Abstract: A method and circuit for application in a PMW inverter for controlling power to an AC motor in which a hysteresis modulator is employed as a current limiter to override sine-triangle modulation in a PWM generator circuit. When the magnitude of motor current reaches a hysteresis band upper limit, the hysteresis modulator generates a large limit current to a summing input on a current regulator which feeds the PWM generator to override and mask out the normal sine-triangle modulated signal. When the magnitude of motor current decreases to a hysteresis band lower limit, the limit current is terminated, and the sine-triangle modulation is resumed.

Abstract: To reduce harmonics in an induction machine (33) which is fed by a self-commutated inverter (30), the trajectory of the flux vector of the induction machine is conducted along an edge path having at least 2.sup.p .multidot.q.multidot.m edges, where p is an integral number .gtoreq.1, q.gtoreq.2 is the number of voltage stages of the inverter and m.gtoreq.2 is the number of phases of the induction machine. In this arrangement, the flux vector is alternatingly conducted along straight and zig-zag segments. This reduction is essentially achieved by means of at least one second flux conducting circuit having a second coordinate con=verter (56) and a second comparator (57) in addition to a first flux conducting circuit having a first coordinate converter (54) and first comparator (46), the flux components (.psi..sub..beta.1' -.psi..sub..beta.3') at the output of the second coordinate converter being shifted by 30.degree. in phase with respect to the flux components (.psi..sub..beta.1 -.psi..sub..beta.

Abstract: For connecting the d-c terminals of a voltage-source inverter to a direct current (d-c) power source, a d-c link capacitor is connected directly between the d-c terminals, a line capacitor is connected in parallel with the d-c link capacitor, and a series inductor is connected between the line capacitor and the source. A dynamic brake resistor and an electric power chopper are connected in series with one another across the line capacitor. Between the two capacitors, no inductance is provided but a resistor is inserted in the braking current path during electrical braking operation of the inverter.

Abstract: An apparatus for controlling an adjustable-speed alternating current motor coupled to drive an elevator cage. The apparatus includes a converter connected to a source of AC power for converting the AC power into DC power, an inverter connected through relatively positive and negative conductors to the converter for inverting the DC power into DC output power having adjustable frequency, voltage magnitude, and current magnitude to drive the motor, and a control circuit for controlling an inverter to drive the motor at an adjustable speed. When a power failure occurs, the control circuit prevents flow of power through the converter to the power source and reduces the current magnitude of the inverter output power to a predetermined minimum limit enough to maintain a synchronous relationship between the inverter and the motor.

Abstract: A power converter for starting an AC induction motor includes a frequency detector which compares the frequency of an AC output of the converter with a predetermined frequency and generates a detection signal if the AC output frequency is lower than the predetermined frequency, a current controller which controls the power converter such that an AC output current supplied to the motor is determined in accordance with a given current reference if the detection signal is generated, and a voltage controller which controls the power converter so that an AC output voltage applied to the motor is regulated in accordance with a given voltage reference if the detection signal disappears.

Abstract: To regulate the speed of a plurality of asynchronous motors fed by a converter having a variable output frequency and output voltage and having a load-dependent slip, particularly asynchronous motors for driving spindles of a textile machine, the rotational frequency of several selected asynchronous motors is measured by means of respective digital frequency indicators. This measurement takes place in continuous repetition, always beginning simultaneously. The pulses of the frequency indicators are counted by means of respective first counters (1-6), all of which release a pulse when they reach the same counter condition. An OR circuit (13-17) connects the counter outputs with a second pulse counter (18) in such a manner that this condition is reached first by the output pulse released by the highest rotational frequency and then by the output pulses released by the second-highest rotational frequency, etc.

Abstract: An object sensing apparatus includes a plurality of light emitting diodes for illuminating a region of space and a plurality of closely arranged light detectors for receiving light reflected from an object. The apparatus is particularly useful in connection with automatically operated doors.

Abstract: A drive arrangement is described, comprising a multi-phase synchronous motor whose phase windings are energized with energizing currents whose strengths are periodic functions (f1, f2, f3) of a rotor-position or translator-position measurement value (p) which is determined by means of an incremental detection system. The drive arrangement has means for adjusting the initial position-measurement value (p) before the motor is energized with the periodic energizing currents. For determining the initial value, the phase windings are energized in different consecutive time intervals (T) with measurement alternating currents (im1, im2, im3) whose amplitudes are equal to K times the function values (f1, (ROPOS), f2(ROPOS), f3(ROPOS)) of the periodic functions (f1, f2, f3) associated with different auxiliary values (ROPOS). The frequency and amplitudes are selected in such a way that the rotor or translator performs a vibration whose vibration amplitude corresponds to only a few electrical degrees.

Abstract: A reduced voltage starter for gradually starting a polyphase motor having an acceleration control circuit for gradually applying power to the motor and detector circuits for detecting various fault conditions for terminating power to the motor. A shorted solid state switch detector senses when one of the semiconductor switches applying power to the motor is shorted to terminate the application of power from the remaining phases. A phase angle control circuit insures a uniform application of power to the motor. A phase rotation detection circuit detects when the three phases are in other than their correct sequence and terminates power in the event of such detection. An underload detection circuit senses when the current drops beneath a preselected reference after the motor has reached its full speed and terminates power in response to such detection. A line-to-line-to-line-to-neutral convertor produces signals representative of the line-to-neutral voltages which are necessary for other circuit functions.

