Bidirectional DCDC converter, DC charging gun and energy storage system

Abstract

The utility model discloses a bidirectional DCDC converter and a DC charging pile, and the converter comprises a first end, a second end, at least two bidirectional DCDC units, a first switching circuit, a second switching circuit, and a controller. Each bidirectional DCDC unit comprises a transformer, a primary DCDC circuit and a primary resonance network which are sequentially connected between the first end and the primary side of the transformer, and a secondary DCDC circuit and a secondary resonance network which are sequentially connected between the second end and the secondary side of the transformer; the first switch circuit is connected between the first end and the primary DCDC circuit; the second switching circuit is connected between the second end and the secondary DCDC circuit; and the controller is configured to control the at least two primary DCDC circuits to form series connection or parallel connection, and / or control the at least two secondary DCDC circuits to form series connection or parallel connection. The bidirectional DCDC converter provided by the utility model can accept larger voltage and current without using components with larger bearing capacity, so that the device cost is effectively reduced.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and more particularly, to a bidirectional DCDC converter, a DC charging gun, and an energy storage system. Background Art

[0002] With the development of the new energy industry, the voltage range of batteries has gradually expanded. In related technologies, in order to meet the wide voltage range, it is easy to cause the output efficiency of the low-voltage side to be much lower than that of the high-voltage side. In addition, when the DCDC conversion circuit outputs the same power, the current of the DCDC conversion circuit will increase significantly when outputting at low voltage. As the current increases, the loss of power devices will increase, the power devices will heat up seriously, and it is easy to cause the burnout of power devices. To avoid burnout, the current-carrying capacity of power devices also needs to be increased, resulting in an increase in cost. Summary of the Utility Model

[0003] An embodiment of the present application provides a bidirectional DCDC converter.

[0004] The bidirectional DCDC converter according to the embodiment of the present application includes:

[0005] A first end;

[0006] A second end;

[0007] At least two bidirectional DCDC units, each of the bidirectional DCDC units including a transformer, a primary DCDC circuit and a primary resonant network connected in sequence between the first end and the primary side of the transformer, and a secondary DCDC circuit and a secondary resonant network connected in sequence between the second end and the secondary side of the transformer;

[0008] A first switch circuit connected between the first end and the primary DCDC circuit;

[0009] A second switch circuit connected between the second end and the secondary DCDC circuit;

[0010] A controller configured to control the on / off of the switches in the first switch circuit so that the primary DCDC circuits of the at least two bidirectional DCDC units are connected in series or in parallel, and / or control the on / off of the switches in the second switch circuit so that the secondary DCDC circuits of the at least two bidirectional DCDC units are connected in series or in parallel.

[0011] The bidirectional DCDC converter provided by this application controls the on and off of the switches in the first switch circuit and the second switch circuit through a controller, thereby realizing the switching between series and parallel connections of the two primary DCDC circuits and the switching between series and parallel connections of the two secondary DCDC circuits. This enables the bidirectional DCDC converter to accept a larger voltage and current while eliminating the need to use components with a higher load-carrying capacity, effectively reducing the device cost.

[0012] In some embodiments, the bidirectional DCDC converter includes a first bidirectional DCDC unit and a second bidirectional DCDC unit. The first bidirectional DCDC unit includes a first transformer, a first primary DCDC circuit and a first primary resonance network connected in sequence between the first terminal and the primary side of the first transformer, and a first secondary DCDC circuit and a first secondary resonance network connected in sequence between the second terminal and the secondary side of the first transformer.

[0013] The second bidirectional DCDC unit includes a second transformer, a second primary DCDC circuit and a second primary resonance network connected in sequence between the first terminal and the primary side of the second transformer, and a second secondary DCDC circuit and a second secondary resonance network connected in sequence between the second terminal and the secondary side of the second transformer.

[0014] In this way, setting two bidirectional DCDC units can achieve accepting a larger voltage and current while facilitating cost savings.

[0015] In some embodiments, the first switch circuit includes a first switch connected between the positive electrode of the first terminal and the second primary DCDC circuit, a second switch connected between the first primary DCDC circuit and the second primary DCDC circuit, and a third switch connected between the negative electrode of the first terminal and the first primary DCDC circuit.

[0016] The second switch circuit includes a fourth switch connected between the positive electrode of the second terminal and the second secondary DCDC circuit, a fifth switch connected between the first secondary DCDC circuit and the second secondary DCDC circuit, and a sixth switch connected between the negative electrode of the second terminal and the first secondary DCDC circuit.

[0017] In this way, by using the on and off of three switches, not only the switching between series and parallel connections of the two primary DCDC circuits is realized, but also the fewest switches are used, which is beneficial to cost savings.

[0018] In some embodiments, the first primary DCDC circuit includes a first primary full-bridge circuit and a first primary capacitor connected in parallel. Both ends of the first primary full-bridge circuit are connected to both ends of the first primary capacitor. The other two ends of the first primary full-bridge circuit are connected to two electrodes of the primary side of the first transformer. The first primary capacitor is connected to the positive and negative electrodes of the first end.

[0019] The second primary DCDC circuit includes a second primary full-bridge circuit and a second primary capacitor connected in parallel. Both ends of the second primary full-bridge circuit are connected to both ends of the second primary capacitor. The other two ends of the second primary full-bridge circuit are connected to two electrodes of the primary side of the second transformer. The second primary capacitor is connected to the positive and negative electrodes of the first end.

[0020] The first secondary DCDC circuit includes a first secondary full-bridge circuit and a first secondary capacitor connected in parallel. Both ends of the first secondary full-bridge circuit are connected to both ends of the first secondary capacitor. The other two ends of the first secondary full-bridge circuit are connected to two electrodes of the secondary side of the first transformer. The first secondary capacitor is connected to the positive and negative electrodes of the second end.

[0021] The second secondary DCDC circuit includes a second secondary full-bridge circuit and a second secondary capacitor connected in parallel. Both ends of the second secondary full-bridge circuit are connected to both ends of the second secondary capacitor. The other two ends of the second secondary full-bridge circuit are connected to two electrodes of the secondary side of the second transformer. The second secondary capacitor is connected to the positive and negative electrodes of the second end.

[0022] In this way, the first primary full-bridge circuit, the second primary full-bridge circuit, the first secondary full-bridge circuit, and the second secondary full-bridge circuit are used to achieve bidirectional current flow according to the control signal, and can also improve the reliability of the bidirectional DCDC converter.

[0023] In some embodiments, one end of the first primary capacitor is connected to the positive electrode of the first end, and the other end is respectively connected to the negative electrode of the first end through the third switch and to the second primary capacitor through the second switch.

[0024] One end of the second primary capacitor is connected to the negative electrode of the first end, and the other end is respectively connected to the positive electrode of the first end through the first switch and to the first primary capacitor through the second switch.

[0025] One end of the first secondary capacitor is connected to the positive electrode of the second end, and the other end is respectively connected to the negative electrode of the second end through the sixth switch and to the second secondary capacitor through the fifth switch.

