JP4026337B2 - Control circuit - Google Patents
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- JP4026337B2 JP4026337B2 JP2001250996A JP2001250996A JP4026337B2 JP 4026337 B2 JP4026337 B2 JP 4026337B2 JP 2001250996 A JP2001250996 A JP 2001250996A JP 2001250996 A JP2001250996 A JP 2001250996A JP 4026337 B2 JP4026337 B2 JP 4026337B2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は制御回路に係り、特に、複数個のリチウム二次電池を直列に接続した組電池の制御回路に関する。
【０００２】
【従来の技術】
従来、直列にリチウム二次電池等の単電池が複数個直列に接続された組電池では、例えば、特開平１１−１１３１８２号公報に開示されているように、各単電池の電池電圧を差動増幅器により最下位−端子を基準に検出していた。このように、各単電池の電池電圧の検出が必要な理由は、組電池を構成するリチウム二次電池が充放電に伴って過充電、過放電に陥った場合に、組電池としての放電特性の低下、過充電での安全性の低下、過放電での寿命特性の低下等を招くためである。
【０００３】
図３に、このような電圧監視を行う従来の制御回路の構成例を示す。図３に示すように、組電池１は、８個のリチウム二次電池Ｂ１〜Ｂ８が直列に接続されている。各リチウム二次電池の電池電圧は、差動増幅器２を通じてマルチプレクサ３に入力され、マルチプレクサ３の出力はマイクロコンピュータ４のＡ／Ｄ変換に入力される。マイクロコンピュータ４はマルチプレクサ３の入力指定を出力ポートから指定し、マルチプレクサ３から入力された電圧をＡ／Ｄ変換し、各リチウム二次電池の電池電圧をデジタル値として測定する。また、マイクロコンピュータ４は、電池電圧の測定データについてフォトカプラ５を介して上位システムと通信を行う。
【０００４】
【発明が解決しようとする課題】
しかしながら、上述した従来の制御回路では、最下位−端子を基準に差動増幅器で各リチウム二次電池の電池電圧を検出していたので、入力電圧が高いほど差動増幅器の抵抗誤差の影響を受け、リチウム二次電池の直列数が多くなるほど、上位側のリチウム二次電池の電池電圧の検出誤差が大きくなる、という問題点があった。リチウム二次電池では、電圧検出の誤差は±数１０ｍＶ程度という高い精度が必要であり、精度を確保するため差動増幅器の抵抗に高精度の抵抗を用いるとコスト高となってしまう。
【０００５】
また、上位システムとの測定データの通信にフォトカプラを用いる場合には、フォトカプラはある程度の電流を通電しないと確実な信号伝送は行えない。特に、スパークノイズが発生する自動車に搭載される組電池又は複数個の組電池で構成される電池モジュールでは、フォトカプラに一定量の電流を流す必要があり、制御回路全体として消費電流が増加する傾向にある。消費電流を低減するために、マイクロコンピュータ等の半導体素子を低消費電力素子に変更することも可能であるが、コスト高となる、という問題点がある。
【０００６】
上記事案に鑑み本発明は、電圧検出精度が向上し、低コスト、かつ、低消費電流の制御回路を提供することを課題とする。
【０００７】
【課題を解決するための手段】
