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JP2004031014A - Method and apparatus for calculating maximum charge / discharge power of battery pack including parallel connected batteries - Google Patents

Method and apparatus for calculating maximum charge / discharge power of battery pack including parallel connected batteries Download PDF

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JP2004031014A
JP2004031014A JP2002182920A JP2002182920A JP2004031014A JP 2004031014 A JP2004031014 A JP 2004031014A JP 2002182920 A JP2002182920 A JP 2002182920A JP 2002182920 A JP2002182920 A JP 2002182920A JP 2004031014 A JP2004031014 A JP 2004031014A
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parallel
battery
internal resistance
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discharge power
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Kenichi Sakai
酒井　健一
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Nissan Motor Co Ltd
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    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/392—Determining battery ageing or deterioration, e.g. state of health

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Abstract

【課題】並列に接続された電池を適切な領域で使用するように最大充放電電力を演算する方法を提供する。
【解決手段】単電池Ｃ１およびＣ２を並列に接続した並列電池と、単電池Ｃ３およびＣ４を並列に接続した並列電池と、単電池Ｃ５およびＣ６を並列に接続した並列電池と、単電池Ｃ７およびＣ８を並列に接続した並列電池とをそれぞれ直列に接続して組電池を構成する。組電池に流れる電流を電流センサ２０１で検出し、それぞれの並列電池の端子電圧をセル電圧検出部１０１で検出する。ＣＰＵ１０２は、直線回帰演算により並列電池ごとに最大放電電力Ｐｍａｘ（Ｐ）および最大充電電力ＰＣｍａｘ（Ｐ）を算出する。組電池の最大放電電力を算出するとき、並列電池ごとの最大放電電力Ｐｍａｘ（Ｐ）が最小となるの並列電池の放電電力に応じて組電池の最大放電電力を算出する。組電池の最大充電電力を算出するとき、並列電池ごとの最大充電電力ＰＣｍａｘ（Ｐ）が最小となる並列電池の放電電力に応じて組電池の最大充電電力を算出する。
【選択図】図１Provided is a method of calculating maximum charge / discharge power so that batteries connected in parallel are used in an appropriate region.
SOLUTION: A parallel battery in which cells C1 and C2 are connected in parallel, a parallel battery in which cells C3 and C4 are connected in parallel, a parallel battery in which cells C5 and C6 are connected in parallel, and a cell C7 and A parallel battery in which C8 is connected in parallel is connected in series to form an assembled battery. The current flowing through the assembled battery is detected by the current sensor 201, and the terminal voltage of each parallel battery is detected by the cell voltage detection unit 101. The CPU 102 calculates the maximum discharge power Pmax (P) and the maximum charge power PCmax (P) for each parallel battery by a linear regression calculation. When calculating the maximum discharge power of the battery pack, the maximum discharge power of the battery pack is calculated according to the discharge power of the parallel battery that minimizes the maximum discharge power Pmax (P) of each parallel battery. When calculating the maximum charge power of the battery pack, the maximum charge power of the battery pack is calculated according to the discharge power of the parallel battery in which the maximum charge power PCmax (P) for each parallel battery is minimum.
[Selection diagram] Fig. 1

Description

【０００１】
【発明の属する技術分野】
本発明は、並列に接続された電池を含む組電池の最大充放電電力演算方法および装置に関する。
【０００２】
【従来の技術】
電気自動車などのように、充電可能な二次電池を電源として負荷を駆動する技術が知られている。電池は、負荷を駆動する放電動作と電池を充電する充電動作とを繰り返し行う。このような電池の放電電力および充電電力は、それぞれが最大放電電力および最大充電電力以下となるように制御される。最大放電電力および最大充電電力を算出する方法として、電池の放電中に測定した端子電圧Ｖおよび放電電流Ｉに基づいてＩＶ特性を直線回帰演算する方法が提案されている（たとえば、特開平９−２１８２５１号公報参照）。一般に、リチウムイオン電池やニッケル水素電池は、電池の放電深度（ＤＯＤ）が所定の領域（たとえば、０〜６０％）で充電時と放電時の内部抵抗がほぼ一致する上に、充放電時のＩＶ特性の直線性がよい。そこで、電池の放電中に測定した端子電圧Ｖを縦軸に、放電電流Ｉを横軸にそれぞれ記し、得られたＩＶ特性から回帰直線を求める。この回帰直線を放電側の領域および充電側の領域へそれぞれ延長すると、Ｖ軸切片が電池の開放電圧を表す。最大放電電力は、回帰直線と放電時の放電停止電圧Ｖｍｉｎとの交点が示す電流Ｉｍａｘ、および放電停止電圧Ｖｍｉｎの積で与えられる。一方、最大充電電力は、回帰直線と許容最大電圧Ｖｍａｘとの交点が示す電流Ｉｃｍａｘ、および許容最大電圧Ｖｍａｘの積で与えられる。
【０００３】
【発明が解決しようとする課題】
複数の二次単電池を並列に接続した電池を上記電源に使用したいという要求がある。電池を並列に接続すると、電圧が高い側の電池から電圧が低い側の電池へ電流が流れる。この電流は調整電流と呼ばれ、電池間の端子電圧を合わせるように流れる。したがって、単電池を並列に接続した並列電池の端子電圧を測定しても単電池ごとの実際の開放電圧がわからないため、従来の方法では個々の単電池の状態を考慮して最大放電電力および最大充電電力を求めることが困難である。
【０００４】
本発明の目的は、並列に接続された二次単電池を適切な領域で使用するための最大放電電力と最大充電電力の少なくとも一方を演算する並列接続電池を含む組電池の最大充放電電力演算方法および装置を提供することにある。
【０００５】
【課題を解決するための手段】
本発明は、複数の二次単電池を並列に接続した並列電池を直列に複数接続した組電池の最大充放電電力を演算する方法に関し、組電池の放電時の並列電池ごとの電圧値、および放電時の組電池の電流値による特性から並列電池ごとに内部抵抗をそれぞれ算出し、算出した内部抵抗の最大値、および最大値に対応する並列電池以外の並列電池の内部抵抗値を用いて上記内部抵抗が最大値を有する並列電池を構成する単電池の内部抵抗の最大値を推定し、推定した内部抵抗の最大値に応じて最大放電電力と最大充電電力の少なくとも一方を算出するようにしたものである。
【０００６】
また、本発明は並列接続電池を含む組電池の最大充放電電力演算装置に関し、複数の二次単電池を並列に接続し、前記並列電池を直列に複数接続した組電池の放電時に、前記並列電池ごとの電圧を検出するとともに、組電池の放電時に、組電池を流れる電流を検出し、この検出された電圧および電流に基づいて、前記並列電池ごとの内部抵抗を算出し、この内部抵抗が最大の並列電池を抽出し、この抽出された並列電池の内部抵抗と、前記抽出された並列電池以外の並列電池の内部抵抗とを用いて、抽出された並列電池を構成する単電池の内部抵抗の最大値を推定し、この推定された内部抵抗の最大値に応じて、組電池の最大放電電力と最大充電電力の少なくとも一方を演算するようにしたものである。
【０００７】
【発明の効果】
本発明で並列接続電池を含む組電池の最大充放電電力を演算すると、組電池を構成する並列電池の単電池を適切な領域で使用できるので、電池の劣化を防止できる。
【０００８】
【発明の実施の形態】
以下、図面を参照して本発明の実施の形態を説明する。
図１は、本発明による方法で組電池の充放電電力を演算する制御ユニットを搭載した車両の全体構成図である。以下の実施の形態では、組電池を電気自動車の電源として適用した例を説明する。図１において、車両の制御システムは、車両システムと電池制御ユニットとで構成される。図中の太い実線は強電ライン（強電系の配線）を表し、通常の実線は弱電ライン（弱電系の配線）を示す。破線は各ブロック間で送受される信号ラインを示す。
【０００９】
車両システムは、電流センサ２０１と、電圧センサ２０２と、温度センサ２０３と、駆動用モータ３０１と、補機システム３０２と、メインリレー３０３Ａ，３０３Ｂとを有する。組電池は、二次単電池（セル）Ｃ１〜Ｃ８によって構成される。単電池Ｃ１およびＣ２、単電池Ｃ３およびＣ４、単電池Ｃ５およびＣ６、ならびに単電池Ｃ７およびＣ８は、それぞれ並列に接続されている。組電池は、これら４組の並列電池（Ｃ１，Ｃ２）、並列電池（Ｃ３，Ｃ４）、並列電池（Ｃ５，Ｃ６）、並列電池（Ｃ７，Ｃ８）が直列に接続されている。電池制御ユニットは、セル電圧検出部１０１と、ＣＰＵ１０２と、メモリ１０３とを有する。
【００１０】
駆動用モータ３０１は、組電池の直流電力が図示しないインバータを介して交流電力として供給されることで駆動し、車両の駆動力を発生する一方、組電池に対する回生電力を発生する。補機システム３０２は、組電池から供給される電力によって車両に搭載される不図示のエアコンディショナ（Ａ／Ｃ）などを駆動する。メインリレー３０３Ａ，３０３Ｂは、ＣＰＵ１０２の指令により開閉制御され、駆動モータ３０１および補機システム３０２への電力供給をオン／オフする。
【００１１】
電流センサ２０１は、強電ライン（＝組電池）を流れる電流を検出し、検出信号をＣＰＵ１０２へ送出する。電圧センサ２０２は、組電池の電圧（総電圧）を検出し、検出信号をＣＰＵ１０２へ送出する。温度センサ２０３は、組電池の温度を検出し、温度検出信号をＣＰＵ１０２へ送出する。
【００１２】
セル電圧検出部１０１は、並列電池（Ｃ１，Ｃ２）の端子電圧と、並列電池（Ｃ３，Ｃ４）の端子電圧と、並列電池（Ｃ５，Ｃ６）の端子電圧と、並列電池（Ｃ７，Ｃ８）の端子電圧とをそれぞれ検出し、４組の電圧情報をＣＰＵ１０２へ送出する。ＣＰＵ１０２は、４組の並列電池の電圧情報を用いて充電（回生）時の最大充電電力および放電時の最大放電電力を演算する。最大充放電電力の演算は、車両走行時（ＩＧＮスイッチオン時）、組電池の充電時に行う。最大充放電電力の演算結果は、ＣＰＵ１０２から車両システムＣＰＵ３０４へ送信される。ＣＰＵ１０２はさらに、組電池の温度が異常の場合に車両システムＣＰＵ３０４へ温度異常を報知する。
【００１３】
メモリ１０３は、ＣＰＵ１０２に入力された４組の並列電池の電圧情報や強電ライン（＝組電池）の電流の情報などを記憶する。
【００１４】
車両システムＣＰＵ３０４は、駆動用モータ３０１および補機システム３０２へ出力される電力がＣＰＵ１０２から受信した最大放電電力以下になるように、組電池から出力される電力を制限して車両システムを制御する。また、車両システムＣＰＵ３０４は、駆動モータ３０１から回生される電力がＣＰＵ１０２から受信した最大充電電力以下になるように、組電池を充電する電力を制限して車両システムを制御する。車両警告灯３０５は、車両システムＣＰＵ３０４の指令により点灯し、車両システムの異常発生を運転者に報知する。補助電池４０１は、ＣＰＵ１０２および車両システムＣＰＵ３０４へ電力を供給する。スイッチＳＷは、運転者によるイグニション（ＩＧＮ）スイッチ４０２のオン／オフに連動し、補助電池４０１からの電力供給をオン／オフする。
【００１５】
