Abstract: A synchronous motor control apparatus includes a polyphase synchronous motor, a frequency adjusting circuit responsive to the closing of a power supply switch to generate a frequency control signal for commanding to linearly increase an oscillation frequency from zero up to a given high frequency, a polyphase rectangular oscillation circuit whose oscillation frequency for polyphase rectangular waves is controlled in accordance with the frequency control signal, an energization phase adjusting circuit for generating a phase control signal in accordance with a signal related to the frequency control signal from the frequency adjusting circuit, an energization phase calculating circuit for controlling the phases of the polyphase rectangular oscillation frequency of the polyphase oscillation circuit, and a drive circuit for amplifying output polyphase rectangular signals of the energization phase calculating circuit and applying the same to a field winding of the motor.

Abstract: The invention relates to a control unit to control a continuous cycloconverter of the non-circulating current type which performs frequency conversion of an AC power source using a semiconductor element a to perform commutation by the AC power source and variable speed operation of an AC motor.

Abstract: This invention relates to a motor controller which is so arranged that voltage to be applied to drive windings of a synchronous motor (1) is switched by a plurality of switching elements of a power inverter circuit (4), while the current supply amount to the switching elements is controlled based on pulse width-modulated signals, and which is provided, at a distributing section for selecting energization of said switching elements, with a first logic circuit for applying the pulse width modulation only to the predetermined switching selected from among the switching elements selected during forward rotation of the motor, and a second logic circuit for applying the pulse width modulation to all of the switching elements selected during the reverse rotation of the motor, so as to thereby effect the reduction of electro-magnetic noise during the forward rotation, and to effect the suppression of current during the reverse rotation.

Abstract: A main circuit of an electric vehicle using an induction motor is constituted by an invertor for producing three phase AC power having a variable frequency and a variable voltage and a three-phase induction motor supplied with the AC power by the invertor. The rotational speed of the induction motor is detected and a slip frequency signal is added (in power running) or subtracted (in regenerating running) to or from the rotational speed to control the output frequency of the invertor. On the other hand, the output voltage of the invertor is controlled to be in proportion to the output frequency thereof. The output voltage of the invertor is limited in accordance with notch positions of a master controller of the electric vehicle so as to be provided with a voltage notch stopping characteristic of the conventional electric vehicle.

Abstract: In a load commutated inverter (LCI) motor drive, the motor is started from a rotor rest position by modulating the rotor winding with a field current at a constant rate to induce stator voltages which are detected in terms of signs, so as to identify the rotor rest position. The induced stator voltages are used to select an initial pair of thyristors of the inverter to be turned on in the firing sequence for the chosen direction of rotation under normal operation of the drive.

Abstract: In the prior art, a DC motor is often utilized for controlling speed of servomechanism for its simpleness in operation and excellent control. However, as a DC motor is equipped with brushes and commutators, it inconveniently requires periodical maintenance and inspections in order to keep normal operation. As electric semiconductors such as power transistors along with control technology have made a remarkable progress in recent years, a demand for motors which do not need maintenance is keenly felt. Studies have been conducted on control by DC motors and some have been put into practice. According to this invention, there is provided a synchronous motor which has a small field loss and which does not need slip rings or rotary transformers. Further, there is provided synchronous motor which can be simply constructed at a low cost without using a permanent magnet as a rotor and which can realize a larger capacity, and provided a control unit for the synchronous motor.

Abstract: A reluctance motor control system is stabilized by a load angle feedback control loop provided by a computation of the load angle from sensed voltage and current on the terminals of the motor with the assist of a derived frequency signal. The motor is operated at most efficient load angle in motoring or braking, while the motor voltage is being controlled so as to maintain the desired load angle as the speed and/or load vary.

Abstract: A self-extinguishing element such as a gate turn-off thyristor (GTO) is used for each arm of the inverter. A capacitive load is connected to the output terminal of the inverter. In a region where the output frequency of the inverter is low, the self-extinguishing element is forcibly commutated. In a high-frequency region, where the output frequency of the inverter is higher than that in the low-frequency region, the capacitive load causes the self-extinguishing element to be load-commutated.

