Abstract: A motor controller comprises a switch circuit and a control unit. The switch circuit is coupled to a motor for driving the motor. The control unit is configured to generate a control signal to control the switch circuit. The motor controller is configured to generate a current signal and a voltage signal. When a current phase of the current signal is at a predetermined crossing phase, the motor controller calculates a difference value between the current phase of the current signal and a voltage phase of the voltage signal, where the motor controller is configured to control the difference value. The motor controller may stabilize the motor and avoid noise by modulating the difference value. The motor controller may modulate the difference value, such that the difference value is equal to a predetermined phase difference.

Abstract: An electronic device may include: a power management integrated circuit (PMIC); and a micro controller unit (MCU) electrically connected to the PMIC. The MCU may be configured to: generate, based on a first driving power signal output from the PMIC to drive the MCU, a digital signal for determining an error in a reference signal of an analog-to-digital converter (ADC) included in the MCU; identify an error rate of the digital signal; and determine a mode for controlling a motor driven power steering system, based on the error rate of the digital signal.

Abstract: System and method for controlling one or more light emitting diodes. For example, the system includes: a current regulator including a first regulator terminal and a second regulator terminal, the first regulator terminal being configured to receive a diode current flowing through the one or more light emitting diodes, the current regulator being configured to generate a sensing signal representing the diode current, the second regulator terminal being configured to output the sensing signal; a bleeder controller including a first controller terminal and a second controller terminal, the first controller terminal being configured to receive the sensing signal from the second regulator terminal, the bleeder controller being configured to generate a first bleeder control signal based at least in part on the sensing signal, the second controller terminal being configured to output the first bleeder control signal.

Abstract: A method for diagnosing the cause of tripping of an electrical protection device includes, after detection by the auxiliary device of a loss of electrical power, determining a type of electrical fault on the basis of recorded values, the determining operation including: comparing, with a first threshold value, the largest value of the maximum intensity of the current from the recorded values for a plurality of measurement intervals preceding the loss of power, a short circuit being diagnosed if the largest value of the maximum intensity is greater than a first threshold value; comparing, with a second threshold value, the largest RMS value of the current from the recorded values, an overload being diagnosed if the largest RMS value is greater than a second threshold value.

Abstract: An amplifier includes: a signal polarity inversion circuit which modulates an input signal and outputs a modulation signal; an amplifier circuit which is constituted from an operational transconductance amplifier (OTA) to amplify the modulation signal and output a current; and a sample-hold circuit having a sampling capacitor which is charged and discharged by selective sampling of the output current of the amplifier circuit and a holding capacitor to which the voltage of the sampling capacitor is transferred.

Abstract: An electrical connector assembly for mating with a mating connector assembly. The connector assembly includes a housing having a first surface and a second surface. At least one magnet is provided the housing. A mating area extends from the first surface. The mating area has a sloped surface, which is sloped relative to a plane of the first surface of the housing.

Abstract: A modular multi-level converter including modules each having switching elements and at least one electrical energy storage element, wherein a first number of modules are interconnected to form a closed ring, and at least two taps are arranged between respective adjacent individual modules of the closed ring. Wherein at at least two taps respectively a second number of modules are provided as a phase module branching off from the closed ring and forming a star string comprising at least two modules, the phase module connected to the respective tap on one end and forming a phase terminal at an other end. Wherein the switching elements enable interconnection of energy storage elements of adjacent modules, as a result of which between two adjacent phase terminals a voltage difference is provideable, which is regulatable by a control unit in accordance with a polyphase rotating field profile.

Abstract: A controllable electric current switchgear includes a bistable relay including separable electrical contacts and an excitation coil for switching the contacts between open and closed states when the coil receives an amount of energy that is higher than a predefined excitation energy threshold with an electrical power that is higher than a predefined power threshold; and a control circuit including a power stage and a logic stage for triggering the switching of the relay. The power stage includes a power converter, a first set of capacitors connected at the input of the converter and a second set of capacitors connected at the output of the converter, the nominal power of the converter being strictly lower than the power threshold, the sets of capacitors being capable of storing an amount of energy that is higher than or equal to 50% of the excitation energy threshold.

