US3787756A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Inrush current limiting circuit
Assignee: Pioneer Magnetics Inc
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Filing: 1973-01-19
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Granted: 1974-01-22
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Expires: 1993-01-19
Abstract
Abstract An inrush current limiting circuit is provided for use with transistorized high voltage power supplies to permit such power supplies to use capacitor input filters. The inrush current limiting circuit of the invention prevents the creation of a large inrush charging current to the capacitor input filter when the power supply is first energized, and which would otherwise be liable to cause damage to switches and relays in the power supply. The current limiting circuit to be described includes one or more silicon controlled rectifiers in series with the input of the filter, and it also includes a control circuit connected to the silicon controlled rectifiers and to the capacitor input filters. The control circuit serves to control the firing point of the silicon controlled rectifiers relative to successive half cycles of the rectified alternating current input when the power supply is first turned on, so as to cause the silicon controlled rectifier to fire at different points during each successive half cycle. This control serves to maintain the current flow into the filter at an acceptable level at all times.
Inventors
- 👤 J Berger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 16:40
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/02; H02M7/04; H02M7/12; H02M7/145; H02M7/155; H02M7/1555; H02M7/1557
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
191 words
In a circuit for converting alternating current to direct current and which includes a rectifying input circuit for converting an alternating current input voltage into a pulsating direct current voltage composed of a progression of unidirectional half-cycles of said alternating current input voltage, and a filter including capacitor means connected to said input circuit; an inrush current limiting circuit included in said converting circuit including: switching circuit means connected in series between said input circuit and said capacitor means; and a control circuit connected to said input circuit and to said switching circuit means for applying a trigger signal to said switching circuit means to close said switching circuit means momentarily during each half cycle of said pulsating direct current voltage and for varying the timing of said closing from a reset point in each half cycle at which a relatively low voltage is applied to said capacitor means towards a further point in each half cycle at which a relatively high voltage is applied to said capacitor means, the variation of said timing proceeding at a controlled rate as the charge on said capacitor means increases towards a predetermined value.
Claim 2
Dependent Claim
191 words
In a circuit for converting alternating current to direct current and which includes a rectifying input circuit for converting an alternating current input voltage into a pulsating direct current voltage composed of a progression of unidirectional half-cycles of said alternating current input voltage, and a filter including capacitor means connected to said input circuit; an inrush current limiting circuit included in said converting circuit including: switching circuit means connected in series between said input circuit and said capacitor means; and a control circuit connected to said input circuit and to said switching circuit means for applying a trigger signal to said switching circuit means to close said switching circuit means momentarily during each half cycle of said pulsating direct current voltage and for varying the timing of said closing from a reset point in each half cycle at which a relatively low voltage is applied to said capacitor means towards a further point in each half cycle at which a relatively high voltage is applied to said capacitor means, the variation of said timing proceeding at a controlled rate as the charge on said capacitor means increases towards a predetermined value.
Claim 3
Dependent Claim
67 words
The combination defined in claim 1, in which the half cycles of said pulsating direct current voltage each has a sinusoidal wave form extending from zero degrees to 180*, and in which said control circuit shifts said closing point from substantially 180* towards zero degrees for each successive cycle of said pulsating direct current voltage as the charge on said capacitor means increases towards said predetermined value.
Claim 4
Dependent Claim
31 words
The combination defined in claim 1, and which includes resetting circuitry in said control circuit for returning the closing point to said reset point when said capacitor means loses its charge.
Claim 5
Dependent Claim
98 words
The combination defined in claim 3, in which said resetting circuitry includes a first capacitor and a second capacitor, and circuitry connected to said first capacitor and to said second capacitor for discharging said first capacitor during each half cycle of said pulsating direct current voltage at a rate determined by the charge on said second capacitor, and circuitry connected to said second capacitor for charging said second capacitor relatively slowly as said capacitor means in the filter is charged and for discharging said second capacitor Relatively rapidly as said capacitor means in the filter loses its charge.
Claim 6
Dependent Claim
17 words
The combination defined in claim 1, in which said switching circuit means includes a silicon controlled rectifier.
Claim 7
Dependent Claim
48 words
The combination defined in claim 1, in which said switching circuit means includes a pair of silicon controlled rectifiers, and said control circuit includes circuitry connected to said silicon controlled rectifiers for triggering said silicon controlled rectifiers alternately for successive half cycles of said pulsating direct current voltage.
Claim 8
Dependent Claim
42 words
The combination defined in claim 6, in which said control circuit includes a pilot silicon controlled rectifier connected to said pair of silicon controlled rectifiers for applying a trigger signal to said pair of silicon controlled rectifiers to control the triggering thereof.
Claim 9
Dependent Claim
26 words
The combination defined in claim 1, in which said control circuit includes a network for extending the duration of said trigger signal by a predetermined amount.
Claim 10
Dependent Claim
68 words
The combination defined in claim 7, in which said control circuit includes first and second pilot silicon controlled rectifiers respectively connected to said silicon controlled rectifiers of said pair for applying respective trigger signals thereto, and said control circuit includes first and second networks connected to respective ones of said pilot silicon controlled rectifiers to extend the duration of each of said trigger signals by a predetermined amount.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-21 | 1977-07-23 | 1978-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-21 | 1981-07-23 | 1982-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-21 | 1985-07-23 | 1986-01-22 | $7700.00 | Window Closed / Lapsed |