US5066899A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control method of induction motor and device therefor
Assignee: Okuma Corp
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Filing: 1990-03-22
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Granted: 1991-11-19
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Expires: 2010-03-22
Abstract
Abstract An induction motor is controlled using a control device having a current control loop by detecting a current of the induction motor, and by detecting a current error corresponding to a difference between the detected current of the motor and a current command signal of the control device. The current error is processed to obtain a slip frequency. A field speed control command is generated based on the slip frequency and a motor speed of the induction motor.
Inventors
- 👤 Masayuki Nashiki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 03:32
CPC Classifications
H; H02; H02P; H02P21/00; H02P21/06; H02P21/08; H02P2207/00; H02P2207/01
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
149 words
An induction motor control device having a current control loop, said device comprising: means for detecting a current of the induction motor and for outputting corresponding current error detection signals, said current error corresponding to a difference between said current detection signals and a current command signal of the control device; slip compensation means for processing said current error detecting signals to obtain a slip compensation value and for outputting the slip compensation value; slip frequency generating means for generating and outputting a slip frequency signal based on a secondary current command of the control device; means for detecting a motor speed of the induction motor and outputting a corresponding motor speed signal; and, means for generating a field speed signal for the induction motor, said field speed signal being generated based on a sum of said slip frequency signal, said slip compensation value and said motor speed signal.
Claim 2
Dependent Claim
149 words
An induction motor control device having a current control loop, said device comprising: means for detecting a current of the induction motor and for outputting corresponding current error detection signals, said current error corresponding to a difference between said current detection signals and a current command signal of the control device; slip compensation means for processing said current error detecting signals to obtain a slip compensation value and for outputting the slip compensation value; slip frequency generating means for generating and outputting a slip frequency signal based on a secondary current command of the control device; means for detecting a motor speed of the induction motor and outputting a corresponding motor speed signal; and, means for generating a field speed signal for the induction motor, said field speed signal being generated based on a sum of said slip frequency signal, said slip compensation value and said motor speed signal.
Claim 3
Dependent Claim
134 words
An induction motor control device having a current control loop, said device comprising: means for detecting a secondary current of the induction motor and for outputting corresponding secondary current detection signals; slip compensation means for processing said secondary current detection signals and a secondary current command to obtain a slip compensation value and for outputting the slip compensation value; slip frequency generating means for generating and outputting a slip frequency signal based on a secondary current command of the control device; means for detecting a motor speed of the induction motor and outputting a corresponding motor speed signal; and, means for generating a field speed signal for the induction motor, said field speed signal being generated based on a sum of said slip frequency signal, said slip compensation value and said motor speed signal.
Claim 4
Dependent Claim
134 words
An induction motor control device having a current control loop, said device comprising: means for detecting a secondary current of the induction motor and for outputting corresponding secondary current detection signals; slip compensation means for processing said secondary current detection signals and a secondary current command to obtain a slip compensation value and for outputting the slip compensation value; slip frequency generating means for generating and outputting a slip frequency signal based on a secondary current command of the control device; means for detecting a motor speed of the induction motor and outputting a corresponding motor speed signal; and, means for generating a field speed signal for the induction motor, said field speed signal being generated based on a sum of said slip frequency signal, said slip compensation value and said motor speed signal.
Claim 5
Independent Claim
210 words
A method of controllign an induction motor using a control device having a current control loop, said method comprising the steps of: detecting N phase currents of the induction motor and outputting corresponding N current detection signals, N being a positive integer; detecting N current errors and outputting corresponding N current error detection signals, the N current errors corresponding to a difference between the N current detection signals and a corresponding one of N current command signals of the control device; processing the N current error detection signals to obtain a first slip frequency and outputting a corresponding first slip frequency signal; detecting a motor speed of the induction motor and outputting a corresponding motor speed signal; and, generating a field speed signal for the induction motor, the field speed signal being generated based on at least a sum of the first slip frequency signal and the motor speed signal; wherein said processing step includes (1) obtaining a secondary current error signal corresponding to a sum of N products, the N products corresponding to the N current error detection signals multiplied by a respective normalized phase of a secondary current command, and (2) obtaining the first slip frequency signal by subjecting the secondary current error signal to a predetermined processing.
Claim 6
Independent Claim
210 words
A method of controllign an induction motor using a control device having a current control loop, said method comprising the steps of: detecting N phase currents of the induction motor and outputting corresponding N current detection signals, N being a positive integer; detecting N current errors and outputting corresponding N current error detection signals, the N current errors corresponding to a difference between the N current detection signals and a corresponding one of N current command signals of the control device; processing the N current error detection signals to obtain a first slip frequency and outputting a corresponding first slip frequency signal; detecting a motor speed of the induction motor and outputting a corresponding motor speed signal; and, generating a field speed signal for the induction motor, the field speed signal being generated based on at least a sum of the first slip frequency signal and the motor speed signal; wherein said processing step includes (1) obtaining a secondary current error signal corresponding to a sum of N products, the N products corresponding to the N current error detection signals multiplied by a respective normalized phase of a secondary current command, and (2) obtaining the first slip frequency signal by subjecting the secondary current error signal to a predetermined processing.
