Battery online capacity checking system based on dual active bridge (DAB)

Abstract

The utility model discloses a battery on-line capacity checking system based on a dual active bridge (DAB), relates to the field of electric power conversion, and solves the problems that a post-stage load device has a power failure risk and an abnormal battery cannot be rapidly positioned during the capacity checking operation switching period of a conventional capacity checking device. According to the technical scheme, the system is characterized by comprising a plurality of to-be-tested batteries, an electric switch device and a plurality of capacity checking devices, a plurality of batteries to be tested are connected in series and then connected to a direct current bus through an electric switch device, each battery to be tested is connected in parallel with a capacity checking device, and the capacity checking devices are connected with the direct current bus; the capacity checking device carries out charge and discharge capacity checking on a to-be-tested battery based on a dual active bridge (DAB) structure. The capacity checking device based on the dual-active-bridge DAB topology is additionally arranged, parallel capacity checking is carried out on a single battery, online capacity checking is achieved, redundant and complex switching operation is not needed, capacity checking can be carried out on one or more batteries, the risk of load power failure can be greatly reduced, and the abnormal condition of a certain battery can be rapidly known.

Description

Technical Field

[0001] This utility model relates to the field of power conversion, and more specifically, it relates to an online battery capacity control system based on a dual active bridge (DAB). Background Technology

[0002] Battery capacity assessment devices are primarily used for real-time monitoring and evaluation of battery capacity and health status. They perform capacity-controlled discharge on batteries to simulate real-world usage scenarios and verify battery capacity and performance. Commercially available batteries typically consist of multiple cells connected in series to form a high-voltage DC circuit. A common method for battery capacity assessment is to connect the battery to a load via a switching switch for discharge capacity assessment. However, during the switching operation, downstream load equipment faces a significant risk of power loss. Furthermore, if capacity assessment fails, it is difficult to quickly and accurately identify which battery is malfunctioning. Additionally, the switching operation is complex and prone to misoperation.

[0003] Therefore, this application proposes an online battery capacity assessment system based on dual active bridge (DAB) to solve the above problems. Utility Model Content

[0004] The technical problem this application aims to solve is that existing capacity balancing devices pose a significant risk of power loss to downstream load equipment during capacity balancing operations. Furthermore, when capacity balancing fails, it is impossible to quickly and accurately identify which battery cell is malfunctioning, and the switching operations are complex and prone to misoperation. This application adds a capacity balancing device based on a dual active bridge (DAB) topology to the existing series-connected battery configuration, enabling parallel capacity balancing of individual batteries. This achieves online capacity balancing without the need for redundant and complex switching operations, allowing for the designation of one or more batteries for capacity balancing, greatly reducing the risk of load power loss, and enabling rapid identification of any abnormal battery cell.

[0005] This application is achieved through the following technical solution:

[0006] The battery online capacity verification system based on dual active bridge (DAB) includes: multiple batteries under test, an electric switch device, and multiple capacity verification devices; the multiple batteries under test are connected in series and then connected to a DC bus via the electric switch device, and a capacity verification device is connected in parallel to each battery under test, and the capacity verification device is connected to the DC bus; wherein, the capacity verification device performs charge and discharge capacity verification of the battery under test based on the dual active bridge (DAB) structure.

[0007] As one possible implementation, the nuclear capacity device includes: a reverse connection protection circuit, a dual active bridge DAB, an auxiliary power supply circuit, a control circuit, a communication circuit, and a sampling circuit; one end of the reverse connection protection circuit is used to connect to the battery under test, and the other end is connected to the dual active bridge DAB. The dual active bridge DAB is used to connect to the DC bus. Both the DC bus and the battery under test are connected to the auxiliary power supply circuit. The auxiliary power supply circuit is connected to the control circuit. The control circuit is connected to the control terminal of the dual active bridge DAB. The control circuit is also connected to the communication circuit and the sampling circuit.

[0008] As one possible implementation, the dual active bridge (DAB) includes: two full-bridge circuits, a high-frequency transformer, a high-voltage side filter capacitor, and a low-voltage side filter capacitor; the high-voltage side filter capacitor is connected to the first full-bridge circuit, the first full-bridge circuit is connected to one end of the high-frequency transformer, the other end of the high-frequency transformer is connected to the second full-bridge circuit, and the second full-bridge circuit is connected to the low-voltage side filter capacitor.

