DC-DC conversion circuit, DC-DC converter and charging module

Abstract

The utility model discloses a DC-DC conversion circuit, a DC-DC converter and a charging module, the DC-DC conversion circuit with winding switching is obtained by adding a plurality of switch units in a plurality of secondary windings or a plurality of primary windings, and a part of the secondary windings or a part of the primary windings are connected in series with a compensation inductor. Compensation of resonant inductance parameters is realized, so that resonant inductance and resonant frequency of the DC-DC conversion circuit during winding switching are unchanged, and conversion efficiency of the DC-DC conversion circuit with winding switching and the DC-DC converter is effectively improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to power management technical field especially relates to a DC-DC conversion circuit, DC-DC converter and charging module. BACKGROUND

[0002] LLC circuit (resonant conversion circuit) is the high -efficient DC-DC conversion circuit widely used in power management and conversion, in order to realize higher conversion efficiency, make LLC circuit work in the circuit of fixed operating frequency work is called DCX circuit. In order to reduce the size of device, improve the conversion efficiency of DCX circuit, the inductance of resonant inductance of DCX circuit is usually designed to be relatively small, or directly use the leakage inductance of transformer as resonant inductance, to reduce the size of device, improve conversion efficiency.

[0003] In DCX circuit, winding switching function is added to improve gain, due to the limitation of transformer winding structure, the leakage inductance of transformer under different winding switching states is difficult to be same, and the change of the leakage inductance has a great influence on the resonant frequency, and further influences the conversion efficiency of DC-DC converter, which hinders the realization of high-efficiency conversion of DC-DC converter. UTILITY MODEL CONTENTS

[0004] The utility model solves the technical problem that the utility model provides a DC-DC conversion circuit, DC-DC converter and charging module, and aims at solving the problem of low conversion efficiency of DC-DC converter caused by leakage inductance change in the related art.

[0005] To solve the above technical problems, the utility model is realized in this way, a DC-DC conversion circuit, including transformer, primary side resonant conversion circuit and secondary side resonant conversion circuit;

[0006] The transformer includes at least one primary winding and a plurality of secondary windings in series, and the primary winding is magnetically coupled with each secondary winding.

[0007] The primary side resonant conversion circuit includes a first rectifier inverter unit and a first resonant circuit, the first rectifier inverter unit is used to convert the received primary side DC signal into a primary side AC signal to the first end of the first resonant circuit, the second end of the first resonant circuit is electrically connected to the first end of the primary winding, and the second end of the primary winding is electrically connected to the first rectifier inverter unit.

[0008] The secondary side resonant conversion circuit comprises at least one compensation inductor, a second rectification inversion unit, and a plurality of switch units corresponding to the plurality of secondary side windings; each of the secondary side windings is connected in series with the corresponding switch unit to form a corresponding branch circuit, at least one of the branch circuits is connected in series with the compensation inductor, and each of the branch circuits is configured to output a secondary side alternating current signal to the second rectification inversion unit, and the second rectification inversion unit is configured to convert the secondary side alternating current signal into a secondary side direct current signal.

[0009] Further, the number of the compensation inductors is less than the number of the secondary side windings.

[0010] Further, the transformer comprises two of the secondary side windings connected in series, the secondary side resonant conversion circuit comprises one of the compensation inductors and two of the switch units corresponding to the two of the secondary side windings, the two of the secondary side windings are connected in series with the corresponding switch units to form two of the branch circuits, and the compensation inductor is connected in series with one of the branch circuits.

[0011] Further, the secondary side resonant conversion circuit further comprises a second resonant circuit, each of the branch circuits in which the compensation inductor is connected in series is defined as a first branch circuit, and each of the branch circuits other than the first branch circuit among the plurality of branch circuits is defined as a second branch circuit, and the second resonant circuit is connected in series between one of the second branch circuits and the second rectification inversion unit.

