Wide-voltage bidirectional charging and discharging device and control method thereof

Abstract

The invention discloses a wide-voltage bidirectional charging and discharging device and a control method thereof, the wide-voltage bidirectional charging and discharging device comprises a first bidirectional inversion module, a first transformer, a second bidirectional inversion module, a first voltage conversion module and a control module, the first voltage conversion module is controlled to be switched to a boost conversion state or a buck conversion state according to the charging and discharging state, the voltage of the first direct current port, the voltage of the fourth direct current port and the turn ratio of the first transformer; according to the technical scheme, the voltage is monitored in real time, the step-up state or the step-down state is intelligently switched according to the turn ratio of the first transformer, bidirectional charging and discharging control in a wide voltage range is achieved, the problems that an existing device is single in function and limited in adaptation range are solved, and the service life of the device is prolonged. And moreover, the compatibility of batteries and loads with different voltage levels is greatly improved, the efficient and flexible charging and discharging requirements in multiple scenes are met, and good applicability and popularization value are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage inverters, and particularly to a wide-voltage bidirectional charging and discharging device and its control method. Background Art

[0002] With the rapid development of renewable energy technologies, green energies such as solar energy and wind energy have been widely applied in various energy systems. At the same time, the popularization of scenarios such as electric vehicles, outdoor energy storage, and power emergencies has also driven a strong demand for efficient and flexible charging and discharging equipment. However, existing charging and discharging equipment generally has problems such as single function and limited application scenarios. For example, most traditional devices only support single-direction charging or discharging and are difficult to be compatible with battery systems of multiple voltage levels. In addition, when faced with high-voltage battery systems for cold chain transportation (such as 300V to 500V) and low-voltage battery systems used in RVs, etc. (such as 24V, 48V), existing devices usually cannot achieve compatible charging across voltage systems. This problem is particularly prominent in distributed energy systems, outdoor portable energy storage devices, and emergency rescue fields.

[0003] In practical applications, common buck-boost topologies such as LLC resonant converters and phase-shifted full-bridge circuits have limited output voltage adjustment ranges. For example, the output voltage of an LLC converter can generally only be adjusted between 0.5 and 1.2 times the rated value, and the output adjustment range of a phase-shifted full-bridge is also only about 0.2 to 1 times. These limitations make it difficult for the equipment to meet the bidirectional charging and discharging requirements of wide voltage range input and output. Summary of the Invention

[0004] Embodiments of the present invention provide a wide-voltage bidirectional charging and discharging device and its control method to solve the above technical problems.

[0005] In a first aspect of an embodiment of the present invention, a wide-voltage bidirectional charging and discharging device is provided, including: A first bidirectional inverter module, which includes a first DC port and a first AC port and is used for bidirectional conversion between DC voltage and AC voltage; A first transformer, which includes a first primary coil and a first secondary coil, and the first primary coil is connected to the first AC port of the first bidirectional inverter module; A second bidirectional inverter module, which includes a second AC port and a second DC port, and the second AC port is connected to the first secondary coil to perform bidirectional conversion between AC voltage and DC voltage; A first voltage conversion module, which includes a third DC port and a fourth DC port, and the third DC port is connected to the second DC port and is used for switching between a boost conversion state and a buck conversion state between the third DC port and the fourth DC port; A control module, which is respectively connected to the first bidirectional inverter module, the second bidirectional inverter module, and the first voltage conversion module, and is used to control the first voltage conversion module to switch to a boost conversion state or a buck conversion state according to the charge and discharge state, the voltage of the first DC port, the voltage of the fourth DC port, and the turns ratio of the first transformer.

[0006] Optionally, when in the charging state, a first voltage is input to the fourth DC port, and a second voltage is output from the first DC port. The control module is used to control the first voltage conversion module to switch to the buck conversion state when the ratio between the second voltage and the first voltage is greater than the turns ratio of the first secondary coil and the first primary coil of the first transformer; The control module is further used to control the first voltage conversion module to switch to the boost conversion state when the ratio between the second voltage and the first voltage is less than the turns ratio of the first secondary coil and the first primary coil of the first transformer.

[0007] Optionally, when in the discharging state, a third voltage is input to the first DC port, and a fourth voltage is output from the fourth DC port. The control module is used to control the first voltage conversion module to switch to the boost conversion state when the ratio between the fourth voltage and the third voltage is greater than the turns ratio of the first secondary coil and the first primary coil of the first transformer; The control module is further used to control the first voltage conversion module to switch to the buck conversion state when the ratio between the fourth voltage and the third voltage is less than the turns ratio of the first secondary coil and the first primary coil of the first transformer.

[0008] Optionally, the first voltage conversion module includes a first switching switch, a first inductor, a first switching tube, a second switching tube, and a second switching switch. The first common end of the first switching switch is the first end of the third DC port. The first switching end of the first switching switch is respectively connected to the first end of the first inductor and the fourth switching end of the second switching switch. The second switching end of the first switching switch is respectively connected to the second end of the first switching tube and the third switching end of the second switching switch. The second end of the first inductor is respectively connected to the first end of the first switching tube and the first end of the second switching tube. The second end of the second switching tube is the second end of the third DC port and the second end of the fourth DC port. The second common end of the second switching switch is the first end of the fourth DC port.

[0009] Optionally, the control module controls the first common terminal of the first switching switch to be connected to the first switching terminal of the first switching switch, and controls the second common terminal of the second switching switch to be connected to the third switching terminal of the second switching switch, so as to control the first voltage conversion module to switch to the buck conversion state.

[0010] Optionally, the control module controls the first common terminal of the first switching switch to be connected to the second switching terminal of the first switching switch, and controls the second common terminal of the second switching switch to be connected to the fourth switching terminal of the second switching switch, so as to control the first voltage conversion module to switch to the boost conversion state.

[0011] Optionally, the wide-voltage bidirectional charge and discharge device further includes: A third bidirectional inverter module, which includes a fifth DC port and a fifth AC port, and is used for bidirectional conversion between DC voltage and AC voltage; A second transformer, which includes a second primary coil and a second secondary coil, and the second primary coil is connected to the fifth AC port of the third bidirectional inverter module; A fourth bidirectional inverter module, which includes a sixth AC port and a sixth DC port, and the sixth AC port is connected to the second secondary coil to perform bidirectional conversion between AC voltage and DC voltage; A second voltage conversion module, which includes a seventh DC port and an eighth DC port, the seventh DC port is connected to the sixth DC port, and the eighth DC port is connected to the fourth DC port, and is used for switching between a boost conversion state and a buck conversion state between the seventh DC port and the eighth DC port.