本発明は、上記組電池の放電時の最大放電電力および充電（回生）時の最大充電電力の演算方法に特徴を有する。
【００１６】
ＣＰＵ１０２は、最大放電電力の演算を以下の手順で行う。
▲１▼並列電池ごとに端子電圧および電流を測定する。
▲２▼並列電池ごとに最大放電電力を算出する。
▲３▼最大放電電力が最小のものを抽出する。
▲４▼抽出した並列電池を構成する単電池の中で最も大きい内部抵抗ＲＣｍａｘを推定する。
▲５▼内部抵抗ＲＣｍａｘと、他の単電池の内部抵抗ＲＣａｖｅとの比を算出する。
▲６▼組電池の最大放電電力を算出する。
【００１７】
１．並列電池ごとの端子電圧および電流の測定
ＣＰＵ１０２は、セル電圧検出部１０から４組の並列電池Ｃ（Ｐ１）（単電池Ｃ１およびＣ２で構成）、並列電池Ｃ（Ｐ２）（単電池Ｃ３およびＣ４で構成）、並列電池Ｃ（Ｐ３）（単電池Ｃ５およびＣ６で構成）、および並列電池Ｃ（Ｐ４）（単電池Ｃ７およびＣ８で構成）の端子電圧を示す情報をそれぞれ入力するとともに、電流センサ２０１から強電ラインの電流を示す情報を入力する。強電ラインに流れる電流値は、各並列電池の電流値（たとえば、単電池Ｃ１を流れる電流値と単電池Ｃ２を流れる電流値との合計の電流値）に等しい。
【００１８】
２．並列電池ごとの最大放電電力の算出
ＣＰＵ１０２は、放電中の複数回の測定によって得た電圧情報が示す電圧値、および電流情報が示す電流値を用いて各並列電池ごとにＩＶ特性を直線回帰演算する。図２は、回帰直線を説明する図であり、放電中の並列電池の電流Ｉ，電圧Ｖを測定し、その測定データから得たものである。リチウムイオン電池やニッケル水素電池などのように充電時と放電時とで電池の内部抵抗がほぼ一致し、さらに充放電時のＩＶ特性の直線性がよい電池は、放電側で測定したデータをもとに回帰直線を充電側に延長することができる。図中の×印は測定データを表している。
【００１９】
図２の回帰直線は、次式（１）で表わすことができる。
【数１】
Ｖ（Ｐ）＝Ｅ０（Ｐ）−Ｉ×Ｒ（Ｐ）　　　　　　　　　　　　　　　　（１）
ただし、Ｖ（Ｐ）は並列電池の端子電圧、Ｖ軸切片Ｅ０（Ｐ）は並列電池の開放電圧、回帰直線の傾きＲ（Ｐ）は並列電池の内部抵抗である。
【００２０】
本実施の形態では、並列電池の開放電圧Ｅ０（Ｐ）を回帰直線によって推定する。無負荷時の電圧を測定して開放電圧を得る方法もあるが、充放電ＩＶ特性の直線性がよい電池は推定開放電圧と実際の開放電圧とがよく一致するので、放電中の測定値によるＩＶ特性を用いて推定する。
【００２１】
図２において、回帰直線と放電時の放電停止電圧Ｖｍｉｎ（Ｐ）との交点Ｂの電流Ｉｍａｘ（Ｐ）は、並列電池の最大放電電流となる。並列電池の最大放電電力Ｐｍａｘ（Ｐ）は、上式（１）により次式（２）で算出される。
【数２】

Figure 2004031014
【００２２】
３．最大放電電力が最小の並列電池を抽出
ＣＰＵ１０２は、上述したように算出した４組の並列電池Ｃ（Ｐ１）〜Ｃ（Ｐ４）の最大放電電力Ｐｍａｘ（Ｐ１）、Ｐｍａｘ（Ｐ２）、Ｐｍａｘ（Ｐ３）、Ｐｍａｘ（Ｐ４）の中で、最小値のものを抽出する。以後、抽出した最小値をＰｍａｘ（Ｐｍｉｎ）と記す。また、Ｐｍａｘ（Ｐｍｉｎ）に対応する並列電池をＣ（Ｐｍｉｎ）、この並列電池Ｃ（Ｐｍｉｎ）の内部抵抗をＲ（Ｐｍｉｎ）と記す。
【００２３】
４．並列電池Ｃ（Ｐｍｉｎ）を構成する単電池の中で最も大きい内部抵抗ＲＣｍａｘを推定ＣＰＵ１０２は、抽出した並列電池Ｃ（Ｐｍｉｎ）を構成する単電池のうち、１つの単電池のみが他の単電池に比べて内部抵抗が大きくなったと仮定する。つまり、単電池Ｃ１〜Ｃ８の８つの単電池で組電池を構成する場合を例にとれば、１つの単電池が劣化してその内部抵抗ＲＣｍａｘが上昇し、他の７つの単電池の内部抵抗は同一の正常値をとることを想定する。並列電池Ｃ（Ｐｍｉｎ）の内部抵抗Ｒ（Ｐｍｉｎ）は、次式（３）で与えられる。
【数３】
Ｒ（Ｐｍｉｎ）＝（ＲＣｍａｘ×ＲＣａｖｅ（ｎ−１））／（ＲＣｍａｘ＋（ｎ−１）×ＲＣａｖｅ）　　（３）
ただし、ＲＣａｖｅは正常な単電池の内部抵抗の平均値である。ｎは並列電池を構成する単電池の数である。図１の例ではｎ＝２である。
【００２４】
各単電池の内部抵抗の平均値ＲＣａｖｅは、次式（４）で与えられる。
【数４】
Ｒ（Ｐ）ａｖｅ＝ＲＣａｖｅｎ／（ｎ×ＲＣａｖｅ）　　　　　　　　　　　　（４）
ただし、Ｒ（Ｐ）ａｖｅは、並列電池Ｃ（Ｐｍｉｎ）以外の並列電池Ｃ（Ｐ）の内部抵抗Ｒ（Ｐ）の平均値である。ｎは並列電池を構成する単電池の数である。
【００２５】
ＣＰＵ１０２は、並列電池Ｃ（Ｐｍｉｎ）以外の並列電池Ｃ（Ｐ）の内部抵抗Ｒ（Ｐ）をそれぞれ求め、これら内部抵抗Ｒ（Ｐ）の平均値を算出して上式（４）の左辺に代入し、単電池の内部抵抗の平均値ＲＣａｖｅを算出する。算出した平均値ＲＣａｖｅをさらに上式（３）へ代入し、内部抵抗ＲＣｍａｘを算出する。
【００２６】
５．内部抵抗ＲＣｍａｘと他の単電池の内部抵抗ＲＣａｖｅとの比の算出
ＣＰＵ１０２は、ＲＣｍａｘ／ＲＣａｖｅを算出する。ＲＣｍａｘ／ＲＣａｖｅを内部抵抗最大セル比（Ｒ（Ｐｍｉｎ）ｒａｔｉｏ）と呼ぶ。
【００２７】
６．組電池の最大放電電力の算出
ＣＰＵ１０２は、次式（５）により組電池の最大放電電力ＰＭＡＸを算出する。
【数５】
ＰＭＡＸ
＝Ｖｍｉｎ（Ｐ）×（Ｅ０（Ｐｍｉｎ）×ｍ−Ｖｍｉｎ（Ｐ））／（Ｒ（Ｐ）ａｖｅ×ｍ×Ｒ（Ｐｍｉｎ）ｒａｔｉｏ）　（５）
ただし、Ｖｍｉｎ（Ｐ）は、並列電池の放電停止電圧である。Ｅ０（Ｐｍｉｎ）は、並列電池Ｃ（Ｐｍｉｎ）の開放電圧である。ｍは並列電池の組数である。図１の例ではｍ＝４である。Ｒ（Ｐ）ａｖｅは、並列電池Ｃ（Ｐｍｉｎ）以外の並列電池Ｃ（Ｐ）の内部抵抗Ｒ（Ｐ）の平均値である。Ｒ（Ｐｍｉｎ）ｒａｔｉｏは、内部抵抗最大セル比である。
【００２８】
ＣＰＵ１０２は、最大充電電力の演算を以下の手順で行う。
▲１▼並列電池ごとに端子電圧および電流を測定する。
▲２▼並列電池ごとに最大充電電力を算出する。
▲３▼最大充電電力が最小のものを抽出する。
▲４▼抽出した並列電池を構成する単電池の中で最も大きい内部抵抗ＲＣｍａｘを推定する。
▲５▼内部抵抗ＲＣｍａｘと、他の単電池の内部抵抗ＲＣａｖｅとの比を算出する。
▲６▼組電池の最大充電電力を算出する。
このうち、▲１▼、▲４▼および▲５▼は上述した最大放電電力の演算の場合と同様であるので説明を省略する。
【００２９】
２．並列電池ごとの最大放電電力の算出
図２において、回帰直線と充電時の許容最大電圧Ｖｍａｘ（Ｐ）との交点Ａの電流ＩＣｍａｘ（Ｐ）は、並列電池の最大充電電流を与える。ＣＰＵ１０２は、並列電池の最大充電電力ＰＣｍａｘを次式（６）で算出する。
【数６】
Figure 2004031014
【００３０】
３．最大充電電力が最小の並列電池を抽出
ＣＰＵ１０２は、上述したように算出した４組の並列電池Ｃ（Ｐ１）〜Ｃ（Ｐ４）の最大充電電力ＰＣｍａｘ（Ｐ１）、ＰＣｍａｘ（Ｐ２）、ＰＣｍａｘ（Ｐ３）、ＰＣｍａｘ（Ｐ４）の中で、最小値のものを抽出する。以後、抽出した最小値をＰＣｍａｘ（Ｐｍｉｎ）と記す。また、ＰＣｍａｘ（Ｐｍｉｎ）に対応する並列電池をＣ（Ｐｍｉｎ）、この並列電池Ｃ（Ｐｍｉｎ）の内部抵抗をＲ（Ｐｍｉｎ）と記す。
【００３１】
６．組電池の最大充電電力の算出
ＣＰＵ１０２は、次式（７）により組電池の最大充電電力ＰＣＭＡＸを算出する。
【数７】
ＰＣＭＡＸ
＝Ｖｍａｘ（Ｐ）×（Ｅ０（Ｐｍｉｎ）×ｍ−Ｖｍａｘ（Ｐ））／（Ｒ（Ｐ）ａｖｅ×ｍ×Ｒ（Ｐｍｉｎ）ｒａｔｉｏ）（７）
ただし、Ｖｍａｘ（Ｐ）は、並列電池の許容最大電圧である。Ｅ０（Ｐｍｉｎ）は、並列電池Ｃ（Ｐｍｉｎ）の開放電圧である。ｍは並列電池の組数である。Ｒ（Ｐ）ａｖｅは、並列電池Ｃ（Ｐｍｉｎ）以外の並列電池Ｃ（Ｐ）の内部抵抗Ｒ（Ｐ）の平均値である。Ｒ（Ｐｍｉｎ）ｒａｔｉｏは、内部抵抗最大セル比である。
【００３２】
以上説明した実施の形態についてまとめる。
（１）単電池Ｃ１およびＣ２を並列に接続した並列電池Ｃ（Ｐ１）と、単電池Ｃ３およびＣ４を並列に接続した並列電池Ｃ（Ｐ２）と、単電池Ｃ５およびＣ６を並列に接続した並列電池Ｃ（Ｐ３）と、単電池Ｃ７およびＣ８を並列に接続した並列電池Ｃ（Ｐ４）とをそれぞれ直列に接続して組電池を構成する。
（２）上記組電池に流れる電流を電流センサ２０１で検出し、上記組電池を構成するそれぞれの並列電池の端子電圧をセル電圧検出部１０１で検出する。ＣＰＵ１０２は、直線回帰演算により並列電池ごとに最大放電電力Ｐｍａｘ（Ｐ）および最大充電電力ＰＣｍａｘ（Ｐ）を算出する。
【００３３】
（３）組電池としての最大放電電力ＰＭＡＸを算出するとき、並列電池ごとの最大放電電力Ｐｍａｘ（Ｐ）が最小の並列電池を選び、この並列電池Ｃ（Ｐｍｉｎ）の放電電力に応じて組電池としての最大放電電力ＰＭＡＸを算出するようにした。並列電池Ｃ（Ｐｍｉｎ）の内部抵抗Ｒ（Ｐ）は、組電池を構成する並列電池の中で最大である。並列電池の最大放電電力Ｐｍａｘ（Ｐ）が最小Ｐｍａｘ（Ｐｍｉｎ）の並列電池に着目して算出することにより、いずれの並列電池でも電池電圧が下限値を下回らないように適切な領域で電池を使用することができ、電池の劣化を防止することができる。
【００３４】
（４）上記並列電池Ｃ（Ｐｍｉｎ）について、当該並列電池を構成する単電池のうち１つの単電池の内部抵抗が他の単電池の内部抵抗に比べて上昇して最大値ＲＣｍａｘを有し、他の単電池の内部抵抗が同一の正常値をとると仮定して内部抵抗最大セル比ＲＣｍａｘ／ＲＣａｖｅを算出するようにした。ＲＣａｖｅは、並列電池Ｃ（Ｐｍｉｎ）以外の並列電池の内部抵抗Ｒ（Ｐ）から算出した他の単電池の内部抵抗である。内部抵抗最大セル比を用いて組電池の最大放電電力ＰＭＡＸを算出するので、並列電池を構成する単電池の容量が低い方の電池に応じた放電制限値を得ることができる。さらに、並列電池Ｃ（Ｐｍｉｎ）を構成する単電池のうち１つの単電池の内部抵抗が上昇して最大値ＲＣｍａｘをとる仮定をしたので、内部抵抗の最悪値を想定して最大放電電力を算出できる。この結果、組電池を構成するいずれの単電池でも電池電圧が下限値を下回らないように適切な領域で電池を使用することができ、電池の劣化を防止できる。
【００３５】
上記（４）について補足説明する。図３は、２つの単電池Ｖ１およびＶ２が並列に接続された並列電池を示す図である。この並列電池に負荷を接続すると、並列電池は電流Ｉを負荷へ流す。セル電圧検出部１０１は、負荷時の端子電圧Ｖを検出する。単電池Ｖ１のＳＯＣ（充電状態）が単電池Ｖ２のＳＯＣより高く、単電池Ｖ１から単電池Ｖ２側へ容量調整電流が流れる状態では、単電池Ｖ１の電流Ｉ１の一部が単電池Ｖ２側へ流れる。並列電池の中で単電池の電圧のばらつきに起因して電圧が高い側の電池から電圧が低い側の電池へ調整電流が流れる場合、２つの単電池の開放電圧は異なる値をとる。図４は、時間の経過とともにセル電圧検出部１０１で検出される端子電圧、および各単電池の開放電圧を示す図である。図４において、横軸は時間を表し、縦軸は電圧を表す。曲線Ｖは並列電池の端子電圧を、曲線Ｅ０１は単電池Ｖ１の開放電圧を、曲線Ｅ０２は単電池Ｖ２の開放電圧をそれぞれ示す。図４は、並列電池の端子電圧Ｖが電池使用時の電圧下限値を下回らない状態でも、単電池Ｖ２の開放電圧が電圧下限値より低くなる場合があることを示している。本発明による演算方法は、並列電池のうち電池電圧が低い方の単電池の電池電圧が下限値を下回らないように最大放電電力を演算するものである。
【００３６】
（５）組電池としての最大充電電力ＰＣＭＡＸを算出するとき、並列電池ごとの最大充電電力ＰＣｍａｘ（Ｐ）が最小の並列電池を選び、この並列電池Ｃ（Ｐｍｉｎ）の充電電力に応じて組電池としての最大充電電力ＰＣＭＡＸを算出するようにした。並列電池Ｃ（Ｐｍｉｎ）の内部抵抗Ｒ（Ｐ）は、組電池を構成する並列電池の中で最大である。並列電池の最大充電電力ＰＣｍａｘ（Ｐ）が最小ＰＣｍａｘ（Ｐｍｉｎ）の並列電池に着目して算出することにより、いずれの並列電池でも電池電圧が上限値を上回らないように適切な領域で電池を使用することができ、電池の劣化を防止することができる。
【００３７】
（６）上記並列電池Ｃ（Ｐｍｉｎ）について、上記（４）と同様に内部抵抗最大セル比ＲＣｍａｘ／ＲＣａｖｅを算出するようにした。内部抵抗最大セル比を用いて組電池の最大充電電力ＰＣＭＡＸを算出するので、並列電池を構成する単電池の容量が低い方の電池に応じた充電制限値を得ることができる。さらに、並列電池Ｃ（Ｐｍｉｎ）を構成する単電池のうち１つの単電池の内部抵抗が上昇して最大値ＲＣｍａｘをとる仮定をしたので、内部抵抗の最悪値を想定して最大充電電力を算出できる。この結果、組電池を構成するいずれの単電池でも電池電圧が上限値を上回らないように適切な領域で電池を使用することができ、電池の劣化を防止できる。
【００３８】
上記の説明で用いた並列電池を構成する単電池の数ｎ、および直列接続した並列電池の数ｍは、上述した例に限らず適宜設定してよい。
【００３９】
特許請求の範囲における各構成要素と、発明の実施の形態における各構成要素との対応について説明する。組電池は、たとえば、単電池Ｃ１〜Ｃ８によって構成される。並列接続電池は、たとえば、単電池Ｃ１およびＣ２を並列に接続した並列電池Ｃ（Ｐ１）、単電池Ｃ３およびＣ４を並列に接続した並列電池Ｃ（Ｐ２）、単電池Ｃ５およびＣ６を並列に接続した並列電池Ｃ（Ｐ３）、および単電池Ｃ７およびＣ８を並列に接続した並列電池Ｃ（Ｐ４）によって構成される。また、電圧センサ２０２が電圧検出手段を、電流センサ２０１が電流検出手段を、ＣＰＵ１０２が内部抵抗算出手段、抽出手段、推定手段、および最大充放電電力演算手段をそれぞれ構成する。なお、本発明の特徴的な機能を損なわない限り、各構成要素は上記構成に限定されるものではない。
【図面の簡単な説明】
【図１】本発明による方法で組電池の充放電電力を演算する制御ユニットを搭載した車両の全体構成図である。
【図２】回帰直線を説明する図である。
【図３】２つの単電池が並列に接続された並列電池を示す図である。
【図４】並列電池の端子電圧および各単電池の開放電圧を示す図である。
【符号の説明】
１０１…セル電圧検出部、　　　　　　１０２…ＣＰＵ、
１０３…メモリ、　　　　　　　　　　２０１…電流センサ、
３０４…車両システムＣＰＵ、　　　　Ｃ１〜Ｃ８…単電池[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for calculating the maximum charge / discharge power of a battery pack including batteries connected in parallel.
