Abstract: A system of an interconnected inverter includes an inverter that converts DC power from a DC power supply into AC power and provides AC power to an AC power line, an RDC that converts a voltage value obtained by a voltage sensor into electrical angle information that shows a phase angle of an output voltage, the voltage sensor obtaining a voltage value of an output voltage from the inverter to a power grid, and an ECU that controls the inverter to provide an alternating current in synchronization with an alternating current that flows through the AC power line by using timing at which an angle shown in the electrical angle information given from the RDC attains to a prescribed angle. Extra cost for diversion can be reduced.

Abstract: The present invention provides a power control circuit connectable to a load adapted to receive a power supply, the power control circuit adapted to absorb power from the power supply and adapted to deliver power to the power supply to stabilize at least one electrical parameter of the power supply. The present invention also provides an associated method of stabilizing at least one electrical parameter of a power supply connectable to a load, the method including absorbing power from the power supply or delivering power to the power supply. The at least one electrical parameter of the power supply includes parameters such as voltage and frequency.

Abstract: A method produces a digital signal from an analog signal. The method includes: producing a pulse-width-modulated actuation signal by a frequency converter, wherein the pulse-width-modulated actuation signal is produced over a number n of periods of the pulse width modulation such that the signal curve of the pulse-width-modulated actuation signal is identical in the respective periods; applying the actuation signal to a load; producing a bitstream with a predetermined bit repetition duration depending on an analog signal to be measured by a sigma-delta modulator, wherein the analog signal to be measured depends on the actuation signal and on the load, wherein a number m of bits are produced and stored with the predetermined bit repetition duration over a respective period of the pulse-width-modulated actuation signal; and summing corresponding bits of the respective periods in order to form the digital signal.

Abstract: A charge management system including a power distribution bus circuit for distributing energy from a power source to a load, and an intermediate energy storage circuit operably connected to a power distribution bus circuit for aiding in distribution of energy to the load. A charge management system controller may be configured to control the discharge of energy between the intermediate storage circuit and the power distribution bus circuit during one or more modes. Such a charge management system may enable the power distribution bus circuit to receive energy from the intermediate energy storage circuit before the power bus voltage drops in response to load demand, which may enable the power source to respond to perturbations in the power bus voltage and minimize inrush current from the power source. The system also may be used to soft-start high-power equipment, or absorb energy spikes associated with shut-down of such high-power equipment.

Abstract: Unique systems, methods, techniques and apparatuses of power transmission systems are disclosed herein. One exemplary embodiment is an AC power transmission system converted for transmission of high voltage direct current (HVDC) power, the converted system comprising an AC cable system, a first converter system, a second converter system, and a control system. The first converter system is structured to receive and convert AC power to DC power and output the DC power. The second power converter system is structured to receive the DC power, convert the DC power to a second AC power, and output the second AC power. The control system is structured to receive power demand information, determine a reduced DC voltage less than a rated HVDC voltage, control the first converter system such that the DC power is controlled to the reduced voltage, and control the second power converter system to operate in an active power control mode.

Abstract: An inverter power supply system includes an inverter circuit and a feedback circuit, where the inverter circuit is configured to convert a first alternating current voltage into a second alternating current voltage, and convert a first alternating current into a second alternating current; the feedback circuit determines whether a value of the second alternating current voltage exceeds a preset threshold; and when the value of the second alternating current voltage exceeds the preset threshold, the feedback circuit acquires a feedback current, compensates for a reference value of the first alternating current according to the feedback current, generates a control signal according to a reference value, after compensation, of the first alternating current, and outputs the control signal to the inverter circuit to adjust the value of the second alternating current voltage.

Abstract: A hybrid HVDC converter system includes a DC bus, at least one capacitor commutated converter (CCC) and at least one self-commutated converter (SCC) coupled in series through the DC bus. The CCC induces a first voltage on the DC buses, the SCC induces a second voltage on the DC bus, the first voltage and the second voltage are summed to define a total DC voltage. The method includes at least one of regulating the total DC voltage induced on the DC buses including regulating the first DC voltage through the CCC and regulating the second DC voltage through the SCC substantially simultaneously, regulating the total DC voltage induced on the DC bus including regulating the second DC voltage through the SCC, and regulating the total DC voltage induced on the DC bus including regulating the first DC voltage through the CCC.

Abstract: A resonant power converter includes a DC power source, a positive DC conductor, a negative DC conductor, a phase conductor, and a power converting unit between the DC power source and phase conductor. The power converting unit includes a first switch between the positive DC conductor and phase conductor, a first diode in parallel with the first switch, a second switch between the negative DC conductor and phase conductor, and a second diode in parallel with the second switch. The resonant power converter includes a resonant auxiliary switching circuit between the DC power source and phase conductor. The resonant auxiliary switching circuit includes an inductor in series with a control means, and auxiliary diodes in series with the control means. The inductor is a current discriminating inductor adapted to become saturated by currents flowing through the inductor during normal operation such that the inductance of the inductor is reduced.

Abstract: A system and method for electrical power conversion, with the system being intended for use in converting a high voltage DC power output from a turbine generator to an AC power signal that is suitable for connecting to an AC power grid. The system utilizes a mechanical coupling between a synchronous motor driving a synchronous generator in order to provide isolation, as well as allowing for control of the real power output by the system.

Abstract: An electronic apparatus with a DC power source and power-consuming electronic circuits and a method of transferring power between these components include converting the DC voltage of the power source into an AC voltage which is then transferred via a connector to the electronic circuits.

Abstract: An apparatus for controlling a converter has an ignition unit connected to power semiconductors in the converter and provides control signals for actuating the semiconductors. The apparatus has a control unit whose input is connected to measuring sensors providing actual values and whose output side is connected to the ignition unit. The control unit provides a reference variable for the ignition unit based on setpoint values and the actual values and the ignition unit actuates the power semiconductors such that the actual value corresponds to at least one of the setpoint values. A pilot unit has an output connected to the ignition unit and measures for calculating a step change reference variable for the ignition unit on the basis of at least one of the setpoint values. The ignition unit actuates the power semiconductors based on the step change reference variable.

Abstract: A method of controlling an inverter device, a control device, an inverter device and a direct current power transmission system are provided. The direct current power transmission system is provided for connection to an AC voltage bus of an AC power system and includes the control device and the inverter device that converts between DC power and AC power. The control device receives measurements of the voltage (VAC) at the AC voltage bus and controls the inverter device to provide a constant AC voltage on the bus.

Abstract: A Voltage Source Converter having at least one phase leg connected to opposite poles of a direct voltage side of the converter and including a series connection of switching cells has an arrangement configured to apply a pressure to opposite ends of stacks of semiconductor assemblies for pressing the assemblies towards each other so as to obtain electric contact between semiconductor assemblies in the stack while ensuring that the semiconductor assemblies of a first path of each switching cell of the converter go into a permanently closed circuit state in case of a failure of the respective switching cell. A second path of each switching cell has a member configured to keep the second path including an energy storing capacitor non-conducting upon occurrence of the failure.

Abstract: A control system and method for a multi-phase motor substantially reduces or eliminates jitter resulting from. drive mismatch by replacing a conventional trapezoidal drive profile with a drive profile that causes the voltage applied across active phases of the motor to match the back-EMF across those phases. In an ideal motor, the back-EMF is substantially sinusoidal, and although the drive profile applied to each phase is not truly substantially sinusoidal, the drive voltage across the active phases is substantially sinusoidal. In a non-ideal motor, the back-EMF is not truly sinusoidal and the drive profiles applied to each phase are calculated to cause the drive voltage across the active phases to match the back-EMF across those phases.

Abstract: The present invention relates to a circuit arrangement which comprises at least one 3-level pulse width modulation inverter with a snubber circuit. The snubber circuit is formed by at least one coil (L), two capacitors (Cu, Co) and a series connection comprising four diodes (Dh1-Dh4) poled in the same direction, whereof the two outer diodes (Dh1, Dh4) are in each case directly connected to the input terminals (1, 3) for the positive and the negative pole of the input voltage. The electrical connection between the two inner diodes (Dh2, Dh3) is connected on the one hand via the coil (L) to the input terminal (2) for the center tap of the input voltage and on the other hand to the middle bridge branch of the pulse width modulation inverter. In one embodiment, the two capacitors (Cu, Co) are in each case connected with one terminal to the electrical connection between one of the inner diodes (Dh2, Dh3) and one of the outer diodes (Dh1, Dh4) and with the other terminal directly to the output terminal (4).

