Lithium battery pack parallel balance system

Abstract

The utility model relates to the technical field of batteries, and discloses a lithium battery pack parallel balance system which comprises a plurality of battery modules connected in parallel, and each battery module comprises a battery module and a structure formed by connecting a plurality of battery cells in series; the control module is connected with the output end of the battery module and is used for monitoring and managing the voltage and the residual capacity of the battery module; and the DC-DC boosting module is connected with the output end of the control module and is used for balancing the residual capacity of the plurality of battery modules which are connected in parallel. The control module and the DC-DC boosting module are combined and designed in the battery module, so that detection of battery voltage, logic judgment and balance protection and charge-discharge management of a power supply are realized, the load driving power requirement is met, the battery voltage and the residual capacity of the battery packs connected in parallel are completely consistent, and the power supply efficiency is improved. The response speed and the working efficiency of the system are effectively improved, and the stability of the overall performance of the battery pack is ensured.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and particularly relates to a lithium battery pack parallel balancing system. BACKGROUND

[0002] In today's energy application field, lithium batteries are widely used in various devices due to their high energy density, long cycle life and many other advantages. In the actual use scene of many lithium battery systems, when the demand of the load for electric energy exceeds the power supply capacity of a single battery pack, that is, a larger amount of electric energy is needed to drive the load, the power supply mode of multiple battery packs in parallel becomes a common choice.

[0003] However, this application of multiple battery packs in parallel faces severe challenges. In actual situations, there will inevitably be a situation of uneven voltage between battery packs. Once this situation occurs, during parallel discharging, according to the principle of circuit, the lithium battery group with high voltage will cause the discharging current to increase significantly due to the larger voltage difference between it and the load; while the lithium battery group with low voltage will cause the discharging current to decrease accordingly due to the smaller voltage difference. It should be noted that the use conditions of lithium batteries are extremely harsh, and their working state is extremely sensitive to changes in parameters such as voltage and current, and a slight mistake can easily cause a safety accident.

[0004] Therefore, in order to enable lithium battery packs to work normally, a current limiting circuit is usually added in the circuit. However, this conventional solution has obvious drawbacks. On the one hand, the traditional current limiting module takes a long time to execute the operation of balancing the battery packs in parallel, which greatly affects the response speed and working efficiency of the system. On the other hand, when the electric quantity between the battery groups gradually approaches, the mutual charging current in the balancing process will decrease sharply, and even be too small to effectively balance the battery groups, thereby causing a large error in the remaining capacity (SOC) of the battery packs and seriously affecting the stability and consistency of the overall performance of the battery groups. CONTENT OF THE UTILITY MODEL

[0005] In order to solve the deficiencies of the prior art, the application provides a lithium battery pack parallel balancing system, which combines a control module and a DC-DC boost module in a battery module to realize detection of battery voltage, logical judgment, balancing protection of power supply, and charging and discharging management, so as to meet the power demand of the load while the battery voltages of multiple parallel battery groups and the remaining capacity of the battery groups are completely consistent, thereby effectively improving the response speed and working efficiency of the system and ensuring the stability of the overall performance of the battery groups.

[0006] The technical effects achieved by the application are realized through the following aspects:

[0007] The application provides a lithium battery pack parallel balancing system, which comprises multiple parallel battery modules, and each battery module comprises:

[0008] a battery module, a structure composed of a plurality of battery cells connected in series;

[0009] a control module, connected to an output end of the battery module, for monitoring and managing voltage and remaining capacity of the battery module; and

[0010] a DC-DC boost module, connected to an output end of the control module, for balancing the remaining capacity of a plurality of the battery modules connected in parallel.

[0011] In some implementations, the DC-DC boost module comprises:

[0012] a power input module, connected to the control module, for providing raw direct current power;

[0013] a full-bridge inverter module, connected to an output end of the power input module, for inverting the input direct current into high-frequency alternating current;

[0014] a transformer and filter module, connected to an output end of the full-bridge inverter module;

[0015] a full-bridge rectifier module, connected to an output end of the transformer and filter module; and

[0016] an output module, connected to an output end of the full-bridge rectifier module.

