US3883785A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low speed phaselock speed control system
Assignee: National Aeronautics and Space Administration
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Filing: 1973-09-27
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Granted: 1975-05-13
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Expires: 1993-09-27
Abstract
Abstract A motor speed control system for an electronically commutated brushless D.C. motor is provided which includes a phaselock loop with bi-directional torque control for locking the frequency output of a high density encoder, responsive to actual speed conditions, to a reference frequency signal, corresponding to the desired speed. The system includes a phase comparator, which produces an output in accordance with the difference in phase between the reference and encoder frequency signals, and an integrator-digital-to-analog converter unit, which converts the comparator output into an analog error signal voltage. Compensation circuitry, including a biasing means therein, is provided to convert the analog error signal voltage to a bidirectional error signal voltage which is utilized by an absolute value amplifier, rotational decoder, power amplifier-commutators, and an arrangement of commutation circuitry, forming an integral part of the phaselock loop and including position decoders, switches, and rotor position sensors, all cooperating to control the acceleration and deceleration of the motor to achieve symmetrical bi-directional torque control thereof. The phase comparator and integrator-digital-to-analog converter unit cooperate with a simplified overspeed control circuit to derive a signal which is utilized in the system to get the motor at its desired speed and to thereafter maintain it at that speed.
Inventors
- 👤 Robert W Fulcher
- 👤 John Sudey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:52
CPC Classifications
H; H02; H02P; H02P6/00; H02P6/06; H02P23/00; H02P23/18; H02P23/186
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
162 words
In combination, a brushless D.C. motor and motor speed control system for controlling the speed of said motor, said system comprising: means for generating a reference frequency signal; sensor means responsive to the motor for producing angular position signals and including an output signal having a frequency in accordance with the speed of the motor; phase comparator means for comparing the reference frequency signal with the sensor output signal and for producing an output pulse train in which each pulse thereof is determined in accordance with the difference in frequency and phase between the reference frequency signal and the sensor output signal; integrator-digital-to-analog converter means for converting the output of said phase comparator into an analog error signal voltage, biasing means for converting said analog error signal voltage to a bi-directional error signal voltages; and means responsive to the bi-directional error signal voltage of said biasing means for controlling acceleration or deceleration of said motor to achieve symmetrical bi-directional torque control thereof.
Claim 2
Dependent Claim
162 words
In combination, a brushless D.C. motor and motor speed control system for controlling the speed of said motor, said system comprising: means for generating a reference frequency signal; sensor means responsive to the motor for producing angular position signals and including an output signal having a frequency in accordance with the speed of the motor; phase comparator means for comparing the reference frequency signal with the sensor output signal and for producing an output pulse train in which each pulse thereof is determined in accordance with the difference in frequency and phase between the reference frequency signal and the sensor output signal; integrator-digital-to-analog converter means for converting the output of said phase comparator into an analog error signal voltage, biasing means for converting said analog error signal voltage to a bi-directional error signal voltages; and means responsive to the bi-directional error signal voltage of said biasing means for controlling acceleration or deceleration of said motor to achieve symmetrical bi-directional torque control thereof.
Claim 3
Dependent Claim
52 words
A combination as claimed in claim 1, wherein the last mentioned means includes an absolute value amplifier coupled to receive said bi-directional error signal voltage for producing an pair of amplitude control signals; and rotational decoder means connected to said absolute value amplifier for cooperating therewith to produce a polarity control signal.
Claim 4
Dependent Claim
107 words
A combination as claimed in claim 2, wherein the said last mentioned means further comprises position decoder means, connected to receive said angular position signals from said sensor means and said polarity control signal from said rotational decoder means, for producing an electrical signal in accordance with the position of the output shaft; a pair of amplifier means connected to receive respective ones of the pair of amplitude control signals of said absolute value amplifier and the output of said position decoder means; and switching means responsive to the output of said amplifier means for controlling the sequence and level of current flow through the motor windings.
Claim 5
Dependent Claim
76 words
A combination as claimed in claim 3, wherein said pair of amplifier means each comprise an operational amplifier having a first input connected to a respective one of the amplitude control signals of said absolute value amplifier; power commutator means connected to the output of said operational amplifier and to the output of said position decoder means; and a current feedback loop connected between said power commutator means and a second input to said operational amplifier.
Claim 6
Dependent Claim
69 words
A combination as claimed in claim 4, wherein said position decoder means includes a pair of position decoders, each having a first input connected to receive a respective angular position signal from said sensor means and a second input connected to receive the polarity control signal from said rotation decoder means, the outputs thereof being coupled to the power commutator of respective ones of said pair of amplifier means.
Claim 7
Dependent Claim
48 words
A combination as claimed in claim 1, further comprising overspeed control means resposive to the output signal of said sensor means and said reference frequency signal and having an output combined with said bi-direction error signal for preventing the speed of said motor from exceeding a predetermined value.
Claim 8
Dependent Claim
50 words
A combination As claimed in claim 1, wherein said sensor means includes position sensor means for sensing the absolute position of the output shaft of said motor for motor commutation purposes and encoder means for producing said output signal having a frequency in accordance with the speed of said 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) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |