JP2002164065A - Fuel cell and its operating method - Google Patents
Fuel cell and its operating methodInfo
- Publication number
- JP2002164065A JP2002164065A JP2000359995A JP2000359995A JP2002164065A JP 2002164065 A JP2002164065 A JP 2002164065A JP 2000359995 A JP2000359995 A JP 2000359995A JP 2000359995 A JP2000359995 A JP 2000359995A JP 2002164065 A JP2002164065 A JP 2002164065A
- Authority
- JP
- Japan
- Prior art keywords
- fuel cell
- voltage
- cell stack
- wet state
- fuel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
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Classifications
-
- 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
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
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- Fuel Cell (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、固体電解質型の燃
料電池及びその運転方法に係り、特に電極や電解質膜の
湿度を適切に制御することができる燃料電池及びその運
転方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolyte fuel cell and a method of operating the same, and more particularly to a fuel cell capable of appropriately controlling the humidity of electrodes and an electrolyte membrane and a method of operating the same.
【０００２】[0002]
【従来の技術】近年の環境問題、特に自動車の排気ガス
による大気汚染や二酸化炭素による地球温暖化の問題に
対して、クリーンな排気及び高いエネルギー効率を可能
とする電力源、あるいは動力源として、燃料電池技術が
注目されている。2. Description of the Related Art As a power source or a power source capable of achieving clean exhaust and high energy efficiency, in response to recent environmental problems, in particular, the problem of air pollution caused by automobile exhaust gas and global warming caused by carbon dioxide. Fuel cell technology is attracting attention.
【０００３】燃料電池の単セルは、イオン伝導体である
電解質膜の両側に触媒を含む電極を接合して構成され
る。そして２つの電極にそれぞれ燃料ガスと酸化ガス、
例えば水素を含むガスと空気とを供給する。水素が供給
されるアノード（燃料極）では、水素が水素イオンと電
子とに電離する。電子は外部回路を通って陽極に戻り、
水素イオンは電解質膜を通ってカソード（空気極）に達
する。空気中の酸素が供給されるカソードでは、水素イ
オンと酸素と電子とが反応して水が生成される。[0003] A single cell of a fuel cell is constituted by joining electrodes containing a catalyst to both sides of an electrolyte membrane which is an ion conductor. Then, fuel gas and oxidizing gas are respectively applied to the two electrodes,
For example, a gas containing hydrogen and air are supplied. At the anode (fuel electrode) to which hydrogen is supplied, hydrogen is ionized into hydrogen ions and electrons. The electrons return to the anode through an external circuit,
Hydrogen ions reach the cathode (air electrode) through the electrolyte membrane. At the cathode to which oxygen in the air is supplied, hydrogen ions, oxygen, and electrons react to generate water.
【０００４】燃料電池の単セルの理論的な起電力は、約
１．２Ｖと低いので、通常複数セルを積み重ねて直列接
続としたスタック構造が用いられる。燃料電池の中でも
特に高い出力密度を有する固体高分子電解質型燃料電池
が自動車等の移動体用動力源として注目されている。[0004] Since the theoretical electromotive force of a single cell of a fuel cell is as low as about 1.2 V, a stack structure in which a plurality of cells are stacked and connected in series is usually used. Among the fuel cells, a solid polymer electrolyte fuel cell having a particularly high output density has attracted attention as a power source for a mobile body such as an automobile.
【０００５】このような燃料電池の運転において重要な
点は、電極触媒及び固体高分子電解質膜の湿潤状態を適
正に保つことである。これらが乾燥気味であれば、イオ
ン伝導度が低下し、発電装置としての内部抵抗が増加す
る。水素と酸素との反応による生成水等により湿潤が過
ぎれば、ガスを取り込む有効電極面積が減少して出力電
流が減少する。An important point in the operation of such a fuel cell is to appropriately maintain the wet state of the electrode catalyst and the solid polymer electrolyte membrane. If these are slightly dry, the ionic conductivity decreases and the internal resistance of the power generation device increases. If the water is excessively wetted by the water produced by the reaction between hydrogen and oxygen, the area of the effective electrode for taking in the gas decreases, and the output current decreases.
【０００６】従来の燃料電池における電極及び固体高分
子電解質膜の湿潤状態を適正に制御する技術として、特
開平７−２２０４７号公報記載の技術が知られている。
この従来技術によれば、燃料電池内に安定した基準電位
を示す参照電極を設け、この参照電極に対するセルのア
ノード及びカソードの電位を測定し、この電位に基づい
て燃料ガスまたは酸化ガスの加湿量を調節していた。As a technique for appropriately controlling the wet state of the electrode and the solid polymer electrolyte membrane in a conventional fuel cell, a technique described in Japanese Patent Application Laid-Open No. 7-22047 is known.
According to this conventional technique, a reference electrode showing a stable reference potential is provided in a fuel cell, and the potentials of an anode and a cathode of the cell with respect to the reference electrode are measured. Based on this potential, the humidification amount of a fuel gas or an oxidizing gas is measured. Had been adjusted.
【０００７】[0007]
【発明が解決しようとする課題】しかしながら、上記従
来技術は、燃料電池内の参照電極に対するアノード及び
カソードの電位を測定するという構成になっていたた
め、参照電極を有していない燃料電池には適用ができな
いという問題点があった。However, the above-mentioned prior art is configured to measure the potentials of the anode and the cathode with respect to the reference electrode in the fuel cell, and is therefore applied to a fuel cell having no reference electrode. There was a problem that can not be.
【０００８】また、上記従来技術は、出力電流に対する
アノード及びカソード電位の変化により、水分の過剰あ
るいは膜の乾燥を判定するという構成になっていたた
め、ある程度以上の出力電流を引き出さないと、特異な
反応が見られず、湿潤状態の判定が困難であるという問
題点があった。In addition, the above-mentioned prior art has a configuration in which the excess of water or the drying of the film is determined based on the change in the anode and cathode potentials with respect to the output current. There was a problem that no reaction was observed and it was difficult to determine the wet state.
【０００９】さらに、上記従来技術は、アノード及びカ
ソード両極に電位変化の特異性が認められた時、水分の
過剰及び膜の乾燥の両方が原因となる可能性があるた
め、両者の区別に時間がかかる。具体的には一度乾燥状
態にし、その電位変化を測定した後に初めて、両者の区
別が判定できるため、早急な出力回復が困難であるとい
う問題点があった。Further, in the above prior art, when the specificity of the potential change is recognized in both the anode and the cathode, there is a possibility that both the excess of water and the drying of the membrane may be the cause. It takes. Specifically, there is a problem that it is difficult to quickly recover the output because the distinction between the two can be determined only after the device is once dried and its potential change is measured.
【００１０】以上の問題点に鑑み本発明の目的は、燃料
電池の各セルに参照電極を設けることなく、湿潤状態を
検出して運転を制御できる燃料電池及びその運転方法を
提供することである。[0010] In view of the above problems, an object of the present invention is to provide a fuel cell capable of detecting a wet state and controlling the operation without providing a reference electrode in each cell of the fuel cell, and a method of operating the fuel cell. .
【００１１】また本発明の目的は、特に燃料電池の出力
電流を引き出すことなく、湿潤状態の判定が容易に行え
る燃料電池及びその運転方法を提供することである。It is another object of the present invention to provide a fuel cell and a method of operating the fuel cell, which can easily determine the wet state without drawing the output current of the fuel cell.
【００１２】さらに本発明の目的は、適正な湿潤状態か
ら水分過剰または乾燥のいずれの方向に変移したかを容
易に判定することができる燃料電池及びその運転方法を
提供することである。It is a further object of the present invention to provide a fuel cell and a method of operating the fuel cell, which can easily determine whether the state has shifted from an appropriate wet state to an excessive moisture state or a dry state.
【００１３】[0013]
【課題を解決するための手段】請求項１記載の発明は、
上記課題を解決するため、燃料電池スタックを構成する
複数のセルから選ばれた少なくとも２つのセルの電圧を
検出する電圧検出手段と、少なくとも電圧検出手段によ
るセル電圧検出時に、燃料電池スタックのセル配列方向
に燃料ガス及び酸化ガスの相対湿度分布を形成する湿度
分布形成手段と、電圧検出手段が検出した各セル毎の電
圧分布を調べて、相対湿度が低いセルの電圧が相対湿度
が高いセルの電圧に比べて低い場合に、燃料電池の湿潤
が不十分と判定する湿潤状態判定手段と、を備えたこと
を要旨とする燃料電池である。According to the first aspect of the present invention,
In order to solve the above-mentioned problem, voltage detecting means for detecting a voltage of at least two cells selected from a plurality of cells constituting a fuel cell stack, and a cell arrangement of the fuel cell stack at least when a cell voltage is detected by the voltage detecting means. The humidity distribution forming means for forming the relative humidity distribution of the fuel gas and the oxidizing gas in the direction, and the voltage distribution of each cell detected by the voltage detecting means are checked, and the voltage of the cell having a lower relative humidity is higher than that of the cell having a higher relative humidity. And a wet state determining means for determining that the fuel cell is not sufficiently wet when the voltage is lower than the voltage.
【００１４】請求項２記載の発明は、上記課題を解決す
るため、請求項１記載の燃料電池において、前記湿度分
布形成手段は、燃料ガス及び酸化ガスの燃料電池スタッ
クへの流入方向と冷却水流入方向とを通常運転時には同
方向とする一方、前記湿潤状態判定手段による湿潤状態
判定のための前記電圧検出手段による電圧検出時には逆
方向に切り替えることで、燃料電池スタックのセル配列
方向に燃料ガス及び酸化ガスの相対湿度分布を形成する
冷却手段であることを要旨とする。According to a second aspect of the present invention, there is provided a fuel cell according to the first aspect, wherein the humidity distribution forming means includes a fuel gas and an oxidizing gas flowing into the fuel cell stack in a direction in which the cooling gas flows. The inflow direction is set to the same direction during the normal operation, while the flow direction is switched to the opposite direction when the voltage is detected by the voltage detection means for determining the wet state by the wet state determination means, so that the fuel gas flows in the cell arrangement direction of the fuel cell stack. And a cooling means for forming a relative humidity distribution of the oxidizing gas.
【００１５】請求項３記載の発明は、上記課題を解決す
るため、請求項１記載の燃料電池において、前記湿度分
布形成手段は、燃料ガス及び酸化ガスの燃料電池スタッ
クへの流入方向と冷却水流入方向とを常に逆方向とし、
燃料電池スタックのセル配列方向に燃料ガス及び酸化ガ
スの相対湿度分布を形成する冷却手段であることを要旨
とする。According to a third aspect of the present invention, in the fuel cell according to the first aspect of the present invention, the humidity distribution forming means includes a fuel gas and an oxidizing gas flowing into the fuel cell stack and a cooling water flowing direction. The direction of inflow is always reverse,
The gist is a cooling means for forming a relative humidity distribution of the fuel gas and the oxidizing gas in the cell arrangement direction of the fuel cell stack.
【００１６】請求項４記載の発明は、上記課題を解決す
るため、燃料電池スタック運転中の電圧と電流とを測定
する電圧電流測定手段と、この電圧電流測定手段が測定
した電圧電流特性に基づいて、燃料電池スタックの内部
抵抗値を推定する内部抵抗推定手段と、この推定された
内部抵抗値と予め記憶した標準値との比較に基づいて、
燃料電池の湿潤状態を判定する湿潤状態判定手段と、を
備えたことを要旨とする燃料電池である。According to a fourth aspect of the present invention, there is provided a voltage / current measuring means for measuring voltage and current during operation of a fuel cell stack, and a voltage / current characteristic measured by the voltage / current measuring means. An internal resistance estimating means for estimating the internal resistance value of the fuel cell stack, and comparing the estimated internal resistance value with a previously stored standard value,
And a wet state determining means for determining a wet state of the fuel cell.
【００１７】請求項５記載の発明は、上記課題を解決す
るため、請求項４記載の燃料電池において、燃料電池の
温度を測定する温度測定手段と、測定された温度に基づ
いて前記標準値を変更する標準値変更手段と、を更に備
えたことを要旨とする。According to a fifth aspect of the present invention, there is provided a fuel cell as set forth in the fourth aspect, wherein a temperature measuring means for measuring a temperature of the fuel cell, and the standard value is determined based on the measured temperature. And a standard value changing means for changing the standard value.
【００１８】請求項６記載の発明は、上記課題を解決す
るため、燃料電池スタックへ流入する燃料ガス及び酸化
ガスの水分量を検出する流入水分量検出手段と、燃料電
池スタックから流出する燃料ガス及び酸化ガスの水分量
を検出する流出水分量検出手段と、燃料電池スタック内
部で生成された水分量を推定する生成水分量推定手段
と、前記生成された水分量及び流入水分量及び流出水分
量に基づいて燃料電池の湿潤状態を判定する湿潤状態判
定手段と、を備えたことを要旨とする燃料電池である。According to a sixth aspect of the present invention, there is provided a fuel gas stack comprising: a fuel gas and an oxidizing gas flowing into the fuel cell stack; and a fuel gas flowing out of the fuel cell stack. Outflow water amount detection means for detecting the water amount of the oxidizing gas, generated water amount estimation means for estimating the water amount generated in the fuel cell stack, the generated water amount, the inflow water amount and the outflow water amount And a wet state determination means for determining a wet state of the fuel cell based on the fuel cell.
【００１９】請求項７記載の発明は、上記課題を解決す
るため、請求項１ないし請求項６のいずれか１項記載の
燃料電池において、前記湿潤状態判定手段が湿潤が不十
分と判定したとき、燃料電池の出力を制限する出力制限
手段を更に備えたことを要旨とする。According to a seventh aspect of the present invention, there is provided a fuel cell as set forth in any one of the first to sixth aspects, wherein the wet state determination means determines that the wetness is insufficient. The gist of the present invention is to further include output limiting means for limiting the output of the fuel cell.
【００２０】請求項８記載の発明は、上記課題を解決す
るため、燃料電池スタックのセル配列方向に燃料ガス及
び酸化ガスの相対湿度分布を形成する湿度分布形成過程
と、燃料電池スタックを構成する複数のセルから選ばれ
た少なくとも２つのセルの電圧を検出する電圧検出過程
と、各セル毎の電圧分布を調べて、相対湿度が低いセル
の電圧が相対湿度が高いセルの電圧に比べて低い場合
に、燃料電池の湿潤が不十分と判定する湿潤状態判定過
程と、この湿潤状態判定過程で湿潤が不十分と判定した
とき、燃料電池の出力を制限する出力制限過程と、を備
えたことを要旨とする燃料電池の運転方法である。According to an eighth aspect of the present invention, there is provided a fuel cell stack comprising: a humidity distribution forming step of forming a relative humidity distribution of a fuel gas and an oxidizing gas in a cell arrangement direction of a fuel cell stack; A voltage detecting step of detecting voltages of at least two cells selected from a plurality of cells, and a voltage distribution of each cell are examined, and a voltage of a cell having a low relative humidity is lower than a voltage of a cell having a high relative humidity. In this case, there is provided a wet state determining step of determining that the fuel cell is not sufficiently wet, and an output limiting step of limiting the output of the fuel cell when the wet state is determined to be insufficient in the wet state determining step. This is a method for operating a fuel cell having the following features.
【００２１】請求項９記載の発明は、上記課題を解決す
るため、燃料電池スタック運転中の電圧と電流とを測定
する電圧電流測定過程と、この測定された電圧電流特性
に基づいて、燃料電池スタックの内部抵抗値を推定する
内部抵抗推定過程と、この推定された内部抵抗値と予め
記憶した標準値との比較に基づいて、燃料電池の湿潤状
態を判定する湿潤状態判定過程と、この湿潤状態判定過
程で湿潤が不十分と判定したとき、燃料電池の出力を制
限する出力制限過程と、を備えたことを要旨とする燃料
電池の運転方法である。According to a ninth aspect of the present invention, there is provided a voltage / current measuring step of measuring voltage and current during operation of a fuel cell stack, and a fuel cell based on the measured voltage / current characteristics. An internal resistance estimating step of estimating an internal resistance value of the stack, a wet state determining step of determining a wet state of the fuel cell based on a comparison between the estimated internal resistance value and a standard value stored in advance, An output limiting step of limiting the output of the fuel cell when it is determined that the wetness is insufficient in the state determining step.
