Wide voltage bidirectional charging and discharging device and control method thereof

Abstract

The application 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 transformer, a second bidirectional inversion module, a third bidirectional inversion module, a first switch module, a second switch module, a first voltage conversion module, a second voltage conversion module, a third switch module and a control module. The control module controls the switch states of the first switch module, the second switch module and the third switch module to switch to a parallel mode or a series mode. The technical scheme can adapt to wide-voltage input and output requirements and improve the scene adaptation capability of the system. Through the coordinated control of the control module on the switch unit, flexible switching between the series mode and the parallel mode is realized, and the efficiency and safety of power transmission are enhanced.

Description

TECHNICAL FIELD

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

[0002] With the wide application of renewable energy and the rapid development of electric vehicles and distributed energy storage, the market has put forward higher requirements for DCDC charging and discharging devices with high efficiency and wide adaptability. Traditional DCDC modules are mostly single topology structures, and the working mode is fixed, so it is difficult to simultaneously meet the charging and discharging requirements of high-voltage small current and low-voltage large current. Such devices often show insufficient compatibility and poor adaptability when facing different energy types (such as solar panels, charging piles, and mains inverters) and changing application scenarios (such as outdoor power supply, cold chain transportation, and power guarantee).

[0003] In addition, existing charging and discharging devices generally have the defects of narrow input and output voltage range, inability to operate at constant power, complex circuit structure, and high cost. For example, in a distributed energy system, there may be large voltage fluctuations on the input side of the system, and the output side load (such as a storage battery) may also require stable power supply, which poses a challenge to the wide voltage input and output range and dynamic response capability of the DCDC module. Some systems attempt to expand the use range by stacking multiple DCDC modules or external voltage conversion devices, but this usually results in increased system complexity, increased loss, and reduced reliability. SUMMARY

[0004] The embodiments of the present application provide a wide-voltage bidirectional charging and discharging device and a control method thereof to solve the above technical problems.

[0005] The first aspect of the embodiments of the present application provides a wide-voltage bidirectional charging and discharging device, comprising:

[0006] a first bidirectional inverter module, comprising a first direct current port and a first alternating current port, for bidirectional conversion of direct current voltage and alternating current voltage;

[0007] a transformer, comprising a first primary coil, a first secondary coil, and a second secondary coil, the first primary coil being connected to the first alternating current port of the first bidirectional inverter module;

[0008] a second bidirectional inverter module, comprising a second alternating current port and a second direct current port, the second alternating current port being connected to the first secondary coil to bidirectionally convert alternating current voltage and direct current voltage;

[0009] a third bidirectional inverter module, comprising a third alternating current port and a third direct current port, the third alternating current port being connected to the second secondary coil to bidirectionally convert alternating current voltage and direct current voltage;

[0010] a first switch module, one end of which is connected to the second DC port, and the other end of which is connected to the third DC port;

[0011] a second switch module, a common end of which is connected to the second DC port, and a switching end of which is connected to the third DC port;

[0012] a first voltage conversion module, which comprises a fourth DC port and a fifth DC port, the fourth DC port being connected to the second DC port and the third DC port respectively, and being used for switching between a step-up conversion state and a step-down conversion state between the fourth DC port and the fifth DC port;

[0013] a second voltage conversion module, which comprises a sixth DC port and a seventh DC port, the sixth DC port being connected to the second DC port and the third DC port respectively, and being used for switching between a step-up conversion state and a step-down conversion state between the sixth DC port and the seventh DC port;

[0014] a third switch module, a common end of which is connected to the third DC port, and a switching end of which is connected to the fifth DC port and the second DC port respectively;

[0015] a control module, which is connected to the first switch module, the second switch module and the third switch module respectively, and is used for controlling switching states of the first switch module, the second switch module and the third switch module respectively, so as to switch to a parallel mode or a series mode.

[0016] Optionally, a first switching end of the second switch module is connected to one end of the third DC port, a second switching end of the second switch module is connected to the other end of the third DC port, one end of the fourth DC port is connected to one end of the second DC port, the other end of the fourth DC port is connected to the other end of the third DC port, one end of the sixth DC port is connected to one end of the second DC port, the other end of the sixth DC port is connected to the other end of the third DC port, a first switching end of the third switch module is connected to one end of the fifth DC port, and a second switching end of the third switch module is connected to one end of the second DC port.

[0017] When in the parallel mode, the second bidirectional inverter module and the third bidirectional inverter module are connected in parallel, and the first voltage conversion module and the second voltage conversion module are connected in parallel; when in the series mode, the second bidirectional inverter module and the third bidirectional inverter module are connected in series, and the first voltage conversion module and the second voltage conversion module are connected in series.

[0018] Optionally, the control module controls the first switch module to be in the conducting state, the common terminal of the second switch module is connected to the first switching terminal of the second switch module, and the common terminal of the third switch module is connected to the first switching terminal of the third switch module, and the parallel mode is switched to.

[0019] Optionally, the control module controls the first switch module to be in the non-conducting state, the common terminal of the second switch module is connected to the second switching terminal of the second switch module, and the common terminal of the third switch module is connected to the second switching terminal of the third switch module, and the series mode is switched to.

[0020] Optionally, the first voltage conversion module comprises a first inductor, a first switch tube and a second switch tube, one end of the first switch tube is one end of the fourth DC port, the second end of the first switch tube is connected to one end of the first inductor and one end of the second switch tube respectively, the other end of the first inductor is one end of the fifth DC port, and the other end of the second switch tube is the other end of the fourth DC port and the other end of the fifth DC port respectively.

[0021] Optionally, the second voltage conversion module comprises a second inductor, a third switch tube and a fourth switch tube, one end of the third switch tube is one end of the sixth DC port, the second end of the third switch tube is connected to one end of the second inductor and one end of the fourth switch tube respectively, the other end of the second inductor is one end of the seventh DC port, and the other end of the fourth switch tube is the other end of the sixth DC port and the other end of the seventh DC port respectively.

[0022] Optionally, the wide-voltage bidirectional charging and discharging device further comprises a first capacitor and a second capacitor, the first capacitor is connected between the second DC ports, and the second capacitor is connected between the third DC ports, when in the parallel mode, the first capacitor and the second capacitor are connected in parallel, and when in the series mode, the first capacitor and the second capacitor are connected in series.

[0023] The second aspect of the embodiment of the application provides a control method of the wide-voltage bidirectional charging and discharging device based on the first aspect, and the control method comprises the following steps:

[0024] controlling the switching state of the first switch module, the second switch module and the third switch module respectively, so as to switch to the parallel mode or the series mode.

[0025] When in the parallel mode, the second bidirectional inversion module and the third bidirectional inversion module are connected in parallel, and the first voltage conversion module and the second voltage conversion module are connected in parallel; when in the series mode, the second bidirectional inversion module and the third bidirectional inversion module are connected in series, and the first voltage conversion module and the second voltage conversion module are connected in series.

[0026] Optionally, the switching states of the first switch module, the second switch module and the third switch module are controlled respectively to switch to the parallel mode, including:

[0027] When the first switch module is in the on state, the common end of the second switch module is connected to the first switching end of the second switch module, and the common end of the third switch module is connected to the first switching end of the third switch module, the parallel mode is switched to.

[0028] Optionally, the switching states of the first switch module, the second switch module and the third switch module are controlled respectively to switch to the series mode, including:

[0029] When the first switch module is in the off state, the common end of the second switch module is connected to the second switching end of the second switch module, and the common end of the third switch module is connected to the second switching end of the third switch module, the series mode is switched to.

[0030] Optionally, the wide-voltage bidirectional charging and discharging device further comprises a first capacitor and a second capacitor, the first capacitor is connected between the second DC ports, and the second capacitor is connected between the third DC ports.

[0031] The control method further comprises: when in the parallel mode, connecting the first capacitor and the second capacitor in parallel; when in the series mode, connecting the first capacitor and the second capacitor in series.

[0032] The technical effects of the embodiment of the application are as follows: by constructing a structure including multiple bidirectional inversion modules, voltage conversion modules and switchable series-parallel connection, the wide-voltage input and output requirements can be met, and the scene adaptation capability of the system is improved; by the coordinated control of the control module on the switching unit, the flexible switching between the series mode and the parallel mode is realized, and the efficiency and safety of power transmission are enhanced; further combined with the constant power control mechanism, the energy scheduling stability of the energy storage system is effectively improved; at the same time, the system structure is compact and the control is flexible, and has good expansion capability, and the technical problems of the existing charging and discharging system in the aspects of narrow voltage range, complex structure and poor adaptability are significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the description of the embodiments of the present application. Obviously, the drawings in the following description only some of the embodiments of the present application, and all other embodiments obtained by those of ordinary skill in the art without creative labor based on these drawings are within the scope of the present application.

[0034] Figure 1 is a structure schematic diagram of a wide voltage bidirectional charge and discharge device provided by the embodiment one of the present application;

[0035] Figure 2 is a partial circuit diagram of the wide voltage bidirectional charge and discharge device provided by the embodiment one of the present application;

[0036] Figure 3 is a partial circuit diagram of the wide voltage bidirectional charge and discharge device provided by the embodiment one of the present application;

[0037] Figure 4 is a circuit diagram of the wide voltage bidirectional charge and discharge device provided by the embodiment one of the present application in parallel mode;

[0038] Figure 5 is a circuit diagram of the wide voltage bidirectional charge and discharge device provided by the embodiment one of the present application in series mode;

[0039] In the figure: 101, first bidirectional inversion module; 102, transformer; 103, second bidirectional inversion module; 104, third bidirectional inversion module; 105, first switch module; 106, second switch module; 107, first voltage conversion module; 108, second voltage conversion module; 109, third switch module; 110, control module. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of the present application.

[0041] It should be understood that the present application can be implemented in different forms, and should not be interpreted as being limited to the embodiments presented here. On the contrary, these embodiments are provided to make the disclosure complete and complete, and to fully convey the scope of the present application to those skilled in the art. In the drawings, the size and relative size of the layers and regions may be exaggerated for clarity throughout the same reference signs represent the same elements.

[0042] It will be understood that when an element or layer is referred to as being "on" or "connected to" or "coupled to" another element or layer, it can be directly on, connected or coupled to the other element or layer, or intervening elements or layers can be present. In contrast, when an element is referred to as being "directly on," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present application.

