High-precision drain-source voltage detection circuit for synchronous rectification of LLC resonant converter

By constructing a high-precision drain-source voltage detection circuit, the problems of low detection accuracy and low applicable voltage level of synchronous rectifier tube drain-source voltage are solved, realizing efficient synchronous rectification control, which is suitable for LLC resonant converters of various voltage levels.

CN117595673BActive Publication Date: 2026-07-24XI AN JIAOTONG UNIV
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Patent Information

Application Number
CN202311576674.1
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2023-11-23
Publication Date
2026-07-24
Estimated Expiration
2043-11-23

AI Technical Summary

Technical Problem

Existing synchronous rectifier drain-source voltage detection schemes suffer from low detection accuracy and low applicable voltage levels, which affect the efficiency and power density of LLC resonant converters.

Method used

A high-precision drain-source voltage detection circuit is constructed by employing a drain-source turn-off voltage blocking circuit, a drain-source turn-on voltage compensation circuit, a drain-source turn-off voltage clamping circuit, and a constant current source circuit, combined with operational amplifiers and different types of diodes. The detection accuracy and applicable voltage levels are improved through differential compensation and clamping technology.

Benefits of technology

It achieves high-precision drain-source voltage detection, is applicable to LLC resonant converters of various voltage levels, improves the efficiency and applicability of synchronous rectification control, and avoids noise interference caused by resistor voltage division.

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Abstract

The application discloses a high-precision drain-source voltage detection circuit for synchronous rectification of an LLC resonant converter, one end of a drain-source off voltage blocking circuit is connected with a drain electrode of a synchronous rectification tube to be detected, the other end of the drain-source off voltage blocking circuit is connected with a cathode of a compensation diode, an anode of a clamping diode and a same-direction input end of an operational amplifier, one end of a first current-limiting resistor is connected with an anode of the compensation diode, the other end of the first current-limiting resistor is connected with a cathode of the clamping diode and a constant-current source circuit, one end of a first compensation resistor is connected with the anode of the compensation diode, the other end of the first compensation resistor is connected with a reverse input end of the operational amplifier, a cathode of a stabilizing tube is connected with the cathode of the clamping diode, an anode of the stabilizing tube is grounded, and an output end of the operational amplifier is used as a final output signal end; and the circuit can accurately detect the drain-source voltage of the LLC resonant converter.
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