Bidirectional DCDC converter and power conversion module

Abstract

The utility model provides a bidirectional DCDC converter and a power conversion module, and relates to the technical field of power supply. The bidirectional DCDC converter comprises a first bridge circuit, a first resonance module, a transformer, a second resonance module and a second bridge circuit, the transformer comprises a primary side and a secondary side, the first bridge circuit is connected with the first resonance module and the first end of the primary side, the first resonance module is connected with the second end of the primary side, and the second resonance module is connected with the second end of the secondary side. The second bridge circuit is respectively connected with the second resonance module and the first end of the secondary side, and the second resonance module is connected with the second end of the secondary side; when the power flow flows in the forward direction, the first resonance module is connected, the second resonance module is disconnected, and the first resonance module and the transformer form an LLC topology. When the power flow flows in the reverse direction, the second resonance module is connected, the first resonance module is turned off, and the second resonance module and the transformer form an LLC topology. The utility model has the advantages of wide output range and high efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of power supply, and more particularly, to a bidirectional DCDC converter and a power conversion module. Background Art

[0002] Currently, electric vehicles have become the main development direction in the automotive field. The rise of electric vehicles has brought new technical challenges to the field of power electronics.

[0003] The V2G technology (Vehicle to Grid) of electric vehicles refers to the technology of electric vehicles feeding power to the grid. Its core idea is to use the power batteries of a large number of electric vehicles as a buffer between the grid and renewable energy. The technology of electric vehicles discharging power to the grid is receiving extensive attention because through the V2G technology, not only can the problems of low grid efficiency and fluctuations in renewable energy be greatly alleviated, but also benefits can be created for electric vehicle users.

[0004] The core of the V2G technology lies in the bidirectional isolated DCDC converter, but the existing bidirectional isolated DCDC converters have problems such as a small gain range, low efficiency, or complex structure. Summary of the Utility Model

[0005] The purpose of the present application is to provide a bidirectional DCDC converter and a power conversion module to solve the problems of a small gain range or low efficiency existing in the bidirectional isolated DCDC converter in the prior art.

[0006] To achieve the above purpose, the technical solutions adopted in the embodiments of the present application are as follows:

[0007] On the one hand, the embodiments of the present application provide a bidirectional DCDC converter. The bidirectional DCDC converter includes a first bridge circuit, a first resonant module, a transformer, a second resonant module, and a second bridge circuit. The transformer includes a primary side and a secondary side. The first bridge circuit is respectively connected to the first resonant module and the first end of the primary side. The first resonant module is connected to the second end of the primary side. The second bridge circuit is respectively connected to the second resonant module and the first end of the secondary side. The second resonant module is connected to the second end of the secondary side. Wherein,

[0008] When the power flow is in the forward direction, the first resonant module is connected, the second resonant module is turned off, and the first resonant module and the transformer form an LLC topology.

[0009] When the power flow is in the reverse direction, the second resonant module is connected, the first resonant module is turned off, and the second resonant module and the transformer form an LLC topology.

[0010] Optionally, the first resonant module includes a first resonant inductor, a first resonant capacitor, and a first switching switch. One end of the series connection of the first resonant inductor and the first resonant capacitor is connected to the first bridge circuit, and the other end is connected to the first end of the primary side. The first switching switch is connected in parallel with the first resonant inductor and the first resonant capacitor;

[0011] When the power flow is in the forward direction, the first switching switch is turned off;

[0012] When the power flow is in the reverse direction, the first switching switch is turned on.

[0013] Optionally, the second resonant module includes a second resonant inductor, a second resonant capacitor, and a second switching switch. The first end of the series connection of the second resonant inductor and the second resonant capacitor is connected to the second bridge circuit, and the second end is connected to the first end of the secondary side. The second switching switch is connected in parallel with the second resonant inductor and the second resonant capacitor;

[0014] When the power flow is in the forward direction, the second switching switch is turned on;

[0015] When the power flow is in the reverse direction, the second switching switch is turned off.

[0016] Optionally, the first bridge circuit is a full-bridge circuit, and the second bridge circuit is a half-bridge circuit; or the first bridge circuit is a half-bridge circuit, and the second bridge circuit is a full-bridge circuit.

[0017] Optionally, both the first bridge circuit and the second bridge circuit are full-bridge circuits, or both the first bridge circuit and the second bridge circuit are half-bridge circuits.

[0018] Optionally, the half-bridge circuit includes a first bridge arm and a first capacitor assembly. The two ends of the first bridge arm and the first capacitor assembly are used to connect to a first power supply.

[0019] Optionally, the first capacitor assembly includes a first capacitor and a second capacitor with equal capacitance values. The two ends of the series connection of the first capacitor and the second capacitor are used to connect to a first power supply. The middle node of the first capacitor and the second capacitor is connected to the first end of the primary side, or the middle node of the first capacitor and the second capacitor is connected to the first resonant module.

[0020] Optionally, the full-bridge circuit includes a first bridge arm and a second bridge arm. The two ends of the first bridge arm and the second bridge arm are used to connect to the positive and negative poles of a first power supply or a second power supply.

[0021] Optionally, the bidirectional DCDC converter further includes a first bus capacitor and a second bus capacitor. The first bus capacitor is connected in parallel with the first bridge circuit, and the second bus capacitor is connected in parallel with the second bridge circuit.

[0022] On the other hand, an embodiment of the present application further provides a power conversion module, which includes the above-mentioned bidirectional DCDC converter.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The present application provides a bidirectional DCDC converter and a power conversion module. The bidirectional DCDC converter includes a first bridge circuit, a first resonant module, a transformer, a second resonant module, and a second bridge circuit. The transformer includes a primary side and a secondary side. The first bridge circuit is respectively connected to the first resonant module and the first end of the primary side. The first resonant module is connected to the second end of the primary side. The second bridge circuit is respectively connected to the second resonant module and the first end of the secondary side. The second resonant module is connected to the second end of the secondary side. Among them, when the power flow is flowing in the forward direction, the first resonant module is connected, the second resonant module is turned off, and the first resonant module and the transformer form an LLC topology. When the power flow is flowing in the reverse direction, the second resonant module is connected, the first resonant module is turned off, and the second resonant module and the transformer form an LLC topology. Since in the bidirectional DCDC converter provided by the present application, whether the power flow is flowing in the forward direction or the reverse direction, an LLC topology can be formed, thereby improving the step-up / step-down gain range of the entire bidirectional DCDC converter. And, whether the power flow is flowing in the forward direction or the reverse direction, only one resonant module is always connected, so no extra power consumption is generated in the entire bidirectional DCDC converter, and the efficiency is improved.

[0025] To make the above objects, features, and advantages of the present application more obvious and understandable, the following specific preferred embodiments are given below and are described in detail in conjunction with the accompanying drawings as follows. Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts.

[0027] Figure 1 It is the first circuit schematic diagram of the bidirectional DCDC converter provided by the embodiment of the present application.

[0028] Figure 2 It is the second circuit schematic diagram of the bidirectional DCDC converter provided by the embodiment of the present application.

[0029] Figure 3 For the embodiment of the present application Figure 1 Schematic diagram of the equivalent circuit of the bidirectional DCDC converter when the power flow is flowing forward.

[0030] Figure 4 For the embodiment of the present application Figure 1 Schematic diagram of the equivalent circuit of the bidirectional DCDC converter when the power flow is flowing backward.

[0031] Figure 5 For the embodiment of the present application Figure 2 Schematic diagram of the equivalent circuit of the bidirectional DCDC converter when the power flow is flowing forward.

[0032] Figure 6 For the embodiment of the present application Figure 2 Schematic diagram of the equivalent circuit of the bidirectional DCDC converter when the power flow is flowing backward.

[0033] Figure 7 The third circuit schematic diagram of the bidirectional DCDC converter provided for the embodiment of the present application.

[0034] Figure 8 The fourth circuit schematic diagram of the bidirectional DCDC converter provided for the embodiment of the present application.

