Primary side control of primary resonant flyback converters
First Claim
1. A primary resonant flyback converter comprising:
- a primary winding;
a secondary winding magnetically coupled to the primary winding and electrically coupled to an output rectifier, and an output terminal;
a resonant capacitor coupled in series with the primary winding;
a main switch configured to switch on to energize the primary winding and the resonant capacitor from a DC voltage bus and to switch off to transfer energy stored in the primary winding to the secondary winding;
an auxiliary switch configured to switch on during an off time of the main switch to allow a resonant current to circulate through the primary winding and the resonant capacitor; and
a control circuit configured to operate the main switch and the auxiliary switch to produce a desired voltage at the output terminal.
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Accused Products
Abstract
A primary resonant flyback converter may include a primary winding, a resonant capacitor in series with the primary winding, a secondary winding magnetically coupled to the primary winding, and an output electrically coupled to the secondary winding. A main switch may be operated to energize the primary winding when closed and transfer energy stored in the primary winding to the secondary winding when open. An auxiliary switch may be configured to switch complimentarily to the main switch, thereby allowing a resonant current to circulate through the primary winding and capacitor. Switch timing may be controlled to produce a desired output voltage. The primary resonant flyback converter may include one or more of: (a) output voltage sensing across the resonant capacitor; (b) a full bridge switch configuration; and (c) lossless current sensing using a current sensing circuit coupled in parallel with the resonant capacitor.
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Citations
20 Claims
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1. A primary resonant flyback converter comprising:
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a primary winding; a secondary winding magnetically coupled to the primary winding and electrically coupled to an output rectifier, and an output terminal; a resonant capacitor coupled in series with the primary winding; a main switch configured to switch on to energize the primary winding and the resonant capacitor from a DC voltage bus and to switch off to transfer energy stored in the primary winding to the secondary winding; an auxiliary switch configured to switch on during an off time of the main switch to allow a resonant current to circulate through the primary winding and the resonant capacitor; and a control circuit configured to operate the main switch and the auxiliary switch to produce a desired voltage at the output terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A primary resonant flyback converter comprising:
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a primary winding; a secondary winding magnetically coupled to the primary winding and electrically coupled to a rectifier, and an output terminal; a resonant capacitor coupled in series with the primary winding; a main switch configured to switch on to energize the primary winding and the resonant capacitor from a DC voltage bus; an auxiliary switch configured to switch on during an off time of the main switch to allow a resonant current to circulate through the primary winding and the resonant capacitor; and a control circuit configured to operate the main switch and the auxiliary switch responsive to a sensed output voltage and further configured to sense a current through the primary coil using a current sense circuit coupled in parallel with the resonant capacitor, the current sense circuit comprising a sense capacitor and at least one sense resistor. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method of operating a primary resonant flyback converter, the method comprising:
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switching a main switch responsive to a sensed output voltage, wherein closing the main switch energizes a primary coil coupled in series with a resonant capacitor and opening the main switch transfers energy stored in the primary coil to a load electrically connected to a secondary coil magnetically coupled to the primary coil; and switching an auxiliary switch complimentarily to the main switch, wherein closing the auxiliary switch allows a resonant current to circulate through the primary coil and the resonant capacitor; wherein the sensed output voltage is a voltage across the resonant capacitor. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification