Abstract: A system for measurement of shaft angles wherein a synchro resolver (10) is sequentially pulsed, and alternately, a sine (32) and then a cosine (36) representative voltage output of it are sampled. Two like type, sine or cosine, succeeding outputs (V.sub.S1, V.sub.S2) are averaged and algebraically related to the opposite type output pulse (V.sub.c) occurring between the averaged pulses to provide a precise indication of the angle of a shaft (18) coupled to the resolver (10) at the instant of the occurrence of the intermediately occurring pulse (V.sub.c).

Abstract: A microprocessor-controlled antenna positioning system for automatically steering a rotatable antenna in the direction of a source of radiated signals is disclosed. The present invention, which is particularly adapted for use in a television receiver or a subscription television receiver (STV) decoder, automatically seeks the best signal when a new channel or frequency is selected, remembers that preferred antenna position, and will return to it whenever that channel or frequency is subsequently selected. A large number of desired antenna headings may be stored in memory for subsequent use and the computer-selected antenna heading may be modified to avoid TV ghosts or to select a second station on the same channel. The system determines optimum antenna direction by sweeping the antenna through a full 360.degree. circle, keeping track of the width of receivable signal lobes.

Abstract: A system for controlling the speed of a brushless DC motor includes a microprocessor for generating stator control drive signals responsive to Hall sensors detecting relative rotor-pole-stator positions. Hall sensor signal transistions are compared against a reference frequency to provide an error signal which is processed by the microprocessor in accordance with a transfer function to emulate a type II servo loop. Stator commutation control signals are reduced in duration proportional to the resulting processed error signal. The control signals are thereafter applied to integrating current drives energizing the stator coils with triangular current signals.

Abstract: In a commutating device for an electric motor which is supplied from a d-c voltage source, which includes semiconductor switching elements arranged in a bridge circuit and addressed by means of a control voltage in dependence on the rotor position of the motor, in order that the semiconductor switching elements can be addressed without transformers and without separate control voltage sources, the residual voltage dropping across the load circuit of the semiconductor switching elements and/or the inverse voltage stored in the respectively preceding cut-off phase is used as the control voltage.

Abstract: In a brushless DC motor having a magnet (i.e.--a field flux generating means) and multiphase coils, a current is distributed from a DC voltage source to the multiphase coils by selectively activating a plurality of output transistors according to a set of output signals of a position detector. A distributor selectively activates the output transistors according to the output signals of the position detector. A command signal generator generates a command signal, and a low-pass filter is connected between the command signal generator and the distributor. A voltage detector detects voltage drops across the output transistors during each activated period and changes its output signal corresponding to the detected voltage drops when at least one of the voltage drops across the output transistors is smaller than a predetermined voltage.

Abstract: A method for controlling a plurality of electronic switches employed to connect an alternating current voltage source with a motor. The method comprises the steps of generating a signal, directing the signal to each of a series of output lines in sequence, regularly repeating the directing step, conducting the signal from the output lines to the electronic switches to actuate the electronic switches, and continuously resynchronizing the directing of the signal with the voltage cycle of the voltage source.

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 self-starting DC motor includes first and second main windings and a rotor. A starting winding is angularly offset from the first and second main windings for aligning the rotor offset from the main windings to start the motor from a noncogged position. A timing device is employed to energize the angularly offset windings when the motor is first turned on. After a time sufficient for the rotor to come to rest in its starting position, the starting winding is deenergized. A position sensing device generates signals indicative of the position of the rotor. A switch is responsive to the position indicating signals and alternately energizes the first and second main windings to operate the motor.

Abstract: A method and device are provided for substantially reducing the effect of a low frequency varying torque resulting from a characteristic asymmetric switching of a magnetic flux-sensitive control member when the control member is used to sense the rotating position of a rotor in a brushless d.c. motor.

Abstract: An inverter circuit having a bridge circuit comprising a plurality of switching elements connected in the form of a bridge for converting, into alternating current, a DC voltage produced by a DC voltage generating unit and which is received through a first switching circuit. The inverter circuit includes a pair of diodes and a spike absorbing capacitor which constitute a series network wherein the diodes are connected so as to be forward biased with respect to the DC voltage and the spike absorbing capacitor is connected between the diodes. The series network is connected in parallel with the bridge circuit and is connected to the DC voltage generating unit through the first switching circuit. The spike absorbing capacitor is connected in parallel with a smoothing capacitor of the DC voltage generating unit.

