CN111029666B - Modularized active equalization battery management system and management method thereof - Google Patents

Modularized active equalization battery management system and management method thereof Download PDF

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CN111029666B
CN111029666B CN201911059450.7A CN201911059450A CN111029666B CN 111029666 B CN111029666 B CN 111029666B CN 201911059450 A CN201911059450 A CN 201911059450A CN 111029666 B CN111029666 B CN 111029666B
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voltage
battery
switch
equalizer
change
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CN111029666A (en
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彭建
于安元
梁文剑
张矩鹏
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彭建
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/42Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4207Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells for several batteries or cells simultaneously or sequentially
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/42Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/425Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/42Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/44Methods for charging or discharging
    • H01M10/441Methods for charging or discharging for several batteries or cells simultaneously or sequentially
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/42Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/46Accumulators structurally combined with charging apparatus
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/42Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/48Accumulators combined with arrangements for measuring, testing or indicating condition, e.g. level or density of the electrolyte
    • H01M10/482Accumulators combined with arrangements for measuring, testing or indicating condition, e.g. level or density of the electrolyte for several batteries or cells simultaneously or sequentially
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H02J7/0014Circuits for equalisation of charge between batteries
    • H02J7/0019Circuits for equalisation of charge between batteries using switched or multiplexed charge circuits
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H02J7/0024Parallel/serial switching of connection of batteries to charge or load circuit
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/42Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/425Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • H01M2010/4271Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

Abstract

The invention discloses a modular active equalization battery management system and a management method thereof.A battery module consisting of M single batteries which are connected in series in sequence is connected, and the battery module comprises a control unit and a module management unit matched with the battery module; each module management unit comprises a power supply unit, a voltage acquisition unit and a current sampling unit, the power supply unit is connected with an equalizer, and the power supply unit, the voltage acquisition unit, the current sampling unit and the equalizer are all in communication connection with the control unit. Managing and actively balancing N × M series batteries, adopting 2 groups of series-connected energy storage elements with large capacity and long service life, and realizing active bidirectional energy transfer with large current and high efficiency by parallel charging and series discharging; and the balance of the electric quantity among the modules is realized through the balance scheduling among the modules.

Description

Modularized active equalization battery management system and management method thereof
Technical Field
The invention belongs to the technical field of battery management systems, relates to a modular active equalization battery management system and further relates to a management method of the management system.
Background
Currently, the new energy industry is changing the old energy production and utilization modes, and new energy power generation represented by photovoltaic power generation and wind power generation is gradually replacing coal-fired power generation; new vehicles represented by pure electric vehicles are gradually replacing petrochemical fuel vehicles. The advanced electrochemical energy storage technology is one of the foundation stones for continuous progress and expansion of new energy industries.
The new energy automobile is the main driving force for the progress of the advanced electrochemical energy storage technology, wherein a power lithium (ion) battery becomes the mainstream of the machine, and the new energy automobile has the advantages of high energy density, long cycle life, no memory effect, no pollution and the like. Ternary lithium batteries and lithium iron phosphate batteries are two main branches of power lithium batteries.
The intermittent characteristic of new energy power generation restricts the installed scale of the new energy power generation to be further expanded, the consumption capacity of the existing power grid is obviously insufficient, and one of the solutions is to build a large-scale energy storage system to balance the loads of power generation and power utilization.
A large-scale lithium battery energy storage system is formed by connecting a plurality of single batteries in series into a module, connecting a plurality of modules in series into a battery cluster, and connecting a plurality of battery clusters in parallel into a large-scale battery system. Due to differences among the single batteries, such as capacity differences, internal resistance differences, voltage platform differences, polarization differences, self-discharge rate differences and the like, various inconsistencies exist in battery systems after series connection. The current and voltage parameters of the battery system in the charging and discharging process are consistent with those of each monomer in the series system, and the inconsistency of the consistency requirement and the system is a pair of main contradictions. With the increase of the use times of the system, the inconsistency of various parameters of the system can be continuously expanded, so that the cycle life of the system is greatly shortened, the available capacity is greatly reduced, and the system power is greatly reduced.
