CN105449739B - State of charge of series-connected batteries SOC On-line Estimation method based on single battery - Google Patents

Abstract

The state of charge of series-connected batteries SOC On-line Estimation method based on single battery that the invention discloses a kind of, comprising the following steps: central controller sending time benchmark and soft synchronized sampling time interval give all local controllers；Central controller sample rate current and logging timestamp；Voltage, temperature and the logging timestamp of each local controller sampling single battery；It is soft synchronous that timestamp is carried out to the voltage of each single battery, electric current and temperature after each local controller；Each each single battery parameter of local controller recursion on-line identification；Each each single battery SOC of local controller ART network；The state-of-charge SOC of central controller calculating series-connected cell group.The present invention realizes the On-line Estimation to the state-of-charge SOC of single battery each in series-connected cell group and the series-connected cell group SOC On-line Estimation based on this, has the characteristics that SOC estimated accuracy is high, adaptive in its life cycle management to the different use environment conditions of series-connected cell group, operating condition.

Description

State of charge of series-connected batteries SOC On-line Estimation method based on single battery

Technical field

The present invention relates to battery management system technology, specifically a kind of state of charge of series-connected batteries based on single battery SOC On-line Estimation method.

Background technique

State-of-charge SOC is used to characterize the remaining capacity of battery, is evaluation remaining battery ability, rationally fully using electricity Pond and the important parameter for avoiding abuse battery, for electric car, the reliable estimation of high-precision SOC is even more to solve electric car The important foundation of mileage anxiety problem.To meet the high-power and big energy storage capacity requirement such as electric car to battery, need list Body battery is used in series.

There are many factor for influencing SOC estimated accuracy, including use environment condition, applying working condition condition and inside battery Electrochemical effect etc. is not directly on-line measurement, can only utilize the sensors such as collected cell voltage, electric current and temperature Signal is estimated.Currently, the On-line Estimation method of SOC mainly have current integration method, Kalman filtering method, neural network, Fuzzy logic method etc. there is a problem of not low towards battery life cycle and estimated accuracy very well.Especially to series-connected cell group For, it theoretically should be using the SOC of SOC in battery pack minimum single battery as the SOC of battery pack.But existing series-connected cell Group SOC estimation method, due to consideration that cost and the complexity of battery management system etc., are not able to achieve to single in series-connected cell group The On-line Estimation of the SOC of body battery, to make the SOC of the estimated series-connected cell group come out and the practical SOC of series-connected cell group There are biggish error, leads to that the practical charging and discharging capabilities of series-connected cell group are failed rationally fully to utilize, cause to electricity The waste of pond group ability；Or there is the risk of abuse battery caused by battery pack to be made full use of.

Summary of the invention

For the defects in the prior art, the present invention provides a kind of state of charge of series-connected batteries based on single battery SOC On-line Estimation method.

The purpose of the present invention is achieved through the following technical solutions: a kind of series-connected batteries shape based on single battery State SOC On-line Estimation method, which comprises the steps of:

Step 1, central controller BCU send sample start times benchmark TB and soft synchronized sampling time interval △ t to institute There is local controller BMU；

Step 2, central controller BCU since TB, carried out at interval of △ t to by the electric current of the series-connected cell group It samples, and the current sequence I of series-connected cell group will be passed through_NIAnd its timestamp n of corresponding sampling_NIIt is sent by CAN bus To each local controller BMU, wherein n_NIFor I_NIThe number of △ t between sampling instant and TB, subscript NI are to sample resulting lead to Cross the serial number of the current value of series-connected cell group；

Step 3, each local controller BMU are since TB, at interval of △ t by its synchronized sampling holding circuit to series electrical The voltage of the corresponding single battery of its in the group of pond, temperature are sampled, and the voltage V of single battery is obtained_{I, j} ^NC, temperature T_{I, j} ^NC, Record each V_{I, j} ^NC、T_{I, j} ^NCThe number n of △ t between sampling instant and TB_{I, j} ^NCAs V_{I, j} ^NC、T_{I, j} ^NCThe timestamp of sampling, In, subscript i is the number of local controller BMU, subscript j is single battery corresponding to i-th of local controller BMU volume Number, subscript NC is the voltage value for sampling resulting single battery, the serial number of temperature value；

