US3764869A
Expired / Lapsed
US
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Method and apparatus for pulse width control for brushless dc motors
Assignee: Standard Research Institute
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Filing: 1973-02-26
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Granted: 1973-10-09
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Expires: 1993-02-26
Abstract
Abstract A method and system for deriving drive pulses for brushless DC motors. Periodic shaft position signals are developed, one for each of the motor phases. A plurality of pulse width derivation means are provided, one for each of the motor phases. Each pulse width derivation means combines and rectifies the shaft position signals for all the motor phases other than the one phase for which the pulse is being derived to form a rectified signal. In accordance with one embodiment, comparator means are provided for comparing a control signal which can be a speed error signal to the rectified signal to form a drive pulse for the one phase. In other embodiments a periodic function having its period related to the period of the shaft position signals is added to the control signal to form a composite signal which is then compared to the rectified signal to develop drive pulses for the one phase.
Inventors
- 👤 J Woodbury
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:43
CPC Classifications
H; H02; H02P; H02P6/00; H02P6/06
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
176 words
In a control circuit for a brushless motor of the type having a plurality of phases and where it is desired to accurately control the motor speed by comparison to a motor speed reference signal over a variety of load conditions, a shaft position encoder for developing a plurality of periodic shaft position signals, one for each of the plurality of motor phases, motor speed sensing means for developing a signal proportional to actual motor speed, means for comparing the actual motor speed signal to the motor speed reference signal to generate a speed error signal proportional to the variation therebetween, a plurality of pulse width derivation means, one for each of the motor phases, each of said pulse width derivation means comprising means for combining and rectifying the shaft position signals for all the motor phases other than the one phase for which the pulse is being derived to form a rectified signal, and comparator means for comparing said speed error signal to said rectified signal to form a drive pulse for the one phase.
Claim 2
Dependent Claim
176 words
In a control circuit for a brushless motor of the type having a plurality of phases and where it is desired to accurately control the motor speed by comparison to a motor speed reference signal over a variety of load conditions, a shaft position encoder for developing a plurality of periodic shaft position signals, one for each of the plurality of motor phases, motor speed sensing means for developing a signal proportional to actual motor speed, means for comparing the actual motor speed signal to the motor speed reference signal to generate a speed error signal proportional to the variation therebetween, a plurality of pulse width derivation means, one for each of the motor phases, each of said pulse width derivation means comprising means for combining and rectifying the shaft position signals for all the motor phases other than the one phase for which the pulse is being derived to form a rectified signal, and comparator means for comparing said speed error signal to said rectified signal to form a drive pulse for the one phase.
Claim 3
Independent Claim
150 words
A method of deriving drive pulses for a brushless motor of the type having a plurality of phases and where it is desired to accurately control the motor speed by comparison to a motor speed reference signal over a variety of load conditions comprising the steps of generating a plurality of periodic shaft position signals, one for each of the plurality of motor phases, generating a signal proportional to actual motor speed, comparing the actual motor speed signal to the motor speed reference signal to generate a speed error signal, rectifying and combining the shaft position signals for all the motor phases other than the one phase for which the pulse is being derived to form a rectified signal, and comparing the speed error signal to the rectified signal whereby a drive pulse is applied to the one phase whenever the speed error signal is greater than the rectified signal.
Claim 4
Independent Claim
150 words
A method of deriving drive pulses for a brushless motor of the type having a plurality of phases and where it is desired to accurately control the motor speed by comparison to a motor speed reference signal over a variety of load conditions comprising the steps of generating a plurality of periodic shaft position signals, one for each of the plurality of motor phases, generating a signal proportional to actual motor speed, comparing the actual motor speed signal to the motor speed reference signal to generate a speed error signal, rectifying and combining the shaft position signals for all the motor phases other than the one phase for which the pulse is being derived to form a rectified signal, and comparing the speed error signal to the rectified signal whereby a drive pulse is applied to the one phase whenever the speed error signal is greater than the rectified signal.
