CN217010708U

CN217010708U - LLC resonant circuit

Info

Publication number: CN217010708U
Application number: CN202220520825.6U
Authority: CN
Inventors: 徐昌荣; 吴子佳
Original assignee: Wuxi Xuanji Electronic Technology Co ltd
Current assignee: Wuxi Xuanji Electronic Technology Co ltd
Priority date: 2022-03-10
Filing date: 2022-03-10
Publication date: 2022-07-19
Anticipated expiration: 2032-03-10

Abstract

The utility model relates to an LLC resonant circuit, comprising a square wave generator for generating a square wave signal, a resonant network for converting the square wave signal into an oscillation signal and a synchronous rectification module; the square wave generating circuit generates square wave signals, the square wave signals are fed into the resonant network and generate oscillation signals through resonance, the oscillation signals are transmitted to the synchronous rectification module through the transformer, the synchronous rectifier in the synchronous rectification module is controlled by the first MOS tube and the second MOS tube to be closed in turn, corresponding half-wave waves are transmitted to the input end of the synchronous rectification module in a wave division mode, and then rectification output is conducted, so that the oscillation signals are rectified synchronously, power consumption is reduced, and rectification efficiency is improved.

Description

LLC resonant circuit

Technical Field

The utility model relates to the technical field of charging circuits, in particular to an LLC resonant circuit.

Background

Compared with a series resonant converter and a parallel resonant converter, the LLC resonant converter has a small frequency change when the load and input change is large, and can implement zero-voltage conversion by switching in a full range, so that the LLC resonant converter is of great interest in the field of power supply design. Generally, the LLC resonant topology includes a square wave generator, a resonant network, and a rectifier network, and most of the rectifier networks directly employ diodes for rectification, which is likely to cause large power consumption and low efficiency.

SUMMERY OF THE UTILITY MODEL

In view of this, an object of the present invention is to provide an LLC resonant circuit, which can solve the problem of large power consumption of a rectifier network in the LLC resonant circuit in the prior art.

In order to achieve the purpose, the utility model adopts the following technical scheme:

the LLC resonant circuit comprises a square wave generator for generating a square wave signal, a resonant network for converting the square wave signal into an oscillation signal and a synchronous rectification module;

the square wave generator is connected with the input end of the resonant network, and the resonant network is connected with the rectifying circuit through a transformer;

the synchronous rectification module comprises a synchronous rectifier, a first rectification switch tube and a second rectification switch tube, a primary winding of the transformer is connected with the resonant network, two ends of a secondary winding of the transformer are respectively connected with one end of the first rectification switch tube and one end of the second rectification switch tube, two ends of the secondary winding are simultaneously connected with an input end of the synchronous rectifier, a control end of the first rectification switch tube and a control end of the second rectification switch tube are connected with a control end of the synchronous rectifier, and the other end of the first rectification switch tube and the other end of the second rectification switch tube are connected with an output end of the synchronous rectifier and serve as a power output end.

Optionally, the square wave generator includes a resonant controller, a first switching tube and a second switching tube, the first switching tube and the second switching tube form a half bridge, a control end of the first switching tube and a control end of the second switching tube are both connected to the resonant controller, and the resonant controller is configured to control the first switching tube and the second switching tube to alternately operate.

Optionally, the resonant network is connected to the synchronous rectification module through a transformer, the transformer includes a primary winding and a secondary winding, the primary winding is coupled to the secondary winding, and the resonant network includes a first resonant inductor, a second resonant inductor, and a resonant capacitor;

one end of the first resonant inductor is connected with an external power supply, and the other end of the first resonant inductor is connected with one end of the half bridge;

one end of the second resonant inductor is connected with the central point of the half bridge, and the other end of the second resonant inductor is connected with one end of the primary winding;

one end of the resonant capacitor is connected with the other end of the half bridge, and the other end of the resonant capacitor is connected with the other end of the primary winding.

Optionally, the power output end is provided with a filter capacitor.

Optionally, the first switch tube and the second switch tube are both connected in parallel to provide a diode and an RC snubber circuit.

The utility model has the beneficial effects that: according to the LLC resonant circuit, the square wave signal is generated through the square wave generating circuit, the square wave signal is fed into the resonant network and generates an oscillation signal through resonance, the oscillation signal is transmitted to the synchronous rectification module through the transformer, the synchronous rectifier in the synchronous rectification module controls the first MOS tube and the second MOS tube to be closed in turn, the corresponding half-wave is transmitted to the input end of the synchronous rectification module in a wave division mode, and then rectification output is performed, so that the oscillation signal is rectified synchronously, the power consumption is reduced, and the rectification efficiency is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that for those skilled in the art, other relevant drawings can be obtained on the basis of these drawings without inventive effort:

FIG. 1 is a circuit diagram of a square wave generator and a resonant network of the present invention;

fig. 2 is a circuit diagram of the synchronous rectification module of the present invention.

Detailed Description

As shown in fig. 1-2: an LLC resonant circuit in this embodiment includes a square wave generator for generating a square wave signal, a resonant network for converting the square wave signal into an oscillating signal, and a synchronous rectification module.

The square wave generator is connected with the input end of the resonance network, and the resonance network is connected with the rectifying circuit through the transformer.

The synchronous rectification module comprises a synchronous rectifier U203, a first rectification switch tube MS201 and a second rectification switch tube MS201, a primary winding of a transformer is connected with a resonant network, two ends of a secondary winding of the transformer are respectively connected with one end of the first rectification switch tube MS201 and one end of the second rectification switch tube MS201, two ends of the secondary winding are simultaneously connected with an input end of the synchronous rectifier U203, a control end of the first rectification switch tube MS201 and a control end of the second rectification switch tube MS201 are connected with a control end of the synchronous rectifier U203, and the other end of the first rectification switch tube MS201 and the other end of the second rectification switch tube MS201 are both connected with an output end of the synchronous rectifier U203 and serve as a power output end.