[0002]
[Prior art]
2. Description of the Related Art A technology for driving a load using a rechargeable secondary battery as a power source, such as an electric vehicle, is known. The battery repeatedly performs a discharging operation for driving the load and a charging operation for charging the battery. The discharge power and the charge power of such a battery are controlled so as to be equal to or less than the maximum discharge power and the maximum charge power, respectively. As a method of calculating the maximum discharge power and the maximum charge power, there has been proposed a method of performing a linear regression calculation of the IV characteristic based on the terminal voltage V and the discharge current I measured during discharging of the battery (for example, see Japanese Patent Application Laid-Open No. H9-1997). No. 218251). Generally, in a lithium ion battery or a nickel hydride battery, when the depth of discharge (DOD) of the battery is within a predetermined region (for example, 0 to 60%), the internal resistance at the time of charging and the internal resistance at the time of discharging substantially match, and Good linearity of IV characteristics. Therefore, the terminal voltage V measured during battery discharge is plotted on the vertical axis, and the discharge current I is plotted on the horizontal axis, and a regression line is obtained from the obtained IV characteristics. When this regression line is extended to the discharge-side region and the charge-side region, the V-axis intercept represents the open circuit voltage of the battery. The maximum discharge power is given by the product of the current Imax indicated by the intersection of the regression line and the discharge stop voltage Vmin during discharge, and the discharge stop voltage Vmin. On the other hand, the maximum charging power is given by the product of the current Imax indicated by the intersection of the regression line and the allowable maximum voltage Vmax and the allowable maximum voltage Vmax.
[0003]
[Problems to be solved by the invention]
There is a demand to use a battery in which a plurality of secondary cells are connected in parallel for the power supply. When batteries are connected in parallel, current flows from the battery with the higher voltage to the battery with the lower voltage. This current is called an adjustment current and flows so as to match the terminal voltage between the batteries. Therefore, even if the terminal voltage of a parallel battery in which cells are connected in parallel is measured, the actual open-circuit voltage of each cell is not known.In the conventional method, the maximum discharge power and the maximum It is difficult to find the charging power.
[0004]
An object of the present invention is to calculate the maximum charge / discharge power of a battery pack including a parallel-connected battery that calculates at least one of the maximum discharge power and the maximum charge power for using a secondary cell connected in parallel in an appropriate region. It is to provide a method and an apparatus.
[0005]
[Means for Solving the Problems]
The present invention relates to a method of calculating the maximum charge / discharge power of an assembled battery in which a plurality of secondary cells are connected in parallel and a plurality of secondary cells are connected in parallel, and a voltage value for each of the parallel batteries when the assembled battery is discharged, and The internal resistance is calculated for each parallel battery from the characteristics of the current value of the assembled battery at the time of discharging, and the maximum value of the calculated internal resistance and the internal resistance values of the parallel batteries other than the parallel battery corresponding to the maximum value are calculated as described above. The maximum value of the internal resistance of the unit cell constituting the parallel battery having the maximum internal resistance is estimated, and at least one of the maximum discharge power and the maximum charge power is calculated according to the estimated maximum value of the internal resistance. Things.
[0006]
Further, the present invention relates to a maximum charge / discharge power calculating device for a battery pack including a parallel-connected battery, wherein a plurality of secondary cells are connected in parallel, and when the battery pack having a plurality of the parallel batteries connected in series is discharged, the parallel battery is discharged. In addition to detecting the voltage of each battery, when discharging the assembled battery, the current flowing through the assembled battery is detected, and based on the detected voltage and current, the internal resistance of each of the parallel batteries is calculated. The maximum parallel battery is extracted, and the internal resistance of the unit cell constituting the extracted parallel battery is determined using the internal resistance of the extracted parallel battery and the internal resistance of the parallel battery other than the extracted parallel battery. Is estimated, and at least one of the maximum discharge power and the maximum charge power of the battery pack is calculated according to the estimated maximum value of the internal resistance.
[0007]
【The invention's effect】
When the maximum charge / discharge power of the battery pack including the parallel-connected batteries is calculated in the present invention, the unit cells of the parallel batteries constituting the battery pack can be used in an appropriate region, so that the deterioration of the battery can be prevented.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram of a vehicle equipped with a control unit for calculating charge / discharge power of a battery pack by a method according to the present invention. In the following embodiment, an example in which the assembled battery is applied as a power source of an electric vehicle will be described. In FIG. 1, the vehicle control system includes a vehicle system and a battery control unit. The thick solid line in the figure represents a high-voltage line (high-voltage wiring), and the normal solid line represents a low-voltage line (low-voltage wiring). Dashed lines indicate signal lines transmitted and received between each block.
[0009]
The vehicle system includes a current sensor 201, a voltage sensor 202, a temperature sensor 203, a driving motor 301, an auxiliary system 302, and main relays 303A and 303B. The assembled battery includes secondary cells (cells) C1 to C8. The cells C1 and C2, the cells C3 and C4, the cells C5 and C6, and the cells C7 and C8 are connected in parallel, respectively. In the battery pack, these four parallel batteries (C1, C2), parallel batteries (C3, C4), parallel batteries (C5, C6), and parallel batteries (C7, C8) are connected in series. The battery control unit has a cell voltage detection unit 101, a CPU 102, and a memory 103.
[0010]
The driving motor 301 is driven by the DC power of the battery pack being supplied as AC power via an inverter (not shown) to generate driving force of the vehicle and generate regenerative power for the battery pack. The auxiliary system 302 drives an air conditioner (A / C) (not shown) mounted on the vehicle with electric power supplied from the battery pack. The main relays 303 </ b> A and 303 </ b> B are controlled to open and close according to a command from the CPU 102, and turn on / off power supply to the drive motor 301 and the auxiliary system 302.
[0011]
The current sensor 201 detects a current flowing through a high-voltage line (= assembled battery) and sends a detection signal to the CPU 102. Voltage sensor 202 detects the voltage (total voltage) of the assembled battery and sends a detection signal to CPU 102. Temperature sensor 203 detects the temperature of the battery pack and sends a temperature detection signal to CPU 102.
[0012]
The cell voltage detection unit 101 includes a terminal voltage of the parallel batteries (C1, C2), a terminal voltage of the parallel batteries (C3, C4), a terminal voltage of the parallel batteries (C5, C6), and a terminal voltage of the parallel batteries (C7, C8). , And sends out four sets of voltage information to the CPU 102. The CPU 102 calculates the maximum charging power during charging (regeneration) and the maximum discharging power during discharging using the voltage information of the four parallel batteries. The calculation of the maximum charge / discharge power is performed when the vehicle is running (when the IGN switch is on) and when the battery pack is charged. The calculation result of the maximum charge / discharge power is transmitted from CPU 102 to vehicle system CPU 304. Further, when the temperature of the battery pack is abnormal, the CPU 102 notifies the vehicle system CPU 304 of the abnormal temperature.
[0013]
The memory 103 stores the voltage information of the four sets of parallel batteries and the current information of the high-power lines (= assembled batteries) input to the CPU 102.
[0014]
Vehicle system CPU 304 controls the vehicle system by limiting the power output from the assembled battery so that the power output to drive motor 301 and accessory system 302 is equal to or less than the maximum discharge power received from CPU 102. Further, vehicle system CPU 304 controls the vehicle system by limiting the power for charging the assembled battery so that the power regenerated from drive motor 301 is equal to or less than the maximum charging power received from CPU 102. The vehicle warning light 305 is turned on by a command from the vehicle system CPU 304 to notify the driver of the occurrence of an abnormality in the vehicle system. The auxiliary battery 401 supplies power to the CPU 102 and the vehicle system CPU 304. The switch SW turns on / off power supply from the auxiliary battery 401 in conjunction with turning on / off of an ignition (IGN) switch 402 by the driver.
[0015]
The present invention is characterized by a method of calculating the maximum discharge power at the time of discharging and the maximum charging power at the time of charging (regeneration) of the battery pack.
[0016]
The CPU 102 calculates the maximum discharge power according to the following procedure.
(1) Measure the terminal voltage and current for each parallel battery.
(2) Calculate the maximum discharge power for each parallel battery.
{Circle around (3)} The one with the smallest maximum discharge power is extracted.
{Circle around (4)} Estimate the largest internal resistance R C max among the cells constituting the extracted parallel battery.
(5) Calculate the ratio of the internal resistance R C max to the internal resistance R C ave of another unit cell.
(6) Calculate the maximum discharge power of the battery pack.
[0017]
1. The CPU 102 measures the terminal voltage and current for each parallel battery. The CPU 102 detects four sets of parallel batteries C (P 1 ) (consisting of the cells C1 and C2), a cell C (P 2 ) (cell C3) And C4), information indicating the terminal voltages of the parallel battery C (P 3 ) (comprising the cells C5 and C6), and the parallel battery C (P 4 ) (comprising the cells C7 and C8), respectively. At the same time, information indicating the current of the high-power line is input from the current sensor 201. The current value flowing through the high-power line is equal to the current value of each parallel battery (for example, the total current value of the current value flowing through the cell C1 and the current value flowing through the cell C2).
[0018]
2. Calculation of Maximum Discharge Power for Each Parallel Battery The CPU 102 performs a linear regression calculation of the IV characteristic for each parallel battery using the voltage value indicated by the voltage information obtained by a plurality of measurements during discharging and the current value indicated by the current information. I do. FIG. 2 is a diagram for explaining a regression line, which is obtained from the measured data of the current I and the voltage V of the parallel battery being discharged. For batteries such as lithium-ion batteries or nickel-metal hydride batteries, the internal resistance of the battery is almost the same during charging and discharging, and the IV characteristics during charging and discharging have good linearity. The regression line can be extended to the charging side. The crosses in the figure represent measurement data.
[0019]
The regression line in FIG. 2 can be expressed by the following equation (1).
(Equation 1)
V (P) = E 0 (P) −I × R (P) (1)
Here, V (P) is the terminal voltage of the parallel battery, the V-axis intercept E 0 (P) is the open voltage of the parallel battery, and the slope R (P) of the regression line is the internal resistance of the parallel battery.
[0020]
In the present embodiment, the open-circuit voltage E 0 (P) of the parallel battery is estimated by a regression line. There is also a method of measuring the voltage at no load to obtain an open circuit voltage.However, a battery with good linearity of charge-discharge IV characteristics has a good match between the estimated open circuit voltage and the actual open circuit voltage. Estimate using IV characteristics.
[0021]
In FIG. 2, the current Imax (P) at the intersection B between the regression line and the discharge stop voltage Vmin (P) during discharging is the maximum discharge current of the parallel battery. The maximum discharge power Pmax (P) of the parallel battery is calculated by the following equation (2) using the above equation (1).
(Equation 2)
Figure 2004031014
[0022]
3. The CPU 102 extracts the parallel battery with the minimum maximum discharge power. The CPU 102 calculates the maximum discharge power Pmax (P 1 ), Pmax (P 2 ) of the four parallel batteries C (P 1 ) to C (P 4 ) calculated as described above. , Pmax (P 3 ) and Pmax (P 4 ) are extracted. Hereinafter, the extracted minimum value is referred to as Pmax (Pmin). The parallel battery corresponding to Pmax (Pmin) is denoted by C (Pmin), and the internal resistance of this parallel battery C (Pmin) is denoted by R (Pmin).
[0023]
4. The CPU 102 estimates the largest internal resistance R C max among the cells constituting the parallel battery C (Pmin). The CPU 102 determines that only one cell among the extracted cells constituting the parallel battery C (Pmin) is the other. Assume that the internal resistance is higher than that of a single cell. That is, in the case where the battery pack is composed of eight cells C1 to C8 as an example, one cell deteriorates, its internal resistance R C max increases, and the cells of the other seven cells C1 to C8 increase. It is assumed that the internal resistance takes the same normal value. The internal resistance R (Pmin) of the parallel battery C (Pmin) is given by the following equation (3).
[Equation 3]
R (Pmin) = ( RC max × RC cave (n−1) ) / ( RC max + (n−1) × RC cave) (3)
However, R C ave is the average value of the internal resistance of the normal unit cells. n is the number of cells constituting the parallel battery. In the example of FIG. 1, n = 2.
[0024]
Mean value R C ave of the internal resistance of each cell is given by the following equation (4).
(Equation 4)
R (P) ave = R C ave n / (n × R C ave) (4)
Here, R (P) ave is the average value of the internal resistance R (P) of the parallel batteries C (P) other than the parallel battery C (Pmin). n is the number of cells constituting the parallel battery.
[0025]
The CPU 102 calculates the internal resistance R (P) of each of the parallel batteries C (P) other than the parallel battery C (Pmin), calculates the average value of these internal resistances R (P), and calculates Then, the average value R C ave of the internal resistance of the cell is calculated. The calculated average value R C ave is further substituted into the above equation (3) to calculate the internal resistance R C max.
[0026]
5. Calculation of ratio of internal resistance R C max to internal resistance R C ave of another unit cell CPU 102 calculates R C max / R C ave. R C max / R C ave is referred to as a maximum internal resistance cell ratio (R (Pmin) ratio).
[0027]
6. Calculation of maximum discharge power of battery pack The CPU 102 calculates the maximum discharge power PMAX of the battery pack by the following equation (5).
(Equation 5)
PMAX
= Vmin (P) × (E 0 (Pmin) × m−Vmin (P)) / (R (P) ave × m × R (Pmin) ratio) (5)
Here, Vmin (P) is the discharge stop voltage of the parallel battery. E 0 (Pmin) is the open circuit voltage of the parallel battery C (Pmin). m is the number of sets of parallel batteries. In the example of FIG. 1, m = 4. R (P) ave is the average value of the internal resistance R (P) of the parallel batteries C (P) other than the parallel battery C (Pmin). R (Pmin) ratio is the internal resistance maximum cell ratio.
[0028]
The CPU 102 calculates the maximum charging power in the following procedure.
(1) Measure the terminal voltage and current for each parallel battery.
(2) Calculate the maximum charging power for each parallel battery.
{Circle around (3)} The one with the smallest maximum charging power is extracted.
{Circle around (4)} Estimate the largest internal resistance R C max among the cells constituting the extracted parallel battery.
(5) Calculate the ratio of the internal resistance R C max to the internal resistance R C ave of another unit cell.
(6) Calculate the maximum charging power of the battery pack.
Among them, (1), (4), and (5) are the same as those in the case of the above-described calculation of the maximum discharge power, and thus the description is omitted.
[0029]
2. Calculation of Maximum Discharge Power for Each Parallel Battery In FIG. 2, the current ICmax (P) at the intersection A between the regression line and the allowable maximum voltage Vmax (P) during charging gives the maximum charging current of the parallel batteries. The CPU 102 calculates the maximum charging power PCmax of the parallel battery by the following equation (6).