[0026] One end of the second secondary capacitor is connected to the negative electrode of the second terminal, and the other end is respectively connected to the positive electrode of the second terminal through the fourth switch and to the first secondary capacitor through the fifth switch.

[0027] In this way, the first primary capacitor, the second primary capacitor, the first secondary capacitor, and the second secondary capacitor can be used to smooth the pulsation and noise of the output voltage, making the output voltage more stable.

[0028] In some embodiments, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and / or the sixth switch are high-frequency switching switches.

[0029] In this way, the output voltage of the high-frequency switching power supply has high stability, is not easily affected by changes in the input voltage and load, and has a higher energy conversion efficiency.

[0030] In some embodiments, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and / or the sixth switch are any one of MOS transistors, IGBTs, or relays.

[0031] In this way, selecting MOS transistors, IGBTs, or relays for the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch can be respectively applicable to different usage scenarios, which is beneficial to broadening the usage range of the bidirectional DCDC converter.

[0032] In some embodiments, the bidirectional DCDC converter further includes a voltage detection circuit, and the voltage detection circuit is connected in parallel to the first terminal and / or the second terminal.

[0033] In this way, the voltages of the first terminal and the second terminal can be detected at any time through the voltage detection circuit to avoid excessive voltage.

[0034] In some embodiments, the voltage detection circuit includes an operational amplifier and several resistors connected in series. Two input terminals of the operational amplifier are connected to both ends of any one of the resistors, and the output terminal of the operational amplifier is connected to the controller.

[0035] In this way, detecting the voltages of the first terminal and the second terminal through the operational amplifier and the controller is beneficial to reacting more promptly to problems such as excessive voltage.

[0036] In some embodiments, the voltage detection circuit includes an isolator, an operational amplifier, and several resistors connected in series. The isolator is connected in parallel to any one of the resistors, the output terminal of the isolator is connected to the operational amplifier, and the output terminal of the operational amplifier is connected to the controller.

[0037] In this way, the isolator can reduce the errors caused by signal interference and leakage, and improve the accuracy and reliability of sampling.

[0038] In some embodiments, the controller is configured to control the first switch and the third switch to be turned off and the second switch to be turned on when the voltage at the first end is greater than a predetermined voltage.

[0039] In this way, when the voltage at the first end is high, the first primary DCDC circuit and the second primary DCDC circuit at the first end form a voltage-dividing circuit to avoid damage to electrical components caused by excessive voltage.

[0040] In some embodiments, the controller is configured to control the second switch to be turned off and the first switch and the third switch to be turned on when the voltage at the first end is less than or equal to the predetermined voltage.

[0041] In this way, when the voltage at the first end is low, at this time the current at the first end is large, and the first primary DCDC circuit and the second primary DCDC circuit at the first end form a current-dividing circuit to avoid damage to electrical components caused by excessive current.

[0042] In some embodiments, the controller is configured to control the fourth switch and the sixth switch to be turned off and the fifth switch to be turned on when the voltage at the second end is greater than a predetermined voltage.

[0043] In this way, when the voltage at the second end is high, both the first secondary DCDC circuit and the second secondary DCDC circuit at the second end form a voltage-dividing circuit to avoid damage to electrical components caused by excessive voltage.

[0044] In some embodiments, the controller is configured to control the fifth switch to be turned off and the fourth switch and the sixth switch to be turned on when the voltage at the second end is less than or equal to the predetermined voltage.

[0045] In this way, when the output voltage is low, at this time the output current is large, and the first secondary DCDC circuit and the second secondary DCDC circuit at the second end form a current-dividing circuit to avoid damage to electrical components caused by excessive current.

[0046] In some embodiments, the primary resonant network includes a first capacitor and a first inductor connected in series between the primary DCDC circuit and the primary side of the transformer in sequence;

[0047] The secondary resonant network includes a second inductor and a second capacitor connected in series between the secondary DCDC circuit and the secondary side of the transformer in sequence.

[0048] In this way, the primary resonant network and the secondary resonant network can utilize the energy storage characteristics of inductors and capacitors to achieve resonance through the alternating conversion of electromagnetic energy.

[0049] A DC charging pile according to another embodiment of the present application includes:

[0050] A charging gun for connecting to an electric vehicle;

[0051] The bidirectional DCDC converter according to any one of the above, with the first end connected to the energy storage power supply system and the second end connected to the charging gun.

[0052] In some embodiments, the bidirectional DC power conversion circuit is configured such that when the energy storage power supply system charges the electric vehicle, the power flow direction of the bidirectional DC power conversion circuit is from the first end to the second end, and when the electric vehicle charges the energy storage power supply system, the power flow direction of the bidirectional DC power conversion circuit is from the second end to the first end.

[0053] In this way, the first end can be connected to the input end of the DC charging pile, and the second end can be connected to the output end of the DC charging pile.

[0054] An energy storage system according to another embodiment of the present application includes:

[0055] At least one battery pack for storing or outputting electric energy;

[0056] An inverter integrating the bidirectional DCDC converter according to any one of the above.

[0057] The additional aspects and advantages of the embodiments of the present application will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The above and / or additional aspects and advantages of the present application will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, in which:

[0059] Figure 1 is a module schematic diagram of the bidirectional DCDC converter according to an embodiment of the present application;

[0060] Figure 2 is a circuit diagram of the bidirectional DCDC converter according to an embodiment of the present application;

[0061] Figure 3 is a circuit diagram of the bidirectional DCDC converter according to an embodiment of the present application;

[0062] Figure 4It is a circuit diagram of the voltage detection circuit of the bidirectional DCDC converter in some embodiments of the present application;

[0063] Figure 5 It is a circuit diagram of the voltage detection circuit of the bidirectional DCDC converter in some embodiments of the present application.

[0064] Description of main component symbols: DC charging pile 1000, bidirectional DCDC converter 100, first end 10, second end 20, bidirectional DCDC unit 30, first bidirectional DCDC unit 31, second bidirectional DCDC unit 32, transformer 33, first transformer 331, second transformer 332, primary DCDC circuit 34, first primary DCDC circuit 341, first primary full-bridge circuit 3411, first primary capacitor 3412, second primary DCDC circuit 342, second primary full-bridge circuit 3421, second primary capacitor 3422, secondary DCDC circuit 35, first secondary DCDC circuit 351, first secondary full-bridge circuit 3511, first secondary capacitor 3512, second secondary DCDC circuit 352, second secondary full-bridge circuit 3521, second secondary capacitor 3522, primary resonance network 36, first primary resonance network 361, second primary resonance network 362, first inductor 363, first capacitor 364, secondary resonance network 37, first secondary resonance network 371, second secondary resonance network 372, second inductor 373, second capacitor 374, first switch circuit 40, first switch 41, second switch 42, third switch 43, second switch circuit 50, fourth switch 51, fifth switch 52, sixth switch 53, controller 60, voltage detection circuit 70, operational amplifier 71, resistor 72, isolator 73, charging gun 200. Specific embodiments

[0065] Embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where like or similar reference numerals denote like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary only for explaining the present application and should not be construed as limiting the present application. In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present application. In the description of the present application, "a plurality of" means two or more unless otherwise specifically defined.

