MAtlab battery modeling simulation.pptx

Battery modeling, Matlab, SImulation,

1. 10mins report in D . T . Laboratory Reporter Name: XiaoYong Yang Date: 21-Fri-2021 The Matlab Simulation of Parameters Verification Based on Thevenin Model for Lithium-ion Battery

2. CONTENTS 1 2 Equivalent Circuit Model Parameter Identification 3 Model Verification

3. 1. Equivalent circuit model Thevenin model is a nonlinear low-order model with simple structure and fewer parameters, and its accuracy can meet the requirements of engineering applications. Based on this model, the influence of polarization phenomenon on the voltage and the SOC itself is fully considered, and the nonlinear state space equation is obtained, and then the SOC is estimated. Fig. 1: Thevenin equivalent model U OC : Open circuit voltage for battery U : Battery terminal voltage : Battery internal resistance : Battery internal polarization resistance C P : Battery internal polarization capacitance   I(t)= + (1) (2)  

4. 1. Equivalent circuit model 1 For parameter identification of Thevenin model, HPPC test experiment was carried out first, then all voltage and current data were extracted from the original data, so as to obtain the changes of voltage and current of lithium-ion battery in HPPC test experiment. The constant current discharge experiment is shown in Fig.2. Fig.2 Current and voltage curves of HPPC test

5. 2. Parameter identification A curve-fitting method is used for parameter identification. Taking the SOC=0.9 data segment as an example, the parameters of , and in Thevenin model can be calculated from the value of a, b and c according to formula (5) to (8). Pulse test diagram at SOC=0.9 is shown in Fig.3.   Fig. 3: HPPC voltage curve a= (5) b= (6) c= (7) = (8)   （ 3 ）   ) （ 4 ）  

6. Fig.5 Identification parameters of curve fitting method w hen SOC = 0.9 The curve fitting was carried out on MATLAB .Through the Eq. 4, the fitting values is obtained in Fig.4 when SOC=0.9 and i dentification parameters of curve fitting method is shown in Fig.5 w hen SOC = 0.9. Fig.4 Values of a ， b ， c w hen SOC=0.9. 2. Parameter identification

7. Table 1 parameter identification results 2. Parameter identification a b c 0.1 3.537 3.443 0.03158 82.6 0.001306 0.000451 183090.6 0.2 3.589 3.502 0.02782 94.82 0.001236 0.000397 238583.8 0.3 3.6154 3.531 0.026 93.64 0.001202 0.000371 252107.7 0.4 3.6492 3.567 0.02495 87.84 0.001174 0.000356 246444.9 0.5 3.7248 3.644 0.03463 90.62 0.001151 0.000495 183176.4 0.6 3.8309 3.75 0.03782 96.85 0.001147 0.00054 179257 0.7 3.9366 3.857 0.03587 94.44 0.001141 0.000512 184298.9 0.8 4.0525 3.972 0.03243 87.69 0.001136 0.000463 189278.4 0.9 4.1849 4.104 0.02966 90.26 0.001147 0.000424 213020.9 a b c 0.1 3.537 3.443 0.03158 82.6 0.001306 0.000451 183090.6 0.2 3.589 3.502 0.02782 94.82 0.001236 0.000397 238583.8 0.3 3.6154 3.531 0.026 93.64 0.001202 0.000371 252107.7 0.4 3.6492 3.567 0.02495 87.84 0.001174 0.000356 246444.9 0.5 3.7248 3.644 0.03463 90.62 0.001151 0.000495 183176.4 0.6 3.8309 3.75 0.03782 96.85 0.001147 0.00054 179257 0.7 3.9366 3.857 0.03587 94.44 0.001141 0.000512 184298.9 0.8 4.0525 3.972 0.03243 87.69 0.001136 0.000463 189278.4 0.9 4.1849 4.104 0.02966 90.26 0.001147 0.000424 213020.9 According to the same method, , and from 0.1 to 0.9 are shown in Table.1.  

8. As is shown in Fig.6 to Fig.9 , the scatter diagram of the relationship between parameters and SOC can obtained based on the parameter identification results. Fig.6 .   Fig.7 .   Fig.8 .   Fig.9 .   2. Parameter identification

9. 3.Model Verification Fig. 10 Model Validation Simulink Simulation The obtained model parameters need to verify their accuracy. The method is to put the identified parameters into the Thevenin equivalent circuit model, input the same current as the HPPC test experiment, compare the output voltage response data of the model with the actual voltage data, and optimize the model according to the verification results. The Simulink simulation diagram of model verification is shown in the Fig.10.

10. 3.Model Verification Fig. 11 Thevenin Model Simulink Simulation The interior of the Thevenin model is shown in Fig.11 .

11. Fig. 12 . Thevenin equivalent circuit model simulation results 3.Model Verification As can be seen from the error curve in Fig 12, the red curve is the real voltage, and the yellow curve is the model voltage. The maximum error is 0.08. It occurs in the end of model test. Therefore, Though the Thevenin model error is within acceptable limits, but model could not well show the response effect of lithium-ion battery and it needs to be improved continually.

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