US4950970A
Expired / Lapsed
US
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Induction motor control system
Assignee: WESTKAMPER ENTERPRISE Inc
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Filing: 1986-03-14
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Granted: 1990-08-21
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Expires: 2006-03-14
Abstract
Abstract An improved induction motor control system. Single-phase and three-phase AC induction motors are controlled in accordance with the equation y=m=x+b, where y is the phase angle, m is the slop, x is the firing delay and b is the offset. Subsequently, the firing delay is increased by predetermined amounts, the behavior of the phase angle is evaluated for several cycles, and the motor is controlled based on the results of the evaluation, thereby minimizing energy consumption.
Inventors
- 👤 Ray E. Davis, Jr.
- 👤 Michael J. Westkamper
- 👤 Earle J. Timothy
- 👤 Richard H. Johnson
- 👤 Ronald W. Parker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 21:06
CPC Classifications
H; H02; H02J; H02J3/00; H02J3/18; H02J3/1892; H02P; H02P23/00; H02P23/26
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
122 words
A digital method for operating a single phase induction motor control system comprising the steps of: (a) energizing a single phase induction motor using a firing delay; (b) measuring the phase angle between motor voltage and motor current zero crossings; (c) computing the sum of the measured phase angle and the firing delay; (d) using the sum to automatically calculate a new phase angle generated in accordance with the algorithm: phase angle=m (firing delay)+b, where m and b are constants, m is the slope and is negative, and b is the offset and is positive; (e) comparing the measured phase angle with the newly-calculated phase angle; (f) altering the firing delay based on said comparison; and (g) repeating steps (a) through (f).
Claim 2
Dependent Claim
122 words
A digital method for operating a single phase induction motor control system comprising the steps of: (a) energizing a single phase induction motor using a firing delay; (b) measuring the phase angle between motor voltage and motor current zero crossings; (c) computing the sum of the measured phase angle and the firing delay; (d) using the sum to automatically calculate a new phase angle generated in accordance with the algorithm: phase angle=m (firing delay)+b, where m and b are constants, m is the slope and is negative, and b is the offset and is positive; (e) comparing the measured phase angle with the newly-calculated phase angle; (f) altering the firing delay based on said comparison; and (g) repeating steps (a) through (f).
Claim 3
Dependent Claim
28 words
A method according to claim 1 wherein the amount by which said firing delay is altered is proportional to the difference between the measured and newly-calculated phase angles.
Claim 4
Dependent Claim
28 words
A method according to claim 2 wherein said firing delay is increased by an amount equal to about one-half the difference between the measured and newly-calculated phase angles.
Claim 5
Dependent Claim
29 words
A method according to claim 2 wherein said firing delay is decreased by an amount equal to about four times the difference between the measured and newly-calculated phase angles.
Claim 6
Dependent Claim
38 words
A method according to claim 1 wherein: (f) the firing delay is increased based on said comparison; and (g) steps (a) through (f) are repeated until the measured phase angle and the newly-calculated phase angle are approximately equal.
Claim 7
Dependent Claim
75 words
A method according to claim 5 comprising the additional steps of: (a) measuring and storing an initial phase angle at time T o ; (b) increasing the firing delay by a predetermined amount; (c) measuring and storing the resulting phase angle at times T 1 , T 2 . . . T n ; (d) comparing said initial phase angle with the resulting phase angles; and (e) altering said firing delay based on said comparisons.
Claim 8
Dependent Claim
28 words
A method according to claim 6 wherein the phase angle at T n is less than the phase angle at T 1 and said firing delay is reduced.
Claim 9
Dependent Claim
50 words
A method according to claim 6 wherein the difference between the phase angle at T n and the phase angle at T 1 is less than one-third of the difference between the phase angle at T o and the phase angle at T 1 and said firing delay is reduced.
