Abstract: The concepts described herein provide a method, apparatus, and system for controlling an inverter by modifying duty cycles of the PWM control signals in a manner that achieves a minimum duration between consecutive switching events in the inverter, which serves to reduce common mode current in the bearing(s) of an attached rotary electric machine. To minimize the effect of additional current and voltage ripple into the system, the minimum switching duration is defined in relation to a modulation index and geometric location near the sector boundaries of the respective inverter voltage space vector diagram.

Abstract: Systems and methods for managing reactive power during low voltage ride through are provided. Responsive to detecting a fault on a power grid, a controller may identify a power regulation mode of the generator system. The controller can switch the power regulation mode to an offset power regulation mode of the generator system responsive to identifying the power regulation mode. The controller may adjust a value of a parameter of the generator system from a normal value to an offset value, wherein the parameter is selected based on the offset power regulation mode. The controller can maintain the value of the parameter as the offset value for a period of time. After the period of time, the controller can modify the value of the parameter from the offset value to the normal value, and the power regulation mode from the offset power regulation mode to the identified power regulation mode.

Abstract: A method for operating a circuit breaker includes: initiating a shutdown process when a fault current caused by body contact or ground contact is detected; and during the shutdown process, reducing a voltage value between a neutral conductor and at least one current-carrying conductor at an output of the circuit breaker to substantially zero from an operating-voltage value according to a predetermined shutdown curve by a shutdown unit. During the shutdown process, the circuit is not suddenly interrupted, but the voltage value is reduced from a starting point according to the shutdown curve and only reaches substantially zero after a predetermined first time period.

Abstract: According to one embodiment, an wireless power transmission apparatus includes a plurality of antennas, a power transmission circuit, a measuring circuit and a control circuit. The power transmission circuit is configured to transmit a beam of a first wireless signal from the plurality of antennas. The measuring circuit is configured to receive a second wireless signal with the plurality of antennas. The control circuit is configured to: detect an object in a direction of the beam based on the second wireless signal received at a plurality of timings; and change a shape of the beam by controlling at least either an amplitude or a phase of the first wireless signal provided to each antenna of the plurality of antennas.

Abstract: A wireless power transmission system includes a first antenna, a second antenna, a controller, a first power conditioning system, and a second power conditioning system. The controller is configured to determine a first driving signal for driving the first antenna based on a first operating frequency, a virtual AC power frequency, a variable slot length, and slot timing, and determine a second driving signal for driving the second antenna based on a second operating frequency, the slot length, and the slot timing. The first power conditioning system is configured to receive the first driving signal to generate the virtual AC power signals at the first operating frequency, the virtual AC power signals having peak voltages rising and falling based on the virtual AC power frequency. The second power conditioning system is configured to receive the second driving signal to generate the virtual DC power signals at the second operating frequency.

Abstract: A fuel cell vehicle according to the present disclosure includes: a fuel cell; a multiphase converter configured to control an output current of the fuel cell; a current sensor provided in each phase of the multiphase converter; an electric load configured to receive power supplied from the fuel cell; and a control unit. The control unit performs, when it detects an excess or a deficiency of electric energy of the electric load, replacement of phases driven by the multiphase converter while the output current of the fuel cell is kept constant, and determines, when the excess or the deficiency of the electric energy of the electric load is eliminated after the replacement of the phases, that an offset failure has occurred in the current sensor provided in the phase that has been driven before the replacement.

Abstract: An AC-AC power converter, such as a motor soft starter, includes an input connectable to an AC source with a disconnect switch, an output connectable to an AC load, and phase lines connecting the input and output to transmit power. In-line solid-state switching blocks are connected between line terminals and load terminals of the AC source and AC load, respectively, such that each phase line includes a solid-state switching block connected thereto. Free-wheeling solid-state switching blocks are connected to the load terminals at one end and together at a common connection at another end, such that each phase line includes a free-wheeling solid-state switching block connected thereto. Each of the in-line and free-wheeling solid-state switching blocks comprises a bi-directional switching block that selectively controls current and withstands voltage in both directions. The switching blocks also provide soft-starter functions, variable speed control, and integrated circuit breaker protection capability.

Abstract: An energy control circuit is provided. The energy control circuit includes an input circuit; an output circuit; an energy storage circuit coupled between the input circuit and the output circuit; and a controller coupled to the input circuit and output circuit for controlling an amount of energy stored in the energy storage circuit and for controlling a waveform generated by the output circuit using energy stored in the energy storage circuit.