【００２２】[0022]
【発明の効果】請求項１記載の発明によれば、燃料電池
スタックを構成する複数のセルから選ばれた少なくとも
２つのセルの電圧を検出する電圧検出手段と、少なくと
も前記電圧検出手段によるセル電圧検出時に、燃料電池
スタックのセル配列方向に燃料ガス及び酸化ガスの相対
湿度分布を形成する湿度分布形成手段と、前記電圧検出
手段が検出した各セル毎の電圧分布を調べて、相対湿度
が低いセルの電圧が相対湿度が高いセルの電圧に比べて
低い場合に、燃料電池の湿潤が不十分と判定する湿潤状
態判定手段と、を備えたので、相対湿度が高いセルの電
圧と相対湿度の低いセルの電圧の測定結果に基づいて燃
料電池の湿潤状態が水分過剰か水分不足かを正確に判定
することができるという効果を奏する。また湿潤状態の
判定が正確になるので、不要な水素パージを低減し、燃
料電池の燃費を向上するという効果を奏する。According to the first aspect of the present invention, voltage detecting means for detecting a voltage of at least two cells selected from a plurality of cells constituting a fuel cell stack, and a cell voltage by at least the voltage detecting means At the time of detection, a humidity distribution forming unit that forms a relative humidity distribution of the fuel gas and the oxidizing gas in the cell array direction of the fuel cell stack, and a voltage distribution of each cell detected by the voltage detecting unit are checked, and the relative humidity is low. When the voltage of the cell is lower than the voltage of the cell having a higher relative humidity, the wet state determination means for determining that the fuel cell is not sufficiently wet is provided. It is possible to accurately determine whether the wet state of the fuel cell is excessive or insufficient based on the measurement result of the low cell voltage. In addition, since the determination of the wet state becomes accurate, there is an effect that unnecessary hydrogen purge is reduced and fuel efficiency of the fuel cell is improved.
【００２３】請求項２記載の発明によれば、請求項１記
載の発明の効果に加えて、前記湿度分布形成手段は、燃
料ガス及び酸化ガスの燃料電池スタックへの流入方向と
冷却水流入方向とを通常運転時には同方向とする一方、
前記湿潤状態判定手段による湿潤状態判定のための前記
電圧検出手段による電圧検出時には逆方向に切り替える
ことで、燃料電池スタックのセル配列方向に燃料ガス及
び酸化ガスの相対湿度分布を形成する冷却手段であると
したので、通常運転時に好適な相対湿度分布と湿潤状態
判定時に好適な相対湿度分布との双方の相対湿度分布を
形成し、通常運転時の発電効率を低下させることなく、
正確な湿潤状態の判定を行うことができるという効果を
奏する。According to the second aspect of the present invention, in addition to the effect of the first aspect, the humidity distribution forming means includes a flow direction of the fuel gas and the oxidizing gas into the fuel cell stack and a flow direction of the cooling water. And during normal operation the same direction,
When the voltage is detected by the voltage detecting means for determining the wet state by the wet state determining means, the voltage is switched in the reverse direction to form a relative humidity distribution of the fuel gas and the oxidizing gas in the cell array direction of the fuel cell stack. Since there is, forming a relative humidity distribution of both a suitable relative humidity distribution during normal operation and a suitable relative humidity distribution when determining the wet state, without lowering the power generation efficiency during normal operation,
There is an effect that an accurate determination of the wet state can be performed.
【００２４】請求項３記載の発明によれば、請求項１記
載の発明の効果に加えて、前記湿度分布形成手段は、燃
料ガス及び酸化ガスの燃料電池スタックへの流入方向と
冷却水流入方向とを常に逆方向とし、燃料電池スタック
のセル配列方向に燃料ガス及び酸化ガスの相対湿度分布
を形成する冷却手段であるとしたので、冷却水流入方向
切り替え機能を設けて冷却手段を複雑にすることなく、
正確な湿潤状態の判定を行うことができるという効果を
奏する。According to the third aspect of the present invention, in addition to the effect of the first aspect, the humidity distribution forming means includes a direction in which the fuel gas and the oxidizing gas flow into the fuel cell stack and a direction in which the cooling water flows. And the cooling means for forming the relative humidity distribution of the fuel gas and the oxidizing gas in the cell array direction of the fuel cell stack, so that a cooling water inflow direction switching function is provided to complicate the cooling means. Without
There is an effect that an accurate determination of the wet state can be performed.
【００２５】請求項４記載の発明によれば、燃料電池ス
タック運転中の電圧と電流とを測定する電圧電流測定手
段と、該電圧電流測定手段が測定した電圧電流特性に基
づいて、燃料電池スタックの内部抵抗値を推定する内部
抵抗推定手段と、前記推定された内部抵抗値と予め記憶
した標準値との比較に基づいて、燃料電池の湿潤状態を
判定する湿潤状態判定手段と、を備えたので、燃料電池
スタックに相対湿度分布を形成することなく、湿潤状態
を判定することができるという効果を奏する。According to the fourth aspect of the present invention, the voltage / current measuring means for measuring the voltage and the current during the operation of the fuel cell stack, and the fuel cell stack based on the voltage / current characteristics measured by the voltage / current measuring means Internal resistance estimating means for estimating the internal resistance value of the fuel cell, and wet state determining means for determining a wet state of the fuel cell based on a comparison between the estimated internal resistance value and a previously stored standard value. Therefore, it is possible to determine the wet state without forming a relative humidity distribution in the fuel cell stack.
【００２６】請求項５記載の発明によれば、請求項４記
載の発明の効果に加えて、燃料電池の温度を測定する温
度測定手段と、測定された温度に基づいて前記標準値を
変更する標準値変更手段と、を更に備えたので、燃料電
池の運転温度に変化があっても正確な湿潤状態判定を行
うことができるという効果を奏する。According to the fifth aspect of the present invention, in addition to the effect of the fourth aspect, in addition to the temperature measuring means for measuring the temperature of the fuel cell, the standard value is changed based on the measured temperature. Since the standard value changing means is further provided, there is an effect that accurate determination of the wet state can be performed even if the operating temperature of the fuel cell changes.
【００２７】請求項６記載の発明によれば、燃料電池ス
タックへ流入する燃料ガス及び酸化ガスの水分量を検出
する流入水分量検出手段と、燃料電池スタックから流出
する燃料ガス及び酸化ガスの水分量を検出する流出水分
量検出手段と、燃料電池スタック内部で生成された水分
量を推定する生成水分量推定手段と、前記生成された水
分量及び流入水分量及び流出水分量に基づいて燃料電池
の湿潤状態を判定する湿潤状態判定手段と、を備えたこ
とにより、燃料電池スタック内部の水分量の変化履歴を
正確に追跡し、燃料電池の湿潤状態を正確に判定するこ
とができるという効果を奏する。According to the sixth aspect of the present invention, the inflow moisture detecting means for detecting the moisture content of the fuel gas and the oxidizing gas flowing into the fuel cell stack, and the moisture of the fuel gas and the oxidizing gas flowing out of the fuel cell stack. Means for detecting the amount of effluent water to detect the amount of water, means for estimating the amount of water generated inside the fuel cell stack, and means for estimating the amount of water generated inside the fuel cell stack; And a wet state determining means for determining the wet state of the fuel cell stack. Thus, it is possible to accurately track the change history of the water content inside the fuel cell stack and accurately determine the wet state of the fuel cell. Play.
【００２８】請求項７記載の発明によれば、請求項１な
いし請求項６記載の発明の効果に加えて、前記湿潤状態
判定手段が湿潤が不十分と判定したとき、燃料電池の出
力を制限する出力制限手段を更に備えたので、燃料電池
の乾燥状態からの回復と運転継続とを両立させることが
できるという効果を奏する。According to the seventh aspect of the invention, in addition to the effects of the first to sixth aspects, the output of the fuel cell is limited when the wet state determination means determines that the wetness is insufficient. Since the output limiter is further provided, it is possible to achieve both the recovery from the dry state of the fuel cell and the continuation of the operation.
【００２９】請求項８記載の発明によれば、燃料電池ス
タックのセル配列方向に燃料ガス及び酸化ガスの相対湿
度分布を形成する湿度分布形成過程と、燃料電池スタッ
クを構成する複数のセルから選ばれた少なくとも２つの
セルの電圧を検出する電圧検出過程と、各セル毎の電圧
分布を調べて、相対湿度が低いセルの電圧が相対湿度が
高いセルの電圧に比べて低い場合に、燃料電池の湿潤が
不十分と判定する湿潤状態判定過程と、前記湿潤状態判
定過程で湿潤が不十分と判定したとき、燃料電池の出力
を制限する出力制限過程と、を備えたので、相対湿度が
高いセルの電圧と相対湿度の低いセルの電圧の測定結果
に基づいて燃料電池の湿潤状態が水分過剰か水分不足か
を正確に判定することができるという効果を奏する。ま
た湿潤状態の判定が正確になるので、不要な水素パージ
を低減し、燃料電池の燃費を向上するという効果を奏す
る。According to the eighth aspect of the present invention, the humidity distribution forming step of forming the relative humidity distribution of the fuel gas and the oxidizing gas in the cell arrangement direction of the fuel cell stack, and a plurality of cells constituting the fuel cell stack are selected. A voltage detection process for detecting the voltage of at least two of the cells, and a voltage distribution of each cell. If the voltage of the cell having a lower relative humidity is lower than the voltage of the cell having a higher relative humidity, the fuel cell A wet state determination step for determining that the wetness is insufficient, and an output limiting step for limiting the output of the fuel cell when the wet state is determined to be insufficient in the wet state determination step, so that the relative humidity is high. It is possible to accurately determine whether the wet state of the fuel cell is excessive or insufficient based on the measurement results of the cell voltage and the cell voltage having a low relative humidity. In addition, since the determination of the wet state becomes accurate, there is an effect that unnecessary hydrogen purge is reduced and fuel efficiency of the fuel cell is improved.