[0012] Optionally, the second voltage conversion module includes a third switching switch, a second inductor, a third switching tube, a fourth switching tube, and a fourth switching switch. The third common terminal of the third switching switch is the first end of the fifth DC port. The fifth switching terminal of the third switching switch is respectively connected to the first end of the second inductor and the eighth switching terminal of the fourth switching switch. The sixth switching terminal of the third switching switch is respectively connected to the second end of the third switching tube and the seventh switching terminal of the fourth switching switch. The second end of the second inductor is respectively connected to the first end of the third switching tube and the first end of the fourth switching tube. The second end of the fourth switching tube is the second end of the third DC port and the second end of the fourth DC port. The fourth common terminal of the fourth switching switch is the first end of the fourth DC port.

[0013] The second aspect of the embodiments of the present invention provides a control method based on the wide-voltage bidirectional charge and discharge device described in the first aspect. The control method includes: Control the first voltage conversion module to switch to a boost conversion state or a buck conversion state according to the charge and discharge state, the voltage of the first DC port, the voltage of the fourth DC port, and the turns ratio of the first transformer.

[0014] Optionally, when in the charging state, a first voltage is input to the fourth DC port, and a second voltage is output from the first DC port. Controlling the first voltage conversion module to switch to a boost conversion state or a buck conversion state according to the charge and discharge state, the voltage of the first DC port, the voltage of the fourth DC port, and the turns ratio of the first transformer includes: When the ratio between the second voltage and the first voltage is greater than the turns ratio of the first secondary coil and the first primary coil of the first transformer, control the first voltage conversion module to switch to the buck conversion state; when the ratio between the second voltage and the first voltage is less than the turns ratio of the first secondary coil and the first primary coil of the first transformer, control the first voltage conversion module to switch to the boost conversion state.

[0015] The technical effect of the embodiment of the present invention is as follows: By setting the first bidirectional inverter module, the first transformer, the second bidirectional inverter module, and the first voltage conversion module, and cooperating with the control module to monitor the voltage in real time and intelligently switch the boost or buck state according to the turns ratio of the first transformer, bidirectional charge and discharge control within a wide voltage range is achieved. This technical solution not only solves the problems of single function and limited adaptation range of existing equipment, but also greatly improves the compatibility with batteries and loads of different voltage levels, meets the efficient and flexible charge and discharge requirements in multiple scenarios, and has good applicability and promotion value. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings without creative efforts.

[0017] Figure 1 It is the first structural schematic diagram of a wide-voltage bidirectional charge and discharge device provided by Embodiment 1 of the present invention; Figure 2 It is the structural schematic diagram of the first voltage conversion module of a wide-voltage bidirectional charge and discharge device provided by Embodiment 1 of the present invention; Figure 3 It is the first circuit diagram of a wide-voltage bidirectional charge and discharge device provided by Embodiment 1 of the present invention; Figure 4It is the first connection relationship diagram in the first circuit diagram of a wide-voltage bidirectional charge and discharge device provided in the first embodiment of the present invention; Figure 5 It is the equivalent circuit diagram of the first connection relationship in the first circuit diagram of a wide-voltage bidirectional charge and discharge device provided in the first embodiment of the present invention; Figure 6 It is the second connection relationship diagram in the first circuit diagram of a wide-voltage bidirectional charge and discharge device provided in the first embodiment of the present invention; Figure 7 It is the equivalent circuit diagram of the second connection relationship in the first circuit diagram of a wide-voltage bidirectional charge and discharge device provided in the first embodiment of the present invention; Figure 8 It is the second structural schematic diagram of a wide-voltage bidirectional charge and discharge device provided in the first embodiment of the present invention; Figure 9 It is the structural schematic diagram of the second voltage conversion module of a wide-voltage bidirectional charge and discharge device provided in the first embodiment of the present invention; Figure 10 It is the second circuit diagram of a wide-voltage bidirectional charge and discharge device provided in the first embodiment of the present invention; In the figure: 101, the first bidirectional inverter module; 102, the first transformer; 103, the second bidirectional inverter module; 104, the first voltage conversion module; 105, the control module; 111, the first switch; 112, the first inductor; 113, the first switch tube; 114, the second switch; 115, the second switch tube; 201, the third bidirectional inverter module; 202, the second transformer; 203, the fourth bidirectional inverter module; 204, the second voltage conversion module; 211, the third switch; 212, the second inductor; 213, the third switch tube; 214, the fourth switch; 215, the fourth switch tube. Detailed implementation manners

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0019] It should be understood that the present invention can be implemented in different forms and should not be construed as limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated. The same reference numerals denote the same elements throughout.

[0020] It should be understood that when an element or layer is referred to as being "on", "adjacent to", "connected to", or "coupled to" another element or layer, it can be directly on, adjacent to, connected, or coupled to the other element or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on", "directly adjacent to", "directly connected to", or "directly coupled to" another element or layer, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Thus, without departing from the teachings of the present invention, the first element, component, region, layer, or part discussed below may be denoted as the second element, component, region, layer, or part.

[0021] The purpose of the terms used herein is only to describe specific embodiments and is not a limitation of the present invention. As used herein, the singular forms "a", "an", and "the" are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. As used herein, the term "and / or" includes any and all combinations of the associated listed items.

[0022] To fully understand the present invention, detailed structures and steps will be presented in the following description to illustrate the technical solutions proposed by the present invention. The preferred embodiments of the present invention are described in detail below. However, in addition to these detailed descriptions, the present invention may have other embodiments.

[0023] Embodiment 1 Embodiment 1 provides a wide-voltage bidirectional charge and discharge device, as Figure 1 shown, comprising: A first bidirectional inverter module 101, which includes a first DC port A1 and a first AC port B1, for bidirectionally converting DC voltage and AC voltage; A first transformer 102, which includes a first primary coil and a first secondary coil, and the first primary coil is connected to the first AC port B1 of the first bidirectional inverter module 101; A second bidirectional inverter module 103, which includes a second AC port B2 and a second DC port A2, and the second AC port B2 is connected to the first secondary coil to bidirectionally convert AC voltage and DC voltage; The first voltage conversion module 104, which includes a third DC port A3 and a fourth DC port A4. The third DC port A3 is connected to the second DC port A2 and is used to switch between a boost conversion state and a buck conversion state between the third DC port A3 and the fourth DC port A4; The control module 105, which is respectively connected to the first bidirectional inverter module 101, the second bidirectional inverter module 103, and the first voltage conversion module 104, is used to control the first voltage conversion module 104 to switch to a boost conversion state or a buck conversion state according to the charge and discharge state, the voltage of the first DC port A1, the voltage of the fourth DC port A4, and the turns ratio of the first transformer 102.

