US3781614A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Induction motor control system
Assignee: Westinghouse Air Brake Co
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Filing: 1972-07-31
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Granted: 1973-12-25
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Expires: 1992-07-31
Abstract
Abstract This invention covers an auxiliary control system for automatically changing the operating point of an a. c. induction motor independent of normal control thereof in order to counteract voltage deviations either above or below a preselected range in which supply voltage to the input of a solid state inverter device controlling the motor must be maintained in order to prevent inadvertent system shutdown or damage. The motor operating point is moved toward a condition of motoring or regeneration, in accordance with the voltage deviation being of increasing or decreasing character, respectively, in order to adjust the level of power demanded by the motor and thereby counteract the voltage deviation until the inverter input voltage is restored to the desired level. The system is particularly useful in permitting the kinetic energy of a moving body, such as a railway vehicle, to provide regenerative voltage for maintaining inverter input voltage during periods of power interruption, such as occur in traversing line gaps.
Inventors
- 👤 B Mokrytzki
- 👤 P Hammond
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 04:35
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/08; H02H7/09; B; B60; B60L; B60L9/00; B60L9/16; B60L9/18; B60L9/22; H02H7/0833; H02P; H02P1/00; H02P1/16; H02P1/26; H02P1/265; B60L2200/00; B60L2200/26; B60L2220/00; B60L2220/10; B60L2220/12
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
216 words
A system for regulating the operating point of an a. c. motor to control the power flow thereof in either a motoring or regenerative mode comprising: a. inverter means including a plurality of switching elements via which a source of d. c. voltage at the input of said inverter is interconnected with said motor; b. logic means for gating said switching elements at a rate that determines the frequency at which said inverter means is driven; c. regulator means for providing a slip control signal of variable magnitude to control the gating frequency of said logic means; and d. control means operative responsive to a voltage deviation at the input of said inverter means in excess of a predetermined amount for adjusting said slip control signal independent of said regulator means to effect a change in the operating point of said motor such as to counteract said voltage deviation, said control means being characterized by a fast response slip control network for adjusting said slip control signal to an extreme value corresponding to an operating point of said motor beyond the actual operating point at which said voltage deviation is counteracted, thereby causing said motor to reach said actual operating point at a rate exceeding a rate determined by the normal time constant to said motor.
Claim 2
Independent Claim
216 words
A system for regulating the operating point of an a. c. motor to control the power flow thereof in either a motoring or regenerative mode comprising: a. inverter means including a plurality of switching elements via which a source of d. c. voltage at the input of said inverter is interconnected with said motor; b. logic means for gating said switching elements at a rate that determines the frequency at which said inverter means is driven; c. regulator means for providing a slip control signal of variable magnitude to control the gating frequency of said logic means; and d. control means operative responsive to a voltage deviation at the input of said inverter means in excess of a predetermined amount for adjusting said slip control signal independent of said regulator means to effect a change in the operating point of said motor such as to counteract said voltage deviation, said control means being characterized by a fast response slip control network for adjusting said slip control signal to an extreme value corresponding to an operating point of said motor beyond the actual operating point at which said voltage deviation is counteracted, thereby causing said motor to reach said actual operating point at a rate exceeding a rate determined by the normal time constant to said motor.
Claim 3
Dependent Claim
63 words
The system as recited in claim 1, further characterized in that said fast response slip control network includes first amplifier means operative to concurrently reflect both a proportional and derivative term for providing an output at said fast response slip control network to effect adjustment of said slip control signal in accordance with the magnitude and rate of change of said voltage deviation.
Claim 4
Dependent Claim
62 words
The system as recited in claim 2, further characterized in that said first amplifier means is provided at its input with parallel connected resistive and capacitive means which cooperate with resistive means in the feedback path of said first amplifier means to provide said proportional and derivative terms with such gain as to adjust said slip control signal to said extreme value.
Claim 5
Dependent Claim
101 words
The system as rectied in claim 2, wherein said control means further comprises: a. a slow response slip control network including second amplifier means for producing an output at said slow response slip control network in accordance with the magnitude of said voltage deviation; and b. said fast response slip control network further including third amplifier means having a non-linear gain curve and having its output connected to the input of said first amplifier means; and c. first summing means for adjusting said slip control signal in accordance with the sum of said fast and slow response slip control network outputs.
Claim 6
Dependent Claim
78 words
The system as recited in claim 4, further characterized in that the output of said slow response slip control network is greater than the output of said fast response slip control network when said third amplifier means is operating in the low gain region of its non-linear gain curve and less than the output of said fast response slip control network when said third amplifier means is operating in the high gain region of its non-linear gain curve.
Claim 7
Dependent Claim
33 words
The system as recited in claim 4, further characterized in that said third amplifier means includes means in its feedback network for generating said non-linear gain curve in accordance with an exponential function.
Claim 8
Dependent Claim
111 words
The system as recited in claim 4, wherein said control means further comprises sensing means for providing a spillover signal proportional to the magnitude of said voltage deviation in excess of said predetermined amount, said spillover signal being connected to the inputs of said second and third amplifier means, said second amplifier means being disposed intermediate said regulator means and said first summing means with said slip control signal provided by said regulating means being connected to the input of said second amplifier means in parallel with said spillover signal for algebraic summation therewith to effect adjustment of said slip signal providing the output of said slow response slip control network.
Claim 9
Dependent Claim
69 words
The system as recited in claim 7 wherein said sensing means comprises amplifier means operative responsive to said voltage deviation exceeding a value corresponding to the upper limit of a range representing said predetermined amount for providing said spillover signal in one sense and responsive to said voltage deviation exceeding a value corres-ponding to the lower limit of said range to provide said spillover signal in the opposite sense.
Claim 10
Dependent Claim
58 words
The system as recited in claim 4, further comprising: a. speed sensing means for providing a speed signal representing the speed of said motor; and b. second summing means for providing a frequency signal to control the gating frequency of said logic means in accordance with the algebraic summation of said speed signal and said slip control signal.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-24 | 1977-06-25 | 1977-12-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-24 | 1981-06-25 | 1981-12-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-24 | 1985-06-25 | 1985-12-25 | $7700.00 | Window Closed / Lapsed |