Abstract: A motor driving circuit includes a Hall sensor, an offset detecting circuit, a driving circuit and a back EMF zero point detector. The Hall sensor generates a Hall signal group, the offset detecting circuit detects the first phase changing point of the Hall signal group, and the driving circuit generates the initial phase changing signal in the pre-operation mode according to the Hall signal group. In the correction mode, the driving circuit stops outputting the initial phase changing signal, the back EMF zero detector detects the back EMF zero point, and outputs the back EMF zero point signal. The offset detecting circuit detects a phase difference between the first phase changing point and back EMF zero point, and determines a difference value between the phase difference and a predetermined phase difference. Then, the phase of the Hall signal group is adjusted according to the difference value.

Abstract: A motor driving circuit includes a Hall sensor, a driving circuit, a phase adjuster, and a phase current zero point detector. The Hall sensor detects the rotor position of the motor and generates the Hall signal group. The driving circuit generates the initial phase changing signal according to the Hall signal group. The phase current zero point detector receives and detects the phase current zero point of the phase current signal group, and generates and outputs the phase current zero point signal. The phase adjuster determines a phase difference between the phase current zero point and the intermediate point between the first phase changing point and the second phase changing point, and adjusts the initial phase changing signal according to the phase difference to generate and output the adjusted phase changing signal to drive the motor.

Abstract: A three-phase UPS control method and apparatus, and a three-phase uninterruptible power supply resolve a problem that after a zero wire is lost, when a current control method is applied to a three-phase UPS using a three-level topology, a 0-axis direct-current modulated wave results in that positive and negative buses are unbalanced. The method includes: determining that a zero wire of a three-phase uninterruptible power supply is lost; using an alternating current whose frequency is a harmonic frequency of mains as a 0-axis reference current; and generating a 0-axis modulated wave according to a difference between the 0-axis reference current and a 0-axis sampling current, to control a rectifier in the three-phase uninterruptible power supply to convert a received alternating current to a direct current.

Abstract: In some examples, a device includes control circuitry configured to receive a first input signal, receive a second input signal, and cause gate driver circuitry to deliver a driver signal to a switch to cause the switch to deliver electrical power to an electrical load. In some examples, the control circuitry is further configured to determine whether the first input signal has an active value and determine whether the second input signal has an active value. In some examples, the control circuitry is also configured to cause the gate driver circuitry to change the driver signal across a switching cycle of the switch to increase or decrease the electrical power delivered by the switch to the electrical load in response to determining that the first input signal has the active value or in response to determining that the second input signal has the active value.

Abstract: The invention provides a full-automatic network transformer winding machine, comprising a T1 ring winding device and a T2 ring winding device connected with said T1 ring winding device, wherein said T1 ring winding device includes an enameled wire pre-cutting mechanism, a stranding mechanism before T1 ring winding, a T1 ring winding mechanism and a tail wire-cutting mechanism which are connected with one another sequentially, and said T2 ring winding device includes a separating mechanism, a stranding mechanism before T2 ring winding and a T2 ring winding mechanism which are connected with one another sequentially. The full-automatic network transformer winding machine of the invention can completely replace manual winding to manufacture the network transformer, has high production efficiency and high product acceptability, and meanwhile provides great convenience to automatically realize shell mounting and end wrapping in subsequent processes.

Abstract: An uninterruptible power supply system includes a plurality of uninterruptible power supply devices, and each uninterruptible power supply device includes a conversion circuit, an inversion circuit, a DC positive bus, a DC negative bus, and a capacitor. The uninterruptible power supply system includes a first fuse connected between DC positive buses of two uninterruptible power supply devices, and a second fuse connected between DC negative buses of the two uninterruptible power supply devices. DC voltages between the plurality of DC positive buses and between the plurality of DC negative buses can be made uniform and a cross current can be suppressed. Even when one uninterruptible power supply device fails and an overcurrent flows between the two DC positive buses and between the two DC negative buses, the failure range can be narrowly limited by the first and second fuses.

Abstract: An electronic apparatus includes: a power supply circuit that supplies power supply voltage to a load; an overcurrent detection circuit that performs output of detection information indicating the direction of current at a power supply path for the load in the power supply circuit when overcurrent occurs in the power supply path; and a determination circuit that performs output of notification information indicating whether or not a location at which a failure occurs exists within the power supply circuit or outside the power supply circuit, based on the detection information.

Abstract: An electronic apparatus includes: a power supply circuit that supplies power supply voltage to a load; an overcurrent detection circuit that performs output of detection information indicating the direction of current at a power supply path for the load in the power supply circuit when overcurrent occurs in the power supply path; and a determination circuit that performs output of notification information indicating whether or not a location at which a failure occurs exists within the power supply circuit or outside the power supply circuit, based on the detection information.