[0043] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of 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 thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0044] For a thorough understanding of the present application, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which:

[0045] Embodiment One

[0046] Embodiment One provides a wide voltage bidirectional charging and discharging device, as shown in the following figure, comprising: Figure 1

[0047] A first bidirectional inverter module 101, comprising a first DC port and a first AC port, for bidirectional conversion of DC voltage and AC voltage;

[0048] A transformer 102, comprising a first primary coil, a first secondary coil and a second secondary coil, the first primary coil being connected to the first AC port of the first bidirectional inverter module 101;

[0049] ​a second bidirectional inversion module 103, comprising a second AC port and a second DC port, the second AC port being connected to the first secondary coil to convert AC voltage and DC voltage bidirectionally;

[0050] a third bidirectional inversion module 104, comprising a third AC port and a third DC port, the third AC port being connected to the second secondary coil to convert AC voltage and DC voltage bidirectionally;

[0051] a first switch module 105, one end of which is connected to one end of the second DC port, and the other end of which is connected to one end of the third DC port;

[0052] a second switch module 106, the common end of which is connected to the other end of the second DC port, and the switching end of which is connected to the third DC port, wherein the first switching end of the second switch module 106 is connected to one end of the third DC port, and the second switching end of the second switch module 106 is connected to the other end of the third DC port;

[0053] a first voltage conversion module 107, comprising a fourth DC port and a fifth DC port, the fourth DC port being connected to the second DC port and the third DC port respectively, one end of the fourth DC port being connected to one end of the second DC port, and the other end of the fourth DC port being connected to the other end of the third DC port, for switching between step-up conversion state and step-down conversion state between the fourth DC port and the fifth DC port;

[0054] a second voltage conversion module 108, comprising a sixth DC port and a seventh DC port, the sixth DC port being connected to the second DC port and the third DC port respectively, one end of the sixth DC port being connected to one end of the second DC port, and the other end of the sixth DC port being connected to the other end of the third DC port, for switching between step-up conversion state and step-down conversion state between the sixth DC port and the seventh DC port;

[0055] a third switch module 109, the common end of which is connected to the other end of the third DC port, and the switching end of which is connected to the fifth DC port and the second DC port respectively, the first switching end of the third switch module 109 being connected to one end of the fifth DC port, and the second switching end of the third switch module 109 being connected to one end of the second DC port;

[0056] a control module 110, connected to the first switch module 105, the second switch module 106 and the third switch module 109 respectively, for controlling the switching state of the first switch module 105, the second switch module 106 and the third switch module 109 respectively, to switch to parallel mode or series mode;

[0057] When in the parallel mode, the second bidirectional inversion module 103 and the third bidirectional inversion module 104 are connected in parallel, and the first voltage conversion module 107 and the second voltage conversion module 108 are connected in parallel; when in the series mode, the second bidirectional inversion module 103 and the third bidirectional inversion module 104 are connected in series, and the first voltage conversion module 107 and the second voltage conversion module 108 are connected in series.

[0058] The first bidirectional inversion module 101 has bidirectional energy conversion capability, which can convert DC voltage into AC voltage, and can also rectify AC voltage into DC voltage, supporting bidirectional operation of charging and discharging. The first DC port can be connected to a DC power supply (such as a battery or a DCDC module), and the first AC port is connected to the transformer 102, which is used to realize energy exchange with the power grid or other AC systems. The transformer 102 includes a first primary coil, a first secondary coil and a second secondary coil, which are used to realize isolation and transformation between different voltage levels. The first primary coil is connected to the first bidirectional inversion module 101, and the AC power is transmitted to the two secondary coils through electromagnetic coupling, which are respectively provided to the second bidirectional inversion module 103 and the third bidirectional inversion module 104, supporting voltage transformation and multi-end output. The second AC port of the second bidirectional inversion module 103 is connected to the first secondary coil, and the second DC port is a DC output / input channel of the system, which can be connected to an energy storage device or a load, supporting energy absorption (charging) from the AC side or DC feedback to AC (discharging) operation. The third bidirectional inversion module 104 has similar structure and function to the second bidirectional inversion module 103, but is connected to the second secondary coil of the transformer 102, thereby realizing an independent bidirectional energy conversion channel; through series and parallel switching with the second bidirectional inversion module 103, the voltage and current output range of the system can be expanded. The first switch module 105 is used to connect the DC ports of the second bidirectional inversion module 103 and the third bidirectional inversion module 104, realizing part of the closed path in parallel or series structure; its conduction state participates in determining the final system connection topology. The second switch module 106 is a bidirectional switching switch, which has two switching ends and allows different ends of the second DC port and the third DC port to be connected. According to the instruction of the control module 110, it can be switched to parallel mode (current superposition) or series mode (voltage superposition). The first voltage conversion module 107 is used to step up or step down the voltage in different modes, realizing wider range of output adaptation. Through control, the step-up path or step-down path can be selected, and as part of the parallel or series path, the overall power flow is adjusted. The second voltage conversion module 108 has the same function as the first voltage conversion module 107, providing another adjustable step-up or step-down channel. When the two modules work together, they allow more stable power conversion and voltage balance in series or parallel state. The third switch module 109 is located on the output path of the voltage conversion module, and its common end is connected to the seventh DC port, which is used to switch the fifth DC port or the second DC port, thereby determining the connection direction or working mode of the voltage conversion module, and is one of the key nodes for building series / parallel topology.The control module 110 is a core logic control unit for controlling the on and off states of the first switch module 105, the second switch module 106 and the third switch module 109 according to system running state, load demand, voltage and current monitoring and other information, and then dynamically switching the series or parallel running mode of the system to realize automatic adaptive control of high and low voltage bidirectional charging and discharging.