Step 4, each local controller BMU receive the current value I from central controller BCU by CAN bus_NIAnd its phase The n answered_NI, by n_{I, j} ^NC=n_NIThe voltage V of corresponding single battery_{I, j} ^NC, temperature T_{I, j} ^NCWith I_NICombo, to obtain based on the time The voltage Vs of the single battery of synchronization after stabbing soft synchronize_{I, j}, electric current Is_{I, j}With temperature Ts_{I, j}；

Step 5, each local controller use the voltage Vs of each single battery respectively_{I, j}, electric current Is_{I, j}With temperature Ts_{I, j}, hold Row is based on each single battery parameter in battery equivalent circuit model and to being not covered by battery effect in battery equivalent circuit model Carry out the recursion on-line identification of each single battery parameter of comprehensive simulation；

Step 6, each local controller execute the adaptive state-of-charge SOC estimation method of both-end self-correcting, obtain each monomer The state-of-charge SOC of battery_{I, j}, and by SOC_{I, j}Central controller BCU is sent to by CAN bus；

Step 7, central controller BCU are calculated by the following formula the state-of-charge SOC of series-connected cell group^BP

SOC^BP=min [SOC_{I, j},

In formula, the number of i=1- local controller BMU, single battery corresponding to i-th of local controller BMU of j=1- Number.

Each local controller in the step 5 uses the voltage Vs of each single battery respectively_{I, j}, electric current Is_{I, j}And temperature Ts_{I, j}, execute based on each single battery parameter in battery equivalent circuit model and to being not covered by electricity in battery equivalent circuit model Pond effect carries out the recursion on-line identification of each single battery parameter of comprehensive simulation, and the battery equivalent circuit model is Thevenin model, each single battery parameter in the battery equivalent circuit model include the open-circuit voltage of single battery V_{Oc, i, j}, single battery DC internal resistance R_{In, i, j}, charge transfer phenomenon for simulating single battery the circuit RC in resistance R_{P, i, j}With capacitor C_{P, i, j}, the monomer electricity that battery effect carries out comprehensive simulation is not covered by moment k, battery equivalent circuit model Pond parameter is the coloured noise added as constructed by the sliding average of white noise in the output end of battery equivalent circuit model W_{K, i, j}。

The method of the recursion on-line identification is recursion extended least squares method, to each single battery (i, j, i=1- sheet The number of ground controller BMU, the number of single battery corresponding to i-th of local controller BMU of j=1-), it clocks when carving k The Vs of single battery (i, j)_{I, j}, electric current Is_{I, j}With temperature Ts_{I, j}Respectively V_{T, k}、I_k、T_k, specifically comprise the following steps:

Step 501 presses formula Γ^T _k=[1 I_k(I_k-I_k-1)/△t(V_{T, k}-V_{T, k-1})/△t n_k-1…n_k-nc] calculate the moment The recursion value Γ of k input vector, wherein Γ^T ₁=Γ^T ₂=...=Γ^T _nc=Γ₀, Γ₀For given initial value, I, V_tTo pass through Electric current when electric discharge (be negative when charging, be positive), the end voltage of the battery of sensor sample, subscript k represents the kth moment, k-1 is represented - 1 moment of kth, time of the △ t between -1 moment of kth moment and kth, n_k-1、…、n_k-ncWhen respectively previous moment k-1, preceding nc Carve the random error of k-nc；

Step 502 presses formula P_k=[P_k-1-P_k-1Γ_kΓ^T _kP_k-1/(λ+Γ^T _kP_k-1Γ_k)]/λ update the kth moment gain Factor P_k, wherein subscript k, k-1 respectively represents kth moment and k-1 moment, and λ is that (usual value interval is 0.95- to forgetting factor 1)；

Step 503 presses formula 0_k=0_k-1+P_kΓ_k[V_{T, k}-Γ^T _k0_k-1] calculate the kth moment parameter vector to be identified 0_k；

Step 504, electric current I and end voltage V in k+1 moment battery_tAfter sampled value updates, by formula n_k+1-i= V_{T, k+1-i}-Γ^T _k+1-i0_k+1-i(i=1,2,3 ..., nc) updates the random error at pervious nc moment at current time, by k k+ 1 replaces, and return step 501 realizes recursion；