Abstract: Systems, methods and computer program products for reducing or removing current spikes generated during a current recirculation period associated with phase switching in a spindle motor are described. In some implementations, the duty cycle of the drive signals applied to the windings of the spindle motor can be adjusted to reduce or eliminate the current surge resulting from current recirculation. In some implementations, the duty cycle of the drive signals during spin-up can be reduced based on a current limit, and the reduced duty cycle can then be used to drive the spindle motor taking into account of current surges in the supply current.

Abstract: A control system and method for a multi-phase motor substantially reduces or eliminates jitter resulting from drive mismatch by replacing a conventional trapezoidal drive profile with a drive profile that causes the voltage applied across active phases of the motor to match the back-EMF across those phases. In an ideal motor, the back-EMF is substantially sinusoidal, and although the drive profile applied to each phase is not truly substantially sinusoidal, the drive voltage across the active phases is substantially sinusoidal. In a non-ideal motor, the back-EMF is not truly sinusoidal and the drive profiles applied to each phase are calculated to cause the drive voltage across the active phases to match the back-EMF across those phases.

Abstract: A DC motor is provided. The DC motor prevents rush or overload of current in the DC motor during and/or after power input irregularities to the DC motor. A control circuit of the DC motor is configured to control current provided to the DC motor. When power irregularities in the power input to the DC motor are detected by the control circuit, the control circuit stops generating PWM (Pulse Width Modulated) signals and stops the current provided to the DC motor. After the stoppage of PWM signals, the control circuit can perform a soft-start of the PWM signals when the power irregularities are no longer detected. The soft starting of the PWM signals generates gradual increase in current to the DC motor, thus, preventing sudden rush of current that cause malfunction of the DC motor.

Abstract: The present invention relates to a motor controller of an air conditioner, including a converter for converting a commercial AC power into a DC power, an inverter including a plurality of switching elements, the inverter receiving the DC power, converting the DC power into an AC power through a switching operation and driving a three-phase motor, a gate driver for controlling the switching operation of the switching elements, and a plurality of voltage drop units connected between the converter and the gate driver, the voltage drop units dropping the DC power and supplying driving voltages for an operation of the switching elements. Accordingly, circuit elements within a controller can be protected.

Abstract: In a method for measuring motor speed and position by detecting the back-EMF generated during pole-pair interactions, fluctuations of a three-phase motor power supply that may affect back-EMF detection are reduced. One phase of the power supply is tristated for a certain interval preceding and during back-EMF detection. For a shorter interval during back-EMF detection, the voltage drop across the motor is reduced from the full power supply voltage. This preferably is accomplished either by pulling a first of the other two power supply phases low, while pulling a second of the other two power supply phases up to a regulated voltage below the power supply voltage, or by pulling the second of the other two phases up to the power supply voltage and pulling the first of the other two phases down to a regulated voltage above ground.

Abstract: A power conversion apparatus is formed by connecting unit communication-assisting means in series between an alternating-current terminal incorporated in a conventional current-type power conversion apparatus, and an alternating-current load. The communication-assisting means includes reverse-blocking-type self-commutated devices and a capacitor. By controlling the switching of the reverse-blocking-type self-commutated devices, a voltage is generated at the capacitor and additionally used for a power supply commutation operation or load commutation operation. By virtue of this structure, the power conversion apparatus can easily provide a large capacity (high voltage, large current), and can be improved in power factor. Further, the structure enables the number of required fundamental elements to be reduced, and hence enables the power conversion apparatus to be produced easily at low cost.

Abstract: An auxiliary quasi-resonant dc tank (AQRDCT) power converter with fast current charging, voltage balancing (or charging), and voltage clamping circuits is provided for achieving soft-switched power conversion. The present invention is an improvement of the invention taught in U.S. Pat. No. 6,111,770, herein incorporated by reference. The present invention provides faster current charging to the resonant inductor, thus minimizing delay time of the pulse width modulation (PWM) due to the soft-switching process. The new AQRDCT converter includes three tank capacitors or power supplies to achieve the faster current charging and minimize the soft-switching time delay. The new AQRDCT converter further includes a voltage balancing circuit to charge and discharge the three tank capacitors so that additional isolated power supplies from the utility line are not needed. A voltage clamping circuit is also included for clamping voltage surge due to the reverse recovery of diodes.