Claim 5
Dependent Claim
215 words
In a control circuit for a brushless motor of the type having a plurality of phases and where it is desired to accurately control the motor speed by comparison to a motor speed reference signal over a variety of load conditions, a shaft position encoder for developing a plurality of periodic shaft position signals, one for each of the plurality of motor phases, motor speed sensing means for developing a signal proportional to actual motor speed, function generating means for generating a periodic function having a frequency related to the frequency of the periodic shaft position signal, means for comparing the actual motor speed signal to the motor speed reference signal to generate a speed error signal representative of the variation therebetween, adder means for combining the speed error signal with said periodic function to form a composite feedback signal, a plurality of pulse width derivation means, one for each of the motor phases, each of said pulse width derivation means comprising means for rectifying and combining the shaft position signals for all the motor phases other than the one phase for which the pulse is being derived to form a rectified signal, and comparator means for comparing said composite feedback signal to said rectified signal to form a drive pulse for the one phase.
Claim 6
Dependent Claim
215 words
In a control circuit for a brushless motor of the type having a plurality of phases and where it is desired to accurately control the motor speed by comparison to a motor speed reference signal over a variety of load conditions, a shaft position encoder for developing a plurality of periodic shaft position signals, one for each of the plurality of motor phases, motor speed sensing means for developing a signal proportional to actual motor speed, function generating means for generating a periodic function having a frequency related to the frequency of the periodic shaft position signal, means for comparing the actual motor speed signal to the motor speed reference signal to generate a speed error signal representative of the variation therebetween, adder means for combining the speed error signal with said periodic function to form a composite feedback signal, a plurality of pulse width derivation means, one for each of the motor phases, each of said pulse width derivation means comprising means for rectifying and combining the shaft position signals for all the motor phases other than the one phase for which the pulse is being derived to form a rectified signal, and comparator means for comparing said composite feedback signal to said rectified signal to form a drive pulse for the one phase.
Claim 7
Dependent Claim
17 words
A control circuit in accordance with claim 3 in which said periodic function is a sinusoidal function.
Claim 8
Dependent Claim
26 words
A control circuit in accordance with claim 3 in which said shaft position encoder develops a plurality of periodic shaft position signals which are sinusoidal functions.
Claim 9
Dependent Claim
118 words
In a control circuit for a brushless motor of the type having a plurality of phases, a shaft position encoder for developing a plurality of periodic shaft position signals, one for each of the plurality of motor phases, means for generating a composite signal, a plurality of pulse width derivation means, one for each of the motor phases, each of said pulse width derivation means comprising means for combining and rectifying the shaft position signals for all the motor phases other than the one phase for which the pulse is being derived to form a rectified signal, and comparator means for comparing said composite signal to said rectified signal to form a drive pulse for the one phase.
Claim 10
Dependent Claim
118 words
In a control circuit for a brushless motor of the type having a plurality of phases, a shaft position encoder for developing a plurality of periodic shaft position signals, one for each of the plurality of motor phases, means for generating a composite signal, a plurality of pulse width derivation means, one for each of the motor phases, each of said pulse width derivation means comprising means for combining and rectifying the shaft position signals for all the motor phases other than the one phase for which the pulse is being derived to form a rectified signal, and comparator means for comparing said composite signal to said rectified signal to form a drive pulse for the one phase.
Claim 11
Dependent Claim
47 words
A control circuit in accordance with claim 6 wherein said means for generating a composite signal generates a composite signal which is the sum of a control signal and a periodic signal, the periodic signal being related in frequency to the frequency of the shaft position signal.
Claim 12
Dependent Claim
18 words
A control circuit in accordance with claim 6 wherein the plurality of periodic shaft position signals are sinusoidal.
Claim 13
Dependent Claim
16 words
A control circuit in accordance with claim 7 wherein said periodic signal is a sinusoidal signal.
References Cited (Backward Citations)
US3483457A
Cited
US3696277A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-08 | 1977-04-09 | 1977-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-08 | 1981-04-09 | 1981-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-08 | 1985-04-09 | 1985-10-09 | $7700.00 | Window Closed / Lapsed |