[0009] As one possible implementation, the high-voltage side filter capacitor is connected to the DC bus, and the low-voltage side filter capacitor is connected to the reverse connection protection circuit.

[0010] As one possible implementation, the full-bridge circuit consists of four MOSFETs or IGBTs.

[0011] As one possible implementation, the full-bridge circuit consists of four N-MOSFETs.

[0012] As one possible implementation, the nuclear capacity device has two states: standby or operation, and the state switching of the nuclear capacity device is determined by the state of the electric switching device.

[0013] As one possible implementation, when the electric switch is in the engaged state, the capacity storage device switches to standby state; when the electric switch is in the disengaged state, the capacity storage device switches to operating state.

[0014] As one possible implementation method, the battery under test is a lead-acid battery, a lithium battery, or a sodium battery.

[0015] As one possible implementation, the battery under test uses 24 2V dc batteries with a DC bus of 48V dc.

[0016] Compared with the prior art, this application has the following advantages: In the case of the original series battery, a capacity-capacitance device based on the dual active bridge DAB topology is added, and the capacity-capacitance device is connected in parallel with the battery to perform parallel capacity-capacitance of a single battery, realizing online capacity-capacitance. There is no need for complicated switching operations. It is also possible to specify one or more batteries for individual capacity-capacitance without affecting the operation of the entire system. This greatly reduces the risk of load power failure in traditional capacity-capacitance and can quickly identify the abnormal situation of a battery. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation on the embodiments of the present application. In the drawings:

[0018] Figure 1 A structural diagram of a battery online capacity assessment system based on a dual active bridge (DAB) provided in an embodiment of this application;

[0019] Figure 2A structural diagram of the nuclear capacity device provided in the embodiments of this application;

[0020] Figure 3 This is a structural diagram of a dual active bridge (DAB) provided in an embodiment of this application.

[0021] Figure 4 This is a schematic diagram of the forward operating waveform of a dual active bridge DAB.

[0022] Figure 5 This is a diagram showing the operating status of each component in the dual active bridge DAB during the T0 to T1 working phase.

[0023] Figure 6 This is a diagram showing the operating status of each component in the dual active bridge DAB during the T1 to T2 operating phases.

[0024] Figure 7 This is a diagram showing the operating status of each component in the dual active bridge DAB during the T2 to T3 operating phases.

[0025] Figure 8 This is a diagram showing the operating status of each component in the dual active bridge DAB during the T3 to T4 operating phases.

[0026] Figure 9 This is a diagram showing the operating status of each component in the dual active bridge DAB during the T4 to T5 operating phases.

[0027] Figure 10 This is a diagram showing the operating status of each component in the dual active bridge DAB during the T5 to T6 operating phases. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are only used to explain this utility model and are not intended to limit this utility model.

[0029] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly or indirectly attached to that other component. When a component is referred to as being "connected to" another component, it can be directly or indirectly connected to that other component.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0031] Please see Figure 1 As shown, Figure 1 This is a structural diagram of an online battery capacity verification system based on a dual active bridge (DAB) according to an embodiment of this application. The online battery capacity verification system includes: multiple batteries under test, an electric switch, and multiple capacity verification devices; the multiple batteries under test are connected in series and then connected to a DC bus via the electric switch; each battery under test is connected in parallel to a capacity verification device, which is connected to the DC bus; wherein, the capacity verification devices perform charge-discharge capacity verification of the batteries under test based on a dual active bridge (DAB) structure.

[0032] Specifically, commercially available systems often use multiple batteries connected in series to a DC bus to power downstream equipment loads. The purpose of this application is to perform online charge-discharge capacity verification on these batteries. In the capacity verification system, multiple batteries are connected in series to a DC bus for power supply; an electric switch controls the connection of the batteries to the DC bus, opening during charge-discharge capacity verification testing and closing when the test ends; the capacity verification device is connected in parallel with a single battery, allowing for individual charge-discharge capacity verification of the battery.

[0033] The working logic of this application is as follows: During normal operation, the capacity accumulator is in standby mode, the electric switch is engaged, and multiple batteries are connected in series to the DC bus to supply power to the downstream equipment load through the electric switch. When capacity accumulator is required, the capacity accumulator operates, and the electric switch is disengaged to cut off the battery series circuit and switch to parallel operation mode. The capacity accumulator charges and discharges the battery cells for capacity accumulator. After the capacity accumulator is completed, the electric switch is engaged, the capacity accumulator is in standby mode, and switches back to series operation mode.