[0059] The technical effect of the technical solution provided by the embodiment one is that through the cooperative matching of the bidirectional inverter module and the voltage conversion module, flexible work is supported in the high-voltage small-current and low-voltage large-current scene, the input and output voltage adaptation range of the system is significantly improved, and the needs of different energy storage devices, power types (such as mains, photovoltaic, charging pile) and various application scenarios (such as outdoor power supply, cold chain transportation) are met. By setting multiple switch modules and the control module 110, the series or parallel mode can be automatically switched according to real-time running demand, the power transmission of different voltage and current levels can be adapted, and the system running efficiency and module utilization rate can be improved. Multiple bidirectional inverter modules all support forward and reverse energy flow, and can realize constant power control in the charging and discharging process in cooperation with the voltage conversion module, adapt to the needs of the battery end to constant power supply, and improve the accuracy and safety of energy management. Compared with the traditional way of expanding the voltage range by stacking multiple DCDC modules, the present application adopts a shared architecture constructed by a multi-winding transformer 102 and multiple inverters, reduces the system complexity, reduces the number of devices, and improves the integration and reliability of the system. The control module 110 can dynamically control the state of multiple switch modules according to load demand, voltage level and other parameters to realize flexible scheduling in multiple working modes and adapt to the expansion needs of future distributed energy storage and smart grid. The present application can adapt to wide range of voltage input and output needs, improve the scene adaptation ability of the system by constructing multiple bidirectional inverter modules, voltage conversion modules and switchable series and parallel structures; through the coordinated control of the control module 110 on the switching unit, the flexible switching of series and parallel modes is realized, the efficiency and safety of power transmission are enhanced; further combined with the constant power control mechanism, the energy scheduling stability of the energy storage system is effectively improved; at the same time, the system structure is compact and the control is flexible, which has good expansion ability, and significantly improves the technical problems of the existing charging and discharging system in terms of narrow voltage range, complex structure and poor adaptability.

[0060] As an implementation manner, the control module 110 controls the first switch module 105 to be in the on state, the common end of the second switch module 106 is connected to the first switching end of the second switch module 106 of the second switch module 106, and the common end of the third switch module 109 is connected to the first switching end of the second switch module 106 of the third switch module 109, and the parallel mode is switched to.

[0061] The control module 110 is configured to control the plurality of switch modules to switch the connection mode of the system. When the system needs to enter the parallel mode, the control module 110 performs the following control operation: controlling the first switch module 105 to be in the on state, connecting the first DC terminals of the second bidirectional inversion module 103 and the third bidirectional inversion module 104 to each other; controlling the second switch module 106 to connect the common terminal to the first switching terminal, so that the second DC terminals of the second bidirectional inversion module 103 and the third bidirectional inversion module 104 are also connected together to form a complete parallel structure; and controlling the third switch module 109 to connect the common terminal to the first switching terminal to connect the first voltage conversion module 107 and the second voltage conversion module 108 in parallel for voltage conversion in the parallel mode. Through the above switching operation, the second bidirectional inversion module 103 and the third bidirectional inversion module 104 form a parallel relationship on the DC side, and the corresponding voltage conversion modules also work in the parallel path, realizing efficient operation of the system under the condition of low-voltage and large-current load.

[0062] The technical effect of the embodiment is that the control module 110 cooperatively controls the plurality of switch modules, so that the bidirectional inversion module and the voltage conversion module can be flexibly switched to the parallel mode, thereby realizing efficient and stable output under the condition of low-voltage and large-current, enhancing the adaptability of the system under the condition of wide-voltage input and output, and improving the output power density and overall energy efficiency of the charging and discharging equipment.

[0063] As an embodiment, when the control module 110 controls the first switch module 105 to be in the off state, the common terminal of the second switch module 106 is connected to the second switching terminal of the second switch module 106, and the common terminal of the third switch module 109 is connected to the second switching terminal of the second switch module 106, the system is switched to the series mode.

[0064] The control module 110 can also be used to switch the system to a series mode. When the second bidirectional inversion module 103 and the third bidirectional inversion module 104 need to be connected in series, the control module 110 performs the following control logic: control the first switch module 105 to be in an open state, disconnect the direct connection between the second DC port and the third DC port, and avoid short circuiting; control the second switch module 106 to connect its common end to its second switching end, connect one end of the second bidirectional inversion module 103 to the opposite end of the third bidirectional inversion module 104, and thus realize the series connection of the two modules on the DC side; control the third switch module 109 to connect its common end to its second switching end, to connect the first voltage conversion module 107 and the second voltage conversion module 108 in series, for cooperative voltage regulation and improved output voltage level. In this control state, the DC channels of the second bidirectional inversion module 103 and the third bidirectional inversion module 104 are connected in series end to end, and the corresponding voltage conversion modules also work in series, thus providing higher output voltage and being suitable for high-voltage small-current load scenarios.

[0065] The technical effect of the embodiment is that, through the combined control of the control module 110 on the first switch module 105, the second switch module 106, and the third switch module 109, the DC side of the second bidirectional inversion module 103 and the third bidirectional inversion module 104 can be connected in series, and the voltage conversion modules can be driven to work in series, thus effectively improving the output voltage of the system, meeting the needs of high-voltage application scenarios, while maintaining the constant power output capability and enhancing the wide-voltage output range and application flexibility of the system.

[0066] As an embodiment, the first voltage conversion module 107 includes a first inductor, a first switch tube, and a second switch tube. The first end of the first switch tube is one end of the fourth DC port. The second end of the first switch tube is connected to one end of the first inductor and one end of the second switch tube, respectively. The other end of the first inductor is one end of the fifth DC port. The other end of the second switch tube is the other end of the fourth DC port and the other end of the fifth DC port, respectively.