[0035] In the figure:

[0036] 110 - First bridge circuit; 120 - First resonant module; 130 - Transformer; 140 - Second resonant module; 150 - Second bridge circuit. Lr1 - First resonant inductor; Lr2 - Second resonant inductor; Cr1 - First resonant capacitor; Cr2 - Second resonant capacitor; S1 - First switching switch; S2 - Second switching switch; Q1 - First power transistor; Q2 - Second power transistor; Q3 - Third power transistor; Q4 - Fourth power transistor; Q5 - Fifth power transistor; Q6 - Sixth power transistor; Q7 - Seventh power transistor; Q8 - Eighth power transistor; C1 - First capacitor; C2 - Second capacitor; C3 - Third capacitor; C4 - Fourth capacitor. Detailed implementation manners

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. The components of the embodiments of the present application described and illustrated in the drawings here can be arranged and designed in various different configurations.

[0038] Accordingly, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but merely represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the scope of protection of the present application.

[0039] It should be noted that like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of the present application, terms such as "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0040] It should be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0041] The following will describe in detail some embodiments of the present application in conjunction with the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments may be combined with each other.

[0042] As described in the background art, currently, two-way isolated DCDC converters generally have problems such as a small gain range or low efficiency.

[0043] Among them, by adding an LLC resonant circuit to the two-way DCDC converter, the effect of improving the buck-boost gain range can be achieved. Specifically, the role of the LLC resonant circuit in the two-way DCDC converter is mainly reflected in improving efficiency and power density, while optimizing the power supply design. The LLC resonant circuit controls the switching frequency to keep the output voltage constant, achieving zero-voltage switching (ZVS) of the two main MOS switches on the primary side and zero-current switching (ZCS) of the rectifier diode on the secondary side. This soft-switching technology can significantly reduce the switching losses of the power supply, thereby improving the efficiency and power density of the power circuit. In addition, due to its resonant characteristics, the LLC resonant circuit can maintain high efficiency even at very high powers, while realizing the soft-switching functions on the primary and secondary sides, further reducing the switching losses and improving the overall efficiency. This circuit also allows for a higher switching frequency and reduces the switching losses, so it is more suitable for high-power and high-efficiency applications.

[0044] Currently, a method of using a single LLC resonant circuit is generally adopted in two-way isolated DCDC converters. When using a single LLC resonant circuit, for example, the LLC resonant circuit is arranged to be connected to the primary side of the transformer, while the secondary side of the transformer is not connected to the LLC resonant circuit. On this basis, according to the input-output voltage ratio formula:

[0045] K rate = M ac * N;

[0046] Wherein, K rate represents the input-output voltage ratio of the entire DCDC converter, N represents the turn ratio of the transformer, and M ac represents the voltage ratio of the resonant network. The voltage ratio of the resonant network can be adjusted by the resonant frequency of LLC.

[0047] It can be seen that when the LLC resonant circuit is arranged on the primary side of the transformer and not on the secondary side, if the power flow is in the forward direction, the input-output voltage ratio can be adjusted by adjusting the resonant frequency of LLC, so that the gain range is wider, and then a wide-range output of the DCDC converter is realized. However, when the power flow is in the reverse direction, since the LLC resonant circuit is not arranged on the secondary side of the transformer, the input-output voltage ratio cannot be adjusted by adjusting the resonant frequency, and the gain range of the DCDC converter is narrow, resulting in a narrow output range.

[0048] Therefore, for the method of arranging the LLC resonant circuit on only one side of the transformer, a wide-range voltage output cannot be realized.

[0049] However, if the LLC resonant circuit is arranged on both sides of the transformer, although a wide-range output can be realized when the power flow is in the forward or reverse direction, due to the increase of devices, the power consumption will increase, and then the efficiency of the entire DCDC converter will decrease.

[0050] For example, when the power flow is in the forward direction, the resonant circuit connected to the secondary side of the transformer will generate high power consumption; when the power flow is in the reverse direction, the resonant circuit connected to the primary side of the transformer will generate high power consumption.

