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US 4,484,126 AGranted
Induction motor controller
AssigneeImec
InventorsDonald E. Fulton, Robert H. Comstock
Life of this patent
Estimating the term…
Abstract
The present invention generates a motor slip frequency value and two current magnitude values representing quadrature components of the motor stator current to be generated. Closed-loop control of the motor operation is provided by feeding back a signal representative of the motor shaft speed or position calculate the torque required from the motor. The feedback signal is separated into high and low frequency components. Additional circuitry changes the value in response to detected variations in the high frequency components of the feedback signal. The addition of this circuitry causes the motor control circuit to no longer represent the inverse of the motor transfer function network.
Claims17
An induction motor controller for providing closed-loop control of an induction motor, comprising:
- drive means for generating an A.C. stator current in each stator winding of the motor in response to first and second inputs applied thereto representative of the amplitudes of quadrature components of the A.C. stator current;
- means for monitoring the velocity of the motor rotor and for providing a velocity signal representative thereof;
- means responsive to the velocity signal and to a first signal applied thereto representative of desired motor rotor velocity for producing an error signal representative of the difference therebetween;
- network means, having a transfer function which is substantially the inverse of the motor transfer function and responsive to first and second inputs respectively representative of motor torque and motor flux level, for producing first and second output signals representative of quadrature components of motor stator current and for producing a slip frequency signal representative of the difference between the motor rotor angular velocity and the frequency of the motor stator current;
- wherein the drive means further includes means responsive to the slip frequency signal and to the velocity signal for providing a stator current frequency signal representative of the frequency of the stator current in the stator windings;
- means for applying the error signal to the network means first input;
- means for applying a signal representative of a desired flux level to the network means second input;
- and
- means for combining the network means first output signal and the velocity signal to provide a combined signal and for applying said combined signal to one of the drive means inputs, including:
- means for separating the velocity signal into high frequency components and low frequency components;
- means for adding said separated high frequency components and the network means first output signal to provide the combined signal;
- and
- means for applying the combined signal to the drive means first input;
- means for applying said second network means output signal to the drive means second input.
11 more elements
An induction motor controller, comprising:
- drive means for causing an A.C. stator current to flow in each stator winding of the motor in response to first and second inputs thereto representative of the magnitudes of quadrature components of the stator current;
- transducer means, responsive to movement of the motor rotor, for producing a feedback signal representative of the motor position;
- means for separating the feedback signal into low frequency components and high frequency components;
- detection means, responsive to an input command signal representative of a desired motor rotor position and to the feedback signal low frequency components, for providing an error signal representative of the difference therebetween;
- digital processing means for periodically performing digital computations, including:
- means for providing a flux signal representative of a desired flux level in the motor;
- and
- network means, having a transfer function which is substantially the inverse of the motor transfer function and responsive to the flux signal and to the error signal, for producing first and second output signals representative of quadrature components of motor stator current;
- means for applying the network means first output signal to the drive means first input;
- and
- means for combining the feedback signal high frequency components and the network means second output signal to provide a combined signal, and for applying the combined signal to the drive means second input.
8 more elements
An induction motor controller for controlling an induction motor operating at a substantially fixed flux level, comprising:
- drive means for causing an A.C. stator current to flow in each stator winding of the motor in response to first and second inputs thereto representative of the magnitudes of quadrature components of the stator current;
- transducer means, responsive to movement of the motor rotor, for producing a feedback signal representative of the rotor position;
- means for separating the feedback signal into high frequency and low frequency components;
- digital processing means for periodically performing digital computations, including:
- detection means, responsive to an input command signal and the feedback signal low frequency components, for providing an error signal representative of the difference therebetween;
- and
- means responsive to the feedback signal and to the error signal for providing a stator current frequency signal representative of the frequency of the A.C. stator current;
- means for summing the feedback signal high frequency components and the error signal to provide a combined signal;
- means for applying the combined signal to the drive means first input;
- and
- means for applying a signal representative of flux level to the drive means second input.
8 more elements
Dependencies are inferred from the claim text.