[0012] The utility model further provides a DC-DC conversion circuit, including transformer, primary side resonant conversion circuit and secondary side resonant conversion circuit,

[0013] The transformer comprises a plurality of primary side windings and a plurality of secondary side windings, each of the primary side windings is magnetically coupled with each of the secondary side windings;

[0014] The primary side resonant conversion circuit comprises a first rectification inversion unit, a first resonant circuit, at least one compensation inductor, and a plurality of switch units corresponding to the plurality of primary side windings; each of the primary side windings is connected in series with the corresponding switch unit to form a corresponding branch circuit, each of the compensation inductors is connected in series with one of the branch circuits, the first rectification inversion unit is configured to convert a received primary side direct current signal into a primary side alternating current signal to a first end of the first resonant circuit, a second end of the first resonant circuit is electrically connected to first ends of the plurality of branch circuits, and second ends of the plurality of branch circuits are electrically connected to the first rectification inversion unit.

[0015] The secondary side resonant conversion circuit comprises a second rectification inversion unit, and the plurality of secondary side windings are configured to output a secondary side alternating current signal to the second rectification inversion unit, and the second rectification inversion unit is configured to convert the secondary side alternating current signal into a secondary side direct current signal.

[0016] Further, the number of the compensation inductors is less than the number of the primary side windings.

[0017] The utility model also provides a DC-DC converter, including the DC-DC conversion circuit as described above.

[0018] The utility model also provides a charging module, including the DC-DC converter as described above.

[0019] Compared with prior art, the DC-DC conversion circuit, the DC-DC converter and the charging module have the beneficial effects that: the DC-DC conversion circuit with winding switching is obtained by increasing a plurality of switching units in a plurality of secondary winding or a plurality of primary winding, and a part of secondary winding or a part of primary winding is connected in series with a compensation inductance, so that the compensation of resonant inductance parameters is realized, the resonant inductance and resonant frequency of the DC-DC conversion circuit during winding switching remain unchanged, and the conversion efficiency of the DC-DC conversion circuit with winding switching and the DC-DC converter is effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the equivalent circuit diagram of the DC-DC conversion circuit in some embodiments of the utility model;

[0021] Figure 2 is the equivalent circuit diagram of the DC-DC conversion circuit in some embodiments of the utility model;

[0022] Figure 3 is the equivalent circuit diagram of the DC-DC conversion circuit in some embodiments of the utility model;

[0023] Figure 4 is the equivalent circuit diagram of the DC-DC conversion circuit in some embodiments of the utility model. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the utility model more clear and apparent, the utility model is further explained in detail below in combination with the drawings and embodiments.

[0025] In the description of the disclosure, it should be understood that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features limited by "first", "second" can be explicitly or implicitly included one or more features. In the description of the disclosure, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0026] The word "exemplary" here means "serving as an example, embodiment or illustration". Any embodiment described as "exemplary" here is not necessarily to be construed as superior or better than other embodiments.

[0027] In addition, in order to better illustrate the present disclosure, numerous specific details are set forth in the following detailed description. One skilled in the art will understand that the present disclosure can be practiced without certain specific details, and the specific embodiments described herein are merely examples of the present disclosure and are not intended to limit the present disclosure. In some examples, methods, means, elements and circuits well known to those skilled in the art are not described in detail in order to highlight the main idea of the present disclosure.

[0028] In order to meet the charging needs of various scenarios, the output voltage range and conversion efficiency of the charging module product are increasingly required, for example, in the field of charging new energy vehicles, the output voltage range of the first generation of charging module is divided into 200-500V and 200-750V, and the two output voltage ranges are respectively for private cars equipped with low-voltage batteries and buses, buses and the like equipped with low-voltage batteries, and the conversion efficiency of the charging module is about 95%-96%. With the improvement of demand and the progress of technology, the output voltage range of the second generation of charging module is expanded to 200V-1000V, which can meet most of the charging needs, and the charging efficiency is continuously improved to 96%-97%. However, due to the limitations of the circuit topology in the gain of the charging efficiency, the output end of the DC-DC conversion circuit in the charging module usually needs to be designed as a series-parallel switching, a transformer winding turn ratio switching or a combination of the above two switching modes, so as to realize higher conversion gain.

