US5737163A
Expired / Lapsed
US
⏱️ 0.0 years remaining
DC-AC converter protection
Assignee: Texas Instruments Tucson Corp
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Filing: 1996-06-17
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Granted: 1998-04-07
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Expires: 2016-06-17
Abstract
Abstract A method and apparatus for protecting a DC-AC converter having a transformer. According to one embodiment, an oscillator generates a periodic signal having a frequency. A switch switches an input voltage across a first winding of the transformer in accordance with the periodic signal. A watchdog device disables the switch if the frequency falls below a threshold frequency.
Inventors
- 👤 Trevor Newlin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:33
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/10; H02H7/12; H02H7/122; H02H7/1225
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
116 words
An apparatus for protecting a DC-AC converter having a transformer, the apparatus comprising: (a) an oscillator means for generating a periodic signal having a frequency; (b) a switching means for switching an input voltage across a first winding of the transformer in accordance with the periodic signal; and (c) a watchdog means for disabling the switching means if the frequency falls below a threshold frequency, the watchdog means comprising: (1) a frequency to voltage converter means for converting the frequency to a voltage; (2) a comparator means for comparing the voltage to a reference voltage corresponding to the threshold frequency; and (3) means for disabling the switching means if the voltage rises above the threshold voltage.
Claim 2
Independent Claim
116 words
An apparatus for protecting a DC-AC converter having a transformer, the apparatus comprising: (a) an oscillator means for generating a periodic signal having a frequency; (b) a switching means for switching an input voltage across a first winding of the transformer in accordance with the periodic signal; and (c) a watchdog means for disabling the switching means if the frequency falls below a threshold frequency, the watchdog means comprising: (1) a frequency to voltage converter means for converting the frequency to a voltage; (2) a comparator means for comparing the voltage to a reference voltage corresponding to the threshold frequency; and (3) means for disabling the switching means if the voltage rises above the threshold voltage.
Claim 3
Dependent Claim
59 words
The apparatus of claim 1, wherein means (c)(1) comprises a timing capacitor, a current source coupled to the timing capacitor for charging the timing capacitor, and discharge means coupled between the periodic signal of the oscillator means and the timing capacitor for discharging the timing capacitor when a transition of the periodic signal is received by the discharge means.
Claim 4
Dependent Claim
26 words
The apparatus of claim 1, wherein means (c) further comprises (4) means for enabling the switching means if the frequency rises above a second threshold frequency.
Claim 5
Dependent Claim
31 words
The apparatus of claim 3, wherein means (c)(4) comprises means for enabling the switching means if the frequency rises above the second threshold frequency for more than a time out period.
Claim 6
Dependent Claim
16 words
The apparatus of claim 4, wherein the threshold frequency is equal to the second threshold frequency.
Claim 7
Dependent Claim
39 words
The apparatus of claim 1, wherein means (b) switches the input voltage across the first winding of the transformer in accordance with the periodic signal to provide an output square wave voltage across a second winding of the transformer.
Claim 8
Dependent Claim
50 words
The apparatus of claim 1, wherein: the switching means comprises at least one switching transistor having an output coupled to the first winding of the transformer; and means (c) comprises means for tristating the output of the at least one switching transistor if the frequency falls below the threshold frequency.
Claim 9
Independent Claim
112 words
A method for protecting a DC-AC converter having a transformer, the method comprising the steps of: (a) generating with an oscillator means a periodic signal having a frequency; (b) switching with a switching means an input voltage across a first winding of the transformer in accordance with the periodic signal; and (c) disabling the switching means if the frequency falls below a threshold frequency, wherein step (c) comprises the steps of: (1) converting the frequency to a voltage with a frequency to voltage converter means; (2) comparing the voltage to a reference voltage corresponding to the threshold frequency; and (3) disabling the switching means if the voltage rises above the threshold voltage.
Claim 10
Independent Claim
112 words
A method for protecting a DC-AC converter having a transformer, the method comprising the steps of: (a) generating with an oscillator means a periodic signal having a frequency; (b) switching with a switching means an input voltage across a first winding of the transformer in accordance with the periodic signal; and (c) disabling the switching means if the frequency falls below a threshold frequency, wherein step (c) comprises the steps of: (1) converting the frequency to a voltage with a frequency to voltage converter means; (2) comparing the voltage to a reference voltage corresponding to the threshold frequency; and (3) disabling the switching means if the voltage rises above the threshold voltage.
