JP2004170146A - Insulation detecting apparatus of non-grounded power supply - Google Patents

Insulation detecting apparatus of non-grounded power supply Download PDF

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JP2004170146A
JP2004170146A JP2002334095A JP2002334095A JP2004170146A JP 2004170146 A JP2004170146 A JP 2004170146A JP 2002334095 A JP2002334095 A JP 2002334095A JP 2002334095 A JP2002334095 A JP 2002334095A JP 2004170146 A JP2004170146 A JP 2004170146A
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switch
voltage
capacitor
power supply
abnormality
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JP3890503B2 (en
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Masashi Taniguchi
誠志 谷口
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Yazaki Corp
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Yazaki Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulation detecting apparatus for an ungrounded power supply for specifying a switch that has failed. <P>SOLUTION: A failure detection means is in the following configuration. After only a second switch section S2 is closed for third set time, an abnormality of a first switch section S1 is judged, based on a detection voltage by a voltage detection means 11 when fourth switching means S3, S4 are closed. After only the first switch section S1 is closed for fourth setting time, an abnormality of the second switch section S2 is judged, based on a detection voltage by the voltage detection means when the fourth switching means S3, S4 are closed. After the first switching means S1, S2 are closed for fifth setting time, an abnormality of the third switching section S3 is judged, based on the detection voltage by the voltage detection means 11 when the third switch section S3 is broken and the fourth switch section S4 is closed. After the first switching means S1, S2 are closed for sixth setting time, an abnormality of the fourth switch section S4 is detected, based on the detection voltage by the voltage detection means 11 when the third switch section S3 is closed and the fourth switch section S4 is broken. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、非接地電源の絶縁検出装置に係り、特に、電気による推進力を利用する車両に搭載された非接地の直流電源に好適な絶縁検出装置に関する。
【０００２】
【従来の技術】
非接地電源の絶縁検出装置は、非接地の直流電源の正及び負端子に接続され、接地電位部からは絶縁された正及び負側の主回路配線の接地電位部に対する絶縁抵抗つまり地絡抵抗を検出することで、接地電位部に対する絶縁や地絡状態を検出するものである（例えば、特許文献１参照）。このような従来の絶縁検出装置では、非接地の直流電源の正端子と接地電位部との間にコンデンサを直列に設定時間の間接続するスイッチング手段、非接地の電源の負端子と接地電位部との間にコンデンサを直列に設定時間の間接続するスイッチング手段、各スイッチング手段の遮断後にコンデンサの両端子間の電圧を検出する検出手段を接続する検出用のスイッチング手段、検出手段で検出した各スイッチング手段の遮断後のコンデンサの両端子間電圧とコンデンサを完全に充電することによって予め算出しておいた電源電圧とに基づいて電源の接地電位部に対する絶縁抵抗つまり地絡抵抗を求める演算手段などを備えており、演算手段で求められた地絡抵抗から絶縁状態の検出や判定などを行っている。
【０００３】
このような絶縁検出装置では、地絡抵抗を求める際、コンデンサの容量などを定数として含む式を用いるが、定数として用いるコンデンサの容量などには、製品間における容量などのばらつきや温度変化による容量のばらつきなどが存在し、さらに容量などの経時変化などが生じる場合もある。このように定数として用いる値にばらつきや変化がある場合、求めた地絡抵抗の値と実際の地絡抵抗の値との間の計測誤差が増大するため、絶縁状態の検出精度が低下してしまう。したがって、コンデンサの容量など地絡抵抗を求める際の定数となる値にばらつきや変化などがあっても、地絡抵抗の計測誤差をできるだけ低減し、絶縁状態の検出精度を向上することが望まれている。
【０００４】
