Abstract: An induction machine with localized voltage unbalance compensation is disclosed. The use of an induction machine with a voltage unbalance correction compensator (VUC) may be used to maintain proper working conditions of the machine during intervals of voltage unbalance.

Abstract: A motor controller 100-1 includes an inverter, a current detection unit, a current detector, and a PWM signal generator.

Abstract: An arrangement provides an AC current to a load for direct electrical heating. The arrangement includes a AC-DC-AC converter cell. The converter cell has at least two converter input terminals connected to at least two transformer output terminals. The converter cell has a first converter output terminal and a second converter output terminal, wherein the first converter cell output terminal is adapted to be connected to the load.

Abstract: A three-phase regenerative drive configured for operation from a single phase alternating current (AC) power source, the three-phase regenerative drive including a three-phase converter having inputs for connection to a single-phase AC source, the three-phase converter having three phase legs, a three-phase inverter for connection to a motor, the three phase inverter configured to provide three phase command signals to the motor, and a DC bus connected between the three-phase converter and the three-phase inverter. A first phase leg of the three-phase converter and a second phase leg of the three-phase converter are employed to direct current from the single-phase AC source to the DC Bus and a third phase leg of the three phase legs of the three-phase converter returns current to a return of the AC source.

Abstract: A six-wire three-phase motor that can realize both of increasing an output and reducing a torque ripple is provided. A six-wire three-phase motor is a six-wire three-phase motor including: a stator including a winding wire wound independently between phases; and a rotor including a plurality of magnets in a circumferential direction, wherein the stator or the rotor is configured in such a manner that a third harmonic current component in a motor current of when an overmodulation voltage based on a PWM signal is applied becomes higher than a third harmonic current component in a motor current of when a sinusoidal modulation voltage based on the PWM signal is applied.

Abstract: In one embodiment, a vehicle pre-charge limiting system is disclosed. The system includes an inverter, a comparator, a latch circuit, and a microprocessor. The inverter inverts a first power signal into a second power signal. The comparator receives a first measured current of the second power signal and compares the first measured current to a predetermined current value. The comparator transmits a first control signal indicative of the first measured current exceeding the predetermined current value. The latch circuit transmits a second control signal to the inverter to discontinue inverting the first power signal and transmits a first latch signal. The microprocessor receives a first sense signal indicative of current of the first power signal and transmits a third control signal to the latch circuit. The microprocessor inverts the first power signal into the second power signal for a predetermined number of output periods.

Abstract: An electronic device and a power supply method thereof are provided. The electronic device includes a plurality of power terminals, a plurality of bridge rectifiers, a detector, a power supply circuit, and a basic device. The detector detects current directions of currents flowing through the power terminals. The power supply circuit is electrically coupled to the power terminals through the bridge rectifiers. The basic device obtains power from the power supply circuit. At least two of the power terminals are selectively electrically coupled to an external power line. The power supply circuit supplies power to the basic device from the external power line through the bridge rectifiers. The basic device controls the power supply circuit according to the current directions of the at least two of the power terminals electrically coupled to the external power line, so as to output power between another at least two of the power terminals.

Abstract: An apparatus for controlling an inverter for a motor driving includes: a current controller configured to generate a d/q-axis voltage reference for allowing a d/q-axis current detection value, which is obtained by measuring a current supplied from the inverter to the motor, to converge on the d/q-axis current reference for driving the motor, and a voltage modulator configured to control switching of the inverter by selectively applying one among a plurality of predetermined pulse width modulations (PWM) based on a point at which the d/q-axis voltage reference is located in a hexagonal space voltage vector diagram.