Abstract: An inductio motor torque/flux control system the motor flux is forced down while accelerating and force up while decelerating to maintain a required flux level at all speeds. This is achieved through vectory control by generating a direct current component in relation to the flux demand while imposing limits thereto corresponding to the maximum desirable resultant current vector, and by generating a quadrature current component which is held between limits defined by the sum of the squres of the two current components. The three-phase currents of the motor generated by vector control transformation are used to control a voltage-source inverter in a bang-bang fashion. The conventional bang-bang technique is improved by tying up one pole while controlling in the bang-bang mode the two other poles. To this effect the motor back emf is detected when the poles are simultaneously tied to one of the DC link terminals, and the tied-up pole is selected by the emf so detected.

Abstract: In an induction motor controller, for the amount equivalent to the secondary interlinkage flux computed by use of a component of lag of first order based on the search coil voltage or the primary voltage of the induction motor, an error with respect to the actual secondary interlinkage flux is increased in a low-speed range. However, since an estimated amount equivalent to the secondary interlinkage flux computed based on the estimated amount of the secondary interlinkage flux is also attended with the same error with respect to the secondary interlinkage flux, when the former is substracted from the latter, there only remains a term concerning the speed estimation error, which enables an estimation of the speed to be conducted also in the low-speed range.

Abstract: A method and apparatus for determining the flux vector of a rotating-field machine that enables a rotating-field machine, especially a permanently excited synchronous machine, to be controlled without mechanical transmitter even at low frequencies. An EMF vector is interated in a flux computer to determine a direction angle of a model flux vector. The flux vector rotates a perpendicular correction vector until an oscillating stator current component parallel to the model flux vector generates no corresponding oscillations in the stator current component perpendicular thereto. Preferably, a multiplier forms a correlation signal between the impressed oscillating stator current component and the oscillations in the stator current component perpendicular thereto. The correlation signal indicates the value of the components of the correction vector perpendicular to the model flux vector.

Abstract: A pulse width modulated control signal for use in motor control and with power supplies is generated by a dual-mode controller having variable frequency control in a discontinuous current operating mode. The controller also provides control in a continuous current operating mode, and makes a smooth transition therebetween.

Abstract: A method and apparatus is shown to control both the motor terminal current to vary in exact proportion as the motor shaft torque varies for any given excitation frequency. This obviates the need for ancillary motor speed control and prevents voltage boosting at low speeds from resulting in excessive motor losses for no load conditions. A motor is powered from an inverter, the inverter providing an output voltage with independent control of amplitude and frequency. A frequency signal is fed directly to the inverter from a frequency input, the frequency input also being connected to a multiplier. The multiplier provides the amplitude signal for the inverter based on the product of the input frequency and motor current.

Abstract: A blower motor control for an air conditioner is carried out so that when a detected actual rotation speed has come into an allowable deviation range to a target rotation speed at the time of controlling the motor so as to approach its rotation speed to the target rotation speed, the output for adjusting the rotation speed is not changed. As a result, a stable rotation speed can be obtained as long as the load on the motor does not fluctuate. Furthermore, after the output has been fixed, the allowable deviation range is expanded to prevent the output from changing even if slight load fluctuation is caused. This allows stable controls.

Abstract: In speed control apparatus and method for a motor operable to drive a load whose magnitude varies over a predetermined period which use a unit for controlling voltage or current supplied to the motor such that the speed of the motor can coincide with a command speed, n pieces of data indicative of voltages or currents supplied to the motor and corresponding to n divisions of the predetermined period are independently stored in a read/write storage, at least one of the n pieces of data is corrected at the rate of each of the n divisions in accordance with a difference between the command speed and the speed of the motor, and the voltage or current supplied to the motor is controlled in accordance with at least the one of the n pieces of data, so that pulsation and noise occurring especially under low revolutions can be minimized.

Abstract: A motor having a capacitor in series with its coil permits the motor to operate at a higher voltage or range of voltages over its design voltage. A method determines the correct value of a capacitor to change the design voltage of a motor to a different operating voltage. A receptacle can be used to receive capacitors of different values to vary the operating voltage of a motor. The receptacle is provided with a capacitor holding device which is marked with the operating voltage set by the capacitor. A timer clock has a motor of a design voltage which can be changed to a plurality of operating voltages. The timer clock can have the receptacle accessible from the exterior with a cover having the operating voltage marked thereon.

Abstract: An overcurrent protection system for AC motor control systems which provides a separate overcurrent shut down mechanism for each phase of the AC power used in an AC motor. These separate phase shutdown mechanisms provide protection for minor overcurrent conditions without shutting down the entire motor control system. The overcurrent protection system also provides a mechanical feedback apparatus for totally shutting down the motor control system only in a severe overcurrent condition.

Abstract: A system for controlling a polyphase electric motor, particularly at low speeds, using a load commutated inverter includes the generation of half sine wave signals within a range of desired frequencies which are subsequently converted to single phase alternating current power for application to selected windings of the motor. In a single channel polyphase embodiment, motor starting is achieved using zero current commutation and normal phase control. A two channel embodiment results in what amounts to two phase operation of the motor.

Abstract: A current source inverter for a load commutated induction motor drive is controlled in relation to the direct and quadrature components of the current vector as assigned in response to stator voltage, speed reference and actual speed. Control is on the inverter and the converter in relation to both components.