[0067] The first inductor stores and releases energy in the process of voltage conversion, plays a role in smoothing current and controlling energy transmission, and is a key energy conversion device in the BUCK-BOOST topology. The first switch mainly controls the on-off of the current, and its first end is connected to the fifth DC port (usually the high-voltage side), and its second end is connected to one end of the inductor and the second switch, which is used to control the establishment of the voltage conversion path. The second switch cooperates with the first switch to form a complementary drive and controls the opening of the energy release path. When the second switch is turned on, a path from the negative electrode to the load is established, and at the same time, a symmetrical synchronous rectification structure is formed with the first switch to improve the conversion efficiency. Under the drive of the control module 110, the first switch and the second switch are alternately turned on to realize the switching of the voltage conversion state between the fourth DC port and the fifth DC port. This structure supports bidirectional power flow and meets the charging and discharging requirements between devices of different voltage levels.

[0068] The technical effect of the embodiment is that efficient voltage conversion between the fourth DC port and the fifth DC port is realized by inductive energy storage and switch switching. This voltage conversion module not only has a simple structure, but also has the ability of bidirectional conversion of voltage conversion, which is suitable for different voltage adaptation requirements of the system in series and parallel modes, and enhances the flexibility and energy efficiency ratio of the entire charging and discharging device under wide voltage operation.

[0069] As an embodiment, the wide-voltage bidirectional charging and discharging device further comprises a first capacitor and a second capacitor, the first capacitor is connected between the second DC ports, and the second capacitor is connected between the third DC ports. When in parallel mode, the first capacitor and the second capacitor are connected in parallel; when in series mode, the first capacitor and the second capacitor are connected in series.

[0070] The wide-voltage bidirectional charging and discharging device further comprises a first capacitor and a second capacitor, which are used as DC-link capacitances of the system to stabilize voltage, absorb current ripple, and improve system reliability. The control module 110 controls the switching state to realize the following two working modes: in parallel mode, the control module 110 controls the second switch module 106 and the third switch module 109 to connect the two ends of the first capacitor and the second capacitor correspondingly, so that the capacitors are connected in parallel, the total capacitance capacity is increased, which helps to support large current output and reduce output ripple; in series mode, the control module 110 connects the negative electrode and the positive electrode of the first capacitor and the second capacitor in sequence, so that the two capacitors work in series, improve the voltage bearing capacity, and meet the stable demand of high-voltage output. The configuration cooperates with the series-parallel mode of the bidirectional inverter module to ensure that the system has good dynamic response capability and power stability in different working states.

[0071] The technical advantages of this implementation are as follows: by setting a first capacitor and a second capacitor that can be configured in series and parallel, the system can obtain a larger filter capacitor capacity in parallel mode to reduce high-frequency ripple, and obtain a higher voltage withstand capability in series mode to adapt to high-voltage output scenarios. This achieves dual optimization of bus stability and ripple suppression performance under a wide voltage range, and improves the stability and reliability of the system in high and low voltage bidirectional charging and discharging scenarios.

[0072] The following describes this embodiment through a specific circuit structure: Figure 2 and Figure 3As shown, the first bidirectional inversion module 101 includes a first MOS tube Q1, a second MOS tube Q2, a third MOS tube Q3, and a fourth MOS tube Q4. The second bidirectional inversion module 103 includes a fifth MOS tube Q5, a sixth MOS tube Q6, a seventh MOS tube Q7, and an eighth MOS tube Q8. The third bidirectional inversion module 104 includes a ninth MOS tube Q9, a tenth MOS tube Q10, an eleventh MOS tube Q11, and a twelfth MOS tube Q12. The first voltage conversion module 107 includes a first inductor L1, the eleventh MOS tube Q11, and the twelfth MOS tube Q12. The second voltage conversion module 108 includes a second inductor L2, a thirteenth MOS tube Q13, and a fourteenth MOS tube Q14. The first switch module 105 is a switch SW1. The second switch module 106 is a switch SW2. The third switch module 109 is a switch SW3. The drain of the first MOS tube Q1 and the drain of the second MOS tube Q2 are commonly connected as a first end BAT1+ of a first direct current port of the first bidirectional inversion module 101. The source of the third MOS tube Q3 and the source of the fourth MOS tube Q4 are commonly connected as a second end BAT1- of the first direct current port of the first bidirectional inversion module 101. The source of the first MOS tube Q1 and the drain of the third MOS tube Q3 are commonly connected to a first end of a primary coil of a transformer T1. The source of the second MOS tube Q2 and the drain of the fourth MOS tube Q4 are commonly connected to a second end of the primary coil of the transformer T1. The second end of the fifth MOS tube Q5 and the first end of the sixth MOS tube Q6 are commonly connected to a second end of a first secondary coil of the transformer T1. The second end of the seventh MOS tube Q7 and the first end of the eighth MOS tube Q8 are commonly connected to a first end of the first secondary coil of the transformer T1. The first end of the fifth MOS tube Q5 and the first end of the seventh MOS tube Q7 are commonly connected to a first end of a capacitor C1 and a first end of the switch SW1, and form a first end A of a second direct current port. The second end of the sixth MOS tube Q6 and the second end of the eighth MOS tube Q8 are commonly connected to a second end of the capacitor C1 and a common end 3 of the switch SW2, and form a second end B of the second direct current port. The second end of the ninth MOS tube Q9 and the first end of the tenth MOS tube Q10 are commonly connected to a second end of a second secondary coil of the transformer T1. The second end of the eleventh MOS tube Q11 and the first end of the twelfth MOS tube Q12 are commonly connected to a first end of the second secondary coil of the transformer T1. The first end of the ninth MOS tube Q9 and the first end of the eleventh MOS tube Q11 are commonly connected to a first end of a capacitor C2 and a second switching end 2 of the switch SW2, and form a first end C of a third direct current port. The second end of the tenth MOS tube Q10 and the second end of the twelfth MOS tube Q12 are commonly connected to a second end of the capacitor C2 and a first switching end 1 of the switch SW2, and form a second end D of the third direct current port.The first end of the thirteenth MOS Q13 is connected to the first end of the second DC port, the second end of the thirteenth MOS Q13 is connected to the first end of the fourteenth MOS Q14 and one end of the first inductor L1 respectively, the other end of the first inductor L1 is the first end of the fifth DC port, the second end of the fourteenth MOS Q14 is the second end of the fourth DC port and the second end of the fifth DC port. The first end of the fifteenth MOS Q15 is connected to the first end of the second DC port, the second end of the fifteenth MOS Q15 is connected to the first end of the sixteenth MOS Q16 and the first end of the second inductor L2 respectively, the second end of the sixteenth MOS Q16 is the second end of the sixth DC port and the second end of the seventh DC port. The first switching end of the switch SW3 is connected to the first end of the fifth DC port, the second switching end of the switch SW3 is connected to the second end of the second DC port, and the common end of the switch SW3 is connected to the first end of the seventh DC port.