【００３０】請求項９記載の発明によれば、燃料電池ス
タック運転中の電圧と電流とを測定する電圧電流測定過
程と、前記測定された電圧電流特性に基づいて、燃料電
池スタックの内部抵抗値を推定する内部抵抗推定過程
と、前記推定された内部抵抗値と予め記憶した標準値と
の比較に基づいて、燃料電池の湿潤状態を判定する湿潤
状態判定過程と、前記湿潤状態判定過程で湿潤が不十分
と判定したとき、燃料電池の出力を制限する出力制限過
程と、を備えたので、燃料電池スタックに相対湿度分布
を形成することなく、湿潤状態を判定することができる
という効果を奏する。また湿潤状態の判定が正確になる
ので、不要な水素パージを低減し、燃料電池の燃費を向
上するという効果を奏する。According to the ninth aspect of the present invention, the voltage / current measuring step of measuring the voltage and the current during the operation of the fuel cell stack, and the internal resistance value of the fuel cell stack based on the measured voltage / current characteristics An internal resistance estimating step of estimating the wet state of the fuel cell based on a comparison between the estimated internal resistance value and a standard value stored in advance. And an output limiting step of limiting the output of the fuel cell when it is determined that the fuel cell stack is insufficient, so that the wet state can be determined without forming a relative humidity distribution in the fuel cell stack. . In addition, since the determination of the wet state becomes accurate, there is an effect that unnecessary hydrogen purge is reduced and fuel efficiency of the fuel cell is improved.
【００３１】[0031]
【発明の実施の形態】次に、図面を参照して、本発明の
実施の形態を詳細に説明する。 〔第１の実施形態〕図１は、本発明に係る燃料電池の第
１の実施形態の構成を説明する全体構成図である。図１
において、燃料電池は、燃料ガスとしての水素を含むガ
ス（以下、水素含有ガス）を所望の圧力・流量で供給す
る水素供給部１と、酸化ガスとしての空気を所望の圧力
・流量で供給する空気供給部２と、図示しない純水供給
器から供給される純水で水素含有ガスと空気とをそれぞ
れ加湿する加湿器３と、加湿器３で加湿された水素含有
ガス及び空気が供給される燃料電池スタック４と、使用
されなかった水素を再循環させる燃料循環用ポンプ５
と、水素含有ガスの逆流を防止する逆止弁６と、燃料電
池スタック４を冷却するとともに、湿潤状態判定のため
の電圧測定時には燃料電池スタック４への冷却水の流入
方向を燃料電池スタック４へのガス流入方向とは逆方向
とすることができる冷却系１２と、これらの装置を制御
する制御装置１１とを備えている。Next, an embodiment of the present invention will be described in detail with reference to the drawings. [First Embodiment] FIG. 1 is an overall configuration diagram illustrating the configuration of a first embodiment of a fuel cell according to the present invention. FIG.
, A fuel cell supplies a hydrogen-containing gas (hereinafter referred to as a hydrogen-containing gas) as a fuel gas at a desired pressure and flow rate, and supplies air as an oxidizing gas at a desired pressure and flow rate. An air supply unit 2, a humidifier 3 for humidifying the hydrogen-containing gas and the air with pure water supplied from a pure water supply unit (not shown), and a hydrogen-containing gas and air humidified by the humidifier 3 are supplied. Fuel cell stack 4 and fuel circulation pump 5 for recycling unused hydrogen
A check valve 6 for preventing a backflow of the hydrogen-containing gas; a fuel cell stack 4 for cooling the fuel cell stack 4 and a flow direction of the cooling water into the fuel cell stack 4 when measuring a voltage for judging a wet state. A cooling system 12 which can be in a direction opposite to the gas inflow direction to the air, and a control device 11 for controlling these devices are provided.
【００３２】燃料電池スタック４には、スタックを構成
する複数のセルから選ばれた２つ以上のセル、好ましく
は全てのセルのそれぞれの電圧を検出する電圧検出手段
である図示しない電圧検出器が設けられ、この電圧検出
器の検出信号は、制御装置１１へ伝えられるようになっ
ている。The fuel cell stack 4 includes a voltage detector (not shown) which is a voltage detector for detecting the voltage of each of two or more cells selected from a plurality of cells constituting the stack, preferably all the cells. The detection signal of the voltage detector is provided to the control device 11.
【００３３】冷却系１２は、燃料電池スタック４の内部
に設けられた図示しない冷却水流路と、冷却水を循環さ
せる冷却水ポンプ７と、冷却水の熱を外部へ放熱するラ
ジエータまたはラジエータとラジエータファンの組８
と、燃料電池スタック４に流れる冷却水の方向を反転さ
せる４方弁９と、冷却水温度を測定する温度計１０と、
これらを接続する管路と、これらの内部に充填された冷
却水とを備えている。The cooling system 12 includes a cooling water passage (not shown) provided inside the fuel cell stack 4, a cooling water pump 7 for circulating cooling water, a radiator or a radiator for radiating heat of the cooling water to the outside, and a radiator. Fan Set 8
A four-way valve 9 for reversing the direction of the cooling water flowing through the fuel cell stack 4, a thermometer 10 for measuring the temperature of the cooling water,
A pipeline connecting them and a cooling water filled therein are provided.
【００３４】そして、冷却系１２は、電圧検出手段によ
るセル電圧検出時に、燃料電池スタックのセル配列方向
に燃料ガス及び酸化ガスの相対湿度分布を形成する湿度
分布形成手段を構成している。The cooling system 12 constitutes a humidity distribution forming means for forming a relative humidity distribution of the fuel gas and the oxidizing gas in the cell arrangement direction when the cell voltage is detected by the voltage detecting means.
【００３５】また制御装置１１は、水素供給部１、空気
供給部２及び温度計１０からの検出信号を受信する一
方、水素供給部１、空気供給部２、冷却水ポンプ７、４
方弁９を制御する制御信号を送出するようになってい
る。The control device 11 receives detection signals from the hydrogen supply unit 1, the air supply unit 2, and the thermometer 10, while the hydrogen supply unit 1, the air supply unit 2, the cooling water pumps 7, 4
A control signal for controlling the direction valve 9 is transmitted.
【００３６】次に、冷却系１２による相対湿度分布形成
の作用について説明する。水素供給部１及び空気供給部
２から供給される水素含有ガス及び空気は、加湿器３を
通過し、適当な湿度となった後、燃料電池スタック４の
図中右側から供給される。この水素含有ガス及び空気
は、加湿器３によりある絶対湿度に加湿された後、燃料
電池スタック４の内部を右から左へ流れるに従って、発
電により生成する水分により更に加湿されるので、絶対
湿度が下がることはなく、寧ろ絶対湿度が上がると考え
られる。Next, the operation of forming the relative humidity distribution by the cooling system 12 will be described. The hydrogen-containing gas and the air supplied from the hydrogen supply unit 1 and the air supply unit 2 pass through the humidifier 3, and after being adjusted to an appropriate humidity, are supplied from the right side of the fuel cell stack 4 in the drawing. The hydrogen-containing gas and air are humidified by the humidifier 3 to a certain absolute humidity, and further humidified by the moisture generated by power generation as the gas flows from right to left inside the fuel cell stack 4. It is thought that absolute humidity will rise rather than fall.
