Switched leg power supply
First Claim
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1. A power supply which operates from a switched leg and which includes a first switch for controlling the flow of current through the switched leg comprising:
- an inductor;
a capacitor coupled to the inductor;
a second switch, coupled in series with the inductor, wherein the second switch, inductor and capacitor are coupled across the first switch such that the inductor receives current from the power line only when the first switch is open and the second switch is closed; and
a control circuit coupled to the first switch and second switch for periodically switching the second switch and for (i) opening the first switch when the second switch is closed to provide current to the inductor for the condition where the first switch is closed so as to allow current to flow in the switched leg, and (ii) leaving the first switch open when the second switch is closed for the condition where the first switch is not providing current in the switched leg.
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Abstract
A power supply for operating from a switched leg of an AC power line is described. A switch provides current during the beginning of each AC half cycle to an inductor and charges a capacitor. When the switch is open, the inductor continues to charge the capacitor. During the time that the inductor is coupled to that AC line, the switched leg is open. For instance, the signal used to close the switch also prevents a triac in the switched leg from conducting.
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Citations
9 Claims
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1. A power supply which operates from a switched leg and which includes a first switch for controlling the flow of current through the switched leg comprising:
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an inductor; a capacitor coupled to the inductor; a second switch, coupled in series with the inductor, wherein the second switch, inductor and capacitor are coupled across the first switch such that the inductor receives current from the power line only when the first switch is open and the second switch is closed; and a control circuit coupled to the first switch and second switch for periodically switching the second switch and for (i) opening the first switch when the second switch is closed to provide current to the inductor for the condition where the first switch is closed so as to allow current to flow in the switched leg, and (ii) leaving the first switch open when the second switch is closed for the condition where the first switch is not providing current in the switched leg. - View Dependent Claims (2, 3, 4)
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5. A power supply for coupling to a switched leg of an alternating current AC power line which includes a first switch comprising:
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an inductor; a capacitor coupled to the inductor; a second switch coupled in series with the inductor wherein the second switch, inductor and capacitor receive current from the power line only when the first switch is open and the second switch is closed; and a control circuit coupled to the first switch and second switch for closing the second switch at a zero crossing on the power line and for (i) opening the first switch when the second switch is closed to provide current to the inductor for the condition where the first switch is closed so as to allow current to flow in the switched leg, and (ii) leaving the first switch open when the second switch is closed for the condition where the first switch is not providing current in the switched leg. - View Dependent Claims (6, 7, 8, 9)
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Specification