Abstract: Power conversion devices with control algorithms that can solve the double frequency harmonic problem are provided, as are techniques for controlling power converters when the instantaneous values of input and output power are not the same.

Abstract: A power system can include a first tap changer for a first regulated transformer, where the first tap changer has a plurality of first positions. The power system can also include a second tap changer for a second regulated transformer, where the second tap changer has a plurality of second positions. The power system can further include at least one first instrument transformer coupled to the first regulated transformer. The power system can also include at least one second instrument transformer coupled to the second regulated transformer. The power system can further include a controller coupled to the at least one first instrument transformer and the at least one second instrument transformer, where the controller adjusts the first tap changer to a first adjusted position among the first positions based on the first measurements of the first regulated transformer and the second measurements of the second regulated transformer.

Abstract: The AC portion of the input of the ultra-sparse partial resonant power converter contains three pairs of forward-conducting-bidirectional-blocking switches connected in a first direction, and two pairs of forward-conducting-forward-blocking devices connected in a second direction to the three pairs of forward-conducting-bidirectional-blocking switches. The second direction is opposite to the first direction. The AC portion of the output of the ultra-sparse partial resonant power converter contains three pairs of forward-conducting-bidirectional-blocking switches connected in a first direction, and two pairs of forward-conducting-reverse-blocking devices connected in a second direction to the three pairs of forward-conducting-bidirectional-blocking switches. The forward-conducting-reverse-blocking devices can be switches or diodes.

Abstract: A method and apparatus for providing multi-phase power. In one embodiment, the apparatus comprises a cycloconverter controller for determining a charge ratio based on a reference waveform; and a cycloconverter, coupled to the cycloconverter controller and to a multi-phase AC line, for selectively coupling an alternating current to each line of the multi-phase AC line based on the charge ratio.

Abstract: A matrix converter includes a power converter, a command generator, and a commutation controller. The power converter includes bidirectional switches each having a conducting direction controllable by switching elements. The bidirectional switches are disposed between input terminals coupled to phases of an AC power source and output terminals coupled to phases of a load. The command generator generates a control command based on a voltage command specifying a pulse width of pulse width modulation control. The commutation controller controls the switching elements by a commutation method based on the control command so as to perform commutation control. The command generator includes a corrector to, when an error in an output voltage is caused by the commutation control, correct the pulse width specified in the voltage command in generating the control command to reduce the error in the output voltage.

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

Abstract: The disclosed technology describes methods and apparatus to convert and control power provided to a precipitator. An example embodiment of the disclosed technology includes a method for providing power to a device. The method includes receiving a first silicon controlled rectifier (SCR) signal and a second SCR signal from a controller device, generating a demand signal by the controller device based on a comparison of the first and second SCR signals, transmitting the demand signal to a power converter device, converting a first power signal from a first base frequency to a second power signal at a second base frequency, wherein the first base frequency is in the range of approximately 50 Hz to approximately 60 Hz and wherein the second base frequency is controlled in the range of approximately 100 Hz to approximately 1000 Hz, and switching the second power signal to the controller device.

Abstract: An electrical circuit, in particular a circuit used for generating electric power, wherein this circuit comprises a generator with n phases, a converter and a transformer to which a p-phase load can be connected. The converter comprises m partial converters, each of the partial converters is composed of p units and each of these units is provided with n/m switching circuits. The switching circuits of the individual units are connected symmetrical to the generator.

Abstract: In general, in one aspect, the invention relates to a method for delivering a controlled voltage. The method involves, during a first electric pulse delivered to a primary transformer, holding a first switching section open to isolate the controlled voltage, where the first electric pulse creates a first magnetic flux in a core of the primary transformer, and where the first magnetic flux generates a direct current (DC) magnetizing current. The method further involves receiving the controlled voltage from a voltage source using the DC magnetizing current at a first switching section, and upon termination of the first electric pulse, closing the first switching section to deliver the controlled voltage to the primary transformer.