[0017] In some implementations, the power input module comprises a capacitor C_p1 connected in parallel with the battery module.

[0018] In some implementations, the full-bridge inverter module comprises a transistor Q1 and a transistor Q2 connected in series and a transistor Q3 and a transistor Q4 connected in series; the transistor Q1 and the transistor Q2 are arranged in parallel with the transistor Q3 and the transistor Q4 connected in series.

[0019] In some implementations, a drain of the transistor Q1 is connected to a positive electrode of the battery module, a source of the transistor Q1 is connected to a drain of the transistor Q2, and a source of the transistor Q2 is connected to ground.

[0020] A drain of the transistor Q3 is connected to the positive electrode of the battery module, a source of the transistor Q3 is connected to a drain of the transistor Q4, and a source of the transistor Q4 is connected to ground.

[0021] In some implementations, the transformer and filter module comprises a transformer T1, an inductor L1, and a capacitor C1.

[0022] A primary winding of the transformer T1 is connected to the full-bridge inverter module.

[0023] The secondary winding output end of the transformer T1 is connected with one end of the inductor L1, the other end of the inductor L1 is connected with one end of the capacitor C1, the other end of the capacitor C1 is grounded, and the input end of the full-bridge rectification module is connected.

[0024] In some implementations, the full-bridge rectification module includes transistors Q5 and Q6 in series and transistors Q7 and Q8 in series; and the transistors Q5 and Q6 are arranged in parallel with the transistors Q7 and Q8 in series.

[0025] In some implementations, the drain of the transistor Q5 and the drain of the transistor Q7 are both connected with the output end of the transformer and filter module;

[0026] The source of the transistor Q5 is connected with the drain of the transistor Q6, and the source of the transistor Q6 is grounded;

[0027] The source of the transistor Q7 is connected with the drain of the transistor Q8, and the source of the transistor Q8 is grounded.

[0028] In some implementations, the output module includes a capacitor C3 and an intermediate bus Mi dbus, one end of the capacitor C3 is connected with the intermediate bus Mi dbus, and the other end of the capacitor C3 is grounded.

[0029] In some implementations, the control module includes an MCU unit and a BMS unit connected with each other.

[0030] In summary, the present application has at least the following advantages:

[0031] The lithium battery pack parallel balancing system provided by the present application can monitor the voltage of the input end and the output end of the battery pack and the residual capacity of the battery cell group by using the combined design of the control module and the DC-DC boost module; when an error is detected, the charging and discharging balancing is performed, which can eliminate the problem of large residual capacity error of the battery pack while meeting the power demand of the load driving, thereby ensuring that the voltage platforms of the battery modules are more balanced and the residual capacity consistency is better.

[0032] When the parallel balancing of multiple lithium battery groups is completed and the voltages and residual capacities of the battery groups are consistent, the discharging is allowed to be performed at the same time, thereby effectively ensuring the stability and consistency of the overall performance of the battery groups.

[0033] In addition, the method can perform the parallel balancing of the battery pack in a short time, thereby effectively improving the response speed and working efficiency of the system. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1The figure is a structural schematic diagram of the lithium battery pack parallel balancing system in Embodiment 1 of the present application.

[0035] Figure 2 The figure is a structural schematic diagram of the battery module in Embodiment 1 of the present application.

[0036] Figure 3 The figure is a structural schematic diagram of the control module in Embodiment 1 of the present application.

[0037] Figure 4 The figure is a structural schematic diagram of the DC-DC voltage boosting module in Embodiment 2 of the present application.

[0038] Figure 5 The figure is a structural schematic diagram of the electric vehicle in Embodiment 3 of the present application.