The battery management system is used as the brain of the battery system to monitor and manage various electrical parameters of the battery, and is an indispensable component for ensuring the normal operation of the battery system. The basic functions of the battery management system include voltage and current monitoring, over-voltage and under-voltage protection and the like, and the advanced functions include SOC prediction, battery equalization, internal resistance test, SOH management and the like. The battery balancing function is a key core function for improving system difference and regulating consistency. The shallow layer of the battery equalization aims at voltage equalization, so that the voltages of all batteries are the same, and the deep layer aims at realizing capacity equalization and making up for the battery capacity short plate. High-efficiency large-current balance is an important means for repairing the difference of a battery system, the maintenance cost of the system can be effectively reduced, and the cycle life of the system is greatly prolonged.
The main stream vehicle battery management system is mature in the functions of basic function, voltage monitoring and overvoltage and undervoltage protection, SOC prediction, passive equalization and the like, an active equalization function is provided by part of high-end products, and the equalization current reaches 2 amperes. However, the current battery management system is deficient in application to a large-scale energy storage system, cannot realize high-efficiency large-current (tens of amperes) balance and cross-module balance, cannot perform single-battery SOC prediction in a balance action mode, and the like.
Disclosure of Invention
The invention aims to provide a modular active balancing battery management system, which solves the problem that the battery management system in the prior art cannot realize cross-module balancing.
The technical scheme adopted by the invention is that a modularized active equalization battery management system is connected with M battery modules formed by sequentially connecting N single batteries in series, and comprises a control unit and a module management unit matched with the battery modules, wherein N, M are all any natural number greater than 1;
each module management unit comprises a power supply unit, a voltage acquisition unit and a current sampling unit, wherein the power supply unit is connected with an equalizer, the power supply unit is used for connecting or disconnecting the equalizer and each single battery, the voltage acquisition unit is used for acquiring the voltage of each single battery, and the current sampling unit is used for acquiring the charging and discharging current of each single battery; the power supply unit, the voltage acquisition unit, the current sampling unit and the equalizer are all in communication connection with the control unit.
The invention is also characterized in that:
the control unit comprises a main control board, the main control board is in communication connection with embedded microcontrollers, the number of the embedded microcontrollers is the same as that of the module management units, and the main control board is in communication connection with the embedded microcontrollers respectively; the power supply unit, the voltage acquisition unit, the current sampling unit and the equalizer are all in communication connection with the corresponding embedded microcontrollers.
Each equalizer comprises a first change-over switch connected with the power supply unit, the first change-over switch is connected with two energy storage elements connected in series, a fourth change-over switch is connected between the two energy storage elements, each energy storage element is connected with a second change-over switch used for controlling the charge-discharge mode of the energy storage element, each energy storage element is further connected with a third change-over switch, and the third change-over switches in each module management unit are all connected.
The power supply unit comprises N anode battery equalization switch channels and N cathode battery equalization switch channels, one end of each anode battery equalization switch channel is connected with the anode of a single battery, and the other end of each anode battery equalization switch channel is connected with a first equalization bus; one end of each negative electrode battery equalization switch channel is connected with the negative electrode of the single battery, the other end of each negative electrode battery equalization switch channel is connected with a second equalization bus, and the positive electrode battery equalization switch channel and the negative electrode battery equalization switch channel are in communication connection with the embedded microcontroller.
The first switch comprises a first on-off switch and a second on-off switch, one end of the first on-off switch is connected with the first balance bus, and the other end of the first on-off switch is connected with one energy storage element; one end of the second on-off switch is connected with the second equalizing bus, and the other end of the second on-off switch is connected with the other energy storage element.
The current sampling unit comprises a current sensor which is connected to the tail end of the second equalization bus.
Another object of the present invention is to provide a modular active balancing battery management method.
The invention adopts another technical scheme that a modular active balancing battery management method adopts the management system and comprises the following steps:
step 1, a main control board compares the total voltage of a battery module transmitted by each embedded microcontroller to obtain a voltage difference value between a maximum voltage battery module and a minimum voltage battery module, and judges whether the voltage difference value is greater than a preset inter-module balance starting voltage or not, a module management unit corresponding to the maximum voltage battery module is marked as X, and a module management unit corresponding to the minimum voltage battery module is marked as Y;
step 2, if the voltage difference value is larger than the balance starting voltage between the preset modules, the main control board sends a discharge instruction to the embedded microcontroller corresponding to the X, the embedded microcontroller controls the single battery with the highest voltage to discharge, and the electric quantity is transferred to the equalizer until the voltage of the equalizer is balanced with the voltage of the single battery with the highest voltage;
step 3, the main control board sends a charging instruction to the embedded microcontroller corresponding to the Y, and the electric quantity is transferred from the equalizer in the X to the equalizer in the Y until the voltage of the equalizer in the X and the voltage of the equalizer in the Y are balanced;
and 4, the embedded microcontroller corresponding to the Y sends a discharging instruction to the equalizer, and the equalizer transfers the electric quantity to the single battery with the lowest voltage, so that the voltage of the equalizer and the voltage of the lowest single battery are balanced.
