US3794894A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gyro hunt damping circuit
Assignee: BAE Systems Aircraft Controls Inc
•
Filing: 1972-03-24
•
Granted: 1974-02-26
•
Expires: 1992-03-24
Abstract
Abstract A gyro hunt damping circuit for electrically changing the phase of the excitation current applied to a synchronous motor to slowly settle changes in the lag angle of a synchronous motor and thereby dampen motor hunting, is disclosed. The current drawn by a synchronous motor is continually sensed by a current detector circuit which provides an output signal representative of the motor current. The detector output signal is applied to a comparator circuit which serves to compare average current drawn by the motor over a long time period to instantaneous current demand over short time periods. The frequency of a square wave generator, which controls the frequency of excitation current from the AC power supply of the motor, is temporarily changed in accordance with any difference between the average and instantaneous motor current demand.
Inventors
- 👤 Leer R Van
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 18:05
CPC Classifications
H; H02; H02P; H02P25/00; H02P25/02; H02P25/022; H02P25/024
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
158 words
A control circuit for damping hunting of a synchronous motor by temporarily shifting the phase of excitation signals applied to the motor by controlling the frequency of the motor power supply in accordance with detectEd changes in motor current, the control circuit comprising: detector means for continually monitoring motor current, a detector signal representative of said motor current being provided; comparator means, connected to receive said detector signals, for continually comparing average motor current to instantaneous motor current, a comparator output signal being provided that is indicative of such comparison and the relative magnitudes of the average motor current and the instantaneous motor current; a frequency generator for controlling the frequency of a power source which supplies excitation signals to said motor; and frequency control means for altering the frequency of said frequency generator in response to said comparator output signal to have the phase of said excitation signals changed in a preselected direction to damp said hunting.
Claim 2
Dependent Claim
158 words
A control circuit for damping hunting of a synchronous motor by temporarily shifting the phase of excitation signals applied to the motor by controlling the frequency of the motor power supply in accordance with detectEd changes in motor current, the control circuit comprising: detector means for continually monitoring motor current, a detector signal representative of said motor current being provided; comparator means, connected to receive said detector signals, for continually comparing average motor current to instantaneous motor current, a comparator output signal being provided that is indicative of such comparison and the relative magnitudes of the average motor current and the instantaneous motor current; a frequency generator for controlling the frequency of a power source which supplies excitation signals to said motor; and frequency control means for altering the frequency of said frequency generator in response to said comparator output signal to have the phase of said excitation signals changed in a preselected direction to damp said hunting.
Claim 3
Dependent Claim
15 words
The control circuit defined by claim 1, said frequency generator including a square wave generator.
Claim 4
Dependent Claim
14 words
The control circuit defined by claim 1, said frequency generator including a bistable multivibrator.
Claim 5
Dependent Claim
45 words
The control circuit defined by claim 1, said frequency control means including: variable resistance means for selectively changing the magnitude of input signals applied to said frequency generator; and means responsive to said comparator output signals for changing the resistance of said variable resistance means.
Claim 6
Dependent Claim
60 words
The control circuit defined by claim 4, said variable resistance means including a resistor and voltage responsive resistance means connected in parallel with said resistor for changing the combined resistance presented by said variable resistance means, the magnitude of input signals to said frequency generator being changed in accordance with said changes in the resistance of said variable resistance means.
Claim 7
Dependent Claim
38 words
The control circuit defined by claim 1, said detector means including a transformer having a primary coil that is to be connected in series between a synchronous motor to be controlled and the power source for said motor.
Claim 8
Dependent Claim
78 words
The control circuit defined by claim 1, said comparator means including: first and second channels each receiving said detector signal, said first channel having means for averaging said detector signal over a time period to provide an indication of average motor current, said second channel having means responsive to said detector signal for providing an indication of instantaneous motor current; and means for summing the outputs of said first and second channels to provide said comparator output signals.
Claim 9
Dependent Claim
46 words
The control circuit defined by claim 7, said first and second channels each including means for limiting the flow of current through said channels to alternate half cycles of said detector signal, current flow in said first and second channels being permitted in different half cycles.
Claim 10
Dependent Claim
35 words
The control circuit defined by claim 8, said first and second channels each including means for providing the respective channels with a selected RC time constant, the first channel having the longer RC time constant.
Claim 11
Dependent Claim
45 words
The control circuit defined by claim 9, said frequency control means including: variable resistance means for selectively changing the magnitude of input signals applied to said frequency generator; and means responsive to said comparator output signals for changing the resistance of said variable resistance means.
Claim 12
Dependent Claim
60 words
The control circuit defined by claim 10, said variable resistance means including a resistor and voltage responsive resistance means connected in parallel with said resistor for changing the combined resistance presented by said variable resistance means, the magnitude of input signals to said frequency generator being changed in accordance with said changes in the resistance of said variable resistance means.
Claim 13
Dependent Claim
15 words
The control circuit defined by claim 11, said frequency generator including a square wave generator.
Claim 14
Dependent Claim
38 words
The control circuit defined by claim 12, said detector meAns including a transformer having a primary coil that is to be connected in series between a synchronous motor to be controlled and the power source to said motor.
Claim 15
Dependent Claim
16 words
The control circuit defined by claim 1 wherein said synchronous motor is a gyro spin motor.
Claim 16
Dependent Claim
16 words
The control circuit defined by claim 13 wherein said synchronous motor is a gyro spin motor.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-25 | 1977-08-27 | 1978-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-25 | 1981-08-27 | 1982-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-25 | 1985-08-27 | 1986-02-26 | $7700.00 | Window Closed / Lapsed |