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

Abstract: A power-conversion control system includes an inverter, a cycloconverter, and a sliding mode controller. The inverter is operable to receive a DC voltage input and produce a first AC voltage output having a first frequency. The cycloconverter has a plurality of bidirectional switches, and is operable to receive the first AC voltage and to synthesize a second AC voltage having a second frequency that is lower than the first frequency. The sliding mode controller is operable to provide a control signal to command the plurality of bidirectional switches to turn OFF and ON when the first AC voltage is at a zero crossing condition. The sliding mode controller is also operable to selectively adjust the frequency and amplitude of the second AC voltage.

Abstract: In a cycloconverter generator, there are provided, q number of power circuits that supply rectified DC power of a DC power supply unit as operating power to the p (p>q) number of thyristors, and r (p>r) number of thyristor drive circuits that are connected to the q number of the power circuits and drive the p number of the thyristors, wherein the r number of the thyristors drive circuits are individually used to drive in common ones among the p number of the thyristors whose operation is unaffected even if driven at the same timing such that the number r of the drive circuits is made smaller than the number p of the thyristors, thereby enabling to simplify circuit configuration.

Abstract: An apparatus for generating electronic signals for application in subsea electromagnetic exploration. A surface generated high-voltage low-current source signal stabilized at a first frequency is supplied to a deep-tow vehicle (18) via an umbilical cable (16). The high-voltage low-current signal is transformed at the deep-tow vehicle to a high-current low-voltage a.c. signal by a transformer (52) within a cycloconverter (30). A semiconductor relay bridge (104) provides switchable rectification of the high-current low-voltage a.c. signal to provide a quasi-square wave at a second frequency, lower than the first frequency, for supply to a transmitting antenna (22) towed by the deep-tow vehicle. The times of the rectification switching are dependent on zero crossings of the high-current low-voltage a.c. signal. Allowable rectification switching times may be gated to occur only within pre-determined time windows to avoid noise-induced zero-crossing switching.

Abstract: The present invention relates a waveform transformation method and apparatus. It uses multilevel transformation module in series, and the output voltages of power modules at all levels are superposed to get the total output voltage, whereas each power transformation module realizes AC-to-AC direct conversion. The deviation between the output? voltage and setting reference voltage at any time point is made as small as possible by selecting different transformation modules as current working circuit and selecting output voltage waveform of the each different transformation modules. The invention includes outputting n groups of electrical insulating AC and n transfonnation modules connected with AC. The wave transformation method and device of present invention eliminates the intermediate DC stage, so that the circuit is greatly simplified, the cost is reduced obviously and improve working efficiency. It makes voltage and current harmonics to be reduced and obtains higher power factor.

Abstract: The invention in the simplest form is a power conditioning and inverting system for improved and efficient power generation. In particular, the present invention is a modulated dc link scheme that dramatically reduces the switching frequency ripple across the PWM output filter inductor and provides cost, size, and weight reductions, as well as efficiency enhancements. In a preferred embodiment of the present invention, the DC-DC converter control takes a feedback signal proportional to the inverter output voltage. This feedback is “summed” into the primary DC-DC volts command thereby causing the dc bus/link voltage to vary at a multiple of the output fundamental frequency causing the DC link to become a signal at a fundamental frequency voltage with a dc offset. The tooth modulator DC supply tracks the AC output voltage, reducing the difference between the applied DC volts and the AC output volts, thereby reducing inductor core losses.

Abstract: A regenerative converter for a DC motor (55) having an armature (A, B) and a field (57), comprises a conventional three-phase matrix converter (6) including a three-phase bridge (7), the output of two phases being connected (52, 53) across the armature of the motor, the third phase being connected (58) to one end (I) of the DC motor field (57). The other end (K) of the DC motor field (57) is connected (59a) through a plurality of diodes (61-63) to respective phases of the input power.

Abstract: A permanent magnet synchronous motor is controlled using d-axis current and q-axis current along with respective d-current and q-current feedback loops. The speed and position of the motor are determined by injecting a first signal into the d-axis current and observing the response in the q-current feedback loop. Part of the q-current feedback signal is demodulated with a second signal which is 90 degrees out of phase from the first signal. The demodulated signal is preferably sent through a low pass filter before being received by an observer controller. The observer controller outputs a position estimate which is used to modify the d-current feedback signal and a speed estimate which is used to modify the q-axis current.

