US5349515A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Switch mode power supply with feed-forward pulse limit control
Assignee: RCA Licensing Corp
•
Filing: 1993-07-23
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Granted: 1994-09-20
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Expires: 2013-07-23
Abstract
Abstract In a switch mode power supply, a full wave rectified AC mains supply voltage is produced from an AC mains supply voltage without low-pass filtering. The unfiltered rectified voltage is applied to a winding of a flyback transformer that is coupled to a switching transistor. A first plurality of current pulses are generated in the winding from the rectified voltage at a frequency that is higher than the frequency of the mains supply voltage and at peak amplitudes that vary in a manner to reduce a power factor. A second supply voltage is applied via a second switching transistor to the winding to produce in the winding a second plurality of current pulses that reduce a ripple component at an output of the power supply. The second plurality of current pulses are pulse-width modulated in a feed-forward manner during a period of the mains supply voltage in accordance with the mains supply voltage. An overload threshold point is also shifted to a higher value remotely from the peak of the mains voltage, in a feed-forward manner. This results in the power factor being less affected by load variations.
Inventors
- 👤 Magdy Megeid
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 16:44
CPC Classifications
H; H02; H02M; H02M1/00; H02M1/42; H02M1/4208; H02M1/4258; H02M3/00; H02M3/22; H02M3/24; H02M3/28; H02M3/325; H02M3/335; H02M3/33507; H02M3/33523; H02M3/33569; H04; H04N; H04N5/00; H04N5/63; H02M1/0003; H02M1/0016; H02M1/0022; H02M1/0032; Y; Y02; Y02B; Y02B70/00; Y02B70/10
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
193 words
A switch mode power supply, comprising: a source of an AC, mains supply voltage; an inductance; a first rectifier coupled to said mains source for rectifying said mains supply voltage to apply to said inductance a rectified, first supply voltage; switching means responsive to a switching signal for generating in said inductance pulse-width modulated current pulses from said first supply voltage at a frequency that is substantially higher than a frequency of said mains supply voltage, said current pulses being coupled from said inductance to a load circuit to energize said load circuit; a pulse-width modulator responsive to a feedback signal for generating said switching signal in accordance with said feedback signal; and means coupled to said pulse-width modulator and responsive to said mains supply voltage for limiting a pulse-width of said switching signal such that a limit associated with said pulse-width varies during a period of said mains supply voltage in accordance with a waveform of said mains supply voltage and such that when said pulse-width reaches said limit, a further change in said feedback signal is prevented from further changing said pulse-width in a direction that tends to exceed said limit.
Claim 2
Dependent Claim
193 words
A switch mode power supply, comprising: a source of an AC, mains supply voltage; an inductance; a first rectifier coupled to said mains source for rectifying said mains supply voltage to apply to said inductance a rectified, first supply voltage; switching means responsive to a switching signal for generating in said inductance pulse-width modulated current pulses from said first supply voltage at a frequency that is substantially higher than a frequency of said mains supply voltage, said current pulses being coupled from said inductance to a load circuit to energize said load circuit; a pulse-width modulator responsive to a feedback signal for generating said switching signal in accordance with said feedback signal; and means coupled to said pulse-width modulator and responsive to said mains supply voltage for limiting a pulse-width of said switching signal such that a limit associated with said pulse-width varies during a period of said mains supply voltage in accordance with a waveform of said mains supply voltage and such that when said pulse-width reaches said limit, a further change in said feedback signal is prevented from further changing said pulse-width in a direction that tends to exceed said limit.
Claim 3
Dependent Claim
36 words
A power supply according to claim 1 wherein said main supply voltage is coupled to said pulse-width limiting means via a signal path that bypasses said inductance in a feed forward manner for varying said limit.
Claim 4
Dependent Claim
43 words
A power supply according to claim 1 wherein, during said period, an increase in a magnitude of said mains supply voltage causes said limit associated with a pulse width of a given current pulse of said current pulses to decrease, and vice verse.
Claim 5
Dependent Claim
24 words
A power supply according to claim 1 wherein said limit shifts to a higher value remotely from a peak of said main supply voltage.
Claim 6
Dependent Claim
43 words
A power supply according to claim 1 wherein said pulse-width modulator is responsive to said main supply voltage for modulating said switching signal in accordance with said main supply voltage in a feed-forward manner when said pulse width is smaller than said limit.
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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) | 1997-09-19 | 1998-03-21 | 1998-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-09-19 | 2002-03-21 | 2002-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-09-19 | 2006-03-21 | 2006-09-20 | $7700.00 | Window Closed / Lapsed |