上記課題を解決するために、本発明は、複数個のリチウム二次電池を直列に接続した組電池の制御回路であって、正相入力端子が抵抗を介して前記組電池の任意の接続点と同電位となる仮想グランドに接続され、前記組電池を構成する各リチウム二次電池の＋端子の電圧を出力する差動増幅器を有するセル電圧変換回路と、前記仮想グランドを基準に前記各リチウム二次電池の電池電圧を測定する測定回路と、前記測定回路で測定した各リチウム二次電池の電池電圧を信号転送するためのフォトカプラと、を備え、前記仮想グランドは前記組電池の中点（前記組電池を構成するリチウム二次電池数ｎが偶数の場合：ｎ／２とｎ／２＋１番目のリチウム二次電池間、奇数の場合：（ｎ−１）／２と（ｎ＋１）／２番目のリチウム二次電池間）であり、前記セル電圧変換回路は前記組電池を構成するリチウム二次電池の最上位＋端子と最下位−端子とを作動電源とし、前記測定回路の作動電源は前記最上位＋端子と前記仮想グランドとの間から供給され、前記フォトカプラの主駆動電源が前記仮想グランドと前記最下位−端子との間から供給されることを特徴とする。
【０００８】
本発明は、セル電圧変換回路が差動増幅器を有して構成されており、セル電圧変換回路は、正相入力端子が抵抗を介して組電池の任意の接続点と同電位となる仮想グランドに接続されており、出力端子からは組電池を構成する各リチウム二次電池の＋端子の電圧が出力される。そして、測定回路により、仮想グランドを基準に各リチウム二次電池の電池電圧が測定され、フォトカプラにより測定回路で測定した各リチウム二次電池の電池電圧が信号転送される。本発明では、組電池の任意の接続点と同電位の仮想グランドを基準に各リチウム二次電池の電池電圧が測定されるので、セル電圧変換回路の差動増幅器の入力電圧が組電池の最下位−端子を基準とする場合より低く、電圧検出誤差が小さくなり、測定回路での各リチウム二次電池の電圧検出精度を向上させることができる。また、仮想グランドを組電池の中点としたので、各差動増幅器の同相入力電圧除去比を同一と仮定したときに、電圧検出誤差は組電池の最下位−端子を基準にする場合の半分となり、電圧検出精度を更に向上させることができ、電圧検出精度が向上することから差動増幅器に使用される抵抗の精度を一定以下に抑えることができるため、制御回路のコストを低減させることができる。さらに、セル電圧変換回路の作動電源を組電池を構成するリチウム二次電池の最上位＋端子と最下位−端子とし、測定回路の作動電源を最上位＋端子と仮想グランドとの間から供給し、フォトカプラの主駆動電源を仮想グランドと最下位−端子との間から供給するので、フォトカプラを仮想グランドと最下位−端子の間で駆動することでフォトカプラと測定回路とは直列接続され、消費電流を（フォトカプラ駆動電流＋測定回路電流）からフォトカプラ駆動電流と測定回路電流のいずれか大きい方の電流値まで低減させることができる。
【００１０】
【発明の実施の形態】
以下、図面を参照して、本発明が適用可能な制御回路の実施の形態について説明する。
【００１１】
図１に示すように、本実施形態の制御回路は、８個のリチウム二次電池Ｂ１〜Ｂ８が直列に接続された組電池１の各リチウム電池Ｂの電圧検出回路である。本制御回路は、各リチウム電池Ｂの数に対応した差動増幅器２を備えている。差動増幅器２は、ＯＰアンプと４本の抵抗とで構成されている。ＯＰアンプの正相入力端子には抵抗７１及び７２の一端が接続されており、抵抗７１の他端はリチウム二次電池Ｂ８の＋端子に接続されている。ＯＰアンプの逆相入力端子は抵抗７２及び７４の一端に接続されており、抵抗７２の他端はリチウム二次電池Ｂ８の−端子及び１つ下位の差動増幅器の正相入力端子に当該差動増幅器の抵抗７１を介して接続されている。
【００１２】
抵抗７３の他端は仮想グランドに接続されている。抵抗７４の他端はＯＰアンプの出力端子に接続されており、ＯＰアンプの出力端子はマルチプレクサ３に接続されている。また、差動増幅器２の正電源端子（ＶＣＣ）は最上位のリチウム二次電池Ｂ８の＋端子に接続されており、負電源端子（ＶＥＥ）は最下位のリチウム二次電池Ｂ１の−端子に接続されている。
