodes, a capacitor, a second diode, and third diodes. The first diodes are respectively corresponded to the bidirectional switches. A first connecting point of each the first diode is connected to a connection point between the two unidirectional switching elements constituting the bidirectional switch. A first connecting point of the capacitor is connected to a second connecting point of each the first diode. First and second connecting points of the second diode are connected to a second connecting point of the capacitor and the corresponding output terminal. The bidirectional switches, the first diodes, and the second diode are arranged in one power module.

Abstract: A matrix converter according to an embodiment includes a power converter having a plurality of bidirectional switches, a controller, and a current detector. The controller controls the power converter. The correct detector detects a current flowing to an output side of the power converter. The controller extracts a high-frequency component contained in the current detected by the current detector, adjusts an output current reference on the basis of the high-frequency component, and controls the power converter on the basis of the adjusted output current reference.

Abstract: Provided is a matrix converter including a power converter, a commutation controller, and a compensator. The power converter includes a plurality of bidirectional switches. The commutation controller performs one of a three-step commutation operation and a four-step commutation operation by the bidirectional switches as a switch source and the bidirectional switches as a switch destination when an input terminal to be connected to an output terminal is switched by on/off control of the bidirectional switches. The compensator compensates for an output voltage error generated when the input terminal to be connected to the output terminal is switched, based on a potential difference before and after the switching of the input terminal to be connected to the output terminal, an output current of the output terminal, and capacitance between input and output terminals of unidirectional switches.

Abstract: A method and apparatus are provided for operating a converter circuit, which includes n input phase connections and p output phase connections, where n?2 and p?2, and (n·p) two-pole switching cells for switching at least one positive and negative voltages between the poles. Power semiconductor switches of the switching cells are driven a drive signal. To reduce undesired circulating currents and adjust the mean voltage deviation of capacitive energy storage of all the switching cells to zero, an inductance is connected into each series connection, with a switching cell together with an inductance in each case forming a phase module. For each phase module, the drive signal is formed from a reference signal based on the voltage across the phase module and from a voltage signal across the inductance. The voltage signal is formed from an intermediate setpoint value of the current through the phase module.

Abstract: An apparatus is provided. A differential pair of transistors is configured to receive a first differential signal having a first frequency, and a transformer, having a primary side and a secondary side is provided. The primary side of the transformer is coupled to the differential pair of transistors, and the secondary side of the transformer is configured to output a second differential signal having a second frequency, where the second frequency is greater than the first frequency. A first transistor is coupled to the first supply rail, the primary side of the transformer, and the differential pair of transistors, where the first transistor is of a first conduction type. A second transistor is coupled to the second supply rail, the primary side of the transformer, and the differential pair of transistors, where the second transistor is of a second conduction type.

Abstract: An apparatus is provided. A differential pair of transistors is configured to receive a first differential signal having a first frequency, and a transformer, having a primary side and a secondary side is provided. The primary side of the transformer is coupled to the differential pair of transistors, and the secondary side of the transformer is configured to output a second differential signal having a second frequency, where the second frequency is greater than the first frequency. A first transistor is coupled to the first supply rail, the primary side of the transformer, and the differential pair of transistors, where the first transistor is of a first conduction type. A second transistor is coupled to the second supply rail, the primary side of the transformer, and the differential pair of transistors, where the second transistor is of a second conduction type.

Abstract: An electronic circuit comprising a direct current interface at which a direct current is providable, an alternating current interface at which an alternating current is providable, a set of switchable half-bridges coupled to the direct current interface, each half-bridge comprising two blocks each having a switch and a diode, a control entity configured for switching the switches of the half-bridges with a predefined relative phase shift between different half-bridges, and a filter entity arranged between the alternating current interface and a plurality of parallel paths relating to the plurality of half-bridges wherein the filter entity comprises a coupled inductor inductively coupling the plurality of parallel paths.