Step 505, using obtaining parameter vector 0 to be identified in step 501-504 recurrence calculation_kIn element 0_{1, k}、 0_{2, k}、0_{3, k}、0_{4, k}, formula V is pressed respectively_oc=0_{1, k}、R_in=0_{3, k}/0_{4, k}、R_p=-0_{2, k}-0_{3, k}/0_{4, k}、C_p=0_{4, k} ²/(0_{2, k}0_{4, k}+ 0_{3, k}) calculate battery open circuit voltage V in battery equivalent circuit model_oc, DC internal resistance R_in, R in RC circuit_pAnd C_p。

The step 6 specifically comprises the following steps:

Step 601 utilizes the relationship of the SOC of the battery based on identical electrochemical system and the open-circuit voltage of battery and temperature The principle not changed with cell degradation measures the relationship of single battery SOC Yu its open-circuit voltage Voc and temperature T by testing SOC^{OCV, T}=f (Voc, T) uses the open-circuit voltage V for the single battery that recursion on-line identification in step 5 goes out_{Oc, i, j}With the step Single battery temperature Ts obtained in 4_{I, j}Instead of SOC^{OCV, T}Voc and T in=f (Voc, T) calculate the mould of single battery (i, j) Type state-of-charge SOC^Model _{I, j}；

Step 602 utilizes single battery electric current Is obtained in step 4_{I, j}, by formula

SOC^Ah _{I, j}=∑ (Is_{I, j}△ t) calculate single battery (i, j) integral state-of-charge SOC^Ah _{I, j}, wherein；△ t is Front and back Is twice_{I, j}Time interval between update；

Step 603, the state-of-charge SOC for calculating single battery (i, j) according to the following steps_{I, j}:

1) if the battery standing time is more than setting time T1, SOC_{I, j}=SOC^{OCV, T}=f (Voc, T), wherein Voc is After BMS is powered on | Is_{I, j}| the electric current Is of the single battery obtained in the step 4 during being approximately 0_{I, j}；

If 2) | V^m _{I, j}-Vs_{I, j}| < δ, then SOC_{I, j}=SOC^Model _{I, j}, wherein δ is voltage difference for judging the step Whether the single battery parameter that recursion on-line identification goes out in 5 is accurate (generally taking, 10-20mV), V^m _{I, j}For the list being calculated as follows The voltage of body battery (i, j):

V^m _{I, j}=V_{Oc, i, j}-(R_{In, i, j}+R_{P, i, j})Is_{I, j}-R_{P, i, j}C_{P, i, j}(R_{In, i, j}△Is/△t+△Vs/△t)+W_{K, i, j}

In formula, V_{Oc, i, j}、R_{In, i, j}、R_{P, i, j}、C_{P, i, j}、W_{K, i, j}The single battery (i, j) respectively picked out in step 5 Open-circuit voltage, DC internal resistance, the resistance in the circuit RC and capacitor, coloured noise, △ t are the time at current time and previous moment Difference, △ Is=Is_{I, j}-Is_{I, j} ^-1, △ Vs=Vs_{I, j}-Vs_{I, j} ^-1, Is_{I, j} ^-1、Vs_{I, j} ^-1The respectively Vs of previous moment_{I, j}、Is_{I, j}, Vs_{I, j}、Is_{I, j}Respectively obtained in step 4 based on timestamp is soft synchronize after synchronization single battery voltage, electricity Stream；

If 3) (Vs_{I, j}> VH or Vs_{I, j}< VL) and | Is_{I, j}| < IL and | Is_{I, j}| the duration > Tlim of < IL, then Use Vs_{I, j}Instead of V, Ts_{I, j}SOC is calculated instead of T_{I, j}=f1 (V, T), wherein f1 (V, T) is the single battery obtained by experiment The relationship of SOC and its voltage V and temperature T, VH, VL, IL, Tlim be respectively pass through experiment obtain to battery carry out constant current voltage limiting Monomer battery voltage when charging close to full of electricity condition, when carrying out constant current voltage limiting electric discharge close to single battery electricity when emptying Pressure, for judging whether reach the current value of pressure limiting state in constant-current charging of battery or discharge process, for confirming battery constant current Whether the time of pressure limiting state is reached during charge or discharge；

4) otherwise, SOC_{I, j}=SOC^Ah _{I, j}。

The monomer battery voltage of sampling, temperature and time stamp are sent to master control by CAN bus by each local controller BMU Device BMU processed executes the step 5- step 6 by BMU.

Compared with prior art, the invention has the following advantages that

1) the present invention is based on the framework of existing battery management system, the lotus to single battery each in series-connected cell group is realized The On-line Estimation of electricity condition SOC realizes the series-connected cell group SOC On-line Estimation based on single battery, at low cost, effectively prevent Battery is abused, rationally adequately using the ability of series-connected cell group during real time execution, to be conducive to extend series connection The service life of battery pack reduces its use cost.

2) via experimental verification, the present invention has high-precision of the series-connected cell group SOC evaluated error less than 3%, and can be right The different use environment conditions of series-connected cell group, operating condition have adaptivity in its life cycle management.

Detailed description of the invention

Fig. 1 is the stream of state of charge of series-connected batteries SOC On-line Estimation method of the embodiment of the present invention based on single battery Journey schematic diagram.

Specific embodiment

The present invention is described in detail combined with specific embodiments below.Following embodiment will be helpful to the technology of this field Personnel further understand the present invention, but the invention is not limited in any way.It should be pointed out that the ordinary skill of this field For personnel, without departing from the inventive concept of the premise, various modifications and improvements can be made.These belong to the present invention Protection scope.

As shown in Figure 1, the embodiment of the invention provides a kind of, the state of charge of series-connected batteries SOC based on single battery exists Line estimation method, which comprises the steps of:

Step 1, central controller BCU send sample start times benchmark TB and soft synchronized sampling time interval △ t to institute There is local controller BMU；

Step 2, central controller BCU since TB, carried out at interval of △ t to by the electric current of the series-connected cell group It samples, and the current sequence I of series-connected cell group will be passed through_NIAnd its timestamp n of corresponding sampling_NIIt is sent by CAN bus To each local controller BMU, wherein n_NIFor I_NIThe number of △ t between sampling instant and TB, subscript NI are to sample resulting lead to Cross the serial number of the current value of series-connected cell group；

Step 3, each local controller BMU are since TB, at interval of △ t by its synchronized sampling holding circuit to series electrical The voltage of the corresponding single battery of its in the group of pond, temperature are sampled, and the voltage V of single battery is obtained_{I, j} ^NC, temperature T_{I, j} ^NC, Record each V_{I, j} ^NC、T_{I, j} ^NCThe number n of △ t between sampling instant and TB_{I, j} ^NCAs V_{I, j} ^NC、T_{I, j} ^NCThe timestamp of sampling, In, subscript i is the number of local controller BMU, subscript j is single battery corresponding to i-th of local controller BMU volume Number, subscript NC is the voltage value for sampling resulting single battery, the serial number of temperature value；

Step 4, each local controller BMU receive the current value I from central controller BCU by CAN bus_NIAnd its phase The n answered_NI, by n_{I, j} ^NC=n_NIThe voltage V of corresponding single battery_{I, j} ^NC, temperature T_{I, j} ^NCWith I_NICombo, to obtain based on the time The voltage Vs of the single battery of synchronization after stabbing soft synchronize_{I, j}, electric current Is_{I, j}With temperature Ts_{I, j}；

Step 5, each local controller use the voltage Vs of each single battery respectively_{I, j}, electric current Is_{I, j}With temperature Ts_{I, j}, hold Row is based on each single battery parameter in battery equivalent circuit model and to being not covered by battery effect in battery equivalent circuit model Carry out the recursion on-line identification of each single battery parameter of comprehensive simulation；

Step 6, each local controller execute the adaptive state-of-charge SOC estimation method of both-end self-correcting, obtain each monomer The state-of-charge SOC of battery_{I, j}, and by SOC_{I, j}Central controller BCU is sent to by CAN bus；

Step 7, central controller BCU are calculated by the following formula the state-of-charge SOC of series-connected cell group^BP

SOC^BP=min [SOC_{I, j},

In formula, the number of i=1- local controller BMU, single battery corresponding to i-th of local controller BMU of j=1- Number.

Each local controller in the step 5 uses the voltage Vs of each single battery respectively_{I, j}, electric current Is_{I, j}And temperature Ts_{I, j}, execute based on each single battery parameter in battery equivalent circuit model and to being not covered by electricity in battery equivalent circuit model Pond effect carries out the recursion on-line identification of each single battery parameter of comprehensive simulation, and the battery equivalent circuit model is Thevenin model, each single battery parameter in the battery equivalent circuit model include the open-circuit voltage of single battery V_{Oc, i, j}, single battery DC internal resistance R_{In, i, j}, charge transfer phenomenon for simulating single battery the circuit RC in resistance R_{P, i, j}With capacitor C_{P, i, j}, the monomer electricity that battery effect carries out comprehensive simulation is not covered by moment k, battery equivalent circuit model Pond parameter is the coloured noise added as constructed by the sliding average of white noise in the output end of battery equivalent circuit model W_{K, i, j}。

The method of the recursion on-line identification is recursion extended least squares method, to each single battery (i, j, i=1- sheet The number of ground controller BMU, the number of single battery corresponding to i-th of local controller BMU of j=1-), it clocks when carving k The Vs of single battery (i, j)_{I, j}, electric current Is_{I, j}With temperature Ts_{I, j}Respectively V_{T, k}、I_k、T_k, specifically comprise the following steps:

Step 501 presses formula Γ^T _k=[1 I_k(I_k-I_k-1)/△t(V_{T, k}-V_{T, k-1})/△t n_k-1…n_k-nc] calculate the moment The recursion value Γ of k input vector, wherein Γ^T ₁=Γ^T ₂=...=Γ^T _nc=Γ₀, Γ₀For given initial value, I, V_tTo pass through Electric current when electric discharge (be negative when charging, be positive), the end voltage of the battery of sensor sample, subscript k represents the kth moment, k-1 is represented - 1 moment of kth, time of the △ t between -1 moment of kth moment and kth, n_k-1、…、n_k-ncWhen respectively previous moment k-1, preceding nc Carve the random error of k-nc；

Step 502 presses formula P_k=[P_k-1-P_k-1Γ_kΓ^T _kP_k-1/(λ+Γ^T _kP_k-1Γ_k)]/λ update the kth moment gain Factor P_k, wherein subscript k, k-1 respectively represents kth moment and k-1 moment, and λ is that (usual value interval is 0.95- to forgetting factor 1)；

Step 503 presses formula 0_k=0_k-1+P_kΓ_k[V_{T, k}-Γ^T _k0_k-1] calculate the kth moment parameter vector to be identified 0_k；

Step 504, electric current I and end voltage V in k+1 moment battery_tAfter sampled value updates, by formula n_k+1-i= V_{T, k+1-i}-Γ^T _k+1-i0_k+1-i(i=1,2,3 ..., nc) updates the random error at pervious nc moment at current time, by k k+ 1 replaces, and return step 501 realizes recursion；

Step 505, using obtaining parameter vector 0 to be identified in step 501-504 recurrence calculation_kIn element 0_{1, k}、 0_{2, k}、0_{3, k}、0_{4, k}, formula V is pressed respectively_oc=0_{1, k}、R_in=0_{3, k}/0_{4, k}、R_p=-0_{2, k}-0_{3, k}/0_{4, k}、C_p=0_{4, k} ²/(0_{2, k}0_{4, k}+ 0_{3, k}) calculate battery open circuit voltage V in battery equivalent circuit model_oc, DC internal resistance R_in, R in RC circuit_pAnd C_p。

The step 6 specifically comprises the following steps:

Step 601 utilizes the relationship of the SOC of the battery based on identical electrochemical system and the open-circuit voltage of battery and temperature The principle not changed with cell degradation measures the relationship of single battery SOC Yu its open-circuit voltage Voc and temperature T by testing SOC^{OCV, T}=f (Voc, T) uses the open-circuit voltage V for the single battery that recursion on-line identification in step 5 goes out_{Oc, i, j}With the step Single battery temperature Ts obtained in 4_{I, j}Instead of SOC^{OCV, T}Voc and T in=f (Voc, T) calculate the mould of single battery (i, j) Type state-of-charge SOC^Model _{I, j}；

Step 602 utilizes single battery electric current Is obtained in step 4_{I, j}, by formula

SOC^Ah _{I, j}=∑ (Is_{I, j}△ t) calculate single battery (i, j) integral state-of-charge SOC^Ah _{I, j}, wherein；△ t is Front and back Is twice_{I, j}Time interval between update；

Step 603, the state-of-charge SOC for calculating single battery (i, j) according to the following steps_{I, j}:

1) if the battery standing time is more than setting time T1, SOC_{I, j}=SOC^{OCV, T}=f (Voc, T), wherein Voc is After BMS is powered on | Is_{I, j}| the electric current Is of the single battery obtained in the step 4 during being approximately 0_{I, j}；

If 2) | V^m _{I, j}-Vs_{I, j}| < δ, then SOC_{I, j}=SOC^Model _{I, j}, wherein δ is voltage difference for judging the step Whether the single battery parameter that recursion on-line identification goes out in 5 is accurate (generally taking, 10-20mV), V^m _{I, j}For the list being calculated as follows The voltage of body battery (i, j):

V^m _{I, j}=V_{Oc, i, j}-(R_{In, i, j}+R_{P, i, j})Is_{I, j}-R_{P, i, j}C_{P, i, j}(R_{In, i, j}△Is/△t+△Vs/△t)+W_{K, i, j}

In formula, V_{Oc, i, j}、R_{In, i, j}、R_{P, i, j}、C_{P, i, j}、W_{K, i, j}The single battery (i, j) respectively picked out in step 5 Open-circuit voltage, DC internal resistance, the resistance in the circuit RC and capacitor, coloured noise, △ t are the time at current time and previous moment Difference, △ Is=Is_{I, j}-Is_{I, j} ^-1, △ Vs=Vs_{I, j}-Vs_{I, j} ^-1, Is_{I, j} ^-1、Vs_{I, j} ^-1The respectively Vs of previous moment_{I, j}、Is_{I, j}, Vs_{I, j}、Is_{I, j}Respectively obtained in step 4 based on timestamp is soft synchronize after synchronization single battery voltage, electricity Stream；

If 3) (Vs_{I, j}> VH or Vs_{I, j}< VL) and | Is_{I, j}| < IL and | Is_{I, j}| the duration > Tlim of < IL, then Use Vs_{I, j}Instead of V, Ts_{I, j}SOC is calculated instead of T_{I, j}=f1 (V, T), wherein f1 (V, T) is the single battery obtained by experiment The relationship of SOC and its voltage V and temperature T, VH, VL, IL, Tlim be respectively pass through experiment obtain to battery carry out constant current voltage limiting Monomer battery voltage when charging close to full of electricity condition, when carrying out constant current voltage limiting electric discharge close to single battery electricity when emptying Pressure, for judging whether reach the current value of pressure limiting state in constant-current charging of battery or discharge process, for confirming battery constant current Whether the time of pressure limiting state is reached during charge or discharge；

4) otherwise, SOC_{I, j}=SOC^Ah _{I, j}。

The monomer battery voltage of sampling, temperature and time stamp are sent to master control by CAN bus by each local controller BMU Device BMU processed executes the step 5- step 6 by BMU.

Framework of this specific implementation based on existing battery management system is realized to single battery each in series-connected cell group The On-line Estimation of state-of-charge SOC realizes the series-connected cell group SOC On-line Estimation based on single battery, at low cost, effectively anti- Only battery is abused, rationally adequately using the ability of series-connected cell group during real time execution, to be conducive to extend string Join the service life of battery pack, reduce its use cost；Via experimental verification, there is the present invention series-connected cell group SOC estimation to miss High-precision of the difference less than 3%, and can different use environment conditions to series-connected cell group, operating condition in its life cycle management With adaptivity.

Specific embodiments of the present invention are described above.It is to be appreciated that the invention is not limited to above-mentioned Particular implementation, those skilled in the art can make various deformations or amendments within the scope of the claims, this not shadow Ring substantive content of the invention.

Claims (1)

1. a kind of state of charge of series-connected batteries SOC On-line Estimation method based on single battery, which is characterized in that including as follows Step:

Step 1, central controller BCU send sample start times benchmark TB and soft synchronized sampling time interval △ t to all Ground controller BMU；

Step 2, central controller BCU sample the electric current by the series-connected cell group since TB, at interval of △ t, And the current sequence I of series-connected cell group will be passed through_NIAnd its timestamp n of corresponding sampling_NIEach is sent to by CAN bus Ground controller BMU, wherein n_NIFor I_NIThe number of △ t between sampling instant and TB, NI, which is that sampling is resulting, passes through series-connected cell The serial number of the current value of group；

Step 3, each local controller BMU are since TB, at interval of △ t by its synchronized sampling holding circuit to series-connected cell group In the voltage of its corresponding single battery, temperature sampled, obtain the voltage V of single battery_i,j ^NC, temperature T_i,j ^NC, record Each V_i,j ^NC、T_i,j ^NCThe number n of △ t between sampling instant and TB_i,j ^NCAs V_i,j ^NC、T_i,j ^NCThe timestamp of sampling, wherein i It is the number of single battery corresponding to i-th of local controller BMU for the number of local controller BMU, j, subscript NC is to adopt The serial number of the voltage value of the resulting single battery of sample, temperature value；

Step 4, each local controller BMU receive the current value I from central controller BCU by CAN bus_NIAnd its it is corresponding n_NI, by n_i,j ^NC=n_NIThe voltage V of corresponding single battery_i,j ^NC, temperature T_i,j ^NCWith I_NICombo, to obtain soft based on timestamp The voltage Vs of the single battery of synchronization after synchronizing_i,j, electric current Is_i,jWith temperature Ts_i,j；

Step 5, each local controller use the voltage Vs of each single battery respectively_i,j, electric current Is_i,jWith temperature Ts_i,j, execute base It each single battery parameter in battery equivalent circuit model and is carried out to battery effect is not covered by battery equivalent circuit model The recursion on-line identification of each single battery parameter of comprehensive simulation；

Step 6, each local controller execute the adaptive state-of-charge SOC estimation method of both-end self-correcting, obtain each single battery State-of-charge SOC_i,j, and by SOC_i,jCentral controller BCU is sent to by CAN bus；

Step 7, central controller BCU are calculated by the following formula the state-of-charge SOC of series-connected cell group^BP:

SOC^BP=min [SOC_i,j],

The number that in formula, i is the number of local controller BMU, j is single battery corresponding to i-th of local controller BMU；

Each local controller in the step 5 uses the voltage Vs of each single battery respectively_i,j, electric current Is_i,jWith temperature Ts_i,j, It executes based on each single battery parameter in battery equivalent circuit model and is imitated to battery is not covered by battery equivalent circuit model The recursion on-line identification of each single battery parameter of comprehensive simulation should be carried out, the battery equivalent circuit model is Dai Weinanmo Type, each single battery parameter in the battery equivalent circuit model include the open-circuit voltage V of single battery_oc,i,j, single battery DC internal resistance R_in,i,j, charge transfer phenomenon for simulating single battery the circuit RC in resistance R_p,i,jAnd capacitor C_p,i,j, it is by white that battery effect is not covered by moment k, battery equivalent circuit model and carries out the single battery parameter of comprehensive simulation The coloured noise w added constructed by the sliding average of noise in the output end of battery equivalent circuit model_k,i,j；

The method of the recursion on-line identification is recursion extended least squares method, to each single battery (i, j), wherein i is this The number of ground controller BMU, the number that j is single battery corresponding to i-th of local controller BMU, the monomer to clock when carving k The Vs of battery (i, j)_i,j, electric current Is_i,jWith temperature Ts_i,jRespectively V_t,k、I_k、T_k, specifically comprise the following steps:

Step 501 presses formula Γ^T _k=[1 I_k (I_k-I_k-1)/△t (V_t,k-V_t,k-1)/△t n_k-1…n_k-nc] calculate moment k it is defeated The recursion value Γ of incoming vector, wherein Γ^T ₁=Γ^T ₂=...=Γ^T _nc=Γ₀,Γ₀For given initial value, I, V_tIt is passed to pass through The electric current and end voltage of the battery of sensor sampling, wherein electric current is negative when charging, and when electric discharge is positive, and k represents kth moment, k-1 Represent -1 moment of kth, time of the △ t between -1 moment of kth moment and kth, n_k-1、n_k-ncRespectively previous moment k-1, preceding nc The random error of moment k-nc；

Step 502 presses formula P_k=[P_k-1-P_k-1Γ_kΓ^T _kP_k-1/(λ+Γ^T _k P_k-1Γ_k)]/λ update the kth moment gain factor P_k, wherein k, k-1 respectively represent kth moment and k-1 moment, and λ is forgetting factor, value interval 0.95-1；

Step 503 presses formula θ_k=θ_k-1+P_kΓ_k[V_t,k-Γ^T _kθ_k-1] calculate the kth moment parameter vector θ to be identified_k；

Step 504, electric current I and end voltage V in k+1 moment battery_tAfter sampled value updates, by formula n_k+1-i=V_t,k+1-i- Γ^T _k+1-iθ_k+1-i, i=1,2,3 ..., nc；The random error for updating the pervious nc moment at current time, k is replaced with k+1, Return step 501 realizes recursion；

Step 505, using obtaining parameter vector θ to be identified in step 501-504 recurrence calculation_kIn element θ_1,k、θ_2,k、 θ_3,k、θ_4,k, formula V is pressed respectively_oc=θ_1,k、R_in=θ_3,k/θ_4,k、R_p=-θ_2,k-θ_3,k/θ_4,k、C_p=θ_4,k ²/(θ_2,kθ_4,k+θ_3,k) Calculate the battery open circuit voltage V in battery equivalent circuit model_oc, DC internal resistance R_in, R in RC circuit_pAnd C_p；

The step 6 specifically comprises the following steps:

Step 601, using the relationship of the SOC of the battery based on identical electrochemical system and the open-circuit voltage of battery and temperature not with Cell degradation and the principle changed measure the relationship of single battery SOC Yu its open-circuit voltage Voc and temperature T by testing SOC^{OCV, T}=f (Voc, T) uses the open-circuit voltage V for the single battery that recursion on-line identification in step 5 goes out_oc,i,jWith the step Single battery temperature Ts obtained in 4_i,jInstead of SOC^{OCV, T}Voc and T in=f (Voc, T) calculate the mould of single battery (i, j) Type state-of-charge SOC^Model _i,j；

Step 602 utilizes single battery electric current Is obtained in step 4_i,j, by formula

SOC^Ah _i,j=∑ (Is_i,j△ t) calculate single battery (i, j) integral state-of-charge SOC^Ah _i,j, wherein；△ t is front and back two Secondary Is_i,jTime interval between update；

Step 603, the state-of-charge SOC for calculating single battery (i, j) according to the following steps_i,j:

1) if the battery standing time is more than setting time T1, SOC_i,j=SOC^{OCV, T}=f (Voc, T), wherein Voc BCU After powering on | Is_i,j| the voltage of the single battery obtained in the step 4 during being approximately 0；

If 2) | V^m _i,j-Vs_i,j| < δ, then SOC_i,j=SOC^Model _i,j, wherein δ is voltage difference for judging to pass in the step 5 Whether accurate push away the single battery parameter that on-line identification goes out, value 10-20mV, V^m _i,jFor be calculated as follows single battery (i, J) voltage:

V^m _i,j=V_oc,i,j-(R_in,i,j+R_p,i,j)Is_i,j-R_p,i,jC_p,i,j(R_in,i,j△Is/△t+△Vs/△t)+w_k,i,j

In formula, V_oc,i,j、R_in,i,j、R_p,i,j、C_p,i,j、w_k,i,jThe open circuit of the single battery (i, j) respectively picked out in step 5 Voltage, DC internal resistance, the resistance in the circuit RC and capacitor, coloured noise, △ t are the time difference at current time and previous moment, △ Is=Is_i,j-Is_i,j ^-1, △ Vs=Vs_i,j-Vs_i,j ^-1, Is_i,j ^-1、Vs_i,j ^-1The respectively Vs of previous moment_i,j、Is_i,j, Vs_i,j、 Is_i,jRespectively obtained in step 4 based on timestamp is soft synchronize after synchronization single battery voltage, electric current；

If 3) Vs_i,j> VH or Vs_i,j< VL and | Is_i,j| < IL and | Is_i,j|<duration of IL>Tlim then uses Vs_i,jInstead of V、Ts_i,jSOC is calculated instead of T_i,j=f1 (V, T), wherein f1 (V, T) is the single battery SOC and its voltage obtained by experiment The relationship of V and temperature T, VH, VL, IL, Tlim are respectively to pass through approaching when carrying out onstant current voltage limiting to charge to battery for experiment acquisition Monomer battery voltage when full of electricity condition, when carrying out constant current voltage limiting electric discharge close to when emptying monomer battery voltage, for sentencing Whether reach the current value of pressure limiting state in disconnected constant-current charging of battery or discharge process, for confirming constant-current charging of battery or electric discharge Whether reach the time of pressure limiting state in the process；

4) otherwise, SOC_i,j=SOC^Ah _i,j。