Abstract: In accordance with an embodiment, a converter includes a power factor controller that varies the switching frequency of a switching transistor in accordance with a signal representative of power at the input of the converter.

Abstract: A matrix converter includes: a power converter configured to couple an AC power supply and a load together; and a controller configured to selectively execute: a first control mode in which the controller is configured to perform power conversion between the AC power supply and the load; and a second control mode in which the controller is configured to directly combine the AC power supply with the load. The controller is configured to: increase the output voltage and cause a phase of the output voltage follow up a voltage phase of the AC power supply in a case where a difference between a frequency of an output voltage from the power converter to the load and a frequency of the AC power supply becomes within a predetermined range.

Abstract: A cycloconverter has six converter branches connected in series, and said converter branches have energy stores. A method for controlling the cycloconverter connecting a first three-line network to a second three-line network includes controlling the converter operation by controlling energy transfer from the first three-line network to the second three-line network or vice versa according to energy demand criteria, energy supply criteria, and/or reactive power criteria, and by controlling the amount of electrical energy stored in each converter or by controlling an electrical variable that characterizes the amount of electrical energy to a specified target range. The invention further relates to an electronic control device for such a cycloconverter, and to a computer program for carrying out the method.

Abstract: The invention relates to a device (50) for limiting an electrical current in an electrical conductor of an electrical installation. The device (50) comprises a receiving unit adapted to receive a measurement of the electrical current in the electrical conductor, and further comprising a limiting unit adapted to limit said electrical current when the measured electrical current reaches a threshold. The device (50) is distinguished by comprising an obtaining unit adapted to obtain electrical energy from a second electrical conductor, wherein the limiting unit is adapted to inject said obtained electrical energy as an electrical current into the first electrical conductor, whereby the injected electrical current constitutes a replacement for at least a part of the first electrical current, which first electrical current is thereby limited. The invention also relates to an electrical system and a method for limiting an electrical current in an electrical conductor of an electrical installation.

Abstract: A phase control apparatus includes a first transistor whose source or emitter is connected to one end of an AC power supply and whose drain or collector is connected to one end of a load, a second transistor whose source or emitter is connected to the other end of the AC supply and whose drain or collector is connected to the other end of the load, a diode bridge that rectifies an AC voltage of the AC supply, and a parallel circuit of a zener diode and a capacitor. The parallel circuit generates a high potential relative to a bridge negative output terminal potential, or generates a low potential relative to a bridge positive output terminal potential. First and second transistor control terminal potentials are switched between the high and the bridge negative output terminal potentials, or between the low and the bridge positive output terminal potentials.

Abstract: A motor energy recycling device is connected to a motor, a voltage regulating power capacitor, and a switch unit, for storing energy released by the motor. The motor energy recycling device include a switching device having first to third ends for being switched to connect the third end with the first end or second end; a first diode unit; a first capacitor connected to the motor and the first diode unit for using energy released by the motor to charge the first capacitor; a first inductor; a second capacitor; a second diode unit; and a second inductor connected between the second end and the second diode and between the voltage regulating power capacitor and the second capacitor for charging the voltage regulating power capacitor via the second inductor to accomplish an energy recycling.

Abstract: A controller for a switched mode power supply converting an input voltage to a regulated output voltage according to one embodiment includes a control network and a detection network. The control network develops a pulse width control signal for regulating a level of the output voltage. The detection network detects a phase lag of the output voltage and adjusts operation of the control network based on the phase lag. The phase lag may be determined from any parameter incorporating phase shift, such as the output voltage or the compensation voltage. Various alternative schemes are disclosed for adjusting the control loop, including, but not limited to, adding slope compensation, adjusting window resistance or window current, adding adjustment current to adjust ripple voltage, adjusting ripple transconductance, and adjusting ripple capacitance. Digital and analog compensation adjustment schemes are disclosed.

Abstract: The present invention discloses an active bleeder circuit capable of triggering a tri-electrode AC switch (TRIAC) circuit in all phase. The active bleeder circuit receives a rectified signal having an OFF phase and an ON phase. The active bleeder includes: a detection circuit for generating a detection signal according to the rectified signal and accumulating the detection signal in the OFF phase of the rectified signal; and a current sinker circuit coupled to the detection circuit, for generates a latching current to trigger the TRIAC circuit by operating a switch when the detection signal exceeds a predetermined level. The present invention also discloses a light emitting device power supply circuit and a TRIAC control method using the active bleeder circuit.

