Abstract: A generator/motor system comprises a generator/motor having a primary winding and a secondary winding installed on the motor rotor coupled to a prime mover/load, a main circuit interposed between a power system and the primary winding of the generator/motor, an excitation circuit including a frequency converter inserted between a part of the main circuit and the secondary winding of the generator/motor, a frequency difference detector for determining the difference between the frequency of the power system and a frequency dependent on the rotational speed of the load, and a phase-shift control device for controlling the firing phase of the frequency converter in the excitation circuit by use of a signal from the frequency difference detector as a reference signal.

Abstract: An induction generator/motor system has an induction machine connected at its secondary side to a cyclo-converter. An induced voltage develops when the cyclo-converter pauses during a transient phenomenon occurring in the system. When the induced voltage exceeds a predetermined voltage range which covers the maximum output voltage derivable from the cyclo-converter, the polarity of thyristor converters of the cyclo-converter is switched such that the induced voltage is applied to a thyristor converter to be rendered conductive next in forward relationship therewith, thereby preventing occurrence of an overvoltage.

Abstract: An induction motor system, including a housing, a stator supported by the housing and having a plurality of stator winding conductors positioned about an axis of rotation, and a rotor mounted in the housing for rotation about the axis of rotation, is provided with an integral electronic controller for dynamically and programmably controlling the currents supplied to individual conductors of the stator winding. The stator winding conductors are connected in common at one end and are individually connected to a switching circuit at the other end. The switching circuit supplies positive or negative current pulses through selected conductors. Pulse width modulated signals generated by the controller simulate sine wave energizing signals to provide various operating configurations. By programmed variation of the fundamental frequency, pole configuration, phasing and power level, the rotating speed, starting, acceleration, torque, reversing, dynamic braking and efficiency are dynamically controlled.

Abstract: When a single-phase electric rotating machine has a stator provided with a main armature winding which is composed of, at least, four winding circuits in such a bridge circuit way as can be formed by connecting one set of series-connected two winding circuits in parallel with the other set of series-connected two winding circuits, in the circuit between two outside electric terminals of the main armature winding, and with an exciting winding of which electric terminals are connected electrically with two intermediate electric terminals for the main armature winding, so that the main armature winding may not only supply or be supplied with a load current through the outside electric terminals but also may be supplied with an exciting current from the exciting winding through the intermediate terminals of the main armature winding, two kinds of currents can flow simultaneously in the armature winding, therefore, two different numbers of poles can be produced simultaneously in the stator, the machine can operate

Abstract: An induction motor starting method comprises the steps of supplying a predetermined low-frequency current to the primary winding of an induction motor through a first cycloconverter having its input side connected to a commercial-frequency power source and its output side connected to the primary winding, supplying a voltage of a frequency from zero up to a first frequency through a second cycloconverter having its first input side connected to the commercial-frequency power source and its output side connected to the secondary winding, controlling the first cycloconverter to increase the frequency of the low frequency voltage supplied to the primary winding to the first frequency when the rotation speed of the induction motor reaches substantially a first rotation speed, and disconnecting the output side of the first cycloconverter with the primary winding to connect the output side of the first cycloconverter to the second input side of the second cycloconverter and connect the primary winding to the commer

Abstract: An electric machine which is adapted to function as a motor or generator without any major electrical or mechanical modifications and conforms to conventional electric machine manufacturing practices. This machine has associated therewith, microprocessor controls. There is provided two balanced phase synchronous electrical machines whose moving windings are attached to a common carrier and whose stationary windings are attached to a common body. One of the two balanced phase electric machines is electrically and mechanically designed to be a balanced phase synchronous power motor or power generator at the utility frequency while the other balanced phase electric machine is electrically and mechanically designed for a higher frequency. The high frequency electric machine is driven by a modulated high frequency signal whose modulation frequency is equal to the utility frequency.

Abstract: This method of starting a variable-speed induction motor utilizes a speed control of the induction motor by varying the output frequency from a cycloconverter. The method comprises applying an output from the cycloconverter to the secondary winding of the induction motor while the primary winding of the induction motor is short-circuited during the start-up of the motor, applying a voltage lower than the line voltage to the primary winding when the induction motor is operating within an intermediate speed range, and applying the line voltage within a speed region near the rated speed. This method enables speed control over a wide range, and provides a sufficiently large start-up torque for the induction motor.

Abstract: An electronic system is disclosed for controlling both the ascendant and the descendant speed in vertical machines such as cranes, elevators, etc., in which it is required to lift different loads in a regulated and self-controlled manner, laying aside the traditional mechanical and/or pneumatic control systems. Such control is achieved by virtue of the voltages included in the secondary of the motors of the wound rotor type used in such machines to lift or to bring down different loads, which may vary within a wide range from practically the vacuum to an overload, being possible by such control to select and to maintain both the ascendant and the descendant speed of the load.

Abstract: An electric rotating machine which is adapted to function as a motor or a generator without any major electrical or mechanical modifications. This machine has associated therewith, microprocessor controls. There is provided two balanced phase synchronous electrical rotating machines whose rotors are attached to a common axial. One of the two balanced phase electric rotating machines is electrically and mechanically designed to be a balanced phase synchronous power motor or power generator at the utility frequency while the other balanced phase electric rotating machine is electrically and mechanically designed for a higher frequency. Depending on the modulation type of signal, applied to the stator of the second machine, each of the electrical phase windings of the two rotors are either electrically wired together or electronically connected by a demodulator circuit.

