Adaptive induction motor controller
AssigneeImec
InventorsDonald E. Fulton, William P. Curtiss, Jonathan R. Leehey
Life of this patent
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Abstract
A method of measuring induction motor parameters so that the speed and torque control of an induction motor controller may be optimized. While the motor is stopped, a test signal made up of a current pulse of a known amplitude is applied to one or more windings of the motor stator for a selected period of time, after which the current pulse is turned off. After a short delay, the instanteous voltage across the stator windings is measured, and also an integration of the stator voltage is started which continues long enough so that the stator voltage decays to substantially zero. The measured voltage and integrated voltage are respectively proportional to the rotor resistance and the motor magnetizing inductance.
Claims22
Apparatus for measuring the inductance and rotor resistance of an induction motor, comprising:
- means for applying a signal across one or more stator windings of the motor to cause a DC current pulse of a substantially constant magnitude to flow through the one or more windings for a first interval of time;
- means for preventing current from flowing through said one or more windings after the end of the first interval;
- and
- means, responsive to the voltage across said one or more windings, for processing the voltage to determine the inductance and rotor resistance of the induction motor.
A method for measuring the inductance and rotor resistance of an induction motor comprising the steps of:
- applying a signal across one or more stator windings of the motor to cause a DC current pulse of a substantially constant magnitude to flow through said one or more stator windings for a first interval of time;
- preventing current from flowing through the one or more stator windings after the end of the first interval of time;
- providing a delay for a period of time after the first interval of time;
- measuring the amplitude of the voltage across the one or more stator windings after the delay to provide a value representative of the rotor resistance;
- and
- integrating the voltage over a second interval which begins after the delay and which extends until the voltage decays to substantially zero.
Circuitry for measuring the inductance and rotor resistance of a three-phase induction motor comprising:
- a flux-feed-forward motor controller, responsive during periodic intervals of operation to input signals representative of a particular dynamic response desired from the motor, for providing control signals representative of stator current magnitude and frequency which will produce the desired dynamic response;
- motor drive circuitry responsive to the control signals from the motor controller for causing stator currents of said magnitude and frequency to flow in the stator windings;
- means, operative between said intervals of operation, for driving a substantially rectangular current through two of said stator windings while preventing current from flowing in the third of said stator windings;
- means, operative between said intervals of operation, for measuring the voltage across said two stator windings at a first time occurring after the end of the current pulse, to provide a first output signal representative of the rotor resistance;
- and
- first integrating means, operative between said intervals of operation, for integrating the voltage across the two stator windings over an interval beginning at substatially the first time and ending after the voltage has reached substantially zero to provide a second output signal representative of the motor inductance.
Dependencies are inferred from the claim text.