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 alternating current motor control system constituted of: a control unit; a cycloconverter functionality; a phase control functionality; and a semiconductor switching unit comprising a plurality of electronically controlled semiconductor switches each associated with a particular winding of a target alternating current motor and each independently responsive to the control unit. In one embodiment the semiconductor switching unit is arranged to connect the windings of the target alternating current motor to a three phase power input in one of a star and a delta configuration responsive to the control unit.

Abstract: Methods and apparatus are provided for operation of a voltage source inverter. A method of operating a voltage source inverter having an output with multiple voltage phases having a DC voltage level, the method comprising sensing a low output frequency condition; determining a DC voltage offset responsive to the low output frequency condition; and applying the DC voltage offset when operating the voltage source inverter resulting in a change to the DC voltage level of the multiple voltage phases.

Abstract: There is provided an inverter device capable of simplifying the circuit structure, lowering the cast, and downsizing of the device. The inverter device detects a switching change of an inverter by a pulse and is equipped with a pulse signal detector capable of detecting a motor residual voltage or a phase and a detector for detecting a residual voltage or a phase. The inverter device includes a voltage detector, a circuit for detecting a pulse signal based on a comparison between a phase voltage detection value per one phase output from the voltage detector and a first reference voltage value, a circuit for detecting a line residual voltage based on phase voltage detection values of two phases output from the voltage detector, and a circuit for detecting a line phase based on a comparison between the line residual voltage and a second reference voltage value.

Abstract: A voltage regulator has an error amplifier circuit, and a phase compensation circuit having a capacitor connected in parallel to first and second series-connected resistors. A control transistor has its source-drain path connected between input and output terminals of the phase compensation circuit and its gate connected to a junction point between the first and second resistors. In a transient stage in which the output voltage of the error amplifier circuit changes, the resistance of the phase compensation circuit decreases thereby improving the transient response characteristics of the voltage regulator.

Abstract: A rotating electrical machine control device includes an inverter; a resolver; a unit; a three-phase/two-phase modulation switching unit; and a motor control unit that switches to a two-phase modulation in a specific region where an electric noise given to the resolver by a rotating electrical machine is large, even in a region where the modulation ratio is smaller than the three-phase/two-phase modulation switching boundary.

Abstract: A power control method using AC power, the method being capable of performing: low power control that passes only two portions of positive direction waves of each one-cycle sine wave of the AC power and only two portions of negative direction waves of each one-cycle sine wave of the AC power, which have voltage levels lower than a set reference voltage level, through a system; and high power control that does not pass only two portions of positive direction waves of each one-cycle sine wave of the AC power and only two portions of negative direction waves of each one-cycle sine wave of the AC power, which have voltage levels lower than a set reference voltage level, through the system.

Abstract: A power supply includes a first switch to establish a first path to charge an output of the power supply by a voltage source, a second switch to establish a second path to discharge the output, and a third switch connected between the output and a capacitor. When to discharge the output, the third switch is turned on before the second switch turns on, to transfer a portion of energy on the output to the capacitor. When to charge the output, the third switch is turned on before the first switch turns on, to transfer a portion of the energy on the capacitor to the output.

Abstract: A control apparatus for an AC-AC direct converter. The control apparatus includes a calculator providing a phase command ?* of an output voltage of the converter, a calculator providing a q-axis current iq by using output currents iu and iw and the phase command ?*, a detector detecting a pulsation component contained in the q-axis current iq, a calculator providing a phase correction magnitude ?cmp so as to decrease the pulsation component, and an adder/subtractor correcting the phase command ?* by using the correction magnitude ?cmp. This apparatus can decrease the output voltage distortion and low frequency torque pulsation and can suppress the increase of an output current without weakening a magnetic flux, even when the converter is operated in an overmodulation region.

Abstract: Provided is a voltage regulator capable of performing appropriate phase compensation. Even when a difference between an input voltage and an output voltage is small, an appropriate phase compensation voltage based on an output voltage (Vout) is generated in a resistor circuit (19), and the appropriate phase compensation voltage is applied to a phase compensation capacitor (20). Accordingly, the voltage regulator is capable of performing appropriate phase compensation.