[0029] However, due to the structure limitation of the transformer winding, when the winding of the transformer is switched, the leakage inductance thereof cannot be the same, which greatly affects the resonant frequency of the DC-DC conversion circuit, greatly reduces the conversion efficiency of the DC-DC converter, and even destroys the software switching implementation condition of the transformer winding switching, hindering the efficient conversion of the DC-DC converter.

[0030] Therefore, the present application provides a DC-DC conversion circuit, a DC-DC converter and a charging module, which can solve the problem of low conversion efficiency of the DC-DC conversion circuit with winding switching.

[0031] The DC-DC conversion circuit provided in the embodiment keeps the resonant parameters unchanged under different winding switching modes based on compensation inductance, and the DC-DC conversion circuit can be applied to various circuits including but not limited to LLC circuit, CLLC bidirectional conversion circuit, winding switching and series-parallel mixed LLC circuit, three-phase resonant circuit and the like.

[0032] In a first aspect of the embodiment, as shown in Figure 1 The DC-DC conversion circuit includes a transformer, a primary side resonant conversion circuit and a secondary side resonant conversion circuit.

[0033] A transformer includes at least one primary winding and multiple secondary windings connected in series, with the primary windings magnetically coupled to each secondary winding.

[0034] The primary-side resonant converter circuit includes a first rectifier-inverter unit and a first resonant circuit. The first rectifier-inverter unit is used to convert the received primary-side DC signal into a primary-side AC signal to the first terminal of the first resonant circuit. The second terminal of the first resonant circuit is electrically connected to the first terminal of the primary-side winding, and the second terminal of the primary-side winding is electrically connected to the first rectifier-inverter unit.

[0035] The secondary resonant converter circuit includes at least one compensation inductor, a second rectifier-inverter unit, and a switching unit corresponding to multiple secondary windings. Each secondary winding is connected in series with the corresponding switching unit to form a corresponding branch. At least one branch is connected in series with a compensation inductor. Each branch is used to output the secondary AC signal to the second rectifier-inverter unit, which is used to convert the secondary AC signal into a secondary DC signal.

[0036] In this embodiment, a DC-DC converter circuit with winding switching is obtained by adding multiple switching units to multiple secondary windings or multiple primary windings. Furthermore, by connecting a portion of the secondary windings or a portion of the primary windings in series with a compensation inductor, the resonant inductance parameters are compensated, so that the resonant inductance and resonant frequency of the DC-DC converter circuit remain unchanged during winding switching, effectively improving the conversion efficiency of the DC-DC converter circuit with winding switching and the DC-DC converter.

[0037] Preferably, the first resonant circuit includes a first resonant inductor Lr and a first resonant capacitor Cr, and the first resonant inductor Lr, the first resonant capacitor Cr and the primary winding Np are connected in series.

[0038] Furthermore, the number of compensating inductors is less than the number of secondary windings.

[0039] Furthermore, the transformer includes two secondary windings connected in series. The secondary resonant converter circuit includes a compensating inductor and two switching units corresponding to the two secondary windings. Each of the two secondary windings is connected in series with the corresponding switching unit to form a corresponding branch. The compensating inductor is connected in series in one branch.

[0040] Specifically, such as Figure 1 As shown, in the first embodiment, the transformer includes a first secondary winding Ns1 and a second secondary winding Ns2. The secondary resonant converter circuit includes a compensation inductor Lcp, and a first switching unit K1 and a second switching unit K2 corresponding to the first secondary winding Ns1 and the second secondary winding Ns2, respectively. The compensation inductor Lcp is connected in series in the branch formed by the first secondary winding Ns1 and the first switching unit K1.

[0041] In the above embodiments, the working principle of the DC-DC converter circuit is as follows:

[0042] The DC-DC conversion circuit has two operation modes, namely a first operation mode and a second operation mode.

[0043] In the first operation mode, the first switch unit K1 is closed, the second switch unit K2 is opened, the first secondary winding Ns1 and the second secondary winding Ns2 are connected in series, the first secondary winding Ns1 and the second secondary winding Ns2 jointly serve as the secondary winding of the transformer, and the transformer turn ratio is In the first operation mode, the primary side leakage inductance of the corresponding transformer is Lk1.

