Apparatus and method used with AC motors for controlling motor operation
AssigneeAllen-Bradley Company, Inc.
InventorsPeter B. Schmidt, Thomas Rehm
Life of this patent
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Abstract
A method and apparatus for motor control tuning wherein an extremely accurate estimate of inertia is determined by using the second derivative of a desired motor velocity and the torque supplied to a motor is altered as a function of inertia.
Claims22
A method to be used with a model reference adaptive motor controller where the motor controller receives a command velocity signal and produces the control torque signal that drives a motor at a motor velocity, said method estimates inertia and tunes the controller, the method comprising the steps of:
- (a) deriving a motor velocity signal that is indicative of motor velocity;
- (b) determining the difference between the motor velocity signal and the command velocity signal to produce an error signal;
- (c) determining the second derivative of the command velocity signal to produce a jerk signal;
- (d) mathematically combining the jerk signal and the error signal to produce a derivative signal;
- (e) integrating the derivative signal to produce an inertia estimate;
- and
- (f) using the inertia estimate to alter the control torque signal.
A method to be used with a model reference adaptive motor controller for regulating a control torque signal to a motor, the motor controller receives a command velocity signal and produces the control torque signal that drives the motor at a motor velocity, the controller includes a model that produces a model velocity signal indicative of an ideal motor velocity, the controller also includes a feedback loop, the method comprising the steps of:
- (a) determining a motor velocity signal indicative of the motor velocity;
- (b) determining the first derivative of the command velocity signal to produce an acceleration signal;
- (c) determining the second derivative of the command velocity signal to produce a jerk signal;
- (d) determining the difference between the motor velocity signal and the model velocity signal to produce an error signal;
- (e) mathematically combining the jerk signal and the error signal to produce a derivative signal;
- (f) integrating the derivative signal to produce an inertia estimate;
- (g) mathematically merging the acceleration signal and the inertia estimate to produce a feedforward torque signal;
- and
- (h) adding the feedforward signal to a feedback signal to produce the control torque signal.
A method to be used with a model reference adaptive motor controller for regulating a control torque signal to a motor, the motor controller receives a command velocity signal and produces the control torque signal that drives the motor at a motor velocity, the controller includes a feedback loop, the method comprising the steps of:
- (a) deriving a motor signal that is indicative of motor velocity;
- (b) determining the difference between the motor signal and the command velocity signal to produce an error signal;
- (c) determining the first derivative of the command velocity signal to produce an acceleration signal;
- (d) determining the second derivative of the command velocity signal to produce a jerk signal;
- (e) mathematically combining the jerk signal and the error signal to produce a derivative signal;
- (f) integrating the derivative signal to produce an inertia estimate;
- (g) mathematically merging the acceleration signal and the inertia estimate to produce a feedforward torque signal;
- and
- (h) adding the feedforward signal to a feedback signal to produce the control torque signal.
An apparatus to be used with a model reference adaptive motor controller for regulating a control torque signal to a motor, the motor controller receives a command velocity signal and produces the control torque signal that drives the motor at a motor velocity, the controller includes a model that produces a model velocity signal indicative of an ideal motor velocity, the apparatus comprising:
- (a) a sensor to determine an actual motor velocity signal;
- (b) a difference calculator that produces an error signal by determining the deviation between a motor velocity signal and a model velocity signal;
- (c) a derivation module that receives the command velocity signal and determines the second derivative of the command velocity signal thus producing a jerk signal;
- (d) a multiplier to multiply the jerk signal, the error signal, and a gain to produce a derivative signal;
- (e) an integrator that receives and integrates the derivative signal thus producing an inertia estimate;
- and
- (f) a compensator that uses the inertia estimate to derive the motor torque signal.
Dependencies are inferred from the claim text.