Abstract: A speed control apparatus for a synchronous motor is provided with a resolver fixedly connected to a rotor of the motor, which produces a phase modulated signal corresponding to an angular position of revolving magnetic field in the motor, a circuit for converting the phase modulated signal into a rotational speed signal of the motor, a phase compensation circuit for advancing in phase a reference signal in accordance with the rotational speed signal, a multiplier for multiplying the phase modulated signal and a rotational speed instruction signal, a synchronous rectifier for synchronously rectifying the output of the multiplier by an output of the phase compensation circuit, and a current control loop circuit for receiving an output of the synchronous rectifier and for producing a signal having a phase angle delayed as much as the phase angle is advanced in the phase compensation circuit.

Abstract: In a control system for a power converter driving a synchronous motor, comprising a controllable rectifier and an inverter of a load commutation type, a speed target is passed through a variation rate limiter for limiting the variation rate to produce a speed reference varied to follow the speed target but within a limited rate. A speed controller is responsive to the speed reference and the detected speed of the motor for producing a current reference. A current control circuit is responsive to the current reference and the detected current of the rectifier for adjusting the average current through the rectifier thereby to reduce the deviation of the detected speed from the speed reference. The current control means comprises means for causing intermission of the current through the rectifier for intermission commutation of the inverter when the detected speed is below a predetermined threshold.

Abstract: A load-commutated inverter for operating a synchronous motor having two sets of 3-phase windings. The difference of phase angles between the two sets of the 3-phase windings is 30 degrees. The load-commutated inverter is provided with two sets of inverters and a control circuit. Each of the inverters, is formed of thyristors. The inverters are coupled respectively to the 3-phase windings of the motor. The commutation of each of the thyristors is controlled in accordance with a given advanced control angle. The control circuit is coupled to the inverters and is responsive to a commutation overlapping angle of currents (e.g., IU1, IV1 in FIG. 4A) supplied from the inverters to the 3-phase windings of the motor. The control circuit adjusts the given advanced control angle so as to retain a relation:u+.gamma.*.ltoreq.30 degreeswherein u denotes the commutation overlapping angle and .gamma.* corresponds to the reverse-biasing time applied to each of the thyristors.

Abstract: The operation of an interior permanent magnet synchronous motor is extended to the constant horsepower regime by causing the stator current vector to follow the voltage-limit ellipse in the counter-clockwise direction. The error between commanded stator current and actual stator current is determined to signal a saturation of the inverter and the commanded stator current is modified to reduce the error.

Abstract: This disclosure relates to a system for stabilizing a permanent magnet synchronous motor that does not have a rotor starting cage or windings. The system includes a dc source, an inverter connected to the dc source for converting the dc to a multi-phase ac, and an ac synchronous motor connected to receive the multi-phase ac, the motor being constructed without a starting cage or winding. The system further includes means for sensing variations in the motor power angle, and a control circuit connected to respond to the variations and to cause the inverter output to vary such as to generate an ac component of torque that leads in phase the power angle variations at the natural frequency of the rotor of the motor. The inverter output may be varied by modulating the applied frequency, the dc bus current to the inverter, or the inverter phase angle.

Abstract: A control system for an AC motor to be driven by an inverter, wherein a control lead angle .beta. of the AC motor drive current is controlled based on the detection of an actual overlapped angle, a set overlapped angle, a detected motor speed, a detected magnitude of the acceleration-deceleration rate of motor speed, a detected amount of current from a power source and/or a detected magnitude of the change rate in the current from the power source.

Abstract: A synchronous motor control system includes a sensor (112) for sensing the rotational angle of a synchronous motor (101), and a control circuit (108) for generating a sinusoidal value corresponding to the rotational angle sensed by the sensor (112) and for multiplying the sinusoidal value by an effective value current command. The multiplied output of the control circuit (108) is applied as a current command value to the armature winding of the synchronous motor (101). In this case, the arrangement is such that the control circuit (108) compensates the sensed rotational angle by the actual velocity of the synchronous motor (101) or by a rotational command velocity for the synchronous motor.