Abstract: A microwave oven and a method of controlling the same. The microwave oven is capable of using a plurality of input powers with different frequencies. The microwave oven includes input power sources, an interrupt generation unit and a control unit. The interrupt generation unit generates interrupt signals with different periods according to the frequencies of the input powers. The control unit cumulatively counts pulses generated on the basis of the interrupt signals outputted from the interrupt generation unit, compares the cumulatively counted value with a reference value, and discriminates the frequencies of the input powers depending on the number of instances where the cumulatively counted value is equal to or greater than the reference value.

Abstract: The drive for an a.c. induction motor features a rectifier for converting alternating current into direct current and a current source inverter for converting direct current into alternating current supplied to a motor. A d.c. link choke interconnects the rectifier and the inverter. The inverter includes a first control loop which provides a desired or command d.c. link choke current to a second control loop responsible for the rectifier. For the purposes of the second control loop the actual d.c. link choke current and an input voltage of the inverter are detected. The difference or error between the desired and actual d.c. choke currents are minimized by a compensator. The output of the compensator is added to the detected inverter input voltage, and the sum is fed to a switching pattern generator which controls the switches in the rectifier. In this manner the feedback of the inverter input voltage is decoupled from the compensator responsible for the d.c. link choke current.

Abstract: An auxiliary resonant dc tank (ARDCT) converter is provided for achieving soft-switching in a power converter. An ARDCT circuit is coupled directly across a dc bus to the inverter to generate a resonant dc bus voltage, including upper and lower resonant capacitors connected in series as a resonant leg, first and second dc tank capacitors connected in series as a tank leg, and an auxiliary resonant circuit comprising a series combination of a resonant inductor and a pair of auxiliary switching devices. The ARDCT circuit further includes first clamping means for holding the resonant dc bus voltage to the dc tank voltage of the tank leg, and second clamping means for clamping the resonant dc bus voltage to zero during a resonant period. The ARDCT circuit resonantly brings the dc bus voltage to zero in order to provide a zero-voltage switching opportunity for the inverter, then quickly rebounds the dc bus voltage back to the dc tank voltage after the inverter changes state.

Abstract: A high-density control circuit for an auxiliary resonant commutation pole (ARCP) circuit is internal to the ARCP package and includes a state machine sequencer for providing control and timing signals to achieve high-efficiency, zero-voltage, and fault-tolerant switching converter operation. The phase leg controller receives as inputs a phase enable signal and a pulse width modulation (PWM) signal from a system controller and gate drive feedback signals from main and auxiliary gate drivers. There are four paths the state machine sequencer can take when making a transition from one dc rail to the other, depending on whether the main diode or main switch is conducting and the magnitude and polarity of the inverter pole output current.

Abstract: A power converter comprises two main switches connecting an output either to the positive rail or to the negative rail. Two freewheel diodes for maintaining the current in the load, two snubbers and an auxiliary circuit including an auxiliary inductor in series with two auxiliary switches connected between the output and a mid-point of a capacitive voltage divider supplying a median voltage. Any error of the median voltage relative to its nominal value is evaluated and the main switches are additionally commanded, depending on the direction of the error, for a time period dependent on the amplitude of the error, in order to cause an additional current in the auxiliary circuit to correct the error at least in part.

Abstract: A high power inverter pole for a voltage sourced inverter suitable for providing compensation in electric power transmission and distribution systems, has a positive switching valve and a negative switching valve connected between closely spaced dc-source terminal, respectively, and a common ac terminal to form a current loop with minimum loop area thereby reducing stray loop inductance and limiting the overshoot voltage on serially connected electronic switches which make up the valves. In a preferred embodiment, the valves are mounted on opposite sides of the web of an insulative I-beam. The electronic switches are incorporated in modular switching units connected in series by C-channel connecting conductors having flanges bolted to the I-beam flanges. The modular units include broad, flat conductors bolted through end flanges to the C-channel connecting conductors. The electronic switches and anti-parallel diodes of the modular units are clamped between these broad, flat conductors.