[0034] The improvement of this application lies in the addition of a capacity-capacitance device based on a dual active bridge (DAB) topology to the existing series-connected battery configuration. This capacity-capacitance device is then connected in parallel with the battery to perform parallel capacity-capacitance on a single battery cell, enabling online capacity-capacitance. This eliminates the need for complicated switching operations and allows for the designation of one or more batteries for individual capacity-capacitance without affecting the operation of the entire system. This significantly reduces the risk of load power failure associated with traditional capacity-capacitance and enables rapid detection of any abnormal conditions in a particular battery cell.

[0035] Please see Figure 2 As shown, Figure 2 This is a structural diagram of the capacity testing device provided in an embodiment of this application. As one possible implementation, the capacity testing device includes: a reverse connection protection circuit, a dual active bridge DAB, an auxiliary power supply circuit, a control circuit, a communication circuit, and a sampling circuit. One end of the reverse connection protection circuit is connected to the battery under test, and the other end is connected to the dual active bridge DAB. The dual active bridge DAB is connected to the DC bus. Both the DC bus and the battery under test are connected to the auxiliary power supply circuit. The auxiliary power supply circuit is connected to the control circuit. The control circuit is connected to the control terminal of the dual active bridge DAB. The control circuit is also connected to the communication circuit and the sampling circuit.

[0036] Specifically, in the capacity-integrated device, the reverse connection protection circuit is mainly used for reverse connection protection on the battery side. The dual active bridge DAB circuit mainly adopts the basic structure of the dual active bridge DAB topology. DAB is a dual active bridge inverter. Unlike the traditional DC operation mode, it mainly uses phase shift control, that is, by changing the lead-lag relationship between the primary and secondary sides, the energy flow is realized. The transmission power and output voltage can be controlled by controlling the duty cycle of the two AC square wave voltages Vab and Vcd and the phase difference between Vab and Vcd. Its working principle is: fix the inner phase shift angle and control the outer phase shift angle. If the output lags the input phase angle, it is forward transmission; if the input lags the output phase angle, it is reverse transmission, thereby realizing energy control during the battery charging and discharging capacity integration process. The auxiliary power circuit mainly supplies power through the battery or DC bus, and then supplies power to the control circuit. In the case of battery discharging capacity integration, the battery is used to supply power first, and the voltage is boosted to supply power to the control circuit. After the high voltage of the DC bus is established, the DC bus is used to supply power, and the voltage drops to supply power to the control circuit. The control circuit primarily generates waveforms to drive the power transistors of the dual active bridge DAB, thereby controlling the system's operating logic and achieving battery charging and discharging capacity verification. The sampling circuit and communication circuit are not improvements in this application and can directly utilize existing circuit modules; therefore, they will not be elaborated upon here.

[0037] The improvement of this application lies in the use of a capacity-enhancing device based on a dual active bridge (DAB) topology, which enables efficient and stable energy conversion between the high-voltage DC bus and the low-voltage battery under test. When the DC bus voltage phase leads the battery under test, energy flows from the DC bus to the battery under test, charging the battery and enhancing its capacity. When the battery under test voltage phase leads the DC bus, energy flows from the battery under test to the DC bus, discharging the battery and enhancing its capacity. This allows for isolated conversion between DC and DC power supplies, making it widely applicable to uninterrupted DC power supply for control equipment. Furthermore, the capacity-enhancing device can be configured with other related additional functions such as a BMS, charge / discharge management, and automatic switching.

[0038] Please see Figure 3 As shown, Figure 3 This is a structural diagram of a dual active bridge DAB provided in an embodiment of this application. The dual active bridge DAB includes: two full-bridge circuits, a high-frequency transformer, a high-voltage side filter capacitor, and a low-voltage side filter capacitor; the high-voltage side filter capacitor is connected to the first full-bridge circuit, the first full-bridge circuit is connected to one end of the high-frequency transformer, the other end of the high-frequency transformer is connected to the second full-bridge circuit, and the second full-bridge circuit is connected to the low-voltage side filter capacitor.

[0039] Furthermore, the high-voltage side filter capacitor is connected to the DC bus, and the low-voltage side filter capacitor is connected to the reverse connection protection circuit.

