A parallel CLL resonant converter

Abstract

The utility model relates to a parallel CLL resonant converter relates to the technical field of isolated DC / DC converter, it includes. The utility model adopts magnetic integration technology, and the second resonant inductance in first resonant cavity circuit and fourth resonant inductance in second resonant cavity circuit are integrated to the leakage inductance of high frequency transformer primary side first winding and primary side second winding respectively, and first resonant inductance and third resonant inductance share the magnetic core simultaneously, thereby realize the purpose of current equalization, and the topology structure that the utility model adopts is simple, increases power density, realizes the purpose of current automatic equalization.

Description

Technical Field

[0001] This utility model relates to the field of isolated DC / DC converter technology, and in particular to a parallel CLL resonant converter. Background Technology

[0002] Isolated DC / DC converters are widely used in bidirectional power supplies, AC / DC microgrids, and charging piles. When a resonant cavity structure is added, they have high efficiency due to the ability to achieve soft switching, and are thus widely used in constant voltage, wide voltage, and ultra-wide voltage scenarios.

[0003] When the resonant cavity structure has only one resonant element, soft switching is difficult to achieve. With two resonant elements, the transformer's magnetizing inductance is not fully utilized. However, with three resonant elements, the resonant characteristics are fully utilized, giving isolated DC / DC converters good soft-switching performance, efficiency, and cost-effectiveness. Among these, the LLC resonant converter has gained widespread application. However, because the magnetizing inductance of the LLC resonant converter is clamped by the load, its efficiency decreases under light load. To solve this problem, the CLL resonant converter was proposed. Its resonant cavity contains two resonant inductors, connected in parallel and series with the primary side of the transformer, respectively. This avoids the magnetizing inductance clamping problem of the LLC resonant converter, thereby improving efficiency under light load. In high-power applications, multiple CLL resonant converters need to be operated in parallel to improve efficiency and reduce cost. In 2023, Huang Hewei, in his paper "Optimization Method for Return Power of Half-Bridge CLL Resonant Converter Based on Equivalent Resonant Cavity," optimized parameters based on the half-bridge CLL topology to reduce return power, making it suitable for small and medium power applications. Connecting multiple CLL resonant converters directly in parallel can increase the output capability. However, there is still a load current sharing problem between parallel circuits, and multiple resonant inductors will increase the size. Utility Model Content

[0004] The purpose of this invention is to address the problems in the prior art by providing a parallel CLL resonant converter.

[0005] To solve the above-mentioned technical problems, this utility model adopts the following technical solution: a parallel CLL resonant converter, comprising a primary-side first parallel branch, a primary-side second parallel branch, a high-frequency transformer, and a secondary-side full-bridge rectifier circuit, characterized in that:

[0006] The primary-side first parallel branch includes a primary-side first parallel full-bridge circuit and a first resonant cavity circuit connected in sequence; the primary-side first parallel full-bridge circuit includes a first branch formed by primary-side first switch S1 and primary-side second switch S2 connected in series, and a second branch formed by primary-side third switch S3 and primary-side fourth switch S4 connected in series, with the second branch connected in parallel to both ends of the first branch; the node where the primary-side first switch S1 and primary-side second switch S2 are connected in series is connected to one end of the input terminal of the first resonant cavity circuit, and the node where the primary-side third switch S3 and primary-side fourth switch S4 are connected in series is connected to the other end of the input terminal of the first resonant cavity circuit; one end of the output terminal of the first resonant cavity circuit is connected to one end of the primary-side first winding of the high-frequency transformer, and the other end of the output terminal of the first resonant cavity circuit is connected to the other end of the primary-side first winding of the high-frequency transformer.

[0007] The primary-side second parallel branch includes a primary-side second parallel full-bridge circuit and a second resonant cavity circuit connected in sequence; the primary-side second parallel full-bridge circuit includes a third branch formed by the primary-side fifth switch S5 and the primary-side sixth switch S6 connected in series, and a fourth branch formed by the primary-side seventh switch S7 and the primary-side eighth switch S8 connected in series, with the third branch connected in parallel to both ends of the fourth branch; the node where the primary-side fifth switch S5 and the primary-side sixth switch S6 are connected in series is connected to one end of the input terminal of the second resonant cavity circuit, and the node where the primary-side seventh switch S7 and the primary-side eighth switch S8 are connected in series is connected to the other end of the input terminal of the second resonant cavity circuit; one end of the output terminal of the first resonant cavity circuit is connected to one end of the primary-side second winding of the high-frequency transformer, and the other end of the output terminal of the first resonant cavity circuit is connected to the other end of the primary-side second winding of the high-frequency transformer.

[0008] The turns ratio of the primary winding to the secondary winding of the high-frequency transformer is n:1, and the turns ratio of the primary winding to the secondary winding of the high-frequency transformer is n:1; the first resonant cavity circuit is sequentially connected to the primary winding of the high-frequency transformer, and the second resonant cavity circuit is sequentially connected to the primary winding of the high-frequency transformer; the secondary winding of the high-frequency transformer is sequentially connected to the secondary full-bridge rectifier circuit.

[0009] The secondary-side full-bridge rectifier circuit includes the ninth secondary-side switch S9 and the tenth secondary-side switch S1. 10 The fifth branch formed by series connection, and the eleventh secondary switch S 11 With the twelfth switch S on the secondary side 12 The sixth branch is formed by series connection, and the fifth branch is connected in parallel to both ends of the sixth branch; the ninth switch S9 on the secondary side and the tenth switch S9 on the secondary side are connected in series. 10 The series-connected node is connected to one end of the secondary winding of the high-frequency transformer, and the eleventh secondary switch S 11 With the twelfth switch S on the secondary side12 The node connected in series is connected to the other end of the secondary winding of the high-frequency transformer.

[0010] Preferably, the first resonant cavity circuit includes a first resonant capacitor C connected in series. r1 Second resonant inductor L r2 and the first winding of the primary side of the high-frequency transformer; the first resonant inductor L r1 One end is connected to the first resonant capacitor C r1 With the second resonant inductor L r2 The first resonant inductor L is connected in series. r1 The other end is connected to the node where the third primary switch S3 and the fourth primary switch S4 are connected in series; the second resonant cavity circuit includes a second resonant capacitor C connected in series. r2 Fourth resonant inductor L r4 And the second winding of the primary side of the high-frequency transformer; the third resonant inductor L r3 One end is connected to the second resonant capacitor C r2 With the fourth resonant inductor L r4 The third resonant inductor L is connected in series. r3 The other end is connected to the node where the seventh switch S7 and the eighth switch S8 on the primary side are connected in series.

[0011] More preferably, the input ports of the first parallel branch of the primary side and the second parallel branch of the primary side are connected in parallel.

[0012] More preferably, the first resonant inductor L r1 With the third resonant inductor L r3 They share a single magnetic core and are coupled in opposite directions.

[0013] More preferably, the first resonant inductor L r1 With the third resonant inductor L r3 The shared magnetic core is either an EI type core or an EE type core.

[0014] More preferably, the first resonant inductor L r1 With the third resonant inductor L r3 The windings are located on the two side posts of the magnetic core, and the middle post of the magnetic core has an air gap.

[0015] More preferably, the second resonant inductor L r2 The leakage inductance of the first winding of the primary side of the high-frequency transformer; the third resonant inductor L r3 This refers to the leakage inductance of the second winding on the primary side of a high-frequency transformer.

[0016] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0017] This invention is completely different from existing CLL resonant converters. The first resonant inductor L in the first resonant cavity circuit and the second resonant cavity circuit... r1 With the third resonant inductor L r3 Sharing a single magnetic core reduces cost and increases power density; due to the first resonant inductor L in the first and second resonant cavity circuits... r1 With the third resonant inductor L r3 They share a single magnetic core, thus utilizing the mutual inductance generated by the coupled magnetic flux between them to achieve load current sharing control, preventing excessive current from flowing through one of the resonant cavity circuits, resulting in a simple structure; the second resonant inductor L r2 The leakage inductance of the first winding of the primary side of the high-frequency transformer, and the third resonant inductance L r3 The leakage inductance of the second winding on the primary side of the high-frequency transformer is used to realize the second resonant inductance L. r2 and the third resonant inductor L r3 Magnetic integration with high-frequency transformers improves power density. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the parallel CLL resonant converter structure of this utility model;

[0019] Figure 2 This is a schematic diagram of the shared magnetic core of the resonant inductor in the parallel CLL resonant converter of this utility model.

