Patent US3447750A successfully refreshed from Google Patents.
US4456868A
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US
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Method and apparatus for controlling AC motors
Assignee: Fanuc Corp
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Filing: 1982-03-30
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Granted: 1984-06-26
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Expires: 2002-03-30
Abstract
Abstract An AC motor control method and apparatus therefor, for controlling an AC motor 11 by holding the excitation current I 0 of the AC motor 11 constant and varying primary current I 1 in accordance with a speed deviation Δn. Stored previously in a memory device 18 are a torque T-slip frequency ω s characteristic, a slip frequency ω s -primary current vector I 1 characteristic, and a slip frequency ω s and phase φ 1 characteristic which take secondary leakage reactance into account. Slip frequency ω s , primary current vector I 1 and phase φ 1 are read out of the memory device in accordance with the torque command T obtained from the speed deviation Δn, whereby three-phase current commands i u , i v , i w are produced. Accordingly, torque irregularity is suppressed and an excellent response obtained.
Inventors
- 👤 Sakae Yamamura
- 👤 Shigeki Kawada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:19
CPC Classifications
H; H02; H02P; H02P21/00; H02P21/06; H02P21/08; H02P21/09
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
179 words
An AC motor control method comprising the steps of: (a) a step of obtaining slip frequency, phase difference and primary current amplitude using a speed command and an actual speed; (b) a step of determining angular frequency in accordance with the actual speed of the AC motor; (c) a step of producing a three-phase current command having a frequency by using the slip frequency, phase difference and primary current amplitude obtained in step (a), as well as said angular frequency; and (d) a step of driving the AC motor by said three-phase current command, wherein step (a) includes i computing a torque command from a deviation between said speed command signal and actual speed, where a torque-slip frequency relation and a slip frequency-primary current vector relation which take the secondary leakage reactance of said AC motor into account are predetermined; ii finding said slip frequency using the torque command obtained in step (i) and the torque-slip frequency relation; and then iii finding said primary current amplitude and phase difference using said slip frequency and slip frequency-primary current vector relation.
Claim 2
Dependent Claim
179 words
An AC motor control method comprising the steps of: (a) a step of obtaining slip frequency, phase difference and primary current amplitude using a speed command and an actual speed; (b) a step of determining angular frequency in accordance with the actual speed of the AC motor; (c) a step of producing a three-phase current command having a frequency by using the slip frequency, phase difference and primary current amplitude obtained in step (a), as well as said angular frequency; and (d) a step of driving the AC motor by said three-phase current command, wherein step (a) includes i computing a torque command from a deviation between said speed command signal and actual speed, where a torque-slip frequency relation and a slip frequency-primary current vector relation which take the secondary leakage reactance of said AC motor into account are predetermined; ii finding said slip frequency using the torque command obtained in step (i) and the torque-slip frequency relation; and then iii finding said primary current amplitude and phase difference using said slip frequency and slip frequency-primary current vector relation.
Claim 3
Dependent Claim
34 words
An AC motor control method according to claim 1, further including a step of obtaining the frequency of the primary current by adding the slip frequency obtained in step (a), and the angular frequency.
Claim 4
Dependent Claim
29 words
An AC motor control method according to claim 1, further including a step of passing a direct excitation current through stator windings when the AC motor is at rest.
Claim 5
Dependent Claim
50 words
An AC motor control method according claim 1, characterized in step (iii) includes finding a primary current for a slip frequency of zero from said slip frequency-primary current vector relation and employing this primary current as an excitation current passed through the stator windings when the motor is at rest.
Claim 6
Dependent Claim
35 words
An AC motor control method according to claim 1, including a step of finding a positional offset between a commanded position and a current position and generating said speed command corresponding to said positional offset.
Claim 7
Dependent Claim
186 words
An AC motor control apparatus including: a speed sensor for sensing the actual speed of the AC motor; angular frequency detection means for providing an angular frequency signal in accordance with the actual speed of the AC motor; torque command generating means for generating a torque command on the basis of a speed deviation between a speed command and an actual speed from said speed sensor; memory means for storing a torque-slip frequency characteristic, a slip frequency-amplitude characteristic and a slip frequency-phase characteristic which take secondary leakage reactance into account, for providing a slip frequency in accordance with said torque command and said torque-slip frequency characteristic, for providing a primary current amplitude in accordance with said slip frequency and said slip frequency-amplitude characteristic, and for providing a phase signal in accordance with said slip frequency and said slip frequency-phase charcteristic; an arithmetic circuit for computing a three-phase current command from said slip frequency, said primary current amplitude, said phase signal, and from said angular frequency signal; and a drive circuit for driving the AC motor by means of the three-phase current command from said arithmetic circuit.
