US4422040A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of testing stepping motors
Assignee: International Business Machines Corp
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Filing: 1981-11-05
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Granted: 1983-12-20
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Expires: 2001-11-05
Abstract
Abstract A method for quickly testing stepping motors (10). The motor phases (ΦA-ΦC) are connected in series, and a constant current is applied to the phases. The rotor (12) of the motor (10) under test is rotated unidirectionally at a constant speed, and the voltage drop across each phase is measured and converted into back EMF. The back EMF is then analyzed to determine a characteristic of the motor (10), for example stepping accuracy of each of the phases, or related torque information, and the result of the analysis is then compared with a predetermined motor parameter to provide comparison data or a signal of a pass or fail condition based upon the comparison.
Inventors
- 👤 Jerry W. Raider
- 👤 II Earl D. Ward
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:08
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/34
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
90 words
A method of testing a stepping motor having a stator with a plurality of phases and a rotor, comprising the steps of: connecting the phases of the motor under test in series; applying a constant current to said phases; rotating said rotor of said motor at a constant speed; detecting a voltage drop across at least one phase and converting said detected voltage drop into back EMF for said at least one phase; analyzing the back EMF of at least said one phase to determine a parameter of said motor.
Claim 2
Independent Claim
90 words
A method of testing a stepping motor having a stator with a plurality of phases and a rotor, comprising the steps of: connecting the phases of the motor under test in series; applying a constant current to said phases; rotating said rotor of said motor at a constant speed; detecting a voltage drop across at least one phase and converting said detected voltage drop into back EMF for said at least one phase; analyzing the back EMF of at least said one phase to determine a parameter of said motor.
Claim 3
Dependent Claim
32 words
A method of testing a stepping motor in accordance with claim 1 including the steps of comparing said parameter with a known comparable parameter to determine the acceptability of said stepping motor.
Claim 4
Independent Claim
36 words
A method in accordance with claims 1 or 2 including the steps of detecting the voltage drop across each phase and converting the detected voltage of each phase into back EMF for each of said phases.
Claim 5
Dependent Claim
37 words
A method in accordance with claim 3 including the steps of analyzing the back EMF of said phase to determine the stepping accuracy of said phase, and comparing the determined stepping accuracy with a predetermined stepping accuracy.
Claim 6
Dependent Claim
47 words
A method in accordance with claim 3 including the steps of analyzing the back EMF of each said phases by applying several constant current levels to determine the running torque of said motor, and comparing the determined running torque of said motor with a predetermined running torque.
Claim 7
Dependent Claim
52 words
A method in accordance with claim 3 including the steps of measuring the time for a predetermined current rise after application of current to said series connected phases, and analyzing said current rise to determine the average inductance of said phases, and comparing the determined average inductance with a predetermined average inductance.
Claim 8
Dependent Claim
38 words
A method in accordance with claim 3 including the steps of analyzing the back EMF of each of said phases to determine the hysteretic losses of said motor, and comparing the hysteretic losses with a predetermined hysteretic loss.
Claim 9
Dependent Claim
43 words
A method in accordance with claim 3 including the steps of analyzing the back EMF of each of said phases to determine the phase-to-phase variation in torque between said phases, and comparing the phase-to-phase variation in said torque with a predetermined phase-to-phase variation.
Claim 10
Dependent Claim
47 words
A method in accordance with claim 3 including the steps of analyzing the back EMF of each of said phases to determine the back EMF variation per revolution of said motor, and comparing the back EMF variation per revolution with a predetermined back EMF variation per revolution.
Claim 11
Dependent Claim
41 words
A method in accordance with claim 3 including the steps of analyzing the back EMF of each of said phases to determine the damping potential of said motor, and comparing the damping potential of said motor with a predetermined damping potential.
Claim 12
Dependent Claim
48 words
A method in accordance with claim 3 including the steps of analyzing the back EMF of each of said phases to determine the gap width between the rotor of said motor and the stator of said motor, and comparing the determined gap width with a predetermined gap width.
Claim 13
Dependent Claim
44 words
A method in accordance with claim 3 including the steps of analyzing the total voltage across all of said phases to determine average resistance and the absence of shorts in each of said phases, and comparing the value found thereby with a predetermined value.
Claim 14
Dependent Claim
36 words
A method in accordance with claim 12 including the step of analyzing said value found to determine the harmonic content of each of said phases, and comparing the determined harmonic content with a predetermined harmonic content.
Claim 15
Dependent Claim
50 words
A method in accordance with claim 3 including the step of measuring the voltage drop across all of said phases at a known current through said phases, analyzing said voltage drop across said phases to determine the resistance of said phases, and comparing the determined resistance with a predetermined resistance.