Abstract: According to one exemplary embodiment, an efficient and high speed E-mode III-N/Schottky switch includes a silicon transistor coupled with a D-mode III-nitride device, where the silicon transistor causes the D-mode III-nitride device to operate in an enhancement mode. The E-mode III-N/Schottky switch further includes a Schottky diode coupled across the silicon transistor so as to improve efficiency, recovery time, and speed of the E-mode III-N/Schottky switch. An anode of the Schottky diode can be coupled to a source of the silicon transistor and a cathode of the Schottky diode can be coupled to a drain of the silicon transistor. The Schottky diode can be integrated with the silicon transistor. In one embodiment the III-nitride device is a GaN device.

Abstract: A power generating apparatus including an AC generator that supplies electric power to a load including a voltage accumulating means, an inverter that applies AC control voltage to armature winding of the generator from the voltage accumulating means, and a controller that controls a phase of control voltage applied to the armature winding by the inverter to keep load voltage at a target value, wherein the phase of the control voltage is controlled so as to advance when the load voltage is higher than the target value, hold the present phase when the load voltage is equal to the target value, advance when the load voltage is lower than the target value and a phase of phase voltage of the generator is delayed behind a phase of a phase current of the same phase, and delay when the load voltage is lower than the target value and the phase of the phase voltage of the generator is advanced ahead of a phase of a phase current of the same phase.

Abstract: A method for generating a reading signal of a sense element in at least a phase of a multiphase controller controlled by means of PWM control signals having a preset period and a duty cycle varying according to the load current and voltage of said controller, the reading signal being a digital signal having a first logic value during a reading period and a second logic value at the end of the reading period and showing a periodical trend which has a half cycle. The method provides that the value of said half cycle is so set that the reading period ends in a different instant from the switching instants of external power transistors comprised in the driving circuits of the controller phases not being read.

Abstract: A method of operating a lamp that has a power controller connected between a terminal and a light emitting element that converts the line voltage to an RMS load voltage. An input to an analog control block is provided in the controller that is independent of a change in magnitude of the line voltage. A trigger signal from the analog control block is provided at a first frequency by charging and discharging a capacitor in the analog control block that receives the input. An initial condition of the analog control block is resetted periodically. A sync signal synchronizes the trigger signal with a waveform of the line voltage. A load voltage is clipped based on the synchronized trigger signal to define the RMS load voltage.

Abstract: A phase-control power controller that converts a line voltage to an RMS load voltage includes a phase-control circuit connected to the line and load terminals and having an RC network that clips the load voltage. A load sensing circuit is connected across the load terminals that senses the load voltage and provides a DC signal that is related to an RMS load voltage. A comparison circuit is connected to the phase-control circuit and the load sensing circuit and compares the DC signal to a reference and adjusts a resistance of the RC network in response to the comparison of the DC signal to the reference to control the RMS load voltage.

Abstract: A method for coupling an inverter to an alternating voltage source, the inverter comprising a current controller, which controls phase currents and implements reference current. The method comprises steps of giving zero current as the reference current for the current controller, determining phase voltages of the inverter, determining frequency of the alternating voltage source from the determined phase voltages, and synchronizing and coupling the inverter to the determined frequency of the alternating voltage source.

Abstract: A frequency converter includes a transistor pair having a first transistor and a second transistor respectively having collector terminals commonly connected to each other and emitter terminals commonly connected to each other, the commonly-connected collector terminals of the transistor pair being connected to a power supply terminal by way of a first resistor, a third transistor having a collector terminal connected to the power supply terminal by way of a second resistor and an emitter terminal connected to the commonly-connected emitter terminals of the transistor pair, a third resistor having an end connected to the commonly-connected emitter terminals of the transistor pair, and another end grounded by way of a constant current source, and an output terminal connected to the commonly-connected collector terminals of the transistor pair.

Abstract: A phase-shift modulation resonant inverter is turned on and off by built-in switches Q1 and Q2. An inductor L and a load capacitor C are used to produce vibration output from the inverter. A current sampling circuit is employed to take samples of resonant current. A controller is used to adjust the shift angle between the phase of switches Q1 and Q2 and that of resonance current. This invention features simple structure, flexible control and a wide range of voltage changes, with an efficiency up to 98%.