[0073] As shown in Figure 4 Mode 1 is HV low voltage and large current, switch SW1 is turned on, switch SW2 is connected to common end 3 and first switching end 1, switch SW3 is connected to common end 3 and first switching end 1, two groups of buckboost circuit and DCDC circuit are connected in parallel, and the current is doubled, which can realize the function of bidirectional charge and discharge.

[0074] As shown in Figure 5 Mode 2 is HV high voltage and small current, switch SW1 is turned off, switch SW2 is connected to common end 3 and second switching end 2, switch SW3 is connected to common end 3 and second switching end 2, series connection mode is realized, voltage is doubled, bus capacitor is connected in series, through the complementary signals of the fifteenth MOS Q15 and the sixteenth MOS Q16, the fixed duty cycle output is 45%, through buckboost, the dynamic capacitor C1 voltage is equal to the capacitor C2 voltage, and the voltage sharing function is realized.

[0075] As an embodiment, for the application environment with frequent load voltage and current fluctuations or difficult to predict, in order to improve the adaptive ability of the wide voltage bidirectional charge and discharge device in different working modes, on the basis of the original control module 110, a state monitoring sub-module and a load identification sub-module are added, an intelligent prediction type working mode switching strategy is constructed, so as to realize more stable and efficient operation performance.

[0076] The state monitoring submodule is used for collecting input voltage, output voltage, current value, power fluctuation rate and temperature rise parameter of the second bidirectional inversion module 103 and the third bidirectional inversion module 104 in real time. The submodule can adopt a multi-channel ADC and data buffer logic, combined with a sliding average filter, to ensure sampling accuracy and trend tracking capability. The load identification submodule classifies the connected load in real time according to the collected output voltage / current curve shape, load dynamic response characteristics and other information, for example, judges whether it is a constant voltage type, constant current type or constant power type load, and further analyzes the load power change rate and trend. After receiving the load type and state information, the control module generates a working mode switching signal according to the following preset switching strategy: if it is detected that the output current shows a continuous growth trend, the predicted value will be above the set threshold I, and it is predicted that the system will enter a large current low voltage scene, then the control module automatically switches to the parallel mode in advance; if it is detected that the load voltage demand will be improved, the predicted value will exceed the set voltage threshold U, and it is judged as a high voltage small current application, and the switching to the series mode is advanced; if the current is in the fluctuation interval of I or U, then enter the delay confirmation state. In order to avoid frequent mode switching caused by sampling noise, short time mutation and the like, the embodiment introduces a delay confirmation mechanism, that is, once the switching decision is triggered, the system will start a preset time window (such as 3 seconds). During this period, if the predicted state is still valid, the switching is performed; if the judgment condition is eliminated, the switching action is cancelled, ensuring stable operation of the system.

[0077] The working process of the embodiment is as follows: the control module 110 regularly collects the input and output parameters of the inversion module; the load identification submodule identifies the current load type and its power trend according to the characteristic model; the predicted power demand is calculated in real time and compared with the mode switching threshold (I, U); if the predicted power enters a high current low voltage scene, the parallel mode switching signal is output; if it enters a high voltage small current scene, the series mode switching signal is output; if it is in the threshold edge area, the current mode is maintained through the delay mechanism to prevent oscillation; the control module 110 controls the first switch module 105, the second switch module 106 and the third switch module 109 to act, completing the dynamic switching of the topology structure.

[0078] The embodiment introduces state monitoring, load identification, prediction decision and delay confirmation mechanism in the control module, which can predict the power demand trend based on the load running state, and intelligently switch the series or parallel mode, realizing the upgrade control strategy from passive response to active prediction. The scheme effectively improves the running stability and response efficiency of the system in the scene of voltage / current dramatic fluctuation, reduces the device stress and energy consumption caused by frequent switching, and significantly enhances the adaptability and reliability of the wide voltage bidirectional charging and discharging device in complex working conditions.

[0079] As an implementation, to improve the control stability and system energy efficiency of the wide voltage bidirectional charging and discharging device of the application in application scenarios such as severe load fluctuation and complex lithium battery charging and discharging characteristics, the real-time power backstepping function is further arranged in the control module 110, and the voltage and current dynamic adjustment control strategy with constant power as the core target is constructed, so that the system can realize constant power control operation in parallel mode and series mode, and the stability and control accuracy of the output power are enhanced.