Claim 16
Independent Claim
126 words
A method of testing a stepping motor having a stator with a plurality of phases and a rotor for rotation within said stator, comprising the steps of: coupling the rotor of said motor to a source of constant speed, unidirectional rotation; connecting the phases of said motor in series; connecting a controlled, constant current source in series with said series connected phases of said motor; rotating the rotor of said motor at a constant speed; applying a constant current through the series connected phases of said motor; measuring the voltage drop across each of said phases and converting said voltage drop into back EMF for each of said phases, and analyzing said back EMF of said phases to determine a plurality of parameters of said motor.
Claim 17
Independent Claim
126 words
A method of testing a stepping motor having a stator with a plurality of phases and a rotor for rotation within said stator, comprising the steps of: coupling the rotor of said motor to a source of constant speed, unidirectional rotation; connecting the phases of said motor in series; connecting a controlled, constant current source in series with said series connected phases of said motor; rotating the rotor of said motor at a constant speed; applying a constant current through the series connected phases of said motor; measuring the voltage drop across each of said phases and converting said voltage drop into back EMF for each of said phases, and analyzing said back EMF of said phases to determine a plurality of parameters of said motor.
Claim 18
Dependent Claim
31 words
A method of testing in accordance with claim 14 including the steps of comparing said plurality of motor parameters with predetermined known parameters, and determining therefrom the acceptability of said motor.
Claim 19
Dependent Claim
30 words
A method in accordance with claim 15 or 16 including the steps of analyzing the back EMF of each of said phases to determine the hysteretic losses of said motor.
Claim 20
Dependent Claim
32 words
A method in accordance with claim 15 or 16 including the steps of analyzing the back EMF of each of said phases to determine the phase-to-phase variation in torque between said phases.
Claim 21
Dependent Claim
33 words
A method in accordance with claim 15 or 16 including the steps of analyzing the back EMF of each of said phases to determine the back EMF variation per revolution of said motor.
Claim 22
Dependent Claim
30 words
A method in accordance with claim 15 or 16 including the steps of analyzing the back EMF of each of said phases to determine the damping potential of said motor.
Claim 23
Dependent Claim
39 words
A method in accordance with claim 15 or 16 including the steps of analyzing the back EMF of each of said phases to determine the gap width between the rotor of said motor and the stator of said motor.
Claim 24
Dependent Claim
37 words
A method in accordance with claim 15 or 16 including the steps of measuring the voltage drop across all said phases, and analyzing the measured value to determine the absence of shorts in each of said phases.
Claim 25
Dependent Claim
24 words
A method in accordance with claim 22 including the step of analyzing said measured value found to determine the harmonic content of said phase.
Claim 26
Dependent Claim
27 words
A method in accordance with claim 22 including the step of analyzing the measured value found of all said phases to determine the resistance of said phases.
Claim 27
Dependent Claim
52 words
A method in accordance with claim 15 or 16 including the steps of measuring the time for current rise after application of current to said series connected phases, and analyzing said current rise to determine the average inductance of said phases, and comparing the determined average inductance with a predetermined average inductance.
Claim 28
Independent Claim
94 words
A method of testing a stepping motor having a stator with a plurality of phases and a rotor, comprising the steps of: applying a constant current at at least one of several current levels to one or more of said plurality of phases; rotating said rotor of said motor at a constant speed; detecting a voltage drop across at least one phase and converting said detected voltage drop into back EMF for said at least one phase; analyzing the back EMF of at least said one phase to determine a parameter of said motor.
Claim 29
Independent Claim
94 words
A method of testing a stepping motor having a stator with a plurality of phases and a rotor, comprising the steps of: applying a constant current at at least one of several current levels to one or more of said plurality of phases; rotating said rotor of said motor at a constant speed; detecting a voltage drop across at least one phase and converting said detected voltage drop into back EMF for said at least one phase; analyzing the back EMF of at least said one phase to determine a parameter of said motor.
Claim 30
Dependent Claim
23 words
A method of testing a stepping motor in accordance with claim 26 including the step of connecting all of said phases in series.
Claim 31
Dependent Claim
17 words
A method in accordance with claim 26 wherein at least one of said current levels is zero.
Claim 32
Independent Claim
46 words
A method in accordance with claims 26 or 27 or 28 including the steps of analyzing the back EMF of each of said phases to determine the running torque of said motor, and comparing the determined running torque of said motor with a predetermined running torque.
References Cited (Backward Citations)
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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) | 1986-12-19 | 1987-06-20 | 1987-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-19 | 1991-06-20 | 1991-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-19 | 1995-06-20 | 1995-12-20 | $7700.00 | Window Closed / Lapsed |