Abstract: An inverter system providing both an improvement in the voltage utilization factor and a reduction in the switching loss uses a two-phase switching method. In the inverter system, an .alpha.-axis voltage command value; v.sub..alpha.r and a .beta.-axis voltage command value v.sub..beta.r are input to a stop phase selection means. Six sections are judged based on the values v.sub..alpha.r and v.sub..beta.r to select phases for which it is allowable to stop pulse width modulation control in a two-phase switching method. Then, a phase having the largest absolute value of current is selected among the phases for which it is allowable to stop pulse width modulation control using a U-phase current i.sub.u and a V-phase current i.sub.v. This information is a control mode S. Based on these, two-phase switching calculations are performed by a dead-time compensation calculation means and a pulse width modulation generating means. By doing so, the switching loss can be reduced.

Abstract: A three-phase matrix converter for converting AC voltages of predetermined amplitude and frequency into AC voltages of any amplitude and frequency and a method for operating the same, include four-segment switches as main switches which are combined into three switch groups. A resonance capacitance is connected in parallel with each main switch, or an output capacitance of power semiconductors of the main switches acts as a resonance capacitance. An auxiliary commutation device which is provided between three-phase output connections of each switch group has an auxiliary switch constructed as a four-segment switch and a resonance inductance connected in series therewith.

Abstract: To improve operation when there are dynamic load requirements with a direct a.c. converter with a load connected to it in open circuit, the direct a.c. converter is controlled briefly such that the voltage vector resulting from the geometric sum of the phase voltages is increased while the phase relation remains the same.

Abstract: A method and apparatus for AC-to-AC power conversion wherein commutation from one switch in a switching group to a second switch is effected while both switches are enabled simultaneously without causing a short circuit between the phase input lines associated with each respective switch. Each switch in a switching group is bidirectional and polarity-controlled, and may be selectively enabled to conduct only negative-polarity or positive-polarity current, or may be disabled. An overvoltage clamping circuit is also provided with each switch. A switch gating control circuit is employed to provide selective operation of the switches in a particular switch group.

Abstract: A method for controlling the speed of an AC machine (12) is described.The AC machine (12) receives three output phases (A,B,C) supplied from a cycloconverter (10) which is connected to an input supply (R,Y,B) of frequency f.sub.1. The cycloconverter (10) is caused to operate in three modes under control of a microprocessor (25).The first mode supplies the AC machine (12) in the frequency range 0 to f.sub.0, by conventional cycloconverting to generate a near continuum of frequencies.The second mode operates the cycloconverter (10) to synthesize a number of frequency steps in the frequency range f.sub.0 to f.sub.1 from the input supply (R,Y,B) and provides speed control of the AC machine (12) by phase control of the output voltage (A,B,C) between each frequency step.The third mode operates the cyclonverter (10) to be transparent, such that the input frequency f.sub.1 is effectively directly supplied to the AC machine (12) without speed regulation being applied.

Abstract: An engine-driven generator includes an internal combustion engine, a permanent magnet alternator and an AC to AC converter. The output frequency and voltage of the permanent magnet alternator are largely dependent on engine speed and the alternator load. The AC to AC converter converts the speed-dependent alternating current developed by the alternator to another alternating current whose frequency and voltage are largely independent of engine speed. Voltage regulation is provided by varying the engine speed in accordance with the load current. Frequency regulation is provided by frequency dividing the alternator output by an integer divisor that varies in accordance with engine speed. Additional voltage regulation is provided by deleting selected cycles of the alternator output current as needed to maintain the RMS output voltage within predetermined limits.

Abstract: A method and a switching arrangement are provided for regulating a two-dimensional vector of a controlled system with a discrete value final controlling element having a limited switching frequency. The discrete value final controlling element also has limited number of actual-value vectors. A switching arrangement, such as a microprocessor, receives actual values for the two-dimensional vector as well as a reference vector and selects three actual-value vectors that are adjacent to the reference vector. The switching arrangement generates a reference trajectory which represents a sequence of vector settings for the discrete value final controlling element. A switch from one actual-value vector to another takes place when the distance between the two-dimensional vector and a next corner point of the reference trajectory is at a minimum. The resulting mean value of the generated two-dimensional vector is equal to the reference vector.

Abstract: An apparatus and method is disclosed for an improved control system for a series resonant converter for transferring power between a source and a load. The control system comprises a series resonant circuit including a capacitor and an inductor with a first and second switching matrix connecting the series resonant circuit to the source and the load, respectively. A controller selects a combination of switches for transferring power between the source and the load using a single segment half-cycle resonant waveform that produces a final voltage on the capacitor within a preselected boundary.

