CN113922438A - High-power active equalization battery management system - Google Patents
High-power active equalization battery management system Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
- H02J7/0014—Circuits for equalisation of charge between batteries
- H02J7/0019—Circuits for equalisation of charge between batteries using switched or multiplexed charge circuits
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4207—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells for several batteries or cells simultaneously or sequentially
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00302—Overcharge protection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00304—Overcurrent protection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00308—Overvoltage protection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00309—Overheat or overtemperature protection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/0031—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits using battery or load disconnect circuits
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
- H01M2010/4271—Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
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- 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
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Abstract
A high-power active equalization battery management system is characterized in that: a single chip microcomputer is used as a system control main chip, and self-research software programs are integrated to flexibly control system management logic; based on a power electronic device MOSFET as a main power loop switch, and a plurality of bypass switches; the analog sampling chip adopts an analog switch as a sampling chip; the main control chip adopts an ARM core chip and is provided with a 12-bit ADC and a plurality of paths of CAN and RS485 serial ports for communication; the device supports the analog-to-digital conversion precision of more than 1%, has a 32-bit processor and 72MHZ, and can meet the requirements of acquisition and control of data information such as voltage, current, temperature and the like of 16 strings of battery monomers. The invention has the advantages that: the method is specially used for monitoring and protecting lithium batteries including lithium iron phosphate and ternary lithium batteries. The BMS manager belongs to a BMS manager product of a high-power energy storage system, and a single chip microcomputer controller is arranged in a circuit and can be communicated with a central controller of the energy storage system.
Description
Technical Field
The invention relates to the field of micro-grid energy storage and lithium battery intelligent management, in particular to a high-power active balancing battery management system.
Background
The current battery management system is mainly realized in a passive equalization mode, the battery management system can be started after the voltage of the battery reaches a certain threshold value, the equalization mode mainly adopts a passive device such as a resistor to carry out current limiting or discharging to achieve the battery balance of a string, generally, the equalization current ratio is small, and the equalization effect is limited.
Active equalization is also adopted in part of battery management systems, but a standby equalization power supply is adopted, and single-point standby power supply power supplement is required after the group string charging is ended. Such active equalization times are relatively long and the preliminary power supply is relatively complex to control and adds additional circuit cost. Most of the time is a spare unit, and no significance is brought to the operation of the circuit.
In a high-power energy storage system, due to the fact that the capacity of a single battery cell is not enough due to high capacity configuration, the utilization rate of a battery management system is increased, the batteries are connected in series after being connected in parallel, and the used battery management system cannot realize the distinguishing management of the batteries connected in parallel. The risk of internal short circuit between the parallel cells is easy to occur, so that the safety risk of the system is increased by using the method.
At present, a battery management system is actually in a hard link mode, the form of a string can not be changed after delivery, and the charging or discharging specific state of an electric core is uncertain during the battery operation information sampling overcharge. The measured voltage value cannot be accurately measured in an open circuit way. The accuracy of SOC estimation and battery information management is greatly affected, and the SOC estimation value is generally not higher than 10%. The judgment of the battery capacity is seriously influenced, and the working time and power are difficult to be pre-judged in advance according to the SOC data in the overcharging process.
The system is hard-linked in the grouping overcharge, so that the system is difficult to install when being linked to a high-voltage part. The capacity of a general large energy storage system can be more than 2MW of a single system, the voltage can generally reach more than 800V, and after the number of the cascade batteries is increased in the process of installation and overcharging, a special assembly tool is needed and the risk of safety accidents exists after the voltage exceeds a safe voltage value.
In a large energy storage system, safety protection wording is very important, a short-circuit protection function in a control mode cannot be achieved at present, and only a fuse can be used for protection of a physical pole. Once a short-circuit fault occurs, even if the fuse can be blown, the impact on the battery pack is very large. A protection mechanism for protecting quick response in a segmented mode is not possessed by the conventional BMS circuit, and the reliability of battery energy storage is required to be provided from the requirements of multiple aspects such as safety, fire protection and stability maintenance.
After the battery pack is chained, the consistency of the battery pack when leaving a factory can reach the standard of A-grade batteries very well due to the difference of the characteristics of the battery monomers in the process of overcharging, and the internal resistance can also change after the use cycle is many. This is the system will appear short plate, follow the wooden barrel and originally the monomer with the lowest internal resistance maximum capacity as the cut-off standard of discharge capacity. The battery monomer can not be actively discharged by-pass, and the maximum capacity of the system can not be exerted.
Disclosure of Invention
The invention aims to solve the problems and particularly provides a high-power active balanced battery management system.
The invention provides a high-power active equalization battery management system, which is characterized in that: a single chip microcomputer is used as a system control main chip, and self-developed software programs are integrated to flexibly control the system management logic; based on a power electronic device MOSFET as a main power loop switch, and a plurality of bypass switches; the analog sampling chip adopts an analog switch as a sampling chip; the main control chip adopts an ARM core chip and is provided with a 12-bit ADC and a plurality of paths of CAN and RS485 serial ports for communication; the analog-digital conversion precision is more than 1%, a 32-bit processor and 72MHZ are supported, and the acquisition and control of data information such as voltage, current, temperature and the like of 16 strings of battery monomers can be met;
the main power switch device adopts the MOSFET which is a super junction switch, the current capacity is very strong, the voltage resistance is within 80V, the current is 120A, the on-resistance is within 2 milliohm, a plurality of MOSFETs with the same specification are used in parallel, the current capacity is increased, and the control speed of the MOSFETs can reach the nanosecond level; the battery is similar to an ultra-large capacity capacitor, the charging and discharging voltage and current of the battery cannot have step changes, and the control precision can be controlled within millisecond range;
the analog sampling front end can be completed by adopting a field chip, manufacturers such as TI, NXP and the like have similar analog sampling front end chips, the price of the chips is relatively high, and the chips can be directly used as a control main body in a battery protection board system without a single chip microcomputer;
the battery management system is more reasonable in the aspect of cost by adopting the analog switch as a front-end sampling chip, serial communication is carried out between the analog switch and the single chip microcomputer to control the on-off of the analog switch in an interruption mode, a single battery is selected by a chip, and the voltage state of the battery is checked in turn.
The battery management system is a single-string system, the maximum number of the batteries connected in series is 16, the nominal total voltage is 51.2V of the lithium iron phosphate battery, the nominal total voltage is 59.2V of the ternary battery, and the current design value is the standard of a battery cell 1C; the battery management system can carry out cascade connection among systems, and at most 64 levels of cascade connection are realized; the home communication of the battery management system after the cascade connection adopts daisy chain form cascade connection; finally, the battery management system is linked with the EMS, and the communication line is isolated from the internal circuit of each battery management system;
the total voltage of the battery management system is acquired in two ways, wherein one way is that a voltage sampling line between the total positive voltage and the total negative voltage of the 16-string battery pack is subjected to equal proportional reduction through a divider; the second sampling mode is the addition calculation of the sampling voltage of each single battery; the two sampling modes are compared in the chip, if the deviation is larger than the threshold value, the system reports errors, and if the deviation is within the threshold value, the average value is taken.
The total current sampling mode of the battery management system is sectional collection, a direct current Hall collection is integrated in each battery management system, the current flowing through each battery in the series system is the same, and is the same as the total output current, so that the branch current is compared with the total current, if a large deviation exists, the phenomenon that the current in the energy storage system is shunted or internally short can be judged, and the total current in the energy storage system is the superposition of a plurality of branch currents.
The battery management system integrates 3 paths of temperature monitoring probes, one path of temperature monitoring probe is placed on a battery pole, the other path of temperature monitoring probe is placed in the internal space of a box body for installing the battery pack string, and the other path of temperature monitoring probe is placed on a metal shell of a battery at the center point of the battery pack string; during high-rate charge and discharge overcharge, the distribution points of heat generated by the battery core are different, the temperature of the common battery pole is the highest, the temperature of the battery shell is the second lowest, and the lowest temperature is the ambient temperature of the battery pack string; according to the temperature sampling data, configuring charging and discharging power through communication with an EMS; the working temperature of the battery pack string is controlled within the range of 0-60 ℃ due to the characteristics of the batteries;
when the temperature of the working environment of the battery pack is lower, the configured charging current is below 0.5C, and the discharging current is also controlled below 0.5C; when the environmental temperature of the battery pack string allows high-rate charge and discharge work, the battery pack string is configured to work at a rate of more than 1C; the specific configuration proportion can be specifically configured according to a battery specification book, and the parameters can be defined by a program.