[0024] Among them, the first bidirectional inverter module 101 includes a first DC port A1 and a first AC port B1 and is used to convert DC voltage into AC voltage or rectify AC voltage into DC voltage, supporting bidirectional energy conversion operations for charging and discharging. The first DC port A1 is connected to a first external device. The first transformer 102 includes a first primary coil and a first secondary coil. The first primary coil is connected to the AC port of the first bidirectional inverter module 101. The first transformer 102 is used to step up or step down the alternating current and achieve electrical isolation between the input and output. Its turns ratio (N1:N2) provides a reference basis for subsequent voltage switching control. The second bidirectional inverter module 103 includes a second AC port B2 and a second DC port A2. The second AC port B2 is connected to the first secondary coil of the first transformer 102. The second bidirectional inverter module 103 is used to achieve bidirectional energy conversion between the AC output of the first transformer 102 and the DC on the battery side. The first voltage conversion module 104 includes a third DC port A3 and a fourth DC port A4. The third DC port A3 is connected to the second DC port A2 of the second bidirectional inverter module 103. The fourth DC port A4 is connected to a second external device. The first voltage conversion module 104 can switch between a boost mode (BOOST) and a buck mode (BUCK) to achieve energy matching between external devices of different voltage levels. The control module 105 is respectively connected to the first bidirectional inverter module 101, the second bidirectional inverter module 103, and the first voltage conversion module 104. Its main functions are: monitoring the voltages of the first DC port A1 and the fourth DC port A4; judging whether the current system is in a charging or discharging state; and controlling the first voltage conversion module 104 to enter the corresponding mode according to the voltage ratio and the turns ratio of the first transformer 102 to meet the requirements of the energy flow direction and voltage level matching.

[0025] The working process of this embodiment is as follows: 1. In the discharging mode: When the power supply output by the first external device is input through the first DC port A1, the first bidirectional inverter module 101 converts the direct current into alternating current; the alternating current is output to the secondary side after being stepped up or down by the first transformer 102; the second bidirectional inverter module 103 converts the alternating current into direct current; the control module 105 judges the relationship between the voltage ratio of the fourth DC port A4 and the first DC port A1 and the turns ratio N2 / N1 of the secondary coil and the primary coil of the first transformer 102, and automatically controls the first voltage conversion module 104 to enter the boost (BOOST) or buck (BUCK) mode; finally, the DC voltage is matched to the fourth DC port A4 through the first voltage conversion module 104 to charge the second external device.

[0026] 2. In the charging mode: When the power supply output by the second external device is input through the fourth DC port A4, the control module 105 judges the relationship between the voltage ratio of the fourth DC port A4 and the first DC port A1 and the turns ratio N2 / N1 of the first transformer 102, and automatically controls the first voltage conversion module 104 to enter the boost (BOOST) or buck (BUCK) mode; the second bidirectional inverter module 103 converts the direct current into alternating current; the alternating current passes through the first transformer 102 and is transformed by the first bidirectional inverter module 101 and then output to the first external device to realize the charging function.

[0027] 3. Mode switching control: The control module 105 monitors the system state and voltage data in real time; automatically judges the current charging or discharging state, and switches the step-up / step-down state according to the voltage ratio relationship to ensure the automation and efficiency of the system operation.

[0028] The technical effect of the technical solution provided in the first embodiment is as follows: By setting the first bidirectional inverter module 101, the first transformer 102, the second bidirectional inverter module 103 and the first voltage conversion module 104, and cooperating with the control module 105 to monitor the voltage in real time and intelligently switch the boost or buck state according to the turns ratio of the first transformer 102, the bidirectional charge and discharge control within a wide voltage range is realized. This technical solution not only solves the problems of single function and limited adaptation range of existing devices, but also greatly improves the compatibility with batteries and loads of different voltage levels, meets the efficient and flexible charge and discharge requirements in multiple scenarios, and has good applicability and promotion value.

[0029] As an implementation manner, when in the charging state, the fourth DC port A4 inputs a first voltage, and the first DC port A1 outputs a second voltage. The control module 105 is configured to control the first voltage conversion module 104 to switch to the buck conversion state when the ratio between the second voltage and the first voltage is greater than the turn ratio of the first secondary coil and the first primary coil of the first transformer 102; the control module 105 is further configured to control the first voltage conversion module 104 to switch to the boost conversion state when the ratio between the second voltage and the first voltage is less than the turn ratio of the first secondary coil and the first primary coil of the first transformer 102.

[0030] Wherein, when the wide-voltage bidirectional charging and discharging device is in the charging state, the fourth DC port A4 is connected to an external power source, such as a photovoltaic panel or a high-voltage DC bus, to input a first voltage V1, and the first DC port A1 is connected to a battery to output a second voltage V2, that is, to charge the battery; the control module 105 monitors the voltage values of the first voltage V1 and the second voltage V2 in real time, and makes a comparison and judgment based on the ratio between these two voltages and the turn ratio (N2 / N1, that is, the first secondary coil to the first primary coil) of the first transformer 102. The specific control logic is as follows: 1. If the ratio V2 / V1 of the second voltage to the first voltage is greater than the turn ratio N2 / N1, it indicates that the input voltage is relatively high, and the input voltage needs to be reduced to a charging voltage suitable for the battery; the control module 105 controls the first voltage conversion module 104 to enter the buck conversion state; through buck adjustment, the battery can obtain a safe and effective charging voltage.

[0031] 2. If the ratio V2 / V1 of the second voltage to the first voltage is less than the turn ratio N2 / N1, it indicates that the voltage of the battery is relatively high, and the voltage needs to be increased to meet the charging requirements. The control module 105 controls the first voltage conversion module 104 to enter the boost conversion state; the converted voltage is increased to a level suitable for charging the battery.