[0051] Therefore, the existing bidirectional isolation type DCDC converter has problems of small output range or low efficiency.

[0052] In view of this, to solve the above problems, the present application provides a bidirectional DCDC converter. As an implementation, please refer to Figure 1, the bidirectional DCDC converter includes a first bridge circuit 110, a first resonant module 120, a transformer 130, a second resonant module 140, and a second bridge circuit 150. The transformer 130 includes a primary side and a secondary side. The first bridge circuit 110 is respectively connected to the first resonant module 120 and the first end of the primary side. The first resonant module 120 is connected to the second end of the primary side. The second bridge circuit 150 is respectively connected to the second resonant module 140 and the first end of the secondary side. The second resonant module 140 is connected to the second end of the secondary side. Wherein, when the power flow is in the forward direction, the first resonant module 120 is connected, the second resonant module 140 is turned off, and the first resonant module 120 and the transformer 130 form an LLC topology. When the power flow is in the reverse direction, the second resonant module 140 is connected, the first resonant module 120 is turned off, and the second resonant module 140 and the transformer 130 form an LLC topology.

[0053] In the bidirectional DCDC converter provided by the present application, on the one hand, by setting the first resonant module 120 and the second resonant module 140, a wide-range voltage output can be achieved whether the power flow is in the forward or reverse direction. On the other hand, whether the power flow is in the forward or reverse direction, only one resonant module always forms an LLC topology with the transformer 130, while the other resonant module is in the off state, so no extra power consumption will be generated, and the efficiency of the entire bidirectional DCDC converter is higher.

[0054] It should be noted that, as Figure 1 shown, in the present application, the left side of the transformer 130 is defined as the primary side, and the right side of the transformer 130 is defined as the secondary side. The first bridge circuit 110 is connected to the first power supply (i.e., Vbus in the figure) through a bus, and the second bridge circuit 150 is connected to the second power supply (i.e., Vbat in the figure) through a bus. On this basis, the forward flow of the power flow described in the present application means that the power flow flows from Vbus to Vbat; the reverse flow described in the present application means that the power flow flows from Vbat to Vbus.

[0055] The specific circuit of the present application will be described below:

[0056] As an implementation manner, both the first bridge circuit and the second bridge circuit are full-bridge circuits, or both the first bridge circuit and the second bridge circuit are half-bridge circuits. In another implementation manner, among the first bridge circuit and the second bridge circuit, one is a full-bridge circuit and the other is a half-bridge circuit.

[0057] In the first implementation manner, please continue to refer to Figure 1, both the first bridge circuit and the second bridge circuit are full-bridge circuits. Among them, the first bridge circuit 110 includes a first bridge arm and a second bridge arm. The two ends of the first bridge arm and the second bridge arm are used to connect the positive and negative poles of the first power supply. The middle node of the first bridge arm is connected to the first resonant module, and the middle node of the second bridge arm is connected to the first end of the primary side. The second bridge circuit 150 includes a third bridge arm and a fourth bridge arm. The two ends of the third bridge arm and the fourth bridge arm are used to connect the positive and negative poles of the second power supply. The middle node of the third bridge arm is connected to the second resonant module, and the middle node of the fourth bridge arm is connected to the first end of the secondary side.

[0058] Among them, the first bridge arm includes a first power transistor Q1 and a second power transistor Q2. The second bridge arm includes a third power transistor Q3 and a fourth power transistor Q4. The third bridge arm includes a fifth power transistor Q5 and a sixth power transistor Q6. The fourth bridge arm includes a seventh power transistor Q7 and an eighth power transistor Q8. Among them, the first power transistor Q1, the third power transistor Q3, the fifth power transistor Q5, and the seventh power transistor Q7 serve as the upper bridge arm, and the second power transistor Q2, the fourth power transistor Q4, the sixth power transistor Q6, and the eighth power transistor Q8 serve as the lower bridge arm. As an implementation manner, all power transistors can adopt N-type MOS transistors.