Claim 7
Dependent Claim
44 words
A method as recited in claim 3, further comprising: obtaining a second slip frequency signal corresponding to the secondary current command; wherein the field speed signal is based on a sum of the first and second slip frequency signals and the motor speed signal.
Claim 8
Dependent Claim
44 words
A method as recited in claim 3, further comprising: obtaining a field current command in accordance with the motor speed signal; and, generating the N current command signals in accordance with the field current command, the secondary current command, and the field speed signal.
Claim 9
Dependent Claim
44 words
A method as recited in claim 4, further comprising: obtaining a field current command in accordance with the motor speed signal; and, generating the N current command signals in accordance with the field current command, the secondary current command, and the field speed signal.
Claim 10
Dependent Claim
18 words
A method as recited in claim 3, wherein the predetermined processing of said processing step is PID processing.
Claim 11
Dependent Claim
18 words
A method as recited in claim 6, wherein the predetermined processing of said processing step is PID processing.
Claim 12
Dependent Claim
35 words
A method as recited in claim 4, wherein the second slip frequency signal is obtained by multiplying the second current command by a coefficient corresponding to at least a secondary resistance of the induction motor.
Claim 13
Dependent Claim
35 words
A method as recited in claim 6, wherein the second slip frequency signal is obtained by multiplying the second current command by a coefficient corresponding to at least a secondary resistance of the induction motor.
Claim 14
Dependent Claim
35 words
A method as recited in claim 8, wherein the second slip frequency signal is obtained by multiplying the second current command by a coefficient corresponding to at least a secondary resistance of the induction motor.
Claim 15
Dependent Claim
55 words
A method as recited in claim 3, wherein N equals three, and wherein the secondary current error signal is obtained in accordance with the following equation: ##EQU6## where S SE =secondary current error signal, I UE , I VE , I WE =respective current error detection signals, Θ.sub. = phase angle of secondary current command.
Claim 16
Dependent Claim
55 words
A method as recited in claim 4, wherein N equals three, and wherein the secondary current error signal is obtained in accordance with the following equation: ##EQU7## where S SE =secondary current error signal, I UE , I VE , I WE =respective current error detection signals, Θ.sub. = phase angle of secondary current command.
Claim 17
Dependent Claim
55 words
A method as recited in claim 6, wherein N equals three, and wherein the secondary current error signal is obtained in accordance with the following equation: ##EQU8## where S SE =secondary current error signal, I UE , I VE , I WE =respective current error detection signals, Θ.sub. = phase angle of secondary current command.
Claim 18
Dependent Claim
55 words
A method as recited in claim 8, wherein N equals three, and wherein the secondary current error signal is obtained in accordance with the following equation: ##EQU9## where S SE =secondary current error signal, I UE , I VE , I WE =respective current error detection signals, Θ.sub. = phase angle of secondary current command.
Claim 19
Dependent Claim
55 words
A method as recited in claim 11, wherein N equals three, and wherein the secondary current error signal is obtained in accordance with the following equation: ##EQU10## where S SE =secondary current error signal, I UE , I VE , I WE =respective current error detection signals, Θ.sub. = phase angle of secondary current command.
Claim 20
Dependent Claim
63 words
A method as recited in claim 5, further comprising: obtaining N voltage commands in accordance with the secondary current command, the field current command and the field speed signal, and in accordance with a primary resistance, secondary resistance and inductance of the induction motor; adding the thus obtained N voltage commands to prior N voltage signals to be applied to the induction motor.
Claim 21
Dependent Claim
63 words
A method as recited in claim 10, further comprising: obtaining N voltage commands in accordance with the secondary current command, the field current command and the field speed signal, and in accordance with a primary resistance, secondary resistance and inductance of the induction motor; adding the thus obtained N voltage commands to prior N voltage signals to be applied to the induction motor.
Claim 22
Dependent Claim
63 words
A method as recited in claim 14, further comprising: obtaining N voltage commands in accordance with the secondary current command, the field current command and the field speed signal, and in accordance with a primary resistance, secondary resistance and inductance of the induction motor; adding the thus obtained N voltage commands to prior N voltage signals to be applied to the induction motor.
Claim 23
Dependent Claim
63 words
A method as recited in claim 16, further comprising: obtaining N voltage commands in accordance with the secondary current command, the field current command and the field speed signal, and in accordance with a primary resistance, secondary resistance and inductance of the induction motor; adding the thus obtained N voltage commands to prior N voltage signals to be applied to the induction motor.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1994-11-18 | 1995-05-20 | 1995-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-11-18 | 1999-05-20 | 1999-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-11-18 | 2003-05-20 | 2003-11-19 | $7700.00 | Window Closed / Lapsed |