[0032] The technical effect of this implementation manner is that: by the control module 105 monitoring the ratio between the input voltage and the output voltage in real time and making a judgment in combination with the turn ratio of the first transformer 102, the intelligent switching between the boost mode and the buck mode is realized, and the charging path can be automatically adjusted according to different battery voltages and input voltage conditions. This solution not only improves the charging efficiency and system compatibility, but also reduces manual intervention, realizes the automation and high adaptability of the charging and discharging process, and is particularly suitable for bidirectional charging and discharging applications in multiple scenarios and multiple voltage levels.

[0033] As an implementation manner, when in the discharging state, the first DC port A1 inputs a third voltage, and the fourth DC port A4 outputs a fourth voltage. The control module 105 is configured to control the first voltage conversion module 104 to switch to the boost conversion state when the ratio between the fourth voltage and the third voltage is greater than the turn ratio of the first secondary coil and the first primary coil of the first transformer 102; the control module 105 is further configured to control the first voltage conversion module 104 to switch to the buck conversion state when the ratio between the fourth voltage and the third voltage is less than the turn ratio of the first secondary coil and the first primary coil of the first transformer 102.

[0034] Wherein, when the wide-voltage bidirectional charge and discharge device is in the discharging state, the first DC port A1 is connected to the battery, and inputs a third voltage V3 from the battery; the fourth DC port A4 is connected to an external load and outputs a fourth voltage V4; at this time, the goal of the system is to convert the battery voltage into an output voltage that meets the load requirements. In order to stabilize the output voltage and meet the target voltage requirement, the control module 105 judges by comparing the ratio of the fourth voltage V4 to the third voltage V3 with the turn ratio (N2 / N1) of the first transformer 102, and controls the working state of the first voltage conversion module 104. The specific control logic is as follows: 1. If the ratio V4 / V3 of the fourth voltage to the third voltage is greater than N2 / N1, it indicates that the target output voltage is higher than the voltage adjusted by the first transformer 102 from the battery voltage; the control module 105 controls the first voltage conversion module 104 to switch to the boost (BOOST) conversion state; raises the battery voltage to the required output voltage to ensure the normal operation of the load.

[0035] 2. If the ratio V4 / V3 of the fourth voltage to the third voltage is less than N2 / N1, it indicates that the target output voltage is lower than the battery voltage after conversion; the control module 105 controls the first voltage conversion module 104 to switch to the buck (BUCK) conversion state; through buck regulation, the output voltage is stabilized below the target value to avoid overvoltage impact on the load.

[0036] The technical effect of this implementation manner is that: by introducing a dynamic ratio judgment mechanism, the automatic selection and switching of the boost or buck path during the discharging process are realized. This method can flexibly adjust the energy transmission path according to the real-time relationship between the battery voltage and the target output voltage, improve the discharging efficiency and voltage matching accuracy, enhance the system's ability to adapt to loads of different voltage levels, ensure the stability and safety of the discharging process, and has good applicability and scalability.

[0037] As an implementation manner, such as Figure 2As shown, the first voltage conversion module 104 includes a first switching switch 111, a first inductor 112, a first switching transistor 113, a second switching transistor 115, and a second switching switch 114. The first common terminal a0 of the first switching switch 111 is the first end of the third DC port A3. The first switching terminal a1 of the first switching switch 111 is respectively connected to the first end of the first inductor 112 and the fourth switching terminal b2 of the second switching switch 114. The second switching terminal a2 of the first switching switch 111 is respectively connected to the second end of the first switching transistor 113 and the third switching terminal b1 of the second switching switch 114. The second end of the first inductor 112 is respectively connected to the first end of the first switching transistor 113 and the first end of the second switching transistor 115. The second end of the second switching transistor 115 is the second end of the third DC port A3 and the second end of the fourth DC port A4. The second common terminal b0 of the second switching switch 114 is the first end of the fourth DC port A4. The control module 105 controls the first common terminal a0 of the first switching switch 111 to be connected to the first switching terminal a1 of the first switching switch 111, and controls the second common terminal b0 of the second switching switch 114 to be connected to the third switching terminal b1 of the second switching switch 114, so as to control the first voltage conversion module 104 to switch to the buck conversion state. The control module 105 controls the first common terminal a0 of the first switching switch 111 to be connected to the second switching terminal a2 of the first switching switch 111, and controls the second common terminal b0 of the second switching switch 114 to be connected to the fourth switching terminal b2 of the second switching switch 114, so as to control the first voltage conversion module 104 to switch to the boost conversion state.

[0038] Among them, the first switching switch 111 is a three-terminal switching device, having a first common terminal a0, a first switching terminal a1, and a second switching terminal a2; the first common terminal a0 is connected to the first end of the third DC port A3 for selecting the current flow direction; the control module 105 controls the first common terminal a0 of the first switching switch 111 to be connected to the first switching terminal a1 or the second switching terminal a2 according to whether it is in the boost or buck state currently. The second switching switch 114 is also a three-terminal structure, having a second common terminal b0, a third switching terminal b1, and a fourth switching terminal b2; the second common terminal b0 is connected to the first end of the fourth DC port A4; its two switching terminals are respectively connected to the paths extended by the first switching terminal a1 and the second switching terminal a2 of the first switching switch 111; the control module 105 controls its conduction path to form a complete current flow path. One end of the first inductor 112 is connected to the first switching terminal a1 of the first switching switch 111, and the other end is respectively connected to the first switching transistor 113 and the second switching transistor 115, for energy storage and energy conversion, and is the core component to realize the BUCK or BOOST mode. The first switching transistor 113 is used to cooperate with the first inductor 112 at a specific timing to realize current discontinuous control; one end of it is connected to the first inductor 112, and the other end is grounded (forming a path with the second switching switch 114). The second switching transistor 115 is connected in parallel with the first switching transistor 113 between the first inductor 112 and the grounding path; its second end is the second end of the third DC port A3 and the second end of the fourth DC port A4; it is used to control the current release path and synchronous rectification.

[0039] The working process of this embodiment is as follows: In the charging state: 1. Buck conversion state: The control module 105 controls the first common terminal a0 of the first switching switch 111 to be connected to the first switching terminal a1, and the second common terminal b0 of the second switching switch 114 to be connected to the third switching terminal b1; at this time, the current flows from the second switching switch 114 to the first switching transistor 113 to the first inductor 112 to the first switching switch 111; the first switching transistor 113 adjusts the current of the first inductor 112 during the high-frequency conduction and turn-off process, so as to realize the step-down voltage output.