Abstract: A phase-shift modulation resonant inverter is turned on and off by built-in switches Q1 and Q2. An inductor L and a load capacitor C are used to produce vibration output from the inverter. A current sampling circuit is employed to take samples of resonant current. A controller is used to adjust the shift angle between the phase of switches Q1 and Q2 and that of resonance current. This invention features simple structure, flexible control and a wide range of voltage changes, with an efficiency up to 98%.

Abstract: A power supply for an LCD and a voltage sequence control method in which the sequence for voltages applied to a gate driver IC for outputting a driving voltage of an LCD panel is controlled by arranging a switching element between a DC-to-DC converter and the gate driver IC so as to switch a turn-on voltage to a turn-off voltage to be applied to the gate driver IC, and a latch up is prevented by arranging diodes in reverse and forward directions to the lines for applying the turn-on and turn-off voltages respectively so that the applied voltage is not deviated from the latch up preventing scope. Voltages are applied or removed from the gate driver IC in accordance with a predetermined sequence, and an abnormal voltage is prevented from being applied in an early stage of driving, to thereby stabilize the LCD panel operation.

Abstract: The method according to the invention is for compensation currents to be produced which have arbitrary phases and/or arbitrary amplitudes. To this end, a compensation unit (5) is proposed which is connected to the polyphase system via a transformer unit (4). The compensation unit (5) in this case comprises at least a switching unit (6) and an energy storage unit (7), which is connected to the transformer unit (4) via the switching unit (6).

Abstract: A static series voltage regulator (SSVR) for an electric power distribution system protects a load on a feeder branch from voltage dips by boosting voltage under certain conditions. The SSVR contains a 3-phase voltage source inverter and a source bridge, fed from a source, supplying the dc side of the inverter. A series transformer is connected between the power source and a load coupling the inverter output to appear between the power source and the load. A surge filter connected in parallel with the series transformer protects the load from fast front voltage pulses produced by the inverter, and isolation and bypass switches isolate the inverter and series transformer from the power source and load. The inverter is controlled so that during normal operation it acts as a short on the series transformer, and, during a fault that causes a dip in the source voltage, it injects voltage in series with the source voltage to provide a boost action to maintain load voltage at a desired magnitude and balance.

Abstract: A power factor correction controller circuit 100 for controlling the duration of each on time phase and off time phase of a switched inductor power factor correction circuit 20, 30, 40, 50, 100 which is adapted for use with a rectifying arrangement 9, 10, 60, 70 producing a substantially regulated output voltage, Vo. The controller circuit 100 comprises an input terminal 114 for receiving a signal representative of Vo; an output terminal 131 for outputting a signal representative of the duration of each on time phase and off time phase; and on time determination means 110, 111, 112, 113, 114, 115, 116, 117; wherein the on time determination means acts to vary the maximum duration of each on time phase in an inverse dependence on Vo.

Abstract: An active circuit for delivering three phase AC input power received from a three phase rectifier to a boost converter and a method of operating the same. In one embodiment, the active circuit includes a phase selection switching circuit, coupled to the rectifier, that selects an inner phase of the three phase AC input power. The active circuit also includes a switching network, coupled to the phase selection switching circuit and the rectifier, that controls a current waveshape of the inner phase and a current waveshape of at least one other phase, thereby to reduce harmonics associated with three phase AC input current.

Abstract: A control arrangement for a multilevel convertor employs an AC reference signal which is locked to the AC system frequency and is compared with a number of DC threshold levels. Intersections of the reference signal and threshold levels triggers the firing and turning-off of GTOs within the convertor to produce the desired multilevel voltage output. Normal changes in system voltage, for example, are compensated by variation of the phase relationship of the reference signal with respect to the system voltage, and/or of the voltage values of the threshold levels. Sudden and drastic changes, especially reductions, in system voltage level are sensed and used to alter the amplitude of the reference signal so as to reduce the difference between the convertor multilevel voltage and the system voltage, thereby reducing the stress on the GTOs during faults.

Abstract: A method and apparatus for operation of an electrical power conversion system having first and second partial systems connected in parallel. Each partial system includes an inductor and an electronic switch for controlling electrical power transferred through the partial systems. A control circuit controls operation of the electronic switches. The control circuit includes devices for generating a first control signal error and a second control signal error as a function of a reference and current flowing in the inductors. Hysteresis devices receive the first and second control signal errors and provide first and second outputs, respectively, upon intersection of the first and second control signal errors with selected threshold values. Delay devices coupled to the electronic switches receive and delay transmission of the first and second outputs to the electronic switches.