[0044] In the second operation mode, the first switch unit K1 is opened, the second switch unit K2 is closed, the first secondary winding Ns1 is not connected to the circuit, and the second secondary winding Ns2 serves as the secondary winding of the transformer. At this time, the transformer turn ratio is In the second operation mode, the primary side leakage inductance of the corresponding transformer is Lk2, and generally, Lk2>Lk1.

[0045] It should be understood that the resonant frequency of the DC-DC conversion circuit is , wherein Lr is the resonant inductance. The compensation inductance .

[0046] In the first operation mode, the compensation inductance is connected in the DC-DC conversion circuit, and the resonant inductance Lr is the primary side leakage inductance and the primary side equivalent inductance of the compensation inductance , that is, .

[0047] In the second operation mode, no compensation inductance is connected in the DC-DC conversion circuit, and the resonant inductance Lr is the leakage inductance of the transformer, that is, Lr=Lk2.

[0048] Therefore, in the first operation mode and the second operation mode, the resonant inductance Lr is unchanged, and when the secondary winding is switched, the resonant frequency of the DC-DC conversion circuit always remains unchanged, and is . In this way, the DC-DC conversion circuit realizes that the resonant parameters remain unchanged when the multiple windings are switched, and further, the DC-DC conversion circuit can realize full-range high-efficiency conversion.

[0049] As shown in Figure 2 , in the second embodiment, the secondary resonant conversion circuit further includes a second resonant circuit, the branch in which the compensation inductance is connected is defined as a first branch, and the branches other than the first branch in the multiple branches are defined as second branches, and the two ends of the second resonant circuit are connected in series between each second branch and the second rectifier inverter unit.

[0050] Specifically, the second resonant circuit comprises a second resonant inductor Lrs and a second resonant capacitor Crs, and the second secondary winding NS2, the second resonant inductor Lrs and the second resonant capacitor Crs are connected in series.

[0051] The working principle of the DC-DC conversion circuit in the embodiment is similar to that in the first embodiment, and the difference is that the DC-DC conversion circuit in the embodiment is a CLLC bidirectional conversion circuit, and thus the working principle of the second embodiment is not described herein.

[0052] As shown in the third embodiment, a DC-DC conversion circuit is provided, comprising a transformer, a primary side resonant conversion circuit and a secondary side resonant conversion circuit; Figure 3

[0053] The transformer comprises a plurality of primary windings and a plurality of secondary windings connected in series, and each primary winding is magnetically coupled with each secondary winding;

[0054] The primary side resonant conversion circuit comprises a first rectifier inverter unit, a first resonant circuit, at least one compensation inductor, and a switching unit corresponding to each primary winding; each primary winding is connected in series with the corresponding switching unit to form a corresponding branch, and each compensation inductor is connected in series in a branch; the first rectifier inverter unit is configured to convert a received primary side direct current signal into a primary side alternating current signal to a first end of the first resonant circuit; a second end of the first resonant circuit is electrically connected to a first end of the plurality of branches; and a second end of the plurality of branches is electrically connected to the first rectifier inverter unit.

[0055] The secondary side resonant conversion circuit comprises a second rectifier inverter unit, and each secondary winding is configured to output a secondary side alternating current signal to the second rectifier inverter unit; and the second rectifier inverter unit is configured to convert the secondary side alternating current signal into a secondary side direct current signal.

[0056] Further, the number of compensation inductors is less than the number of primary windings.

[0057] In the embodiment, a DC-DC conversion circuit with mixed winding switching and series-parallel switching is exemplified. Specifically, the primary side resonant conversion circuit comprises a first rectifier inverter unit, a first resonant circuit, a compensation inductor Lcp, a first switching unit K1 and a second switching unit K2; the transformer comprises two primary windings and two secondary windings, each primary winding is connected in series with the first switching unit K1 and the second switching unit K2 to form a corresponding branch, and the compensation inductor Lcp is connected in series with the first switching unit K1.

[0058] The secondary side resonant conversion circuit comprises two second rectifier inverter units, and the two second rectifier inverter units are connected in parallel to the two secondary windings.