【００３７】冷却水方向を切り替える４方弁９は、制御
装置１１からの制御に従って、通常運転時には実線の矢
印方向に冷却水を流し、電圧検出器による電圧検出時に
は、破線の矢印方向に冷却水を流すように切り替える。
これにより燃料電池スタック４を流れる冷却水は、通常
運転時には図中右から左へ流れるので、この時の燃料電
池スタック４内の温度分布は、図中右側が低く、左側が
高くなる。The four-way valve 9 for switching the direction of the cooling water flows the cooling water in the direction indicated by the solid line during normal operation and controls the cooling water in the direction indicated by the broken line when the voltage is detected by the voltage detector, under the control of the controller 11. Switch to flow.
As a result, the cooling water flowing through the fuel cell stack 4 flows from right to left in the figure during normal operation, and the temperature distribution in the fuel cell stack 4 at this time is low on the right side and high on the left side.
【００３８】一方、湿潤状態判定のための電圧測定時に
は、ガスの流れる方向とは反対に図中左から右へ冷却水
が流れるので、この時の燃料電池スタック４内の温度分
布は、通常運転時とは反対に図中右側が高く、左側が低
くなる。従って、電圧測定時の燃料電池スタック４の相
対湿度分布は、図中右側が低く、左側が高くなる。On the other hand, at the time of measuring the voltage for judging the wet state, the cooling water flows from left to right in the figure opposite to the flowing direction of the gas. Contrary to time, the right side in the figure is high and the left side is low. Therefore, the relative humidity distribution of the fuel cell stack 4 at the time of voltage measurement is low on the right side in the figure and high on the left side.
【００３９】このような相対湿度分布を形成した状態
で、燃料電池スタック４の複数セルのそれぞれの温度を
測定すると、測定されたセルの位置に応じて、相対湿度
の低いセルの電圧と、相対湿度の高いセルの電圧とを測
定することになる。When the temperature of each of the plurality of cells of the fuel cell stack 4 is measured in a state where such a relative humidity distribution is formed, the voltage of the cell having a low relative humidity and the voltage of the cell having a low relative humidity are determined in accordance with the position of the measured cell. The voltage of the cell with high humidity will be measured.
【００４０】尚、第１実施形態の変形例として、通常運
転時と湿潤状態判定のための電圧測定時とで冷却水方向
を切り替えることなく、常に燃料電池スタックへのガス
流入方向と冷却水入流方向とを反対方向として、燃料電
池スタックに相対湿度分布が形成されるようにしてもよ
い。この変形例によれば、冷却水方向を切り替える４方
弁を省略して、図２に示す構成となるが、通常運転時の
発電効率に多少の低下が生じるのはやむを得ない。As a modification of the first embodiment, the direction of the gas flowing into the fuel cell stack and the direction of the cooling water flow into the fuel cell stack are always changed without switching the direction of the cooling water between normal operation and voltage measurement for judging the wet state. The direction may be reversed so that a relative humidity distribution is formed in the fuel cell stack. According to this modification, the four-way valve for switching the cooling water direction is omitted, and the configuration shown in FIG. 2 is used. However, it is inevitable that the power generation efficiency during normal operation slightly decreases.
【００４１】次に、第１実施形態の動作を図３のフロー
チャートを参照して説明する。まずステップ（以下、ス
テップをＳと略す）１０１で燃料電池スタック運転中の
電流及び電圧の検出を行う。次いでＳ１０２では、この
検出された電流／電圧の組み合わせが予め記憶してある
電流電圧特性より電圧低下しているかの判定を行い、電
圧低下が認められなければ、Ｓ１０３以下に示した本実
施形態の処理フローを実施することなく、再びＳ１０１
へと戻る。Next, the operation of the first embodiment will be described with reference to the flowchart of FIG. First, in step (hereinafter, step is abbreviated as S) 101, current and voltage during fuel cell stack operation are detected. Next, in S102, it is determined whether or not the detected current / voltage combination is lower than the previously stored current-voltage characteristic. If no voltage lowering is detected, the present embodiment shown in S103 and subsequent steps is executed. Without executing the processing flow, S101 is performed again.
Return to.
【００４２】電圧低下が認められた時は、電圧を適切に
回復すべく、電圧低下の原因を精度よく判定する必要が
あるとし、本実施形態ではＳ１０３で水素や空気といっ
たガスの燃料電池スタック４への入出力方向とは逆方向
に冷却水の循環方向がなるように４方弁９を切り替え
る。この冷却水流入方向の切替により、燃料電池スタッ
ク４内には、上述のようにセル配列方向に相対湿度の分
布が形成される。If a voltage drop is recognized, it is determined that the cause of the voltage drop needs to be accurately determined in order to properly recover the voltage. In the present embodiment, in S103, the fuel cell stack 4 of a gas such as hydrogen or air is used. The four-way valve 9 is switched so that the direction of circulation of the cooling water is opposite to the input / output direction to the cooling water. By the switching of the cooling water inflow direction, the distribution of the relative humidity is formed in the fuel cell stack 4 in the cell arrangement direction as described above.
【００４３】尚、図２に示した第１実施形態の変形例の
ように、燃料電池スタックへの冷却水の流入方向を常に
ガスの流入方向とは逆方向に設定され、冷却水流入方向
を切り替えない構成となっている場合には、このＳ１０
３は省略される。As in the modification of the first embodiment shown in FIG. 2, the flow direction of the cooling water into the fuel cell stack is always set to the opposite direction to the flow direction of the gas, and the flow direction of the cooling water is changed. If the configuration is such that switching is not performed, this S10
3 is omitted.
【００４４】また、Ｓ１０２では電圧低下の有無を判定
し、電圧低下が判定されたときに本ステップ以下を実行
するとしているが、Ｓ１０１、Ｓ１０２を削除して、Ｓ
１０３以下の処理を定期的に実行する構成としてもよ
い。In step S102, the presence or absence of a voltage drop is determined. When the voltage drop is determined, this step and the following steps are executed.
It is also possible to adopt a configuration in which the processes of 103 and below are periodically executed.
【００４５】次いで、セル配列方向に相対湿度の分布が
形成された状態で、Ｓ１０４で燃料電池スタックを構成
する各セルの電圧を電圧検出器で検出し、検出値を制御
装置１１へ伝える。燃料電池スタック４は複数のセルか
ら構成されるが、これら複数個のセル電圧はできるだけ
同一時刻の値を検出できる構成とした方が望ましい。Then, in a state where the relative humidity distribution is formed in the cell array direction, the voltage of each cell constituting the fuel cell stack is detected by the voltage detector in S104, and the detected value is transmitted to the control device 11. The fuel cell stack 4 is composed of a plurality of cells, and it is desirable that the plurality of cell voltages be configured to detect values at the same time as much as possible.
【００４６】次いで、Ｓ１０５では、各セルの位置によ
るセル電圧の傾向を判定し、Ｓ１０６で、電圧低下の原
因が膜の乾燥によるものであるか否かを判定する。Next, in S105, the tendency of the cell voltage depending on the position of each cell is determined, and in S106, it is determined whether or not the cause of the voltage drop is due to drying of the film.
【００４７】図４は、各セル位置に対応するセル電圧分
布の一例であるが、ガス入口側から出口側に向かって各
セルの電圧を順番に並べて表現した図である。この図４
のように、ガス入口側から出口側にかけてセル電圧が高
くなるような傾向が得られた場合には、膜が十分に湿潤
しておらず乾燥状態にあると判断を行う。FIG. 4 is an example of a cell voltage distribution corresponding to each cell position, and is a diagram in which the voltage of each cell is arranged in order from the gas inlet side to the outlet side. This figure 4
When the tendency that the cell voltage increases from the gas inlet side to the outlet side is obtained as in the above, it is determined that the film is not sufficiently wet and is in a dry state.
【００４８】これは、相対湿度の低い部分のセルの電圧
が、相対湿度の高いセルの電圧より低いことを意味して
おり、即ち相対湿度の低い部分のセルの膜が十分に湿潤
しておらず、電圧の低下の原因となっていると判断する
ことが可能である。This means that the voltage of the cell in the low relative humidity part is lower than the voltage of the cell in the high relative humidity part, ie, the membrane of the cell in the low relative humidity part is sufficiently wet. Therefore, it is possible to judge that this is the cause of the voltage drop.
【００４９】また図５に示すようなセル電圧分布が得ら
れた場合、即ち相対湿度の分布とセル電圧の分布とに特
に相関が見られない場合であるが、この場合には膜は十
分に湿潤していると判断する。セル電圧と相対湿度に相
関がない状態では、もしセル電圧が期待値よりも低いと
しても、膜が乾燥しているのではなく、他の原因、例え
ば水素分圧の低下等によるものと判断してよい。In the case where the cell voltage distribution as shown in FIG. 5 is obtained, that is, when there is no particular correlation between the distribution of the relative humidity and the distribution of the cell voltage, in this case, the film is sufficiently formed. Judge that it is wet. In a state where there is no correlation between the cell voltage and the relative humidity, even if the cell voltage is lower than the expected value, it is determined that the film is not dried but is caused by another cause, for example, a decrease in hydrogen partial pressure. May be.
