Leakage inductance saturation compensation for a slip control technique of a motor drive
First Claim
1. A method for controlling an induction motor having a stator and a rotor, the method comprising:
- receiving a first command designating either a desired velocity or a desired torque for the induction motor;
sensing voltage existing at the induction motor;
sensing current existing at the induction motor;
determining a rotor frequency in response to rotational speed of the rotor;
generating a current command in response to the rotor frequency, the voltage existing at the induction motor, and the first command;
deriving a leakage inductance value which varies in response to performance of the induction motor;
producing a slip frequency command in response to the leakage inductance value; and
controlling voltage applied to the motor in response to the slip frequency command, the current command, and the current existing at the induction motor.
1 Assignment
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Accused Products
Abstract
An electronic drive for vector control of an induction motor controls slip and operating frequency in response to changes in stator voltage. The drive includes a torque control loop, a flux control loop and a frequency control loop. The control is based on a commanded stator current that is resolved into a torque-producing, or q-axis, current component and a flux-producing, or d-axis, current component that are in quadrature. The frequency control loop includes slip control in which a slip frequency command is produces based on a value for the leakage inductance of the motor. The leakage inductance value dynamically varies as a function of the q-axis current reference command.
42 Citations
20 Claims
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1. A method for controlling an induction motor having a stator and a rotor, the method comprising:
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receiving a first command designating either a desired velocity or a desired torque for the induction motor;
sensing voltage existing at the induction motor;
sensing current existing at the induction motor;
determining a rotor frequency in response to rotational speed of the rotor;
generating a current command in response to the rotor frequency, the voltage existing at the induction motor, and the first command;
deriving a leakage inductance value which varies in response to performance of the induction motor;
producing a slip frequency command in response to the leakage inductance value; and
controlling voltage applied to the motor in response to the slip frequency command, the current command, and the current existing at the induction motor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for controlling an induction motor having a stator and a rotor, the method comprising:
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determining voltage feedback that is representative of stator voltage;
determining current feedback that is representative of stator current determining a rotor frequency in response to rotational speed of the rotor;
generating a current command in response to the rotor frequency, the voltage feedback, and an input command designating either a desired velocity or a desired torque for the induction motor;
deriving a leakage inductance value in response to the current command;
producing a slip frequency command in response to the leakage inductance value; and
controlling voltage applied to the stator in response to the slip frequency command, the current command, and the current feedback. - View Dependent Claims (10, 11, 13, 14, 15)
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12. The method as recited in claim 111 wherein deriving a leakage inductance value employs the q-axis current reference command.
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16. A method for controlling a three-phase induction motor having a stator and a rotor, the method comprising:
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sensing three-phase stator voltage of the induction motor;
converting the three-phase stator voltage into a q-axis voltage feedback signal and a d-axis voltage feedback signal;
determining a rotor frequency in response to rotational speed of the rotor;
generating a q-axis current reference command and a d-axis current reference command in response to the rotor frequency, the q-axis voltage feedback signal, the d-axis voltage feedback signal, and an input command designating either a desired velocity or a desired torque for the induction motor;
deriving a leakage inductance value in response to the q-axis current reference command;
producing a slip frequency command in response to the leakage inductance value, the d-axis current reference command, and the d-axis voltage feedback signal;
determining a stator operating frequency command from the rotor frequency and the slip frequency command;
sensing three-phase current flowing through the induction motor; and
controlling voltage applied to the stator in response to the stator operating frequency command, the current command and the three-phase current. - View Dependent Claims (17, 18, 19, 20)
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Specification