Specifically, the first rectifying switch tube MS201 and the second rectifying switch tube MS202 are MOS tubes, a drain of the first rectifying switch tube MS201 and a drain of the second rectifying switch tube MS202 are connected to two ends of the secondary winding, a source of the first rectifying switch tube MS201 and a source of the second rectifying switch tube MS202 are connected to an output line, and a gate of the first rectifying switch tube MS201 and a gate of the second rectifying switch tube MS202 are respectively connected to two control ends G1 and G2 of the synchronous rectifier U203; meanwhile, two ends of the secondary winding are respectively connected with two input ends VD1 and VD2 of the synchronous rectifier U203 after being connected with the resistors in series; meanwhile, the control end of the synchronous rectifier U203 is also used as an output end to be connected with an output line; VD1 and VD2 represent internal rectifier diodes, and the synchronous rectifier controls the corresponding switch tube to be disconnected according to whether the oscillation signal is in the upper half part or the lower half part, so that the rectifier diodes in the synchronous collator U203 can rectify the corresponding signal half-area, and the synchronous collator is more efficient and energy-saving.

In this embodiment, specifically, the resonant controller U1, the first switch tube MS2, and the second switch tube MS3, the first switch tube MS2 and the second switch tube MS3 form a half bridge, a control end of the first switch tube MS2 and a control end of the second switch tube MS3 are both connected to the resonant controller, the first switch tube MS2 and the second switch tube MS3 are both MOS tubes, a control end of each of the MOS tubes is a gate, the resonant controller is configured to control the first switch and the second switch tube to alternately operate, in some embodiments, the model of the resonant controller is HR1000A, the gate of the first switch tube MS2 is connected to a high-side gate driving end HG of the resonant controller, and the gate of the second switch tube MS3 is connected to a low-side gate driving end LG of the resonant controller; in this embodiment, the duty ratios of the first switch tube MS2 and the second switch tube MS3 are both 0.5, and the control is performed by a complementary frequency modulation control method with a fixed dead zone.

In this embodiment, specifically, the resonant network is connected to the synchronous rectification module through a transformer, the transformer includes a primary winding and a secondary winding, the primary winding is coupled to the secondary winding, and the resonant network includes a first resonant inductor L1, a second resonant inductor L2, and a resonant capacitor Cr; one end of the first resonant inductor is connected with an external power supply, and the other end of the first resonant inductor is connected with one end of the half bridge; one end of the second resonant inductor is connected with the central point of the half bridge, and the other end of the second resonant inductor is connected with one end of the primary winding; one end of the resonance capacitor is connected with the other end of the half bridge, and the other end of the resonance capacitor is connected with the other end of the primary winding;

optionally, a filter capacitor EC201 is disposed at the power output end, and the filter capacitor filters the rectified signal.

Optionally, the first switch tube MS201 and the second switch tube MS202 are both provided with a diode and an RC snubber circuit in parallel, and the RC snubber circuit includes a resistor and a capacitor connected in series.

In summary, in the LLC resonant circuit of the present invention, the square wave generating circuit generates the square wave signal, the square wave signal is fed into the resonant network to generate the oscillation signal through resonance, and then the oscillation signal is transmitted to the synchronous rectification module through the transformer, the synchronous rectifier U203 in the synchronous rectification module switches off in turn by controlling the first MOS transistor and the second MOS transistor, and transmits the corresponding half-wave to the input end of the synchronous rectification module by wavelength division, and then rectifies and outputs the half-wave, thereby synchronously rectifying the oscillation signal, reducing power consumption, and improving rectification efficiency.

Finally, the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the novel technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims

1. An LLC resonant circuit, characterized in that: the device comprises a square wave generator for generating a square wave signal, a resonance network for converting the square wave signal into an oscillation signal and a synchronous rectification module;

the square wave generator is connected with the input end of the resonant network, and the resonant network is connected with the rectifying module through a transformer;

the synchronous rectification module comprises a synchronous rectifier, a first rectification switch tube and a second rectification switch tube, a primary winding of the transformer is connected with the resonant network, two ends of a secondary winding of the transformer are respectively connected with one end of the first rectification switch tube and one end of the second rectification switch tube, two ends of the secondary winding are simultaneously connected with an input end of the synchronous rectifier, a control end of the first rectification switch tube and a control end of the second rectification switch tube are both connected with a control end of the synchronous rectifier, and the other end of the first rectification switch tube and the other end of the second rectification switch tube are both connected with an output end of the synchronous rectifier and serve as a power output end.

2. An LLC resonant circuit as claimed in claim 1, wherein: the square wave generator comprises a resonance controller, a first switch tube and a second switch tube, wherein the first switch tube and the second switch tube form a half bridge, the control ends of the first switch tube and the second switch tube are connected with the resonance controller, and the resonance controller is used for controlling the first switch and the second switch tube to work alternately.

3. An LLC resonant circuit as claimed in claim 2, wherein: the resonance network is connected with the synchronous rectification module through a transformer, the transformer comprises a primary winding and a secondary winding, the primary winding is coupled with the secondary winding, and the resonance network comprises a first resonance inductor, a second resonance inductor and a resonance capacitor;

4. An LLC resonant circuit as claimed in claim 1, wherein: and the power output end is provided with a filter capacitor.

5. An LLC resonant circuit as claimed in claim 2, wherein: the first switch tube and the second switch tube are both provided with a diode and an RC buffer circuit in parallel.