[0039] Markings in the figure:

[0040] 1, battery module, 11, battery module, 12, control module, 121, MCU unit, 122, BMS unit, 13, DC-DC voltage boosting module, 131, power input module, 132, full-bridge inverter module, 133, voltage transformation and filtering module, 134, full-bridge rectifier module, 135, output module;

[0041] 100, lithium battery pack parallel balancing system; 200, electric vehicle. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme 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. The described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application.

[0043] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts, fall within the scope of protection of the present application.

[0044] Embodiment 1:

[0045] Please refer to the drawings Figure 1 - the drawings Figure 3 The lithium battery pack parallel balancing system of the present application includes a plurality of parallel battery modules 1, and each battery module 1 includes a battery module 11, a control module 12 and a DC-DC voltage boosting module 13. Specifically, the battery module 1 adopts a wire harness parallel structure to connect the plurality of battery modules 1 in parallel.

[0046] The battery module 11 is composed of a structure of a plurality of battery cells connected in series. Preferably, it is composed of 16 battery cells connected in series.

[0047] The control module 12 is connected with the output end of the battery module 11, and is used for monitoring and managing the voltage and residual capacity of the battery module 1. Specifically, the control module 12 comprises an MCU unit 121 and a BMS unit 122 connected with each other. The MCU unit 121 precisely controls the switching tube, controls the rhythm of the switching tube inverting and rectifying, and realizes efficient conversion of electric energy. By monitoring the voltage, current and other parameters in real time, the output is dynamically adjusted to ensure voltage stability. Once the circuit has overcurrent, overtemperature and other abnormalities, the protection mechanism is started quickly to ensure the safe and stable operation of the circuit. The BMS unit 122 is mainly responsible for the comprehensive management of the battery, and precisely monitors the voltage, residual capacity, current, temperature and other parameters of the battery to determine the state of the battery. The BMS can also prevent overcharging and overdischarging of the battery, balance the power of each battery in the battery pack, prolong the service life of the battery and ensure the safety of the system.

[0048] The DC-DC boost module 13 is connected with the output end of the control module 12, and is used for balancing the residual capacity of a plurality of parallel-connected battery modules 1. Specifically, the DC-DC boost module 13 is mainly used for boosting the direct current voltage. It can convert the lower input direct current voltage and residual capacity into higher direct current output voltage and residual capacity until the voltage of the battery pack and the residual capacity of the battery pack reach a balanced state.

[0049] The lithium battery pack parallel balancing system 100 in the embodiment can monitor the voltage of the input end and the output end of the battery pack and the residual capacity of the battery cell group by using the combined design of the control module 12 and the DC-DC boost module 13. When an error is detected, the DC-DC boost module 13 can quickly charge the battery pack with low voltage, and the maximum current can reach 15A until the voltage of the battery pack is consistent, thereby realizing charge and discharge balancing. While meeting the power demand of the load driving, the problem of large residual capacity error of the battery pack can be eliminated, thereby ensuring that the voltage platform of the battery module 1 is more balanced and the consistency of the residual capacity is better. When a plurality of lithium battery packs are balanced, the battery pack voltage and the residual capacity are consistent, and the discharge can be performed at the same time, thereby effectively ensuring the stability and consistency of the overall performance of the battery pack.

[0050] In this structure, the method is used to perform the operation of balancing the parallel battery pack, which takes a short time and can effectively improve the response speed and working efficiency of the system.

[0051] Embodiment 2:

[0052] The difference between this embodiment and embodiment 1 is that, please refer to Figure 4The DC-DC voltage boosting module 13 of the embodiment comprises a power input module 131, a full-bridge inverter module 132, a voltage transformation and filtering module 133, a full-bridge rectifier module 134, and an output module 135.