Abstract: A motor drive apparatus includes a PWM converter configured to convert AC power of an AC power supply into DC power, a DC link unit including capacitors provided on the DC output side of the PWM converter and connected in series with each other, an inverter configured to convert the DC power of the DC link unit into AC power for driving a motor and output the AC power, a DC link voltage detection unit, a power supply voltage detection unit, a short-circuit judgment unit configured to judge that at least one of the capacitors has shorted when the DC link voltage value is smaller than the peak value of the power supply voltage, and a shut-off unit configured to shut off flow of AC power from the AC power supply into the PWM converter when the short-circuit judgment unit judges that at least one of the capacitors has shorted.

Abstract: Provided is a power conversion device including: a step-up converter unit, including a reactor to which a DC voltage is to be input, a switching element connected to the reactor in parallel, and a backflow prevention element connected to the reactor in series; a smoothing capacitor configured to smooth an output voltage from the step-up converter unit; an inverter unit configured to convert the output voltage smoothed in the smoothing capacitor into an AC voltage; a dew condensation state detection unit configured to detect a state of dew condensation, which occurs due to a cooler configured to cool the step-up converter unit and the inverter unit; and a control unit configured to control an operation of the step-up converter unit, wherein the control unit includes: a determination unit configured to determine the state of dew condensation detected by the dew condensation state detection unit; and a step-up control unit configured to control a step-up operation of the step-up converter unit based on a result

Abstract: According to one embodiment, when an effective value of an input current flowing into a booster circuit rises to a value greater than or equal to a second set value, boosting of the booster circuit is started and, after the start, when the effective value lowers to a value lower than a first set value lower than the second set value, boosting of the booster circuit is stopped. Then, if the three-phase AC source is in an unbalanced state, the first set value is set to a value lower than usual.

Abstract: A power converter includes: a plurality of external terminals; a grounded earth terminal; a power conversion circuit; a ground conductor; and a plurality of inductors. A plurality of nodes of the power conversion circuit are connected to the respective plurality of external terminals. The power conversion circuit performs power conversion by switching received power. A plurality of inductors are inserted between the plurality of external terminals and the plurality of nodes. Further, another inductor is inserted between the ground conductor and the earth terminal. In this way, there can be provided a power converter that provides a sufficient noise reduction effect also in a high frequency region.

Abstract: When a rectifying duty dr, a discharge duty dc, a voltage between both ends Vc of a capacitor, and a rectified voltage Vrec of an AC voltage are introduced, a virtual DC link voltage in an inverter is expressed by dc·Vc+dr·Vrec. The discharge duty is a time ratio at which a switch is conductive. The rectifying duty has a value obtained by subtracting the discharge duty and a zero voltage duty from 1. The zero voltage duty is a time ratio at which the inverter adopts a zero voltage vector irrespective of the magnitude of a voltage output from the inverter. In a boost chopper, the capacitor is charged during a part of a period during which the virtual DC link voltage is greater than the rectified voltage.

Abstract: Apparatus to provide bypass redundancy for a multiphase multilevel inverter including a spare inverter stage and a switch circuit to connect the spare inverter stage between a selected one of the inverter phase first nodes having a bypassed stage and a common connection node, and to connect the remaining inverter phase first nodes with the common connection node.

Abstract: A power supply detecting circuit includes a first voltage detecting module configured to detect an input voltage of a power supply module; a micro control unit (MCU) connected to the first voltage detecting module; a display module connected to the MCU; a second voltage detecting module configured to detect an output voltage of the power supply module; and a current detecting module configured to detect an output current of the power supply module. The MCU is capable of comparing the detected input voltage, the detected output voltage, and the detected output current of the power supply module with corresponding predetermined parameters and calculating an output power of the power supply module. The display module is capable of displaying the detected input voltage, the detected output voltage, the detected output current, and the output power of the power supply module.

Abstract: A method for controlling a variable speed wind turbine generator is disclosed. The generator is connected to a power converter comprising switches. The generator comprises a stator and a set of terminals connected to the stator and to the switches of the power converter. The method comprises: determining a stator flux reference value corresponding to a generator power of a desired magnitude, determining an estimated stator flux value corresponding to an actual generator power, determining a difference between the determined stator flux reference value and the estimated stator flux value, and operating said switches in correspondence to the determined stator flux reference value and the estimated stator flux value to adapt at least one stator electrical quantity to obtain said desired generator power magnitude.