[0040] Furthermore, the full-bridge circuit is composed of four MOSFETs or IGBTs.

[0041] Furthermore, the full-bridge circuit is composed of four N-MOSFETs. For example... Figure 3 As shown, the full-bridge circuit is composed of four N-MOSFETs (such as S1, S2, S3, and S4).

[0042] Specifically, Figure 3 In the diagram, voltage V1 is the high-voltage side voltage (DC bus voltage), and voltage V2 is the low-voltage side voltage (battery voltage); Lr is the primary-side inductance, which also includes the primary-side leakage inductance; the transformer's magnetizing inductance is Lm; the high-voltage side filter capacitor is Cf1, and the low-voltage side filter capacitor is Cf2. The working principle of the dual active bridge (DAB) is as follows: a fixed inner phase shift angle is used, while the outer phase shift angle is controlled. If the output phase angle lags the input phase angle, it is forward transmission; if the input phase angle lags the output phase angle, it is reverse transmission.

[0043] It is understood that the capacity balancing device of this application adopts a high-efficiency dual active bridge (DAB) topology, which can meet the requirements of boosting and discharging the battery, stepping down to the battery voltage and charging the battery, and balancing individual cells.

[0044] The working principle of the dual active bridge DAB will now be introduced using forward operation as an example: Please refer to [link to relevant documentation]. Figure 4 As shown, Figure 4 This is a schematic diagram of the forward operating waveform of a dual active bridge DAB. In forward operating mode, energy is transferred from the DC source V1 to the V2 side, with vac1 leading vac2 by phase dT. VLr is defined as the voltage across inductor Lr, and iLr is the current flowing through the inductor. iLr > 0 represents the current flowing into the primary winding of the transformer. A complete switching cycle can be divided into 10 operating modes. The circuit components that do not participate in operation within each mode are drawn with dashed lines.

[0045] Stage 1 (t0-t1): Before time t1, the inductor current iLr < 0, and the current in the leading bridge flows through switches S2 and S3; the current in the lagging bridge flows through D6 and D7, and energy is transferred from power supply V1 to power supply V2, such as... Figure 5 As shown, Figure 5 This is a diagram showing the operating status of each component in the dual active bridge DAB during the T0 to T1 working phase.

[0046] Stage 2 (t1-t2): At time t1, parasitic capacitors C2 and C3 are charged, while parasitic capacitors C1 and C4 are discharged, thus enabling ZVS turn-off of switching transistors S2 and S3. At time t2, the drain-source voltages of S2 and S3 rise to V1, and the drain-source voltages of S1 and S4 decrease to 0, causing parasitic diodes D1 and D4 to conduct first. Figure 6 As shown, Figure 6 This is a diagram showing the operating status of each component in the dual active bridge DAB during the T1 to T2 operating phases.

[0047] Stage 3 (t2-t3): After D1 and D4 are turned on, switching transistors S1 and S4 achieve ZVS turn-on, as follows: Figure 7 As shown, Figure 7 This is a diagram showing the operating status of each component in the dual active bridge DAB during the T2 to T3 operating phases.

[0048] Stage 4 (t3-t4): Starting from time t3, the inductor current iLr > 0. The current in the leading bridge flows through switches S1 and S4; the current in the lagging bridge flows through switches S6 and S7. At this time, vLr = V1 + NV2, and iLr increases positively. In this mode, the voltage sources on both sides simultaneously store energy in the inductor, such as... Figure 8 As shown, Figure 8 This is a diagram showing the operating status of each component in the dual active bridge DAB during the T3 to T4 operating phases.

[0049] Stage 5 (t4-t5): At time t4, parasitic capacitors C6 and C7 are charged, while parasitic capacitors C5 and C8 are discharged, thus enabling ZVS turn-off of switching transistors S6 and S7. At time t5, the parasitic capacitances of power transistors S6 and S7 are charged to V2, and the parasitic capacitances of S5 and S8 are completely discharged, causing parasitic diodes D5 and D8 to conduct first. Figure 9 As shown, Figure 9 This is a diagram showing the operating status of each component in the dual active bridge DAB during the T4 to T5 operating phases.

[0050] Stage 6 (t5-t6): When D5 and D8 are turned on, switching transistors S5 and S8 achieve ZVS turn-on, as shown below. Figure 10 As shown, Figure 10 This is a diagram showing the operating status of each component in the dual active bridge DAB during the T5 to T6 operating phases.