[0053] The power input module 131 is connected with the control module 12 at the input end, and is configured to provide original direct current power. Specifically, the power input module 131 comprises a capacitor C_p1 connected in parallel with the battery module 11. The power input module 131 provides original direct current power, and the capacitor C_p1 is configured to absorb the spike voltage generated in the process of transistor switching, thereby effectively protecting the circuit.

[0054] The full-bridge inverter module 132 is connected with the output end of the power input module 131, and is configured to invert the input direct current into high-frequency alternating current. Specifically, the full-bridge inverter module 132 comprises transistors Q1 and Q2 connected in series, and transistors Q3 and Q4 connected in series; the transistors Q1 and Q2 are connected in parallel with the transistors Q3 and Q4 connected in series.

[0055] The drain electrode of the transistor Q1 is connected with the positive electrode of the battery module 11, and the source electrode of the transistor Q1 is connected with the drain electrode of the transistor Q2; the source electrode of the transistor Q2 is connected with the ground; the drain electrode of the transistor Q3 is connected with the positive electrode of the battery module 11, and the source electrode of the transistor Q3 is connected with the drain electrode of the transistor Q4; and the source electrode of the transistor Q4 is connected with the ground.

[0056] It should be noted that, in the process of circuit operation, the control signals sent by the MCU unit 121 are configured to alternately control the transistors Q1 and Q4 to be turned on at the same time, the transistors Q2 and Q3 to be turned off at the same time, and the transistors Q2 and Q3 to be turned on at the same time, and the transistors Q1 and Q4 to be turned off. For example, when the transistors Q1 and Q4 are turned on, the current flows out from the positive electrode of the battery, passes through the transistor Q1, flows through the primary winding of the transformer T1, and finally returns to the negative electrode of the battery through the transistor Q4, thereby forming a current in one direction on the primary winding of the transformer; when the transistors Q2 and Q3 are turned on, the current flows out from the positive electrode of the battery, passes through the transistor Q3, flows through the primary winding of the transformer T1, and finally returns to the negative electrode of the battery through the transistor Q2, thereby forming a current in the opposite direction on the primary winding of the transformer. In this way, the direct current is inverted into high-frequency alternating current, thereby providing a suitable input signal for the voltage transformation and filtering module 133.

[0057] The transformer T1, the inductor L1 and the capacitor C1 are included in the voltage transformation and filtering module 133. The primary winding of the transformer T1 is connected with the full-bridge inverter module 132. The secondary winding of the transformer T1 is connected with one end of the inductor L1. The other end of the inductor L1 is connected with one end of the capacitor C1. The other end of the capacitor C1 is grounded. The input end of the full-bridge rectifier module 134 is connected.

[0058] In this connection mode, the transformer T1 transforms the high-frequency alternating current output by the full-bridge inverter module 132 according to the ratio of the primary winding and the secondary winding. The high-frequency alternating current transformed by the transformer T1 flows into the inductor L1. Since the inductor has the characteristic of inhibiting current mutation, it can hinder the rapidly changing current component in the high-frequency alternating current. Then, the current flows into the capacitor C1. The capacitor C1 presents low impedance to the high-frequency alternating current, and bypasses the high-frequency noise remaining after the preliminary processing of the inductor L1 to the ground, thereby outputting relatively smooth high-frequency alternating current to the full-bridge rectification and output module 135, completing the function of voltage transformation and filtering, and laying a foundation for subsequent rectification and stable DC output.

[0059] The full-bridge rectifier module 134 is connected with the output end of the voltage transformation and filtering module 133. Specifically, the full-bridge rectifier module 134 includes the transistors Q5 and Q6 connected in series and the transistors Q7 and Q8 connected in series. The transistors Q5 and Q6 are connected in parallel with the transistors Q7 and Q8 connected in series.

[0060] The drain of the transistor Q5 and the drain of the transistor Q7 are connected with the output end of the voltage transformation and filtering module 133. The source of the transistor Q5 is connected with the drain of the transistor Q6. The source of the transistor Q6 is grounded. The source of the transistor Q7 is connected with the drain of the transistor Q8. The source of the transistor Q8 is grounded.