Abstract: Systems and methods are provided for delivering energy using an energy conversion module. An exemplary method for delivering energy from an input interface to an output interface using an energy conversion module coupled between the input interface and the output interface comprises the steps of determining an input voltage reference for the input interface based on a desired output voltage and a measured voltage at the output interface, determining a duty cycle control value based on a ratio of the input voltage reference and the measured voltage, operating one or more switching elements of the energy conversion module to deliver energy from the input interface to the output interface with a duty cycle influenced by the duty cycle control value.

Abstract: Systems and methods are provided for delivering energy from an input interface to an output interface. An electrical system includes an input interface, an output interface, an energy conversion module between the input interface and the output interface, an inductive element between the input interface and the energy conversion module, and a control module. The control module determines a compensated duty cycle control value for operating the energy conversion module to produce a desired voltage at the output interface and operates the energy conversion module to deliver energy to the output interface with a duty cycle that is influenced by the compensated duty cycle control value. The compensated duty cycle control value is influenced by the current through the inductive element and accounts for voltage across the switching elements of the energy conversion module.

Abstract: Method for operating an ac/ac converter circuit for a high-frequency-link converter. The ac/ac converter circuit converts an ac input voltage to an ac output voltage. When the ac input voltage is zero, each of a pair of switches for both first and second arms are caused to be on. Current flows through the first arm along a first direction and through the second arm along a second, opposite direction. Next, when the ac input voltage is zero, a selected switch in the second arm is caused to be turned off. The position of the switches can be maintained as the ac input voltage transitions to a dc level, reaches the dc level, approaches zero, and again reaches zero. When the ac input voltage again reaches zero, the selected switch for the second arm is caused to be turned on.

Abstract: Systems and methods are provided for delivering energy using an energy conversion module that includes one or more switching elements. An exemplary electrical system comprises a DC interface, an AC interface, an isolation module, a first conversion module between the DC interface and the isolation module, and a second conversion module between the AC interface and the isolation module. A control module is configured to operate the first conversion module to provide an injection current to the second conversion module to reduce a magnitude of a current through a switching element of the second conversion module before opening the switching element.

Abstract: A power supply includes a power source having at least one power source output, and a plurality of drivers connected to the at least one power source output. At least one of the plurality of drivers includes a bridge network having a first switch, a second switch and a bridge network output. The first switch is connected between the at least one power source output and the bridge network output. The second switch is connected between the bridge network output and a ground. The bridge network further includes at least one control input connected to the second switch. The bridge network is adapted to change a state of the first switch based on a state of the second switch.

Abstract: A power supply includes multiple power cells and a master control system in communication with each of the power cells. The master controller includes a control processor configured to receive power cell control information and a host in communication with the control processor wherein the host is configured to receive command and status information.

Abstract: A control device for a matrix converter includes an input voltage detector, an output current detector, a pulse width modulator, and an input voltage command calculator. The input voltage detector is configured to detect an input voltage of the matrix converter. The output current detector is configured to detect an output current of the matrix converter. The pulse width modulator is configured to generate a PWM pulse command signal by using the input voltage, the output current, and an output line voltage command. The input voltage command calculator is configured to calculate an input voltage command of the matrix converter.

Abstract: Power conversion systems are presented with common mode reduction by space vector pulse width modulation zero vector selection to counteract common mode contribution of active vectors.

Abstract: A power conversion device includes a main circuit that has switches connecting each phase of a three-phase AC power supply to each output phase, an LC filter having a reactor and a capacitor connected between the three-phase AC power supply and each bidirectional switch, and a current detector detecting an input current or a load current, and a four-step commutation device generating four steps on the basis of the polarity of the load current. The four-step commutation device sets times between the steps to a value more than zero so as to inhibit open circuit between output phases and short circuit between power supply phases, and sets the times between the steps in accordance with the polarity of the load current so as to cancel a distortion of an output voltage due to four-step commutation during a PWM cycle.