Setting control logic of 'exit control without meeting the condition', namely setting the state of the battery into a plurality of simulation threshold intervals, normally working in the intervals, and judging to enter the next control logic when the battery is out of the set intervals; and when the batteries after special control and processing reach the set threshold standard, the batteries are switched into the group string again for working, and if the batteries after special control and processing still cannot reach the set threshold standard, the faults are judged and the batteries are bypassed permanently or the system alarms.
The active equalization mode is a dynamic bypass recombination mode; when the single battery reaches a charging cut-off point in the charging overcharge process, the connected battery is bypassed, other battery pack strings are charged continuously, and the bypass is not bypassed when the single battery is bypassed to a set certain number in sequence, but 4 batteries with the lowest voltage in the battery pack strings are dynamically selected to carry out low-current charging until all the batteries are marked to be fully charged;
an active equalization mode and a dynamic bypass recombination mode are adopted; when the single battery reaches a discharge cut-off point in the discharge overcharge process, bypassing the battery, continuously discharging other groups of strings, and stopping discharging the system after bypassing a certain number of the strings in sequence; the minimum input voltage requirement and the power requirement of a reference item are required for the maximum bypass quantity, and the minimum input voltage requirement and the power requirement are set by combining a battery discharge rate limiting factor; in some particular systems, a portion of the cells may be redundant in stock, and a backup cell may be accessed by bypassing the failed cell when a cell in the string fails.
The battery management system has a battery backup function, can exert advantages in large-scale energy storage projects, and can dynamically recombine and replace a fault battery when a single battery of a redundant part fails, so that the system can continuously and stably work, and the fault battery is replaced when the system is maintained; the battery management system is directly communicated with the energy storage system background in various modes and receives modes such as serial port communication, RS485 communication, CAN communication, dry nodes and the like; the communication speed can reach the ms level, and the dry node is adopted to transmit the protection instruction when sudden failure occurs, so that the speed is higher.
In the energy storage battery cluster integrated in a series connection mode, because the parallel batteries are not arranged, the controlled node is 1 independent battery, internal circulation does not occur in the same node, and mutual current flowing caused by the difference of the parallel batteries does not occur; when the system needs more capacity and power, the parallel connection of a plurality of clusters can be realized; the parallel nodes are provided with relays and fuses, so that each battery cluster can be controlled to fall out of the stored energy and can be connected or withdrawn as required.
The invention has the advantages that:
the intelligent management field of lithium batteries is specially used for monitoring and protecting lithium batteries including lithium iron phosphate and ternary lithium batteries. The BMS manager belongs to a BMS manager product of a high-power energy storage system, and a single chip microcomputer controller is arranged in a circuit and can be communicated with a central controller of the energy storage system.
Drawings
The invention is described in further detail below with reference to the following figures and embodiments:
FIG. 1 is an energy storage system frame diagram;
fig. 2 is a diagram of a battery management system BMS charging control logic architecture;
FIG. 3 is a functional block diagram of a battery management system;
FIG. 4 shows a diagram of an active equalization hardware base circuit;
fig. 5 is a battery management system BMS connection diagram;
fig. 6 is a schematic diagram of a battery management system BMS controller MCU.
Detailed Description
Examples
In order to make the objects, technical solutions and features of the present invention clearer, the following further explains the present invention with reference to the drawings and examples, and particularly describes a specific embodiment described herein for explaining the present invention only, and does not limit the present invention.
The battery management system adopts a 32-bit singlechip as a controller, is combined with an external sampling and power conversion circuit, can collect and control information such as voltage, current, temperature and the like of a controlled battery, is controlled by an EMS central controller, and manages and protects the battery pack string.
The battery management system can form a high-voltage energy storage power station system in a cascading mode, and the maximum cascading quantity is 64 levels (BMS). The single board can also be used as a battery manager of products such as two-wheeled vehicles, electric tools and the like, and when the single board is used, the power tube at the total negative end NC needs to be configured according to the use power.