The step 2 specifically comprises the following steps:
the method comprises the steps of starting a positive electrode battery equalization switch channel and a negative electrode battery equalization switch channel of a highest-voltage single battery, starting a first on-off change-over switch, a second on-off change-over switch and two second change-over switches, closing a fourth change-over switch and two third change-over switches, transferring the electric quantity of the highest-voltage single battery to two energy storage elements respectively until the voltages of the two energy storage elements are balanced with the voltage of the highest-voltage single battery respectively, closing the first on-off change-over switch and the second on-off change-over switch, and starting the fourth change-over switch and the two third change-over switches.
The step 3 specifically comprises the following steps:
and closing the first on-off change-over switch, the second on-off change-over switch and the fourth change-over switch, and opening the two second change-over switches and the two third change-over switches until the total voltage of the two energy storage elements in the X and the total voltage of the two energy storage elements in the Y are balanced.
The step 4 specifically comprises the following steps:
and starting a positive battery equalization switch channel and a negative battery equalization switch channel of the lowest-voltage single battery, starting a first on-off change-over switch, a second on-off change-over switch and a fourth change-over switch, and closing two second change-over switches and two third change-over switches, so that the total voltage of two energy storage elements and the electric quantity of the single battery are balanced.
The invention has the beneficial effects that: the battery management system manages and actively balances the N × M series batteries, adopts 2 groups of series-connected energy storage elements with large capacity and long service life, and realizes active bidirectional energy transfer with large current and high efficiency by parallel charging and series discharging; the electric quantity balance among the modules is realized through the balance scheduling among the modules; the current sensor is arranged at the tail end of the second balance bus to measure the single-cell balance electric quantity transfer, the whole SOC measurement data is integrated, and more accurate single-cell battery SOC prediction can be achieved. The battery management system method can realize high-efficiency large-current balance.
Drawings
Fig. 1 is a schematic structural diagram of a modular active balancing battery management system according to the present invention;
FIG. 2 is a schematic diagram of a control unit in a modular active balancing battery management system according to the present invention;
FIG. 3 is a diagram of the relationship between the PWM signal and the balancing current of a modular active balancing battery management system according to the present invention;
fig. 4 is a schematic structural diagram of a module management unit in an embodiment of a modular active balancing battery management system according to the present invention;
FIG. 5 is a schematic diagram of an equalizer in an embodiment of a modular active equalization battery management system of the present invention;
fig. 6 is a schematic diagram of an equalizing process of an embodiment of the modular active equalization battery management system according to the present invention.
In the figure, the intelligent energy storage device comprises a control unit 1, a module management unit 2, a main control board 3, an embedded microcontroller 4, a power supply unit 5, a voltage acquisition unit 6, a current sampling unit 7, an equalizer 8, a first change-over switch 9, a first on-off change-over switch 9-1, a second on-off change-over switch 9-2, an energy storage element 10, a fourth change-over switch 11, a second change-over switch 12, a third change-over switch 13, a positive battery equalization switch channel 14, a negative battery equalization switch channel 15, a first equalization bus 16 and a second equalization bus 17.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
A modularized active equalization battery management system is shown in figure 1, and M battery modules formed by sequentially connecting N single batteries in series are connected, as shown in figure 2, the modularized active equalization battery management system comprises a control unit 1, a module management unit 2 matched with the battery modules, and N, M which are all any natural number larger than 1; the control unit 1 comprises a main control board 3, the main control board 3 is connected with a plurality of embedded microcontrollers 4 through an isolated CAN (controller area network) transceiver circuit in a communication mode, and the main control board 3 is respectively connected with the plurality of embedded microcontrollers 4 through the isolated CAN transceiver circuit. The model STM32F4 series development board of the main control board 3, the model of the embedded microcontroller 4 is ARM Cortex-M3 CPU.