【００５０】尚、本実施形態において図６に示すような
分布が得られた場合、即ちガス入口側の相対湿度の高い
部分のセル電圧が、ガス出口側の相対湿度の低い部分の
セル電圧に対して低いような分布が得られた場合である
が、この場合には、相対湿度の高い部分のセルに水分が
貯まり、反応面積の低減により電圧が低下していると判
断が可能である。In this embodiment, when the distribution as shown in FIG. 6 is obtained, that is, the cell voltage of the gas inlet side where the relative humidity is high is changed to the cell voltage of the gas outlet side where the relative humidity is low. In this case, a low distribution is obtained, but in this case, it is possible to determine that the water is accumulated in the cells of the portion having a high relative humidity and the voltage is lowered due to the reduction of the reaction area.
【００５１】以上のように、電圧低下の原因が膜の乾燥
によるものと判断された場合、燃料電池スタック出力を
制限し、スタック電圧がある設定値以下にならないよう
に制御する（Ｓ１０７〜１０９）、と同時に、燃料電池
制御手段１１へ燃料電池スタックの出力要求を指令する
上位の制御手段（図示せず）に、出力要求可能な上限値
を通知する。As described above, when it is determined that the cause of the voltage drop is due to the drying of the membrane, the output of the fuel cell stack is limited, and control is performed so that the stack voltage does not fall below a certain set value (S107 to 109). At the same time, the upper-order control unit (not shown) instructing the fuel cell control unit 11 to output the fuel cell stack is informed of the upper limit of the output request.
【００５２】これにより上位の制御手段は、燃料電池ス
タックの出し得る電力の最大値を認識しつつ、要求指令
値の演算が可能になるので、予想外に出力されないとい
う状態を防止することができる。This allows the higher-level control means to calculate the required command value while recognizing the maximum value of the power that can be output from the fuel cell stack, thereby preventing a situation in which the output is not performed unexpectedly. .
【００５３】尚、燃料電池スタックの出力制限は、Ｓ１
０４〜Ｓ１０６のように各セル電圧の位置に応じた傾向
により膜の湿潤状態を推定した結果によって行ってもよ
い。Incidentally, the output limitation of the fuel cell stack is S1
It may be performed based on the result of estimating the wet state of the film based on the tendency according to the position of each cell voltage as in 04 to S106.
【００５４】また、燃料電池スタックの電圧や出力の制
御手段であるが、電流制御機能付きのＤＣ／ＤＣコンバ
ータを燃料電池スタックに接続して実施してもよく、詳
細については省略する。The control means for controlling the voltage and output of the fuel cell stack may be implemented by connecting a DC / DC converter having a current control function to the fuel cell stack.
【００５５】また、電圧低下の原因が膜の乾燥以外であ
った場合には、その原因に対応した処理を行うブロック
を実行する。例えば水素極側において窒素濃度が上が
り、その結果水素分圧が低下しているような場合には、
水素極をパージすることで水素分圧を上げるように制御
を行う（Ｓ１１０）。If the cause of the voltage drop is other than the drying of the film, a block for performing processing corresponding to the cause is executed. For example, when the nitrogen concentration increases on the hydrogen electrode side and the hydrogen partial pressure decreases as a result,
Control is performed to increase the hydrogen partial pressure by purging the hydrogen electrode (S110).
【００５６】一例としては、水素が循環系である場合に
は、燃料電池スタックからの排水素を戻すことなくシス
テム外部に排出し、また同時に水素流量を増大させるこ
とで水素極パージが可能であるが、本発明の本質でない
ので、詳細は省略する。As an example, when hydrogen is circulated, it is possible to purge hydrogen from the fuel cell stack without returning it to the outside of the system without returning the hydrogen, and at the same time increase the hydrogen flow rate to purge the hydrogen electrode. However, the details are omitted because they are not the essence of the present invention.
【００５７】〔第２の実施形態〕本実施形態の構成は第
１の実施形態を示す図１と同一である。尚、本実施形態
においては、ガスの流入方向と冷却水の流入方向を必ず
しも逆にする必要はないので、４方弁９を省略すること
ができる。[Second Embodiment] The structure of this embodiment is the same as that of FIG. 1 showing the first embodiment. In the present embodiment, the flow direction of the gas and the flow direction of the cooling water do not necessarily need to be reversed, so that the four-way valve 9 can be omitted.
【００５８】図７に本実施形態のフローチャートを示
す。本実施形態は燃料電池スタックの運転中の電流及び
電圧をある定まった時間以上、あるいは、ある定まった
サンプリング数以上測定し、測定された電流及び電圧か
ら内部抵抗値を演算し、その値から膜の乾燥状態を推定
するものである。FIG. 7 shows a flowchart of the present embodiment. In the present embodiment, the current and voltage during operation of the fuel cell stack are measured for a certain time or more, or a certain number of samplings or more, the internal resistance value is calculated from the measured current and voltage, and the membrane is calculated from the value. This is for estimating the dry state.
【００５９】ここでいう内部抵抗値とは図１０（ａ）に
示す電流−電圧特性における中間部分の傾きに相当す
る。膜の水分量が減少するに従い、イオン伝導度が低下
し、電気抵抗の増大のような形で観測される。The internal resistance value here corresponds to the gradient of the middle part in the current-voltage characteristic shown in FIG. As the water content of the membrane decreases, the ionic conductivity decreases and is observed in the form of an increase in electrical resistance.
【００６０】即ち、十分湿潤していれば、図１０（ａ）
における最も高い電圧を示す特性（以下、標準特性とす
る）となるが、乾燥気味になるにつれ、同じ電流値を燃
料電池スタックから引き出した時の電圧が低下し、略直
線部の傾きが急となり、結果、電流−電圧特性は左下の
ような形へと推移することになる。That is, if it is sufficiently moist, FIG.
(Hereinafter referred to as the standard characteristics), but as the air becomes dry, the voltage when the same current value is drawn from the fuel cell stack decreases, and the slope of the substantially linear portion becomes steep. As a result, the current-voltage characteristic changes to the form as shown in the lower left.
【００６１】またこの略直線部の傾きが標準特性のそれ
と同じであるが、ある電流値以上を取り出した時にの
み、急激に電圧の低下が認められた場合（図１０
（ｂ））は、膜の湿潤状態は適当だが、ガスの状態（流
量や圧力）が取り出した電流に対して適切ではないと判
断を行う。The slope of the substantially linear portion is the same as that of the standard characteristic, but a sharp drop in voltage is recognized only when a current value or more is taken out (FIG. 10).
In (b)), it is determined that the wet state of the film is appropriate, but the state of the gas (flow rate and pressure) is not appropriate for the extracted current.
【００６２】また図１０（ａ）と図１０（ｂ）の状態が
同時に発生する場合には、図１０（ｃ）に示すような電
圧電流特性となり、略直線部の傾きが標準特性より急
で、かつ、ある電流値以上を取り出した時、特性が直線
から外れて電圧が低下した場合には、膜の湿潤が不足気
味であり、かつ、ガスの状態が適切でないと判断するこ
とができる。When the states of FIG. 10A and FIG. 10B occur simultaneously, the voltage-current characteristic becomes as shown in FIG. 10C, and the inclination of the substantially straight line portion is steeper than the standard characteristic. In addition, when a characteristic value deviates from a straight line and a voltage drops when a current value or more is taken out, it can be determined that the film is slightly wet and the gas state is not appropriate.
【００６３】以下に、燃料電池スタックの運転中に測定
された電圧電流特性に基づいて内部抵抗を求める図７の
フローチャートを説明する。Hereinafter, the flowchart of FIG. 7 for obtaining the internal resistance based on the voltage-current characteristics measured during the operation of the fuel cell stack will be described.
【００６４】まずＳ２０１で略同時刻の燃料電池スタッ
クの電流及び電圧を検出する。このタイミングはできる
だけ同時刻の方が望ましい。次いでＳ２０２では検出し
た電流の値によってデータのフィルタリングを行う。こ
れは極小電流域での特性は内部抵抗の影響が出ていない
為、そのような領域のデータをカットする為である。Ｓ
２０３では、後述する内部抵抗演算で参照するために、
測定した電流及び電圧の組データを記録手段に記録す
る。First, in S201, the current and voltage of the fuel cell stack at approximately the same time are detected. It is desirable that this timing be the same as possible. Next, in S202, data filtering is performed according to the detected current value. This is because the characteristics in the minimal current region are not affected by the internal resistance, so that data in such a region is cut. S
In 203, in order to refer to the internal resistance calculation described later,
The set data of the measured current and voltage is recorded in the recording means.