[0020] In the picture:

[0021] 11. Primary-side first parallel full-bridge circuit; 12. First resonant cavity circuit; 21. Primary-side second parallel full-bridge circuit; 22. Second resonant cavity circuit; 3. High-frequency transformer; 4. Secondary-side full-bridge rectifier circuit. Detailed Implementation

[0022] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention.

[0023] like Figure 1 As shown, a parallel CLL resonant converter includes a primary side first parallel branch, a primary side second parallel branch, a high-frequency transformer 3, and a secondary side full-bridge rectifier circuit 4.

[0024] In the above structure, the primary-side first parallel branch includes a primary-side first parallel full-bridge circuit 11 and a first resonant cavity circuit 12 connected in sequence; the primary-side first parallel full-bridge circuit includes a first branch formed by the primary-side first switch S1 and the primary-side second switch S2 connected in series, and a second branch formed by the primary-side third switch S3 and the primary-side fourth switch S4 connected in series, with the second branch connected in parallel to both ends of the first branch; the node where the primary-side first switch S1 and the primary-side second switch S2 are connected in series is connected to one end of the input terminal of the first resonant cavity circuit, and the node where the primary-side third switch S3 and the primary-side fourth switch S4 are connected in series is connected to the other end of the input terminal of the first resonant cavity circuit; one end of the output terminal of the first resonant cavity circuit is connected to one end of the primary-side first winding of the high-frequency transformer, and the other end of the output terminal of the first resonant cavity circuit is connected to the other end of the primary-side first winding of the high-frequency transformer.

[0025] The primary-side second parallel branch includes a primary-side second parallel full-bridge circuit 21 and a second resonant cavity circuit 22 connected in sequence; the primary-side second parallel full-bridge circuit includes a third branch formed by the primary-side fifth switch S5 and the primary-side sixth switch S6 connected in series, and a fourth branch formed by the primary-side seventh switch S7 and the primary-side eighth switch S8 connected in series, with the third branch connected in parallel to both ends of the fourth branch; the node where the primary-side fifth switch S5 and the primary-side sixth switch S6 are connected in series is connected to one end of the input terminal of the second resonant cavity circuit, and the node where the primary-side seventh switch S7 and the primary-side eighth switch S8 are connected in series is connected to the other end of the input terminal of the second resonant cavity circuit; one end of the output terminal of the first resonant cavity circuit is connected to one end of the primary-side second winding of the high-frequency transformer, and the other end of the output terminal of the first resonant cavity circuit is connected to the other end of the primary-side second winding of the high-frequency transformer.

[0026] Furthermore, the turns ratio of the primary winding to the secondary winding of the high-frequency transformer is n:1, and the turns ratio of the primary winding to the secondary winding of the high-frequency transformer is n:1; the first resonant cavity circuit is sequentially connected to the primary winding of the high-frequency transformer, and the second resonant cavity circuit is sequentially connected to the primary winding of the high-frequency transformer; the secondary winding of the high-frequency transformer is sequentially connected to the secondary full-bridge rectifier circuit.

[0027] The secondary-side full-bridge rectifier circuit includes the ninth secondary-side switch S9 and the tenth secondary-side switch S1. 10 The fifth branch formed by series connection, and the eleventh secondary switch S 11 With the twelfth switch S on the secondary side 12 The sixth branch is formed by series connection, and the fifth branch is connected in parallel to both ends of the sixth branch; the ninth switch S9 on the secondary side and the tenth switch S on the secondary side... 10 The series connection node is connected to one end of the secondary winding of the high-frequency transformer, and the eleventh secondary switch S... 11 With the twelfth switch S on the secondary side 12The node connected in series is connected to the other end of the secondary winding of the high-frequency transformer.

[0028] Preferably, the first resonant cavity circuit includes a first resonant capacitor C connected in series. r1 Second resonant inductor L r2 and the first winding of the primary side of the high-frequency transformer; the first resonant inductor L r1 One end is connected to the first resonant capacitor C r1 With the second resonant inductor L r2 The first resonant inductor L is connected in series. r1 The other end is connected to the node where the third primary switch S3 and the fourth primary switch S4 are connected in series; the second resonant cavity circuit includes a second resonant capacitor C connected in series. r2 Fourth resonant inductor L r4 And the second winding of the primary side of the high-frequency transformer; the third resonant inductor L r3 One end is connected to the second resonant capacitor C r2 With the fourth resonant inductor L r4 The third resonant inductor L is connected in series. r3 The other end is connected to the node where the seventh switch S7 and the eighth switch S8 on the primary side are connected in series.

[0029] In this embodiment, the input ports of the first parallel branch of the primary side and the second parallel branch of the primary side are connected in parallel.

[0030] Preferably, the first resonant inductor L r1 With the third resonant inductor L r3 They share a single magnetic core and are reverse-coupled. The first resonant inductor L... r1 With the third resonant inductor L r3 The shared magnetic core is an EI type or an EE type magnetic core. Furthermore, the first resonant inductor L... r1 With the third resonant inductor L r3 The windings are located on the two side posts of the magnetic core, and the middle post of the magnetic core has an air gap.

[0031] Based on the above, the second resonant inductor L r2 The leakage inductance of the first winding of the primary side of the high-frequency transformer; the third resonant inductance L r3 This refers to the leakage inductance of the second winding on the primary side of a high-frequency transformer.

[0032] Specifically, such as Figure 2 As shown, the first resonant inductor L r1 The winding is located at the core side post I, and the third resonant inductor L r3 The winding is located on the side post III of the magnetic core, and the middle post II of the magnetic core has an air gap. The first resonant inductor L r1 The winding and the third resonant inductor L r3The windings are reverse-coupled, and the first resonant inductor L r1 The magnetic flux is Φ r1 The third resonant inductor L r3 The magnetic flux is Φ r3 The first resonant inductor L r1 The voltage of the winding is:

[0033] ;

[0034] Third resonant inductor L r3 The voltage of the winding is:

[0035] .

[0036] Where M is the first resonant inductance L r1 With the third resonant inductor L r3 The mutual inductance between them. When the first resonant inductor L r1 When the current i1 increases, the third resonant inductor L r3 The voltage u of the winding Lr3 The third resonant inductor L decreases. r3 The current i3 in the winding increases; when the third resonant inductor L r3 When the current i3 increases, the first resonant inductor L r1 The voltage u of the winding Lr1 The first resonant inductor L decreases. r1 As the current i1 in the winding increases, the first resonant inductor L eventually... r1 The current i1 and the third resonant inductor L r3 The currents i3 are equal, thus achieving current balance.

[0037] The parallel CLL resonant converter provided in the above embodiment is completely different from the existing CLL resonant converter. It adopts magnetic integration technology to improve power density, utilizes the effect of coupled inductors to achieve load current sharing control, and has a simpler structure.

[0038] To facilitate understanding by those skilled in the art of the improvements of this utility model compared to the prior art, some of the accompanying drawings and descriptions of this utility model have been simplified. The above embodiments are preferred implementations of this utility model. In addition, this utility model can be implemented in other ways. Any obvious substitutions without departing from the concept of this technical solution are within the protection scope of this utility model.