Abstract: A method for operating an inverter which is connected to an energy supply grid via a transformer for feeding in electrical energy into the energy supply grid, includes measuring output currents and output voltages of the inverter, and actuating power switches of the inverter using actuation signals that are generated as a function of the measured output currents and the measured output voltages at a fundamental frequency of the energy supply grid. The actuation signals are further generated as a function of a harmonic component of the measured output voltages of the inverter at a multiple of the fundamental frequency using a control loop with positive feedback.

Abstract: The invention relates to a variable rotor speed wind turbine transmitting AC electric power to a utility grid. The wind turbine includes at least one AC generator and at least two power electronic converter units. Further, it includes means for transforming at least one nominal output value of the generator to at least one different nominal input value of the at least two power electronic converter units. The invention also relates to a wind park and a method of transmitting AC electric power to a utility grid from a variable rotor speed wind turbine as well as a method of servicing or inspecting a variable rotor speed wind turbine.

Abstract: An integrated circuit device comprising at least one analog to digital converter. The at least one ADC comprises at least one input operably coupled to at least one external contact of the integrated circuit device. The integrated circuit device further comprises detection circuitry comprising at least one detection module. The at least one detection module being arranged to receive at a first input thereof an indication of a voltage level at the at least one input of the at least one ADC, compare the received indication to a threshold value, and if the received indication exceeds the threshold value, output an indication that an excessive voltage state at the at least one input of the at least one ADC has been detected.

Abstract: Cascade H-Bridge inverters and carrier-based level shift pulse width modulation techniques are presented for generating inverter stage switching control signals, in which carrier waveform levels are selectively shifted to control THD and to mitigate power distribution imbalances within multilevel inverter elements using either complementary carrier or complementary reference modulation techniques.

Abstract: A matrix converter includes first to third AC reactors connected in series with first- to third-phase outputs of three-phase AC electric power, and a first cooling fan that generates cool air for cooling the first to third AC reactors. The first to third AC reactors are arranged side-by-side in a direction intersecting a direction in which the cool air flows.

Abstract: A railway power conditioner includes a DC-AC converter and a AC-DC converter for performing power conversion between AC power and DC power, a DC bus connected between the DC-AC converter and the AC-DC converter; a single-phase isolation transformer coupled to an output of the AC-DC converter and a coupling capacitor connected to the DC-AC converter.

Abstract: An energy generation system includes an inverter for converting a DC voltage into an AC voltage, a three-phase/two-phase transformer for transforming an output of the inverter into a three-phase/two-phase stationary coordinate system, a phase locked loop for calculating the phase and frequency of an output voltage of the inverter, a phase shifter for generating a current phase reference value, a current reference coordinate transformer for transforming the current phase reference value and the current amplitude reference value into a two-phase stationary coordinate system, a current phase calculator for outputting a current phase calculation value, a current phase calculator for outputting a current amplitude calculation value, a current adjuster for generating a current adjustment signal, an output three-phase transformer for transforming the current adjustment signal into a current adjustment signal in a three-phase stationary coordinate system, and a PWM controller for outputting a PWM control signal.

Abstract: The AC converter converts a single-phase input AC voltage with a frequency f0 into a three-phase output AC voltage with a frequency f1 that is lower than f0. The AC converter includes a switching section 101 with multiple switching elements and a switching control section 103 that controls the conduction states of the respective switching elements. The switching control section 103 supplies pulses that have been subjected to a pulse density modulation based on space vector modulation to the switching section 101, thereby getting the conversion into a three-phase output AC voltage done.