(Equation 6)
Figure 2004031014
[0030]
3. Maximum extraction charging power is minimum of the parallel battery CPU102, the maximum charging power PCmax four sets of parallel cell C calculated as described above (P 1) ~C (P 4 ) (P 1), PCmax (P 2) , PCmax (P 3 ) and PCmax (P 4 ) are extracted. Hereinafter, the extracted minimum value is referred to as PCmax (Pmin). The parallel battery corresponding to PCmax (Pmin) is denoted by C (Pmin), and the internal resistance of this parallel battery C (Pmin) is denoted by R (Pmin).
[0031]
6. Calculation of Maximum Charge Power of Battery Assembly The CPU 102 calculates the maximum charge power PCMAX of the battery assembly by the following equation (7).
(Equation 7)
PCMAX
= Vmax (P) × (E 0 (Pmin) × m−Vmax (P)) / (R (P) ave × m × R (Pmin) ratio) (7)
Here, Vmax (P) is the allowable maximum voltage of the parallel battery. E 0 (Pmin) is the open circuit voltage of the parallel battery C (Pmin). m is the number of sets of parallel batteries. R (P) ave is the average value of the internal resistance R (P) of the parallel batteries C (P) other than the parallel battery C (Pmin). R (Pmin) ratio is the internal resistance maximum cell ratio.
[0032]
The embodiments described above are summarized.
(1) connected to the single batteries C1 and C2 parallel cell C connected in parallel (P 1), and unit cell C3 and C4 the parallel battery C connected in parallel (P 2), the unit cells C5 and C6 in parallel The assembled parallel battery C (P 3 ) and the parallel battery C (P 4 ) in which the unit cells C7 and C8 are connected in parallel are connected in series to form an assembled battery.
(2) The current flowing through the battery pack is detected by the current sensor 201, and the terminal voltage of each parallel battery constituting the battery pack is detected by the cell voltage detection unit 101. The CPU 102 calculates the maximum discharge power Pmax (P) and the maximum charge power PCmax (P) for each parallel battery by a linear regression calculation.
[0033]
(3) When calculating the maximum discharge power PMAX of the battery pack, a parallel battery with the minimum maximum discharge power Pmax (P) for each parallel battery is selected, and the battery pack is selected according to the discharge power of the parallel battery C (Pmin). Is calculated as the maximum discharge power PMAX. The internal resistance R (P) of the parallel battery C (Pmin) is the largest among the parallel batteries constituting the assembled battery. By calculating by paying attention to the parallel battery having the maximum discharge power Pmax (P) of the parallel battery being the minimum Pmax (Pmin), the battery is used in an appropriate region so that the battery voltage does not fall below the lower limit value in any of the parallel batteries. And the deterioration of the battery can be prevented.
[0034]
(4) Regarding the parallel battery C (Pmin), the internal resistance of one of the cells constituting the parallel battery increases relative to the internal resistance of the other cells, and has a maximum value R C max. Then, assuming that the internal resistances of the other cells take the same normal value, the internal resistance maximum cell ratio RC max / RC ave is calculated. R C ave is an internal resistance of the other unit cell which is calculated from the internal resistance R (P) in parallel batteries other than parallel cell C (Pmin). Since the maximum discharge power PMAX of the assembled battery is calculated using the internal resistance maximum cell ratio, it is possible to obtain a discharge limit value corresponding to the battery having a lower capacity of the unit cells constituting the parallel battery. Furthermore, since it was assumed that the internal resistance of one of the cells constituting the parallel battery C (Pmin) increases and takes the maximum value R C max, the maximum discharge power is assumed assuming the worst value of the internal resistance. Can be calculated. As a result, the battery can be used in an appropriate region so that the battery voltage does not fall below the lower limit value of any of the cells constituting the assembled battery, and the deterioration of the battery can be prevented.
[0035]
The above (4) will be supplementarily described. FIG. 3 is a diagram illustrating a parallel battery in which two unit cells V1 and V2 are connected in parallel. When a load is connected to the parallel battery, the parallel battery passes a current I to the load. The cell voltage detection unit 101 detects a terminal voltage V under load. In a state where the SOC (charging state) of the cell V1 is higher than the SOC of the cell V2 and a capacity adjustment current flows from the cell V1 to the cell V2, a part of the current I1 of the cell V1 flows to the cell V2. Flows. When the adjustment current flows from the battery with the higher voltage to the battery with the lower voltage due to the variation in the voltage of the cells in the parallel cells, the open voltages of the two cells take different values. FIG. 4 is a diagram illustrating the terminal voltage detected by the cell voltage detection unit 101 over time and the open-circuit voltage of each cell. In FIG. 4, the horizontal axis represents time, and the vertical axis represents voltage. The curve V indicates the terminal voltage of the parallel battery, the curve E01 indicates the open voltage of the cell V1, and the curve E02 indicates the open voltage of the cell V2. FIG. 4 shows that even when the terminal voltage V of the parallel battery does not fall below the voltage lower limit when the battery is used, the open-circuit voltage of the unit cell V2 may be lower than the voltage lower limit. The calculation method according to the present invention calculates the maximum discharge power so that the battery voltage of the unit cell having the lower battery voltage among the parallel batteries does not fall below the lower limit.
[0036]
(5) When calculating the maximum charging power PCMAX as a battery pack, a parallel battery having the minimum maximum charging power PCmax (P) for each parallel battery is selected, and the battery pack is selected according to the charging power of this parallel battery C (Pmin). Is calculated as the maximum charging power PCMAX. The internal resistance R (P) of the parallel battery C (Pmin) is the largest among the parallel batteries constituting the assembled battery. By calculating by paying attention to the parallel battery with the maximum charging power PCmax (P) of the parallel battery being the minimum PCmax (Pmin), the battery is used in an appropriate region so that the battery voltage does not exceed the upper limit value in any of the parallel batteries. And the deterioration of the battery can be prevented.
[0037]
(6) With respect to the parallel battery C (Pmin), the maximum internal resistance cell ratio RC max / RC ave is calculated in the same manner as in (4). Since the maximum charge power PCMAX of the battery pack is calculated using the internal resistance maximum cell ratio, a charge limit value corresponding to the battery having the lower capacity of the unit cells constituting the parallel battery can be obtained. Further, since it is assumed that the internal resistance of one of the cells constituting the parallel battery C (Pmin) increases and takes the maximum value R C max, the maximum charging power is assumed assuming the worst value of the internal resistance. Can be calculated. As a result, the battery can be used in an appropriate region so that the battery voltage does not exceed the upper limit value in any of the cells constituting the assembled battery, and the deterioration of the battery can be prevented.
[0038]
The number n of unit cells constituting the parallel battery and the number m of parallel batteries connected in series used in the above description are not limited to the above-described example, and may be set as appropriate.
[0039]
Correspondence between each component in the claims and each component in the embodiment of the invention will be described. The assembled battery includes, for example, the cells C1 to C8. Parallel connection cells, for example, parallel cell C (P 1) connected single cells C1 and C2 in parallel, the parallel batteries C (P 2) of the unit cells C3 and C4 are connected in parallel, parallel single cells C5 and C6 It constituted by connecting in parallel cell C (P 3), and parallel battery C (P 4) of the unit cell C7 and C8 are connected in parallel to the. Further, the voltage sensor 202 constitutes a voltage detecting means, the current sensor 201 constitutes a current detecting means, and the CPU 102 constitutes an internal resistance calculating means, an extracting means, an estimating means, and a maximum charge / discharge power calculating means. Note that each component is not limited to the above configuration as long as the characteristic functions of the present invention are not impaired.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a vehicle equipped with a control unit for calculating charge / discharge power of a battery pack by a method according to the present invention.
FIG. 2 is a diagram illustrating a regression line.
FIG. 3 is a diagram showing a parallel battery in which two unit cells are connected in parallel.
