陳英杰 楊耕 劉旭
關(guān)鍵詞:鋰離子電池;熱模型;參數(shù)估計(jì);內(nèi)阻;開路電壓;熱容;換熱系數(shù)
DOI:10.15938/j.emc.2019.06.000
中圖分類號(hào)文獻(xiàn)標(biāo)志碼:A 文章編號(hào):1007 -449X(2019)06 -0000 -00
Abstract:Internal resistance(R), open circuit voltage(Uocv), heat capacity(mCH) and heat transfer coefficient(k) are key parameters of lithiumion battery thermal model based on simplified Bernardi equation. R and Uocv are nonlinear functions of state of charge(SOC), current(I) and battery temperature(Tbat) and mCH and k are constants. Since the hidden battery properties behind these parameters are different, existing estimation methods usually conduct different tests to excite corresponding properties respectively, resulting in massive test time and labor. This paper proposes a thermal parameters estimation method only consisting of constant current tests and corresponding data dealing procedures. The constant current tests are conducted under various ambient temperatures to provide necessary data within short test time. The battery mechanism based data dealing procedures consider the parameters nonlinear characteristics and solve the SOC and Tbat coupling variation problem. Compared with existing method, the proposed method can provide accurate R(SOC,I,Tbat), Uocv(SOC,Tbat), mCH and k estimation results simultaneously within short test time, thus more engineering applicable. Test results have verified the advantages.
Keywords:lithiumion batteries; thermal model; parameter estimation; internal resistance; open circuit voltage; heat capacity; heat transfer coefficient
0 引 言
鋰離子電池的功率和能量輸出能力[1]、老化速率[2]、安全性[3]等指標(biāo)均與電池溫度(Tbat)密切相關(guān)。而在電池工作過程中,電池不斷產(chǎn)熱/吸熱,并與周圍環(huán)境發(fā)生熱交換,Tbat不斷變化,需要熱模型描述Tbat的變化規(guī)律,并依此進(jìn)行熱管理工作。本文的目的即在于提出一種簡(jiǎn)便的熱模型參數(shù)估計(jì)方法。
4 結(jié) 論
本文提出了一種僅僅基于恒電流實(shí)驗(yàn)的估計(jì)鋰離子電池的熱模型參數(shù)的工程性方法。模型參數(shù)有:開路電壓Uocv(SOC,Tbat)、直流內(nèi)阻R(SOC,I,Tbat)和mCH、k。
方法的核心是一組含典型Tamb和典型恒流的實(shí)驗(yàn)設(shè)計(jì)和一套基于鋰離子電池的電化學(xué)機(jī)理的模型參數(shù)估計(jì)算法。據(jù)此,方法解決了恒流放電過程中SOC與Tbat同時(shí)耦合變化以及U-I非線性關(guān)系等問題。由于本方法僅需要一組恒流實(shí)驗(yàn)以及相關(guān)數(shù)據(jù)處理算法,與需要進(jìn)行多組實(shí)驗(yàn)分別估計(jì)上述參數(shù)的現(xiàn)有方法相比,方法的實(shí)驗(yàn)時(shí)間縮短了50%以上。同時(shí),方法具有足夠的精確度。實(shí)驗(yàn)驗(yàn)證了方法的上述特征。
目前,方法基于對(duì)電池各部分溫度一致的假設(shè)。這一假設(shè)在大電流條件下對(duì)于一些結(jié)構(gòu)的電池而言誤差較為明顯,因此還需進(jìn)一步改進(jìn)。
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(編輯:賈志超)