Abstract: A polyphase induction motor propels an elevator car. The motor is powered by a multiphase inverter which receives power from a battery. The inverter is controlled in such a way as to control the frequency and amplitude of the power supplied to the motor in order to control the motor's speed, acceleration, and slip. That inverter control is accomplished by sensing the motor's speed and in response providing predetermined slip and torque signals. The slip can be controlled over a range which can provide negative slip, by which power is regenerated into the battery, which is thereby charged, and positive slip for motoring torque. A charger also charges the battery. The motor and its controls are thereby ostensibly isolated from the power system that supplies power to the charger, the battery handling the peak power requirements. Thus, little noise is injected into the power system. This motor control system is thus efficient to operate, economical to build and very quiet.

Abstract: A circuit for duplicating the function of an incremental shaft encoder comprises a rugged resolver connected to a hybrid digital-analog circuit which generates output signals identical to those of a counterpart incremental encoder. The digital portion of the circuit includes terminals whereat absolute angle measurements of a shaft may be made.

Abstract: A dual speed resolver to digital conversion system with coarse and fine interlocking. The reference frequency is utilized to drive a bang-bang servo loop under priority control of the coarse mathetics when it is necessary to pass control to the coarse loop.

Abstract: The power switch driver circuit of a brushless DC motor control ensures synchronous operation by utilizing a ROM addressed by motor shaft position sensors. Excess current drawn by the motor windings is sensed by a detector which provides an additional bit of address input to correct the condition. The address input may also be modified by a bit signifying forward or reverse operation of the motor.

Abstract: In order to provide high accuracy shaft angle to linear DC voltage conversion using low accuracy devices, a linear synchro is excited by a 2.5 KHZ square wave which is power buffered, the square wave also used to synchronously demodulate the output of the wound component by sampling and a demodulated voltage then filtered and scaled to the required levels using commonly available operational amplifiers.