[0040] 2. Boost conversion state: The control module 105 controls the first common terminal a0 of the first switching switch 111 to be connected to the second switching terminal a2, and the second common terminal b0 of the second switching switch 114 to be connected to the second switching terminal b2; the current flows from the second switching switch 114 to the first inductor 112 to the first switching transistor 113 to the first switching switch 111; after controlling the second switching transistor 115 to charge the first inductor 112, the first inductor 112 releases energy to the second switching transistor 115 to be output from the fourth DC port A4; realizing the boost operation with the output voltage greater than the input voltage.

[0041] In the discharge state: 1. Buck conversion state: The control module 105 controls the first common terminal a0 of the first switching switch 111 to be connected to the first switching terminal a1, and the second common terminal b0 of the second switching switch 114 to be connected to the third switching terminal b1; at this time, the current flows from the first end of the third DC port A3 through the first switching switch 111 to the first switching transistor 113 to the first inductor 112 to the output terminal (the fourth DC port A4); the first switching transistor 113 adjusts the current of the first inductor 112 during the high-frequency on and off processes, thereby realizing the step-down voltage output.

[0042] 2. Boost conversion state: The control module 105 controls the first common terminal a0 of the first switching switch 111 to be connected to the second switching terminal a2, and the second common terminal b0 of the second switching switch 114 to be connected to the second switching terminal b2; the current flows from the first end of the third DC port A3 into the second switching terminal of the first switching switch 111 to the first inductor 112 to the first switching transistor 113 / the second switching transistor 115; after controlling the second switching transistor 115 to charge the first inductor 112, the first inductor 112 releases energy to the second switching transistor 115 to the fourth DC port A4 for output; realizing the boost operation with the output voltage greater than the input voltage.

[0043] The technical effect of this embodiment lies in: By setting the first voltage conversion module 104 and combining the intelligent control of the control module 105 on the switching state, the free switching between the boost and buck modes under the same circuit structure is realized. This design not only improves the adaptability of the system to different voltage inputs and outputs, but also simplifies the hardware structure, improves the energy conversion efficiency and control response speed, has good versatility and practicability, and is particularly suitable for bidirectional charging and discharging applications in multiple scenarios.

[0044] The following is an illustration of this embodiment through a specific circuit structure: As Figure 3 shown, the first bidirectional inverter module 101 includes a first MOS transistor Q1, a second MOS transistor Q2, a third MOS transistor Q3, and a fourth MOS transistor Q4; the drain of the first MOS transistor Q1 and the drain of the second MOS transistor Q2 are commonly connected to the first end BAT+ of the first DC port A1 of the first bidirectional inverter module 101, the source of the third MOS transistor Q3 and the source of the fourth MOS transistor Q4 are commonly connected to the second end BAT- of the first DC port A1 of the first bidirectional inverter module 101, the source of the first MOS transistor Q1 and the drain of the third MOS transistor Q3 are commonly connected to the first end of the first AC port B1 of the first bidirectional inverter module 101, and the source of the second MOS transistor Q2 and the drain of the fourth MOS transistor Q4 are commonly connected to the second end of the first AC port B1 of the first bidirectional inverter module 101.

[0045] The second bidirectional inverter module 103 includes a first IGBT module Q5, a second IGBT module Q6, a third IGBT module Q7, and a fourth IGBT module Q8; the second end of the first IGBT module Q5 and the first end of the second IGBT module Q6 are commonly connected to the second end of the second AC port B2 of the second bidirectional inverter module 103, the second end of the third IGBT module Q7 and the first end of the fourth IGBT module Q8 are commonly connected to the first end of the second AC port B2 of the second bidirectional inverter module 103, the first end of the first IGBT module Q5 and the first end of the third IGBT module Q7 are commonly connected to the first end of the second DC port A2 of the second bidirectional inverter module 103, and the second end of the second IGBT module Q6 and the second end of the fourth IGBT module Q8 are commonly connected to the second end of the second DC port A2 of the second bidirectional inverter module 103.

[0046] In the first voltage conversion module 104, the first switching switch 111 is the switch S1, the first inductor 112 is the inductor L1, the first switching transistor 113 is the switching transistor Q9, the second switching transistor 115 is the switching transistor Q10, the second switching switch 114 is the switch S2, the common terminal a0 of the switch S1 is the first end of the third DC port A3, the first switching terminal a1 of the switch S1 is respectively connected to the first end of the inductor L1 and the fourth switching terminal b2 of the switch S2, the second switching terminal a2 of the switch S1 is respectively connected to the second end of the switching transistor Q9 and the third switching terminal b1 of the switch S2, the second end of the inductor L1 is respectively connected to the first end of the switching transistor Q9 and the first end of the switching transistor Q10, the second end of the switching transistor Q10 is the second end of the third DC port A3 and the second end of the fourth DC port A4, and the common terminal b0 of the switch S2 is the first end of the fourth DC port A4.

[0047] The working process of this circuit structure is as follows: When the system is in the charging state, that is, when the fourth DC port A4 (voltage is Vhv) supplies power to the first DC port A1 (voltage is Vbat), the control logic is as follows: 1. When Vhv / Vbat > N2 / N1, it means that the voltage of the fourth DC port A4 is higher and it is necessary to step down the voltage to charge the low-voltage battery; as Figure 4 shown, the control module 105 drives the common terminal a0 of the switch S1 to switch to the first switching terminal a1 of the switch S1, and drives the common terminal b0 of the switch S2 to switch to the third switching terminal b1 of the switch S2; starts the switching transistor Q9 to work, controls the switching transistor Q10 to turn off, and performs the BUCK step-down operation; adjusts the BUS voltage by controlling the conduction time of the switching transistor Q9; the system works in the open-loop control mode to provide a stable charging voltage to the battery side, and the equivalent circuit diagram is as Figure 5 .

[0048] 2. When Vhv / Vbat < N2 / N1, it indicates that the voltage of the fourth DC port is insufficient and needs to be boosted to match the battery charging voltage; as Figure 6 shown, the control module 105 drives the first common terminal a0 of the switch S1 to switch to the second switching terminal a2 of the switch S1, and drives the second common terminal b0 of the switch S2 to switch to the fourth switching terminal b2 of the switch S2; starts the switching transistor Q10 to work and performs BOOST boost operation; controls the switching transistor Q10 to adjust the BUS voltage to be suitable for battery charging; the system still operates in an open-loop manner to achieve efficient charging of the battery, and the equivalent circuit diagram is as Figure 7 .