[0066] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected" and "coupled" should be construed broadly. For example, it may be a fixed connection, a detachable connection, or an integral connection. It may be a mechanical connection or an electrical connection. It may be directly connected or indirectly connected through an intermediate medium, and may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0067] In the present application, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0068] The disclosure of the present application provides many different embodiments or examples for implementing different structures of the present application. To simplify the disclosure of the present application, the components and settings of specific examples are described herein. Of course, they are only examples and are not intended to limit the present application. In addition, the present application may repeat reference numerals and / or reference letters in different examples. This repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0069] With the development of the new energy industry, the voltage range of batteries has gradually expanded. In related technologies, in order to meet the wide voltage range, it is easy to cause the output efficiency of the low-voltage side to be much lower than that of the high-voltage side. In addition, when the conversion circuit outputs the same power, the current of the conversion circuit will increase significantly when the output is at a low voltage. As the current increases, the loss of the power device will increase, the power device will heat up severely, and it is easy to cause the power device to burn out. To avoid burning out, the current-carrying capacity of the power device also needs to be increased, resulting in an increase in cost.

[0070] The following explains the technical problems to be solved by the present application in the scenario of a DC charging pile to help understand the solution, but the solution is not limited to the DC charging pile and can also be used in energy storage inverters, etc.:

[0071] In the field of DC charging piles, the present application mainly solves two problems. First, it is to broaden the input voltage range that the existing DCDC converter of the DC charging pile can withstand. Second, it is to broaden the output voltage range that the existing DCDC converter of the DC charging pile can withstand, and on the premise of broadening the input voltage and output voltage ranges, maintain a high efficiency of the DCDC converter.

[0072] The following analyzes the problems existing in the existing DC charging piles. On the one hand, the input end of the DCDC converter of the existing DC charging pile is usually only connected to the grid end, and the grid voltage range is relatively narrow, such as between 380V and 800V. Therefore, the circuit design of the existing DCDC converter only needs to adapt to the grid voltage range (relatively narrow). However, with the rapid development of green energy, such as home energy storage, current users can use the energy storage battery of home energy storage to replace the grid to supply power to the DC charging pile. However, the voltage range of the energy storage battery is wider than that of the grid end. For example, it is between 150V and 1000V. Therefore, the output end of the DCDC converter of the existing DC charging pile cannot be well adapted to the energy storage battery to supply power. On the other hand, the output end of the DCDC converter of the existing DC charging pile only considers the charging voltage of electric vehicles of common models on the market, and its output voltage range is also relatively narrow. For example, it is between 200V and 500V. However, for small electric vehicles with low charging voltages (150V), such as elderly mobility scooters and low-speed electric vehicles, and large electric vehicles with high charging voltage requirements (1000V), such as electric heavy trucks, the existing DC charging piles cannot meet the requirements.

[0073] To meet the requirement that the input end can be compatible with the voltage range of the energy storage battery (wide input voltage range), and to meet the requirement that the output end can be compatible with electric vehicles with various different charging voltage ranges (wide output voltage range), a new DCDC converter of this solution is proposed.

[0074] Taking the bidirectional DC charging pile as an example, that is, the energy storage battery (input end) can charge the electric vehicle (output end) through the DC charging pile, and the electric vehicle (input end) can also charge the energy storage battery (output end) through the DC charging pile. The following analyzes the reason for the low efficiency after broadening the DCDC input and output voltage ranges. Here, the efficiency refers to the ratio of the input power to the output power. For example, if the input power of the DCDC converter is 30kW and the output power is also 29kW, then its efficiency is 29 / 30 = 96.7%. After the existing DCDC converter broadens the input and output voltage ranges, its efficiency usually becomes lower, especially when the output voltage is low, the efficiency reduction is more obvious. For example, with the same input power of 30KW, when outputting 30KW power at a high voltage of 1000V, according to P = UI, the required output current is theoretically 30A; while if outputting 30KW power at a low voltage of 300V, according to P = UI, the required output current is theoretically 100A. And power devices usually have difficulty bearing large currents, and there will be relatively large losses in the case of large currents, such as 100V. Therefore, there will be a relatively large loss in the output power when the output voltage is low. For example, here the input power is 30kW. When the output voltage is low, due to the current loss, its output power may only be 15kW, that is, the efficiency of the DCDC is only 15kW / 30kW = 50%.

[0075] To solve the problems existing in the prior art, the present application proposes a bidirectional DCDC converter and a DC charging pile, which can enable the bidirectional DCDC converter to accept larger voltages and currents while not requiring components with larger load-carrying capacities, effectively reducing the device cost. The following is a detailed description.

[0076] Please refer to Figure 1 , the present application provides a DC charging pile 1000, including a charging gun 200 and a bidirectional DCDC converter 100. The charging gun 200 is used to connect to an electric vehicle; a first end 10 is connected to an energy storage power system, and a second end 20 is connected to the charging gun 200 through the bidirectional DCDC converter 100. The bidirectional DCDC converter 100 includes a first end 10, a second end 20, at least two bidirectional DCDC units 30, a first switch circuit 40 connected between the first end 10 and the primary DCDC circuit 34, a second switch circuit 50 connected between the second end 20 and the secondary DCDC circuit 35, and a controller 60. Each bidirectional DCDC unit 30 includes a transformer 33, a primary DCDC circuit 34 and a primary resonant network 36 connected in sequence between the first end 10 and the primary side of the transformer 33, and a secondary DCDC circuit 35 and a secondary resonant network 37 connected in sequence between the second end 20 and the secondary side of the transformer 33; the first switch circuit 40 connected between the first end 10 and the primary DCDC circuit 34; the second switch circuit 50 connected between the second end 20 and the secondary DCDC circuit 35; the controller 60 is configured to control the on / off of the switches in the first switch circuit 40 to form a series or parallel connection between the primary DCDC circuits 34 of at least two bidirectional DCDC units 30, and / or control the on / off of the switches in the second switch circuit 50 to form a series or parallel connection between the secondary DCDC circuits 35 of at least two bidirectional DCDC units 30.

[0077] The bidirectional DCDC converter 100 provided by the present application realizes the switching between series and parallel connections of the two primary DCDC circuits 34 and the switching between series and parallel connections of the two secondary DCDC circuits 35 by controlling the on / off of the switches in the first switch circuit 40 and the second switch circuit 50 by the controller 60. This enables the bidirectional DCDC converter 100 to accept larger voltages and currents while not requiring components with larger load-carrying capacities, effectively reducing the device cost.

[0078] Specifically, the transformer 33 generally refers to a power electronic component that can achieve electrical isolation and voltage transformation. This transformer 33 plays an important role in the bidirectional DC converter. Through the magnetic coupling effect of its windings, the transformer 33 realizes the electrical isolation between the first terminal 10 and the second terminal 20, thereby improving the safety and reliability of the system. At the same time, it also has the ability to transform voltage. According to the turns ratio of the transformer 33 (i.e., the ratio of the number of turns of the primary winding to the number of turns of the secondary winding), the transformer 33 can transform one DC voltage into another DC voltage to meet the different requirements of the circuit, enabling the circuit to flexibly handle direct current with different voltage levels.

[0079] The primary side (also known as the primary side or input side) refers to the side directly connected to the power source, that is, the first terminal 10 of the electrical energy. The primary side is connected to the power source through wires or coils, receives electrical energy from the power source, and converts it into magnetic energy (through the magnetic field generated by the current in the wire). During the operation of the transformer 33, this magnetic energy will cross the iron core or magnetic core of the transformer 33 and be transferred to the secondary side (secondary side or output side) through mutual inductance.

[0080] The secondary side (also known as the secondary side or output side) refers to the side directly connected to the load, that is, the second terminal 20 of the electrical energy. The secondary side receives the electrical energy transferred by magnetic induction from the primary side (primary side or input side) through wires or coils, and converts it into the form of voltage and current required by the load.

[0081] Furthermore, the controller 60 is used to control the connection and disconnection of the switches in the first switch circuit 40 and the second switch circuit 50. In some embodiments, the controller 60 can be a programmable logic controller 60 (Programmable Logic Controller, PLC). The programmable logic controller 60 is a digital operation controller 60 with a microprocessor for automatic control. It uses a programmable memory to store instructions for performing operations such as logical operations, sequential control, timing, counting, and arithmetic operations inside it. These instructions control various types of mechanical equipment or production processes through digital or analog inputs and outputs. The operator can store the algorithm logic in the controller 60 in advance and control the connection and disconnection of the switches in the first switch circuit 40 and the second switch circuit 50 through the controller 60.

[0082] In other embodiments, the controller 60 can also be set to other components with the same function, which can be specifically selected according to the actual situation and will not be elaborated here.

[0083] Please refer to Figure 2 and Figure 3, in some embodiments, the bidirectional DCDC converter 100 includes a first bidirectional DCDC unit 31 and a second bidirectional DCDC unit 32. The first bidirectional DCDC unit 31 includes a first transformer 331, a first primary DCDC circuit 341 and a first primary resonant network 361 connected in sequence between the first end 10 and the primary side of the first transformer 331, and a first secondary DCDC circuit 351 and a first secondary resonant network 371 connected in sequence between the second end 20 and the secondary side of the first transformer 331;

[0084] The second bidirectional DCDC unit 32 includes a second transformer 332, a second primary DCDC circuit 342 and a second primary resonant network 362 connected in sequence between the first end 10 and the primary side of the second transformer 332, and a second secondary DCDC circuit 352 and a second secondary resonant network 372 connected in sequence between the second end 20 and the secondary side of the second transformer 332.

[0085] In this way, setting two bidirectional DCDC units 30 can achieve acceptance of larger voltages and currents, and is also beneficial to cost savings.

[0086] Specifically, in the embodiments of the present application, the first bidirectional DCDC unit 31 and the second bidirectional DCDC unit 32 are arranged in parallel. In other embodiments of the application, the bidirectional DCDC converter 100 may also have other quantities.

[0087] In some embodiments, the first switch circuit 40 includes a first switch 41 connected between the positive pole of the first end 10 and the second primary DCDC circuit 342, a second switch 42 connected between the first primary DCDC circuit 341 and the second primary DCDC circuit 342, and a third switch 43 connected between the negative pole of the first end 10 and the first primary DCDC circuit 341;

[0088] The second switch circuit 50 includes a fourth switch 51 connected between the positive pole of the second end 20 and the second secondary DCDC circuit 352, a fifth switch 52 connected between the first secondary DCDC circuit 351 and the second secondary DCDC circuit 352, and a sixth switch 53 connected between the negative pole of the second end 20 and the first secondary DCDC circuit 351.

[0089] In this way, the on-off of the three switches not only realizes the switching between series and parallel connections of the two primary DCDC circuits 34, but also uses the fewest switches, which is beneficial to cost savings.

[0090] Specifically, in the embodiments of the present application, each switching circuit is provided with three switches. Among them, when the first switch 41 and the third switch 43 are closed and the second switch 42 is open, the first primary DCDC circuit 341 and the second primary DCDC circuit 342 can be connected in parallel. When the first switch 41 and the third switch 43 are open and the second switch 42 is closed, the first primary DCDC circuit 341 and the second primary DCDC circuit 342 can be connected in series. Similarly, when the fourth switch 51 and the sixth switch 53 are closed and the fifth switch 52 is open, the first secondary DCDC circuit 351 and the second secondary DCDC circuit 352 can be connected in parallel. When the fourth switch 51 and the sixth switch 53 are open and the fifth switch 52 is closed, the first secondary DCDC circuit 351 and the second secondary DCDC circuit 352 can be connected in series.

[0091] In other embodiments, each switching circuit may also be provided with other numbers of switches for controlling the switching between series and parallel connections of the first primary DCDC circuit 341 and the second primary DCDC circuit 342 and the switching between series and parallel connections of the first secondary DCDC circuit 351 and the second secondary DCDC circuit 352.

[0092] Please refer to Figure 2 and Figure 3 , in some embodiments, the first primary DCDC circuit 341 includes a first primary full-bridge circuit 3411 and a first primary capacitor 3412 connected in parallel. The two ends of the first primary full-bridge circuit 3411 are connected to the two ends of the first primary capacitor 3412. The other two ends of the first primary full-bridge circuit 3411 are connected to the two electrodes of the primary side of the first transformer 331. The first primary capacitor 3412 is connected to the positive and negative electrodes of the first terminal 10;

[0093] The second primary DCDC circuit 342 includes a second primary full-bridge circuit 3421 and a second primary capacitor 3422 connected in parallel. The two ends of the second primary full-bridge circuit 3421 are connected to the two ends of the second primary capacitor 3422. The other two ends of the second primary full-bridge circuit 3421 are connected to the two electrodes of the primary side of the second transformer 332. The second primary capacitor 3422 is connected to the positive and negative electrodes of the first terminal 10;

[0094] The first secondary DCDC circuit 351 includes a first secondary full-bridge circuit 3511 and a first secondary capacitor 3512 connected in parallel. The two ends of the first secondary full-bridge circuit 3511 are connected to the two ends of the first secondary capacitor 3512. The other two ends of the first secondary full-bridge circuit 3511 are connected to the two electrodes of the secondary side of the first transformer 331. The first secondary capacitor 3512 is connected to the positive and negative electrodes of the second terminal 20;

[0095] The second secondary DCDC circuit 352 includes a second secondary full-bridge circuit 3521 and a second secondary capacitor 3522 connected in parallel. Both ends of the second secondary full-bridge circuit 3521 are connected to both ends of the second secondary capacitor 3522. The other two ends of the second secondary full-bridge circuit 3521 are connected to two electrodes of the secondary side of the second transformer 332. The second secondary capacitor 3522 is connected to the positive and negative poles of the second terminal 20.

