Apparatus and method for controlling torque of induction motor through vector control type inverter
First Claim
1. An apparatus for controlling a torque of an induction motor through a vector control method type inverter, comprising:
- a) a detector arranged for detecting a velocity ω
r of a rotor of the induction motor;
b) an output frequency calculator arranged for calculating an output frequency ω
1 of the induction motor from the detected rotor velocity ω
r;
c) a model calculator having a model equivalent to the induction motor and arranged for calculating at least a secondary induced voltage E2 * of the model from a torque current instruction IT*, a secondary magnetic flux instruction λ
2d *, and the output frequency ω
1 ;
d) an induced voltage and magnetic flux calculator arranged for calculating at least a secondary induced voltage E2 from a primary voltage and current of the induction motor;
e) an error characteristic variable extracting circuit arranged for deriving a deviation between the calculated secondary induced voltages by said induced voltage and magnetic flux calculator and said model calculator 9 and extracting and outputting an error characteristic variable corresponding to a variation in a secondary resistance of the induction motor from the deviation therebetween as a one-dimensional component;
f) a slip calculator arranged for calculating a slip frequency ω
s from the secondary magnetic instruction λ
2d *, the torque current instruction IT*, and the secondary resistance R2 '"'"' of the induction motor; and
g) a compensation circuit arranged for correcting the slip frequency calculation of said slip calculator used to perform a vector control for the induction motor by a temperature variation in the secondary resistance of the induction motor according to an output variable of said error characteristic variable extracting circuit,wherein said apparatus further comprises a skin effect correction circuit having a non-linear function table and arranged for deriving an error component developed in an output of said compensation circuit when a leakage inductance of the induction motor is non-liearly varied due to a skin effect from the non-linear function table corresponding to the detected velocity ω
r of the rotor of the induction motor and at least either of the torque current instruction IT* or torque instruction Trq and an adder arranged for adding the outputted error component of said skin effect correction circuit to the output variable of said error characteristic variable extracting circuit.
1 Assignment
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Accused Products
Abstract
In apparatus and method for controlling a torque of an induction motor through a vector control method type inverter having a slip frequency calculator arranged for calculating a slip frequency used to perform a vector control for the induction motor and a secondary resistance compensation circuit arranged for correcting the slip frequency by a temperature variation in a secondary resistance of the induction motor, basically a skin effect correction circuit is added for deriving an error component developed in an output of the secondary resistance compensation circuit when a leakage inductance Lσis non-linearly varied due to a skin effect phenomenon.
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Citations
13 Claims
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1. An apparatus for controlling a torque of an induction motor through a vector control method type inverter, comprising:
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a) a detector arranged for detecting a velocity ω
r of a rotor of the induction motor;b) an output frequency calculator arranged for calculating an output frequency ω
1 of the induction motor from the detected rotor velocity ω
r;c) a model calculator having a model equivalent to the induction motor and arranged for calculating at least a secondary induced voltage E2 * of the model from a torque current instruction IT*, a secondary magnetic flux instruction λ
2d *, and the output frequency ω
1 ;d) an induced voltage and magnetic flux calculator arranged for calculating at least a secondary induced voltage E2 from a primary voltage and current of the induction motor; e) an error characteristic variable extracting circuit arranged for deriving a deviation between the calculated secondary induced voltages by said induced voltage and magnetic flux calculator and said model calculator 9 and extracting and outputting an error characteristic variable corresponding to a variation in a secondary resistance of the induction motor from the deviation therebetween as a one-dimensional component; f) a slip calculator arranged for calculating a slip frequency ω
s from the secondary magnetic instruction λ
2d *, the torque current instruction IT*, and the secondary resistance R2 '"'"' of the induction motor; andg) a compensation circuit arranged for correcting the slip frequency calculation of said slip calculator used to perform a vector control for the induction motor by a temperature variation in the secondary resistance of the induction motor according to an output variable of said error characteristic variable extracting circuit, wherein said apparatus further comprises a skin effect correction circuit having a non-linear function table and arranged for deriving an error component developed in an output of said compensation circuit when a leakage inductance of the induction motor is non-liearly varied due to a skin effect from the non-linear function table corresponding to the detected velocity ω
r of the rotor of the induction motor and at least either of the torque current instruction IT* or torque instruction Trq and an adder arranged for adding the outputted error component of said skin effect correction circuit to the output variable of said error characteristic variable extracting circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for controlling a torque of an induction motor through a vector control method type inverter, said method comprising the steps of:
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a) detecting a velocity ω
r of a rotor of the induction motor;b) calculating an output frequency ω
1 of the induction motor from the detected rotor velocity ω
r;c) providing a model equivalent to the induction motor and calculating at least a secondary induced voltage E2 * of the model from a torque current instruction IT*, a secondary magnetic flux instruction λ
2d *, and the output frequency ω
1 ;d) calculating at least a secondary induced voltage E2 from a primary voltage and current of the induction motor; e) deriving a deviation between the calculated secondary induced voltages at the step d) and step c) and extracting and outputting an error characteristic variable corresponding to a variation in a secondary resistance of the induction motor from the deviation therebetween as a one-dimensional component; f) calculating a slip frequency ω
s from the secondary magnetic instruction λ
2d *, the torque current instruction IT*, and the secondary resistance R2 '"'"' of the induction motor; andg) correcting the slip frequency calculation used to perform a vector control for the induction motor by a temperature variation in the secondary resistance of the induction motor according to an output variable at the step e), wherein said method further comprises the steps of;
h) providing a non-linear function table;
i) deriving an error component developed in an output of a compensation circuit when a leakage inductance of the induction motor is non-linearly varied due to a skin effect from the non-linear function table corresponding to the detected velocity CO r of the rotor of the induction motor and at least either of the torque current instruction IT* or torque instruction Trq; and
J) adding the outputted error component to the output variable outputted at the step e).
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Specification