When the single plate is used, when the external discharge power is within 1000W, the current can be realized by a single MOSFET within 30A, if the required power is larger, a plurality of MOSFETs can be used in parallel, and the through-current is increased
The battery management system integrates a 3-way NTC temperature sensor and a sampling chip MCP 9700A. The temperature sampling precision can reach +/-1 ℃, and the BMS can set a discharge limit power function and an over-temperature protection alarm threshold value through the temperature sampling value.
The threshold design is realized by measuring the surface temperature of a main power device, measuring the temperature of a battery pole and measuring the space environment temperature by using an NTC temperature detection probe, and the NTC temperature detection probe is used as a pure physical control method for over-temperature protection and fan refrigeration, wherein the working temperature point of a fan is set to be 40 ℃, and the battery at the over-temperature protection starting point is 60 ℃.
And the input and output current detection selects a sufficient range Hall device. The current value at the moment is obtained by carrying out a difference value technology with the reference voltage, a positive value is defined as charging input, a negative value is defined as discharging, Hull adopts a segmented range device to increase the sampling precision, and the current sampling precision can reach more than 1%.
The voltage detection uses a differential amplifier for analog sampling. And the negative electrode of the lowest string and the positive electrode of the highest string of the BMS are input to an ADC converter of the MCU after differential conversion. In addition, the voltage of each battery obtained by the analog switch can also play a role in calibration after being superposed. The voltage sampling precision of the battery pack can be more than 0.5%.
A battery management system designs various protection circuits. The protection circuit for the safe operation of the system protects the safe operation of the power device and the stable operation of the system. The overvoltage protection is carried out, and when the total voltage is higher than 60V in the charging and discharging processes, an alarm is given and the output is stopped; overtemperature protection is carried out, and when the internal temperature of the battery pack exceeds 60 ℃, an alarm is given and output is stopped; and (4) overcurrent protection, wherein the output overcurrent value is set to 125% of the rated maximum value. The system immediately alarms after being in an overcurrent state, and stops outputting if the overcurrent still disappears after continuously working for 1 minute, and stops alarming and continues working if the overcurrent disappears within 1 minute; and short-circuit protection, wherein the output short-circuit protection setting value is 150% of the rated maximum value. Once the output current of the system exceeds the short-circuit protection value, the system alarms and simultaneously stops outputting rapidly, and the response time is required to be less than 100 nS; and outputting undervoltage protection, wherein when the voltage of the direct current bus is lower than the voltage of the lowest discharge point of the cell group, the system gives an alarm and stops outputting.
The output current sharing setting of the system should consider two aspects, one is the impedance difference of the battery units, and the other is the voltage difference between the battery units. Two sets of driving circuits are needed, firstly, when the output current difference of the parallel battery units is not large (temporarily set by 10%) and not larger than a rated output value, the PWM controller is not started, the FPGA drives the discharging MOSFET to be opened for a long time, and the current is not equalized to discharge. The PWM controller is in the SHUTDOWN state at this time. And secondly, when the output current is detected to be serious, the balance control circuit is triggered to simultaneously pull down the long-open high level signal. The unit enters a current-sharing output state.
The fan selects 48V voltage grade, and the power and the air exhaust quantity of the fan are selected according to the heat loss converted from the efficiency. The method is characterized in that 2 fans are preset to dissipate heat in a pulling and pushing mode. The driving mode adopts a constant resistance and current limiting mode to avoid the magnetic saturation of the fan; the fan is set to start after the temperature of the battery exceeds 40 ℃, and stop working when the temperature is lower than 25 ℃.
Safety regulation consideration is added in the design process, and the system is required to pass the test of EMI and EMS; and a TVS for lightning protection and an ESD for static electricity protection are added at the external communication interface. The board card and the managed battery pack are installed nearby, and the signal wire is linked in a twisted pair mode.
And a diode with enough power is connected in series on the output + electrode of the battery pack after reverse connection prevention, and the diode is used for reverse connection prevention. A slow-breaking fuse is connected in series with the main loop, and the value is selected to be above an overcurrent protection value (125%) and close to a short-circuit protection value (150%). The main function of the physical protection is to prevent fire when the OCP fails.