[0096] In this way, the first primary full-bridge circuit 3411, the second primary full-bridge circuit 3421, the first secondary full-bridge circuit 3511, and the second secondary full-bridge circuit 3521 are used to achieve bidirectional current flow according to the control signal, and can also improve the reliability of the bidirectional DCDC converter.

[0097] Specifically, the full-bridge circuit is a circuit structure composed of four switching tubes (usually MOSFETs or IGBTs). These switching tubes are connected in a bridge mode and can achieve DC-DC or DC-AC conversion. In the DCDC circuit, the full-bridge circuit is mainly used to achieve voltage step-up and step-down conversion and bidirectional current flow. When the four switching tubes perform switching operations according to a specific timing sequence, the direction of energy flow can be controlled, thereby realizing bidirectional power conversion.

[0098] The full-bridge circuit can realize the conversion from the input voltage to the output voltage by controlling the on and off of the switching tubes, including boosting, bucking, or keeping the voltage unchanged. In the bidirectional DC power conversion circuit, the full-bridge circuit allows current to flow bidirectionally between the input and output, realizing bidirectional energy transmission. By optimizing the switching timing and duty cycle of the switching tubes, a higher conversion efficiency can be achieved and energy loss can be reduced.

[0099] Please refer to Figure 3 , in some embodiments, one end of the first primary capacitor 3412 is connected to the positive pole of the first terminal 10, and the other end is respectively connected to the negative pole of the first terminal 10 through the third switch 43 and connected to the first primary capacitor 3412 through the second switch 42;

[0100] One end of the second primary capacitor 3422 is connected to the negative pole of the first terminal 10, and the other end is respectively connected to the positive pole of the first terminal 10 through the first switch 41 and connected to the first primary capacitor 3412 through the second switch 42;

[0101] One end of the first secondary capacitor 3512 is connected to the positive pole of the second terminal 20, and the other end is respectively connected to the negative pole of the second terminal 20 through the sixth switch 53 and connected to the second secondary capacitor 3522 through the fifth switch 52;

[0102] One end of the second secondary capacitor 3522 is connected to the negative electrode of the second terminal 20, and the other end is respectively connected to the positive electrode of the second terminal 20 through the fourth switch 51 and connected to the first secondary capacitor 3512 through the fifth switch 52.

[0103] In this way, the first primary capacitor 3412, the second primary capacitor 3422, the first secondary capacitor 3512, and the second secondary capacitor 3522 can be used to smooth the pulsation and noise of the output voltage, making the output voltage more stable.

[0104] Specifically, during the off period of the switching transistor, the first primary capacitor 3412, the second primary capacitor 3422, the first secondary capacitor 3512, and the second secondary capacitor 3522 can store energy, providing a continuous current supply for the load. Using a capacitor at the first terminal 10 can filter out high-frequency noise and interference in the input voltage.

[0105] In some embodiments, the first switch 41, the second switch 42, the third switch 43, the fourth switch 51, the fifth switch 52, and / or the sixth switch 53 are high-frequency switching switches.

[0106] In this way, the output voltage of the high-frequency switching power supply has high stability, is not easily affected by changes in the input voltage and load, and has a higher energy conversion efficiency.

[0107] Specifically, in the embodiments of the present application, the first switch 41, the second switch 42, the third switch 43, the fourth switch 51, the fifth switch 52, and the sixth switch 53 are all high-frequency switches. A high-frequency switch is an electronic device based on electronic components, characterized by using a high frequency for switching control of current. Specifically, a high-frequency switch controls the flow of current in the circuit by periodically switching the current to make it quickly convert at a high frequency.

[0108] It is easy to understand that the high-frequency switch can complete the opening and closing actions in an extremely short time, thereby achieving rapid control and conversion of electrical energy in the resonant network. This rapid energy conversion helps to improve the overall efficiency of the system. In the bidirectional DCDC converter 100, the load and power supply states may change frequently. The high-frequency switch can quickly respond to these changes, adjust the working state of the circuit by short-circuiting the resonant network to meet the new load or power supply requirements.

[0109] In other embodiments, the first switch 41, the second switch 42, the third switch 43, the fourth switch 51, the fifth switch 52, and the sixth switch 53 can also be set to other non-high-frequency switches, which can be specifically selected and used according to actual needs, and will not be elaborated here. However, it should be noted that the switching frequency of non-high-frequency switches is relatively low. Therefore, when designing the circuit, appropriate values need to be selected according to the switching frequency range of non-high-frequency switches. The relatively low switching frequency may affect the response speed and efficiency of the circuit, so comprehensive consideration is required.

[0110] In some embodiments, the first switch 41, the second switch 42, the third switch 43, the fourth switch 51, the fifth switch 52, and / or the sixth switch 53 is any one of an MOS transistor, an IGBT, or a relay.

[0111] In this way, selecting an MOS transistor, an IGBT, or a relay for the first switch 41, the second switch 42, the third switch 43, the fourth switch 51, the fifth switch 52, and the sixth switch 53 can be respectively applicable to different usage scenarios, which is beneficial to broadening the usage range of the bidirectional DCDC converter 100.

[0112] Specifically, the first switch 41, the second switch 42, the third switch 43, the fourth switch 51, the fifth switch 52, and the sixth switch 53 can be selected as any one or two of an MOS transistor, an IGBT, or a relay.

[0113] It should be noted that an MOS transistor has a high input impedance and a low on-resistance, so the power consumption is very low in the switching state. And the MOS transistor has an extremely high switching speed and can work in a high-frequency environment. In addition, the MOS transistor is controlled to conduct and turn off through the gate voltage, and the control signal is simple and easy to implement.

[0114] The IGBT combines the advantages of MOSFET and bipolar transistors and can withstand high voltages and large currents. And the IGBT has high thermal stability and impact resistance and can maintain stable performance in a harsh working environment. The on-resistance of the IGBT is relatively low, and the loss during the switching process is small, so it has high efficiency.

[0115] The relay realizes the on-off of the circuit through mechanical contacts and has the function of electrical isolation. In addition, the relay can withstand a large load current and voltage and is applicable to various load types. The control signal of the relay is relatively simple, and a high-voltage and large-current load can be controlled by a low-voltage and low-current signal.

[0116] Specifically, which high-frequency switch is selected for the first switch 41, the second switch 42, the third switch 43, the fourth switch 51, the fifth switch 52, and the sixth switch 53 can be selected according to actual usage requirements.

[0117] Please refer toFigure 4 and Figure 5 In some embodiments, the bidirectional DCDC converter 100 further includes a voltage detection circuit 70, and the voltage detection circuit 70 is connected in parallel to the first end 10 and / or the second end 20.