[0061] The output module 135 is connected with the output end of the full-bridge rectifier module 134. Specifically, the output module 135 includes the capacitor C3 and the intermediate bus Mi dbus. One end of the capacitor C3 is connected with the intermediate bus Mi dbus. The other end of the capacitor C3 is grounded.

[0062] During operation, the high-frequency AC power input from the transformer and filter module 133 is rectified into DC power in the positive half-cycle. The control signal turns on transistors Q5 and Q8, while transistors Q6 and Q7 are turned off. Current flows from the output of the transformer and filter module 133 through transistor Q5, the load (connected to the intermediate bus idbus), and back to ground via transistor Q8. In the negative half-cycle, the control signal turns on transistors Q6 and Q7, while transistors Q5 and Q8 are turned off. Current then flows from the output of the transformer and filter module 133 through transistor Q7, the load, and back to ground via transistor Q6. This process rectifies the high-frequency AC power into DC power, which is then further filtered by capacitor C3 to eliminate ripple in the DC voltage. Finally, a stable DC voltage is output to the intermediate bus idbus, providing a stable power supply for subsequent electrical equipment.

[0063] In this embodiment, the DC-DC boost module 13 integrates multiple sub-modules and plays a crucial role. Among them, the power input module 131 provides initial DC power. The full-bridge inverter module 132 inverts the DC power into high-frequency AC power for subsequent processing. The transformer and filter module 133 performs voltage transformation and filtering on the high-frequency AC power, preparing it for boosting.

[0064] The DC-DC boost module 13 further boosts the voltage of the pre-processed electrical energy according to circuit requirements. Through a specific control strategy, the various sub-modules work together to raise the relatively low input voltage to a higher level. The full-bridge rectifier module 134 then converts the boosted high-frequency AC power into DC power, which is finally output as stable high-voltage DC power by the output module 135. This achieves bidirectional energy conversion, enabling the battery pack to boost from 42-58V DC to 60V DC via Midbus and supply power to other battery packs for balancing. This efficient parallel balancing of the battery packs ensures consistent voltage and remaining capacity in the parallel-connected battery packs, resulting in a longer and safer overall battery pack lifespan. Furthermore, the entire process effectively meets the requirements of devices or modules requiring high-voltage power supply, ensuring their normal operation.

[0065] Example 3:

[0066] This embodiment is based on the above embodiment; please refer to [link / reference]. Figure 5 An electric vehicle 200 is provided, including the aforementioned lithium battery pack parallel balancing system 100.

[0067] The electric vehicle 200 in the embodiment can adjust the power difference between the battery monomers by the parallel balancing system 100, avoid overcharging or over-discharging of some batteries, slow down the aging speed of the batteries, prolong the service life of the entire battery pack, and reduce the cost of replacing the batteries.

[0068] In addition, by balancing the power of each battery module 11, the overall performance of the battery module 11 is more stable, the output voltage is more stable, and the energy waste caused by unbalanced batteries can be effectively reduced. Through the setting, the battery module 11 can release more effective electric energy, thereby improving the endurance mileage of the electric vehicle 200 and reducing the mileage anxiety of the user.

[0069] At the same time, it can also avoid safety problems such as thermal runaway caused by overcharging or over-discharging of the battery, improve safety, and when the parallel balancing battery pack is executed by using the method, the operation time is short, the response speed and working efficiency of the system can be effectively improved, thereby improving the overall charging efficiency, shortening the charging time, and improving the user experience.

[0070] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0071] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly used when the product of the application is used, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application. In addition, the terms "first", "second", "third" and the like are only used for differentiation and cannot be understood as indicating or implying relative importance.