[0049] When the system is in the discharging state, that is, when the first DC port A1 (voltage is Vbat) outputs electrical energy to the fourth DC port A4 (voltage is Vhv), the control logic is as follows: 1. When Vhv / Vbat > N2 / N1, it indicates that the target output voltage is higher than the current battery voltage; as Figure 4 shown, the control module 105 drives the first common terminal a0 of the switch S1 to switch to the second switching terminal a2 of the switch S1, and drives the second common terminal b0 of the switch S2 to switch to the fourth switching terminal b2 of the switch S2; starts the switching transistor Q10 to perform BOOST boost operation; adjusts the BUS voltage to meet the set target value at the output end; the system can set the output voltage through a display or a communication interface (such as CAN, RS485).

[0050] 2. When Vhv / Vbat < N2 / N1, it indicates that the target output voltage is lower than the battery voltage; as Figure 6 shown, the control module 105 drives the first common terminal a0 of the switch S1 to switch to the first switching terminal a1 of the switch S1, and drives the second common terminal b0 of the switch S2 to switch to the third switching terminal b1 of the switch S2; starts the switching transistor Q9 to perform BUCK buck operation; adjusts the BUS voltage to output a matching voltage to the high-voltage side.

[0051] As an implementation manner, as Figure 8 shown, the wide-voltage bidirectional charge and discharge device further includes: A third bidirectional inverter module 201, which includes a fifth DC port A5 and a fifth AC port B5, and is used for bidirectional conversion between DC voltage and AC voltage; A second transformer 202, which includes a second primary coil and a second secondary coil, and the second primary coil is connected to the fifth AC port B5 of the third bidirectional inverter module 201; A fourth bidirectional inverter module 203, which includes a sixth AC port B6 and a sixth DC port A6, and the sixth AC port B6 is connected to the second secondary coil to perform bidirectional conversion between AC voltage and DC voltage; The second voltage conversion module 204 includes a seventh DC port A7 and an eighth DC port A8. The seventh DC port A7 is connected to the sixth DC port A6, and the eighth DC port A8 is connected to the fourth DC port A4. It is used to switch between a boost conversion state and a buck conversion state between the seventh DC port A7 and the eighth DC port A8.

[0052] Among them, when the load power increases, the output voltage drops slightly, and the control module 105 will automatically distribute the current according to the voltage of each path; the path with a higher output voltage provides more current, and the path with a lower voltage provides less current to form automatic energy equalization; by presetting different voltage droop slopes (K values), proportional distribution is achieved. One of the modules acts as the host to adjust the bus voltage in real time; the other modules are slaves and output in a voltage following + current limiting manner; the main module controls the target voltage through the bus voltage, and the slave module only outputs a current consistent with its voltage; the energy distribution depends on the current limit or power limit set for each module. In the case of two-channel parallel connection: the output terminals (the fourth DC port A4 and the eighth DC port A8) of the first voltage conversion module 104 and the second voltage conversion module 204 are connected to the same Bus (bus); the control module 105 judges the current system voltage demand and the capabilities that each path can provide; through droop control or communication instructions, the power outputs of the two paths are automatically coordinated; for example, when the load power increases, if the first path has strong capabilities and its droop ratio is small, it will preferentially output more current; if the battery voltage of the second path is lower or its power capabilities are limited, its controller will automatically reduce the current output to achieve automatic current sharing.

[0053] The technical effect of this embodiment is that: by introducing a voltage droop control, master-slave control or communication coordination mechanism in the parallel structure, this technical solution can achieve dynamic and intelligent energy distribution between dual-channel or multi-channel energy paths, effectively improving the system stability and output capabilities, avoiding power conflicts or current reverse flow between paths, and is widely applicable to multi-module parallel power supply scenarios such as energy storage systems, DC microgrids, and vehicle-mounted power supply systems.

[0054] As an implementation, such as Figure 9As shown in the figure, the second voltage conversion module 204 includes a third switching switch 211, a second inductor 212, a third switching transistor 213, a fourth switching transistor 215, and a fourth switching switch 214. The third common terminal m0 of the third switching switch 211 is the first end of the fifth DC port A5. The fifth switching terminal m1 of the third switching switch 211 is respectively connected to the first end of the second inductor 212 and the eighth switching terminal n2 of the fourth switching switch 214. The sixth switching terminal m2 of the third switching switch 211 is respectively connected to the second end of the third switching transistor 213 and the seventh switching terminal n1 of the fourth switching switch 214. The second end of the second inductor 212 is respectively connected to the first end of the third switching transistor 213 and the first end of the fourth switching transistor 215. The second end of the fourth switching transistor 215 is the second end of the third DC port A3 and the second end of the fourth DC port A4. The fourth common terminal n0 of the fourth switching switch 214 is the first end of the fourth DC port A4.

[0055] Among them, the third switching switch 211 is used to select different energy paths in different operating modes to achieve the switching between boost and buck modes; the second inductor 212 is used as an energy storage element, which stores energy and then releases it in the boost mode, and smoothly transmits energy in the buck mode. It is the key magnetic device for realizing voltage conversion; the third switching transistor 213 is periodically turned on and off under the drive of the control module 105 to control the establishment and release of the inductor current; the control module 105 controls the fourth switching switch 214 to select an appropriate path according to the voltage judgment result to achieve the output switching in the boost or buck state. In the buck mode (BUCK): the control module 105 controls the third common terminal m0 of the third switching switch 211 to switch to the fifth switching terminal m1 of the third switching switch 211, and controls the fourth common terminal n0 of the fourth switching switch 214 to switch to the seventh switching terminal n1 of the fourth switching switch 214. The current enters from the third switching switch 211 and is regulated by the second inductor 212, the third switching transistor 213, and the fourth switching switch 214 for output. In the boost mode (BOOST): the control module 105 controls the third common terminal m0 of the third switching switch 211 to switch to the sixth switching terminal m2, and the fourth common terminal n0 of the fourth switching switch 214 to switch to the eighth switching terminal n2. The second inductor 212 stores energy periodically through control and releases it to the fourth DC port A4 to form a boost output.

[0056] The technical effect of this embodiment is that: by setting the second voltage conversion module 204, the automatic switching between boost and buck of the DC ports is realized, which not only ensures voltage compatibility, but also improves the voltage range and system efficiency of the circuit. This solution is applicable to various scenarios such as high and low voltage hybrid energy storage systems, DC microgrids, and electric vehicle energy management, and has good practicability and popularization value.