【００１３】
下位の差動増幅器２は、最上位のリチウム二次電池Ｂ８に接続された差動増幅器２と同一の構成と接続とがなされているが、最下位のリチウム二次電池Ｂ１に接続された差動増幅器２は抵抗７２の他端が最下位のリチウム二次電池Ｂ１の−端子に接続されている点で異なっている。
【００１４】
組電池１の中点は、リチウム二次電池Ｂ４の＋端子とリチウム二次電池Ｂ５の−端子との間の接続点とされている。このような接続点は、組電池１を構成するいずれか２個のリチウム二次電池の間とすることができるが、特に上位側のリチウム二次電池の電圧検出精度を高めるためには、組電池１を構成するリチウム二次電池Ｂの個数ｎに応じて、個数ｎが偶数の場合には、ｎ／２番目のリチウム二次電池とｎ／２＋１番目のリチウム二次電池との間、個数ｎが奇数の場合には、（ｎ−１）／２番目のリチウム二次電池と（ｎ＋１）／２番目のリチウム二次電池の間とすることが好ましい。本実施形態では、リチウム二次電池の個数ｎが８で偶数であるので、８／２番面（＝４番目）のリチウム二次電池Ｂ４と８／２＋１番目（＝５番目）のリチウム二次電池Ｂ５との間が中点として求められる。
【００１５】
また、制御回路６は、正電源端子（ＶＣＣ）を最上位のリチウム二次電池Ｂ８の＋端子に接続し、負電源端子（ＶＥＥ）を最下位のリチウム二次電池Ｂ１の−端子に接続したＯＰアンプ６を備えている。ＯＰアンプ６の正相入力端子は上述した中点に接続されており、逆相入力端子は仮想グランドに接続されている。ＯＰアンプ６の出力は、ＮＰＮ形トランジスタ及びＰＮＰ形トランジスタのベースに接続されている。ＮＰＮ形トランジスタのコレクタは最上位のリチウム二次電池Ｂ８の＋端子に接続に接続されており、ＰＮＰ形トランジスタのコレクタは最下位のリチウム二次電池Ｂ１の−端子に接続されている。また、ＮＰＮ形トランジスタ及びＰＮＰ形トランジスタのエミッタは仮想グランドに接続されている。更に、この仮想グランドと最上位のリチウム二次電池Ｂ８の＋端子との間の電圧が電源部の電圧とされており、マイクロコンピュータ４を含む各部の作動電源が電源部から供給される構成とされている。
【００１６】
マルチプレクサ３はマイクロコンピュータ４のＡ／Ｄ入力ポートに接続されており、マイクロコンピュータ４の出力ポートはマルチプレクサ３に接続されている。従って、マイクロコンピュータ４はマルチプレクサ３の入力指定を出力ポートから指定し、マルチプレクサ３から入力された電圧を、仮想グランドの電圧を基準電圧としてＡ／Ｄ変換し、各リチウム二次電池の電池電圧をデジタル値として測定する。また、マイクロコンピュータ４は、電池電圧の測定データについてフォトカプラ５を介して上位システムと通信を行うために、シリアル出力ポートを有している。フォトカプラ５の発光ダイオードのアノードには抵抗の一端が接続されており、この抵抗の他端は仮想グランドに接続されている。発光ダイオードのカソードはＮＰＮ形トランジスタのコレクタに接続されており、ＮＰＮ形トランジスタのエミッタは最下位のリチウム二次電池Ｂ１の−端子に接続されている。また、マイクロコンピュータ４のシリアル出力ポートにはＰＮＰ形トランジスタのベースが接続されており、ＰＮＰ形トランジスタのエミッタは電源部に、コレクタは抵抗を介してＮＰＮ形トランジスタのベースに接続されている。
【００１７】
従って、本実施形態の制御回路が図３に示した従来の制御回路と大きく異なっているのは、（１）最上位のリチウム二次電池Ｂ８の＋端子と最下位のリチウム二次電池Ｂ１の−端子との間の電圧を作動電源とするＯＰアンプ６の正相入力端子がリチウム二次電池Ｂ４、Ｂ５間に接続されている点、（２）ＯＰアンプ６の逆相入力端子が仮想グランドとして差動増幅器２やマイクロコンピュータ４に接続されている点、及び（３）電池電圧の測定データを信号伝送するためのフォトカプラ５をこの仮想グランドと最下位のリチウム二次電池Ｂ１の−端子に接続されている点である。