Claim 10
Dependent Claim
50 words
A method according to claim 6 wherein the difference between the phase angle at T n and the phase angle at T 1 is greater than one-third of the difference between the phase angle at T o and the phase angle at T 1 and the firing delay is increased.
Claim 11
Independent Claim
19 words
A method according to any of claims 1 to 9 wherein m is between about -0.1 and about -0.2.
Claim 12
Independent Claim
19 words
A method according to any of claims 1 to 9 wherein b is between about 65 and about 72.
Claim 13
Dependent Claim
117 words
A digital method for operating a three phase induction motor control system comprising the steps of: (a) energizing a three phase induction motor using a firing delay; (b) measuring the phase angle between motor voltage and motor current zero crossings; (c) computing the sum of the measured phase angle and the firing delay; (d) using the sum to automatically calculate a new phase angle generated in accordance with the algorithm: phase angle=m(firing delay)+b, where m and b are constants, m is the slope and is positive, and b is positive; (e) comparing the measured phase angle with the newly-calculated phase angle; (f) altering the firing delay based on said comparison; and (g) repeating steps (a) through (f).
Claim 14
Dependent Claim
117 words
A digital method for operating a three phase induction motor control system comprising the steps of: (a) energizing a three phase induction motor using a firing delay; (b) measuring the phase angle between motor voltage and motor current zero crossings; (c) computing the sum of the measured phase angle and the firing delay; (d) using the sum to automatically calculate a new phase angle generated in accordance with the algorithm: phase angle=m(firing delay)+b, where m and b are constants, m is the slope and is positive, and b is positive; (e) comparing the measured phase angle with the newly-calculated phase angle; (f) altering the firing delay based on said comparison; and (g) repeating steps (a) through (f).
Claim 15
Dependent Claim
28 words
A method according to claim 12 wherein the amount by which said firing delay is altered is proportional to the difference between the measured and newly-calculated phase angles.
Claim 16
Dependent Claim
28 words
A method according to claim 13 wherein said firing delay is increased by an amount equal to about one-half the difference between the measured and newly-calculated phase angles.
Claim 17
Dependent Claim
29 words
A method according to claim 13 wherein said firing delay is decreased by an amount equal to about four times the difference between the measured and newly-calculated phase angles.
Claim 18
Dependent Claim
38 words
A method according to claim 12 wherein: (f) the firing delay is increased based on said comparison; and (g) steps (a) through (f) are repeated until the measured phase angle and the newly-calculated phase angle are approximately equal.
Claim 19
Dependent Claim
75 words
A method according to claim 16 comprising the additional steps of: (a) measuring and storing an initial phase angle at time T o ; (b) increasing the firing delay by a predetermined amount; (c) measuring and storing the resulting phase angle at times T 1 , T 2 . . . T n ; (d) comparing said initial phase angle with the resulting phase angles; and (e) altering said firing delay based on said comparisons.
Claim 20
Dependent Claim
28 words
A method according to claim 17 wherein the phase angle at T n is less than the phase angle at T 1 and said firing delay is reduced.
Claim 21
Dependent Claim
50 words
A method according to claim 17 wherein the difference between the phase angle at T n and the phase angle at T 1 is less than one-third of the difference between the phase angle at T o and the phase angle at T 1 and said firing delay is reduced.
Claim 22
Dependent Claim
50 words
A method according to claim 17 wherein the difference between the phase angle at T n and the phase angle at T 1 is greater than one-third of the difference between the phase angle at T o and the phase angle at T 1 and the firing delay is increased.
Claim 23
Independent Claim
19 words
A method according to any of claims 12 to 20 wherein m is between about 0.5 and about 0.7.
Claim 24
Independent Claim
19 words
A method according to any of claims 12 to 20 wherein b is between about 10 and about 30.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-08-20 | 1994-02-19 | 1994-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-20 | 1998-02-19 | 1998-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-20 | 2002-02-19 | 2002-08-21 | $7700.00 | Window Closed / Lapsed |