[0057] The following will illustrate this embodiment through a specific circuit structure: As Figure 10As shown in the figure, the third bidirectional inverter module 201 includes the eleventh MOS transistor Q11, the twelfth MOS transistor Q12, the thirteenth MOS transistor Q13, and the fourteenth MOS transistor Q14; the drains of the eleventh MOS transistor Q11 and the twelfth MOS transistor Q12 are commonly connected to the first end of the fifth DC port A5 of the third bidirectional inverter module 201, the sources of the thirteenth MOS transistor Q3 and the fourteenth MOS transistor Q14 are commonly connected to the second end of the fifth DC port A5 of the third bidirectional inverter module 201, the source of the eleventh MOS transistor Q11 and the drain of the thirteenth MOS transistor Q13 are commonly connected to the first end of the fifth AC port B5 of the third bidirectional inverter module 201, and the source of the twelfth MOS transistor Q12 and the drain of the fourteenth MOS transistor Q14 are commonly connected to the second end of the fifth AC port B5 of the third bidirectional inverter module 201.

[0058] The fourth bidirectional inverter module 203 includes the eleventh IGBT module Q15, the twelfth IGBT module Q16, the thirteenth IGBT module Q17, and the fourteenth IGBT module Q18; the second ends of the eleventh IGBT module Q15 and the twelfth IGBT module Q16 are commonly connected to the second end of the sixth AC port B6 of the fourth bidirectional inverter module 203, the second ends of the thirteenth IGBT module Q17 and the fourteenth IGBT module Q18 are commonly connected to the first end of the sixth AC port B6 of the fourth bidirectional inverter module 203, the first ends of the eleventh IGBT module Q15 and the thirteenth IGBT module Q17 are commonly connected to the first end of the sixth DC port A6 of the fourth bidirectional inverter module 203, and the second ends of the twelfth IGBT module Q16 and the fourteenth IGBT module Q18 are commonly connected to the second end of the sixth DC port A6 of the fourth bidirectional inverter module 203.

[0059] In the second voltage conversion module 204, the third switching switch 211 is the switch S3, the second inductor 212 is the inductor L2, the third switching transistor 213 is the switching transistor Q19, the fourth switching transistor 215 is the switching transistor Q20, the fourth switching switch 214 is the switch S4, the third common terminal a3 of the switch S3 is the first end of the seventh DC port A7, the fifth switching terminal a4 of the switch S3 is respectively connected to the first end of the inductor L2 and the eighth switching terminal b5 of the switch S4, the sixth switching terminal a5 of the switch S3 is respectively connected to the second end of the switching transistor Q19 and the seventh switching terminal b4 of the switch S4, the second end of the inductor L2 is respectively connected to the first end of the switching transistor Q19 and the first end of the switching transistor Q20, the second end of the switching transistor Q20 is the second end of the seventh DC port A7 and the second end of the eighth DC port A8, and the fourth common terminal b3 of the switch S4 is the first end of the eighth DC port A8.

[0060] As an example, through a device communication protocol (traditionally using CAN, RS485, etc.) or a display panel, the discharging device is set as the master device and the charging device is set as the slave device. The master device is connected to the DC ports BAT1+ and BAT1- (the first DC port), and the slave device is connected to the DC ports BAT2+ and BAT2- (the fifth DC port). After the master device reads the information of the slave device, it sends the HV voltage value to the slave device. The slave device adjusts the buckboost circuit through HV to charge the battery. For example, if the batteries of the master device and the slave device are both 48V systems, the master device determines that the output HV voltage is equal to (Vbat×N2 / N1)+K, where K is a constant; the BOOSTBUCK circuit connected to the master device is in the boost state. After receiving the HV voltage, the BOOSTBUCK circuit connected to the slave device is in the buck state to charge the slave device. If the voltage of the master device is less than that of the slave device, the master device is a 24V system and the slave device is a 48V system. The master device outputs an HV voltage equal to (Vbat×N2 / N1)+K, and the BOOSTBUCK circuit connected to the master device is in the boost state. After receiving the HV voltage, the BOOSTBUCK circuit connected to the slave device is in the buck state to charge the slave device. If the voltage of the master device is greater than that of the slave device, the master device is a 48V system and the slave device is a 24V system. The master device outputs an HV voltage equal to ((main Vbat + slave Vbat) / 2)×(N2 / N1), where main Vbat is the voltage of the DC port connected to the master device and slave Vbat is the voltage of the DC port connected to the slave device. The BOOSTBUCK circuit connected to the master device is in the buck state. After receiving the HV voltage, the BOOSTBUCK circuit connected to the slave device is in the buck state to charge the slave device. In this technical solution, when the voltage levels of the master and slave devices are inconsistent, by setting the output high-voltage of the master device as the average value of the battery voltages of the master device and the slave device multiplied by the transformer turns ratio ((main Vbat + slave Vbat) / 2)×(N2 / N1), the voltage adaptive matching between the high-voltage and low-voltage systems is achieved. When the voltage of the master device is higher than that of the slave device (for example, the master device is 48V and the slave device is 24V), the BOOSTBUCK circuit at the master device end automatically enters the buck mode to output a stable HV voltage, and the BOOSTBUCK circuit at the slave device end enters the buck mode to achieve safe charging. This solution effectively avoids voltage impact and energy backflow, realizes intelligent mutual charging and energy coordination between different voltage systems, and improves system compatibility and operation efficiency.

[0061] Embodiment 2 This Embodiment 2 provides a control method for the wide-voltage bidirectional charge and discharge device provided in Embodiment 1. The control method includes: Controlling the first voltage conversion module to switch to the boost conversion state or the buck conversion state according to the charge and discharge state, the voltage of the first DC port, the voltage of the fourth DC port, and the turns ratio of the first transformer.

[0062] Further, when in the charging state, a first voltage is input to the fourth DC port, and a second voltage is output from the first DC port. The first voltage conversion module is controlled to switch to a boost conversion state or a buck conversion state according to the charge and discharge state, the voltage of the first DC port, the voltage of the fourth DC port, and the turns ratio of the first transformer, including: When in the charging state, when the ratio between the second voltage and the first voltage is greater than the turns ratio of the first secondary coil and the first primary coil of the first transformer, control the first voltage conversion module to switch to the buck conversion state; when the ratio between the second voltage and the first voltage is less than the turns ratio of the first secondary coil and the first primary coil of the first transformer, control the first voltage conversion module to switch to the boost conversion state.