Abstract: A synchronous motor control system for preventing a torque efficiency reduction on high-speed rotation and acceleration to produce a torque efficiently at all times. The synchronous motor control system detects when inverter drive signals for controlling currents supplied to the synchronous motor exceed a physical saturable quantity of an inverter, and corrects current waveforms applied to the synchronous motor to make sure that they are sine waves at all times.

Abstract: For starting a rotatable 3-phase a-c electrical machine of the synchronous type, the stator windings of the machine are connected to an electric storage battery via a controllable electric power converter, and the d-c field winding is connected in series with the stator windings by inserting it in the load current path between the converter and battery. Field weakening resistance is connected in parallel with the field winding. The converter includes a plurality of electric valves (thyristors) that are cyclically turned on in a predetermined sequence in synchronism with alternating voltages developed at the line terminals of the stator windings.

Abstract: This invention relates to a motor control circuit for a permanent magnet motor having a rotor and motor windings. A motor winding transformer circuit is coupled to motor windings and provides an output signal representative of the magnitude and direction of the real current present in the motor windings. A rotor speed/position sensing circuit provides an output signal representative of the motor speed and direction.

Abstract: A power conditioner having a source and load converter each using a phase-locked loop to control their respective converter firings achieves synchronization with a supply mains by determining the phase error between supply mains and motor voltages by obtaining the instantaneous difference between the output signals of the source and load phase locked loops. This phase error is passed through a simple gain and summed with a speed regulator setpoint, which now becomes an inverter frequency regulator with the nominal setpoint being the supply mains frequency. The voltage amplitude error between the supply mains and the motor is obtained by comparing the absolute value of the source voltage with the properly scaled absolute value of the integrated motor voltage and this error signal is input to the flux regulator in a synchronous or induction motor controller in place of the normal input when not synchronizing.

Abstract: In a 3-phase third harmonic auxiliary impulse commutated electric power inverter, during a commutation interval the firing signal for the oncoming main valve of the inverter is delayed for a programmed interval of fixed duration after the commutation capacitor voltage changes polarity, whereby the peak voltage on the capacitor can automatically vary with the magnitude of load current.

Abstract: In a 3-phase third harmonic auxiliary impulse commutated electric power inverter the d-c terminals of which are connected, via a circuit having appreciable electrical inductance, to a voltage source comprising a battery, the commutation capacitor is precharged by cyclically manipulting the conducting periods of selected main and auxiliary valves of the inverter so that a series of discrete pulses of capacitor charging current flow from the battery through a path comprising the aforesaid circuit, part of the inverter load circuit, and the capacitor, with alternate pulses of current traversing the capacitor in one direction and intermediate pulses traversing it in the opposite direction. Such action continues for a sufficient number of cycles to "ring up" the capacitor to a voltage magnitude more than five times higher than the battery voltage.

Abstract: Highly reliable and consistent starting is achieved by first initializing the rotor position, namely establishing the rotor in a known starting position. This is accomplished by gating on two pairs of SCRs in sequence and supplying current pulses through the gated SCRs to the stator of the motor to rotate the rotor to a first position and then to a second position, the rotor coming to a complete stop in each of those positions. The rotor aligns itself with the magnetic field created by the stator in each position and any ambiguity in the rotor position is eliminated. Thereafter, the inverter is operated asynchronously in a second mode with predetermined pairs of the inverter SCRs being sequentially gated into conduction at an increasing frequency to current pulse energize the motor to effect step-by-step rotation of the rotor at a faster and faster rate, the motor current being reduced to zero at the termination of each energizing pulse to force commutate the conducting pair of SCRs.

