US4250435A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Clock rate control of electronically commutated motor rotational velocity
Assignee: General Electric Co
•
Filing: 1980-01-04
•
Granted: 1981-02-10
•
Expires: 2000-01-04
Abstract
Abstract A speed control system for an electrically commutated motor which is readily adaptable to digital velocity control input and which provides highly efficient and accurate control in a relatively inexpensive manner. Desired motor rotational velocity is commanded by an input clock rate, which may be variable, rather than by a voltage or current signal. A sensor is provided for determining actual rotor position, and actual rotor position is periodically compared with instantaneous desired motor position as indicated by the time of occurance of one of the input clock signals or pulses. Depending upon the results of this periodic comparison, a dynamically established active current limit is modified. Specifically, if motor rotor actual position leads desired position, the current limit is reduced. If, on the other hand, actual motor position is lagging, the current limit is increased. If the rotor is at the correct position, or within a predetermined deadband, the current limit is unchanged. This control action occurs simultaneously with conventional winding commutation taking place under the control of a, commutation sequencer periodically advanced in conventional fashion as the rotor reaches each of a plurality of predetermined positions.
Inventors
- 👤 Robert P. Alley
- 👤 Richard C. Weischedel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:11
CPC Classifications
H; H02; H02P; H02P6/00; H02P6/08; H02P6/14; H02P6/15; H02P6/153
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
235 words
A speed control system for an electronically commutated motor having a rotor and a plurality of stator windings operable to produce magnetic fields in response to selective winding energization, said system comprising: a commutation sequencer operable to selectively energize the motor windings in a sequence appropriate for effecting motor rotor rotation, said commutation sequencer operable to advance step-by-step through the sequence as the rotor reaches each of a plurality of predetermined positions; a storage device for storing a changeable representation of an established limit for motor winding current; a controller responsive to said representation for limiting current through motor windings energized by said sequencer to the established limit; a sensor for determining actual rotor position; a source of periodic signals representative of desired rotor position and occurring at a rate proportional to desired rotational velocity, the time of occurrence of each individual one of the periodic signals representative of a particular instantaneous desired rotor position; and and adjustment element responsive to said sensor and to said periodic signal source, said adjustment element operable to periodically compare actual rotor position to desired rotor position and to decrease the established limit for motor winding current in the event actual rotor position leads desired rotor position by at least a predetermined amount, and to increase the established limit for motor winding current in the event actual rotor position lags desired rotor position by at least a predetermined amount.
Claim 2
Dependent Claim
235 words
A speed control system for an electronically commutated motor having a rotor and a plurality of stator windings operable to produce magnetic fields in response to selective winding energization, said system comprising: a commutation sequencer operable to selectively energize the motor windings in a sequence appropriate for effecting motor rotor rotation, said commutation sequencer operable to advance step-by-step through the sequence as the rotor reaches each of a plurality of predetermined positions; a storage device for storing a changeable representation of an established limit for motor winding current; a controller responsive to said representation for limiting current through motor windings energized by said sequencer to the established limit; a sensor for determining actual rotor position; a source of periodic signals representative of desired rotor position and occurring at a rate proportional to desired rotational velocity, the time of occurrence of each individual one of the periodic signals representative of a particular instantaneous desired rotor position; and and adjustment element responsive to said sensor and to said periodic signal source, said adjustment element operable to periodically compare actual rotor position to desired rotor position and to decrease the established limit for motor winding current in the event actual rotor position leads desired rotor position by at least a predetermined amount, and to increase the established limit for motor winding current in the event actual rotor position lags desired rotor position by at least a predetermined amount.
Claim 3
Dependent Claim
31 words
A speed control system according to claim 1, wherein said source of periodic signals generates the periodic signals at a controlled variable rate such that motor rotational velocity is correspondingly varied.
Claim 4
Dependent Claim
24 words
A speed control system according to claim 1, wherein said sensor is operable to output a signal when the rotor reaches a predetermined position.
Claim 5
Dependent Claim
38 words
A speed control system according to claim 3, which further comprises a connection from said sensor effective to advance said commutation sequencer when the rotor reaches each of a plurality of predetermined positions as sensed by said sensor.
Claim 6
Dependent Claim
129 words
A speed control system according to claim 3, wherein said adjustment element comprises: a phase comparator connected to receive signals from said sensor and from said source of periodic signals and, when a signal has been received from each of said sensor and said source, to output a signal indicating which of said received signals occurred first in time; means responsive to the output of said phase comparator for decreasing or increasing the established motor winding current limit, the current limit being decreased in the event the signal from said sensor preceeds the signal from said source by at least a predetermined amount, and the current limit being increased in the event the signal from said sensor follows the signal from said source by at least a predetermined amount.
