Abstract: To determine the flux in the air gap of an electrical machine having distributed stator windings, the voltages across two coils of a phase belt in certain phases of the stator are measured and the voltage across one coil in each phase belt is subtracted from the voltage in the other coil. The voltage differences are integrated to provide a measure of the air gap flux. Measurement of the entire air gap flux about the machine can be obtained utilizing two coils in a phase belt per phase of the machine. The instantaneous electromagnetic torque in the machine can be calculated directly as a function of the calculated air gap flux and of the currents in the stator windings. Such flux and torque measurements are obtained utilizing electrical connections to the existing coils of the machine, without the need to modify the machine by adding further windings or sensors. The flux and torque signals so obtained may be utilized in motor controllers, and are particularly useful for control of AC induction motors.

Abstract: An energy-saving system for feeding an electric induction motor serving as a load, and which is operated from a 3-phase voltage power line, and in conjunction with feeding conductors for the motor includes a power-delivery sub-system operating in a magnetically linear region and coupled to the 3-phase voltage power line for providing variable feeding voltages to the induction motor, a sensing device coupled to the induction motor for generating a signal indicative of the derivatives of active power consumed by the induction motor with respect to the voltage of at least one phase provided to the induction motor, and a control apparatus coupled to the sensing device and to the power-delivery sub-system for regulating at least one of the feeding voltages, so that the derivative of the active power with respect to the voltage of that at least one phase is always substantially zero; thus for a given mechanical power output the power consumption of the induction motor is optimized, while concurrently losses in the

Abstract: A control for a wound rotor induction motor including shorting switches in a secondary resistance network comprises an input comparator with voltage limiting switched by the rotor voltage, a pulse generator responsive to the input comparator to generate voltage pulses of predetermined constant duration at a frequency proportional to the frequency of the rectangular voltage wave, a low pass filter effective to filter the output of the pulse generator to a DC voltage inversely related to rotor speed, a DC power supply effective to generate a plurality of DC reference voltages, a plurality of switch control comparators, each receiving the output of the low pass filter on one input and one of the DC reference voltages on the other input and a plurality of switch actuators, each switch actuator being responsive to the output of one of the switch control comparators to activate a group of shorting switches at a predetermined rotor speed during motor acceleration and deceleration.

Abstract: A motor starting control circuit is provided with an auxiliary switch (100), including a triac (102) and series resistor (114), connected across the start capacitor (5) for quickly discharging the start capacitor (5) upon disconnection of the start capacitor (5) from the AC source (4). This enables a lower rated start switch (6) by eliminating extra voltage thereacross caused by an otherwise charged start capacitor (5).

Abstract: A motor control apparatus including an arithmetic circuit (113) for calculating a current command, a holding circuit (118) for holding the current command, a pulse-width modulating circuit (114) for pulse-width modulating an output signal from the holding circuit (118) and provided with a dead zone with respect to the output signal, and a transistorized amplifier/converter circuit (117) for controlling a motor by the pulse-width modulated signal. The arithmetic circuit (113) adds a compensating signal, to the current command to compensate for motor control losses due to the dead zone, and delivers the result to the holding circuit (118).

Abstract: A variable frequency adjustable speed motor drive allows restart of a spinning induction motor by initially increasing the frequency of the associated inverter while keeping the DC voltage source thereof low, then by decreasing the frequency of the inverter while monitoring the effective motor impedance V.sub.DC /I.sub.DC or V.sub.AC /I.sub.AC until the latter jumps at an initial level indicating matching of the frequency with the motor spinning speed. Thereafter, the DC voltage is restored in magnitude and the inverter is increased in frequency to match the desired motor speed.

Abstract: In an elevator driven by an induction motor and having a slip control device for generating a slip frequency command signal on the basis of an error between a speed command value and a running speed value of the induction motor so as to control a VVVF type inverter which in turn provides a corresponding alternating current of variable voltage and frequency, the inverter having a smoothing capacitor on a D-C side thereof, a control apparatus for stabilizing torque of the induction motor by smoothly changing operation of the induction motor from a powering mode to a regenerative mode, the control apparatus comprising a current detector for detecting charging current of the smoothing capacitor having a portion for detecting polarity of the slip frequency command signal and a unit responsive to the charging current detected by the current detector and the slip frequency command signal generated by the slip control device for changing operation of the induction motor from the powering mode to the regenerative mode

Abstract: To a controller utilizing thyristors have been added delayed resetting circuits connected to timing circuits for enabling delayed firing, and also circuits for inverting polarity of error signal in order to accommodate regenerative and reverse-plug braking. Other additional circuits include circuits for controlling a ramp generator for developing different segments of a ramp required for different modes of operation of a motor. Sequence switching circuits in the circuits controlling operation of the motor determine that full acceleration or deceleration of a selected mode is completed before a newly selected mode is started.

Abstract: An induction motor drive control system is controlled according to a torque demand and a rotor flux amplitude demand while using only a shaft position feedback and providing an open loop equivalent of a vector voltage control approach to the control of the induction motor.

Abstract: A regulator for a closed loop control system receives a sinusoidal reference input signal i* and sums it with a feedback signal i to produce an error signal. A control signal is produced by the regulator by combining signal components which include: (a) a component proportional to the error signal; (b) a componet proportional to the integral of the error signal; and (c) a component related to the frequency of the reference input signal. The latter component insures that an accurate control signal is produced by the regulator over a wide frequency range.

