CN117734525A - Battery charging capacity balancing system for electric automobile - Google Patents
Battery charging capacity balancing system for electric automobile Download PDFInfo
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- CN117734525A CN117734525A CN202311181205.XA CN202311181205A CN117734525A CN 117734525 A CN117734525 A CN 117734525A CN 202311181205 A CN202311181205 A CN 202311181205A CN 117734525 A CN117734525 A CN 117734525A
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- equalization
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- 230000008901 benefit Effects 0.000 abstract description 7
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 4
- 229910052744 lithium Inorganic materials 0.000 abstract description 4
- 238000001514 detection method Methods 0.000 description 14
- 238000000034 method Methods 0.000 description 13
- 230000008569 process Effects 0.000 description 5
- 238000013459 approach Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
Abstract
The invention belongs to the technical field of batteries of electric vehicles, and particularly relates to a battery charging capacity balancing system of an electric vehicle, which comprises the following components: the battery cell module comprises 128 battery cells connected in series; the parallel package module is provided with two groups, each group of parallel package module comprises two groups of parallel packages, and each group of parallel packages comprises 8 electric cores; the equalization circuit module comprises a passive equalization module and an active equalization module; and the stack module comprises two groups of parallel branches, and the parallel branches are formed by equalization circuit modules connected in series. According to the invention, through arranging the battery core module, the parallel package module, the equalization circuit module and the stack module, the advantages of passive equalization and active equalization are combined, so that the equalization level of the autonomous battery owned by the battery package in the whole driving period is measured, and the equalization can be realized rapidly in order to solve the problem of inconsistent battery core capacity of the lithium battery more effectively.
Description
Technical Field
The invention belongs to the technical field of batteries of electric vehicles, and particularly relates to a battery charging capacity balancing system of an electric vehicle.
Background
Battery Management Systems (BMS) are critical to battery management processes for Electric Vehicles (EVs) and Hybrid Electric Vehicles (HEVs). The BMS is responsible for supervising against system damage, estimating the remaining life of the batteries, and ensuring that they continue to operate effectively and reliably. The BMS uses hardware and software to adjust these variables while monitoring the voltage, current and temperature of the battery, and its SOC and state of health (SOH).
BMS has a variety of uses, the most important of which is to ensure that the cell capacities are all at the same level. Cell capacity imbalance is a major factor in reducing battery life and overall battery capacity over time when the battery is used. Cell capacity imbalance is mainly caused by internal and environmental influences. The internal source is caused by the manner in which the cells are manufactured, which causes the internal impedance and storage capacity of each cell to be different. The thermal temperature and excessive charge-discharge cycles can cause external effects. Unbalanced batteries can create various electrical problems, including Overcharge (OC) and Overdischarge (OD) failures.
Overcharge occurs when a voltage greater than a high threshold of the battery is applied to the battery during charging
(OC). Such failure will cause the cell to heat up very rapidly and accelerate the solid electrolyte interface process (SEI). Therefore, thermal Runaway (TR) and internal short circuit may occur. On the other hand, if the discharge of the battery is below the low threshold voltage, overdischarge (OD) may be found. The copper electrode oxidizes due to over-discharge (OD) and passes from the anode to the cathode through the separator. The separator may be penetrated by this process, and an internal short circuit of the battery may occur. Overdischarge (OD) increases the internal resistance of the battery and decreases the capacity of the battery. Because of this, the BMS plays a very important role in preventing Overcharge (OC) and Overdischarge (OD) faults and slowing down the degradation occurrence speed of the battery capacity.
Currently, there are two main strategies, passive Equalization (PE) and Active Equalization (AE), for preventing OC or OD failures and equalizing the voltage between the batteries. The PE method involves releasing the stored energy of the cell with the higher voltage until the voltage of the lowest voltage cell is reached. The AE method moves energy from one cell to another. The transferred energy value is reduced because the assembly of the battery and the cell does not meet the ideal standard. This value is smaller compared to the PE method. Thus, this Active Equalization (AE) approach is more efficient than the passive approach (PE). On the other hand, PE results in longer equalization time and lower energy conversion efficiency than AE.
The structural benefit of PE is that it is easy to implement in hardware, but this solution results in significant energy loss due to heat dissipation. On the other hand, the AE structure has little energy loss, but the implementation of such a structure encounters a lot of difficulties, for example, although the equalization type using the capacitor is easy to construct and low in cost, they have a disadvantage in that surge current which may damage the battery cells is generated.
Disclosure of Invention
The invention aims to provide an electric automobile battery charging capacity balancing system which aims to solve the problems in the prior art in the background art.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention provides an electric automobile battery charging capacity balancing system, which comprises: the battery cell module comprises 128 battery cells connected in series; the parallel package module is provided with two groups, each group of parallel package module comprises two groups of parallel packages, and each group of parallel packages comprises 8 electric cores; the equalization circuit module comprises a passive equalization module and an active equalization module; and the stack module comprises two groups of parallel branches, and the parallel branches are formed by equalization circuit modules connected in series.
