Abstract: A tachometer is coupled to the rotor of an A.C. motor and generates an output voltage proportional to the rotor's speed. A VELOCITY COMMAND voltage is generated having an amplitude which specifies a desired rotor speed. The tachometer voltage is subtracted from the VELOCITY COMMAND voltage to produce a VELOCITY ERROR voltage. The output of a D.C. power source is chopped at a fixed frequency and variable pulse width, the pulse width being proportional at any time to the amplitude of the VELOCITY ERROR voltage. The chopped D.C. voltage is filtered to provide a variable D.C. voltage having an amplitude which is proportional to the amplitude of the VELOCITY ERROR voltage. The variable D.C. voltage is applied to an inverter which changes it into an A.C. voltage. The A.C. voltage is applied to the stator windings of the motor to drive the rotor thereof. The frequency of the A.C. voltage is variable and is proportional, at rotor speeds above 150 RPM, to the amplitude of the velocity command voltage.

Abstract: For the purpose of controlling the torque of a three phase induction motor a control system suitable to be operated by a computer is provided. A torque instruction, an angle of rotation, a flux angle, the magnitude of rotating magnetic field and suitable constants are used to produce current instructions for respective phases to pass stator current necessary to produce an instructed torque.

Abstract: A power control circuit for an induction motor wherein a servo loop is used to control power input by controlling the power factor of motor operation, and wherein the power factor is measured by summing the voltage and current derived square wave signals.

Abstract: In a control device of an AC motor wherein a torque equivalent to that of a DC motor is created by controlling the instantaneous values of its stator current, or in a vector control device, signals from a position detector such as a resolver coupled to the AC motor are utilized to form stator current instruction signals and to provide rotation position feed-back signals and rotation speed feed-back signals for the AC motor, thereby to perform precise servo-control.

Abstract: A method of, and apparatus for, monitoring the run-up to speed of asynchronous motors which are turned-off within a permissible blocking or cutoff time of the motor when the speed run-up is improper, wherein after turning-on the motor there is determined a first value of an electrical magnitude which is dependent upon the phase angle between the motor current and the motor voltage after expiration of a first time-delay following turning-on of the motor, and there is then determined a second value of said electrical magnitude after expiration of a second time-delay following the turning-on of the motor. Both the first and second values are compared with one another, and the motor is turned-off when, following such comparison, there is present a magnitude indicative of improper run-up to speed of the motor.

Abstract: A control system for an a.c. motor having a polyphase primary winding (stator winding) and a corresponding polyphase secondary winding. The primary and the secondary windings are supplied with current from different frequency converters provided separately for each of the windings. The alternating currents flowing through the primary and the secondary windings are in opposite phase with each other. A position detector is provided for detecting the position of rotor of the a.c. motor. The magnitude of the primary current is controlled proportionally to a current reference signal in dependence on deviation of a speed feed-back signal from a speed reference signal, while the magnitude of the secondary current is controlled to a constant value. The phases of the primary and the secondary currents are controlled on the basis of the rotor position.