[0051] Within the interval (t6-t10), the working condition of the converter in each mode can be analyzed similarly based on symmetry.

[0052] In one possible implementation, the nuclear capacity device has two states: standby or operation, and the state switching of the nuclear capacity device is determined by the state of the electric switching device.

[0053] Furthermore, when the electric switch is in the engaged state, the capacity verification device switches to standby mode; when the electric switch is in the disengaged state, the capacity verification device switches to operating mode. It is understood that the electric switch capacity verification device can cooperate with monitoring equipment, controlling the electric switch to engage or disengage based on capacity verification commands issued by the monitoring system, eliminating the need for manual operation and reducing the risk of misoperation. When capacity verification is required, the electric switch is disengaged, and the capacity verification device operates to perform charge and discharge capacity verification on individual battery cells; after verification is complete, the electric switch is engaged, and the capacity verification device enters standby mode.

[0054] In one possible implementation, the battery under test is a lead-acid battery, a lithium battery, or a sodium battery.

[0055] In one possible implementation, the battery under test uses 24 2V DC batteries with a DC bus of 48V DC. The online capacity verification system of this application can realize online automatic charge and discharge capacity verification of 2V to 48V batteries.

[0056] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A battery online capacity assessment system based on dual active bridge (DAB), characterized in that, include: Multiple batteries under test, electric switching device, and multiple capacity devices; Multiple batteries under test are connected in series and then connected to the DC bus via the electric switch device. Each battery under test is connected in parallel with a capacity device, which is connected to the DC bus. The capacity verification device is based on a dual active bridge (DAB) structure to perform charge-discharge capacity verification on the battery under test.

2. The battery online capacity assessment system based on dual active bridge (DAB) according to claim 1, characterized in that, The nuclear capacity device includes: a reverse connection protection circuit, a dual active bridge (DAB), an auxiliary power supply circuit, a control circuit, a communication circuit, and a sampling circuit; One end of the reverse connection protection circuit is used to connect to the battery under test, and the other end is connected to the dual active bridge DAB. The dual active bridge DAB is used to connect to the DC bus. Both the DC bus and the battery under test are connected to the auxiliary power circuit. The auxiliary power circuit is connected to the control circuit. The control circuit is connected to the control terminal of the dual active bridge DAB. The control circuit is also connected to the communication circuit and the sampling circuit.

3. The battery online capacity assessment system based on dual active bridge (DAB) according to claim 2, characterized in that, The dual active bridge (DAB) includes: two full-bridge circuits, a high-frequency transformer, a high-voltage side filter capacitor, and a low-voltage side filter capacitor; The high-voltage side filter capacitor is connected to the first full-bridge circuit, the first full-bridge circuit is connected to one end of the high-frequency transformer, the other end of the high-frequency transformer is connected to the second full-bridge circuit, and the second full-bridge circuit is connected to the low-voltage side filter capacitor.

4. The battery online capacity assessment system based on dual active bridge (DAB) according to claim 3, characterized in that, The high-voltage side filter capacitor is connected to the DC bus, and the low-voltage side filter capacitor is connected to the reverse connection protection circuit.

5. The battery online capacity assessment system based on dual active bridge (DAB) according to claim 3, characterized in that, The full-bridge circuit consists of four MOSFETs or IGBTs.

6. The battery online capacity assessment system based on dual active bridge (DAB) according to claim 5, characterized in that, The full-bridge circuit is composed of four N-MOSFETs.

7. The battery online capacity assessment system based on dual active bridge (DAB) according to claim 1, characterized in that, The nuclear capacity device has two states: standby and operation. The state switching of the nuclear capacity device is determined by the state of the electric switching device.

8. The battery online capacity assessment system based on dual active bridge (DAB) according to claim 7, characterized in that, When the electric switch is in the engaged state, the capacity storage device switches to standby state; when the electric switch is in the disengaged state, the capacity storage device switches to operating state.

9. The battery online capacity assessment system based on dual active bridge (DAB) according to claim 1, characterized in that, The battery under test is a lead-acid battery, a lithium battery, or a sodium battery.

10. The battery online capacity assessment system based on dual active bridge (DAB) according to claim 1, characterized in that, The battery under test consists of 24 2V dc batteries, and the DC bus is 48V dc.

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