The switch of the main circuit and the bypass switch of the battery pack string can not be conducted simultaneously in the working process, and the anti-common circuit is needed to prevent the fault of short circuit of the electric core caused by simultaneous conduction of the battery charging and discharging switch and the bypass switch. The control can be done by OR gate or implemented by inverse logic of high and low levels. When the battery charge-discharge switch (main switch) is turned on, the bypass switch is not turned on.
The BQ24735 charging circuit is used for dynamic equalization charging of battery units, can charge 4 series battery packs at most at the same time, and has an output voltage of 19V (which can be set) at most and an output charging current value which can be configured by a controller (the maximum current is 8A).
The selected power electronic devices are all conventional devices, the price and the purchase are both superior, core devices such as an analog switch, a single chip microcomputer and a metal-oxide-semiconductor field effect transistor (MOSFET) can be made into a home-made mode, and various specifications and function adjustment can be made according to different use environments
The battery manager system is called BMS for short, external interfaces are provided with +, -, POWER drive x16, BYPASS drive x16, serial ports, battery voltage sampling flat cables and the like, one BMS controls the number of batteries to be 16 at most, and 16 batteries in the battery manager system need to be in a series structure. The manageable number can be selected from 4-16 sections and is selected within the range of the maximum management capability. The battery monitoring flat cable terminal is inserted above the circuit board, the other terminal needing to be linked with the battery is an O-shaped cold pressing terminal, the terminal is well welded with the tail end of a lead through soldering tin, and the wire size is made according to the position of the battery to be adopted.
After the battery management system is used for manufacturing the plate, because the power device is arranged on two sides, the plate card is extruded and fixed by two plate cards made of aluminum materials, so that the plate cards play roles of reinforcing, preventing collision and electric shock on one hand, and can play a role of pasting and radiating on the other hand, and the heat-conducting silicon rubber sheet is required to be coated between the MOSFET tube and the aluminum plate and then is pressed tightly by a bolt. The surface aluminum shell of the BMS conducts heat when the BMS runs at high power, and the BMS cannot be attached to a battery shell for installation.
The active equalization circuit of the invention adopts a large number of semiconductor devices as control switches, can dynamically reconstruct the arrangement mode of the batteries and bypass the fault batteries out of a main loop. The system can continuously run and dynamically compensate on the premise of not influencing the normal work of the system. And (4) repairing the capacity deviation of the battery during the charging overcharge, and selecting the lowest 4 batteries for compensation charging by polling the voltage of the single batteries in the battery pack string. And until the polling selects the lowest 1 battery for compensation charging until the battery is full.
Dynamic compensation is a control logic that quickly bypasses the compensation or flag for cells that are outside of a preset range, whether during charge overcharge or discharge overcharge.
The battery management system does not need to consider the risk of high-voltage operation in the assembly production link, because before the system is not electrified, the driving of the control level does not output, at the moment, the MOSFET is in a closed state, and the batteries in the system are isolated by the MOSFET without forming a connection, so that the battery management system does not have electrical performance. The system voltage is built up only when a charge or discharge command is executed after the system is started, and the MOSFETs in the circuit are turned on.
The battery management system disclosed by the invention has the advantages that the requirement on the corresponding controlled battery voltage range is not strict, all battery products such as lead acid, lithium iron phosphate, ternary lithium and the like which are in the current market are basically compatible, and the battery management system can be applied to a gradient battery. Because the consistency of the echelon batteries is difficult to ensure, the wooden barrel effect is more prominent, and the battery pack has the functions of active bypass and balance, so that the individual capacity of the batteries can be exerted to the maximum.
The maximum active equalization power level can reach the main string 100A, and the magnitude of the bypass fine equalization 10A is an energy standard that other active equalization BMS cannot reach. And no additional standby power supply equipment is required.
The system main controller has an online upgrading function, can download and update the control program through a serial port without stopping, and can download and update online through the super terminal.
The patent of the invention does not specifically define the type and power level of the BMS, only explains the general method and technical characteristics of the invention, and all the using modes of the battery management system with the bypass function by adopting the active balancing of the invention are within the protection scope of the patent.
BMS, english acronym for high power active balancing battery management system.