【００１８】
上記実施形態の制御回路の各差動増幅器２の抵抗７１、７２、７３、７４に０．１％精度の抵抗を使用して多数個の実施例の制御回路を作製した。また、実施例の制御回路の効果を確認するために、図３に示した従来の制御回路の各差動増幅器２の抵抗７１、７２、７３、７４に、実施例と同様に、０．１％精度の抵抗を使用して多数個の比較例の制御回路を作製した。
【００１９】
実施例及び比較例の各制御回路について、２５°Ｃの常温下で電圧検出誤差を測定した。図２に両者の電圧誤差特性を示す。この電圧誤差特性は、誤差の３σの範囲を示したものである。図２に示すように、比較例の制御回路では電圧検出誤差が４０ｍＶであったのに対し、実施例の制御回路では３０ｍＶであった。従って、リチウム二次電池の電圧検出精度が向上したことが確認できた。
【００２０】
また、実施例及び比較例の各制御回路について、消費電流の平均値を求めた。なお、上述した３σの範囲外のものは、実施例及び比較例の制御回路共に作製不良として平均の母数及び対象から除外した。消費電流測定の結果、比較例の制御回路の平均値は５４ｍＡであったのに対し、実施例の制御回路の平均値は４３ｍＡであり、従来の制御回路に比較して消費電流が２０％低減したことが確認できた。
【００２１】
このように、リチウム二次電池の電圧検出精度が向上したのは、組電池１の中点と同電位の仮想グランドを基準に各リチウム二次電池の電池電圧を測定したためであり、中点を基準に電池電圧を測定することで、上位側に行くに従って誤差が累積される従来の制御回路と比べ、理論的にも各リチウム二次電池の電圧検出精度の向上が図られることが分かる。また、消費電流が低減したのは、上述したように従来例と異なる構成を採ることで、消費電流をフォトカプラ５の駆動電流と測定回路電流（ＯＰアンプ、トランジスタを流れる電流の総和）との大きい方の電流値とすることで両者の累積消費電流を避けるように構成したためである。
【００２２】
【発明の効果】
以上説明したように、本発明によれば、セル電圧変換回路の作動電源を組電池を構成するリチウム二次電池の最上位＋端子と最下位−端子とし、測定回路の作動電源を最上位＋端子と仮想グランドとの間から供給し、フォトカプラの主駆動電源を仮想グランドと最下位−端子との間から供給するので、フォトカプラを仮想グランドと最下位−端子の間で駆動することでフォトカプラと測定回路とは直列接続され、消費電流を（フォトカプラ駆動電流＋測定回路電流）からフォトカプラ駆動電流と測定回路電流のいずれか大きい方の電流値まで低減させることができる、という効果を得ることができる。
【図面の簡単な説明】
【図１】本発明が適用可能な実施の形態の制御回路のブロック図である。
【図２】実施例の制御回路のリチウム二次電池の電圧検出誤差を示す特性線図である。
【図３】従来の制御回路の構成例を示すブロック図である。
【符号の説明】
１ 組電池
２ 差動増幅器（セル電圧変換回路の一部）
３ マルチプレクサ（セル電圧変換回路の一部）
４ マイクロコンピュータ（測定回路）
５ フォトカプラ
６ ＯＰアンプ（セル電圧変換回路の一部）
Ｂ１〜Ｂ８ リチウム二次電池[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control circuit, and more particularly to a control circuit for an assembled battery in which a plurality of lithium secondary batteries are connected in series.