Abstract: A voltage source inverter comprises a zigzag transformer providing a neutral point. A rectifier unit comprises three single phase boost converters each connected to one of the three phases of AC power and the neutral point and comprising a bridge rectifier converting single phase AC power to DC power and using a boost inductor with a boost switch and blocking diode to develop a DC output. An inverter receives DC power and converts DC power to AC power. A link circuit is connected between each boost converter DC output and the inverter circuit and comprises a DC bus having first and second rails to provide a relatively fixed DC voltage for the inverter and a DC bus capacitance across the first and second rails to smooth voltage ripple. A switch controller controls operation of the boost switches using average current control for each of the boost converters.

Abstract: The present invention relates to an electric device for driving mechanical equipment comprising an alternating current motor and an inverter, the said inverter comprising, for each phase of the said motor, an H bridge structure comprising four switching elements distributed over two branches connecting two terminals of the said H bridge structure and intended to supply the winding of the said at least one phase of the motor, the said winding being a winding with a mid point and the said electric device being characterized in that it also comprises, for each phase of the said motor, an energy storage unit, in particular a supercondenser, connected, on the one hand, to the mid point of the winding of the concerned phase of the motor and, on the other hand, to a terminal of the H bridge structure supplying the said winding.

Abstract: A device for connecting at least one single-phase power supply line which, in particular, feeds the overhead line of a railroad track, to a three-phase power supply network. A primary side of a transformer is connected to the power supply network and a secondary side is connected to the single-phase power supply line and to a ground connection. A symmetry device is connected to a phase of the transformer, to the ground connection, and to the single-phase power supply line.

Abstract: The disclosure discloses an electric energy conversion device and system, to solve the problems of severe harmonic pollution, low power factor during the electric energy feedback from a power generation device to a power grid in the conventional art. The electric energy conversion device comprises: a plurality of single-phase rectifier bridge circuits, a first input ends of the a plurality of single-phase rectifier bridge circuits, and a second input ends of the a plurality of single-phase rectifier bridge circuits, wherein two input ends of each three-phase fully-controlled bridge circuit are connected with two output ends of each the rectifier bridge circuit respectively. Through the technical solution of the disclosure, the waveform coefficient of the current of the power generation device is improved, the harmonic wave is reduced, and the power factor is improved.

Abstract: A current control circuit (active element) is provided that is connected between a rectifier of a DC power source and a smoothing capacitor in a power frequency converter and that controls a variation in the rectified current caused by a variation in the instantaneous power consumption of the load device. When the rectified current increases, the current control circuit limits the current to have a reference current value or lower and, when the rectified current decreases, the current control circuit increases the current to have a value close to the reference current to thereby suppress the rectified current from the rectifier to a substantially-constant value. This consequently mitigates the influence on the primary power source by the variation in the instantaneous power consumption of the load device, thus clearing the Load Demand Variation specification required for the power source to be used in an aircraft.

Abstract: Three resonance-based universal power converter topologies are disclosed. One includes a partially resonant parallel L-C link and incorporates intermediate cross-over switching circuits between the link stage and each of the input and output stages (which are constructed using unidirectional switches), thereby permitting the partially resonant circuit to be operated bi-directionally. A second includes a partially resonant series LC link in parallel with the input and output networks. A third includes a partially resonant series LC link in series between the input and output networks. The input and output networks can be formed from either bidirectional switches or a combination of unidirectional switches and intermediate cross-over switching circuits, permitting the partially resonant circuit to be operated bi-directionally.

Abstract: A resonant circuit inverter with a rectifier, a DC link circuit and an inverter including controllable switches. The resonant circuit inverter has a first control means, with which the operating point (Ap) of the resonant circuit inverter determined by a phase angle between an output current (Iist) and a voltage (Uist) at the output of the resonant circuit inverter is controlled. The first control means determines frequency of the output current (Iist). The resonant circuit inverter has a phase detector for determining an actual phase angle as a function of a zero crossing of the output current (Iist). The resonant circuit inverter has means for detecting a zero crossing of the output current (Iist). For determining the actual phase angle, the difference (Ti?Tt) is determined from measured time (Ti) and a known dead time (Tt).

