US5103154A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Start winding switch protection circuit
Assignee: Texas Instruments Inc
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Filing: 1990-05-25
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Granted: 1992-04-07
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Expires: 2010-05-25
Abstract
Abstract A single phase, capacitor start electric motor is shown in which energization of the auxiliary winding is controlled by a triac. The triac is protected from excessive voltages caused by the vector sum of capacitor, line and induced voltages which can occur at turn-off of the triac. The triac is protected in several embodiments by a gated semiconductor switch serially connected to a current limiting or discharge resistor, both being coupled across the triac. The semiconductor switch has a voltage breakdown device connected in its gate circuit. When voltage across the triac exceeds a selected level the gated semiconductor is turned on thereby drawing sufficient current momentarily to limit the voltage across the triac to a safe level and allowing the capacitor to discharge its voltage through the auxiliary winding circuit. In another embodiment a stack of high voltage bilateral triggering devices is placed across the triac.
Inventors
- 👤 Kevin J. Dropps
- 👤 Herbert A. Thompson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:24
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/08; H03K17/081; H03K17/0814; H03K17/08144; H02; H02H; H02H9/00; H02H9/04; H02H9/045; H02H9/047; H02P; H02P1/00; H02P1/16; H02P1/42; H02P1/44
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
116 words
A single phase AC induction motor comprising a main winding and an auxiliary winding both connectable to an AC power source, a start capacitor for providing a phase shifted field, auxiliary winding switch means for connecting and disconnecting the start capacitor and auxiliary winding to and from the AC source, auxiliary winding switch protection means including a gated semiconductor switch serially connected to a discharge resistor coupled across the auxiliary winding switch and a voltage breakdown device connected to the semiconductor switch and connected to be directly responsive to the voltage across the auxiliary winding switch, the breakdown device selected to breakdown at a voltage level to prevent excessive voltage appearing across the auxiliary winding switch.
Claim 2
Dependent Claim
116 words
A single phase AC induction motor comprising a main winding and an auxiliary winding both connectable to an AC power source, a start capacitor for providing a phase shifted field, auxiliary winding switch means for connecting and disconnecting the start capacitor and auxiliary winding to and from the AC source, auxiliary winding switch protection means including a gated semiconductor switch serially connected to a discharge resistor coupled across the auxiliary winding switch and a voltage breakdown device connected to the semiconductor switch and connected to be directly responsive to the voltage across the auxiliary winding switch, the breakdown device selected to breakdown at a voltage level to prevent excessive voltage appearing across the auxiliary winding switch.
Claim 3
Dependent Claim
19 words
A single phase AC induction motor according to claim 1 in which the auxiliary winding switch is a triac.
Claim 4
Dependent Claim
19 words
A single phase AC induction motor according to claim 2 in which the gated semiconductor switch is a triac.
Claim 5
Dependent Claim
29 words
A single phase AC induction motor according to claim 3 in which the breakdown device comprises a plurality of serially connected sidacs selected to breakdown at approximately 700 volts.
Claim 6
Dependent Claim
32 words
A single phase AC induction motor according to claim 3 in which the breakdown device is a sidac connected to the junction between a resistor and a capacitor coupled across the triac.
Claim 7
Dependent Claim
19 words
A single phase AC induction motor according to claim 2 in which the gated semiconductor switch is an SCR.
Claim 8
Dependent Claim
30 words
A single phase AC induction motor according to claim 2 in which the breakdown device comprise a plurality of serially connected zener diodes selected to breakdown at approximately 700 volts.
Claim 9
Dependent Claim
33 words
A single phase AC induction motor according to claim 2 in which the breakdown device is a zener diode connected to the junction between a resistor and a capacitor coupled across the triac.
Claim 10
Dependent Claim
21 words
A single phase AC induction motor according to claim 1 in which the auxiliary winding switch comprises back to back SCR's.
References Cited (Backward Citations)
US3609461A
Cited
US3660687A
Cited
US3740632A
Cited
US3761792A
Cited
US3777232A
Cited
US3904931A
Cited
US4196462A
Cited
US4399394A
Cited
US4719399A
Cited
US5017853A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-04-07 | 1995-10-07 | 1996-04-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-04-07 | 1999-10-07 | 2000-04-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-04-07 | 2003-10-07 | 2004-04-07 | $7700.00 | Window Closed / Lapsed |