[0118] In this way, the voltages of the first end 10 and the second end 20 can be detected at any time through the voltage detection circuit 70, avoiding excessive voltage.

[0119] Specifically, the voltage detection circuit 70 is an electronic circuit used to monitor and measure the voltage level in a circuit. This kind of circuit is widely used in various electronic devices, power management systems, protection circuits, and automatic control systems to ensure that the device operates within the correct voltage range and prevent damage or faults caused by overvoltage or undervoltage.

[0120] In the embodiment of the present application, the number of the voltage detection circuits 70 is two, and the two voltage detection circuits 70 are respectively connected in parallel to the first end 10 and the second end 20.

[0121] Please refer to Figure 4 , in some embodiments, the voltage detection circuit 70 includes an operational amplifier 71 and several resistors 72 connected in series. Two input terminals of the operational amplifier 71 are connected to both ends of any one resistor 72, and the output terminal of the operational amplifier 71 is connected to the controller 60.

[0122] In this way, the voltages of the first end 10 and the second end 20 are detected through the operational amplifier 71 and the controller 60, which is beneficial to respond more timely to problems such as excessive voltage.

[0123] Specifically, the operational amplifier 71 is a circuit unit named from a functional perspective, which has multiple functions such as amplification, summation, and integration, and can jointly form a certain functional module in combination with a feedback network.

[0124] In the embodiment of the present application, it includes a first resistor, a second resistor, and a third resistor connected in series. The operational amplifier 71 is connected in parallel to both ends of the first resistor and is connected to the controller 60.

[0125] In other embodiments, the operational amplifier 71 can also be connected in parallel to both ends of other resistors 72.

[0126] Please refer to Figure 5 , in some embodiments, the voltage detection circuit 70 includes an isolator 73, an operational amplifier 71, and several resistors 72 connected in series. The isolator 73 is connected in parallel to any one resistor 72, the output terminal of the isolator 73 is connected to the operational amplifier 71, and the output terminal of the operational amplifier 71 is connected to the controller 60.

[0127] In this way, the isolator 73 can reduce the errors caused by signal interference and leakage, and improve the accuracy and reliability of sampling.

[0128] Specifically, the isolator 73 is a device that uses the principle of linear optocoupler isolation or other physical effects (such as electromagnetic induction, optoelectronic conversion, etc.) to convert the input signal and output it, while achieving isolation between the input, output, and working power supply.

[0129] In the embodiment of the present application, it includes a first resistor, a second resistor, and a third resistor connected in series. The isolator 73 is connected in parallel across the first resistor and is connected to the operational amplifier 71, and the operational amplifier 71 is further connected to the controller 60.

[0130] In other embodiments, the operational amplifier 71 can also be connected in parallel across other resistors 72.

[0131] Please refer to Figure 2 and Figure 3 , in certain embodiments, the controller 60 is configured to control the first switch 41 and the third switch 43 to be turned off and the second switch 42 to be turned on when the voltage at the first end 10 is greater than a predetermined voltage.

[0132] In this way, when the voltage at the first end 10 is high, the first primary DCDC circuit 34 and the second primary DCDC circuit 34 at the first end 10 form a voltage-dividing circuit to avoid damage to electrical components caused by excessive voltage.

[0133] Specifically, in the embodiment of the present application, the predetermined voltage is 500V.

[0134] When it is detected that the voltage at the first end 10 is greater than 500V, the controller 60 controls the second switch 42 to be turned on and controls the first switch 41 and the third switch 43 to be turned off, so that the first primary DCDC circuit 341 and the second primary DCDC circuit 342 are connected in series to form a voltage-dividing circuit. The voltage of the first primary DCDC circuit 341 plus the voltage of the second primary DCDC circuit 342 is equal to the input voltage. The voltage of the first primary DCDC circuit 341 is reduced by half relative to the input voltage, and the voltage of the second primary DCDC circuit 342 is also reduced by half relative to the input voltage, thereby avoiding damage to electrical components caused by excessive voltage.

[0135] Furthermore, after series voltage division, the withstand voltage ratings of the switching tubes in the first primary full-bridge circuit 3411 and the second primary full-bridge circuit 3421 in the primary DCDC circuit 34 can be relatively halved, and the withstand voltage ratings of the first primary capacitor 3412 and the second primary capacitor 3422 can also be relatively halved. In this way, the bidirectional DC power converter 100 can select power devices with relatively lower withstand voltage ratings, greatly reducing the cost of the bidirectional DC power converter 100.

[0136] In some embodiments, the controller 60 is configured to control the second switch 42 to turn off and the first switch 41 and the third switch 43 to turn on when the voltage at the first end 10 is less than or equal to a predetermined voltage.

[0137] In this way, when the voltage at the first end 10 is low, the current at the first end 10 is large at this time. The first primary DCDC circuit 34 and the second primary DCDC circuit 34 at the first end 10 form a shunt circuit to avoid damage to electrical components caused by excessive current.

[0138] Specifically, in the embodiments of the present application, the predetermined voltage is 500V.

[0139] When it is detected that the first end 10 is less than or equal to 500V, the controller 60 controls the first switch 41 and the third switch 43 to turn on, and controls the second switch 42 to turn off, so that the first primary DCDC circuit 341 and the second primary DCDC circuit 342 operate in parallel to form a shunt circuit. The current of the first primary DCDC circuit 341 is reduced by half relative to the input current, and the current of the second primary DCDC circuit 342 is also reduced by half relative to the input current, thus avoiding damage to electrical components caused by excessive current. And since the input current is equal to the sum of the current of the first primary DCDC circuit 341 and the current of the second primary DCDC circuit 342, the total input current of the first primary DCDC circuit 341 and the second primary DCDC circuit 342 increases by a factor of two, and the input power also increases by a factor of two.

[0140] In some embodiments, the controller 60 is configured to control the fourth switch 51 and the sixth switch 53 to turn off and the fifth switch 52 to turn on when the voltage at the second end 20 is greater than the predetermined voltage.

[0141] In this way, when the voltage at the second end 20 is high, the first secondary DCDC circuit 351 and the second secondary DCDC circuit 352 at the second end 20 both form voltage-dividing circuits to avoid damage to electrical components caused by excessive voltage.

[0142] Specifically, in the embodiments of the present application, the predetermined voltage is 500V.

[0143] When it is detected that the second end 20 is greater than 500V, the controller 60 controls the fifth switch 52 to turn on, and controls the fourth switch 51 and the sixth switch 53 to turn off, so that the first secondary DCDC circuit 351 and the second secondary DCDC circuit 352 operate in series to form a voltage-dividing circuit. The voltage of the first secondary DCDC circuit 351 plus the voltage of the second secondary DCDC circuit 352 is equal to the output voltage. The voltage of the first secondary DCDC circuit 351 is reduced by half relative to the output voltage, and the voltage of the second secondary DCDC circuit 352 is also reduced by half relative to the output voltage, thus avoiding damage to electrical components caused by excessive voltage.