Claims (8)
1. A high-power active equalization battery management system is characterized in that: a single chip microcomputer is used as a system control main chip, and self-research software programs are integrated to flexibly control system management logic; based on a power electronic device MOSFET as a main power loop switch, and a plurality of bypass switches; the analog sampling chip adopts an analog switch as a sampling chip; the main control chip adopts an ARM core chip and is provided with a 12-bit ADC and a plurality of paths of CAN and RS485 serial ports for communication; the analog-digital conversion precision is more than 1%, a 32-bit processor and 72MHZ are supported, and the acquisition and control of data information such as voltage, current, temperature and the like of 16 strings of battery monomers can be met;
the main power switch device adopts the MOSFET which is a super junction switch, the current capacity is very strong, the voltage resistance is within 80V, the current is 120A, the on-resistance is within 2 milliohm, a plurality of MOSFETs with the same specification are used in parallel, the current capacity is increased, and the control speed of the MOSFETs can reach the nanosecond level; the battery is similar to an ultra-large capacity capacitor, the charging and discharging voltage and current of the battery cannot have step change, and the control precision can be controlled within millisecond range;
the analog sampling front end can be completed by adopting a field chip, manufacturers such as TI, NXP and the like have similar analog sampling front end chips, the price of the chips is relatively high, and the chips can be directly used as a control main body in a battery protection board system without a single chip microcomputer.
2. The high power active balancing battery management system according to claim 1, characterized in that:
the battery management system is a single-string system, the maximum number of the batteries connected in series is 16, the nominal total voltage is 51.2V of the lithium iron phosphate battery, the nominal total voltage is 59.2V of the ternary battery, and the current design value is the battery core 1C standard; the battery management system can carry out cascade connection among systems, and at most 64 levels of cascade connection are realized; the home communication of the battery management system after the cascade connection adopts daisy chain form cascade connection; finally, the battery management system is linked with the EMS, and the communication line is isolated from the internal circuit of each battery management system;
the total voltage of the battery management system is acquired in two ways, wherein one way is that a voltage sampling line between the total positive voltage and the total negative voltage of the 16-string battery pack is subjected to equal proportional reduction through a divider; the second sampling mode is the addition calculation of the sampling voltage of each single battery; and comparing the two sampling modes in the chip, reporting errors by the system if the deviation is greater than a threshold value, and taking an average number if the deviation is within the threshold value.
3. The high power active balancing battery management system according to claim 1, characterized in that:
the total current sampling mode of the battery management system is sectional collection, a direct current Hall collection is integrated in each battery management system, the current flowing through each battery in the series system is the same, and the current is the same as the total output current, so that the branch current is compared with the total current, if a large deviation exists, the phenomenon that the current in the energy storage system is shunted or internally short can be judged, and the total current in the energy storage system is the superposition of a plurality of branch currents.
4. The high power active balancing battery management system according to claim 1, characterized in that: the battery management system integrates 3 paths of temperature monitoring probes, one path of temperature monitoring probe is placed on a battery pole, the other path of temperature monitoring probe is placed in the internal space of a box body for installing the battery pack string, and the other path of temperature monitoring probe is placed on a metal shell of a battery at the center point of the battery pack string; during high-rate charge and discharge overcharge, the distribution points of heat generated by the battery core are different, the temperature of the common battery pole is the highest, the temperature of the battery shell is the second lowest, and the lowest temperature is the ambient temperature of the battery pack string; configuring charge and discharge power through communication with EMS according to the temperature sampling data; the working temperature of the battery pack string is controlled within the range of 0-60 ℃ due to the characteristics of the batteries;
when the temperature of the working environment of the battery pack is lower, the configured charging current is below 0.5C, and the discharging current is also controlled below 0.5C; when the ambient temperature of the battery pack string allows high-rate charge and discharge work, the battery pack string is configured to work at a rate of more than 1C; the specific configuration proportion can be specifically configured according to a battery specification book, and the parameters can be defined by a program.