Abstract: A three-phase converter for polyphase induction motors has an input transformer with primary windings and at least two secondary windings associated with each primary winding, and controlled power semiconductors. Groups of power semiconductors are connected to the secondary windings such that the power semiconductors operate in series with the motor phases.

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: A DC-to-AC electric power converting apparatus including an invertor circuit having a plurality of switching elements, a transformer connected to the invertor circuit, and a cyclo-converter circuit for converting the frequency of the output from the transformer. A carrier signal generator is provided for generating a carrier signal of a predetermined frequency.

Abstract: A method of controlling a cycloconverter, for supplying an AC power having a given frequency to a converter group having at least two cascade-connected converters and controlling a firing angle of each of the converters, thereby converting the AC power supplied to the converter group into an AC power having a predetermined frequency, includes the steps of controlling an output voltage from a converter in one stage of the converter group to obtain an AC output voltage including a synthetic voltage of an AC voltage having an amplitude equal to a difference between a maximum output voltage of the converter and a DC voltage and a predetermined DC voltage in accordance with the polarity of a reference voltage signal having a predetermined frequency, controlling an output voltage from a converter in the other stage of the converter to obtain an AC output voltage obtained by subtracting the output from of the converter in one stage from the reference voltage signal, and continuously varying a voltage value of the DC

Abstract: An electrical circuit receives an alternating input signal and full-wave rectifies the alternating input signal. The rectified signal is then developed by the circuit into an output signal which has a frequency double the frequency of the alternating input signal. The doubled-frequency output signal is then output to a load. Alternatively, the circuit receives a direct current input signal, converts the direct current input signal into a periodically varying output signal, and outputs the periodically varying output signal to a load.

Abstract: An apparatus and method is disclosed for an improved AC--AC series-resonant converters incorporating power pulse modulation with internal frequencies of tens of kHz is applied to a series-resonant converter system for generating synthesized multiphase bipolar waveforms with reversible power flow and low distortion. The high pulse frequency allows the application of the principle of modulation and demodulation for fast system response. Switches are required which have bidirectional current conduction and voltage blocking ability. The conventional series-resonant AC--AC converter applies a total of 24 anti-parallel thyristors. The circuit configuration of the present invention is a series-resonant AC--AC converter with only 12 thyristors. Use of the converter results in a higher efficiency and lower costs.

Abstract: An AC-to-AC converter operating as a current-source between an AC input line and an AC output line connected to a load, for instance an AC motor, includes three groups of bilateral switches controlled selectively within each group so as to generate a quasi square-wave current in each output phase while establishing a DC voltage between two of the output phases at a time, the third phase being idle, the magnitude of the output voltage being controlled in relation to the firing angle of the switches and the frequency being established by controlling the duration of each square-wave alternance. The duration of such alternances is set to 120 degrees of the output wave, followed and preceded by a 60 degree zero-current period.

Abstract: A phase-shifting transformer including main and series transformer units comprises a six-phase core including six independent magnetic circuits, numbered first through sixth from right to left. The combined U-, V-, and W-phase windings of the main transformer unit link with the fifth, third, and first magnetic circuits, respectively. The combined a-, b-, and c-phase windings of the series transformer unit link with the sixth, fourth, and second magnetic circuits. The winding directions of the V- and b-phase windings are reversed with respect to those of other phase windings. Thus, if three-phase voltages 120 degrees apart are input to the main transformer unit, then the phase angles between the main magnetic fluxes generated in any two adjacent magnetic circuits are equal to 30 degrees.

Abstract: In a power conversion system, a DC voltage of a DC power supply is converted into a predetermined high-frequency voltage by an inverter, and a high-frequency low voltage generated from the inverter is converted into a high-frequency high voltage by a transformer. A high-frequency high voltage generated from a secondary winding of the transformer is converted into a predetermined low-frequency voltage by a frequency changing circuit. The commutating operation of the frequency changing circuit is performed by a control circuit in response to the output current of the frequency changing circuit and in synchronism with the starting time of the short-circuiting prevention period of the inverter. As a result, the converted output of the power conversion system is prevented from decreasing.