[0144] Further, after series voltage division, the breakdown voltage ratings of the switching tubes in the first secondary full-bridge circuit 3511 and the second secondary full-bridge circuit 3521 in the secondary DCDC circuit 35 can be relatively halved, and the breakdown voltage ratings of the first secondary capacitor 3512 and the second secondary capacitor 3522 can also be relatively halved. In this way, the bidirectional DC power converter 100 can select power devices with relatively low breakdown voltage ratings, greatly reducing the cost of the bidirectional DC power converter 100.

[0145] In some embodiments, the controller 60 is configured to control the fifth switch 52 to turn off and the fourth switch 51 and the sixth switch 53 to turn on when the voltages at the second end 20 are both less than or equal to a predetermined voltage.

[0146] In this way, when the output voltages are all low voltages, the output current is large at this time, and the first secondary DCDC circuit 351 and the second secondary DCDC circuit 352 at the second end 20 form a shunt circuit to avoid damage to electrical components caused by excessive current.

[0147] Specifically, in the embodiments of the present application, the predetermined voltage is 500V.

[0148] When it is detected that the second end 20 is less than or equal to 500V, the controller 60 controls the fourth switch 51 and the sixth switch 53 to turn on, and controls the fifth switch 52 to turn off, so that the first secondary DCDC circuit 351 and the second secondary DCDC circuit 352 operate in parallel to form a shunt circuit. The voltage of the first secondary DCDC circuit 351 is reduced by half relative to the output current, and the voltage of the second secondary DCDC circuit 352 is also reduced by half relative to the output current, thereby avoiding damage to electrical components caused by excessive current. And since the output current is equal to the sum of the current of the first secondary DCDC circuit 351 and the current of the second secondary DCDC circuit 352, the total output current of the first secondary DCDC circuit 351 and the second secondary DCDC circuit 352 increases by a factor of two, and the output power also increases by a factor of two.

[0149] Please refer to Figure 2 and Figure 3 , in some embodiments, the primary resonant network 36 includes a first capacitor 364 and a first inductor 363 connected in series between the primary DCDC circuit 34 and the primary side of the transformer 33 in sequence;

[0150] The secondary resonant network 37 includes a second inductor 373 and a second capacitor 374 connected in series between the secondary DCDC circuit 35 and the secondary side of the transformer 33 in sequence.

[0151] In this way, the primary resonant network 36 and the secondary resonant network 37 can utilize the energy storage characteristics of the inductor and the capacitor to achieve resonance through the alternating conversion of electromagnetic energy.

[0152] Specifically, the first primary resonant network 361 and the second primary resonant network 362 both include a first inductor 363 and a first capacitor 364 connected in series; the first secondary resonant network 371 and the second secondary resonant network 372 both include a second inductor 373 and a second capacitor 374 connected in series. Among them, the first inductor 363 and the second inductor 373 store energy by generating a magnetic field and release this energy when needed. This energy storage characteristic enables the first inductor 363 and the second inductor 373 to smoothly regulate the changes in current and voltage during the resonance process. The first capacitor 364 and the second capacitor 374 control the changes in current and voltage in the circuit by storing and releasing charges. When the voltage in the circuit changes, the capacitor absorbs or releases charges to maintain the stability of the voltage.

[0153] Furthermore, the first inductor 363 and the first capacitor 364 of the primary resonant network 36 can be connected in series on the same side of the primary side of the transformer 33, and the connection order of the first inductor 363 and the first capacitor 364 is not overly restricted. Similarly, the second inductor 373 and the second capacitor 374 of the secondary resonant network 37 can be connected in series on the same side of the secondary side of the transformer 33, and the connection order of the second inductor 373 and the second capacitor 374 is also not overly restricted.

[0154] In some embodiments, the first inductor 363 and the first capacitor 364 of the primary resonant network 36 can also be connected in series on both sides of the primary side of the transformer 33. Similarly, the second inductor 373 and the second capacitor 374 of the secondary resonant network 37 can also be connected in series on both sides of the secondary side of the transformer 33.

[0155] In some embodiments, the present application also provides an energy storage system, which includes: at least one battery pack and an inverter, where at least one battery pack is used to store or output electric energy, and the inverter integrates the bidirectional DCDC converter described in any one of the above. In some embodiments, the inverter further includes a DC / AC bidirectional conversion circuit for converting direct current into alternating current, such as converting the direct current in the battery pack into alternating current and outputting it externally, and / or for converting alternating current into direct current, such as converting mains power into direct current and storing it in the at least one battery pack.

[0156] In some embodiments, the bidirectional DC power conversion circuit is configured such that when the energy storage power system charges an electric vehicle, the power flow direction of the bidirectional DC power conversion circuit is from the first end 10 to the second end 20, and when the electric vehicle charges the energy storage power system, the power flow direction of the bidirectional DC power conversion circuit is from the second end 20 to the first end 10.

[0157] Thus, the first end 10 can be connected to the input end of the DC charging pile 1000, and the second end 20 can be connected to the output end of the DC charging pile 1000.

[0158] Specifically, in the embodiment of the present application, the first end 10 serves as the input end, and the second end 20 serves as the output end. The power flow direction of the bidirectional DC power conversion circuit 100 is from the first end 10 to the second end 20. In other embodiments, the second end 20 can also be used as the input end, and the first end 10 can be used as the output end. At this time, the power flow direction of the bidirectional DC power conversion circuit 100 is from the second end 20 to the first end 10.

[0159] In some embodiments, the energy storage power supply system is a household energy storage power supply system or a balcony photovoltaic energy storage system. Among them, the household energy storage power supply system is usually relatively large, and its installed position is relatively fixed and immovable, with a relatively large capacitance and a relatively large provided power; while the balcony photovoltaic energy storage power supply system is relatively miniaturized and easy to carry and move, and can be transferred according to the user's electricity consumption needs, such as from the balcony position to the garage or even outdoors, etc., with a relatively small capacitance and a relatively small provided power.

[0160] In the description of this specification, the description with reference to the terms "certain embodiments", "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0161] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" can explicitly or implicitly include at least one of the said features. In the description of the present application, the meaning of "a plurality" is at least two, such as two, three, unless otherwise specifically and clearly defined.

[0162] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A bidirectional DCDC converter, characterized in that: include: First end; The second end; At least two bidirectional DCDC units, each of the bidirectional DCDC units comprising a transformer, a primary DCDC circuit and a primary resonant network sequentially connected between the first end and the primary side of the transformer, and a secondary DCDC circuit and a secondary resonant network sequentially connected between the second end and the secondary side of the transformer; a first switch circuit connected between the first end and the primary DCDC circuit; a second switch circuit connected between the second end and the secondary side DCDC circuit; The controller is configured to control the on-off of the switch in the first switching circuit so that the primary DCDC circuits of the at least two bidirectional DCDC units are connected in series or in parallel, and / or to control the on-off of the switch in the second switching circuit so that the secondary DCDC circuits of the at least two bidirectional DCDC units are connected in series or in parallel.

