Abstract: A control system for an alternating current motor, such as an elevator hoisting induction motor, in response to failure of power supply, such as service interruption, phase open and so forth, performs in a first emergency control mode and in a second emergency control mode. In the first emergency control mode operation, dynamic braking is used to decelerate the motor. On the other hand, in the second emergency mode, triggered while the motor is driven in regeneration mode to recirculate regenerated power to decelerate the motor, a mechanical brake is applied. During second emergency control mode operation, power supply condition is monitored to detect failure of the power supply for switching control mode from the second emergency control mode to the first emergency control mode.

Abstract: An induction motor is controlled using a control device having a current control loop by detecting a current of the induction motor, and by detecting a current error corresponding to a difference between the detected current of the motor and a current command signal of the control device. The current error is processed to obtain a slip frequency. A field speed control command is generated based on the slip frequency and a motor speed of the induction motor.

Abstract: A starting system for a rotary dynamoelectric converter is disclosed. The converter is of the type having three sets of windings wired in either delta or wye configuration. Each set of windings consists of two coils normally connected in parallel within the respective winding, and the converter has three leads connected to the delta or wye configurations. Two of the leads are to be connected to a source of single-phase, alternating current, and a run capacitor is connected between one of the first two leads and the third lead, such that three-phase current can be drawn from the three leads when the dynamoelectric converter is running at its normal operating speed. The starting system comprises a mechanism for connecting the two coils in each respective winding in series with each other when single-phase current is initially connected to the first two leads to start the converter.

Abstract: Apparatus for controlling phase commutation of a brushless DC motor. The apparatus is comprised of a back EMF detection technique to determine the current position of the rotor, an error rejection circuit to prohibit commutation noise from causing errors in determining the present rotor position, a means for determining the next phase set to energize and proper energization timing to maintain a lead angle between the physical rotor position and the magnetic wave, and a means for driving the appropriate brushless DC motor phases with current.

Abstract: An AC induction motor control apparatus includes the determination of the motor torque by one of the use of a torque versus dc input power lookup table for each of selected motor speeds below a predetermined speed and by a mathematical calculation of a plurality of power losses in relation to the dc input power and the inverter frequency for motor speeds above that selected speed.

Abstract: A multiple phase full wave motor drive transistor bridge inverter control circuit in which the base drive power supply for the transistors is transformer isolated from the on/off logic circuits, and the current control function for all of the inverter transistors is performed by a single current regulation circuit. A separate transformer is provided for each phase of the bridge inverter, and the transformer primaries are connected series to form the load of the current regulation circuit. The transformer secondaries supply base current to the upper and lower transistors of each respective phase, and the logic circuits schedule the conduction of the inverter transistors such that one transistor of each phase is always conductive, neglecting dead time. Each of the secondary circuits includes an impedance matching circuit to maintain balanced loading under conditions wherein the inverter transistors are reverse biased due to lagging power factor motor winding currents.

Abstract: There is disclosed a method of controlling a voltage-to-frequency inverter which controls an induction motor by the use of an open-loop system. The motor drives a machine such as a crane, and is braked by a mechanical brake. When the machine is started or stopped, a low-frequency voltage is supplied to the motor so that the motor may produce a torque necessary to hold the load, until the actuation of the mechanical brake ends completely.

Abstract: A solid state starting and control circuit for AC motors employing a single phase power source is disclosed in which the normal motor starting capacitor and speed responsive switch or similar means for energizing and deenergizing the start winding are eliminated by use of an all electronic, sparkless circuit which provides phase displaced current to excite the motor starting winding and in which there is time regulated gradual decreasing of the starting current pulse width to deenergize the start winding.

Abstract: In a three phase full wave type brushless DC motor control system, the neutral (common) terminal (15) is connected to the positive terminal (14A) of a battery (14) with the negative battery terminal (14B) connected to ground comprising a reference terminal (27) for the control system. Pairs of upper and lower controllable switching drive devices (21A-22A, 23B-24B, 25C-26C) are utilized to control current in windings (13A-13C) of the motor (13). Diodes (29-34) are connected across each of the switching devices for handling inductive transient signals. An effective storage capacitor, preferably comprising individual storage capacitors (36-38) connected across each pair of switching devices, is used to store a boost voltage, above battery voltage, which is generated by inductive transient signals.

Abstract: A control circuit for controlling the speed of a tapped winding motor that includes a set of motor speed selection relays, and a normally open relay connected in series with the set of motor speed selection relays. The motor speed selection relays are connected to the tapped windings of the motor for varying speed of the motor. A microprocessor controls energization of the relay windings upon request for a change in motor speed so that the normally open relay is open before and during any change of state of the motor speed selection relays corresponding to the requested change in motor speed.

Abstract: A polyphase machine fed by a pulse-controlled a.c. converter in which the current is controlled between rectangular and sine-shaped waveforms in each half cycle according to the required torque. Independently of the current control, the active number of phase windings is reduced as a function of the rotational speed of the machine.

