US3723840A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for motor current minimization
Assignee: POWER CONTROL CORP
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Filing: 1972-01-21
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Granted: 1973-03-27
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Expires: 1992-01-21
Abstract
Abstract Current minimization in a motor control system is obtained through a voltage control where the amplitude of the applied voltage is increased or decreased each time measured motor current passes through a detected minimum current level.
Inventors
- 👤 K Opal
- 👤 C Kelly
- 👤 C Newcamp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:25
CPC Classifications
H; H02; H02P; H02P27/00; H02P27/04; H02P27/06; H02P27/047
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
105 words
In a motor control system wherein motor current is caused to decrease for increasing applied voltage until a minimum current point is reached and then iNcreases with increasing applied voltage thereafter, the combination comprising: first and second directional sample and hold means for detecting minimum current conditions during periods of increasing and decreasing input voltages; first and second gated pulse means for producing trigger pulses when the current rises above said minimum current point during periods of increasing and decreasing voltages; and voltage level varying means responsive to said trigger pulses for changing the direction of voltage variation each time a trigger pulse is received.
Claim 2
Dependent Claim
105 words
In a motor control system wherein motor current is caused to decrease for increasing applied voltage until a minimum current point is reached and then iNcreases with increasing applied voltage thereafter, the combination comprising: first and second directional sample and hold means for detecting minimum current conditions during periods of increasing and decreasing input voltages; first and second gated pulse means for producing trigger pulses when the current rises above said minimum current point during periods of increasing and decreasing voltages; and voltage level varying means responsive to said trigger pulses for changing the direction of voltage variation each time a trigger pulse is received.
Claim 3
Dependent Claim
53 words
In the system of claim 1 wherein there is included means for establishing a predetermined initial voltage in a capacitor and means for producing a switching signal to initiate current minimization, said combination including sample error pulse generating means for entering a predetermined upper current limit signal into said sample and hold means.
Claim 4
Dependent Claim
24 words
The combination of claim 2 wherein trigger pulses are produced to reverse voltage direction when the motor current reaches an initial upper current value.
Claim 5
Independent Claim
81 words
The method of varying voltage in a motor control system to minimize motor current comprising: decreasing voltage until motor current crosses either a minimum, or maximum error level while current is increasing; increasing voltage until motor current crosses either a minimum, or maximum error level with current again increasing; and maintaining steady-state current minimization by reversing the direction of voltage variation each time motor current decreases to a minimum and then rises slightly above said minimum by a maximum error value.
Claim 6
Independent Claim
81 words
The method of varying voltage in a motor control system to minimize motor current comprising: decreasing voltage until motor current crosses either a minimum, or maximum error level while current is increasing; increasing voltage until motor current crosses either a minimum, or maximum error level with current again increasing; and maintaining steady-state current minimization by reversing the direction of voltage variation each time motor current decreases to a minimum and then rises slightly above said minimum by a maximum error value.
Claim 7
Independent Claim
154 words
A method for maintaining steady-state current minimization in a motor control system comprising: establishing four control modes for the conditions of: (0) voltage and current decreasing; (1) voltage decreasing with increasing current; (2) voltage increasing with decreasing current; and (3) voltage and current both increasing; operating a first circuit to hold a signal representing minimum current and a second circuit to follow current to the minimum during mode (0); comparing a signal representing motor current with the signal held by said second circuit during mode (1) and switching to mode (2) when motor current exceeds the minimum current held by said second circuit; operating said first circuit to follow motor current to said minimum and said second circuit to hold the previously sampled minimum current during mode (2) and comparing the signal of said first circuit with said motor current representation to switch to mode (0) when motor current exceeds the minimum current representation.
Claim 8
Independent Claim
154 words
A method for maintaining steady-state current minimization in a motor control system comprising: establishing four control modes for the conditions of: (0) voltage and current decreasing; (1) voltage decreasing with increasing current; (2) voltage increasing with decreasing current; and (3) voltage and current both increasing; operating a first circuit to hold a signal representing minimum current and a second circuit to follow current to the minimum during mode (0); comparing a signal representing motor current with the signal held by said second circuit during mode (1) and switching to mode (2) when motor current exceeds the minimum current held by said second circuit; operating said first circuit to follow motor current to said minimum and said second circuit to hold the previously sampled minimum current during mode (2) and comparing the signal of said first circuit with said motor current representation to switch to mode (0) when motor current exceeds the minimum current representation.
Claim 9
Dependent Claim
180 words
In a system wherein an output signal is caused to vary in response to a control signal such that the derivative of the output signal with respect to the control signal changes sign as the control signal crosses a certain level, a method for automatically varying said control signal to cause the output signal to assume a minimum level where the derivative of said output signal is substantially zero, said method comprising sampling the level of said output signal as its derivative decreases during periods of increasing control signal and holding the zero derivative level of said output signal during periods of decreasing control signal to produce a first sample and hold sample; sampling the level of said output signal as its derivative decreases during periods of decreasing control signal and holding the zero derivative level of said output signal during period of increasing output signal to produce a second sample and hold signal; and changing the direction of control signal variation each time the output signal to level crosses the level of either of said sample and hold signals.
Claim 10
Dependent Claim
180 words
In a system wherein an output signal is caused to vary in response to a control signal such that the derivative of the output signal with respect to the control signal changes sign as the control signal crosses a certain level, a method for automatically varying said control signal to cause the output signal to assume a minimum level where the derivative of said output signal is substantially zero, said method comprising sampling the level of said output signal as its derivative decreases during periods of increasing control signal and holding the zero derivative level of said output signal during periods of decreasing control signal to produce a first sample and hold sample; sampling the level of said output signal as its derivative decreases during periods of decreasing control signal and holding the zero derivative level of said output signal during period of increasing output signal to produce a second sample and hold signal; and changing the direction of control signal variation each time the output signal to level crosses the level of either of said sample and hold signals.
Claim 11
Dependent Claim
18 words
The method of claim 6 wherein said output signal is motor current and said control signal is voltage.
Claim 12
Dependent Claim
31 words
The method of claim 7 wherein first and second trigger pulses are generated when the current level sampled crosses the level of said first and second sample and hold signals, respectively.
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) | 1976-03-26 | 1976-09-25 | 1977-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-26 | 1980-09-25 | 1981-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-26 | 1984-09-25 | 1985-03-27 | $7700.00 | Window Closed / Lapsed |