[0059] In terms of specific connection, the drains of the first power transistor Q1 and the third power transistor Q3 are connected to the positive pole of the first power supply. The source of the first power transistor Q1 is respectively connected to the drain of the second power transistor Q2 and the first resonant module 120. The source of the third power transistor Q3 is respectively connected to the drain of the fourth power transistor Q4 and the first end of the primary side. The sources of the second power transistor Q2 and the fourth power transistor Q4 are connected to the negative pole of the first power supply. The drains of the fifth power transistor Q5 and the seventh power transistor Q7 are connected to the positive pole of the second power supply. The source of the fifth power transistor Q5 is respectively connected to the drain of the sixth power transistor Q6 and the second resonant module 140. The source of the seventh power transistor Q7 is respectively connected to the drain of the eighth power transistor Q8 and the first end of the secondary side. The sources of the sixth power transistor Q6 and the eighth power transistor Q8 are connected to the negative pole of the second power supply.

[0060] It can be seen that the working principle of the bidirectional DCDC converter provided by this application is to first convert direct current into alternating current, realize the conversion of alternating current to alternating current through the transformer 130, and finally convert alternating current back into direct current.

[0061] For example, when the power flow is in the forward direction, the voltage input terminal is Vbus, and the first bridge circuit 110 acts as an inverter bridge. Then, the first bridge circuit 110 is used to convert Vbus into alternating current. The alternating current passes through the transformer 130 to achieve voltage conversion. If Vbus is the high-voltage side and Vbat is the low-voltage side, after passing through the transformer 130, the high-voltage alternating current is converted into low-voltage alternating current; if Vbus is the low-voltage side and Vbat is the high-voltage side, after passing through the transformer 130, the low-voltage alternating current is converted into high-voltage alternating current. Moreover, the second bridge circuit 150 acts as a rectifier bridge, and its function is to convert the alternating current into direct current again and output it to Vbat.

[0062] Of course, when the power flow is in the reverse direction, its working principle is similar and will not be elaborated here.

[0063] By adopting full-bridge circuits for both the first bridge circuit and the second bridge circuit, it is possible to achieve power and voltage application scenarios applicable to a wider range.

[0064] As another implementation method, both the first bridge circuit and the second bridge circuit are half-bridge circuits. In the first bridge circuit 110 and the second bridge circuit 150, each includes a bridge arm and a capacitor assembly. Among them, the first bridge circuit 110 includes a first bridge arm and a first capacitor assembly. The two ends of the first bridge arm and the first capacitor assembly are used to connect the positive and negative poles of the first power supply. The middle node of the first bridge arm is connected to the first resonant module, and the middle node of the first capacitor assembly is connected to the first end of the primary side. Of course, it can also be that the middle node of the first capacitor assembly is connected to the first resonant module, and the middle node of the first bridge arm is connected to the first end of the primary side.

[0065] The second bridge circuit 150 includes a third bridge arm and a second capacitor assembly. The two ends of the third bridge arm and the second capacitor assembly are used to connect the second power supply. The middle node of the third bridge arm is connected to the second resonant module, and the middle node of the second capacitor assembly is connected to the first end of the secondary side; or the middle node of the third bridge arm is connected to the first end of the secondary side, and the middle node of the second capacitor assembly is connected to the second resonant module.

[0066] Exemplarily, the first capacitor assembly includes a first capacitor C1 and a second capacitor C2 with equal capacitance values. The two ends after the first capacitor C1 and the second capacitor C2 are connected in series are used to connect the first power supply. The middle node of the first capacitor C1 and the second capacitor C2 is connected to the first end of the primary side, or the middle node of the first capacitor C1 and the second capacitor C2 is connected to the first resonant module. The second capacitor assembly includes a third capacitor C3 and a fourth capacitor C4 with equal capacitance values. The two ends after the first capacitor C1 and the second capacitor C2 are connected in series are used to connect the second power supply. The middle node of the first capacitor C1 and the second capacitor C2 is connected to the first end of the primary side. Or, the middle node of the first capacitor C1 and the second capacitor C2 is connected to the first resonant module.

[0067] By adopting a half - bridge circuit for both the first bridge circuit and the second bridge circuit, the use cost can be reduced and the circuit structure can be made simpler.

