Abstract: An electronic starting circuit for a single-phase electric motor is disclosed in which the motor has a first, and possibly a second, main winding and has an auxiliary winding used for starting. The voltage across the auxiliary winding increases as the motor speed accelerates and is used as a sensing signal. This signal is applied through an amplifier to a peak detector which determines the peak DC output and compares it with a reference voltage. When the reference voltage is the larger, then an auxiliary switch connected in series with the motor auxiliary winding is closed for starting of the motor. When the peak DC output voltage from the peak detector exceeds the reference voltage, the auxiliary switch is opened. Instant reversing of the motor is possible by discharging a capacitor in the peak detector at the time of reversal so as to re-energize the auxiliary winding. The circuit also operates on a two-speed motor.

Abstract: An electric motor is braked by sensing the polarity of voltage of the alternating electricity for powering the motor and sensing the polarity of the voltage induced in the motor by the back electromotive force. When these polarities are opposite the electricity is applied to the motor to generate a braking torque. The application of the electricity is stopped a given interval after it begins to be applied during consecutive voltage cycles. This interval is derived from the time period between when braking commenced to when the electricity was applied during consecutive cycle.

Abstract: Adaptive control is used in an asynchronous motor drive. A reference model based on the model equation of the motor is combined with an adjustable model responsive to the direct and quadrature components of the current and to an estimated speed. An adaptive mechanism counting in a P-I amplifier expands to the direct deviation between the direct and quadrature components of the flux outputed by the two models and generates a feedback signal representing the estimated speed. The adjustable model reacts to such feedback signal so that the estimated speed readily becomes the actual speed of the motor. As a result, a tacho-less AC motor drive is obtained in which under any running conditions the motor immediately takes the required speed.

Abstract: An inverter including a manual torque boost mechanism for outputting a constant voltage/frequency pattern by manually setting a constant voltage corresponding to a constant frequency regardless of the magnitude of a current value of a drive power supplied to a rotation drive apparatus such as a motor and an auto boost mechanism operative based on the constant voltage/frequency pattern set by the manual torque boost mechanism for automatically correcting the voltage/frequency pattern according to the magnitude of the input current of the rotation drive apparatus and is capable of compensating for the torque decrease of the input current by use of the manual and auto torque boost mechanisms especially when the input current of the rotation drive apparatus is in the low-frequency range.

Abstract: The subject invention is an electric motor brake which uses a simplified circuit enabling a timed injection of DC voltage into the motor windings of an induction motor. This DC voltage acts as a dynamic braking force and will bring the rotor, and whatever is connected to it, to a stop in a rapid fashion. An additional advantage of the invention is that it may be constructed and used as a stand alone device which may be attached to any electrical induction motor to achieve the desired braking effect. A further feature of the invention is the provision of a timing circuit that it is designed to be user adjusted to achieve the maximum possible effect rather than using a fixed design which would result in a compromise in order to be suited for wide usage.

Abstract: The present invention is directed to a method and apparatus for connecting a static inverter to a free-running motor, wherein the inverter is supplied with D.C. power by a regulator-controlled rectifier. An oscillator connected to both the rectifier regulator and the inverter governs the frequency of the three-phase inverter output, while voltage feedback from the inverter output to the rectifier regulator is employed to establish a proper volts/hertz output characteristic in the inverter output waveform. During the connection process, a synchronizing circuit causes the oscillator to generate a high pulse rate signal which raises the inverter output frequency to a level above that associated with the rotational speed of the free-running motor. Simultaneously, the D.C. output of the rectifier is clamped by the current regulator to current-limit the inverter output. The inverter is subsequently connected to the free-running motor and the inverter output frequency is allowed to decrease gradually.

Abstract: The present invention is a load sensor for use in an automatic portal operator such as an industrial gate operator. An induction motor is employed to move the gate. The power factor of the AC electric power supplied to the induction motor is monitored. A safety operation is triggered when the power factor indicates the motor load is greater than a predetermined amount, as when an obstruction is encountered by the gate.

Abstract: In a motion control apparatus for an induction motor, an inclination of acceleration/deceleration curve representing an increase/decrease per unit time in rotation speed of the induction motor is changed in accordance with the value of an angular frequency .omega.s corresponding to a slip speed of the induction motor.

Abstract: A load state detecting apparatus of an induction motor having two coils, the apparatus having a drive voltage supplying unit for supplying a drive voltage to the coils in the induction motor, a phase difference detecting unit for detecting a phase difference between the drive voltage supplied across the coils of the induction motor and a current flowing through one of the coils upon application of the drive voltage and for generating a phase difference signal, and a load state detecting unit for comparing the phase difference signal generated by the phase difference detecting unit with a predetermined reference value and generating a signal depending on a load state of the induction motor.

Abstract: A starting device for an automobile motor in which an asynchronous motor (23) is used both as starting motor and generator. A number of solid state switches (10), forming part of an inverter, is arranged on a metal bar (7) extending along the stator (4) of the motor. The metal bar is connected to one terminal of a voltage supply (21). The stator conduits (9) are connected to a solid state switch and to the other terminal of the voltage supply.