Each module management unit 2 comprises a power supply unit 5, a voltage acquisition unit 6 and a current sampling unit 7, the power supply unit 5 is connected with an equalizer 8, the power supply unit 5 is in communication connection with the embedded microcontroller 4, and the power supply unit 5 enables the equalizer 8 to be connected with or disconnected from each single battery under the control of the embedded microcontroller 4; the voltage acquisition unit 6 is in communication connection with the embedded microcontroller 4, and the voltage acquisition unit 6 is used for acquiring the voltage of each single battery. The current sampling unit 7 is in communication connection with the embedded microcontroller 4 and is used for collecting the charge and discharge current of each single battery and feeding back the charge and discharge current to the embedded microcontroller 4 to obtain the balanced transfer capacity through integration. The embedded microcontroller 4 and the module management unit 2 are installed in the lower computer.
The power supply unit 5 comprises N anode battery equalization switch channels 14 and N cathode battery equalization switch channels 15, one end of each anode battery equalization switch channel 14 is connected with the anode of a single battery, and the other end of each anode battery equalization switch channel is connected with a first equalization bus 16; one end of each negative electrode battery equalization switch channel 15 is connected with the negative electrode of the single battery, the other end of each negative electrode battery equalization switch channel is connected with a second equalization bus 17, and the positive electrode battery equalization switch channel 14 and the negative electrode battery equalization switch channel 15 are in communication connection with the embedded microcontroller 4. The positive battery equalization switch channel 14 and the negative battery equalization switch channel 15 are reversely arranged in pairs by adopting low-resistance high-current MOSFETs, and the MOSFETs are connected with a driving circuit.
Each equalizer 8 comprises a first change-over switch 9 connected with the power supply unit 5, each first change-over switch 9 comprises a first on-off change-over switch 9-1 and a second on-off change-over switch 9-2, the first on-off change-over switch 9-1 is Q1, the second on-off change-over switch 9-2 is Q2, one end of each first on-off change-over switch 9-1 is connected with the first equalization bus 16, and the other end of each first on-off change-over switch 9-1 is connected with one energy storage element 10; one end of the second on-off switch 9-2 is connected with the second equalizing bus 17, and the other end is connected with the other energy storage element 10. The first switch 9 is connected with two energy storage elements 10 connected in series, the two energy storage elements 10 connected in series are respectively C1 and C2, Q1 is connected in series with C2, and Q1 is used for controlling connection or disconnection of C2 and the first equalizing bus 16; q2 is connected in series with C1, Q2 is used to control the connection or disconnection of C1 to the second equalization bus 17; a fourth change-over switch 11 is connected between the two energy storage elements 10, the fourth change-over switch 11 is Q3, the fourth change-over switch 11 is used for realizing the series connection or the parallel connection of the two energy storage elements 10, and Q1, C2, C1, Q2 and the single battery form a closed loop. Each energy storage element 10 is connected with a second change-over switch 12 for controlling the charge-discharge mode thereof, the second change-over switch 12 connected in series with C2 is Q5, the second change-over switch 12 connected in series with C1 is Q4, each energy storage element 10 is further connected with a third change-over switch 13, the third change-over switches 13 in each module management unit 2 are all connected, the third change-over switch 13 is used for energy transfer between two module management units 2, the third change-over switch 13 connected in series with C2 is Q7, and the third change-over switch 13 connected in series with C1 is Q6.
When the C1 and the C2 are charged in parallel, Q3 is disconnected, Q4 and Q5 are closed, the charging time is controlled, and whether the battery is fully charged or not can be confirmed by weakening the current, so that the energy storage element is close to the voltage of the battery; when the C1 and the C2 are discharged in series, Q3 is closed, Q4 and Q5 are opened, the discharging time is controlled, whether the discharge is empty or not is confirmed by weakening of current, and the voltage of the energy storage element is gradually reduced from 2 times of voltage to be close to the voltage of the battery. The energy storage elements 10 are used as a transfer container for transferring the energy of the battery, generally, a high-capacity and long-life super capacitor or a rechargeable battery is selected, and each group of energy storage elements is connected in series by a plurality of single sections to realize voltage matching; 2 groups of series energy storage elements store electric energy in a parallel state, and then the MOSFET switch Q3 is switched to a series state through a charging and discharging mode to pull high voltage, so that the electric energy can be transferred to a battery through discharging; the duty ratio of the MOSFET is controlled by PWM, and the charging and discharging current of the series energy storage element is controlled, so that the instant excessive charging and discharging current is prevented.
The first on-off switch 9-1, the second on-off switch 9-2, the two second switches 12, the two third switches 13 and the fourth switch 11 are all in communication connection with the embedded microcontroller 4. The first on-off switch 9-1, the second on-off switch 9-2, the two second switches 12, the two third switches 13 and the fourth switch 11 are all MOSFET switches, and the MOSFET switches are connected with a driving circuit. The embedded microcontroller 4 adopts a PWM control program to control the first on-off switch 9-1, the second on-off switch 9-2, the two second switches 12, the two third switches 13 and the fourth switch 11 to realize the control of charging and discharging current.
The current sampling unit 7 comprises a current sensor connected at the end of the second equalization bus 17. The charge and discharge capacity of each battery is measured by setting a balanced current integration program in the embedded microcontroller 4, and the single battery SOCi is obtained after the main control board 3 accumulates the whole SOC. The single battery SOCi is the sum of the SOC of the whole system and the balance capacity of the single battery transfer.
A modularized active equalization battery management method adopts the management system and comprises the following steps:
step 1, a main control board 3 compares the total voltage of the battery modules transmitted by each embedded microcontroller 4 to obtain the voltage difference value between the maximum voltage battery module and the minimum voltage battery module, and judges whether the voltage difference value is greater than the balance starting voltage between preset modules, the module management unit 2 corresponding to the maximum voltage battery module is marked as X, and the module management unit 2 corresponding to the minimum voltage battery module is marked as Y;
step 2, if the voltage difference value is larger than the balance starting voltage between the preset modules, the main control board 3 sends a discharge instruction to the embedded microcontroller 4 corresponding to the X, the embedded microcontroller 4 controls the single battery with the highest voltage to discharge, the electric quantity is transferred to the equalizer 8, and the voltage of the equalizer 8 is balanced with the voltage of the single battery with the highest voltage;
specifically, in X, the embedded microcontroller 4 turns on the positive electrode cell balancing switch channel 14 and the negative electrode cell balancing switch channel 15 of the highest voltage cell, turns on Q1 and Q2, turns off Q3, Q6 and Q7, and controls to turn on Q4 and Q5 by using PWM signals, so that C1 and C2 are in a parallel state, and the electric quantity of the highest voltage cell is respectively transferred to C1 and C2 until the voltages Vc2 of the voltages Vc1 and C2 of C1 are respectively balanced with the voltage Vx of the highest voltage cell, that is, Vc1, Vc2 ≈ Vx, turns off Q1 and Q2, and turns on Q6, Q7 and Q3.
Step 3, the main control board 3 sends a charging instruction to the embedded microcontroller 4 corresponding to the Y, and the electric quantity is transferred from the equalizer 8 in the X to the equalizer 8 in the Y until the voltage of the equalizer 8 in the X and the voltage of the equalizer 8 in the Y are balanced;
in Y, the embedded microcontroller 4 turns off Q1, Q2, Q3, turns on Q4, Q5, Q6, Q7, and controls Q3 with the PWM signal until the total voltage of the two energy storage elements 10 in X and the total voltage of the two energy storage elements 10 in Y reach a balance Vc1, Vc2 ≈ Vx.
And 4, the embedded microcontroller 4 corresponding to the Y sends a discharging instruction to the equalizer 8, and the equalizer 8 transfers the electric quantity to the single battery with the lowest voltage, so that the voltage of the equalizer 8 and the voltage of the lowest single battery are balanced.
In Y, the embedded microcontroller 4 starts the positive cell balancing switch channel 14 and the negative cell balancing switch channel 15 of the lowest voltage cell, starts Q1, Q2, and Q3, connects C1 and C2 in series to pull high voltage, closes Q4, Q5, Q6, and Q7, and controls Q3 by using PWM signals, so that the total voltage of the two energy storage elements 10 and the cell electric quantity reach a balance of Vc1, Vc2 ≈ 1/2 ≈ Vy.
The PWM signal is adopted to control the charging and discharging current of the equalizer, so as to prevent the current impact from occurring at the moment when the super capacitor is switched on. The initial signal of PWM is 5% duty ratio, and the duty ratio is increased to 95% according to the step length, the step length is controlled by PID, the initial current can be reduced to below 30A, and the charging and discharging current range is 10A-30A. The PWM signal versus equalization current is shown in fig. 3.