[0080] The control module 110 is used for sampling the output voltage U and output current I of the voltage conversion module, and calculating the current output power P=U×I. The module combines the preset battery charging and discharging curve model or load equivalent model to further predict the power change trend in the future short term (such as within hundreds of milliseconds), for example, whether the load continues to rise, whether there is a sudden drop, etc., to provide basic data for control decision. When the following trends are detected: load current rapidly rises, output voltage drops → power may overshoot; the battery is charged to the end, the voltage rises, and the output current decreases → the power may decrease; the control module will dynamically adjust the PWM duty cycle, switching frequency or phase shift angle of the first voltage conversion module and / or the second voltage conversion module, and preferentially maintain constant output power as the target, rather than simply maintaining constant voltage or current. For example, when the load voltage drops significantly, the current is appropriately limited to suppress power overshoot; when the charging current automatically decreases, the voltage is slightly increased to compensate for the power deficiency. The control module sets a maximum power threshold (such as 1000W) as the boundary for safe operation of the system. When detecting load mutation, power trend exceeding P, the control module preferentially limits the power to maintain in the constant power area, rather than outputting in constant voltage / constant current mode, thereby avoiding system instability or battery aging caused by overvoltage / overcurrent. This strategy is particularly suitable for lithium battery constant power charging tail, grid-connected inverter maximum power output, etc. In parallel or series mode, the two voltage conversion modules have their own load capacity and efficiency characteristics. The control module can dynamically allocate the total power demand to the two modules in proportion according to the current power calculation result: in parallel mode, the two voltage conversion modules share the output according to the load current proportion or efficiency priority strategy; in series mode, the control current consistency is adjusted dynamically to realize series constant power control; when one of the modules approaches the current / temperature rise upper limit, the other topology is automatically compensated to maintain constant power, improving the redundancy operation capability.

[0081] Scenario one: when the electric vehicle V2G discharges, the user side load jumps from 1kW to 1.5kW, the control module detects that the power exceeds the constant power setting value, and actively reduces the PWM duty cycle to limit the output current, so as to maintain the power within 1kW to ensure the safety of the inverter and the battery.

[0082] Scenario two: photovoltaic panel input power fluctuation, control module real-time prediction of current energy storage end power gap, adjust the output ratio of the first voltage conversion module and the second voltage conversion module, realize dynamic power compensation and whole machine constant power output.

[0083] The embodiment introduces real-time power backstepping and dynamic adjustment mechanism, so that the device can maintain the output power constant when the load or battery state changes, instead of single voltage or current control. This strategy effectively improves the energy control accuracy and stability of the system in complex application scenarios, avoids system fluctuations caused by power overshoot or decline, and is especially suitable for high-power continuity scenes such as lithium battery charging tail, electric vehicle V2G discharge, photovoltaic grid-connected output, significantly enhancing the intelligence and adaptability of the device.

[0084] Embodiment two

[0085] The embodiment two provides a control method of the wide-voltage bidirectional charging and discharging device provided in the embodiment one, and the control method comprises:

[0086] The switching states of the first switch module, the second switch module and the third switch module are controlled respectively to switch to the parallel mode or the series mode.

[0087] When in the parallel mode, the second bidirectional inverter module and the third bidirectional inverter module are connected in parallel, and the first voltage conversion module and the second voltage conversion module are connected in parallel; when in the series mode, the second bidirectional inverter module and the third bidirectional inverter module are connected in series, and the first voltage conversion module and the second voltage conversion module are connected in series.

[0088] Further, the switching states of the first switch module, the second switch module and the third switch module are controlled respectively to switch to the parallel mode, comprising:

[0089] When the first switch module is in the conductive state, the common end of the second switch module is connected to the first switching end of the second switch module, and the common end of the third switch module is connected to the first switching end of the third switch module, the parallel mode is switched to.

[0090] Further, the switching states of the first switch module, the second switch module and the third switch module are controlled respectively to switch to the series mode, comprising:

[0091] When the first switch module is in the disconnected state, the common end of the second switch module is connected to the second switching end of the second switch module, and the common end of the third switch module is connected to the second switching end of the third switch module, the series mode is switched to.

[0092] Further, the wide-voltage bidirectional charging and discharging device further comprises a first capacitor and a second capacitor, the first capacitor is connected between the second DC ports, and the second capacitor is connected between the third DC ports.

[0093] The control method further comprises: when in the parallel mode, connecting the first capacitor and the second capacitor in parallel; and when in the series mode, connecting the first capacitor and the second capacitor in series.