Abstract: Apparatus and method for controlling a synchronous motor driving a square-law torque load at variable speeds by employing a frequency changer. The armature voltage Va may be controlled so that the ratio Va/N at motor speeds above a predetermined value is greater than Va(100)/N(100), where N(100) is the rated speed of the motor and Va(100) is the armature voltage at that speed. Below a predetermined speed, the armature voltage may be controlled so that the ratio Va/N is less than Va(100)/N(100).

Abstract: To reduce adverse effects due to a dead zone in a pulse-width modulation circuit provided for avoiding short-circuiting in an inverter circuit, distortions of sine wave currents generated when low-frequency current commands are given, sound produced due to the excitation, and torque variations, a synchronous motor drive apparatus has been provided.

Abstract: A circuit for energizing and controlling a synchronous rotary machine which operates at variable speed and is fed by controlled static switches, wherein the stator of the rotating machine has a plurality n of polyphase windings where n is at least equal to two, each polyphase winding being fed by a static AC-AC converter (A, B) which constitutes an autosychronous inverter having a mains bridge (PRA, PRB) and a machine bridge (PMA, PMB) connected to each other by first and second DC conductors, and wherein the circuit has means for controlling the mains bridge of each converter in such a way that the sum of the DC currents (IA+IB) in said conductors of all the converters is proportional to a reference average current value.

Abstract: A control apparatus for thyristor motor comprises a voltage detector (27), a speed detecting circuit (600) and a correction circuit (800). The voltage detector (27) detects DC voltage (E.sub.d) supplied to an inverter circuit (200). The speed detecting circuit (600) detects the rotational speed of a synchronous motor (3) and provides speed voltage (E.omega.) proportional thereto. The correction circuit (800) detects a difference between the detected DC voltage (E.sub.d) and the speed voltage (E.omega.) and provides a correction signal to an excitation circuit (700) when a difference is detected. The excitation circuit (700) corrects field current in response to the correction signal so that the DC voltage (E.sub.d) and the speed voltage may be equal. Thus, a proportional relation can be maintained between the instructed torque and the generated torque.

Abstract: A control circuit of a synchronous motor with two induction windings, including an electrical power supply assembly (5), two oscillators (2,3) whose outputs are connected respectively to the windings of the motor (1), an intermediary circuit (4), connected on one side to the power supply and on the other to the oscillators, and a central unit for control of the thyristors.The electrical power supply assembly (5) delivers a current of a given unique polarity, and has its output terminals connected by means of a freewheel branch including at least one freewheel diode (6) whose cathode is connected to the positive terminal.

Abstract: A relatively simple inverter-motor system, comprising a minimum number of circuit components, is provided by employing a voltage-controlled thyristor inverter which in turn drives a synchronous motor having a leading power factor. With the motor current leading the motor voltage, the thyristor switching devices will be motor-commutated, thereby precluding the need for any auxiliary commutating elements or circuits to effect forced commutation. Since, with a leading power factor, the current through a conducting thyristor falls to zero before the thyristor has to be switched off, ample turn-off time is provided. Furthermore, as compared to a conventional forced commutated voltage source inverter, the customary reactive diodes, usually shunting the switching devices in an inverter to permit the flow of reactive motor current, are not necessary.

Abstract: Stabilized operation of a damperless synchronous motor, which is driven by a voltage source inverter energized by a d-c bus voltage, is obtained under transient conditions, such as during sudden variations of load torque, in order to maintain the torque angle in the motor relatively stable at all times and within the stability limit. This is achieved by employing transient changes in either the d-c bus voltage, the d-c bus current or the motor voltage, which changes reflect transient variations of the torque angle, to rapidly adjust the inverter frequency as necessary to hold the torque angle reasonably constant. For example, if there is an abrupt load increase on the motor, the bus voltage tends to drop and the motor tends to slow down, the torque angle thereby tending to increase.

Abstract: A synchronous motor is driven by a plurality of inverting circuits. The inverting circuits are controlled by signals from a position detecting circuit coupled to the shaft of the synchronous motor so as to produce output current signals from the inverting circuits which are shifted by a certain angle from each other.