Abstract: There is provided a method of customizing an audio presentation for tailoring to a predetermined event sequence, one embodiment comprising identifying the predetermined event sequence from a predetermined event sequence database, associating a first audio asset with one or more selected events of the predetermined event sequence, synchronizing the timing of the first audio assets with the timing of the selected events, and linking the first audio assets to produce a customized audio presentation tailored to the predetermined event sequence. In one embodiment, the method includes downloading an interactive audio presentation content including an interactive audio presentation program, an audio assets database, and the predetermined event sequence database to a client computer. In one embodiment, a system for customizing an audio presentation tailored to a predetermined event sequence comprises a client computer, a client memory located on the client computer, and interactive audio presentation content.

Abstract: A controller device and corresponding method for modifying an AC input power to provide a reduced power AC output power to a load when coupled to the controller device. The AC output power has a series of cut-out pulses in half cycles of the AC output power waveform. The device includes a switching system having a plurality of switching elements for positioning the series of cut-out pulses in the half cycles of a waveform of the AC input power to result in said reduced power AC output power; and a switch control system for coordinating opening and closing of the plurality of switching elements during positioning of the series of cut-out pulses. The switch control system includes a synchronization system for synchronizing the switching system with timing of said half cycles of the AC input power waveform; wherein the series of cut-out pulses includes at least two cut-out pulses having different durations and different positioning in said half cycles.

Abstract: A method of controlling a plurality of power converters 1a, 1b and 1c can be used to interface to a supply network, ac busbar etc. Each power converter includes a network bridge 14 operating in accordance with a pulse width modulation (PWM) strategy having the same switching period and which causes at least one unwanted harmonic in the supply network voltage. The method includes the step of providing the switching period of the PWM strategy of each network bridge with a different time offset relative to a time datum such that the at least one unwanted harmonic in the supply network voltage is at least partially cancelled. Two alternative ways of providing the time offset are described.

Abstract: A method of controlling an uninterruptible power supply apparatus (UPS) is provided. The UPS apparatus includes at least an AC input voltage, a DC input voltage and a single-phase AC/AC converter. The single-phase AC/AC converter includes an AC inductor, a bus capacitor, a boost arm, a common arm and a buck arm. The method includes steps of: controlling the bus voltage to have a DC component and full-wave rectifying component, and setting a bus voltage parameter K so that the bus voltage approaches to a full-wave rectifying voltage when K approaches to 1, wherein 0?K?1.

Abstract: A circuit 1 for controlling the supply of electrical power to an induction coil 2, in particular to an induction coil 2 for heating a shrink attachment for tools, comprises a rectifier 3, having an input 3a, 3b, 3c for feeding an input power, and a rectifier output. The circuit 1 furthermore comprises an inverter 5 for putting out an AC-voltage, having an input and an inverter output 5a, 5b for connecting the induction coil 2, an intermediary circuit 4 for connecting the rectifier 3 with the inverter 5, and a regulation unit for regulating the power supplied to the induction coil 2. A measurement apparatus 6 for measuring a voltage A2 as an input variable for the regulation unit is connected to the output side of the inverter 5. A respective method for regulating the power supplied to the induction coil 2 comprises a regulation step, in which the current A2 supplied to the induction coil 2 is used as an input variable for the regulation of the power supplied to the induction coil 2.

Abstract: A static converter includes a current converter on the three-phase side and a current converter on the single-phase side, which are electrically conductively linked to one another on the DC voltage side, and which are respectively electrically conductively connected on the AC voltage side to a feeding three-phase network and a single-phase receiving network. According to an embodiment of the invention, one network-commutated current converter is provided as the current converter on the three-phase side, wherein the current converter on the single-phase side has two phase modules which are connected in parallel on the DC voltage side and whose current converter branches each have at least one two-pole subsystem. This results in a static converter which is simpler and costs less than a known static converter.