[0068] As an implementation method, please refer to again Figure 1 and Figure 2 , the first resonant module 120 includes a first resonant inductor Lr1, a first resonant capacitor Cr1, and a first switching switch S1. One end of the series connection of the first resonant inductor Lr1 and the first resonant capacitor Cr1 is connected to the first bridge circuit 110, and the other end is connected to the first end of the primary side. The first switching switch S1 is connected in parallel with the first resonant inductor Lr1 and the first resonant capacitor Cr1; when the power flow is flowing forward, the first switching switch S1 is turned off; when the power flow is flowing in the reverse direction, the first switching switch S1 is turned on.

[0069] The second resonant module 140 includes a second resonant inductor Lr2, a second resonant capacitor Cr2, and a second switching switch S2. The first end of the series connection of the second resonant inductor Lr2 and the second resonant capacitor Cr2 is connected to the second bridge circuit 150, and the second end is connected to the first end of the secondary side. The second switching switch S2 is connected in parallel with the second resonant inductor Lr2 and the second resonant capacitor Cr2; when the power flow is flowing forward, the second switching switch S2 is turned on; when the power flow is flowing in the reverse direction, the second switching switch S2 is turned off.

[0070] As shown in the figure, when the first switching switch S1 is turned on, the first resonant inductor Lr1 and the first resonant capacitor Cr1 are short - circuited, and the first resonant module 120 is in the off state; when the second switching switch S2 is turned on, the second resonant inductor Lr2 and the second resonant capacitor Cr2 are short - circuited, and the second resonant module 140 is in the off state.

[0071] Moreover, when the first switching switch S1 is turned off, the first resonant inductor Lr1, the first resonant capacitor Cr1, and the magnetizing inductor Lm of the transformer 130 form an LLC topology; when the second switching switch S2 is turned off, the second resonant inductor Lr2, the second resonant capacitor Cr2, and the magnetizing inductor Lm of the transformer 130 form an LLC topology.

[0072] In addition, the bidirectional DCDC converter further includes a first bus capacitor and a second bus capacitor. The first bus capacitor is connected in parallel with the first bridge circuit 110, and the second bus capacitor is connected in parallel with the second bridge circuit 150.

[0073] By setting the first bus capacitor and the second bus capacitor, effects such as smoothing voltage fluctuations and improving the efficiency of the inverter can be achieved.

[0074] Next, in combination with Figure 1 and Figure 2, a detailed description of the specific working principle of the bidirectional DCDC converter provided by this application is as follows:

[0075] When the power flow is in the forward direction, Figure 1 The equivalent circuit of the bidirectional DCDC converter in Figure 3 is shown as follows. Among them, the dotted arrow indicates the power flow direction. When Vbus passes through the first bridge circuit 110, through the coordinated use of each power tube in the first bridge circuit 110, the effect of converting DC to AC is achieved. For example, in the first cycle, the first power tube Q1 and the fourth power tube Q4 are turned on, and at the same time, the second power tube Q2 and the third power tube Q3 are turned off; in the second cycle, the second power tube Q2 and the third power tube Q3 are turned on, and at the same time, the first power tube Q1 and the fourth power tube Q4 are turned off, and the switching is continuously carried out periodically to achieve the purpose of converting DC to AC. Then, it is converted through the transformer 130 and rectified through the second bridge circuit 150 to achieve the transmission of the power flow.

[0076] Among them, since the first resonant inductor Lr1, the first resonant capacitor Cr1, and the magnetizing inductor Lm of the transformer 130 form an LLC topology, by adjusting the resonant frequency, the gain range can be adjusted to achieve a wide range of voltage outputs. And because there are no inductors, capacitors and other devices on the secondary side at this time, the power consumption is low, and the efficiency of the entire bidirectional DCDC converter is higher.

