Otis Elevator Company

Kazuhiko Doi

Yasutami Kito

Masayuki Mori

Koji Yamada

The purpose of this invention is to provide secondary resistance low temperature compensation in vector speed control at values that are close to the actual secondary time constant even at startup of the motor wherein the secondary time constant operation is not carried out. The invention consists of vector speed control devices 1 to 5 of the induction motor IM, with secondary resistance low temperature compensation of the electric motor being carried out by installing a secondary time constant operator (6) which detects the secondary time constant of an electric motor; a comparator/register (7) which holds and outputs low temperature data .tau..sub.2 from a comparison of register data and the output .tau..sub.2 of the aforementioned operator (6); and a damping unit (8) which, during operation, carries out replacement of sequential data with the output .tau..sub.2 of the operator (6), and, during shutdown, which turns to the output values .tau..sub.2L of the comparator/register unit (7), is caused to hold the damping characteristics, and which outputs this data to a slip angular frequency operator (5) of the vector control circuit, and by output from the damping unit (8) a value that is close to the actual secondary time constant at the time of startup, and thereupon, output the sequential data .tau..sub.2 .

Temperature compensator circuit for an induction motor

This invention provides a vector control method for controlling an induction motor that is used to drive an elevator based on secondary time constants, wherein the secondary time constants, which have been corrected for temperature, are determined in a short amount of time and the precision of the determination is improved, by passing a constant current of the same phase as during a similar operation to the excitation side of the induction motor while the elevator is mechanically stopped and then determining the secondary time constants.

Vector control method of induction motor

In an elevator provided with an inverter driven induction motor, output torque is determined by direct current of an inverter, slip frequency is determined from the thusly determined torque, the gap between an open-loop dictated speed pattern and the actual speed is compensated by the slip calculated during acceleration and constant speed movement, so that the open-loop control may be improved in terms of stop position precision.

Speed control system for elevators

A star-connected sensing resistor at the A.C. output side of a PWM inverter detects an output voltage across the resistor, a PWM control according to the invention then amplifies the detected voltage, compares the amplified voltage with a sine wave voltage command signal, amplifies the compared output in a P-I amplifier having a definite gain for a D.C. current, compares the P-I amplified output to a carrier and thus provides a PWM output for controlling the inverter.

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Narita, Japan

Kazuhiko Doi