Abstract: An improved zero voltage transition (ZVT) pulse width modulation (PWM) link converter is provided which introduces a space vector modulation scheme and an auxiliary circuit which includes a commutation power supply or special switch arrangement used to discharge resonant inductor currents to zero and to recover commutation energy. In an alternate embodiment, an improved ZVT PWM link converter provides an auxiliary switch for each main switch in the converter to achieve ZVT. The novel ZVT converters provide zero-voltage switching without increasing switching action of the main switches. In this way, the advantages of PWM control is maintained. Conduction loss, turn-off losses, and voltage stress of the main switches are the same as in conventional PWM converters, but the dominant turn-on losses are eliminated, so total power losses are minimized.

Abstract: A novel switching rectifier circuit that combines the conventional three-phase, 6-stepped PWM rectifier/inverter circuit with a simple, low-power switch commutation circuit to provide zero-voltage turn-on for the switches, and soft turn-off for the diodes. The main features of the new circuit include elimination of switching losses on the power switches and reverse recovery problems on the diodes, elimination of the need for any snubbers in the three-phase bridge, possibility of use of slower diodes in the power bridge, constant frequency operation, and no increase in component current and voltage stresses over the conventional PWM rectifier.

Abstract: Method of controlling electric valves of a converter using a universal algorithm for generating pilot signals (11) for multistage and multiphase line- and self-commutated converters (13, 14) is specified, by means of which it is possible to control different types of converters. The control algorithm can be realized as hardware or software. The invention is particularly suitable for multisystem locomotives. It is possible to change over to another feed system of the locomotive by a simple reprograming of a modulator (9) of a pilot signal generator (10). The modulator (9) and a pulse generator (8) receive modulator control signals (7) or pulse generator control signals (6) from a setter (5), together with which they form the pilot signal generator (10).

Abstract: A power converting apparatus controls switching of self turn-off type semiconductor devices so as to perform power conversion. The apparatus comprises a plurality of switch units each having first and second self turn-off type semiconductor devices, first and second diodes, and a capacitor. The cathode of the first self turn-off type semiconductor device is connected to the anode of the first diode, and the cathode of the second diode is connected to the anode of the second self turn-off type semiconductor device. The capacitor is connected between a common junction between the cathode of the first self turn-off type semiconductor device and the anode of the first diode and a common junction between the cathode of the second diode and the anode of the second self turn-off type semiconductor device.

Abstract: An improved commutation arrangement for an AC to AC or AC to DC energy converter circuit is disclosed. The improved arrangement uses turn-off capable commutation switches to enable modification of the operating waveforms in the cycloconverter. The modified waveforms include an operating concept wherein in lieu of always switching to the next lagging phase (as is done with conventional cycloconverters), an intervening switch is made to the leading phase when the output voltage is less than one-half of the maximum value. The disclosure includes mathematical consideration of source machine power factor, output waveform ripple content, interphase transformer characteristics, engine starting usage, and other refinements of the commutation arrangement.

Abstract: In circuits with self-commutation such as, for example in inverters (4) for feeding an asynchronous machine (7), a short-time turn-off current impulse is taken from a turn-off capacitor (C1) of a turn-off or common turn-off circuit (3) for interrupting the thyristor current of the inverter. The turn-off circuit (3) connected to the direct-current side (8, 9) of the inverter (4) exhibits a first series circuit of the turn-off capacitor (C1) and a first electrical valve (T2, D2). In a branch in parallel with the turn-off capacitor (C1), a ring-around reactor (L1) with an inductance of 0.1 mH is connected in series with a second thyristor (T1). A further third thyristor (T3) is connected in antiparallel with the second thyristor (T1). A ring-around process initiated by the firing of the second thyristor (T1) is interrupted after a half period. After a freely selectable time, the third thyristor (T3) can be fired and the full resonance cycle can be concluded.

Abstract: An auxiliary quasi-resonant dc link (AQRDCL) converter is employed to achieve soft-switching in an inverter coupled to a dc supply via a resonant dc link circuit. The resonant dc link circuit generates a quasi-resonant voltage to the inverter via a resonant bus. The dc link circuit includes upper and lower capacitors coupled to series between the positive and negative rails of the dc supply, respectively, with the voltage across the lower capacitor being controlled to be greater than the voltage across the upper capacitor. In this way, the need for a switch shorting the resonant bus to ground during a resonant cycle is avoided. An auxiliary switching device assists resonant operation of the resonant bus to zero voltage in order to provide a zero-voltage switching opportunity for the inverter switching devices as the inverter changes state.