Abstract: A method and a means for feeding electric energy to a portable power tool is based on a principle according to which the brushless AC motor of the tool is individually supplied with power from a solid state inverter type power supply by which the amplitude and frequency of the AC current are automatically and individually adapted to the instantaneous load conditions experienced by the motor.

Abstract: A method for operating a frequency converter of the type having an auxiliary commutating device for commutation at speeds which are lower than a machine-related minimum speed of operation. In a first speed range which begins at speed zero, the thyristors of a three-phase bridge of the inverter are commutated cyclically, as customary, six times per revolution of the machine. In a second speed range which is adjacent to the first speed range and below the machine-related minimum speed of operation, only every second commutation is executed. In embodiments of the invention wherein there is provided a third speed range which is adjacent to the second speed range and extending up to the machine-related minimum speed, only every third commutation is executed. In this manner, an auxiliary commutating device having a predetermined frequency limit can be utilized at speeds corresponding to two or three times the speed at which such an auxiliary commutating device could be used in prior art systems.

Abstract: A microcomputer for use with a direct current machine drive system processes machine drive system currents and voltages to compute real time machine efficiency. From real time machine efficiency, the microcomputer determines optimum, that is to say, desired machine armature current and optimum machine air gap flux. Machine armature current and field current are regulated, respectively, by controlling machine armature voltage responsive to the difference in magnitude between optimum armature current and actual armature current, and by controlling machine field voltage responsive to the difference in magnitude between optimum machine air gap flux and actual machine armature flux, respectively, to assure machine operation at maximum efficiency irrespective of machine load conditions.

Abstract: Apparatus for controlling wheel slip in a locomotive driven by d.c. motors which receive power from a diesel driven generator, has sensors which provide signals representing speeds of different driven wheels to a velocity unit. The velocity unit derives a differential signal representing the difference between the highest and the lowest wheel speeds. A sensor detects current or power in the generator output and the signal from this sensor is sampled periodically and the latest two sampled values are stored. The sampled values are compared to provide a creep reference signal. The differential signal and the creep reference signal are compared and the resulting difference signal is used to control generator output to maximize current during acceleration.

Abstract: A link regulator is disclosed for providing a regulated voltage over a wide range of input frequencies and load currents. The frequency of an internal VCO and the input frequency are phase compared to provide a reference error signal. The unregulated DC voltage is integrated for a duration proportional to the error signal. This duration controls a series switching element to provide a constant volts/seconds. The output of the series switching element is filtered to a DC voltage that controls the frequency of the VCO. The DC voltage is proportional to the error signal, thus providing a feed forward system to regulate the DC voltage. During the period when the series switching element is not conducting, a shunt switch presents a low impedance to the input of the filter to clamp the input to ground. This allows for operation over a wide range of load currents without losing regulation.

Abstract: Apparatus for controlling a salient-pole machine includes a stator current control element to make the stator current i.sup.S follow preset desired values i.sub..phi..sup.S*. A field current control element develops from preset desired flux values .psi.*, from the flux signal output of a flux computer (direction .phi..sub.L) and from an inductance parameter (the shunt inductance X.sub.q of the machine) a fictitious field current value signal i.sub.O.sup.E*, which represents the field current value which would be used to control a hypothetical nonsalient-pole machine. This signal i.sub.O.sup.E* is modified by a correction factor derived from the product of the longitudinal component of the flux .psi..sub.d (from the flux computer) and the different between the reciprocals ((1/X.sub.q)-(1/X.sub.d)) of the shunt and series inductances of the machine, to give a field current control signal that accounts for the asymmetry of the salient-pole machine.

Abstract: Control system for driving a synchronous motor at a speed greater than a rated speed with a rotational speed detector for the rotor mounted on the motor, rotational position detector for detecting the rotational position of the field pole of the motor, an error signal generator which produces the difference between a desired speed signal and an actual rotational speed signal, and a calculating device for calculating armature current component values Id, Iq and power-factor .phi..