【００６５】Ｓ２０４では、記録された電流及び電圧の
組データが、内部抵抗算出に十分なものかどうかを判定
する。十分と判定する条件として、電流値が広範囲に十
分散らばっていること、組データ数がある設定値以上記
録されていること、等がある。Ｓ２０５では実際に内部
抵抗を演算する。具体的には複数個の電流及び電圧の組
データを直線で近似し、その直線の傾きから求める。In S204, it is determined whether or not the recorded data of the set of current and voltage is sufficient for calculating the internal resistance. Conditions for judging that the current values are sufficient include that the current values are widely dispersed over a wide range, that the number of sets of data is greater than a certain set value, and the like. In S205, the internal resistance is actually calculated. Specifically, a plurality of sets of current and voltage are approximated by a straight line, and are obtained from the slope of the straight line.
【００６６】尚、複数個の電流／電圧の組データを直線
で近似する方法については、各組データを示す点から近
似直線までの距離の２乗の合計が最小となる近似直線を
求める最小２乗法や、例えば特開平６−１７４８０８号
公報に示された方法等がある。As for the method of approximating a plurality of current / voltage set data with a straight line, the method of calculating an approximate straight line that minimizes the sum of the squares of the distances from the points indicating each set data to the approximate straight line is used. There is a multiplication method, a method disclosed in, for example, JP-A-6-174808, and the like.
【００６７】以上のような方法で求めた略直線部の傾き
と、予め実験等で求めておいた標準特性とを比較し、傾
きが急な場合には膜が乾燥していると判断し、出力の制
限を行う等の処理を行い、スタックの劣化等悪影響を抑
えることが可能となる。また略直線部の傾きが、標準特
性のそれと略同一で、ある電流値以上の場合に電圧の低
下が認められる時は、ガス条件に問題があるとし、パー
ジ処理を行うことで水素極に蓄積された窒素を排出し、
水素分圧を回復し、電圧の標準特性に戻すことが可能と
なる。The inclination of the substantially linear portion obtained by the above method is compared with a standard characteristic obtained in advance by an experiment or the like. If the inclination is steep, it is determined that the film is dry. By performing processing such as limiting the output, it is possible to suppress adverse effects such as deterioration of the stack. If the slope of the substantially linear portion is substantially the same as that of the standard characteristics, and if a decrease in voltage is observed at a certain current value or more, it is determined that there is a problem with the gas conditions, and purging is performed to accumulate in the hydrogen electrode. Discharge the nitrogen
It is possible to restore the hydrogen partial pressure and return to the standard characteristics of the voltage.
【００６８】尚、燃料電池の内部抵抗は、電極の抵抗、
電解質のイオン導電度等、温度特性を有するので、例え
ば冷却水温を測定する温度計１０の測定結果に応じて、
内部抵抗の標準値を変更することが好ましい。具体的に
は、実験的に求めたマップや、補正計算式を用いる。The internal resistance of the fuel cell is the resistance of the electrode,
Since it has temperature characteristics such as the ionic conductivity of the electrolyte, for example, according to the measurement result of the thermometer 10 that measures the cooling water temperature,
It is preferable to change the standard value of the internal resistance. Specifically, an experimentally determined map or a correction calculation formula is used.
【００６９】〔第３の実施形態〕図８は、本発明に係る
燃料電池の第３の実施形態の構成を示す全体構成図であ
る。本実施形態は、図１に示した第１の実施形態に対
し、４方弁９を削除して燃料電池スタック４への冷却水
流入方向をガス流入方向と常に同一とし、水素含有ガス
及び空気の燃料電池スタック入出力部に水分流量検出手
段を設けた例である。[Third Embodiment] FIG. 8 is an overall configuration diagram showing the configuration of a third embodiment of the fuel cell according to the present invention. This embodiment is different from the first embodiment shown in FIG. 1 in that the four-way valve 9 is eliminated so that the cooling water inflow direction to the fuel cell stack 4 is always the same as the gas inflow direction, and the hydrogen-containing gas and air This is an example in which a moisture flow detecting means is provided in the fuel cell stack input / output unit.
【００７０】即ち燃料電池スタック４へ水素供給部１か
ら流入する水分流量を検出する水分流量検出手段２１
と、水素出口から流出する水分流量を検出する水分流量
検出手段２２と、空気供給部２から流入する水分流量を
検出する水分流量検出手段２３と、空気出口のから流出
する水分流量を検出する水分流量検出手段２４とを設け
ている。これらの水分流量検出手段２１、２２、２３、
２４としては、例えば鏡面冷却式等の露点検出手段と、
質量流量検出手段で構成することが可能である。That is, a water flow rate detecting means 21 for detecting the flow rate of water flowing from the hydrogen supply unit 1 into the fuel cell stack 4
A moisture flow rate detecting means 22 for detecting a moisture flow rate flowing out of the hydrogen outlet, a moisture flow rate detecting means 23 for detecting a moisture flow rate flowing from the air supply unit 2, and a moisture detecting means for detecting a moisture flow rate flowing out of the air outlet. A flow detecting means 24 is provided. These water flow rate detecting means 21, 22, 23,
As 24, for example, a dew point detecting means such as a mirror surface cooling type,
It is possible to configure with mass flow rate detecting means.
【００７１】また制御装置１１では、燃料電池スタック
４から取り出した電流値に応じて燃料電池スタック内部
で生成された水分量を演算する手段が設けられている。The control device 11 is provided with means for calculating the amount of moisture generated inside the fuel cell stack according to the current value taken out of the fuel cell stack 4.
【００７２】燃料電池スタック４の入口の水素及び空気
中の水分流量合計にスタック内部で生成された水分量を
加えた値に対し、燃料電池スタック出口の水素及び空気
中の水分流量合計が大きければ、膜から水分のガス中に
出ていることを示し、即ち膜が乾燥傾向にあることを示
している。If the sum of the flow rates of hydrogen and air at the outlet of the fuel cell stack is larger than the sum of the flow rates of hydrogen and air at the inlet of the fuel cell stack 4 plus the amount of water generated inside the stack, , Indicating that the film is coming out of the moisture gas, that is, the film has a tendency to dry.
【００７３】逆に出口の水素及び空気中の水分量合計が
小さければ、膜にガス中から水分が浸透していることに
なり、即ち膜が湿潤傾向にあることがわかる。よって、
この水分の変化量を積分することにより燃料電池スタッ
ク内の平均的湿潤程度を推定することができるようにな
る。Conversely, if the total amount of hydrogen at the outlet and the amount of water in the air is small, it means that water has penetrated the gas from the gas, that is, the film has a tendency to wet. Therefore,
By integrating the amount of change in the water content, the average degree of wetness in the fuel cell stack can be estimated.
【図１】本発明に係る燃料電池の第１の実施形態の構成
を示す全体構成図である。FIG. 1 is an overall configuration diagram showing a configuration of a first embodiment of a fuel cell according to the present invention.
【図２】第１実施形態の変形例の構成を示す全体構成図
である。FIG. 2 is an overall configuration diagram showing a configuration of a modification of the first embodiment.
【図３】第１の実施形態の動作を説明するフローチャー
トである。FIG. 3 is a flowchart illustrating the operation of the first embodiment.
【図４】不十分な湿潤状態におけるセル位置に対するセ
ル電圧分布例を示す図である。FIG. 4 is a diagram illustrating an example of a cell voltage distribution with respect to a cell position in an insufficiently wet state.
【図５】適度な湿潤状態におけるセル位置に対するセル
電圧分布例を示す図である。FIG. 5 is a diagram showing an example of a cell voltage distribution with respect to a cell position in an appropriate wet state.
【図６】過剰な湿潤状態におけるセル位置に対するセル
電圧分布例を示す図である。FIG. 6 is a diagram showing an example of a cell voltage distribution with respect to a cell position in an excessively wet state.
【図７】第２の実施形態の動作を説明するフローチャー
トである。FIG. 7 is a flowchart illustrating the operation of the second embodiment.
【図８】本発明に係る燃料電池の第３の実施形態の構成
を示す全体構成図である。FIG. 8 is an overall configuration diagram showing a configuration of a third embodiment of the fuel cell according to the present invention.