Abstract: The invention is a circuit (60) for controlling the operation of a variable reluctance machine having a plurality of phase windings. Pairs of phase windings (64, 66 or 65, 67) are controlled by a switching circuit having only three power switches which are controlled by a switch controller. Pairs of phase windings may be switched by one or more sets of switches each having the three power switches in several different modes of operation. The invention may be used to control multiple phase machines with an odd number of phases.

Abstract: A converter of the electric energy fed by a unidirectional voltage source, comprising a voltage inverter circuit arranged to deliver an alternating voltage, possibly polyphase, to an inductive load such as an electric motor, wherein between the energy source and the voltage inverter circuit there is inserted a set of components arranged for controlling in an active manner the supply voltage of the inverter circuit, limiting the maximum value of the voltage applied thereto and assisting the commutation by transitorily bringing to zero (or to a negative value) the supply voltage applied to the inverter circuit during the periods of time in which any commutation should be carried out therein. This set of components includes a capacitor connected, through a diode, in parallel to the unidirectional voltage source, a first controlled switch inserted in parallel to the diode, and a second controlled switch inserted in parallel to the inverter circuit input.

Abstract: A method for controlling a power converter and an associated auxiliary commutation circuit ensures soft-switching of all switching devices employed therein. Such a power converter includes an inverter with at least two main switching devices per phase. Across each main switching device are connected an antiparallel diode and a relatively large snubber capacitor. The auxiliary resonant commutation circuit comprises two antiparallel-coupled auxiliary switching devices coupled in series with a resonant circuit including an inductor and the snubber capacitors. The gating and conduction times of the main and auxiliary switching devices are controlled so as to add boosting energy to the resonant operation, thus ensuring that the inverter output voltage at least reaches the positive and negative inverter rail voltages during each resonant commutation cycle. As a result, the control achieves commutation of the converter pole with substantially no switching losses.

Abstract: A low-loss and low-reactive power switching relief circuit has an inverter output section coupled at its upper and lower ends to the positive or negative potential of a DC voltage source, respectively. The coupling is via saturable stepping choke coils. A wiring network serves as a switching relief for the semiconductor switches of each inverter phase. A circuit having a switching-off relief capacitor, two storage capacitors and two switching-off relief diodes causes uniform switching-off relief. A circuit having two current rate of rise limiting choke coils and four feedback diodes causes uniform switching-on relief of the upper and lower semiconductor switches, respectively. By means of the stepping choke coils, the output section and the wiring network are temporarily decoupled from the DC voltage source during the switching-on process of one of the semiconductor switches. This occurs in such a manner that the interim-stored trapped energy is fed into the load nearly without loss and any reactive power.

Abstract: A novel inverter circuit having symmetrical gate turnoff thyristors (GTO) includes reactive circuit elements for recovering stored energy. The circuit is characterized by a center tapped transformer configured without tightly coupled anti-parallel diodes, thereby allowing for the presentation of reverse voltages to each GTO.

Abstract: A detecting apparatus for abnormality in an inverter circuit comprising an inverter circuit for converting electric power in a DC circuit into that in an AC circuit and vice versa based on a command signal for commutation, a detecting circuit for commutation in a main circuit, the detecting circuit being composed of a current detecting circuit provided between a voltage dividing point of the DC circuit and the inverter circuit and provided with its one end connected to the voltage dividing point and a differentiating circuit connected between the other end of the current detecting circuit and the AC terminal of the inverter circuit, and, a logic circuit for judgement of abnormality in commutation, the logic circuit comparing a detected signal of the detecting circuit for commutation in the main circuit with a command signal for commutation for commanding its commutation for the inverter circuit, and, at the same time, detecting inconsistency in logics of the detecting signal and command signal for commutation

Abstract: A pulse width modulated inductive load controller including a load switching circuit having a plurality of switches which are operative in pairs; each pair including first and second switch devices for controlling power to a load. Commutation logic enables various sequential combination of pairs of switch devices and a clock defines the operation period of each sequential combination of switch device pairs. Pulse width modulation circuitry controls the closed time interval of the switch devices during the operation period of each combination of switch device pairs. Transition control circuitry maintains closed at least one of the switch devices in each sequential combination of switch device pairs after the other switch device is opened, thereby assuring that any regenerated current from the previously energized load coils is provided a path to recirculate through the load.