Abstract: A method of controlling the speed of an induction motor comprises the steps of feeding a supply voltage to the winding of a motor stator and obtaining a signal proportional to the motor speed by varying the voltage across the winding of a motor rotor before activating switch thyristors in the rotor circuit. When the obtained signal exceeds a predetermined value, a signal enabling the switch thyristors will be shaped using the same signal. After one of the thyristors is activated, the level of the voltage measured across the rotor winding is reduced to zero or to a value below a predetermined value, thereby causing the signal to cease. Then the entire process is repeated for each of the subsequent thyristors. The speed of several motors may be controlled.

Abstract: A wound rotor motor apparatus includes an energy recovery circuit having a rectifier connecting the rotor circuit to a gated inverter having an input filter for return of rotor power to the three-phase power supply system. A voltage chopper circuit connects the rectifier to the recovery inverter and operates to establish and maintain a constant direct current voltage to the inverter regardless of motor speed. The voltage is greater than the line voltage and is returned at near unity power factor. The chopper circuit is dual gated thyristors. A first thyristor connects an inductor in series to the rectifier. The first thyristor is turned on at the chopper frequency and current flows through the inductor. A commutating thyrister in series with diode is connected in series with a first thyristor and a parallel and back-biasing diode.

Abstract: A load switching circuit for switching two or more transformer taps under load carrying conditions includes first and second parallel connected bridge rectifier circuits which control the selective connection of a direct current load to taps of a transformer. The first bridge circuit is normally conducting so that the load is connected to a first tap through the first bridge circuit. To transfer the load to the second tap, a switch is operable to connect the second bridge circuit to a second tap, and when the second bridge circuit begins to conduct, the first bridge circuit ceases conduction because the potential at the second tap is higher than the potential at the first tap, and the load is thus connected to the second tap through the second bridge circuit. The load switching circuit is applicable in a motor speed controller for a wound-rotor motor for effecting tap switching as a function of motor speed while providing a stepless motor speed control characteristic.

Abstract: SCR devices replace the usual diodes of the rectifier bridge section of a wound-rotor slip-recovery system motor drive, and by selection of the retardation angle of the SCR's between either zero or close to 180.degree., two-quadrant operation is made possible, which includes reverse torque and reverse rotation, while controlling the retardation angle of the power line bridge of SCR's.

Abstract: SCR devices replace the usual diodes of the rectifier bridge section of a wound-rotor slip-recovery system motor drive. By controlling the retardation angle of the SCR devices while controlling the line bridge for acceleration from zero speed to normal speed, the rating of the overall system is reduced. By removing the gating signal of the SCR's while operating at a retardation angle in the range between zero and 90.degree., operation is immediately brought to a stop in case of an emergency.

Abstract: A synchronization arrangement for delaying excitation of the field winding (5) of a brushless synchronous motor until the motor rotor has run up approximately to synchronous speed in which the appropriate moment for applying the field excitation is determined by monitoring two signals respectively representative of the currents in two rectifying devices (11, 15) separately connected, oppositely poled, across the motor field winding.

Abstract: In a separate excitation type inverter device in which an A.C. power source is used as a commutating source, the inverter device is controlled so as to maintain a certain predetermined amplitude of the commutating voltage when the voltage of the A.C. power source is dropped or becomes unbalanced.

Abstract: An adjustable speed pumping system includes a plurality of pumps respectively driven by variable speed A.C. motors each having a power recovery circuit. Each power recovery circuit includes a series connected rectifier bridge, an inductive reactor and an inverter coupled to the secondary winding of the motor which has an A.C. source connected to the primary winding. A fault clearing mechanism is included in each circuit and includes solid state switches in the bridge actuated by a current level sensor coupled to the inverter output. The power recovery circuit also includes current foldback circuitry and secondary gating circuitry coupled to thyristors in the inverter. The power recovery circuits can be connected in parallel with a single motor and the system includes circuitry for sensing the highest amplitude current in the parallel circuits and controlling all circuits with this current.

Abstract: A slip recovery system for a wound rotor induction motor is disclosed in which first and second inverters, connected in series, are coupled to the rotor of the induction motor. A switch is arranged in parallel with the second of these inverters, the switch being in the open position during starting and stopping of the motor, and being closed to short out the second inverter during normal running conditions. Thus, the first inverter need have only a voltage rating of such magnitude so as to satisfy the expected operating range for the wound rotor, while the second inverter need have only a voltage rating of sufficient magnitude to satisfy the additional capacity requirements for stopping and starting service. Thus, lower rated inverter components may be used with lower initial costs as well as concomitant lower operating costs.

Abstract: A control system for an a.c. motor having a polyphase primary winding (stator winding) and a corresponding polyphase secondary winding. The primary and the secondary windings are supplied with current from different frequency converters provided separately for each of the windings. The alternating currents flowing through the primary and the secondary windings are in opposite phase with each other. A position detector is provided for detecting the position of rotor of the a.c. motor. The magnitude of the primary current is controlled proportionally to a current reference signal in dependence on deviation of a speed feed-back signal from a speed reference signal, while the magnitude of the secondary current is controlled to a constant value. The phases of the primary and the secondary currents are controlled on the basis of the rotor position.