5. The high power active balancing battery management system according to claim 1, characterized in that: setting control logic of 'exit control without meeting the condition', namely setting the state of the battery into a plurality of simulation threshold intervals, normally working in the intervals, and judging to enter the next control logic when the battery is out of the set intervals; and when the batteries after special control and processing reach the set threshold standard, the batteries are connected into the group string again for working, and if the batteries after special control and processing still cannot reach the set threshold standard, the failure is judged and the batteries are bypassed permanently or the system alarms.
6. The high power active balancing battery management system according to claim 1, characterized in that: the active equalization mode is a dynamic bypass recombination mode; when the single battery reaches a charging cut-off point in the charging overcharge process, the battery is bypassed, other battery pack strings are continuously charged, and the bypass is not bypassed when the battery pack strings are bypassed to a set certain number in sequence, but 4 batteries with the lowest voltage in the battery pack strings are dynamically selected to carry out low-current charging until all the batteries are fully marked;
an active equalization mode and a dynamic bypass recombination mode are adopted; when the single battery reaches a discharge cut-off point in the discharge overcharge process, bypassing the battery, continuously discharging other groups of strings, and stopping discharging the system after bypassing a certain number of the strings in sequence; the minimum input voltage requirement and the power requirement of the reference items required by the maximum bypass quantity are set by combining with the battery discharge rate limiting factor; in some particular systems, a portion of the cells may be redundant in stock, and a backup cell may be accessed by bypassing the failed cell when a cell in the string fails.
7. The high power active balancing battery management system according to claim 1, characterized in that: the battery management system has a battery backup function, can play an advantage in large-scale energy storage projects, and can dynamically recombine and replace a fault battery when a single battery of a redundant part fails, so that the system can continuously and stably work, and the fault battery is replaced when the system is maintained; the battery management system is directly communicated with the energy storage system background in various modes and receives serial port communication, RS485 communication, CAN communication, dry node and other modes; the communication speed can reach the ms level, and the dry node is adopted to transmit the protection instruction when sudden failure occurs, so that the speed is higher.
8. The high power active balancing battery management system according to claim 1, characterized in that: in the energy storage battery cluster integrated in a series connection mode, because the parallel batteries are not arranged, the controlled node is 1 independent battery, internal circulation does not occur in the same node, and mutual current flowing caused by the difference of the parallel batteries does not occur; when the system needs more capacity and power, the parallel connection of a plurality of clusters can be realized; the parallel nodes are provided with relays and fuses, so that each battery cluster can be controlled to fall out of the stored energy and be connected or disconnected as required.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114914562A (en) * | 2022-05-19 | 2022-08-16 | 西安合能电气科技有限公司 | Hardware system, management method and detection device for realizing bypass, current sharing and voltage stabilization of single battery cell based on algorithm |
| CN115360798A (en) * | 2022-10-19 | 2022-11-18 | 中安芯界控股集团有限公司 | Online balancing method for battery clusters in battery energy storage system |
| CN116979164A (en) * | 2023-09-21 | 2023-10-31 | 共模半导体技术(苏州)有限公司 | Chip management system for multi-cell serial structure |
| CN117171588A (en) * | 2023-11-02 | 2023-12-05 | 吉林省有继科技有限公司 | Method for detecting gradient utilization faults of power battery |
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- 2021-08-23 CN CN202110968218.6A patent/CN113922438A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114914562A (en) * | 2022-05-19 | 2022-08-16 | 西安合能电气科技有限公司 | Hardware system, management method and detection device for realizing bypass, current sharing and voltage stabilization of single battery cell based on algorithm |
| CN115360798A (en) * | 2022-10-19 | 2022-11-18 | 中安芯界控股集团有限公司 | Online balancing method for battery clusters in battery energy storage system |
| CN115360798B (en) * | 2022-10-19 | 2023-02-28 | 中安芯界控股集团有限公司 | Online balancing method for battery clusters in battery energy storage system |
| CN116979164A (en) * | 2023-09-21 | 2023-10-31 | 共模半导体技术(苏州)有限公司 | Chip management system for multi-cell serial structure |
| CN116979164B (en) * | 2023-09-21 | 2023-12-29 | 共模半导体技术(苏州)有限公司 | Chip management system for multi-cell serial structure |
| CN117171588A (en) * | 2023-11-02 | 2023-12-05 | 吉林省有继科技有限公司 | Method for detecting gradient utilization faults of power battery |
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