Through the mode, the battery management system manages and actively balances the N × M series batteries, adopts 2 groups of series-connected energy storage elements with large capacity and long service life, and realizes active bidirectional energy transfer with large current and high efficiency through parallel charging and series discharging; the electric quantity balance among the modules is realized through the balance scheduling among the modules; the current sensor is arranged at the tail end of the second balance bus to measure the whole SOC and measure the single-cell balance electric quantity transfer, the whole SOC measurement data is integrated, and more accurate single-cell battery SOC prediction can be achieved. (ii) a The battery management system method can realize high-efficiency large-current balance and cross-module balance.
Examples
The invention takes a 128-string large-scale battery management system for energy storage as an embodiment, and comprises 8 16-string module management units and 1 main control board, namely M is 8, N is 16, the capacity of each battery is 200Ah, the nominal voltage of a single battery is 3.2V, the charging cut-off voltage is 3.7V, the nominal voltage of a module is 51.2V, and the nominal voltage of a system is 409.6V.
The 16-string module management unit 2 manages 16 strings of battery modules B1-B16, and the module management unit 2 is directly powered by the total anode and cathode of the battery modules; each battery of the 16-string battery module is led out with a cable to 17 access terminals of the module management unit, and the cables are used as a voltage sampling channel, a positive battery equalization switch channel 14 and a negative battery equalization switch channel 15, and are totally 17 cables; the module management unit 2 is directly connected to a terminal from a battery, the voltage of each single battery is measured through a divider resistor, and the embedded microcontroller 4 reports the voltage to the main control board 3 through CAN communication; as shown in FIG. 4, the 32 MOSFET channels of the module management unit 2 are reversely arranged in pairs by using 64 80V low-resistance high-current MOSFETs, which are marked as channelsThe channels marked as odd numbers are used as negative battery equalization switch channels 15, the output ends of the channels marked as even numbers are connected with a second equalization bus 17 "-", the channels marked as even numbers are used as positive battery equalization switch channels 14, the output ends of the channels marked as even numbers are connected with a first equalization bus 16 "+", and when a certain battery such as Bi needs to be charged or discharged, the channels 2i and 2i-1 are simultaneously started; the terminals of the first equalizing bus 16 and the second equalizing bus 17 are connected with the equalizer 8; the embedded microcontroller 4 switches the charge-discharge mode of the equalizer 8; two-way Hall current sensors 50A-50A are arranged at the tail end of the second equalizing bus 17, equalizing current is measured, and closed-loop control is achieved through PID adjustment. The voltage acquisition unit 6 comprises a divider resistor, the divider resistor is connected between the input port of each single battery and the cathode of the first single battery in the battery module, and a voltage signal of each single battery is acquired by adopting a divider resistor sampling mode.
As shown in fig. 5, the total line resistance of the equalizer 8 and the capacity of the energy storage element 10 are main factors determining the equalization capability and the equalization current; q1 and Q2 of the equalization bus L1 are combined with the equalization bus L1, the first equalization bus 16 and the second equalization bus 17, Q6 and Q7 of the equalization bus L2 between the modules are both 600V super-junction MOSFETs, and the reversely arranged MOSFETs are connected in parallel through 3 components to reduce the on-resistance; the energy storage element 10 is a 400F super capacitor with a rated voltage of 2.7V, 2 super capacitors are used in series, the total rated voltage of 5.4V is more than 3.7V after series connection, and 4 super capacitors are needed in 2 groups of series energy storage elements; the charge-discharge mode switching switches Q3, Q4 and Q5 are formed by reverse arrangement in pairs by using 30V low-resistance large-current MOSFETs.