Abstract: A motor drive circuit controlling the period of each cycle of line voltage which is supplied through an electronic switch to a motor winding. The phase difference between the current through and the voltage across the winding is measured and compared to a reference. The duration of the period of a cycle when the switch is closed and supplies power to the motor winding is varied in relation to the phase comparison so as to maintain an optimal phase angle or power factor for the motor. To eliminate misfiring of the switches in a single phase unit, an a.c. coupled power supply is used to power the control circuits and a varistor is located across the line. Also, fuses are used to protect the circuitry. In a three phase circuit, resistive dividers in current and voltage sensing circuits are matched within 1% of each other to provide proper triggering of the switches of each phase with respect to each other.

Abstract: An electronic sensing and triggering circuit including an integrated overvoltage protection circuit is used in conjunction with an energy storage capacitor as well as output transistors for providing a vigorous voltage pulse supplied through a current pulse transformer to the gate of an SCR in a brushless excitation circuit discharge circuit branch.

Abstract: When a synchronous motor (6) using a permanent magnetic field is controlled by the control of an inverter (4) receiving a pulse width modulation signal, wherein the reactive component of an armature winding current is defined as I.sub.b, the inductance of the armature winding as L, the counter electromotive force constant of the synchronous motor as K.sub.1, and the constant introduced from the pole number of the synchronous motor as K.sub.2, the value of the reactive component I.sub.b of the armature winding current is limited so that the multiplied product of K.sub.2, L, and I.sub.b does not exceed the value of K.sub.1.

Abstract: A method and apparatus for controlling a permanent magnet synchronous motor (M), wherein an inverter (4) is controlled in response to PWM signals (PA-PF) obtained by comparing a reference carrier wave (VA) with signals representing differences between armature winding current command signals (RTC, STC, TTC) of the respective phases and detected armature currents (IR, IS, IT).The degree of saturation of the difference signals defined in association with a peak value of the reference carrier wave (VA) is detected. The phases of the current command signals (RTC, STC, TTC) are changed from those which provide an orthogonal relation between a resultant armature current and a main flux of a magnetic field.

Abstract: A centrifuge overspeed protection and imbalance detection system is structured to provide a method for detecting rotor imbalance and rotor overspeed. The system has a single transducer to provide real-time data necessary to detect rotor imbalance and control motor speed.Motor speed is controlled by synthesis of a drive frequency signal for driving the inverter motor control. The drive frequency signal may be inhibited to provide slow acceleration or deceleration, or to shut the motor off by providing a zero slip frequency. Motor control is responsive to a Rotor Identification circuit and operator programming, as well as a closed loop response to the real time tach signal.Imbalance detection is provided by counting tach pulses in each of a plurality of intervals, detecting deviations in tach pulse rate and sounding an alarm when the irregularity of tach pulse signals exceeds the limits of a predetermined standard deviation.

Abstract: A drivetrain (48) for an electric passenger vehicle (10) includes a battery (40) for energizing a single-phase A.C. traction motor (18) which drives a ground engaging wheel (12) through a multispeed transaxle (20). The motor is characterized by an external ferrite permanent magnet rotor (26) drivingly engaging an input shaft (32) of the transaxle. The motor is controlled by an inverter circuit (44) and a control circuit (46) which generates switch command signals to reciprocally actuate power transistors (56) and (62) within the inverter circuit as a function of operator demand, rotor position and rotor speed. The control circuit includes a motor positioning circuit (442) which toggles the motor current when the rotor speed falls below a predetermined level to dither the rotor about a park position for a predetermined period. A prestart rotor positioner (224) is provided to mechanically lock the rotor in its park position to ensure the availability of a high electrical starting torque.

Abstract: A method for developing current control signals from motor terminal voltage in the control of alternating current electric motors which utilize electric current control signals oriented to the phase of a flux component in a rotating field for applying current so as to control the flux and torque in the motor. The method includes developing flux signals from measurement of motor terminal voltage and integrating those signals to develop corresponding flux signals. In one form, the method eliminates DC components occuring in the resultant flux signals by locating local maxima and minima of the resultant flux signal and correcting the value of the flux integrator so as to provide maxima and minima flux signals having equal absolute values. The method also includes establishing an initial flux in the motor prior to startup which is oriented in a predetermined manner such that initial current applied to the motor can be applied so as to immediately develop torque, if required.

Abstract: An AC induction motor brake control apparatus and method are provided for energizing the motor with an inverter supplied first voltage and an additional brake circuit supplied second voltage in phase with and additive to the first voltage as required to determine a desired brake torque above base speed operation.

Abstract: Apparatus and method for reducing the voltage drop in an electrical power distribution system during the starting of a multi-phase induction motor having stator windings supplied therefrom and for decreasing the loss in starting torque of the motor. A capacitor is provided for direct connection across each stator phase winding of the motor. These are electrically connected to the stator windings substantially simultaneously with the motor being supplied with power from the distribution system. These capacitors have a capacitance which exceeds that required to raise the no-load power factor of the motor to unity at running speed but is less than that which will correct the power factor of the motor to unity under locked rotor conditions. Preferably these capacitors are electrolytic-type capacitors and have a capacitance which will reduce the motor starting current by at least approximately 30%.

Abstract: A constant voltage voltage-source inverter of a motor drive includes in its DC-link the combination of diode means, a GTO device and an auxiliary thyristor, the GTO device and the auxiliary thyristor upon transferring to the regenerating mode being cyclically controlled for conduction concurrently with the thyristor of the AC/DC converter so as to match the (voltage-current) domains converter and input of the inverter. Conduction of the GTO device is interrupted before each cyclical control thereof to allow recovery.Initiation of GTO and auxiliary thyristor conduction upon mode transfer is retarded to allow settling of the system before firing the thyristors of the AC/DC converter with a different firing angle.