Abstract: A method for operating a matrix converter to convert n phases of a generator into alternating voltage with nr (nr<n) phases of a load connected to a network includes the steps of alternatingly connecting the nr phases of the load using a plurality of controllable bi-directional switches disposed in an (n×nr) matrix, wherein nr phases of the generator are always connected with the load and (n?nr) phases of the generator are not connected with the load, and controlling the switching of a phase k of the generator at a time t to a phase c of the grid, using a periodical, continuous, segmented function k(t). The function k(t) defines a broken line having a plurality of segments, wherein each segment i is defined by a starting time ti and a pulsation ?i, and the value of the function k(t) is rounded to the closest integer value.

Abstract: A frequency converter includes a first pair of transistors including first and second transistors, a second pair of transistors including third and fourth transistors, and a variable impedance circuit. The first transistor includes source terminal being connected to positive-phase input terminal, drain terminal being connected to positive-phase output terminal, and gate terminal being supplied with positive-phase local signal. The second transistor includes source terminal being connected to positive-phase input terminal, drain terminal being connected to negative-phase output terminal, and gate terminal being supplied with negative-phase local signal. The third transistor includes source terminal being connected to negative-phase input terminal, drain terminal being connected to positive-phase output terminal, and gate terminal being supplied with negative-phase local signal.

Abstract: An adjustable frequency generator for a power supply is disclosed. The adjustable frequency generator comprises a waveform generator, a voltage generator and a comparator. The waveform generator is used for generating a saw wave. The voltage generator is used for generating a variable upper reference voltage and a variable lower reference voltage according to variation of a load. The comparator is coupled to the waveform generator and the voltage generator and used for comparing the saw wave with the variable upper reference voltage and the variable lower reference voltage and generating an output signal. A frequency of the output signal decreases when the load becomes lighter.

Abstract: A power supply includes a power source having at least one power source output, and a plurality of drivers connected to the at least one power source output. At least one of the plurality of drivers includes a bridge network having a first switch, a second switch and a bridge network output. The first switch is connected between the at least one power source output and the bridge network output. The second switch is connected between the bridge network output and a ground. The bridge network further includes at least one control input connected to the second switch. The bridge network is adapted to change a state of the first switch based on a state of the second switch.

Abstract: Circuit topologies and control methods for a power converter and are described.

Abstract: A control device for a matrix converter includes an input voltage detector, an output current detector, a pulse width modulator, and an input voltage command calculator. The input voltage detector is configured to detect an input voltage of the matrix converter. The output current detector is configured to detect an output current of the matrix converter. The pulse width modulator is configured to generate a PWM pulse command signal by using the input voltage, the output current, and an output line voltage command. The input voltage command calculator is configured to calculate an input voltage command of the matrix converter.

Abstract: An output voltage command signal for outputting a specified three-phase ac output voltage is generated by a line voltage control command signal generating section, and a signal representing a current flow ratio is generated by a current flow ratio generating section based on a specified input current command signal. The output voltage command signal is corrected by a command signal computing section based on the output voltage command signal generated by the line voltage control command signal generating section and the signal representing the current flow ratio generated by the current flow ratio generating section. A PWM conversion signal is generated by a PWM conversion signal generating section based on the corrected output voltage command signal and a carrier signal. Based on the generated PWM conversion signal, a three-phase ac input voltage is converted into a specified three-phase ac input voltage by a conversion section.

Abstract: A method for mitigating aliasing effects in a single phase power converter and mitigating aliasing effects and inhibiting thermal run-away in a multi-phase power converter at varying load transition rates. A single phase or multi-phase power converter having an on-time is provided and the frequency of the power converter is adjusted so that a load step period and the on time of the single phase power converter are in a temporal relationship. Alternatively, a load step rate is inhibited from locking onto a phase current of the single phase power converter by suspending an oscillator signal. In accordance with another alternative, a load step rate is inhibited from locking onto a phase current of the single phase power converter by suspending an oscillator signal and dithering an input signal to the oscillator.