[0072] In addition, the terms "horizontal", "vertical", "suspension" and the like do not mean that the components must be absolutely horizontal or suspended, but can be slightly inclined. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0073] In this application, unless otherwise explicitly specified and limited, a first feature on or under a second feature can include the first and second features being in direct contact, or can include the first and second features not being in direct contact but being in contact through another feature therebetween. Also, a first feature on, above and over a second feature includes the first feature being directly above and obliquely above the second feature, or simply means the first feature being horizontally higher than the second feature. A first feature under, below and under a second feature includes the first feature being directly below and obliquely below the second feature, or simply means the first feature being horizontally lower than the second feature.

[0074] Although the present application has been described in connection with the preferred embodiments thereof with reference to the drawings, it will be apparent to those skilled in the art that many changes, modifications, variations and substitutions can be made therein without departing from the spirit and scope of the application. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and scope of the appended claims.

Claims

1. A lithium battery pack parallel balancing system, characterized in that, The battery module is composed of a plurality of battery cells connected in series. The battery module is composed of a plurality of battery cells connected in series. The control module is connected to the output end of the battery module and is used for monitoring and managing the voltage and residual capacity of the battery module. The DC-DC boost module is connected to the output end of the control module and is used for balancing the residual capacity of the plurality of parallel battery modules.

2. The lithium battery pack parallel balancing system of claim 1, wherein, The DC-DC boost module includes: The power input module is connected to the control module and is used for providing raw DC power. The full-bridge inverter module is connected to the output end of the power input module and is used for inverting the input DC power into high-frequency AC power. The transformer and filter module is connected to the output end of the full-bridge inverter module. The full-bridge rectifier module is connected to the output end of the transformer and filter module. The output module is connected to the output end of the full-bridge rectifier module.

3. The lithium battery pack parallel balancing system of claim 2, wherein, The power input module includes a capacitor C_p1 connected in parallel with the battery module.

4. The lithium battery pack parallel balancing system of claim 2, wherein, The full-bridge inverter module includes transistors Q1 and Q2 connected in series and transistors Q3 and Q4 connected in series; the transistors Q1 and Q2 are connected in parallel with the transistors Q3 and Q4.

5. The lithium battery pack parallel balancing system of claim 4, wherein, The drain of the transistor Q1 is connected to the positive electrode of the battery module, and the source of the transistor Q1 is connected to the drain of the transistor Q2; the source of the transistor Q2 is grounded. The drain of the transistor Q3 is connected to the positive electrode of the battery module, and the source of the transistor Q3 is connected to the drain of the transistor Q4; the source of the transistor Q4 is grounded.

6. The lithium battery pack parallel balancing system of claim 2, wherein, The transformer and filter module includes a transformer T1, an inductor L1, and a capacitor C1. The primary winding of the transformer T1 is connected to the full-bridge inverter module. The secondary winding output end of the transformer T1 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to one end of the capacitor C1, the other end of the capacitor C1 is grounded, and the input end of the full-bridge rectifier module is connected.

7. The lithium battery pack parallel balancing system of claim 2, wherein, The full-bridge rectifier module includes transistors Q5 and Q6 connected in series and transistors Q7 and Q8 connected in series; and the transistors Q5 and Q6 are connected in parallel with the transistors Q7 and Q8.

8. The lithium battery pack parallel balancing system of claim 7, wherein, The drain of the transistor Q5 and the drain of the transistor Q7 are both connected to the output end of the transformer and filter module. The source of the transistor Q5 is connected to the drain of the transistor Q6, and the source of the transistor Q6 is grounded. The source of the transistor Q7 is connected to the drain of the transistor Q8, and the source of the transistor Q8 is grounded.

9. The lithium battery pack parallel balancing system of claim 2, wherein, The output module includes a capacitor C3 and a middle bus Midbus, one end of the capacitor C3 is connected to the middle bus Midbus, and the other end of the capacitor C3 is grounded.

10. The lithium battery pack parallel balancing system of claim 1, wherein, The control module includes an MCU unit and a BMS unit connected in series.

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