Abstract: A disk drive control circuit designed to eliminate undesirable mechanical resonances that occassionally occur in the disk drive system as a result of a particular combination of seek commands. The control circuit uses an electrical model of the mechanical system in order to estimate or predict whether a particular seek command is likely to excite a mechanical resonance. The electrical model may be a filter network having frequency response characteristics similar to the mechanical system. The current used to drive a linear motor of the mechanical system is then applied to the filter network. The signal output from the filter network, which network effectively models the mechanical system, is thus representative of the mechanical response of the system upon performance of the seek operation. This signal output is monitored, and if it exceeds a predetermined threshold level, steps are taken to alter the system response so as to avoid exciting the mechanical resonance.

Abstract: The machine flux of a rotating-field machine is determined from the digitized values of the machine stator terminal voltages and conductor currents averaged within a sampling period of an associated digital evaluation system. In order to form each component of the machine flux, the average value of a stator terminal voltage of the same phase, reduced by the ohmic voltage drop in that phase of the stator winding of the rotating-field machine, is multiplied by the clock period of the digital evaluation system and by a scaling factor and the average values so formed for each clock cycle are summed up. From the integral so obtained, the digitized value of the conductor current of the same phase averaged within a sampling period of an associated digital evaluation system and appropriately scaled, is substracted. The simulation of the machine flux can thereby be accomplished digitally.

Abstract: A motor drive system which utilizes the relatively poor storage time or turn-off time of Darlington pair power transistors which have typically been used as the driver elements in inverter motor driver applications. It primarily finds use in multiphase systems, such as the six step three phase inverter. The relatively long turn-off time of the power Darlington provides relatively constant collector current to the motor without the need for additional circuitry to provide constant base drive load. An additional circuit automatically and dynamically tailors the motor torque to the load requirements to minimize unnecessary use of electrial energy.

Abstract: A motor control system for AC motors utilizing an inverter which is switched to provide pulsewidth modulated DC voltage to be applied to the motor in phase sequence. The pulsewidth modulation is a function of an input reference signal, a signal dependent on motor current and a boost signal operative at low speeds. The motor voltage is continuously regulated as a function of load to provide the necessary power to drive the load.

Abstract: A start-up control technique is disclosed for an AC motor. At least one H-switch connects a motor winding to a pair of AC-supplied power lines and is switched between designated states to yield a fundamental frequency component voltage waveform in the winding phase shifted from the voltage waveform in another winding. A rotating field is provided for start-up, without energy-storage phasing capacitors or inductors.

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 circuit is disclosed for controlling operation of a single phase electric motor to obtain maximum efficiency over a complete range of load conditions for the motor. Under conditions of less than full load, single phase motors waste electricity when full AC power is continuously supplied thereto. At less than full load, the torque requirements of a motor are reduced and therefore the flux can be reduced, thus increasing the efficiency. An electrical switch, in electrical series with the motor, is used to control the motor flux by reducing the "on time" of the switch and thereby decreasing the voltage applied to the motor. The ratio of auxiliary winding voltage to main winding voltage is the parameter used in the instant invention to provide a measure of the load condition of the motor and thus operate the electrical switch.

Abstract: A microcomputer for use with an induction motor drive system processes machine drive system currents, voltages and speed to compute real time machine efficiency. From real time machine efficiency determinations, the microcomputer determines the optimum combination of machine slip frequency and machine air gap flux. The magnitude and frequency of machine stator current are regulated, responsive to the difference in magnitude between optimum machine air gap flux and actual machine air gap flux, and the difference in magnitude between optimum slip frequency and actual slip frequency, respectively, to assure machine steady state operation at maximum efficiency irrespective of machine load conditions.

Abstract: A braking control circuit for an alternating current motor is disclosed as having a winding and adapted to be coupled to an energizing control circuit for connecting a source of AC voltage to and for disconnecting the source of AC voltage from the winding. The braking control circuit comprises a selectively controlled rectifier operative in a first conductive mode for applying rectified current to the winding to brake the motor and in a second non-conductive mode, and a switching circuit coupled to the rectifier and responsive to the disconnecting of the source of AC voltage from the winding for switching the rectifier between its first and second modes at a first switching rate to brake the motor rotation at a corresponding first braking rate, and thereafter for switching the rectifier between its first and second modes at a second switching rate different from the first switching rate to brake the motor at a corresponding second braking rate.

Abstract: A method for optimizing the power input to a plurality of parallel connected hysteresis motors wherein a three phase alternating voltage source jointly supplies the motors with an adjustable operating voltage. The method includes measuring, during the operation of each motor, the phase angle difference between motor voltage and motor current and determining the power factor therefrom for each motor. The effective current value of each motor is measured during operation and is combined with the power factor to obtain the active current for each motor. An active current limit value at which each motor transitions from synchronous to asynchronous operation is measured once and stored for each motor prior to commencement of continuous synchronous operation.