Abstract: A simple combinational technique is disclosed using one or more H-switches for start-up control and frequency conversion in an AC motor. A coordinating logic system provides H-switch toggling timing patterns yielding phase shifted voltage waveforms in the motor windings to afford a rotating field during start-up, and provides irregular switching times yielding a chopped sinusoid output waveform of converted frequency for variable speed operation.

Abstract: A brushless D.C. motor which can provide a speed detection signal or position detection signal continuously even when the speed of rotation of the rotor is reduced includes a ring-shaped driving magnet magnetized to develop N and S poles alternatively; a rotary yoke having a plurality of flanges extending from the outer peripheral edge thereof toward a stationary yoke substantially to the middle of the outer peripheral end surface of the driving magnet in such a manner as to embrace the driving magnet, the flanges extending over two adjacent magnetic poles of different polarities at the boundary between these magnetic poles; and a magnetic-electric transducer element disposed at a position spaced from and opposing to the path of rotation of the flange surfaces adjacent to the stationary yoke and spaced from and opposing to the path of rotation of the outer peripheral end surface of the driving magnet.

Abstract: An optimum acceleration deceleration circuit for stepper motors wherein an error signal is fed to a rate limiter circuit which generates a speed output voltage. The speed output voltage is fed back to the rate limiter circuit through a non-linear gain amplifier and summing amps.

Abstract: An improved electromagnetic relay having a wafer of material with positive temperature coefficient of resistivity (PTC) mounted inside the relay combines a sturdy construction with low manufacturing costs adapting the relay for use as a starting relay for electric motors of compressors. For this purpose, the magnetic members of the relay are incorporated in the electrical relay circuit and are provided with attachments for plug-on connections of the relay to circuit pins of motor-compressor units.

Abstract: Disclosed is an instant reverse control circuit for a single phase, squirrel cage induction motor that has an exemplary use for opening and closing elevator doors. The motor has a running winding and a motor starting circuit comprised of serially connected start winding, capacitor, and centrifugal switch for deenergizing the start winding when the motor is up to running speed. The control circuit includes a relay operated, power reversing switch that supplies power to the starting circuit through an additional relay operated instant reverse switch. The instant reverse relay that operates the switch is connected in parallel with the starting circuit and its switch has a relay maintaining contact and a bypass contact. The bypass contact supplies reverse power to the start winding when the motor is to be reversed suddenly, such as to open a closing door that has struck an obstruction.

Abstract: A scalar control supplemented by a decoupler transfer function control is provided to develop frequency and voltage commands for a voltage controlled inverter driving an induction machine. The machine torque is controlled by the slip and corresponding torque producing component of stator current. The rotor flux is maintained constant by the flux component of stator current. The total stator current is controlled in the outer loop to hold rotor flux constant with desired torque during steady state conditions and the decoupler compensator varies stator voltage to maintain rotor flux constant during transient conditions.

Abstract: A DC motor control circuit for controlling the speed and direction of rotation including a plurality of linear amplifiers which are, respectively, connected to each of the stator windings of the DC motor and a pulse generator for generating rotational pulse trains which represent the rotational phases of the rotor of the DC motor and output impedance control pulse generator for generating based on the rotational pulse train control pulses which selectively control the linear amplifiers so as to produce nearly infinite output impedance and a motor control voltage and signal inverter for inverting the motor control voltage and a plurality of switching circuits connected to the inputs of the linear amplifiers for supplying the motor control voltage and phase inverter motor control voltage in a selective manner to each of the linear amplifiers and switching circuit control pulse generator for generating switching pulses based on the rotational pulse trains which are supplied to each of the switching circuits.

Abstract: An induction motor circuit which effectively prevents voltage spikes caused by leakage inductance of the induction motor stator windings without otherwise interfering with the overall operation of the induction motor. The circuit incorporates two windings between a common point and the positive supply and two other windings between the common point and the negative supply. Voltage spikes are suppressed by diodes connecting directly from the ends of each of the windings to the supply terminals oriented to the opposite end of the respective windings.

Abstract: In a current-fed static controlled synchronous motor drive which includes a ramp logic for establishing the desired firing retardation for the naturally commutated thyristors, an optical encoder provides a position signal and a velocity signal, while the ramp counting the velocity pulses is automatically aligned with the position signal by means of a phase detector causing either to add pulses from a local oscillator or to inhibit velocity pulses so as to compensate for a phase error in either direction. Alignment is also provided within 60.degree. initially by presetting the ramp counting in relation to a digital representation of sine 60.degree. time intervals over a fundamental cycle.

Abstract: A dynamoelectric machine has only a pair of line terminals adapted for selective connection across a single phase power source and is operable to be started in a split-phase mode, to run at a predetermined low speed in a single phase mode, and to run at a predetermined high speed generally in a two phase mode.

Abstract: A pair of anti-parallel connected NPN transistors function in push-pull manner to regulate alternately current power applied via the transistors to an induction motor driving a fan providing a generally constant motor load. As the transistors apply more or less current to the motor by varying the amount of line voltage applied thereto, the motor speed varies due to more or less pole slippage. The transistors, while reducing the voltage applied to the motor, generally maintain the sine wave characteristics of the applied voltage to preclude high current spikes and other undesirable transients that could result in conventional motor speed circuits utilizing thyristors that are phase-triggered to vary the half-cycle portions of the applied motor voltage.