Circuits and methods for synchronous rectification in resonant converters
First Claim
1. A resonant converter comprising:
- a resonant converter primary stage including;
a first switch;
a second switch coupled in series with the first switch;
a controller coupled to the first switch and the second switch and programmed to control operation of the first switch and the second switch;
a first transformer comprising a primary coil coupled to a node between the first switch and the second switch; and
a resonant inductor coupled to the primary coil of the first transformer;
a resonant converter secondary stage including;
a second transformer comprising;
a primary coil coupled to the resonant inductor; and
a secondary coil comprising a first coil section and a second coil section coupled to the first coil section;
a third switch coupled to the first coil section of the secondary coil of the second transformer; and
a fourth switch coupled to the second coil section of the secondary coil of the second transformer; and
a switch drive circuit configured to drive the third switch and the fourth switch for synchronous rectification, wherein the switch drive circuit comprises a secondary coil of the first transformer.
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Accused Products
Abstract
A resonant converter includes a primary stage having first and second switches coupled in series, a controller coupled to the first switch and the second switch to control operation thereof, a first transformer comprising a primary coil coupled to a node between the first and second switches, and a resonant inductor coupled to the primary coil of the first transformer. The resonant converter also includes a secondary stage having a second transformer formed of a primary coil coupled to the resonant inductor and a secondary coil comprising first and second coil sections, a third switch coupled to the first coil section of the secondary coil, and a fourth switch coupled to the second coil section of the secondary coil. A switch drive circuit is provided to drive the third and fourth switches for synchronous rectification, with the switch drive circuit comprising a secondary coil of the first transformer.
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Citations
22 Claims
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1. A resonant converter comprising:
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a resonant converter primary stage including; a first switch; a second switch coupled in series with the first switch; a controller coupled to the first switch and the second switch and programmed to control operation of the first switch and the second switch; a first transformer comprising a primary coil coupled to a node between the first switch and the second switch; and a resonant inductor coupled to the primary coil of the first transformer; a resonant converter secondary stage including; a second transformer comprising; a primary coil coupled to the resonant inductor; and a secondary coil comprising a first coil section and a second coil section coupled to the first coil section; a third switch coupled to the first coil section of the secondary coil of the second transformer; and a fourth switch coupled to the second coil section of the secondary coil of the second transformer; and a switch drive circuit configured to drive the third switch and the fourth switch for synchronous rectification, wherein the switch drive circuit comprises a secondary coil of the first transformer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for synchronous rectification in a resonant converter, the method comprising:
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providing a resonant converter primary stage comprising; providing a primary pair of switches; coupling a controller to the primary pair of switches, the controller configured to control operation of the primary pair of switches; coupling a primary coil of a current transformer to the primary pair of switches; and coupling a primary coil of a voltage transformer to the current transformer; providing a resonant converter secondary stage comprising; providing a secondary coil of the voltage transformer; and coupling a pair of secondary switches to the secondary coil of the voltage transformer; coupling a switch drive circuit to the pair of secondary switches, the switch drive circuit comprising a secondary coil of the current transformer; providing power to the resonant converter primary stage; and controlling the primary pair of switches with the controller to direct power through the primary coil of the current transformer and the primary coil of the voltage transformer; wherein the power flowing through the primary coil of the voltage transformer causes power to flow through the secondary coil of the voltage transformer; wherein the power flowing through the primary coil of the current transformer causes power to flow through the secondary coil of the current transformer; and wherein the power flowing through the secondary coil of the current transformer causes the switch drive circuit to drive the pair of secondary switches to direct the power flowing through the secondary coil of the voltage transformer to a load. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A clamped series resonant converter comprising:
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a half bridge circuit comprising a first switch and a second switch coupled in series with the first switch; a first controller coupled to the half bridge circuit and programmed to control the half bridge circuit; a pair of diodes coupled in parallel with the half bridge circuit, the pair of diodes comprising a first diode in series with a second diode; a first capacitor coupled in parallel with the second diode of the pair of diodes; an inductor coupled to a node between the first switch of the half bridge circuit and the second switch of the half bridge circuit; a transformer comprising; a primary coil coupled to the inductor and to a node between the first diode and the second diode; and a secondary coil comprising a first coil section and a second coil section coupled to the first coil section; a pair of switches including a third switch coupled to the first coil section of the secondary coil of the transformer and a fourth switch coupled to the second coil section of the secondary coil of the transformer; a first current sensor coupled to the third switch for sensing the current through the third switch; a second current sensor coupled to the fourth switch for sensing the current through the fourth switch; and a second controller coupled to the first current sensor, the second current sensor, and the pair of switches and programmed to control the pair of switches synchronously with the half bridge circuit based on the current sensed by the first current sensor and the second current sensor. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification