CN104795857A - Lithium ion battery energy balance system and implementation method thereof - Google Patents

Lithium ion battery energy balance system and implementation method thereof Download PDF

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Publication number
CN104795857A
CN104795857A CN201510128269.2A CN201510128269A CN104795857A CN 104795857 A CN104795857 A CN 104795857A CN 201510128269 A CN201510128269 A CN 201510128269A CN 104795857 A CN104795857 A CN 104795857A
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ion battery
lithium ion
lithium
battery
voltage
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CN201510128269.2A
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CN104795857B (en
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付宇卓
李维嘉
刘婷
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上海交通大学
上海紫竹新兴产业技术研究院
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Abstract

The invention discloses a lithium ion battery energy balance system and an implementation method thereof, the system comprises a lithium ion battery pack, n voltage detection circuits, n DCDC converters, n main control chips, a data processing chip, a CAN communication module and a current detection circuit, the lithium ion battery pack consists of n single lithium ion batteries which are connected in series, the input end of the Kth voltage detection circuit is connected with the positive electrode and negative electrode of the kth single lithium ion battery, sampling is started when voltage detection requires conducting, the sampling value is isolated and then transmitted to the kth set of main control chips, each DCDC converter directly carries out charging and discharging to each single lithium ion battery in the lithium ion battery pack respectively through controlling the switch of an MOS pipe, simultaneously, the balanced current is adjusted through switching frequency, the lithium ion battery energy balance system and the implementation method thereof use a second-order RC model to simulate a lithium ion battery chemistry model, and uses the SOC generated by linear regression as the judging basis of lithium ion battery equalization, thereby achieving the equalization purpose.

Description

Lithium ion battery balancing energy system and its implementation
Technical field
The present invention relates to a kind of lithium ion battery balancing energy system and its implementation, particularly relate to a kind of lithium ion battery balancing energy system based on battery SoC and its implementation.
Background technology
The key of pure electric automobile development is battery.There is the performance significantly improving lithium battery in the batteries such as in recent years, lithium battery technology has had huge progress, LiFePO4, LiMn2O4, cobalt acid lithium; But the natural ubiquity of the inconsistency in lithium battery group between cell.The parameters of lithium battery inevitably produces some small differences in large-scale production process, and main manifestations is that lithium battery internal resistance, capacity, open circuit voltage etc. are inconsistent.Along with lithium battery access times increase, the impact of the larger temperature difference in long-time self discharge and automobile, these differences will be increasing, thus between the battery of lithium battery group, performance difference is increasing.And overcharge and cross to put and all can cause expendable infringement to battery, simultaneously again because the capacity of series battery determines by organizing interior minimum cell capacity, so once there is deep discharge or overcharge in certain battery in battery pack, whole battery pack must stop original charging and discharging state, otherwise battery life meeting deep fades, even can cause larger potential safety hazard.The most extreme situation is exactly, and lithium battery group partial monosomy battery is full of, and partial monosomy battery discharges, and at this time, whole battery pack both cannot have been charged and also cannot have been discharged.
The equalization function of lithium ion battery balanced management system mainly solves the inconsistency in lithium battery group, reduces the difference between battery, for extending battery life, reduces costs and is significant, and also can increase discharge capacity simultaneously.Current equalization methods is active equalization and passive equilibrium mainly, and balanced judgment criterion is divided into electric voltage equalization and SOC balance.Fundamentally say, battery balanced is the electric quantity balancing stored between each cell in battery pack, and magnitude of voltage is an external characteristic of battery, can not reflect battery SOC, therefore can not be very effective as the equalization methods differentiated according to voltage.Therefore, the SOC how obtaining lithium ion battery becomes the crucial part of equalizing system one, the difficult problem that one, the Ye Shi world is important simultaneously.How controlling equalizing circuit is also a comparatively complicated problem, due to the characteristic of the nonlinearity of lithium ion battery, so neither one Mathematical Modeling comparatively accurately.Determine so control strategy is also more difficult, as the factor of input and output, how effectively to control.
Summary of the invention
For overcoming the deficiency that above-mentioned prior art exists, the object of the present invention is to provide a kind of lithium ion battery balancing energy system and its implementation, by the estimation of the SOC of lithium ion battery in the process of balancing energy transfer, with this SOC for balanced according to being realized by control DCDC, the mistake that the mode making system avoid electric voltage equalization causes is balanced, and reliability is higher.
For reaching above-mentioned and other object, the present invention proposes a kind of lithium ion battery balancing energy system, comprising:
Li-ion batteries piles, described Li-ion batteries piles is composed in series by n block lithium-ion battery monomer, and each lithium-ion battery monomer connects a voltage detecting circuit and a DC-DC converter;
N voltage detecting circuit, the input of a kth voltage detecting circuit connects positive pole and the negative pole of a kth lithium-ion battery monomer respectively, and when needs carry out voltage detecting, start sampling, and its sampled value is transferred into kth group main control chip after isolation;
N DC-DC converter, each DC-DC converter, by controlling the switch of metal-oxide-semiconductor, directly carries out charging and discharging to lithium-ion battery monomer each in Li-ion batteries piles respectively, simultaneously by switching frequency adjustment electric current;
N main control chip, each main control chip reads the information of voltage of lithium ion battery in voltage detecting circuit corresponding to each lithium-ion battery monomer, is then delivered in data processing chip 60 by data by CAN;
Data processing chip, the SOC of each lithium-ion battery monomer is calculated by the method for linear regression, determine whether equilibrium is carried out to Li-ion batteries piles according to FUZZY ALGORITHMS FOR CONTROL simultaneously, equalizing signal is sent to each main control chip through CAN communication module by data processing chip 60, and enable for equilibrium control signal sends to each lithium-ion battery monomer to carry out Balance route by each main control chip;
CAN communication module, is responsible for the communication realizing described main control chip and described data processing chip;
Current detection circuit, connects described Li-ion batteries piles and data processing chip, for detecting the euqalizing current of battery pack to open or to turn off the switching tube of primary and secondary.
Further, described DC-DC converter adopts bi-directional synchronization inverse-excitation type DC-DC converter, and each DC-DC converter other DCDC all independent, one end of each DC-DC converter connects lithium-ion battery monomer, and the other end connects Li-ion batteries piles.
Further, a kth bi-directional synchronization inverse-excitation type DCD transducer comprises high frequency transformer (Tk), primary switch pipe (Qkp), secondary switch pipe (Qks), the source electrode of primary switch pipe (Qkp) is connected to the negative pole of lithium-ion battery monomer (Cellk), the drain electrode of primary switch pipe (Qkp) is connected to elementary one end of high frequency transformer (Tk), the elementary other end of high frequency transformer (Tk) is connected to the positive pole of lithium-ion battery monomer (Cellk), the source electrode of secondary switch pipe (Qks) is connected to the negative pole of this Li-ion batteries piles, the drain electrode of secondary switch pipe (Qks) is connected to secondary one end of high frequency transformer (Tk), the secondary other end of high frequency transformer (Tk) is connected to the positive pole of Li-ion batteries piles.
For achieving the above object, the present invention also provides a kind of implementation method of lithium ion battery balancing energy, comprises the steps:
Step one, the information of every block cell voltage and electric current in multi collect Li-ion batteries piles;
Step 2, is input in data processing chip by the nonlinear curve relation information of the information of the voltage and current of every block battery and battery capacity, life-span, open circuit voltage and SOC;
Step 3, repeatedly measured battery voltage signal is carried out discretization according to the Order RC model of battery, and by the method for linear regression, data are processed, draw useful matrix information, and calculate the open circuit voltage corresponding to lithium ion battery by matrix;
Step 4, according to the open circuit voltage of calculated battery, is gone out the SOC of lithium ion battery, and calculates the average SOC of battery pack by the open circuit voltage of lithium ion battery and SOC relation curve interpolation;
Step 5, according to the method for fuzzy control, judges the euqalizing current required for battery and time for balance by the SOC of calculated lithium ion battery;
Step 6, controls two-way inverse-excitation type DC-DC converter, and reach certain peak value by the electric current detected on DCDC, the switch MOS pipe controlling two-way inverse-excitation type DCDC realizes the break-make of the electric current in Li-ion batteries piles, thus realizes lithium ion battery energy trasfer.
Further, after step 4, also comprise the steps:
Calculate the battery decentralization of Li-ion batteries piles;
Judge whether battery decentralization is greater than predetermined threshold;
If when battery decentralization is less than this predetermined threshold, then enters step one and continue to press off the beginning from detection lithium ion battery battery; If when lithium ion battery decentralization is greater than this predetermined threshold, then enter step 5.
Further, in step one, extract frequency to the cell voltage of lithium ion battery and current information higher, the voltage and current information interval time is shorter.
Further, step 3 comprises the steps:.
According to repeatedly measured electric current and voltage information by obtaining the estimation to SOC to the Order RC model discretization of lithium ion battery;
By Li-ion battery model, using the electric current by model as excitation I, the terminal voltage of lithium ion battery and the difference of open circuit voltage responsively, draw the transfer function of model;
When sample frequency is very high time, this transfer function Bilinear transformation method is carried out discretization, draws difference equation, difference is converted to the value of terminal voltage and open circuit voltage simultaneously.
Further, in step 4, according to the information matrix that step 3 calculates, by the open-circuit voltage values of lithium ion battery, the open circuit voltage stored according to step 2 and SOC curved line relation, pass through curve chart, and utilizing the open-circuit voltage values calculated, interpolation draws lithium ion battery SOC now.
Further, in step 5, control this two-way inverse-excitation type DC-DC converter, a lithium-ion battery monomer of ining succession, in succession the Li-ion batteries piles that lithium ion that polylith lithium ion battery links up is formed in other end, the transfer realizing lithium ion battery energy is cut-off by metal-oxide-semiconductor, and measure by the precision resistance on coil the electric current that lithium ion battery shifts, realize the Current Control for lithium ion battery energy trasfer, pass through time controling simultaneously, realize the length of the time of lithium ion battery energy trasfer, by the length to switching frequency and time, realize the size of current of lithium ion battery and the control of time.
Further, the time controlling lithium ion battery energy trasfer is determined by fuzzy controller, and this fuzzy controller is single argument two-dimensional fuzzy controller.
Compared with prior art, a kind of lithium ion battery balancing energy system of the present invention and its implementation, by the estimation of the SOC of lithium ion battery in the process of balancing energy transfer, with this SOC for balanced according to being realized by control DCDC, the mistake that the mode making system avoid electric voltage equalization causes is balanced, and reliability is higher.
Accompanying drawing explanation
Fig. 1 is the system construction drawing of a kind of lithium ion battery balancing energy of the present invention system;
Fig. 2 is the structural representation of bi-directional synchronization inverse-excitation type DC-DC converter in present pre-ferred embodiments;
Fig. 3 is the flow chart of steps of the implementation method of a kind of lithium ion battery balancing energy of the present invention;
Fig. 4 is the Order RC model discretization schematic diagram to lithium ion battery in present pre-ferred embodiments;
The curve chart that Fig. 5 utilizes for the SOC calculating lithium ion battery in present pre-ferred embodiments;
Fig. 6 is the triangle membership function schematic diagram in present pre-ferred embodiments selected by fuzzy controller;
Fig. 7 is the flow chart of the specific embodiment of the implementation method of a kind of lithium ion battery balancing energy of the present invention.
Embodiment
Below by way of specific instantiation and accompanying drawings embodiments of the present invention, those skilled in the art can understand other advantage of the present invention and effect easily by content disclosed in the present specification.The present invention is also implemented by other different instantiation or is applied, and the every details in this specification also can based on different viewpoints and application, carries out various modification and change not deviating under spirit of the present invention.
Fig. 1 is the system construction drawing of a kind of lithium ion battery balancing energy of the present invention system.As shown in Figure 1, a kind of lithium ion battery balancing energy of the present invention system, comprising: Li-ion batteries piles 10, a n voltage detecting circuit 20, a n DC-DC converter 30, a n main control chip 40, current detection circuit 50, data processing chip 60 and CAN communication module
Li-ion batteries piles 10 is by n block lithium-ion battery monomer (Cell1, Cell2, Celln) be composed in series, each lithium-ion battery monomer connects a voltage detecting circuit 20, voltage detecting circuit 20 often saves the voltage of lithium-ion battery monomer in Li-ion batteries piles for gathering, and sampled value is sent to each main control chip 40, namely the input of a kth voltage detecting circuit 20 connects positive pole and the negative pole of a kth lithium-ion battery monomer respectively, and when needs carry out voltage detecting, starting sampling, its sampled value is transferred into kth group main control chip after isolation; Each lithium-ion battery monomer also connects a DC-DC converter 30, each DC-DC converter 30 is by controlling the switch of metal-oxide-semiconductor, directly charging and discharging can be carried out respectively to lithium-ion battery monomer each in Li-ion batteries piles, simultaneously by switching frequency adjustment electric current, each DC-DC converter other DCDC all independent, one end of each DC-DC converter connects lithium-ion battery monomer, and the other end connects Li-ion batteries piles.
In present pre-ferred embodiments, DC-DC converter 30 have employed bi-directional synchronization inverse-excitation type DC-DC converter.Fig. 2 is the structural representation of bi-directional synchronization inverse-excitation type DC-DC converter in present pre-ferred embodiments.Specifically, a kth bi-directional synchronization inverse-excitation type DCDC comprises high frequency transformer Tk, primary switch pipe Qkp, secondary switch pipe Qks, the source electrode of primary switch pipe Qkp is connected to the negative pole of lithium-ion battery monomer Cellk, the drain electrode of primary switch pipe Qkp is connected to elementary one end of high frequency transformer Tk, the elementary other end of high frequency transformer Tk is connected to the positive pole of lithium-ion battery monomer Cellk, the source electrode of secondary switch pipe Qks is connected to the negative pole of Li-ion batteries piles, the drain electrode of secondary switch pipe Qks is connected to secondary one end of high frequency transformer Tk, the secondary other end of high frequency transformer Tk is connected to the positive pole of Li-ion batteries piles.
To give first piece of lithium-ion electric tank discharge, when conducting primary switch, electric current (being calculated the electric current of the winding passed through by the potentiometer measured on winding) in DCDC armature winding, slope is risen, until when electric current is greater than average current 2 times.Primary switch turns off subsequently, and the energy be stored in DCDC is transferred to secondary winding, thus causes electric current to flow in the secondary winding of DCDC.Secondary switch is connected being stored in the energy trasfer of secondary winding in DCDC in Li-ion batteries piles, till the electric current by winding reduces to 0A.Be zero once secondary current, then secondary switch disconnects and primary switch recloses, thus repeats described circulation just now.Move in circles, energy will be transferred to all Li-ion batteries piles be connected between secondary winding top and bottom from lithium-ion battery monomer, thus charges to Li-ion batteries piles.
Main control chip 40 reads the information of voltage of lithium ion battery in voltage checking chip corresponding to each lithium-ion battery monomer, then data are delivered in data processing chip 60 by CAN, data processing chip 60 calculates SOC (the State of Charge of each lithium-ion battery monomer by the method for linear regression, state-of-charge), determine whether equilibrium is carried out to Li-ion batteries piles according to FUZZY ALGORITHMS FOR CONTROL simultaneously, how balanced data processing chip 60 send to each main control chip 40 by the need of the signal of equilibrium and signal through CAN communication module 70, enable for equilibrium control signal sends to each lithium-ion battery monomer to carry out Balance route by each main control chip 40, thus the lithium-ion battery monomer lower to SOC carries out charge balancing, the lithium-ion battery monomer higher to SOC carries out equalization discharge, CAN communication module primary responsibility realizes the communication of main control chip 40 and data processing chip 60, current detection circuit 50 connects Li-ion batteries piles 10 and data processing chip 60, for detecting the euqalizing current of battery pack to open or to turn off the switching tube of primary and secondary.
Fig. 3 is the flow chart of steps of the implementation method of a kind of lithium ion battery balancing energy of the present invention.As shown in Figure 3, the implementation method of a kind of lithium ion battery balancing energy of the present invention, comprises the steps:
Step 301, the information of every block cell voltage and electric current in multi collect Li-ion batteries piles.Preferably, extract frequency to the cell voltage of lithium ion battery and current information higher, the voltage and current information interval time is shorter, as 100Hz.
Step 302, is input to information such as the nonlinear curve relations of the information of the voltage and current of every block battery and battery capacity, life-span, open circuit voltage and SOC in data processing chip.Preferably, the voltage and current information of the lithium ion battery repeatedly recorded is input in data processing chip, and with in advance stored in data relevant with battery information (relation as open circuit voltage and SOC) read open circuit voltage more afterwards.
Step 303, repeatedly measured battery voltage signal is carried out discretization according to the Order RC model of battery, and by the method for linear regression, data are processed, draw useful matrix information, and calculate other information etc. corresponding to lithium ion battery by matrix, the most importantly open circuit voltage of lithium ion battery.
Specifically, step 303 comprises:
First, according to repeatedly measured electric current and voltage information by obtaining the estimation to SOC to the Order RC model discretization of lithium ion battery, as shown in Figure 4.
Then by Li-ion battery model, will by the electric current of model as excitation I, responsively, then at this moment lithium ion battery can as a transfer function for the terminal voltage of lithium ion battery and the difference of open circuit voltage:
E ( s ) = I ( s ) R Ω + I ( s ) ( R 1 / / 1 s C 1 ) + I ( s ) ( R 2 / / 1 s C 2 )
Wherein, E is battery lithium ions terminal circuit and difference in open circuit voltage, and I is the electric current by winding, R Ωfor Ohmic resistance, R 1, R 2, C 1, C 2for the resistance capacitance of Order RC in model.
Show that the transfer function of model is:
G ( s ) = E ( s ) I ( s ) = R Ω + R 1 1 + R 1 C 1 s + R 2 1 + R 2 C 2 s
Wherein, E is battery lithium ions terminal circuit and difference in open circuit voltage, and I is the electric current by battery, R Ωfor Ohmic resistance, R 1, R 2, C 1, C 2for the resistance capacitance of Order RC in model
When sample frequency is very high time, above-mentioned transfer function Bilinear transformation method is carried out discretization, draws difference equation:
E(k)=a 1E(k-1)+a 2E(k-2)+a 3I(k)+a 4I(k-1)+a 5I(k-2)
E is battery lithium ions terminal circuit and difference in open circuit voltage, and I is the electric current by battery, and a1, a2, a3, a4, a5 are the coefficient after discretization.
Difference is converted to the value of terminal voltage and open circuit voltage, because the sampling time is very fast, open circuit voltage is similar to, and can obtain simultaneously:
V(k)=θ 1V(k-1)+θ 2V(k-2)+θ 3I(k)+θ 4I(k-1)+θ 5I(k-2)+θ 6
Order:
θ = θ 1 θ 2 θ 3 θ 4 θ 5 θ 6 T
X ( k ) = V ( k - 1 ) V ( k - 2 ) I ( k ) I ( k - 1 ) I ( k - 2 ) 1
Then above formula can be write as the form of matrices multiplication:
V(k)=X T(k)θ
Above-mentioned θ = θ 1 θ 2 θ 3 θ 4 θ 5 θ 6 T Asking for due to the form for matrices multiplication of value, calculates matrix by multiple linear regression method, even for Y=XZ, then and Z=(X tx) -1x ty.
After calculating information matrix by linear regression, and by the calculating of formula, mainly calculate the open circuit voltage OCV of lithium ion battery, draw other information of lithium ion battery simultaneously:
OCV(k)=θ 6/[1-(a 1+a 2)+a 1a 2]=θ 6/(1-θ 12)
a 1 = ( θ 1 + θ 1 2 + 4 θ 2 ) / 2
a 2 = ( θ 1 - θ 1 2 + 4 θ 2 ) / 2
b 1 = ( θ 3 a 1 2 + θ 4 a 1 + θ 5 ) / ( a 1 - a 2 )
b 2 = ( θ 3 a 2 2 + θ 4 a 2 + θ 5 ) / ( a 1 - a 2 )
R Ω=-θ 3
R 1=b 1/(1-a 1)
C 1=-T/(R 1lna 1)
R 2=b 2/(1-a 2)
Wherein, OCV is open circuit voltage, θ 16for just now returning the value of required θ matrix, a1, a2, a3, a4, a5 were the coefficient after discretization, R Ωfor Ohmic resistance, R 1, R 2, C 1, C 2for the resistance capacitance of Order RC in model.
Step 304, according to the open circuit voltage of calculated battery, is gone out the SOC of lithium ion battery, and calculates the average SOC of battery pack by the open circuit voltage of lithium ion battery and SOC relation curve interpolation.
Specifically, according to the information matrix that step 303 calculates, by the open-circuit voltage values of lithium ion battery, the open circuit voltage stored according to step 302 and SOC curved line relation, by curve chart as shown in Figure 5, utilize the open-circuit voltage values calculated, interpolation can draw lithium ion battery SOC now.
Step 305, controls two-way inverse-excitation type DC-DC converter, and reach certain peak value by the electric current detected on DCDC, the switch MOS pipe controlling two-way inverse-excitation type DCDC realizes the break-make of the electric current in Li-ion batteries piles, thus realizes lithium ion battery energy trasfer.
Specifically, control two-way inverse-excitation type DC-DC converter, a lithium-ion battery monomer of ining succession, in succession the Li-ion batteries piles that lithium ion that polylith lithium ion battery links up is formed in other end, the transfer realizing lithium ion battery energy is cut-off by metal-oxide-semiconductor, and measure by the precision resistance on coil the electric current that lithium ion battery shifts, realize the Current Control for lithium ion battery energy trasfer, pass through time controling simultaneously, realize the length of the time of lithium ion battery energy trasfer, by the length to switching frequency and time, realize the size of current of lithium ion battery and the control of time.
Step 306, method according to fuzzy control, the SOC of calculated lithium ion battery is judged the euqalizing current required for battery and time for balance, the balanced lithium ion battery of balanced DCDC is controlled until battery balanced finally complete finally by step 305, the sample difference of the battery of namely all lithium ion batteries is less than 2%, otherwise continues from step 301.
The time controlling lithium ion battery energy trasfer is determined primarily of fuzzy control, and fuzzy controller used in the present invention is single argument two-dimensional fuzzy controller, i.e. two inputs output.The input of fuzzy controller needs the relation condition that accurately can reflect the battery of battery pack and required equilibrium, therefore, the average SOC being input as the difference battery pack of the SOC of the average SOC of battery pack and required balancing battery of fuzzy controller selected according to reality is as input.Larger difference means the object that the longer time for balance of needs reaches balanced, otherwise time less then.When average SOC is close to charge or discharge state, then time for balance is long, to reach the effect of fast uniform, prevents over-charging of battery from crossing and puts, when average SOC is in intermediateness, then and can be balanced to reach balanced better effect at a slow speed.By the fuzzy control knowledge base shown in following table 1, select triangle as the shape (as shown in Figure 6) of membership function, the output of fuzzy controller is control time for balance T in equalizing circuit and euqalizing current I, and the switching time controlling DC-DC converter reaches control portfolio effect.
Table 1 fuzzy control knowledge base
Fig. 7 is the flow chart of the specific embodiment of the implementation method of a kind of lithium ion battery balancing energy of the present invention.As shown in Figure 7, the present invention, by carrying out discharge and recharge to lithium ion battery, gathers voltage, the electric current of lithium ion battery.The voltage characteristic of research lithium ion battery and SOC characteristic.Comprise the relation curve of OCV (open circuit voltage) and SOC, the relation curve of the internal resistance of battery and the SOC of battery, observe performance of lithium ion battery curve.Then lithium ion battery electric current and voltage data are imported in data processing plate.By the difference equation of Order RC model, calculate lithium ion battery open circuit voltage at that time by equation of linear regression, and calculate lithium ion battery SOC at that time by interpolation method.Then the average SOC of Li-ion batteries piles is calculated.Calculate the battery decentralization of Li-ion batteries piles, judge whether battery decentralization is greater than 2%.If when battery decentralization is less than 2%, continue to press off the beginning from detection lithium ion battery battery.If when lithium ion battery decentralization is greater than 2%, then judge euqalizing current and time for balance by fuzzy control.After the euqalizing current drawing Li-ion batteries piles and time for balance, by controlling DC-DC converter, lithium ion battery equilibrium is controlled, until battery decentralization is less than 2%.
In sum, a kind of lithium ion battery balancing energy system of the present invention and its implementation, by the estimation of the SOC of lithium ion battery in the process of balancing energy transfer, with this SOC for balanced according to being realized by control DCDC, the mistake that the mode making system avoid electric voltage equalization causes is balanced, and reliability is higher.
Above-described embodiment is illustrative principle of the present invention and effect thereof only, but not for limiting the present invention.Any those skilled in the art all without prejudice under spirit of the present invention and category, can carry out modifying to above-described embodiment and change.Therefore, the scope of the present invention, should listed by claims.

Claims (10)

1. a lithium ion battery balancing energy system, comprising:
Li-ion batteries piles, described Li-ion batteries piles is composed in series by n block lithium-ion battery monomer, and each lithium-ion battery monomer connects a voltage detecting circuit and a DC-DC converter;
N voltage detecting circuit, the input of a kth voltage detecting circuit connects positive pole and the negative pole of a kth lithium-ion battery monomer respectively, and when needs carry out voltage detecting, start sampling, and its sampled value is transferred into kth group main control chip after isolation;
N DC-DC converter, each DC-DC converter, by controlling the switch of metal-oxide-semiconductor, directly carries out charging and discharging to lithium-ion battery monomer each in Li-ion batteries piles respectively, simultaneously by switching frequency adjustment electric current;
N main control chip, each main control chip reads the information of voltage of lithium ion battery in voltage detecting circuit corresponding to each lithium-ion battery monomer, is then delivered in data processing chip 60 by data by CAN;
Data processing chip, the SOC of each lithium-ion battery monomer is calculated by the method for linear regression, determine whether equilibrium is carried out to Li-ion batteries piles according to FUZZY ALGORITHMS FOR CONTROL simultaneously, equalizing signal is sent to each main control chip through CAN communication module by data processing chip 60, and enable for equilibrium control signal sends to each lithium-ion battery monomer to carry out Balance route by each main control chip;
CAN communication module, is responsible for the communication realizing described main control chip and described data processing chip;
Current detection circuit, connects described Li-ion batteries piles and data processing chip, for detecting the euqalizing current of battery pack to open or to turn off the switching tube of primary and secondary.
2. a kind of lithium ion battery balancing energy system as claimed in claim 1, it is characterized in that: described DC-DC converter adopts bi-directional synchronization inverse-excitation type DC-DC converter, each DC-DC converter other DCDC all independent, one end of each DC-DC converter connects lithium-ion battery monomer, and the other end connects Li-ion batteries piles.
3. a kind of lithium ion battery balancing energy system as claimed in claim 2, it is characterized in that: a kth bi-directional synchronization inverse-excitation type DCD transducer comprises high frequency transformer (Tk), primary switch pipe (Qkp), secondary switch pipe (Qks), the source electrode of primary switch pipe (Qkp) is connected to the negative pole of lithium-ion battery monomer (Cellk), the drain electrode of primary switch pipe (Qkp) is connected to elementary one end of high frequency transformer (Tk), the elementary other end of high frequency transformer (Tk) is connected to the positive pole of lithium-ion battery monomer (Cellk), the source electrode of secondary switch pipe (Qks) is connected to the negative pole of this Li-ion batteries piles, the drain electrode of secondary switch pipe (Qks) is connected to secondary one end of high frequency transformer (Tk), the secondary other end of high frequency transformer (Tk) is connected to the positive pole of Li-ion batteries piles.
4. an implementation method for lithium ion battery balancing energy, comprises the steps:
Step one, the information of every block cell voltage and electric current in multi collect Li-ion batteries piles;
Step 2, is input in data processing chip by the nonlinear curve relation information of the information of the voltage and current of every block battery and battery capacity, life-span, open circuit voltage and SOC;
Step 3, repeatedly measured battery voltage signal is carried out discretization according to the Order RC model of battery, and by the method for linear regression, data are processed, draw useful matrix information, and calculate the open circuit voltage corresponding to lithium ion battery by matrix;
Step 4, according to the open circuit voltage of calculated battery, is gone out the SOC of lithium ion battery, and calculates the average SOC of battery pack by the open circuit voltage of lithium ion battery and SOC relation curve interpolation;
Step 5, according to the method for fuzzy control, judges the euqalizing current required for battery and time for balance by the SOC of calculated lithium ion battery;
Step 6, controls two-way inverse-excitation type DC-DC converter, and reach certain peak value by the electric current detected on DCDC, the switch MOS pipe controlling two-way inverse-excitation type DCDC realizes the break-make of the electric current in Li-ion batteries piles, thus realizes lithium ion battery energy trasfer.
5. the implementation method of a kind of lithium ion battery balancing energy as claimed in claim 4, is characterized in that, after step 4, also comprise the steps:
Calculate the battery decentralization of Li-ion batteries piles;
Judge whether battery decentralization is greater than predetermined threshold;
If when battery decentralization is less than this predetermined threshold, then enters step one and continue to press off the beginning from detection lithium ion battery battery; If when lithium ion battery decentralization is greater than this predetermined threshold, then enter step 5.
6. the implementation method of a kind of lithium ion battery balancing energy as claimed in claim 5, is characterized in that: in step one, and extract frequency to the cell voltage of lithium ion battery and current information higher, the voltage and current information interval time is shorter.
7. the implementation method of a kind of lithium ion battery balancing energy as claimed in claim 6, it is characterized in that, step 3 comprises the steps:.
According to repeatedly measured electric current and voltage information by obtaining the estimation to SOC to the Order RC model discretization of lithium ion battery;
By Li-ion battery model, using the electric current by model as excitation I, the terminal voltage of lithium ion battery and the difference of open circuit voltage responsively, draw the transfer function of model;
When sample frequency is very high time, this transfer function Bilinear transformation method is carried out discretization, draws difference equation, difference is converted to the value of terminal voltage and open circuit voltage simultaneously.
8. the implementation method of a kind of lithium ion battery balancing energy as claimed in claim 6, it is characterized in that: in step 4, according to the information matrix that step 3 calculates, by the open-circuit voltage values of lithium ion battery, the open circuit voltage stored according to step 2 and SOC curved line relation, by curve chart, and utilize the open-circuit voltage values calculated, interpolation draws lithium ion battery SOC now.
9. the implementation method of a kind of lithium ion battery balancing energy as claimed in claim 6, it is characterized in that: in step 5, control this two-way inverse-excitation type DC-DC converter, a lithium-ion battery monomer of ining succession, in succession the Li-ion batteries piles that lithium ion that polylith lithium ion battery links up is formed in other end, the transfer realizing lithium ion battery energy is cut-off by metal-oxide-semiconductor, and measure by the precision resistance on coil the electric current that lithium ion battery shifts, realize the Current Control for lithium ion battery energy trasfer, pass through time controling simultaneously, realize the length of the time of lithium ion battery energy trasfer, by the length to switching frequency and time, realize the size of current of lithium ion battery and the control of time.
10. the implementation method of a kind of lithium ion battery balancing energy as claimed in claim 9, is characterized in that: the time controlling lithium ion battery energy trasfer is determined by fuzzy controller, and this fuzzy controller is single argument two-dimensional fuzzy controller.
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