[0077] When the power flow is in the reverse direction, Figure 1 The equivalent circuit of the bidirectional DCDC converter in Figure 4 is shown as follows. Since the second resonant inductor Lr2, the second resonant capacitor Cr2, and the magnetizing inductor Lm of the transformer 130 form an LLC topology, by adjusting the resonant frequency, the gain range can be adjusted to achieve a wide range of voltage outputs. And because there are no inductors, capacitors and other devices on the primary side at this time, the power consumption is low, and the efficiency of the entire bidirectional DCDC converter is higher.

[0078] Similarly, when the power flow is in the forward direction, Figure 2 The equivalent circuit of the bidirectional DCDC converter in Figure 5As shown in the figure, where the dashed arrow indicates the power flow direction. When Vbus passes through the first bridge circuit 110, the first bridge circuit 110 realizes the conversion from DC to AC through the coordinated use of the first power transistor Q1 and the second power transistor Q2. For example, in the first cycle, the first power transistor Q1 is turned on while the second power transistor Q2 is turned off. At this time, the loop current flows as Vbus+ → the first power transistor Q1 → the primary side of the transformer → the first resonant module → the second capacitor C2 → Vbus-. In the second cycle, the second power transistor Q2 is turned on while the first power transistor Q1 is turned off, and this switching is repeated periodically. At this time, the loop current flows as Vbus+ → the first capacitor C1 → the first resonant module → the primary side of the transformer → the second power transistor Q2 → Vbus-. By continuously repeating the alternating conduction mode of the first power transistor Q1 and the second power transistor Q2, the purpose of DC-to-AC conversion is achieved. Then, through the conversion of the transformer 130 and rectification by the second bridge circuit 150, the power flow transmission is realized.

[0079] When the power flow is reversed, Figure 2 the equivalent circuit of the bidirectional DCDC converter in Figure 6 is as shown. Its working principle is similar to Figure 5 and will not be elaborated here. Since the second resonant inductor Lr2, the second resonant capacitor Cr2, and the magnetizing inductor Lm of the transformer 130 form an LLC topology, by adjusting the resonant frequency, the gain range can be adjusted to achieve a wide range of voltage outputs. And since there are no inductors, capacitors, etc. in the primary side at this time, the power consumption is low and the efficiency of the entire bidirectional DCDC converter is higher.

[0080] Of course, please refer to Figure 7 and Figure 8 . In the first bridge circuit and the second bridge circuit, one of the circuits can be a full-bridge circuit and the other can be a half-bridge circuit. Among them, Figure 7 in the circuit shown, the first bridge circuit is a full-bridge circuit and the second bridge circuit is a half-bridge circuit. In Figure 8 the circuit shown, the first bridge circuit is a half-bridge circuit and the second bridge circuit is a full-bridge circuit. The specific device structure and working principle will not be elaborated here.

[0081] It should be noted that when one of the circuits is a full-bridge circuit and the other is a half-bridge circuit, a wide range of power and voltage outputs can be achieved, and the cost of the bidirectional DCDC converter is reduced.

[0082] Based on the above implementation method, the present application also provides a power supply system, which includes the above-mentioned bidirectional DCDC converter.

[0083] In summary, the present application provides a bidirectional DCDC converter and a power conversion module. The bidirectional DCDC converter includes a first bridge circuit, a first resonant module, a transformer, a second resonant module, and a second bridge circuit. The transformer includes a primary side and a secondary side. The first bridge circuit is respectively connected to the first resonant module and the first end of the primary side. The first resonant module is connected to the second end of the primary side. The second bridge circuit is respectively connected to the second resonant module and the first end of the secondary side. The second resonant module is connected to the second end of the secondary side. Wherein, when the power flow is flowing in the forward direction, the first resonant module is connected, the second resonant module is turned off, and the first resonant module and the transformer form an LLC topology. When the power flow is flowing in the reverse direction, the second resonant module is connected, the first resonant module is turned off, and the second resonant module and the transformer form an LLC topology. Since in the bidirectional DCDC converter provided by the present application, whether the power flow is flowing in the forward direction or the reverse direction, an LLC topology can be formed, thereby the step-up / step-down gain range of the entire bidirectional DCDC converter can be improved. And, whether the power flow is flowing in the forward direction or the reverse direction, only one resonant module is always connected, so the efficiency of the entire bidirectional DCDC converter is improved.