Claim 8
Dependent Claim
186 words
An AC motor control apparatus including: a speed sensor for sensing the actual speed of the AC motor; angular frequency detection means for providing an angular frequency signal in accordance with the actual speed of the AC motor; torque command generating means for generating a torque command on the basis of a speed deviation between a speed command and an actual speed from said speed sensor; memory means for storing a torque-slip frequency characteristic, a slip frequency-amplitude characteristic and a slip frequency-phase characteristic which take secondary leakage reactance into account, for providing a slip frequency in accordance with said torque command and said torque-slip frequency characteristic, for providing a primary current amplitude in accordance with said slip frequency and said slip frequency-amplitude characteristic, and for providing a phase signal in accordance with said slip frequency and said slip frequency-phase charcteristic; an arithmetic circuit for computing a three-phase current command from said slip frequency, said primary current amplitude, said phase signal, and from said angular frequency signal; and a drive circuit for driving the AC motor by means of the three-phase current command from said arithmetic circuit.
Claim 9
Dependent Claim
57 words
An AC motor control apparatus according to claim 6, further including a position detector for detecting the current position of a movable element driven by the AC motor, and speed command generating means for obtaining an offset between said detected curent position and a commanded position and for generating a speed command in accordance with said offset.
Claim 10
Independent Claim
215 words
A method for controlling an AC motor in accordance with a slip frequency, a phase difference, a primary current amplitude, a commanded speed and an actual speed, said method comprising the steps of: (a) computing a torque command in accordance with the difference between said commanded speed and said actual speed; (b) computing the slip frequency in accordance with the torque command, and the following relation ##EQU11## wherein T corresponds to said torque command, and ##EQU12## where r 2 is the secondary resistance, 1 m is the excitation inductance, 1 2 is the secondary leakage inductance, w s is the slip frequency and I o is the excitation current; (c) computing the primary current amplitude using said slip frequency and the following equation ##EQU13## wherein k 3 1 2 2 , k 4 =1/r 2 2 ·21 2 (1 2 +1 m )+r 2 2 1 m 2 ), and ##EQU14## (d) computing a phase difference using said slip frequency and the following relation ##EQU15## (e) determining an angular frequency in accordance with the actual speed of AC motor; (f) generating a three-phase primary current command using the slip frequency, the phase difference, the primary current amplitude and the angular frequency; and (g) driving the AC motor in accordance with said three-phase primary current command.
Claim 11
Independent Claim
215 words
A method for controlling an AC motor in accordance with a slip frequency, a phase difference, a primary current amplitude, a commanded speed and an actual speed, said method comprising the steps of: (a) computing a torque command in accordance with the difference between said commanded speed and said actual speed; (b) computing the slip frequency in accordance with the torque command, and the following relation ##EQU11## wherein T corresponds to said torque command, and ##EQU12## where r 2 is the secondary resistance, 1 m is the excitation inductance, 1 2 is the secondary leakage inductance, w s is the slip frequency and I o is the excitation current; (c) computing the primary current amplitude using said slip frequency and the following equation ##EQU13## wherein k 3 1 2 2 , k 4 =1/r 2 2 ·21 2 (1 2 +1 m )+r 2 2 1 m 2 ), and ##EQU14## (d) computing a phase difference using said slip frequency and the following relation ##EQU15## (e) determining an angular frequency in accordance with the actual speed of AC motor; (f) generating a three-phase primary current command using the slip frequency, the phase difference, the primary current amplitude and the angular frequency; and (g) driving the AC motor in accordance with said three-phase primary current command.
References Cited (Backward Citations)
US3851234A
Cited
US4310791A
Cited
US4327313A
Cited
US4292577A
Cited
US4281276A
Cited
US4311951A
Cited
GB2056710A
Cited
US4392100A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-06-26 | 1987-12-26 | 1988-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-06-26 | 1991-12-26 | 1992-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-06-26 | 1995-12-26 | 1996-06-26 | $7700.00 | Window Closed / Lapsed |