2. The bidirectional DCDC converter according to claim 1, characterized in that: The bidirectional DCDC converter comprises a first bidirectional DCDC unit and a second bidirectional DCDC unit, wherein the first bidirectional DCDC unit comprises a first transformer, a first primary DCDC circuit and a first primary resonant network sequentially connected between the first end and the primary side of the first transformer, and a first secondary DCDC circuit and a first secondary resonant network sequentially connected between the second end and the secondary side of the first transformer; The second bidirectional DCDC unit includes a second transformer, a second primary DCDC circuit and a second primary resonant network connected in sequence between the first end and the primary side of the second transformer, and a second secondary DCDC circuit and a second secondary resonant network connected in sequence between the second end and the secondary side of the second transformer.

3. The bidirectional DCDC converter according to claim 2, characterized in that: The first switch circuit includes a first switch connected between the positive electrode of the first end and the second primary DCDC circuit, a second switch connected between the first primary DCDC circuit and the second primary DCDC circuit, and a third switch connected between the negative electrode of the first end and the first primary DCDC circuit; The second switch circuit includes a fourth switch connected between the second positive terminal and the second secondary DCDC circuit, a fifth switch connected between the first secondary DCDC circuit and the second secondary DCDC circuit, and a sixth switch connected between the second negative terminal and the first secondary DCDC circuit.

4. The bidirectional DCDC converter according to claim 3, characterized in that: The first primary DCDC circuit comprises a first primary full-bridge circuit and a first primary capacitor connected in parallel, two ends of the first primary full-bridge circuit are connected to two ends of the first primary capacitor, the other two ends of the first primary full-bridge circuit are connected to two electrodes of the primary side of the first transformer, and the first primary capacitor is connected to the positive and negative electrodes of the first end; The second primary DCDC circuit comprises a second primary full-bridge circuit and a second primary capacitor connected in parallel, two ends of the second primary full-bridge circuit are connected to two ends of the second primary capacitor, the other two ends of the second primary full-bridge circuit are connected to two electrodes of the primary side of the second transformer, and the second primary capacitor is connected to the positive and negative electrodes of the first end; The first secondary DCDC circuit comprises a first secondary full-bridge circuit and a first secondary capacitor connected in parallel, two ends of the first secondary full-bridge circuit are connected to two ends of the first secondary capacitor, the other two ends of the first secondary full-bridge circuit are connected to two electrodes of the secondary side of the first transformer, and the first secondary capacitor is connected to the positive and negative electrodes of the second end; The second secondary DCDC circuit includes a second secondary full-bridge circuit and a second secondary capacitor connected in parallel, two ends of the second secondary full-bridge circuit are connected to two ends of the second secondary capacitor, the other two ends of the second secondary full-bridge circuit are connected to two electrodes of the secondary side of the second transformer, and the second secondary capacitor is connected to the positive and negative poles of the second end.

5. The bidirectional DCDC converter according to claim 4, characterized in that: One end of the first primary capacitor is connected to the positive electrode of the first end, and the other end is connected to the negative electrode of the first end through the third switch and to the second primary capacitor through the second switch; One end of the second primary capacitor is connected to the negative electrode of the first end, and the other end is connected to the positive electrode of the first end through the first switch and to the first primary capacitor through the second switch; One end of the first secondary capacitor is connected to the positive electrode of the second end, and the other end is connected to the negative electrode of the second end through the sixth switch and to the second secondary capacitor through the fifth switch; One end of the second secondary capacitor is connected to the negative electrode of the second end, and the other end is connected to the positive electrode of the second end through the fourth switch and to the first secondary capacitor through the fifth switch.

6. The bidirectional DCDC converter according to claim 3, characterized in that: The first switch, the second switch, the third switch, the fourth switch, the fifth switch and / or the sixth switch are high-frequency switching switches.

7. The bidirectional DCDC converter according to claim 6, characterized in that: The first switch, the second switch, the third switch, the fourth switch, the fifth switch and / or the sixth switch are any one of MOS tubes, IGBTs or relays.

8. The bidirectional DCDC converter according to claim 3, characterized in that: The bidirectional DCDC converter further includes a voltage detection circuit, and the voltage detection circuit is connected in parallel to the first end and / or the second end.

9. The bidirectional DCDC converter according to claim 8, characterized in that: The voltage detection circuit includes an operational amplifier and a plurality of resistors connected in series, wherein two input terminals of the operational amplifier are connected to two ends of any one of the resistors, and an output terminal of the operational amplifier is connected to the controller.

10. The bidirectional DCDC converter according to claim 8, characterized in that: The voltage detection circuit includes an isolator, an operational amplifier and a plurality of resistors connected in series, the isolator is connected in parallel with any one of the resistors, the output end of the isolator is connected to the operational amplifier, and the output end of the operational amplifier is connected to the controller.

11. The bidirectional DCDC converter according to claim 3, characterized in that: The controller is configured to control the first switch and the third switch to be turned off and the second switch to be turned on when the voltage at the first terminal is greater than a predetermined voltage.

12. The bidirectional DCDC converter according to claim 3, characterized in that: The controller is configured to control the second switch to be turned off and the first switch and the third switch to be turned on when the voltage at the first end is less than or equal to a predetermined voltage.

13. The bidirectional DCDC converter according to claim 3, characterized in that: The controller is configured to control the fourth switch and the sixth switch to be turned off and the fifth switch to be turned on when the voltage at the second end is greater than a predetermined voltage.

14. The bidirectional DCDC converter according to claim 3, characterized in that: The controller is configured to control the fifth switch to be turned off and the fourth switch and the sixth switch to be turned on when the voltage at the second end is less than or equal to a predetermined voltage.

15. The bidirectional DCDC converter according to claim 1, characterized in that: The primary resonant network comprises a first capacitor and a first inductor connected in series between the primary DCDC circuit and the primary side of the transformer; The secondary resonant network includes a second inductor and a second capacitor which are sequentially connected in series between the secondary DCDC circuit and the secondary side of the transformer.

16. A DC charging gun, characterized in that: include: A charging gun, which is used to connect to an electric vehicle; The bidirectional DCDC converter according to any one of claims 1 to 15, wherein the first end is connected to the energy storage power supply system, and the second end is connected to the charging gun.

17. The DC charging gun according to claim 16, characterized in that: The bidirectional DCDC converter is configured so that when the energy storage power supply system charges the electric vehicle, the power of the bidirectional DCDC converter flows from the first end to the second end; and when the electric vehicle charges the energy storage power supply system, the power of the bidirectional DCDC converter flows from the second end to the first end.

18. An energy storage system, characterized in that: include: at least one battery pack, the at least one battery pack being used to store electrical energy or output electrical energy; An inverter, wherein the inverter integrates the bidirectional DCDC converter as described in claims 1-15.

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