Claims

1. A parallel CLL resonant converter, comprising a primary-side first parallel branch, a primary-side second parallel branch, a high-frequency transformer, and a secondary-side full-bridge rectifier circuit, characterized in that: The primary-side first parallel branch includes a primary-side first parallel full-bridge circuit and a first resonant cavity circuit connected in sequence; the primary-side first parallel full-bridge circuit includes a first branch formed by primary-side first switch S1 and primary-side second switch S2 connected in series, and a second branch formed by primary-side third switch S3 and primary-side fourth switch S4 connected in series, with the second branch connected in parallel to both ends of the first branch; the node where the primary-side first switch S1 and primary-side second switch S2 are connected in series is connected to one end of the input terminal of the first resonant cavity circuit, and the node where the primary-side third switch S3 and primary-side fourth switch S4 are connected in series is connected to the other end of the input terminal of the first resonant cavity circuit; one end of the output terminal of the first resonant cavity circuit is connected to one end of the primary-side first winding of the high-frequency transformer, and the other end of the output terminal of the first resonant cavity circuit is connected to the other end of the primary-side first winding of the high-frequency transformer. The primary-side second parallel branch includes a primary-side second parallel full-bridge circuit and a second resonant cavity circuit connected in sequence; the primary-side second parallel full-bridge circuit includes a third branch formed by the primary-side fifth switch S5 and the primary-side sixth switch S6 connected in series, and a fourth branch formed by the primary-side seventh switch S7 and the primary-side eighth switch S8 connected in series, with the third branch connected in parallel to both ends of the fourth branch; the node where the primary-side fifth switch S5 and the primary-side sixth switch S6 are connected in series is connected to one end of the input terminal of the second resonant cavity circuit, and the node where the primary-side seventh switch S7 and the primary-side eighth switch S8 are connected in series is connected to the other end of the input terminal of the second resonant cavity circuit; one end of the output terminal of the first resonant cavity circuit is connected to one end of the primary-side second winding of the high-frequency transformer, and the other end of the output terminal of the first resonant cavity circuit is connected to the other end of the primary-side second winding of the high-frequency transformer. The turns ratio of the primary winding to the secondary winding of the high-frequency transformer is n:1, and the turns ratio of the primary winding to the secondary winding of the high-frequency transformer is n:1; the first resonant cavity circuit is sequentially connected to the primary winding of the high-frequency transformer, and the second resonant cavity circuit is sequentially connected to the primary winding of the high-frequency transformer; the secondary winding of the high-frequency transformer is sequentially connected to the secondary full-bridge rectifier circuit. The secondary side full-bridge rectifier circuit comprises a secondary side ninth switch S9 and a secondary side tenth switch S 10 The fifth branch is formed in series, and a secondary side eleventh switch S 11 The sixth branch is formed in series, and a secondary side twelfth switch S 12 The fifth branch is formed in series, and a secondary side ninth switch S9 and a secondary side tenth switch S 10 The node connected in series is connected with one end of the high-frequency transformer secondary side winding, and a secondary side eleventh switch S 11 The node connected in series is connected with one end of the high-frequency transformer secondary side winding, and a secondary side twelfth switch S 12 The node connected in series is connected with one end of the high-frequency transformer secondary side winding, and a secondary side twelfth switch S 2. The parallel CLL resonant converter according to claim 1, characterized in that: The first resonant cavity circuit includes a first resonant capacitor C connected in series. r1 Second resonant inductor L r2 and the first winding of the primary side of the high-frequency transformer; the first resonant inductor L r1 One end is connected to the first resonant capacitor C r1 With the second resonant inductor L r2 The first resonant inductor L is connected in series. r1 The other end is connected to the node where the third primary switch S3 and the fourth primary switch S4 are connected in series; the second resonant cavity circuit includes a second resonant capacitor C connected in series. r2 Fourth resonant inductor L r4 And the second winding of the primary side of the high-frequency transformer; the third resonant inductor L r3 One end is connected to the second resonant capacitor C r2 With the fourth resonant inductor L r4 The third resonant inductor L is connected in series. r3 The other end is connected to the node where the seventh switch S7 and the eighth switch S8 on the primary side are connected in series.

3. The parallel CLL resonant converter according to claim 1, characterized in that: The input ports of the first parallel branch of the primary side and the second parallel branch of the primary side are connected in parallel.

4. The parallel CLL resonant converter according to claim 2, characterized in that: The first resonant inductor L r1 With the third resonant inductor L r3 They share a single magnetic core and are coupled in opposite directions.

5. The parallel CLL resonant converter according to claim 4, characterized in that: The first resonant inductor L r1 With the third resonant inductor L r3 The shared magnetic core is either an EI type core or an EE type core.

6. The parallel CLL resonant converter according to claim 5, characterized in that: The first resonant inductor L r1 With the third resonant inductor L r3 The windings are located on the two side posts of the magnetic core, and the middle post of the magnetic core has an air gap.

7. The parallel CLL resonant converter according to claim 2, characterized in that: The second resonant inductor L r2 The leakage inductance of the first winding on the primary side of the high-frequency transformer; The third resonant inductor L r3 This refers to the leakage inductance of the second winding on the primary side of a high-frequency transformer.

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