Abstract: A load commutated inverter synchronous motor drive system wherein a thyristor firing control of the inverter is determined by the amplitude of pesudo flux waveforms which are derived from the integral of the line voltages coupling the inverter to the motor being driven. A firing strategy is provided based on the premise that optimum thyristor firing in a load commutated inverter operating at a leading power factor occurs at a point just below the peak of the forthcoming pseudo flux waveform which point comprises an amount of volt-seconds necessary to effect current commutation plus a nominal safety margin. The determination and control is implemented, preferably, in a software phase lock loop but can, when desirable, be implemented in hardware.

Abstract: A control system for a load commutated inverter AC synchronous motor drive provides an operational shift in the event of an increase in motor terminal voltage V.sub.TERM above a preselected reference level. Under such an increase in terminal voltage, control is transferred from a condition where torque is controlled by current and the terminal voltage is uncontrolled to a condition where the load current, e.g., the DC link current I.sub.L flowing between a source side thyristor converter (AC to DC) 12 and a load side thyristor inverter (DC to AC) 14 is utilized to control the motor terminal voltage while the firing angle of the thyristor inverter 14 is used to control the motor torque. This involves increasing the minimum load or motor drive current for a desired torque while adjusting the inverter firing angle from a previous value, so that the desired torque is provided at a higher current I.sub.L and lower terminal voltage V.sub.TERM than before.

Abstract: The load side converter or inverter in a load commutated inverter motor drive, including a source side AC to DC converter coupled to a DC to AC converter via a DC link circuit, is adapted to have at least three and preferably four modes of operation for bringing an AC motor load, and more particularly a synchronous motor, up to speed. In the preferred embodiment, the first mode constitutes an idle mode wherein the converter thyristors are maintained in a non-conducting state until commanded for normal operation. The second mode constitutes an initial start-up mode which assumes no knowledge of initial rotor position of the motor and simply utilizes a fixed low frequency firing signal to sequentially gate the thyristors using forced commutation to commutate the off-going thyristor.

Abstract: A current limiter for a load commutated inverter-synchronous motor drive including a source side AC to DC converter (12) and a load side DC to AC converter (14) coupled via a DC link circuit including an inductor (16) wherein a torque reference signal (TORQUE REF) generated for controlling both the converters is limited in response to the peak value .psi..sub.MAX of the pseudo flux waveform (.psi..sub.ab, .psi..sub.bc, .psi..sub.ca) which is derived from the integral (.intg.) of the motor terminal voltage (v.sub.ab, v.sub.bc, v.sub.ca) in order to limit the motor stator current I.sub.s to a value corresponding to the region of peak output torque T.sub.MAX obtainable for the motor field current I.sub.f applied. Control of both the source side converter (12) and the load side converter (14) by the torque reference signal operates to control the magnitude of the current I.sub.L in a DC link circuit which corresponds to the motor stator current I.sub.

Abstract: Apparatus for controlling a static AC/AC thyristor converter which supplies power to a synchronous rotating machine (7) at a variable frequency. The converter comprises a "machine" bridge (PM) and a "mains" bridge (PRA, PRB) connected to each other by a first conductor (9) and by a second conductor (10), together with an auxiliary connection (8) which connects the neutral point of the synchronous machine to a point (11) at the "mains" bridge end via which point current can be returned to a transformer which supplies power to said "mains" bridge. The control apparatus comprises means for controlling the "mains" bridge in such a way that the sum of the currents IA+IB of said first conductor (9) and of said second conductor (10) interconnecting the "machine" and "mains" bridges are equal to an average reference current.

Abstract: A control system for an AC motor drive including a source side converter and a load side converter coupled together by means of a DC link circuit wherein the current in the DC link circuit is controlled by either the source side converter or load side converter depending upon which converter is capable of control. This is achieved by crosstieing a signal from the normal regulating path in the source side converter control to the alternate regulating path in the load side converter control. This signal is chosen to be indicative of the source side converter controller being unable to control current, and may be derived from current error. This signal operates to alter the firing angle of the load side thyristor bridge to regulate the DC link current in the event the source side converter is unable to maintain the required current regulation.