【図９】（ａ）膜中の水分が減少した場合、（ｂ）水素
分圧が低下した場合、（ｃ）膜中の水分が減少した状態
で水素分圧が低下した場合のそれぞれ燃料電池の電流−
電圧特性の代表例を示す図である。FIGS. 9A and 9B show fuel cells in the case where (a) the water content in the membrane is reduced, (b) the hydrogen partial pressure is reduced, and (c) the hydrogen partial pressure is reduced in a state where the water content in the membrane is reduced. Current
FIG. 4 is a diagram illustrating a representative example of voltage characteristics.
１ 水素供給部 ２ 空気供給部 ３ 加湿器 ４ 燃料電池スタック ５ 燃料循環用ポンプ ６ 逆止弁 ７ 冷却水ポンプ ８ ラジエータ ９ ４方弁 １０ 温度計 １１ 制御装置 １２ 冷却系 DESCRIPTION OF SYMBOLS 1 Hydrogen supply part 2 Air supply part 3 Humidifier 4 Fuel cell stack 5 Fuel circulation pump 6 Check valve 7 Cooling water pump 8 Radiator 9 Four-way valve 10 Thermometer 11 Control device 12 Cooling system
Claims (9)
から選ばれた少なくとも２つのセルの電圧を検出する電
圧検出手段と、 少なくとも前記電圧検出手段によるセル電圧検出時に、
燃料電池スタックのセル配列方向に燃料ガス及び酸化ガ
スの相対湿度分布を形成する湿度分布形成手段と、 前記電圧検出手段が検出した各セル毎の電圧分布を調べ
て、相対湿度が低いセルの電圧が相対湿度が高いセルの
電圧に比べて低い場合に、燃料電池の湿潤が不十分と判
定する湿潤状態判定手段と、 を備えたことを特徴とする燃料電池。1. A voltage detecting means for detecting a voltage of at least two cells selected from a plurality of cells constituting a fuel cell stack, and at least a cell voltage is detected by the voltage detecting means.
A humidity distribution forming means for forming a relative humidity distribution of the fuel gas and the oxidizing gas in the cell array direction of the fuel cell stack; and examining a voltage distribution of each cell detected by the voltage detecting means, a voltage of a cell having a low relative humidity. A fuel cell comprising: a wet state determination unit that determines that the fuel cell is not sufficiently wet when the relative humidity is lower than the voltage of a cell having a high relative humidity.
と冷却水流入方向とを通常運転時には同方向とする一
方、前記湿潤状態判定手段による湿潤状態判定のための
前記電圧検出手段による電圧検出時には逆方向に切り替
えることで、燃料電池スタックのセル配列方向に燃料ガ
ス及び酸化ガスの相対湿度分布を形成する冷却手段であ
ることを特徴とする請求項１記載の燃料電池。2. The humidity distribution forming means sets the flow direction of the fuel gas and the oxidizing gas into the fuel cell stack and the flow direction of the cooling water to be the same during normal operation, while determining the wet state by the wet state determining means. 2. A cooling means for forming a relative humidity distribution of a fuel gas and an oxidizing gas in a cell array direction of a fuel cell stack by switching in a reverse direction when a voltage is detected by the voltage detecting means. The fuel cell as described.
と冷却水流入方向とを常に逆方向とし、燃料電池スタッ
クのセル配列方向に燃料ガス及び酸化ガスの相対湿度分
布を形成する冷却手段であることを特徴とする請求項１
記載の燃料電池。3. The fuel cell system according to claim 2, wherein the humidity distribution forming means always reverses a direction in which the fuel gas and the oxidizing gas flow into the fuel cell stack and a direction in which the cooling water flows into the fuel cell stack. 2. A cooling means for forming a relative humidity distribution as described above.
The fuel cell as described.
を測定する電圧電流測定手段と、 該電圧電流測定手段が測定した電圧電流特性に基づい
て、燃料電池スタックの内部抵抗値を推定する内部抵抗
推定手段と、 前記推定された内部抵抗値と予め記憶した標準値との比
較に基づいて、燃料電池の湿潤状態を判定する湿潤状態
判定手段と、 該湿潤状態判定手段が湿潤が不十分と判定したとき、燃
料電池の出力を制限する出力制限手段と、 を備えたことを特徴とする燃料電池。4. A voltage / current measuring means for measuring a voltage and a current during operation of the fuel cell stack, and an internal for estimating an internal resistance value of the fuel cell stack based on the voltage / current characteristics measured by the voltage / current measuring means. Resistance estimating means, wet state judging means for judging the wet state of the fuel cell based on a comparison between the estimated internal resistance value and a pre-stored standard value; And a power limiting means for limiting the output of the fuel cell when the determination is made.
と、 測定された温度に基づいて前記標準値を変更する標準値
変更手段と、 を更に備えたことを特徴とする請求項４記載の燃料電
池。5. The apparatus according to claim 4, further comprising: temperature measuring means for measuring the temperature of the fuel cell; and standard value changing means for changing the standard value based on the measured temperature. Fuel cell.
び酸化ガスの水分量を検出する流入水分量検出手段と、 燃料電池スタックから流出する燃料ガス及び酸化ガスの
水分量を検出する流出水分量検出手段と、 燃料電池スタック内部で生成された水分量を推定する生
成水分量推定手段と、 前記生成された水分量及び流入水分量及び流出水分量に
基づいて燃料電池の湿潤状態を判定する湿潤状態判定手
段と、 を備えたことを特徴とする燃料電池。6. An inflow water amount detecting means for detecting a water amount of a fuel gas and an oxidizing gas flowing into the fuel cell stack, and an outflow water amount detection for detecting a water amount of the fuel gas and the oxidizing gas flowing out of the fuel cell stack. Means, a generated water amount estimating means for estimating the amount of water generated inside the fuel cell stack, and a wet state for determining a wet state of the fuel cell based on the generated water amount, the inflow water amount, and the outflow water amount. A fuel cell, comprising: a determination unit.
判定したとき、燃料電池の出力を制限する出力制限手段
を更に備えたことを特徴とする請求項１ないし請求項６
のいずれか１項記載の燃料電池。7. The fuel cell system according to claim 1, further comprising an output limiting unit that limits an output of the fuel cell when the wet state determining unit determines that the wetness is insufficient.
The fuel cell according to claim 1.
ガス及び酸化ガスの相対湿度分布を形成する湿度分布形
成過程と、 燃料電池スタックを構成する複数のセルから選ばれた少
なくとも２つのセルの電圧を検出する電圧検出過程と、 各セル毎の電圧分布を調べて、相対湿度が低いセルの電
圧が相対湿度が高いセルの電圧に比べて低い場合に、燃
料電池の湿潤が不十分と判定する湿潤状態判定過程と、 前記湿潤状態判定過程で湿潤が不十分と判定したとき、
燃料電池の出力を制限する出力制限過程と、 を備えたことを特徴とする燃料電池の運転方法。8. A humidity distribution forming step of forming a relative humidity distribution of a fuel gas and an oxidizing gas in a cell array direction of a fuel cell stack, and a voltage of at least two cells selected from a plurality of cells constituting the fuel cell stack. A voltage detection process for detecting the cell, and examining a voltage distribution of each cell, and when the voltage of the cell having a low relative humidity is lower than the voltage of the cell having a high relative humidity, it is determined that the fuel cell is not sufficiently wet. Wet state determination step, when it is determined that the wet state is insufficient in the wet state determination step,
A method for operating a fuel cell, comprising: an output limiting step of limiting the output of the fuel cell.
を測定する電圧電流測定過程と、 前記測定された電圧電流特性に基づいて、燃料電池スタ
ックの内部抵抗値を推定する内部抵抗推定過程と、 前記推定された内部抵抗値と予め記憶した標準値との比
較に基づいて、燃料電池の湿潤状態を判定する湿潤状態
判定過程と、 前記湿潤状態判定過程で湿潤が不十分と判定したとき、
燃料電池の出力を制限する出力制限過程と、 を備えたことを特徴とする燃料電池の運転方法。9. A voltage / current measuring step of measuring voltage and current during operation of the fuel cell stack; an internal resistance estimating step of estimating an internal resistance value of the fuel cell stack based on the measured voltage / current characteristics. A wet state determination step of determining a wet state of the fuel cell based on a comparison between the estimated internal resistance value and a previously stored standard value, and when it is determined that the wetness is insufficient in the wet state determination step,
A method for operating a fuel cell, comprising: an output limiting step of limiting the output of the fuel cell.
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