[0094] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit the same; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A wide voltage bidirectional charge-discharge device, characterized by, The application relates to a bidirectional DC / AC converter, which comprises the following parts: a first bidirectional inversion module, which comprises a first DC port and a first AC port, and is used for bidirectional conversion between DC voltage and AC voltage; a transformer, which comprises a first primary coil, a first secondary coil and a second secondary coil, wherein the first primary coil is connected with the first AC port of the first bidirectional inversion module; a second bidirectional inversion module, which comprises a second AC port and a second DC port, wherein the second AC port is connected with the first secondary coil, and the second bidirectional inversion module is used for bidirectional conversion between AC voltage and DC voltage; a third bidirectional inversion module, which comprises a third AC port and a third DC port, wherein the third AC port is connected with the second secondary coil, and the third bidirectional inversion module is used for bidirectional conversion between AC voltage and DC voltage; a first switch module, one end of which is connected with the second DC port, and the other end of which is connected with the third DC port; a second switch module, the common end of which is connected with the second DC port, and the switching end of which is connected with the third DC port; a first voltage conversion module, which comprises a fourth DC port and a fifth DC port, wherein the fourth DC port is connected with the second DC port and the third DC port respectively, and the first voltage conversion module is used for switching between step-up conversion state and step-down conversion state between the fourth DC port and the fifth DC port; a second voltage conversion module, which comprises a sixth DC port and a seventh DC port, wherein the sixth DC port is connected with the second DC port and the third DC port respectively, and the second voltage conversion module is used for switching between step-up conversion state and step-down conversion state between the sixth DC port and the seventh DC port; a third switch module, the common end of which is connected with the third DC port, and the switching end of which is connected with the fifth DC port and the second DC port respectively; a control module, which is connected with the first switch module, the second switch module and the third switch module respectively, and is used for controlling the switching state of the first switch module, the second switch module and the third switch module respectively, so as to switch to a parallel mode or a series mode.

2. The wide voltage bidirectional charge and discharge device of claim 1, wherein, One end of the third DC port is connected with the first switching end of the second switch module, and the other end of the third DC port is connected with the second switching end of the second switch module; one end of the second DC port is connected with one end of the fourth DC port, and the other end of the fourth DC port is connected with the other end of the third DC port; one end of the second DC port is connected with one end of the sixth DC port, and the other end of the sixth DC port is connected with the other end of the third DC port; one end of the fifth DC port is connected with the first switching end of the third switch module, and one end of the second DC port is connected with the second switching end of the third switch module. When in the parallel mode, the second bidirectional inversion module and the third bidirectional inversion module are connected in parallel, and the first voltage conversion module and the second voltage conversion module are connected in parallel; when in the series mode, the second bidirectional inversion module and the third bidirectional inversion module are connected in series, and the first voltage conversion module and the second voltage conversion module are connected in series.

3. The wide voltage bidirectional charge and discharge device of claim 1, wherein, When the control module controls the first switch module to be in the on state, the common end of the second switch module is connected to the first switching end of the second switch module, and the common end of the third switch module is connected to the first switching end of the third switch module, the parallel mode is switched to; When the control module controls the first switch module to be in the off state, the common end of the second switch module is connected to the second switching end of the second switch module, and the common end of the third switch module is connected to the second switching end of the third switch module, the series mode is switched to.

4. The wide voltage bidirectional charge and discharge device according to claim 3, wherein, The first voltage conversion module comprises a first inductor, a first switch tube and a second switch tube, a first end of the first switch tube is one end of the fourth direct current port, a second end of the first switch tube is connected to one end of the first inductor and one end of the second switch tube respectively, the other end of the first inductor is one end of the fifth direct current port, and the other end of the second switch tube is the other end of the fourth direct current port and the other end of the fifth direct current port respectively.

5. The wide voltage bidirectional charge and discharge device according to claim 3, wherein, The second voltage conversion module comprises a second inductor, a third switch tube and a fourth switch tube, a first end of the third switch tube is one end of the sixth direct current port, a second end of the third switch tube is connected to one end of the second inductor and one end of the fourth switch tube respectively, the other end of the second inductor is one end of the seventh direct current port, and the other end of the fourth switch tube is the other end of the sixth direct current port and the other end of the seventh direct current port respectively.

6. The wide voltage bidirectional charge and discharge device of claim 2, wherein, The wide-voltage bidirectional charging and discharging device further comprises a first capacitor and a second capacitor, the first capacitor is connected between the second direct current ports, and the second capacitor is connected between the third direct current ports; when in the parallel mode, the first capacitor and the second capacitor are connected in parallel; when in the series mode, the first capacitor and the second capacitor are connected in series.

7. A control method of the wide-voltage bidirectional charge-discharge device according to claim 1, characterized by, The control method comprises: Controlling the switching states of the first switch module, the second switch module and the third switch module respectively to switch to the parallel mode or the series mode; When in the parallel mode, the second bidirectional inversion module and the third bidirectional inversion module are connected in parallel, and the first voltage conversion module and the second voltage conversion module are connected in parallel; when in the series mode, the second bidirectional inversion module and the third bidirectional inversion module are connected in series, and the first voltage conversion module and the second voltage conversion module are connected in series.

8. The control method according to claim 7, characterized by, Controlling the switching states of the first switch module, the second switch module and the third switch module respectively to switch to the parallel mode comprises: When the first switch module is controlled to be in a conductive state, the common end of the second switch module is connected to the first switching end of the second switch module, and the common end of the third switch module is connected to the first switching end of the third switch module, the parallel mode is switched to.

9. The control method according to claim 7, characterized by, The switch states of the first switch module, the second switch module and the third switch module are controlled respectively to switch to the series mode, including: When the first switch module is controlled to be in a non-conductive state, the common end of the second switch module is connected to the second switching end of the second switch module, and the common end of the third switch module is connected to the second switching end of the third switch module, the series mode is switched to.

10. The control method according to claim 7, characterized by, The wide-voltage bidirectional charging and discharging device further comprises a first capacitor and a second capacitor, the first capacitor is connected between the second DC ports, and the second capacitor is connected between the third DC ports. The control method further comprises: when in the parallel mode, connecting the first capacitor and the second capacitor in parallel; and when in the series mode, connecting the first capacitor and the second capacitor in series.

Images