Preferably, the active equalization module includes multiple groups of inductors.
Preferably, the passive equalization module includes a resistor for dissipating energy.
Preferably, different SOC values are provided in part of the cells.
Preferably, the parallel packet module and the stack module comprise completely independent passive equalization and active equalization topologies.
Preferably, the parallel packet module and the stack module both comprise a topology structure combining passive equalization and active equalization.
Preferably, the stack module and the parallel package module are connected with the battery pack.
The invention has the technical effects and advantages that: compared with the prior art, the battery charging capacity balancing system for the electric automobile has the following advantages:
according to the invention, through arranging the battery core module, the parallel package module, the equalization circuit module and the stack module, the advantages of passive equalization and active equalization are combined, so that the equalization level of the autonomous battery owned by the battery package in the whole driving period is measured, and the equalization can be realized rapidly in order to solve the problem of inconsistent battery core capacity of the lithium battery more effectively.
Drawings
Fig. 1 is a schematic diagram of a topology structure of a battery charging capacity balancing system of an electric vehicle according to an embodiment of the present invention;
FIG. 2 is a graph showing the comparison result of different equalization techniques according to an embodiment of the present invention;
fig. 3 is a schematic diagram of SOC percentages of a topological SL in an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. The specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Batteries in electric vehicles are managed by a system called a BMS. The voltage, current and temperature readings of the battery pack are used to control several core parameters to ensure that it continues to function properly. Balancing the voltages of all the cells in a battery is one of the most important things to extend its life. Another important factor is maintaining an appropriate charge level to ensure that the electric vehicle has sufficient range. Passive Equalization (PE) and Active Equalization (AE) are two main approaches to cell equalization.
The advantage in this embodiment is that the advantages of both methods are being combined to measure the level of autonomous battery equalization that the battery pack possesses throughout the driving cycle. In order to more effectively solve the problem of inconsistent battery cell capacity of the lithium battery, a topological structure of Hybrid Equalization (HE) of the battery cell of the lithium battery and a working principle thereof are provided. Specifically, the following is described.
As shown in fig. 1, fig. 1 is a schematic topology diagram of an electric vehicle battery charging capability balancing system according to an embodiment of the present invention.
The embodiment of the invention provides an electric automobile battery charging capacity balancing system.
Exemplary, it includes: the device comprises a battery core module, a parallel package module, an equalization circuit module and a stack module.
Wherein the battery cell module comprises 128 battery cells connected in series; the parallel package modules are provided with two groups, each group of parallel package modules comprises two groups of parallel packages, and each group of parallel packages comprises 8 electric cores; the equalization circuit module comprises a passive equalization module and an active equalization module; the stack module comprises two groups of parallel branches, and the parallel branches are formed by equalization circuit modules connected in series.
The purpose of this is to propose a Hybrid Equalization (HE) concept to equalize the voltage differences existing between the stack and the modules at the same time. A resistor dissipating energy is used in the PE section, while a number of inductors are used in the AE section. For this purpose, 128 cells are integrated into a series package.
Specifically, the series of systems consisted of 2 groups of 8 stacks each, each stack consisting of 8 cells. The entire system consisted of 2 parallel branches consisting of a series system, the battery packs outputting a total of 94.72 kilowatt-hours capacity. Some of the cells are equipped with different SOC values so that voltage imbalance conditions can be simulated. To correct the voltage values and compare the equalization time and SOC levels, completely independent PE and AE topologies, and combinations of both techniques, are used at both stack and module level.
Illustratively, fig. 1 depicts this HE topology. The battery proposed in this patent has 128 cells connected in series. The battery voltage was 473.6V and the individual cell voltage was rated at 3.7V. The stack of modules is divided into 8 different groups. Each stack on (level 1) has eight cells connected in series.
As shown in fig. 2 and 3, which compare several equalization strategies compared in terms of equalization time, cell-SOC, and stack-SOC percentages. The SOC of the hybrid active-passive equalization method between stack and component was 96.20% lower than that of the pure AE method by 1.80%. Second, using ae+ at CL and mixed PE at stack exhibited 84.80% SOC and considerable response time compared to the AE-only approach. The AE topology of the system contains more electrical components than the PE topology, which requires more real space in the battery pack.
From the above, preliminary results show that the topology described in this patent is very efficient and can be balanced quickly. HE schemes are faster in cell equalization than PE and AE strategies. At the same time, this arrangement allows for cross-layer energy exchange, although increasing the number of switches increases switching losses and control complexity.