Abstract: A manually controlled positive and reverse circulating fan is used in room, usually, when in summer to blow air is downward so that the cool air at the lower level can be spread into every corner of the room. In winter, the fan is operated reversely and the warmer air at higher level can be spread evenly down in the room, thus the room temperature can be kept even and the energy can be saved. However, because of the limitation of the room space shape, there are still spaces that the air flow can not reach. This design, with a periodic positive/reverse switch operation, controls the ceiling fan to operate positively or reversely in periodicity so that it may further improve, the function of stirring the air evenly. This design can be used also ventilators/for air intake/exist as well.

Abstract: A method of controlling current in an AC motor to inhibit small torques on an unloaded motor output shaft and to improve buildup of steady-state operating flux in a rotor includes supplying current to the stator windings through a plurality of semiconductor switches, operating the semiconductor switches to supply a plurality of gradually increasing currents to the stator windings over a time interval corresponding to approximately one rotor time constant to bring flux in the rotor up to approximately 10% of a steady-state operating flux in the rotor, operating the semiconductor switches to supply a current that is the maximum current rated for pulsed operation of the semiconductor switches for a time interval over which a product of current and time is sufficient to produce steady-state operating flux in the rotor, and then reducing the stator current to a level for maintaining steady-state operating flux in the rotor. A microelectronic apparatus for carrying out the method is also disclosed.

Abstract: A solid state starting system for electric motors having main and start windings of the capacitor start, capacitor start-capacitor run and split phase types uses a triac serially connected to the start winding. The system turns on the triac upon energization of the motor from an at rest condition and measures the locked rotor value of either the main winding current for any of the above motor types or start winding voltage for the capacitor start, capacitor start-capacitor run motor types. The system stores that valve as a calibration value and then measures subsequent values and turns off the triac when the subsequent values reach a selected proportion of the calibration value. The system re-energizes the triac upon further subsequent measured values reaching a selected cut in value relative to the calibration value which is indicative of an overload or stall condition. The calibration value is retained for a given period of time following a loss of power to provide desired starting characteristics.

Abstract: An AC Motor Speed Controller used to control the Speed, Torque and Horsepower of an AC motor. It allows the speed of the motor to be adjusted to the desired level and is calibrated to develop the desired torque, either automatically through load feedback or through a predetermined or preset level. It also allows for excessive torque to be developed under starting and acceleration conditions while providing for controlled deceleration with proportional braking of the inertia load.

Abstract: An apparatus according to this invention includes a DC power source, a DC-AC power converter having an output terminal coupled to the DC power source via a DC reactor, a high-frequency, phase-advanced capacitor coupled to an input terminal of the DC-AC power converter, a circulating current type cycloconverter having an input terminal coupled to the phase-advanced capacitor, and an AC motor coupled to the output terminal of the cycloconverter. In this apparatus, a current supplied from the DC power source is controlled by the DC-AC power converter, so that a crest value of a voltage applied to the phase-advanced capacitor is substantially constant. The cycloconverter controls to supply a sine wave current of a variable frequency (0 to several hundred Hz) to the AC motor.

Abstract: A control circuit for operating a synchronous motor with a polyphase armature winding in a d-c voltage network comprises a switch device for successively connecting the winding phases with the network, a switch signal generator which produces switch signals for the switch device, a logical stage for logically loading the switch devices with said signals. The circuit also includes a voltage/frequency converter, a starting device and a re-starting device. The converter generates a pulse succession which is increased by the starting member from zero to a predetermined value to re-start the motor when its current exceeds a predetermined value.

Abstract: An electric motor is coupled to the power lines by thyristors. The motor is braked by triggering the thyristors at the proper times to produce a electro-magnetic field within the motor which opposes the residual magnetic field of the rotor. The proper time to trigger the thyristors is determined by comparing the polarity of the voltage across the power lines to the back emf voltage from the motor. The thyristors are triggered when these two voltages have opposite polarities. The braking circuit also regulates the duty cycle of the thyristors to control the magnitude of the current applied to brake the motor.

Abstract: A method and an arrangement for controlling an asynchronous motor fed via a frequency converter. The control is accomplished with a model implemented in a microcomputer which is provided with data derived from the characteristics of the motor set forth on the rating-plate of the asynchronous motor along with data derived directly from the operating characteristics.

Abstract: In a three phase inverter which is composed of transistors turned on or off in accordance with the PWM control, the pulse widths of PWM gate signals for the transistors are determined in accordance with the magnitudes of two of the three phases of the current to be output by the inverter.The load of a processor for generating the gate signals can be reduced to the great extent, and in addition thereto, the waveform of the output current of the inverter is much improved.

Abstract: A DC voltage on an electric car stringing is supplied to a variable voltage and variable frequency PWM inverter so as to be converted into a three-phase alternating current which is supplied to a plurality of three-phase induction motors. The motors are connected to different wheels to drive an electric car. The inverter is controlled on the basis of an operating frequency command determined by adding or subtracting a slip frequency command to or from a motor speed and a voltage command proportional to the operating frequency command. On the other hand, a motor current command is set and compared with a maximum current value of currents of the plurality of motors, and the slip frequency command is corrected in accordance with a difference therebetween.