[0084] The foregoing is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0085] For those skilled in the art, it is obvious that the present application is not limited to the details of the above-described exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present application is defined by the appended claims rather than the above description. Therefore, it is intended to include all changes falling within the meaning and scope of the equivalent elements of the claims in the present application. Any reference numerals in the claims should not be regarded as limiting the claimed rights.

Claims

1. A bidirectional DCDC converter, characterized in that, The bidirectional DCDC converter includes a first bridge circuit, a first resonant module, a transformer, a second resonant module, and a second bridge circuit. The transformer includes a primary side and a secondary side. The first bridge circuit is respectively connected to the first resonant module and the first end of the primary side. The first resonant module is connected to the second end of the primary side. The second bridge circuit is respectively connected to the second resonant module and the first end of the secondary side. The second resonant module is connected to the second end of the secondary side. Wherein, When the power flow is in the forward direction, the first resonant module is connected, the second resonant module is turned off, and the first resonant module and the transformer form an LLC topology. When the power flow is in the reverse direction, the second resonant module is connected, the first resonant module is turned off, and the second resonant module and the transformer form an LLC topology.

2. The bidirectional DCDC converter according to claim 1, wherein, The first resonant module includes a first resonant inductor, a first resonant capacitor, and a first switching switch. One end of the series connection of the first resonant inductor and the first resonant capacitor is connected to the first bridge circuit, and the other end is connected to the first end of the primary side. The first switching switch is connected in parallel with the first resonant inductor and the first resonant capacitor. When the power flow is in the forward direction, the first switching switch is turned off. When the power flow is in the reverse direction, the first switching switch is turned on.

3. The bidirectional DCDC converter according to claim 1, characterized in that The second resonant module includes a second resonant inductor, a second resonant capacitor, and a second switching switch. The first end of the series connection of the second resonant inductor and the second resonant capacitor is connected to the second bridge circuit, and the second end is connected to the first end of the secondary side. The second switching switch is connected in parallel with the second resonant inductor and the second resonant capacitor. When the power flow is in the forward direction, the second switching switch is turned on. When the power flow is in the reverse direction, the second switching switch is turned off.

4. The bidirectional DCDC converter according to claim 1, wherein The first bridge circuit is a full-bridge circuit, and the second bridge circuit is a half-bridge circuit; or the first bridge circuit is a half-bridge circuit, and the second bridge circuit is a full-bridge circuit.

5. The bidirectional DCDC converter according to claim 1, wherein Both the first bridge circuit and the second bridge circuit are full-bridge circuits, or both the first bridge circuit and the second bridge circuit are half-bridge circuits.

6. The bidirectional DCDC converter according to claim 4 or 5, wherein, The half-bridge circuit includes a first bridge arm and a first capacitor assembly. The first bridge arm and both ends of the first capacitor assembly are used to connect to a first power supply.

7. The bidirectional DCDC converter according to claim 6, characterized in that, The first capacitor assembly includes a first capacitor and a second capacitor with equal capacitance values. Both ends of the series connection of the first capacitor and the second capacitor are used to connect to a first power supply. The middle node of the first capacitor and the second capacitor is connected to the first end of the primary side, or the middle node of the first capacitor and the second capacitor is connected to the first resonant module.

8. The bidirectional DCDC converter according to claim 4 or 5, characterized in that, The full-bridge circuit includes a first bridge arm and a second bridge arm. Both ends of the first bridge arm and the second bridge arm are used to connect to the positive and negative electrodes of a first power supply or a second power supply.

9. The bidirectional DCDC converter according to claim 1, wherein, The bidirectional DCDC converter further includes a first bus capacitor and a second bus capacitor. The first bus capacitor is connected in parallel with the first bridge circuit, and the second bus capacitor is connected in parallel with the second bridge circuit.

10. A power conversion module, characterized in that, The power conversion module includes the bidirectional DCDC converter according to any one of claims 1 to 9.

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