Abstract: A multi-lamp backlight apparatus is disclosed. The multi-lamp backlight apparatus includes 2N lamps, N balancing transformers, and a high-voltage power source. N is a positive integer and k is an integer index ranging from 1 to N. The kth balancing transformer among the N balancing transformers includes a first primary winding, a second primary winding, and a secondary winding. The first primary winding connects in series with the (2k?1)th lamp of the 2N lamps. The second primary winding connects in series with the first primary winding and the (2k)th lamp. The secondary winding corresponds to the first primary winding and the second primary winding. The high-voltage power source is connected between the first primary windings and the second primary windings.

Abstract: A semiconductor module has switching semiconductor elements connected in parallel to each other and at least a free wheeling semiconductor element reversely connected in parallel to the switching semiconductor elements. The free wheeling semiconductor element is placed between the switching semiconductor elements. At both end parts of the semiconductor elements, each of the switching semiconductor elements is placed. A longitudinal side of each of the switching semiconductor elements and the free wheeling semiconductor element is placed in parallel to a short side of the semiconductor module. An electric-power conversion device has a plurality of arms. Each arm is composed of the semiconductor elements.

Abstract: A voltage-sourced High-Voltage Direct Current (HVDC) apparatus, which converts 3-phase AC voltage from a 3-phase AC power source into high voltage DC through a rectifier including switching elements, is provided. In the apparatus, a rectifier controller receives detected 3-phase currents, apparent power, and active power and generates D and Q-axis signals. A D/Q controller receives the signals and generates active power D-axis signal and apparent power Q-axis signal. A PWM unit generates PWM on/off signals for turning on/off the switching elements based on output signals from the D/Q controller. The D/Q controller includes a rotary converter to convert the D and Q-axis signals into AC signals and D and Q-axis order units coupled thereto, and generates the D and Q-axis signals through the order units. The PWM unit converts the D and Q-axis signals into 3-phase AC signals and compares them with 3-phase triangular waves to generate on/off signals for turning on/off the switching elements.

Abstract: Disclosed are an apparatus and a method for controlling driving of a lamp. The apparatus for controlling driving of a lamp includes a plurality of lamps, a switching module for switching supplied power to output an alternating current (AC) signal, a trans-module for converting the alternating signal into high-voltage signals having different phases to supply the high-voltage signals to the lamps, an open lamp detecting module for adding low-voltage signals having different phases feedback from the trans-module to detect open states of the lamps, and a controller for controlling an operation of the switching module by a signal detected in the open lamp detecting module.

Abstract: An electrical energy converter (100) arranged to be connected to at least one source of electrical energy (114, 116) and to condition the energy generated by that source to be suitable for feeding to a network (110) to which the converter (100) may be connected, the converter (100) comprising an input conversion stage (104) having at least three input terminals (P1-6) and a controller, the controller (112) being arranged to configure each of the terminals (p1-6) to accept any one of the following input types: 1. a phase of a polyphase supply; 2. one side of a single phase supply; 3. one side of a DC supply; and 4. no-input.

Abstract: A powering arrangement (32, 34) for a device (30, 22) that normally operates on three phase power has the capability of operating based upon single phase power. One disclosed technique includes estimating a direct component based upon a measured voltage across the leads coupled with the single phase power supply. The quadrature component is estimated based upon a numerical derivative of the direct component. The direct component is also provided to a current regulator in a feed forward control manner, which minimizes error.

Abstract: A static converter includes a current converter on the three-phase side and a current converter on the single-phase side, which are electrically conductively linked to one another on the DC voltage side, and which are respectively electrically conductively connected on the AC voltage side to a feeding three-phase network and a single-phase receiving network. According to an embodiment of the invention, one network-commutated current converter is provided as the current converter on the three-phase side, wherein the current converter on the single-phase side has two phase modules which are connected in parallel on the DC voltage side and whose current converter branches each have at least one two-pole subsystem. This results in a static converter which is simpler and costs less than a known static converter.