[0059] ​The third embodiment has similar working principle to the first embodiment. Similarly, the DC-DC conversion circuit in the third embodiment also includes two working modes. When one of the first switch unit K1 and the second switch unit K2 is closed, the other one is opened, so as to realize winding switching of the DC-DC conversion circuit. Meanwhile, the compensation inductor Lcp can realize compensation of the resonant parameters in the working mode in which the first switch unit K1 is closed. Since the working principle is similar to the first embodiment, details are not described herein.

[0060] It can be understood that the DC-DC conversion circuit provided by the utility model can also be applied to a three-phase resonant circuit. Specifically, referring to Figure 4 In the fourth embodiment, the DC-DC conversion circuit includes a transformer, a primary resonant conversion circuit and a secondary resonant conversion circuit.

[0061] The transformer includes a plurality of primary windings and a plurality of secondary windings. The primary windings are magnetically coupled to the secondary windings. The plurality of secondary windings are connected in series to form a plurality of third secondary windings. Specifically, as shown in Figure 4 The secondary winding N2 and the secondary winding N3 are connected in series to form a group of third secondary windings. The transformer includes a plurality of groups of third secondary windings formed by the secondary windings N2 and N3.

[0062] The primary resonant conversion circuit includes a first rectifier-inverter unit and a first resonant circuit corresponding to the plurality of primary windings. The first rectifier-inverter unit is used to convert the received primary direct current signal into a primary alternating current signal to the first end of the first resonant circuit. The second end of the first resonant circuit is electrically connected to the first end of the primary winding. The second ends of the primary windings are electrically connected.

[0063] The secondary resonant conversion circuit includes a compensation inductor, a second rectifier-inverter unit and a plurality of switch units corresponding to the third secondary windings. In each third secondary winding, two secondary windings are connected in series with the corresponding switch unit to form a corresponding branch. A compensation inductor is connected in series with a branch.

[0064] The branch with the compensation inductor in the plurality of branches is defined as the first branch. The branch other than the first branch in the plurality of branches is defined as the second branch. The plurality of first branches are connected in parallel. The plurality of second branches are connected in parallel.

[0065] Each branch is used to output a secondary alternating current signal to the second rectifier-inverter unit. The second rectifier-inverter unit is used to convert the secondary alternating current signal into a secondary direct current signal.

[0066] It can be understood that the working principle of the DC-DC conversion circuit in the fourth embodiment is still similar to that of the DC-DC conversion circuit in the first embodiment. Specifically, as shown in Figure 4As shown, the switch units K1 and K2 are closed or opened simultaneously, the switch units K3 and K4 are closed or opened simultaneously, the switch units K1 and K2 are closed while the switch units K3 and K4 are opened, the switch units K1 and K2 are opened while the switch units K3 and K4 are closed, thus realizing the winding switching of the DC-DC conversion circuit in the embodiment.

[0067] It should be noted that the embodiment is only a preferred embodiment, and the switch units in the first to fifth embodiments are not limited to the number and type shown, and those skilled in the art can select appropriate switch units according to actual application requirements. In some embodiments, the switch unit can be a mechanical switch, a semiconductor switch, or a combination circuit composed of at least one mechanical switch and at least one semiconductor switch in parallel. Those skilled in the art can select appropriate mechanical switches and semiconductor switches according to actual application requirements, such as: the mechanical switch can be selected as a single-pole single-throw switch, and the semiconductor switch can be selected as MOS or IGBT, etc.

[0068] In addition, in the embodiment, the secondary winding is used to output a secondary alternating current signal to the second rectifier-inverter unit, and the second rectifier-inverter unit is used to convert the secondary alternating current signal into a secondary direct current signal. It can be understood that the above-mentioned preferred scheme of the plurality of secondary windings in series is provided in the plurality of embodiments, and the plurality of secondary windings can be connected in series or in parallel.

[0069] The second aspect of the embodiment provides a DC-DC converter, which includes the DC-DC conversion circuit as described above.

[0070] The third aspect of the embodiment further provides a charging module, which includes the DC-DC converter as described above.