Claim 7
Dependent Claim
81 words
A speed control system according to claim 3 wherein said sensor comprises: an integrator operable to integrate, with respect to time from an initial state, sampled voltage induced in a motor winding not currently energized, thereby to develop a voltage integral; and a comparator operable to compare the voltage integral to a predetermined reference voltage level and to provide an output signal when the voltage integral exceeds the reference voltage level indicating the rotor has reached a predetermined relative angular position.
Claim 8
Dependent Claim
94 words
A speed control system according to claim 1, wherein said controller for limiting current comprises: means for sensing current through energized motor windings; a programmable threshold comparator operable to compare the sensed current to a threshold programmed in response to the established current limit; a controlled switching device responsive to the output of said programmable threshold comparator and connected to interrupt energization of an energized motor winding when sensed current exceeds the programmed threshold, and to restore motor winding energization when sensed current falls below the programmed threshold by at least a predetermined amount.
Claim 9
Dependent Claim
30 words
A speed control system according to claim 7, wherein said controlled switching device also serves as an element of said commutation sequencer for selecting a particular motor winding for energization.
Claim 10
Independent Claim
162 words
A method for controlling the rotational velocity of an electronically commutated motor having a rotor and a plurality of stator windings selectively energized in a step-by-step sequence for effecting motor rotor rotation, stepping through the sequence occurring as the rotor reaches each of a plurality of predetermined angular positions, said method comprising: providing a series of periodic signals representative of desired rotational velocity, the periodic signals occurring at a rate proportional to desired rotational velocity with each of the periodic signals representative of a particular instantaneous desired rotor position; sensing rotor position; providing a changeable stored current limit; limiting current through energized motor windings to an established limit; said periodically comparing sensed rotor position to desired rotor position and, in the event actual rotor position leads desired rotor position by at least a predetermined amount, decreasing the established current limit, and, in the event actual rotor position lags desired rotor position by at least a predetermined amount, increasing the established current limit.
Claim 11
Independent Claim
162 words
A method for controlling the rotational velocity of an electronically commutated motor having a rotor and a plurality of stator windings selectively energized in a step-by-step sequence for effecting motor rotor rotation, stepping through the sequence occurring as the rotor reaches each of a plurality of predetermined angular positions, said method comprising: providing a series of periodic signals representative of desired rotational velocity, the periodic signals occurring at a rate proportional to desired rotational velocity with each of the periodic signals representative of a particular instantaneous desired rotor position; sensing rotor position; providing a changeable stored current limit; limiting current through energized motor windings to an established limit; said periodically comparing sensed rotor position to desired rotor position and, in the event actual rotor position leads desired rotor position by at least a predetermined amount, decreasing the established current limit, and, in the event actual rotor position lags desired rotor position by at least a predetermined amount, increasing the established current limit.
Claim 12
Dependent Claim
27 words
A method according to claim 9, which further comprises varying the occurrence rate of the series of periodic signals such that motor rotational velocity is correspondingly varied.
Claim 13
Dependent Claim
79 words
A method according to claim 9, wherein: the step of sensing rotor position includes providing a signal when the rotor reaches a predetermined angular position; and wherein the step of periodically comparing sensed rotor position to desired rotor position comprises comparing the time of occurrence of the signal indicating the rotor has reached a predetermined angular position with the time of occurrence of one of the series of periodic signals each representative of a particular instantaneous desired rotor position.
Claim 14
Dependent Claim
63 words
A method according to claim 11, wherein the step of sensing rotor position includes: integrating, with respect to time from a initial state, sampled voltage induced in a motor winding not currently energized, thereby to develop a voltage integral; and comparing the voltage integral to a predetermined reference voltage level which is indicative of a predetermined relative angular position of the motor rotor.
References Cited (Backward Citations)
US3152462A
Cited
US3152463A
Cited
US3503228A
Cited
US3279223A
Cited
US3369381A
Cited
US3754175A
Cited
US3783357A
Cited
US3783359A
Cited
US3840790A
Cited
US3931556A
Cited
US3949283A
Cited
US3911339A
Cited
US3932793A
Cited
US3979651A
Cited
US4088932A
Cited
US4119895A
Cited
US4107594A
Cited
US4107595A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-02-10 | 1984-08-11 | 1985-02-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-10 | 1988-08-11 | 1989-02-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-10 | 1992-08-11 | 1993-02-10 | $7700.00 | Window Closed / Lapsed |