[0002]
[Prior art]
Conventionally, in an assembled battery in which a plurality of single cells such as lithium secondary batteries are connected in series, for example, as disclosed in Japanese Patent Application Laid-Open No. 11-113182, the battery voltage of each single cell is differentially set. It was detected by the amplifier based on the lowest-order terminal. As described above, the reason for detecting the battery voltage of each unit cell is that the discharge characteristics of the assembled battery when the lithium secondary battery constituting the assembled battery is overcharged or overdischarged due to charging / discharging. This is because it causes a decrease in safety, a decrease in safety due to overcharge, a decrease in life characteristics due to overdischarge, and the like.
[0003]
FIG. 3 shows a configuration example of a conventional control circuit that performs such voltage monitoring. As shown in FIG. 3, the assembled battery 1 includes eight lithium secondary batteries B 1 to B 8 connected in series. The battery voltage of each lithium secondary battery is input to the multiplexer 3 through the differential amplifier 2, and the output of the multiplexer 3 is input to the A / D conversion of the
[0004]
[Problems to be solved by the invention]
However, in the above-described conventional control circuit, since the battery voltage of each lithium secondary battery is detected by the differential amplifier with reference to the lowest-order terminal, the effect of the resistance error of the differential amplifier increases as the input voltage increases. As a result, there is a problem that as the number of lithium secondary batteries in series increases, the detection error of the battery voltage of the upper lithium secondary battery increases. In the lithium secondary battery, the voltage detection error needs to have a high accuracy of about ± several tens of mV, and if a high-precision resistor is used as the resistor of the differential amplifier to ensure the accuracy, the cost becomes high.
[0005]
Further, when a photocoupler is used for communication of measurement data with a host system, the photocoupler cannot perform reliable signal transmission unless a certain amount of current is applied. In particular, in an assembled battery or a battery module composed of a plurality of assembled batteries mounted on an automobile that generates spark noise, it is necessary to flow a certain amount of current through the photocoupler, which increases current consumption as a whole control circuit. There is a tendency. In order to reduce current consumption, a semiconductor element such as a microcomputer can be changed to a low power consumption element, but there is a problem that the cost is increased.
[0006]
In view of the above problems, an object of the present invention is to provide a control circuit with improved voltage detection accuracy, low cost, and low current consumption.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a control circuit for an assembled battery in which a plurality of lithium secondary batteries are connected in series, and a positive phase input terminal is connected to an arbitrary connection point of the assembled battery via a resistor. A cell voltage conversion circuit having a differential amplifier that outputs a voltage at a positive terminal of each lithium secondary battery that constitutes the assembled battery, and the lithium based on the virtual ground. A measurement circuit for measuring the battery voltage of the secondary battery, and a photocoupler for signal transfer of the battery voltage of each lithium secondary battery measured by the measurement circuit , wherein the virtual ground is a midpoint of the assembled battery (When the number of lithium secondary batteries n constituting the assembled battery is an even number: between n / 2 and n / 2 + 1th lithium secondary battery, when an odd number: (n-1) / 2 and (n + 1) / 2 The second lithium secondary battery) The cell voltage conversion circuit uses the uppermost + terminal and the lowermost − terminal of the lithium secondary battery constituting the assembled battery as an operation power supply, and the operation power supply of the measurement circuit includes the uppermost + terminal and the virtual ground. The main driving power of the photocoupler is supplied from between the virtual ground and the least significant terminal .
[0008]
This onset Ming, the cell voltage converting circuit is constituted with a differential amplifier, the cell voltage conversion circuit, a virtual positive phase input terminal is any connection point the same potential of the battery via a resistor The voltage of the + terminal of each lithium secondary battery constituting the assembled battery is output from the output terminal. Then, the measuring circuit, the battery voltage of each lithium secondary battery based on the virtual ground measurements, battery voltage of each lithium secondary battery measured by the measuring circuit by photocoupler Ru are signal transfer. In the present invention , since the battery voltage of each lithium secondary battery is measured with reference to a virtual ground having the same potential as an arbitrary connection point of the assembled battery, the input voltage of the differential amplifier of the cell voltage conversion circuit is the maximum voltage of the assembled battery. The voltage detection error is smaller than when the lower-terminal is used as a reference, and the voltage detection accuracy of each lithium secondary battery in the measurement circuit can be improved. In addition, since the virtual ground is the middle point of the battery pack, assuming that the common-mode input voltage rejection ratio of each differential amplifier is the same, the voltage detection error is half that of the battery pack with the lowest-terminal as the reference. Thus, the voltage detection accuracy can be further improved, and the voltage detection accuracy can be improved, so that the accuracy of the resistor used in the differential amplifier can be kept below a certain level, thereby reducing the cost of the control circuit. it can. Furthermore, the operating power of the cell voltage conversion circuit is the highest + terminal and the lowest-terminal of the lithium secondary battery constituting the assembled battery, and the operating power of the measurement circuit is supplied from between the highest + terminal and the virtual ground. Since the photocoupler's main drive power is supplied between the virtual ground and the lowest-terminal, the photocoupler and the measurement circuit are connected in series by driving the photocoupler between the virtual ground and the lowest-terminal. The current consumption can be reduced from (photocoupler drive current + measurement circuit current) to a current value that is larger of the photocoupler drive current and the measurement circuit current.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a control circuit to which the present invention can be applied will be described with reference to the drawings.
[0011]
As shown in FIG. 1, the control circuit of this embodiment is a voltage detection circuit of each lithium battery B of the assembled battery 1 in which eight lithium secondary batteries B 1 to B 8 are connected in series. This control circuit includes differential amplifiers 2 corresponding to the number of lithium batteries B. The differential amplifier 2 is composed of an OP amplifier and four resistors. The inverting input terminal of the OP amplifier is connected to one end of a resistor 71 and 72, the other end of the resistor 71 is connected to the positive terminal of the lithium secondary battery B 8. Inverting input terminal of the OP amplifier is connected to one end of the resistor 72 and 74, the other end of the resistor 72 of the lithium secondary battery B 8 - terminal and one lower the positive-phase input terminal of the differential amplifier They are connected via a resistor 71 of a differential amplifier.
[0012]
The other end of the resistor 73 is connected to a virtual ground. The other end of the resistor 74 is connected to the output terminal of the OP amplifier, and the output terminal of the OP amplifier is connected to the multiplexer 3. The positive power supply terminal (V CC) of the differential amplifier 2 is connected to the positive terminal of the lithium secondary battery B 8 uppermost, negative power supply terminal (V EE) is a lithium secondary battery of the lowest B 1 Connected to the negative terminal.
[0013]
Differential amplifier 2 of the lower is the connection with the same configuration as the differential amplifier 2 connected to a lithium secondary battery B 8 topmost have been made, are connected to a lithium secondary battery B 1 least significant differential amplifier 2 to the other end of the resistor 72 is the least significant of the lithium secondary battery B 1 of - is different in that it is connected to the terminal.
[0014]
Midpoint of the assembled battery 1 is a lithium secondary battery B 4 + terminal and the lithium secondary battery B 5 - there is a connection point between the terminals. Such a connection point can be between any two lithium secondary batteries constituting the assembled battery 1, but in order to increase the voltage detection accuracy of the upper lithium secondary battery, in particular, When the number n is an even number according to the number n of the lithium secondary batteries B constituting the battery 1, the number is between the n / 2th lithium secondary battery and the n / 2 + 1th lithium secondary battery. When n is an odd number, it is preferably between (n−1) / 2 th lithium secondary battery and (n + 1) / 2 th lithium secondary battery. In the present embodiment, since the number n of the lithium secondary battery is an even number at 8, the lithium secondary of 8/2 No. plane (= 4th) Lithium secondary battery B 4 and 8/2 + 1-th (= 5 th) between the next battery B 5 is determined as the midpoint.