FIG. 4 is a diagram showing a terminal voltage of a parallel battery and an open voltage of each cell.
[Explanation of symbols]
101: cell voltage detection unit, 102: CPU,
103: memory, 201: current sensor,
304: vehicle system CPU, C1 to C8: single cells

Claims (6)

複数の二次単電池を並列に接続し、前記並列電池を直列に複数接続した組電池の最大充放電電力を演算する方法であって、
前記組電池の放電時に前記並列電池ごとの電圧をそれぞれ検出し、
前記放電時に前記組電池を流れる電流を検出し、
前記検出した電流値および電圧値による特性から前記並列電池ごとに内部抵抗をそれぞれ算出し、
前記算出した内部抵抗が最大値を有する並列電池を抽出し、
前記抽出した並列電池の内部抵抗値、および前記抽出した並列電池以外の並列電池の内部抵抗値を用いて前記抽出した並列電池を構成する単電池の内部抵抗の最大値を推定し、
前記推定した内部抵抗の最大値に応じて最大放電電力と最大充電電力の少なくとも一方を算出することを特徴とする並列接続電池を含む組電池の最大充放電電力演算方法。A method of calculating the maximum charge / discharge power of an assembled battery in which a plurality of secondary cells are connected in parallel and the plurality of parallel batteries are connected in series,
Detecting the voltage of each of the parallel batteries at the time of discharging the battery pack,
Detecting the current flowing through the battery pack during the discharging,
The internal resistance is calculated for each of the parallel batteries from the characteristics based on the detected current value and voltage value,
The calculated internal resistance extracts the parallel battery having the maximum value,
The extracted internal resistance of the parallel battery, and the maximum value of the internal resistance of the unit cell constituting the extracted parallel battery using the internal resistance of the parallel battery other than the extracted parallel battery,
And calculating at least one of a maximum discharge power and a maximum charge power according to the estimated maximum value of the internal resistance. 請求項１に記載の組電池の最大充放電電力の演算方法において、
前記抽出した並列電池の検出電圧および前記検出した電流値による特性から当該並列電池の開放電圧を推定し、
前記最大放電電力の算出は、前記推定した開放電圧、前記並列電池の放電停止電圧、前記直列接続した前記並列電池の数、前記推定した内部抵抗の最大値、および前記並列電池ごとの内部抵抗の平均値を用いて算出することを特徴とする並列接続電池を含む組電池の最大充放電電力演算方法。The method for calculating the maximum charge / discharge power of a battery pack according to claim 1,
Estimate the open voltage of the parallel battery from the characteristics of the extracted parallel battery detection voltage and the detected current value,
The calculation of the maximum discharge power is performed based on the estimated open voltage, the discharge stop voltage of the parallel battery, the number of the parallel batteries connected in series, the maximum value of the estimated internal resistance, and the internal resistance of each parallel battery. A method for calculating the maximum charge / discharge power of a battery pack including a parallel-connected battery, wherein the method is calculated using an average value. 請求項１に記載の組電池の最大充放電電力の演算方法において、
前記抽出した並列電池の検出電圧および前記検出した電流値による特性から当該並列電池の開放電圧を推定し、
前記最大充電電力の算出は、前記推定した開放電圧、前記並列電池の最大許容電圧、前記直列接続した前記並列電池の数、前記推定した内部抵抗の最大値、および前記並列電池ごとの内部抵抗の平均値を用いて算出することを特徴とする並列接続電池を含む組電池の最大充放電電力演算方法。The method for calculating the maximum charge / discharge power of a battery pack according to claim 1,
Estimate the open voltage of the parallel battery from the characteristics of the extracted parallel battery detection voltage and the detected current value,
The calculation of the maximum charging power is performed based on the estimated open-circuit voltage, the maximum allowable voltage of the parallel battery, the number of the parallel batteries connected in series, the maximum value of the estimated internal resistance, and the internal resistance of each parallel battery. A method for calculating the maximum charge / discharge power of a battery pack including a parallel-connected battery, wherein the method is calculated using an average value. 請求項１〜３のいずれかに記載の組電池の最大充放電電力の演算方法において、
前記並列電池ごとの内部抵抗の算出および前記開放電圧の推定は、直線回帰演算を用いることを特徴とする並列接続電池を含む組電池の最大充放電電力演算方法。A method for calculating the maximum charge / discharge power of the battery pack according to any one of claims 1 to 3,
A method for calculating the maximum charge / discharge power of a battery pack including a parallel-connected battery, wherein the calculation of the internal resistance for each of the parallel batteries and the estimation of the open-circuit voltage use a linear regression calculation. 請求項１〜４のいずれかに記載の組電池の最大充放電電力の演算方法において、
前記抽出した並列電池を構成する単電池の内部抵抗の最大値の推定は、前記組電池を構成する全単電池のうち１つの単電池の内部抵抗が上昇し、前記１つの単電池以外は同一の内部抵抗値を有するとみなして行うことを特徴とする並列接続電池を含む組電池の最大充放電電力演算方法。The method for calculating the maximum charge / discharge power of an assembled battery according to any one of claims 1 to 4,
The estimation of the maximum value of the internal resistance of the cells constituting the extracted parallel battery is performed by estimating that the internal resistance of one cell among all the cells constituting the assembled battery rises, and the same except for the one cell. A method for calculating the maximum charge / discharge power of a battery pack including a parallel-connected battery, wherein the method is performed assuming that the internal resistance value has 複数の二次単電池を並列に接続し、前記並列電池を直列に複数接続した組電池と、
前記組電池の放電時に、前記並列電池ごとの電圧を検出する電圧検出手段と、
前記組電池の放電時に、前記組電池を流れる電流を検出する電流検出手段と、
前記電圧検出手段および前記電流検出手段により検出された電圧および電流に基づいて、前記並列電池ごとの内部抵抗を算出する内部抵抗算出手段と、
前記内部抵抗算出手段により算出された内部抵抗が最大の並列電池を抽出する抽出手段と、
前記抽出手段によって抽出された並列電池の内部抵抗と、前記抽出された並列電池以外の並列電池の内部抵抗とを用いて、前記抽出された並列電池を構成する単電池の内部抵抗の最大値を推定する推定手段と、
前記推定手段によって推定された内部抵抗の最大値に応じて、前記組電池の最大放電電力と最大充電電力の少なくとも一方を算出する最大充放電電力演算手段と、
を備えたことを特徴とする並列接続電池を含む組電池の最大充放電電力演算装置。A battery pack in which a plurality of secondary cells are connected in parallel, and a plurality of the parallel batteries are connected in series,
At the time of discharging the battery pack, voltage detecting means for detecting a voltage of each of the parallel batteries,
When the battery pack is discharged, current detection means for detecting a current flowing through the battery pack,
Based on the voltage and current detected by the voltage detecting means and the current detecting means, an internal resistance calculating means for calculating an internal resistance for each of the parallel batteries;
Extraction means for extracting a parallel battery having the maximum internal resistance calculated by the internal resistance calculation means,
Using the internal resistance of the parallel battery extracted by the extracting means and the internal resistance of the parallel battery other than the extracted parallel battery, the maximum value of the internal resistance of the unit cells constituting the extracted parallel battery is calculated. Estimating means for estimating,
Maximum charge / discharge power calculation means for calculating at least one of the maximum discharge power and the maximum charge power of the battery pack according to the maximum value of the internal resistance estimated by the estimation means,
A maximum charge / discharge power calculation device for a battery pack including a parallel-connected battery, comprising:
JP2002182920A 2002-06-24 2002-06-24 Method and apparatus for calculating maximum charge / discharge power of battery pack including parallel connected batteries Pending JP2004031014A (en)

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