Abstract: A motor control method is disclosed in which a drive motor is connected to an adjustable frequency power supply in which the frequency of the power supplied to the motor can be selectively varied. While the motor is running at a constant speed as determined by the frequency of the power supplied to the motor, the value of the current being supplied to the motor by the power supply is sensed and an actual current signal representative of said actual current value is produced. A reference current signal which is representative of a selected maximum current value and thereby a maximum load at which the motor speed may be increased is also provided. The actual current signal is compared with the reference current signal and if the former is less than or equal to the latter, an output signal is provided. In response to the output signal resulting from the comparison, the value of the actual frequency of the power supplied to the motor is increased to a preselected value so that the motor speed also increases.

Abstract: An AC motor control system and process useful in such AC motor applications as elevators, storage retrieval machines, cranes and hoists, and other load-carrying and work performing machinery.Two identical and electrically isolated windings are utilized in an AC motor with the current to each winding being controlled through an SCR bank. A first winding, when energized, sets up an electromagnetic field which drives the rotor in a clockwise. A second winding, when energized, drives the rotor in a counterclockwise direction.The use of two separate motor windings eliminates line-to-line electrical short circuit problems so that expensive lock-out circuits, circuit breakers, current feedback detectors and air chokes are no longer required.

Abstract: An AC motor drive using current control instead of the more usual voltage control. The instantaneous inverter phase currents are monitored by sensors 16, 17, 18 and used as feedback to enable the inverter phases to be switched so that each phase current conforms in frequency and amplitude to a phase reference sinusoid produced by a sine wave generator 6. The reference sinusoids are isolated from the feedback comparators 7, 8, 9 with the phase current sensors and comparators having a common reference potential to overcome problems inherent in isolating the sensors.Motor fluxing is optimised at all working frequencies and motor loading by controlling the magnitude of each phase current I, such thatI=I.sub.q .times.f (.phi.)/sin.phi.where I.sub.q is the motor magnetising current, .phi. is the phase angle between the motor phase voltage and current, and f(.phi.) is a function of .phi. which varies between a minimum value and 1. Means for continuously measuring .phi.

Abstract: A starting and operating apparatus and method for a sensorless, brushless direct current motor is disclosed. During start-up, the excitation to the motor is turned off while the slope of the differential back electromotive force of the floating phases is sampled. This indicates when the proper rotation and torque of the motor is obtained. After starting the motor, the apparatus samples the slope of the back electromotive force of the floating coils and finds a zero or predetermined slope condition which has been found to be near the optimum switching point for commutation from one phase to the next. A masking circuit is included to prevent an unwanted commutation immediately after commutating to the next phase.

Abstract: A motor control circuit for a switched reluctance motor which includes a rotor and a plurality of stator coils, and a driver circuit for energizing the coils in sequence, includes a current sensing resistor for detecting a signal proportional to the current in the coils and a slope detector for detecting the rate of change of the current signal with respect to time over predetermined time intervals during which the voltage in the coils is dominated by a term representing back EMF. A variable oscillator is responsive to an integrated output of the slope detector for generating a timing signal for the driver circuit. When the voltage across the coils is dominated by the back EMF term, the current should be substantially constant, but when the rotor is out of phase with the driver circuit, the current signal during this time has a substantially linear slope which is either positive or negative depending upon whether the rotor is leading or lagging the driver circuit.

Abstract: A mechanism such as a camera has an electric driving device being capable of eliminating backlash, is equipped with an electric driving unit, an actuation unit driven by the driving force of the electric driving unit, a gear train for transmitting the driving force of the electric driving unit to the actuating unit, and a control unit for power supply to the electric driving unit for eliminating the backlash generated in the gear train.

Abstract: In a computer-based motor drive, a microcomputer is responsive to a plurality of input signals drived from the motor AC lines whenever contacts, or pushbuttons, commanding specific control operations to be performed, are closed. In such case, opto-couplers convert such AC voltage into a square pulse train which conveys a succession of digital high and low levels. A reference signal is derived, through an opto-coupler form the AC line, which in its high and low logic form is delayed in relation to the input signal trains. By sampling the input signal upon the occurrence fo a falling edge of the reference signal, then at least after the delay existing between the signals, the validity of the input signal is tested by comparing the two successive samples, thereby insuring a true command addressed to the microcomputer.

Abstract: A method and apparatus for preventing a current collapse in a phase not participating in the commutation, of a three-phase block current supplied synchronous machine, while the phase currents of the other two phases are being commutated. A control voltage controlling the synchronous machine is acted upon during the commutation of two phase currents by an additional control voltage such that the average of current drop in the down-commutating phase is equal to the average of the negative current rise in the up-commutating phase. Thus, a method and a circuit arrangement for carrying out this method are obtained with which the torque oscillations of a three-phase-feed drive can be reduced substantially.

Abstract: An AC electric motor can be braked by applying current pulses to the motor when the polarity of the supply voltage is opposed to the polarity of the back electromotive force (emf) voltage across a stator coil of the motor. This current application continues until the motor has stopped. The stoppage is detected by sensing when the current is being applied during every cycle of the supply voltage. Thereafter, the polarity pattern of back emf voltage induced across each of the motor stator coils is sensed. The occurrence of a back emf voltage polarity pattern that remains unchanged for a given number of cycles is detected. Thereafter, a change in this pattern is sensed and the braking current application either ceases or continues for an additional predetermined interval.