Abstract: A method and apparatus to avoid commutation failure in a regenerative converter of a supply reversible converter of a voltage-source converter, in case of dynamic voltage depression. A firing control of the reversible converter is a function of the value of a link current setpoint of the voltage-source converter. The link current setpoint is determined from a measured link voltage actual value and from a determined link voltage setpoint. A measured link current actual value is monitored for overcurrent. Control signals are supplied to the reversible converter even when there is an overcurrent status message, when the reversible converter is switched over. The reversible converter of the voltage-source converter is thereby protected from commutation failure.

Abstract: In a load commutated inverter induction motor drive a parallel capacitor bank is used in part to force-commutate the thyristors of the inverter as triggered by auxiliary thyristors and turned off by the other part of the capacitor bank.

Abstract: In a load commutated induction motor drive stability is achieved in a runaway situation by generating in response to the motor speed reference signal a signal representative of the desired power factor angle and in using such signal to delay by that much the gating pulses controlling the current-sourced inverter.

Abstract: A variable speed motor control system includes a power control circuit and a forced commutation control circuit for controlling the torque and rotational speed respectively of an induction motor. The power control circuit and the forced commutation control circuit are independently controlled by signals from a speed control circuit. An overcurrent sensor monitors the motor current and, if excessive current is detected, a speed and power monitor limits the response of the power control circuit and forced commutation control circuit to the speed command. The forced commutation control circuit and power drive circuit contain silicon-controlled rectifiers both for controlling the amount of power fed to the induction motor as well as for controlling the switching of power between combinations of motor windings.

Abstract: An improvement in a commutation control method or a control circuit for a converter comprising a plurality of converter units connected in cascade, which is provided with a circuit which maintains a phase control angle of each converter unit in an about constant angular difference within a range of a specified converter output, thereby enabling precision output control, reduction of the ripple in a delivered current to a load, and an improvement in power factor of an input fundamental wave in comparison with the symmetric control.

Abstract: A versatile current source inverter power supply for an ozonator in which a gating control circuit controls the gating of a thyristor bridge inverter power supply in a manner in which the output current to the ozonator is controlled and regulated. The current source inverter power supply circuit includes a DC/AC thyristor bridge inverter circuit coupled at its input terminals to a direct current power source and at its output terminals to an electrical network which includes the capacitative ozonator load. The thyristor bridge inverter includes a first pair of thyristors and diodes coupled to conduct current in a first direction through the electrical network, and a second pair of thyristors and diodes coupled to conduct current in a second, opposite direction through the electrical network. The electrical network includes a step up high voltage transformer, with its primary winding coupled to the thyristor bridge inverter and its secondary winding coupled to the ozonator load.

Abstract: A simultaneous recovery commutation current source inverter is provided by connecting three AC output terminals of a main inverter and an auxiliary inverter in parallel with each other and to three terminals of an induction motor, providing a high AC impedance DC current source through inductors connected in series to a variable DC electric source so that DC electric power is supplied to both sides of a main DC bus of the main inverter, providing a low AC impedance DC voltage source by supplying DC electric power to both sides of an auxiliary DC bus of the auxiliary inverter through a rectifying circuit from the respective connecting points of the main inverter, auxiliary inverter and the three motor terminals. Snubber circuits may be added to the respective semiconductor elements for safe switching operation.

Abstract: A system is disclosed for recovering and storing the energy generated by an electrical motor during deceleration so as to be available for use when the motor is subsequently accelerated. The system utilizes a capacitor for storing the energy produced by voltage regeneration of the motor when decelerating. A two-quadrant regulator, connected between a three-phase rectifier and a four-quadrant SCR regulator, controls the charging and discharging of the capacitor so that the energy stored therein is proportional to the energy required to accelerate the motor and load to the maximum rotational velocity required.