[0015]
In addition, the control circuit 6 connects the positive power supply terminal (V CC ) to the + terminal of the uppermost lithium secondary battery B 8 and the negative power supply terminal (V EE ) to the − of the lowermost lithium secondary battery B 1 . An OP amplifier 6 connected to the terminal is provided. The positive phase input terminal of the OP amplifier 6 is connected to the above-described midpoint, and the negative phase input terminal is connected to a virtual ground. The output of the OP amplifier 6 is connected to the bases of the NPN transistor and the PNP transistor. Is connected to the terminal - the collector of the NPN type transistor is connected to the connection to the positive terminal of the lithium secondary battery B 8 uppermost, the collector of the PNP transistor is the lowest lithium secondary battery B 1 in. The emitters of the NPN transistor and the PNP transistor are connected to a virtual ground. In addition, the voltage between the virtual ground and the uppermost of the lithium secondary battery B 8 + terminal is the voltage of the power supply unit, configured to operate the power supply of each unit including a
[0016]
The multiplexer 3 is connected to the A / D input port of the
[0017]
Accordingly, the control circuit of the present embodiment is greatly different from the conventional control circuit shown in FIG. 3, (1) the top-level of a lithium secondary battery B 8 + terminal and the lowest of the lithium secondary battery B The point that the positive phase input terminal of the OP amplifier 6 that uses the voltage between the negative terminal of 1 as the operating power supply is connected between the lithium secondary batteries B 4 and B 5 , (2) the negative phase input of the OP amplifier 6 The terminal is connected to the differential amplifier 2 or the
[0018]
A large number of control circuits of Examples were manufactured by using resistances of 0.1% accuracy for the resistors 71, 72, 73, 74 of each differential amplifier 2 of the control circuit of the above embodiment. In order to confirm the effect of the control circuit of the embodiment, the resistance 71, 72, 73, 74 of each differential amplifier 2 of the conventional control circuit shown in FIG. A number of comparative control circuits were fabricated using% precision resistors.
[0019]
About each control circuit of an Example and a comparative example, the voltage detection error was measured under normal temperature of 25 degreeC. FIG. 2 shows both voltage error characteristics. This voltage error characteristic shows a 3σ range of error. As shown in FIG. 2, in the control circuit of the comparative example, the voltage detection error was 40 mV, whereas in the control circuit of the example, it was 30 mV. Therefore, it was confirmed that the voltage detection accuracy of the lithium secondary battery was improved.
[0020]
Moreover, the average value of the consumption current was calculated | required about each control circuit of an Example and a comparative example. In addition, the thing outside the range of 3σ mentioned above was excluded from the average parameter and the object as the production failure in the control circuits of the example and the comparative example. As a result of measuring current consumption, the average value of the control circuit of the comparative example was 54 mA, whereas the average value of the control circuit of the example was 43 mA, and the current consumption was reduced by 20% compared to the conventional control circuit. I was able to confirm.
[0021]
Thus, the voltage detection accuracy of the lithium secondary battery was improved because the battery voltage of each lithium secondary battery was measured with reference to a virtual ground having the same potential as the middle point of the assembled battery 1. It can be seen that measuring the battery voltage as a reference can theoretically improve the voltage detection accuracy of each lithium secondary battery as compared with the conventional control circuit in which errors are accumulated as going up. In addition, the consumption current is reduced by adopting a configuration different from the conventional example as described above, so that the consumption current is calculated by combining the driving current of the photocoupler 5 and the measurement circuit current (the sum of the current flowing through the OP amplifier and the transistor). This is because the larger current value is adopted so as to avoid the accumulated current consumption of both.
[0022]
【The invention's effect】
As described above, according to the present invention, the operating power source of the cell voltage conversion circuit is the uppermost + terminal and the lowermost − terminal of the lithium secondary battery constituting the assembled battery, and the operating power source of the measurement circuit is the uppermost + Since the main drive power of the photocoupler is supplied from between the virtual ground and the lowest-order terminal, the photocoupler is driven between the virtual ground and the lowest-order terminal. Photocoupler and measurement circuit are connected in series, and the current consumption can be reduced from (photocoupler drive current + measurement circuit current) to the current value of the photocoupler drive current or measurement circuit current, whichever is greater Can be obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram of a control circuit according to an embodiment to which the present invention is applicable.