[0071] The charging module includes at least one DC-DC converter, and a plurality of DC-DC converters can form a charging module in series or in parallel. In actual application, a plurality of charging modules can also be combined in series or in parallel.

[0072] The second aspect and the third aspect of the embodiment are described in the first part of the embodiment, and have corresponding descriptions corresponding to other parts of the embodiment, which can produce similar technical effects, and will not be described here.

[0073] The above only describes preferred embodiments of the utility model, and does not limit the utility model, and any modification, equivalent replacement and improvement made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A DC-DC conversion circuit, characterized by comprising: The transformer comprises at least one primary winding and a plurality of secondary windings in series, the primary winding is magnetically coupled with each of the secondary windings; The transformer comprises at least one primary winding and a plurality of secondary windings in series, the primary winding is magnetically coupled with each of the secondary windings; The primary resonant conversion circuit comprises a first rectifier-inverter unit and a first resonant circuit; the first rectifier-inverter unit is configured to convert a received primary direct-current signal into a primary alternating-current signal to a first end of the first resonant circuit; a second end of the first resonant circuit is electrically connected to a first end of the primary winding; and a second end of the primary winding is electrically connected to the first rectifier-inverter unit; The secondary resonant conversion circuit comprises at least one compensation inductor, a second rectifier-inverter unit, and a plurality of switch units corresponding to the plurality of secondary windings; each of the secondary windings is connected in series with a corresponding switch unit to form a corresponding branch; at least one of the branches is connected in series with the compensation inductor; each of the branches is configured to output a secondary alternating-current signal to the second rectifier-inverter unit; and the second rectifier-inverter unit is configured to convert the secondary alternating-current signal into a secondary direct-current signal.

2. The DC-DC conversion circuit according to claim 1, characterized by, The number of compensation inductors is less than the number of secondary windings.

3. The DC-DC conversion circuit according to claim 2, characterized by The transformer comprises two secondary windings in series; the secondary resonant conversion circuit comprises one compensation inductor and two switch units corresponding to the two secondary windings; the two secondary windings are connected in series with corresponding switch units to form corresponding branches; and the compensation inductor is connected in series with one of the branches.

4. The DC-to-DC conversion circuit of claim 1, wherein, The secondary resonant conversion circuit further comprises a second resonant circuit; the branch in which the compensation inductor is connected is defined as a first branch; and branches other than the first branch among the plurality of branches are defined as second branches; and two ends of the second resonant circuit are connected in series between one of the second branches and the second rectifier-inverter unit.

5. A DC-DC conversion circuit, characterized by comprising: The transformer comprises at least one primary winding and a plurality of secondary windings in series, the primary winding is magnetically coupled with each of the secondary windings; The transformer comprises a plurality of primary windings and a plurality of secondary windings; each of the primary windings is magnetically coupled with each of the secondary windings; The primary resonant conversion circuit comprises a first rectifier-inverter unit, a first resonant circuit, at least one compensation inductor, and a plurality of switch units corresponding to the plurality of primary windings; each of the primary windings is connected in series with a corresponding switch unit to form a corresponding branch; each of the compensation inductors is connected in series with one of the branches; the first rectifier-inverter unit is configured to convert a received primary direct-current signal into a primary alternating-current signal to a first end of the first resonant circuit; a second end of the first resonant circuit is electrically connected to first ends of the plurality of branches; and second ends of the plurality of branches are electrically connected to the first rectifier-inverter unit; The secondary resonant conversion circuit comprises a second rectifier-inverter unit; the plurality of secondary windings are configured to output a secondary alternating-current signal to the second rectifier-inverter unit; and the second rectifier-inverter unit is configured to convert the secondary alternating-current signal into a secondary direct-current signal.

6. The DC-DC conversion circuit according to claim 5, wherein The number of compensation inductors is less than the number of primary windings.

7. A DC-DC converter, characterized by The DC-DC conversion circuit comprises any one of the DC-DC conversion circuits according to claims 1 to 6.

8. A charging module, characterized by The DC-DC converter comprises the DC-DC conversion circuit according to claim 7.

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