[0063] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A wide voltage bidirectional charge and discharge device, characterized in that: include: A first bidirectional inverter module, comprising a first DC port and a first AC port, for bidirectionally converting a DC voltage into an AC voltage; A first transformer, comprising a first primary coil and a first secondary coil, wherein the first primary coil is connected to a first AC port of the first bidirectional inverter module; A second bidirectional inverter module, comprising a second AC port and a second DC port, wherein the second AC port is connected to the first secondary coil to perform bidirectional conversion between AC voltage and DC voltage; a first voltage conversion module, comprising a third DC port and a fourth DC port, wherein the third DC port is connected to the second DC port and is used for switching between the third DC port and the fourth DC port to perform a step-up conversion state or a step-down conversion state; A control module, which is respectively connected to the first bidirectional inverter module, the second bidirectional inverter module and the first voltage conversion module, and is used to control the first voltage conversion module to switch to a step-up conversion state or a step-down conversion state according to a charging and discharging state, a voltage of the first DC port, a voltage of the fourth DC port, and a turns ratio of the first transformer.

2. The wide voltage bidirectional charge and discharge device according to claim 1, characterized in that: When in the charging state, the fourth DC port inputs a first voltage, and the first DC port outputs a second voltage, and the control module is used to control the first voltage conversion module to switch to a step-down conversion state when the ratio between the second voltage and the first voltage is greater than the turns ratio between the first secondary coil and the first primary coil of the first transformer; The control module is further configured to control the first voltage conversion module to switch to a boost conversion state when a ratio between the second voltage and the first voltage is smaller than a turns ratio between a first secondary coil and a first primary coil of the first transformer.

3. The wide voltage bidirectional charge and discharge device according to claim 1, characterized in that: When in the discharge state, the first DC port inputs a third voltage, and the fourth DC port outputs a fourth voltage, and the control module is used to control the first voltage conversion module to switch to a boost conversion state when the ratio between the fourth voltage and the third voltage is greater than the turns ratio between the first secondary coil and the first primary coil of the first transformer; The control module is further configured to control the first voltage conversion module to switch to a step-down conversion state when a ratio between the fourth voltage and the third voltage is smaller than a turns ratio between the first secondary coil and the first primary coil of the first transformer.

4. The wide voltage bidirectional charge and discharge device according to claim 2 or 3, characterized in that: The first voltage conversion module includes a first switching switch, a first inductor, a first switching tube, a second switching tube and a second switching switch. The first common end of the first switching switch is the first end of the third DC port. The first switching end of the first switching switch is respectively connected to the first end of the first inductor and the fourth switching end of the second switching switch. The second switching end of the first switching switch is respectively connected to the second end of the first switching tube and the third switching end of the second switching switch. The second end of the first inductor is respectively connected to the first end of the first switching tube and the first end of the second switching tube. The second end of the second switching tube is the second end of the third DC port and the second end of the fourth DC port. The second common end of the second switching switch is the first end of the fourth DC port.

5. The wide voltage bidirectional charge and discharge device according to claim 4, characterized in that: The control module controls the first common end of the first switch to connect to the first switch end of the first switch, and controls the second common end of the second switch to connect to the third switch end of the second switch, so as to control the first voltage conversion module to switch to a step-down conversion state.

6. The wide voltage bidirectional charge and discharge device according to claim 4, characterized in that: The control module controls the first common end of the first switch to connect to the second switch end of the first switch, and controls the second common end of the second switch to connect to the fourth switch end of the second switch, so as to control the first voltage conversion module to switch to a boost conversion state.

7. The wide voltage bidirectional charge and discharge device according to claim 1, characterized in that: The wide voltage bidirectional charge and discharge device further comprises: A third bidirectional inverter module, comprising a fifth DC port and a fifth AC port, for bidirectionally converting a DC voltage into an AC voltage; A second transformer, comprising a second primary coil and a second secondary coil, wherein the second primary coil is connected to a fifth AC port of the third bidirectional inverter module; a fourth bidirectional inverter module, comprising a sixth AC port and a sixth DC port, wherein the sixth AC port is connected to the second secondary coil to perform bidirectional conversion between AC voltage and DC voltage; The second voltage conversion module includes a seventh DC port and an eighth DC port, wherein the seventh DC port is connected to the sixth DC port, and the eighth DC port is connected to the fourth DC port, and is used for switching between the seventh DC port and the eighth DC port to perform a step-up conversion state or a step-down conversion state.

8. The wide voltage bidirectional charge and discharge device according to claim 7, characterized in that: The second voltage conversion module includes a third switch, a second inductor, a third switch tube, a fourth switch tube and a fourth switch. The third common end of the third switch is the first end of the fifth DC port. The fifth switch end of the third switch is respectively connected to the first end of the second inductor and the eighth switch end of the fourth switch. The sixth switch end of the third switch is respectively connected to the second end of the third switch tube and the seventh switch end of the fourth switch. The second end of the second inductor is respectively connected to the first end of the third switch tube and the first end of the fourth switch tube. The second end of the fourth switch is the second end of the third DC port and the second end of the fourth DC port. The fourth common end of the fourth switch is the first end of the fourth DC port.

9. A control method based on the wide voltage bidirectional charge and discharge device according to claim 1, characterized in that: The control method comprises: The first voltage conversion module is controlled to switch to a step-up conversion state or a step-down conversion state according to the charge and discharge state, the voltage of the first DC port, the voltage of the fourth DC port, and the turns ratio of the first transformer.

10. The control method according to claim 9, characterized in that: When in the charging state, the fourth DC port inputs a first voltage, and the first DC port outputs a second voltage, and the first voltage conversion module is controlled to switch to a step-up conversion state or a step-down conversion state according to the charging and discharging state, the voltage of the first DC port, the voltage of the fourth DC port, and the turns ratio of the first transformer, including: When the ratio between the second voltage and the first voltage is greater than the turns ratio between the first secondary coil and the first primary coil of the first transformer, the first voltage conversion module is controlled to switch to the step-down conversion state; when the ratio between the second voltage and the first voltage is less than the turns ratio between the first secondary coil and the first primary coil of the first transformer, the first voltage conversion module is controlled to switch to the step-up conversion state.

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