Abstract: Polyphase inverters for converting AC power into polyphase AC output power typically experience phase shifts due to unbalanced phase loading. The resulting phase error is undesirable and should be eliminated, if possible. In order to overcome the foregoing problem, a control for maintaining N-1 phase outputs at desired angular displacements relative to a reference phase output determines the angular deviation of each of the N-1 phase outputs from the desired angular displacement for such phase output and adjusts a control waveform in time for each of a number of switches based upon the angular deviation of the phase output produced by such switch so that the angular deviations are minimized.

Abstract: A power conversion apparatus comprises an inverter for converting a voltage of a DC power source into AC power having a frequency higher than the commercial frequency, a transformer, fed by the inverter, for outputting AC power, which is adjusted at a desired voltage, a frequency converter, formed by two pairs of two gate turn-off thyristors (GTOs) connected in reverse-parallel, for converting the frequency of the AC power supplied from the transformer into the commercial frequency, and an energy regenerating device having capacitors for absorbing the energy of a spike voltage occurring due to a circuit inductance upon interruption of a current of each GTO of the frequency converter and a bridge circuit, formed by GTOs and diodes connected in reverse-paralel therewith, for switching over the direction of connecting the capacitors with a secondary winding of the transformer in accordance with the polarity of a voltage of the secondary winding in such a manner that the energy stored in the capacitors is regener

Abstract: A three-phase transformer for a cycloconverter comprising three primary windings to which three-phase currents of U-, V- and W-phase are individually applied as inputs, and six secondary windings which are provided for each of the primary windings and so arranged that D.C. components contained in six sets of three-phase signals delivered from the secondary windings are canceled in the respective phases, thereby to prevent D.C. components from being contained in currents which are supplied to the primary winding wound around the main legs of an iron core for the respective phases.

Abstract: In a direct AC to AC converter system the normal rectifier assistance functions are phase modulated by a 30.degree. lag and by a 30.degree. lead, and switching between lagging and leading function is effected at a high frequency according to a duty cycle: ##EQU1## and where .theta. is the electrical angle of the AC power supply, thereby insuring a sinusoidal input current in the system.

Abstract: A digitally-controlled cycloconverter converts a multiple-phase power signal of variable frequency into a single-phase or multiple-phase signal of a lower selected frequency. The cosinusoidal algorithm is utilized to determine the firing delay times, with the analog reference wave used in that algorithm being created from a digitized hardware table. The cosinusoidal algorithm is further simplified by defining the relationship between the analog reference wave and the cosinusoidal timing waves in terms of a two-part piecewise linear relationship which is incorporated into a digital algorithm. The digital algorithm is implemented on a system employing a high-power microprocessor having hardware multiplication and division capability, allowing the algorithm to be used with supply voltages having frequencies about those previously used for cycloconversion. The control logic involved with the firing of a series of thyristors is simplified by utilizing pulse transformers.

Abstract: An AC motor drive apparatus of this invention is constituted by an AC power source, a first circulating current type cycloconverter having an output terminal coupled to the AC power source, a phase-advanced capacitor coupled to an input terminal of the first cycloconverter, a second circulating current type cycloconverter having an input terminal coupled to the phase-advanced capacitor, and an AC motor coupled to an output terminal of the second cycloconverter. The first cycloconverter controls a current supplied from the AC power source to be a sine wave in the same phase as that of the power source voltage, so that a voltage crest value of the phase-advanced capacitor becomes substantially constant. The second cycloconverter supplies a sine wave current of a variable frequency to the AC motor.

Abstract: The present invention discloses a speed control apparatus for an AC motor which vector-controls, for example, a drive current of the AC motor such as an induction motor, synchronous motor and AC commutator motor with a feedback current control loop providing an inverter utilizing a semiconductor element for power amplification such as power transistor and compensates for non-linear current characteristic of the drive current generated by dead time resulting from ignition delay of a semiconductor element with a current compensation control element provided within the current control loop, thereby controlling the rotation speed and command response speed of an AC motor.

Abstract: Three terminal, six and twelve pulse unrestricted frequency changing circuits are provided by inserting controllable bidirectional switching circuits between open star configured coils in multiple phase windings of isolation transformers. Where the switched winding are secondaries of the isolation transformer, interphase transformers are provided between each pair of three pulse circuit groups and additional interphase transformers are required between six pulse circuit groups to provide a three terminal output. Where the switched windings are primary windings of the isolation transformer, the secondary windings are electrically connected in series with each other to provide the three terminal output.