Claim 11
Dependent Claim
63 words
The apparatus of claim 8, wherein the frequency to voltage converter means comprises a timing capacitor, a current source coupled to the timing capacitor for charging the timing capacitor, and discharge means coupled between the periodic signal of the oscillator means and the timing capacitor for discharging the timing capacitor when a transition of the periodic signal is received by the discharge means.
Claim 12
Dependent Claim
24 words
The method of claim 8, further comprising the step of: (d) enabling the switching means if the frequency rises above a second threshold frequency.
Claim 13
Dependent Claim
32 words
The method of claim 10, wherein step (d) comprises the step of enabling the switching means if the frequency rises above the second threshold frequency for more than a time out period.
Claim 14
Dependent Claim
16 words
The method of claim 11, wherein the threshold frequency is equal to the second threshold frequency.
Claim 15
Dependent Claim
43 words
The method of claim 8, wherein step (b) comprises the step of switching the input voltage across the first winding of the transformer in accordance with the periodic signal to provide an output square wave voltage across a second winding of the transformer.
Claim 16
Dependent Claim
51 words
The method of claim 8, wherein: the switching means comprises at least one switching transistor having an output coupled to the first winding of the transformer; and step (c) comprises the step of tristating the output of the at least one switching transistor if the frequency falls below the threshold frequency.
Claim 17
Independent Claim
119 words
An apparatus for protecting a DC-AC converter having a transformer, an oscillator means for generating a periodic signal having a frequency, and a switching means for switching an input voltage across a first winding of the transformer in accordance with the periodic signal, the apparatus comprising: (a) means for monitoring the frequency; and (b) means for disabling the switching means if the frequency falls below a threshold frequency, wherein means (b) comprises: (1) a frequency to voltage converter means for converting the frequency to a voltage; (2) a comparator means for comparing the voltage to a reference voltage corresponding to the threshold frequency; and (3) means for disabling the switching means if the voltage rises above the threshold voltage.
Claim 18
Independent Claim
119 words
An apparatus for protecting a DC-AC converter having a transformer, an oscillator means for generating a periodic signal having a frequency, and a switching means for switching an input voltage across a first winding of the transformer in accordance with the periodic signal, the apparatus comprising: (a) means for monitoring the frequency; and (b) means for disabling the switching means if the frequency falls below a threshold frequency, wherein means (b) comprises: (1) a frequency to voltage converter means for converting the frequency to a voltage; (2) a comparator means for comparing the voltage to a reference voltage corresponding to the threshold frequency; and (3) means for disabling the switching means if the voltage rises above the threshold voltage.
Claim 19
Dependent Claim
59 words
The apparatus of claim 15, wherein means (b)(1) comprises a timing capacitor, a current source coupled to the timing capacitor for charging the timing capacitor, and discharge means coupled between the periodic signal of the oscillator means and the timing capacitor for discharging the timing capacitor when a transition of the periodic signal is received by the discharge means.
Claim 20
Dependent Claim
23 words
The apparatus of claim 15, further comprising: (c) means for enabling the switching means if the frequency rises above a second threshold frequency.
Claim 21
Dependent Claim
31 words
The apparatus of claim 17, wherein means (c) comprises means for enabling the switching means if the frequency rises above the second threshold frequency for more than a time out period.
Claim 22
Dependent Claim
16 words
The apparatus of claim 18, wherein the threshold frequency is equal to the second threshold frequency.
Claim 23
Dependent Claim
40 words
The apparatus of claim 15, wherein the switching means switches the input voltage across the first winding of the transformer in accordance with the periodic signal to provide an output square wave voltage across a second winding of the transformer.
Claim 24
Dependent Claim
50 words
The apparatus of claim 15, wherein: the switching means comprises at least one switching transistor having an output coupled to the first winding of the transformer; and means (b) comprises means for tristating the output of the at least one switching transistor if the frequency falls below the threshold frequency.
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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) | 2001-04-06 | 2001-10-06 | 2002-04-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-04-06 | 2005-10-06 | 2006-04-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-04-06 | 2009-10-06 | 2010-04-07 | $7700.00 | Window Closed / Lapsed |