Abstract: Regulation of inverter-machine drive system torque and frequency in accordance with operator commands is achieved by the use of an improved, microcomputer-based, control apparatus. At machine frequencies less than a preselected machine frequency, inverter pulse width modulation signal pulses and half cycle polarity signal pulses are supplied by the control apparatus to the inverter to regulate the duration and conduction sequence, respectively, of inverter switching devices in accordance with pulse width modulation signal data computed by equilateral triangulation and stored half cycle polarity signal data. At frequencies above the preselected machine frequency, when computation of inverter pulse width modulation signal data becomes impractical, inverter pulse width modulation signal pulses are synthesized from stored data. This achieves simplification of control hardware and provides improved machine drive system performance.

Abstract: An apparatus and method for accelerating textile winder synchronous motor drives from standstill to rated running speed wherein a synchronous motor is first accelerated asynchronously to a first intermediate speed, then decelerated to and synchronized at a second intermediate speed, then accelerated synchronously to rated speed, while thereby limiting current drawn by the motor to levels not exceeding rated current. The method is automatically followed using apparatus which varies motor input frequency responsive to a predetermined sequence of control signals supplied from a signal source via a transient response profiler which converts sudden changes in signal strength to smooth, gradual changes. As more specifically described herein, only two controllers are needed, and a switching network including time-delay devices selectively supplies one signal or the other via an integrator to a variable frequency converter.

Abstract: Apparatus for controlling a permanent magnet AC synchronous motor supplied by a forced commutated inverter that does not use a mechanical shaft position sensor. A control loop regulates an inverter frequency and maintains inverter synchronism with the motor using electrical angle feedback signals developed from measured flux signals that have been phase shifted.

Abstract: A marine propulson system is described that includes a gas turbine, an alternating current generator, a fixed pitch propeller, a synchronous motor and a frequency converter. The frequency converted is connected electrically between the generator and motor during starting and reversal procedures when the motor would normally have to operate as an induction motor. Means are provided to brake the system dynamically to speeds within the capacity of the frequency converter. At speeds within the frequency converter's design capacity, the motor can be operated synchronously while it is running at a speed below the minimum operating speed of the turbine and generator.

Abstract: A plurality of slots are disposed at equal angular intervals on one portion of a circular ring-shaped field magnet fixed to a motor's rotor to run radially of the magnet. Alternatively, short rods made of a soft magnetic material may extend radially outwards from the lateral surface of the magnet to form the slots between them. Three magnetic sensor elements are disposed at equal angular intervals of 120 degrees on a motor's stator to face successively the slots during the rotation of the rotor.

Abstract: An alternating current machine drive system, comprised of an alternating current machine and an inverter configured of a plurality of pairs of transistors with the transistors of each pair coupled in series-aiding fashion and each of the pairs of serially coupled transistors connected across a direct current source, is controlled in accordance with inverter current. The transistors of each inverter transistor pair are alternately rendered conductive to supply alternating current at the inverter output in accordance with a current error signal, proportional to the difference in magnitude between actual inverter phase current and a sinusoidal reference signal, with the conduction state of the transistors of each pair reversing each time the current error signal exceeds an upper and lower hysteresis limit, which limits vary in accordance with actual inverter phase current.

Abstract: An inverter (34) which provides power to an A.C. machine (28) is controlled by a circuit (36) employing PWM control strategy whereby A.C. power is supplied to the machine at a preselectable frequency and preselectable voltage. This is accomplished by the technique of waveform notching in which the shapes of the notches are varied to determine the average energy content of the overall waveform. Through this arrangement, the operational efficiency of the A.C. machine is optimized. The control circuit includes a micro-computer and memory element which receive various parametric inputs and calculate optimized machine control data signals therefrom. The control data is asynchronously loaded into the inverter through an intermediate buffer (38). In its preferred embodiment, the present invention is incorporated within an electric vehicle (10) employing a 144 VDC battery pack (32) and a three-phase induction motor (18).