In this embodiment, the main control board 3 starts to implement inter-module balancing in a system standby state or a low-load operating state, and a schematic diagram of the balancing process is shown in fig. 6:
step 1, the main control board 3 compares the total voltage of the battery modules transmitted by each embedded microcontroller 4 to obtain the voltage difference value between the maximum voltage battery module BMi and the minimum voltage battery module BMj, and judges whether the voltage difference value is greater than the equilibrium starting voltage between the preset modules;
step 2, if the voltage difference value is larger than the balance starting voltage among the preset modules, entering a balance mode, in the Ui, sending a discharge instruction to the embedded microcontroller 4 by the main control board 3, starting the positive electrode battery balance switch channel 14 and the negative electrode battery balance switch channel 15 of the highest voltage single battery, starting Q1 and Q2, closing Q3, Q6 and Q7, enabling the C1 and the C2 to be in a parallel state, controlling the starting of the Q4 and the Q5 by adopting PWM signals, lasting for 20S-40S, respectively transferring the electric quantity of the highest voltage single battery to the C1 and the C2, then closing the Q1 and the Q2, and starting the Q6, the Q7 and the Q3;
step 3, in Uj, the main control board 3 sends a charging instruction to the embedded microcontroller 4 corresponding to Y, the embedded microcontroller 4 closes Q1, Q2 and Q3, opens Q4, Q5, Q6 and Q7, and adopts PWM signals to control Q3 for 20-40S;
and 4, in Uj, the main control board 3 sends a discharge instruction to the equalizer 8 to the embedded microcontroller 4, the embedded microcontroller 4 starts a positive battery equalization switch channel 14 and a negative battery equalization switch channel 15 of the single battery with the lowest voltage, starts Q1, Q2 and Q3, enables C1 and C2 to be connected in series to pull high voltage, closes Q4, Q5, Q6 and Q7, and controls Q3 by adopting a PWM signal for 20-40S.

Claims (4)

1. The utility model provides a modularization initiative equalizing battery management method, the management system who adopts includes main control board (3), a plurality of embedded microcontroller (4), M module management unit (2), every module management unit (2) include equalizer (8), N anodal battery equalizing switch passageway (14), N negative pole battery equalizing switch passageway (15), every equalizer (8) include first break-make change over switch (9-1), second break-make change over switch (9-2), two energy storage element (10) of establishing ties, fourth change over switch (11), second change over switch (12), third change over switch (13), its characterized in that, including following step:
step 1, the main control board (3) compares the total voltage of the battery modules transmitted by each embedded microcontroller (4) to obtain the voltage difference value between the maximum voltage battery module and the minimum voltage battery module, and judges whether the voltage difference value is greater than the balance starting voltage between preset modules or not, wherein a module management unit (2) corresponding to the maximum voltage battery module is marked as X, and a module management unit (2) corresponding to the minimum voltage battery module is marked as Y;
step 2, if the voltage difference value is larger than the balance starting voltage between the preset modules, the main control board (3) sends a discharge instruction to the embedded microcontroller (4) corresponding to the X, the embedded microcontroller (4) controls the single battery with the highest voltage to discharge, and the electric quantity is transferred to the equalizer (8) until the voltage of the equalizer (8) is balanced with the voltage of the single battery with the highest voltage;
step 3, the main control board (3) sends a charging instruction to the embedded microcontroller (4) corresponding to the Y, and the electric quantity is transferred from the equalizer (8) in the X to the equalizer (8) in the Y until the voltage of the equalizer (8) in the X and the voltage of the equalizer (8) in the Y are balanced;
and 4, the embedded microcontroller (4) corresponding to the Y sends a discharging instruction to the equalizer (8) of the embedded microcontroller, and the equalizer (8) transfers the electric quantity to the single battery with the lowest voltage, so that the voltage of the equalizer (8) and the voltage of the lowest single battery are balanced.
2. The method according to claim 1, wherein step 2 specifically comprises:
the method comprises the steps of starting a positive electrode battery balancing switch channel (14) and a negative electrode battery balancing switch channel (15) of a highest-voltage single battery, starting a first on-off switch (9-1), a second on-off switch (9-2) and two second switches (12), closing a fourth switch (11) and two third switches (13), respectively transferring the electric quantity of the highest-voltage single battery to two energy storage elements (10), closing the first on-off switch (9-1) and the second on-off switch (9-2) until the voltage of the two energy storage elements (10) is respectively balanced with the voltage of the highest-voltage single battery, and starting the fourth switch (11) and the two third switches (13).
3. The method according to claim 2, wherein step 3 specifically comprises:
and closing the first on-off change-over switch (9-1), the second on-off change-over switch (9-2) and the fourth change-over switch (11), and opening the two second change-over switches (12) and the two third change-over switches (13) until the total voltage of the two energy storage elements (10) in the X and the total voltage of the two energy storage elements (10) in the Y are balanced.
4. The method according to claim 3, wherein step 4 specifically comprises:
and opening a positive electrode battery balancing switch channel (14) and a negative electrode battery balancing switch channel (15) of the lowest voltage single battery, opening the first on-off switch (9-1), the second on-off switch (9-2) and the fourth switch (11), and closing the two second switches (12) and the two third switches (13) to balance the total voltage of the two energy storage elements (10) with the electric quantity of the single battery.
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