FIG. 2 is a characteristic diagram showing a voltage detection error of a lithium secondary battery in the control circuit of the example.
FIG. 3 is a block diagram illustrating a configuration example of a conventional control circuit.
[Explanation of symbols]
1 battery pack 2 differential amplifier (part of cell voltage conversion circuit)
3 Multiplexer (part of cell voltage conversion circuit)
4 Microcomputer (measurement circuit)
5 Photocoupler 6 OP amplifier (part of cell voltage conversion circuit)
B1-B8 lithium secondary battery
Claims (1)
正相入力端子が抵抗を介して前記組電池の任意の接続点と同電位となる仮想グランドに接続され、前記組電池を構成する各リチウム二次電池の＋端子の電圧を出力する差動増幅器を有するセル電圧変換回路と、
前記仮想グランドを基準に前記各リチウム二次電池の電池電圧を測定する測定回路と、
前記測定回路で測定した各リチウム二次電池の電池電圧を信号転送するためのフォトカプラと、
を備え、前記仮想グランドは前記組電池の中点（前記組電池を構成するリチウム二次電池数ｎが偶数の場合：ｎ／２とｎ／２＋１番目のリチウム二次電池間、奇数の場合：（ｎ−１）／２と（ｎ＋１）／２番目のリチウム二次電池間）であり、前記セル電圧変換回路は前記組電池を構成するリチウム二次電池の最上位＋端子と最下位−端子とを作動電源とし、前記測定回路の作動電源は前記最上位＋端子と前記仮想グランドとの間から供給され、前記フォトカプラの主駆動電源が前記仮想グランドと前記最下位−端子との間から供給されることを特徴とする制御回路。A control circuit for an assembled battery in which a plurality of lithium secondary batteries are connected in series,
A differential amplifier whose positive phase input terminal is connected to a virtual ground having the same potential as an arbitrary connection point of the assembled battery via a resistor, and outputs a voltage at the + terminal of each lithium secondary battery constituting the assembled battery A cell voltage conversion circuit comprising:
A measurement circuit for measuring a battery voltage of each lithium secondary battery with reference to the virtual ground;
A photocoupler for signal transfer of the battery voltage of each lithium secondary battery measured by the measurement circuit;
And the virtual ground is a midpoint of the assembled battery (when the number n of lithium secondary batteries constituting the assembled battery is an even number: between n / 2 and n / 2 + 1th lithium secondary battery, an odd number: (N-1) / 2 and (n + 1) / 2th lithium secondary battery), and the cell voltage conversion circuit is the most significant + terminal and the least significant-terminal of the lithium secondary battery constituting the assembled battery. And the operating power of the measurement circuit is supplied from between the uppermost + terminal and the virtual ground, and the main driving power of the photocoupler is from between the virtual ground and the lowermost-terminal. A control circuit which is supplied .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001250996A JP4026337B2 (en) | 2001-08-22 | 2001-08-22 | Control circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001250996A JP4026337B2 (en) | 2001-08-22 | 2001-08-22 | Control circuit |
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| Publication Number | Publication Date |
|---|---|
| JP2003070171A JP2003070171A (en) | 2003-03-07 |
| JP4026337B2 true JP4026337B2 (en) | 2007-12-26 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP4589888B2 (en) | 2006-03-23 | 2010-12-01 | 株式会社ケーヒン | Battery voltage measurement circuit and battery ECU |
| JP4702331B2 (en) * | 2006-10-25 | 2011-06-15 | 株式会社デンソー | Semiconductor integrated circuit device |
| JP5685624B2 (en) * | 2008-07-01 | 2015-03-18 | 株式会社日立製作所 | Battery system |
| JP5486780B2 (en) | 2008-07-01 | 2014-05-07 | 株式会社日立製作所 | Battery system |
| WO2015060576A1 (en) | 2013-10-25 | 2015-04-30 | 주식회사 엘지화학 | Battery management system capable of transmitting secondary protection signal and diagnostic signal using few insulation elements |
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