Abstract: In a power converter apparatus, such as an uninterruptible power supply, a phase reference signal is generated responsive to a DC voltage on a DC bus. A magnitude reference signal may be generated responsive to a phase current of an AC bus and/or the DC voltage on the DC bus. Power is transferred between the AC and DC busses responsive to the phase reference signal and the magnitude reference signal. Generation of the phase reference signal may include generating a DC voltage error signal responsive to the DC voltage on the DC bus, generating a phase offset signal responsive to the DC voltage error signal, and generating the phase reference signal responsive to the phase offset signal. Generation of the magnitude reference signal may include generating a volt-amperes reactive (VAR) error signal responsive to the phase current and generating the magnitude reference signal responsive to the VAR error signal.

Abstract: A converter section converts a three-phase ac input voltage into a dc voltage, and an inverter section converts the dc voltage converted by the converter section into a prescribed three-phase ac output voltage. The converter section converts the three-phase ac input voltage into the dc voltage on the basis of trapezoidal waveform voltage instruction signals from a trapezoidal waveform voltage instruction signal generating part and a carrier signal from a carrier signal generating part. The inverter section converts the dc voltage converted by the converter section 1 into a prescribed three-phase ac output voltage on the basis of an inverter section instruction signal corrected by an instruction signal correcting part. The trapezoidal waveform voltage instruction signal generating part generates sloped regions of the trapezoidal waveform voltage instruction signals by using a prescribed table.

Abstract: Single-phase to three-phase converter comprising a rectifier stage, a DC link and an inverter stage, wherein the rectifier comprises a filter choke, one controllable switch for power factor correction, rectifying diodes arranged in a diode bridge configuration having input terminals and output terminals, the controllable switch being connected to the output terminals of the diode bridge, an upper blocking diode arranged between the positive output terminal of the diode bridge and the positive input of the DC link and a lower blocking diode arranged between the negative output terminal of the diode bridge and the negative input of the DC link, the DC link comprises a capacitor bank connected between the DC link, which capacitor bank has a center point.

Abstract: A three-phase voltage-fed AC/DC converter includes a conversion circuit which converts power from a DC voltage source to three-phase AC power. The converter further includes a UM conversion circuit which carries out dq conversion of the three-phase output voltage, a superior voltage control circuit which outputs a voltage reference vector based on a superior reference vector and an output voltage vector obtained by the UM conversion circuit, an inferior voltage control circuit which outputs a PWM reference based on the voltage reference vector and the output voltage vector, and a frequency control circuit which synchronizes a value generated based on a q-axis component from the UM conversion circuit with a rotation angle of a conversion matrix in the UM conversion circuit.

Abstract: A converter includes a converter circuit 1 having a plurality of bridge-connected semiconductor switching devices for converting AC power into DC power, a smoothing condenser connected in parallel to the DC side of the converter circuit and a current detector provided in a condenser circuit to control a condenser current flowing through the smoothing condenser to be a set value. The condenser current is controlled to be the set value (e.g. zero) to thereby reduce the capacity of the smoothing condenser and make the converter small.

Abstract: A medium or high voltage multi-inverter system is described, in which multiple inverter cells are included in a phase line to increase the voltage level supported by the system, and support higher voltage loads such as AC three-phase motors. In one configuration, five cells are used: two each in two phase lines, and one in a third phase line. In one of the phase lines having two cells, a second cell is series connected in reverse polarity, generates a phase matching the phase of the third line, while the other cell in the phase line generates an output with a different phase. One or more failure switches may be included to allow for short-circuiting of the output poles of one or more of the cells, so that in case of cell failure, the system can continue operation. For example, switches may be employed for the second cells in the two phase lines having two cells, and those cells may be available as spare cells in case of a cell failure.