Method of and apparatus for controlling the operation of an induction motor using a model of the induction motor
AssigneeA. O. Smith Corporation
InventorBrian Thomas Branecky
Life of this patent
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Abstract
A controller for a motor and a method for controlling the operation of the motor. The controller includes a model of the motor, where the model is utilized to determine modeled values of first and second motor variables. An estimated value of slip is adjusted based at least in part on a comparison of the modeled value of the second motor variable and an estimated value of the second motor variable which is based at least in part on a value of bus voltage and a value of bus current. As the estimated value of slip is adjusted, the modeled values are updated and the voltage utilized to energize the motor is thereby updated to provide control of the motor based on the control of the first motor variable.
Claims66
A method of controlling an induction motor, the method comprising:
- providing a model of the motor, wherein the model is utilized to provide a modeled value of torque and a modeled value of torque producing current;
- supplying a voltage to the motor to energize the motor;
- providing a commanded value of torque;
- measuring a bus voltage and a bus current;
- determining an estimated value of torque producing current based at least in part on the bus voltage and the bus current;
- comparing the estimated and modeled values of torque producing current to determine a torque producing current error;
- using the model to determine an updated modeled value of torque based at least in part on the torque producing current error;
- adjusting the voltage supplied to the motor based at least in part on the updated modeled value of torque.
A method of controlling an induction motor, the method comprising:
- providing a model of the motor, wherein the model is utilized to provide a modeled value of torque and a modeled value of power factor;
- supplying a voltage to the motor to energize the motor;
- providing a commanded value of torque;
- measuring a bus voltage and a bus current;
- determining an estimated value of power factor based at least in part on the bus voltage and the bus current;
- comparing the estimated and modeled values of power factor to determine a power factor error;
- using the model to determine an updated modeled value of torque based at least in part on the power factor error;
- adjusting the voltage supplied to the motor based at least in part on the updated modeled value of torque.
A method of controlling an induction motor, the method comprising:
- providing a model of the motor, wherein the model is utilized to provide a modeled value of torque and a modeled value of motor current;
- supplying a voltage to the motor to energize the motor;
- providing a commanded value of torque;
- measuring a bus voltage and a bus current;
- determining an estimated value of motor current based at least in part on the bus voltage and the bus current;
- comparing the estimated and modeled values of motor current to determine a motor current error;
- using the model to determine an updated modeled value of torque based at least in part on the motor current error;
- adjusting the voltage supplied to the motor based at least in part on the updated modeled value of torque.
A method of controlling a motor, the method comprising the acts of:
- providing a model of the motor, wherein the model is utilized to provide a modeled value of a first motor variable and a modeled value of a second motor variable;
- supplying a voltage to the motor with an inverter, the inverter including a bus voltage and a bus current;
- providing a commanded value of the first motor variable;
- measuring the bus voltage and the bus current;
- determining an estimated value of the second motor variable based at least in part on the bus voltage and the bus current;
- comparing the estimated and modeled values of the second motor variable to determine a second motor variable error;
- using the model to determine an updated modeled value of the first motor variable based at least in part on the second motor variable error;
- adjusting the voltage supplied to the motor based at least in part on the modeled value of the first motor variable.
A controller for an induction motor having a first motor variable and a second motor variable, the controller comprising:
- a motor model module configured to represent a motor, the motor model module having an input that receives an estimated value of slip and an output that outputs a modeled value of the first motor variable and a modeled value of the second motor variable;
- an inverter having a bus voltage and a bus current, the inverter supplying a voltage to the induction motor to energize the induction motor;
- a measuring circuit configured to measure the bus voltage and the bus current;
- a calculator configured to calculate an estimated value of the second motor variable based at least in part on the measured bus voltage and the measured bus current;
- a first comparator having an input that receives the estimated and modeled values of the second motor variable, and an output that outputs a second motor variable error;
- a regulator having an input that receives the second motor variable error, and an output that outputs the estimated value of slip;
- and
- a second comparator having an input that receives a commanded value of the first motor variable and the modeled value of a first motor variable, and an output that outputs a first motor variable error;
- wherein the voltage is determined based at least in part on the first motor variable error.
A controller for an induction motor having a first motor variable, the controller comprising:
- an inverter having a bus voltage and a bus current, the inverter being operable to receive a command signal, and to supply a voltage to the induction motor based at least in part on the command signal;
- a measuring circuit operable to measure a value of the bus voltage and a value of the bus current;
- a programmable device operable to generate an estimated value of slip based at least in part on the measured values of the bus voltage and the bus current, to maintain a model of the induction motor, and to adjust the command signal based at least in part on a modeled value of the first motor variable generated using the model, the modeled value of the first motor variable being based at least in part on the estimated value of slip.
Dependencies are inferred from the claim text.