In some other embodiments, the passive equalization strategy includes: respectively carrying out voltage detection and temperature detection on each battery in a battery pack in the BMS; judging the state of the battery pack according to the detection result of each battery, and carrying out charge and discharge management on the BMS battery pack according to the judgment result; the management of the battery pack is carried out, whether the BMS battery pack is in an equilibrium state or not is monitored in real time, and the battery pack in an unbalanced state is connected into a passive equilibrium path; the PTC releases the redundant electric quantity in the battery to transfer energy, so that the voltage and the temperature of each battery become balanced, and the BMS battery pack reaches an balanced state.
When the battery pack is charged or discharged, detecting the voltage of each battery in the battery pack, detecting the voltage change of the battery pack, and recording the voltage change; when the battery pack is charged or discharged, the temperature of each battery cell in the battery pack is detected, a temperature threshold is set, and whether the temperature of the battery cell in the battery pack is in a normal temperature threshold range is judged. Detecting the voltage, the temperature and the battery SOC of the battery pack to obtain the current real-time state and the detection result of the battery pack; analyzing and judging the detection result, and checking whether the battery pack is in an equilibrium state or not; and accessing the battery pack in an unbalanced state into a passive equalization path. Charging or discharging the battery pack connected into the passive equalization path, and monitoring the temperature of the battery in the battery pack in real time; in the process of charging and discharging the battery, transferring energy of redundant electric quantity generated in the process of charging the battery; and respectively balancing the voltage and the temperature of each battery in the battery pack to obtain the balanced battery pack.
In still other embodiments, the active equalization strategy includes: each single battery in the battery pack is connected in parallel with a single battery detection equalizing charge module, and the single battery detection equalizing charge modules work independently; the single-battery detection equalization module comprises a single-battery detection unit and an equalization charging unit; the single battery detection unit is used for detecting parameters of the single battery and calculating the charge state of the single battery; the equalizing charge unit converts the energy of the battery pack into low-voltage output to charge the single battery in a low-charge state; the equalizing charge is that the battery pack charges a single battery through a DC/DC converter; comparing the charge states of the single batteries with the average charge state of the battery pack; the comparison of the charge states is realized through the whole vehicle controller, and the whole vehicle controller sends out an instruction to control the single cell detection equalization module to work; the vehicle controller and each single battery detection equalization module adopt isolated CAN buses to exchange information; when the charge state of the single battery is lower than the average charge state of the battery pack, the single battery detection equalizing charge module starts equalizing charge on the single battery; the energy used for equalizing charge is derived from the battery pack; when the charge state of the single battery is close to the average charge state threshold of the battery pack, the single battery detection equalizing charge module closes equalizing charge of the single battery; when all the single batteries which are started to be charged in an equalizing manner are charged, the equalizing charging of the whole battery pack is finished, and the charge states of all the batteries are basically consistent; repeating the steps, and performing a new cycle; when the state of charge of each cell in the battery is close to the average state of charge of the battery, no charge equalization is required.
Finally, it should be noted that: the foregoing description is only illustrative of the preferred embodiments of the present invention, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described, or equivalents may be substituted for elements thereof, and any modifications, equivalents, improvements or changes may be made without departing from the spirit and principles of the present invention.
Claims (7)
1. An electric vehicle battery charge capacity equalization system, comprising:
the battery cell module comprises 128 battery cells connected in series;
the parallel package module is provided with two groups, each group of parallel package module comprises two groups of parallel packages, and each group of parallel packages comprises 8 electric cores;
the equalization circuit module comprises a passive equalization module and an active equalization module;
and the stack module comprises two groups of parallel branches, and the parallel branches are formed by equalization circuit modules connected in series.
2. The battery charge capacity equalization system of claim 1, wherein said active equalization module comprises a plurality of groups of inductors.
3. The battery charge capacity equalization system of an electric vehicle of claim 2, wherein: the passive equalization module includes a resistor therein that dissipates energy.
4. The battery charge capacity equalization system of an electric vehicle of claim 1, wherein: different SOC values are provided in part of the cells.
5. The battery charge capacity equalization system of an electric vehicle of claim 1, wherein: and the parallel package module and the stack module comprise completely independent passive equalization topological structures and active equalization topological structures.
6. The battery charge capacity equalization system of an electric vehicle of claim 1, wherein: the parallel package module and the stack module comprise topological structures combining passive equalization and active equalization.
7. The battery charge capacity equalization system of an electric vehicle of claim 1, wherein: the stack module and the parallel package module are connected with the battery pack.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311181205.XA CN117734525A (en) | 2023-09-14 | 2023-09-14 | Battery charging capacity balancing system for electric automobile |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311181205.XA CN117734525A (en) | 2023-09-14 | 2023-09-14 | Battery charging capacity balancing system for electric automobile |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117734525A true CN117734525A (en) | 2024-03-22 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202311181205.XA Pending CN117734525A (en) | 2023-09-14 | 2023-09-14 | Battery charging capacity balancing system for electric automobile |
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2023
- 2023-09-14 CN CN202311181205.XA patent/CN117734525A/en active Pending
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