Abstract: A control method for a PWM cyclo-converter is provided in which a voltage can be accurately generated even when a voltage command is small. In the PWM cyclo-converter, the turning on and off operations of two-way semiconductor switch are repeated at intervals of short time. As switching patterns, within the intervals of short time, a first terminal of output side terminals outputs in order a maximum potential phase P, an intermediate potential phase M and the maximum potential phase N, a second terminal of the output side terminals outputs in order the maximum potential phase P, the intermediate potential phase M, a minimum potential phase N, the intermediate potential phase M and the maximum potential phase P, and a third terminal of the output side terminals outputs in order the intermediate potential phase M, the minimum potential phase N and the intermediate potential phase M.

Abstract: A power supply includes a power source having at least one power source output, and a plurality of drivers connected to the at least one power source output. At least one of the plurality of drivers includes a bridge network having a first switch, a second switch and a bridge network output. The first switch is connected between the at least one power source output and the bridge network output. The second switch is connected between the bridge network output and a ground. The bridge network further includes at least one control input connected to the second switch to direct electrical current from the at least one power source output either substantially through the bridge network output or through the second switch to ground.

Abstract: A method for thermal protection of a frequency converter and a frequency converter includes means for controlling the output current of the frequency converter. The method includes the steps of determining predetermined data points which define a thermal current limit for a semiconductor component of the frequency converter at specific temperatures at plural switching frequencies, and determining predetermined data points which define a thermal current limit for the semiconductor component at specific temperatures at a zero converter output frequency. The method also includes determining the highest allowable thermal current as a function of a measured temperature, a determined switching frequency, and a determined output frequency based on the defined data points, and limiting the output current of the frequency converter to the determined highest allowable thermal current.

Abstract: An electric power converter, electric power conversion system and method that, without using a DC-DC converter, uses and allots the electric power of plural power sources while reducing the volume and losses. At least one phase of the motor is connected to plural power sources and generates and synthesizes pulses from output voltages of plural power sources so as to drive the multi-phase AC motor. A different phase of the motor is connected to one DC power source and generates pulses from the output voltage of the power source so as to generate a driving voltage for the multi-phase AC motor. This arrangement allows use/allotment of the power of plural power sources with a reduced number of semiconductor components.

Abstract: The parallel multiplex matrix converter couples in parallel at least two matrix converters, each of which PWM-controls bidirectional switches coupling input phases from an AC power supply to each output phases so as to output an arbitrary AC voltage or DC voltage. The output sides of the matrix converters are directly coupled in parallel to each other without any reactor. The input sides of the matrix converters use reactors inserted between the input phases from the AC power supply and the AC power supply at each of the respective matrix converters coupled in parallel.

Abstract: A method includes controlling the cyclo-converter 7 in coordination with controlling a coupled HF inverter 3. The controlling of the cyclo-converter 7 provides at least a first freewheeling FW period in the cyclo-converter for each cycle of the HF inverter 3. The controlling of the HF inverter provides a freewheeling period in the HF inverter 3 each time the first freewheeling period is provided in the cyclo-converter.

Abstract: It is an object of the present invention to provide a PWM cycloconverter that can compensate an error between a voltage command and a real voltage generated by a commuting operation. The PWM cycloconverter for solving the above-described problem includes: an input voltage phase detector (6) for detecting the phase of the voltage of a three-phase ac power source (1); a current direction detector (7) for detecting the direction of a current supplied to a two-way semiconductor switch (3); and a commutation compensator (11) for receiving the outputs of the input voltage phase detector and the current detector as inputs to compensate for a voltage command.

Abstract: The present invention provides a bi-directional field effect transistor and a matrix converter using the same, in which a current flowing bi-directionally can be controlled by means of a single device. The bi-directional field effect transistor includes: a semiconductor substrate 1; a gate region which is arranged on the semiconductor substrate 1, with a channel parallel to a principal surface of the substrate 1 and a gate electrode 13a for controlling conductance of the channel; a first region which is arranged on a first side of the channel; and a second region which is arranged on a second side of the channel; wherein a forward current which flows from a first electrode 11a of the first region through the channel to a second electrode 12a of the second region and a backward current which flows from the second electrode 12a through the channel to the first electrode 11a can be controlled by a gate voltage applied to the gate electrode 13a.