そこで本願の発明者らは、正端子側及び負端子側の配線が接地電位部から絶縁された直流電源にコンデンサを直列に第１の設定時間の間接続する第１のスイッチング手段と、電源の正端子と接地電位部との間にコンデンサを直列に第２の設定時間の間接続する第２のスイッチング手段と、電源の負端子と接地電位部との間にコンデンサを直列に第２の設定時間の間接続する第３のスイッチング手段と、第１、第２及び第３の各スイッチング手段の遮断後にコンデンサの両端子間の電圧を検出する電圧検出手段を接続する第４のスイッチング手段と、第１のスイッチング手段を遮断後の電圧検出手段での検出電圧に基づいて電源の電源電圧を推定し、この推定した電源電圧と第２及び第３のスイッチング手段を遮断後の検出手段での各検出電圧とに基づいて電源の接地電位部に対する絶縁抵抗を求める演算手段とを備えた構成の絶縁検出装置を考えている。
【０００５】
このような構成の絶縁検出装置とすることにより、コンデンサを完全に充電するのに要する時間よりも短い時間で設定した第１の設定時間の間第１のスイッチング手段によって直流電源と接地電位部との間にコンデンサが直流に接続されて充電される。このときのコンデンサの両端端子間の電圧を第４のスイッチング手段によって接続された検出手段で検出し、この検出した電圧から演算手段が電源電圧を推定し、この電源電圧と、第２及び第３のスイッチング手段遮断後の検出手段での検出電圧とに基づいて接地電位部に対する絶縁抵抗を求めることで、絶縁抵抗の計測誤差を低減し、絶縁状態の検出精度を向上できる。
【０００６】
ところで、このような絶縁検出装置では、各スイッチング手段に異常が生じてしまうと、誤った地絡抵抗値を求めることになるため、得られた地絡抵抗値が絶縁状態の不良によるものかスイッチング手段の異常によるものかがわからない。このため、本願の発明者らは、絶縁状態の検出過程においてスイッチング手段の異常を検出するのに、第１のスイッチング手段によって電源にコンデンサを直列に接続する前で第１、第２、第３及び第４のスイッチング手段を遮断した状態から、第１のスイッチング手段の遮断後に第４のスイッチング手段によって電圧検出手段を接続した後、第４のスイッチング手段を遮断するまでの間に電圧検出手段で検出した検出電圧に基づいて第１、第２、第３及び第４のスイッチング手段の異常を検出する異常検出手段を備えた構成とすることを考えている。
【０００７】
このとき、第１のスイッチング手段によって電源にコンデンサを直列に接続する前で第１、第２、第３及び第４のスイッチング手段を遮断した状態から、第１のスイッチング手段の遮断後に第４のスイッチング手段によって電圧検出手段を接続した後、第４のスイッチング手段を遮断するまでの間、すなわち電源の電源電圧を推定する過程において検出手段で得られる検出電圧は、絶縁状態つまり地絡抵抗に影響されない値である。このため、上記ような電源の電源電圧を推定する過程における検出手段での検出電圧に基づいて異常を検出する異常検出手段を備えた構成とすることにより、絶縁状態の計測過程においてスイッチング手段の異常を検出できる。
【特許文献１】
特開平８−２２６９５０号公報（第４−７頁、第１図）
【０００８】
【発明が解決しようとする課題】
しかし、上記のような異常検出手段を備えた絶縁検出装置では、各スイッチング手段が２つのスイッチ部を含む回路構成となる場合、すなわち、第１のスイッチング手段が、電源の正端子に接続された第１のスイッチ部と、電源の負端子に接続された第２のスイッチ部とを含み、第３のスイッチング手段が、第２のスイッチ部と、第１のスイッチに直列に接続された第３のスイッチ部とを含み、第２のスイッチング手段が、第１のスイッチ部と、第２のスイッチ部に直列に接続された第４のスイッチ部とを含み、第４のスイッチング手段が、第３のスイッチ部と第４のスイッチ部とを含み、第１のスイッチ部と第３のスイッチ部との間と、第２のスイッチ部Ｓ２と第４のスイッチ部との間とに、正側から負側に向かう方向に整流する第１のダイオード、第１の抵抗及びコンデンサを直列に接続し、第１のダイオード及び第１の抵抗に並列に、この第１ダイオードと逆方向に整流する第２のダイオード及び第２の抵抗を直列に接続し、検出手段を第３のスイッチ部と第４のスイッチ部との間に接続し、検出手段と第４のスイッチ部との間を接地電位部に接地した回路構成となっている場合、異常検出手段が２つのスイッチ部つまりスイッチを組み合わせて異常の検出を行うため、異常が発生したスイッチング手段または２つのスイッチの組みを特定することはできるが、２つのスイッチのうち、いずれに異常があるのかを特定することはできない。
【０００９】
このように、各スイッチング手段が２つのスイッチ部つまりスイッチを含む回路構成となる場合、従来考えられていた絶縁検出装置の異常検出手段では、異常が発生したスイッチを特定できないため、異常の発生に対する対処を迅速に行えないといった問題が生じる場合がある。このため、異常が発生したスイッチを特定することが課題となっている。
【００１０】
本発明の課題は、異常が発生したスイッチを特定することにある。
【００１１】
【課題を解決するための手段】
本発明の絶縁検出装置は、正端子側及び負端子側の配線が接地電位部から絶縁された直流電源にコンデンサを直列に、このコンデンサが完全に充電される時間よりも短い第１の設定時間の間接続する第１のスイッチング手段と、電源の正端子と接地電位部との間にコンデンサを直列に第２の設定時間の間接続する第２のスイッチング手段と、電源の負端子と接地電位部との間にコンデンサを直列に第２の設定時間の間接続する第３のスイッチング手段と、第１、第２及び第３の各スイッチング手段の遮断後にコンデンサの両端子間の電圧を検出する電圧検出手段を接続する第４のスイッチング手段と、第１のスイッチング手段を遮断後の電圧検出手段での検出電圧に基づいて電源の電源電圧を推定し、この推定した電源電圧と第２及び第３のスイッチング手段を遮断後の電圧検出手段での各検出電圧とに基づいて電源の接地電位部に対する絶縁抵抗を求める演算手段と、第１、第２、第３及び第４のスイッチング手段で生じた異常を検出する異常検出手段とを備え、第１のスイッチング手段が、電源の正端子に接続された第１のスイッチ部と、電源の負端子に接続された第２のスイッチ部とを含み、第３のスイッチング手段が、第２のスイッチ部と、第１のスイッチに直列に接続された第３のスイッチ部とを含み、第２のスイッチング手段が、第１のスイッチ部と、第２のスイッチ部に直列に接続された第４のスイッチ部とを含み、第４のスイッチング手段が、第３のスイッチ部と第４のスイッチ部とを含み、第１のスイッチ部と第３のスイッチ部との間と、第２のスイッチ部と第４のスイッチ部との間とに、正側から負側に向かう方向に整流する第１のダイオード及びコンデンサを直列に接続し、第１のダイオードに並列に、この第１ダイオードと逆方向に整流する第２のダイオードを接続し、電圧検出手段を第３のスイッチ部と第４のスイッチ部との間に接続し、電圧検出手段と第４のスイッチ部との間を接地電位部に接地しており、異常検出手段は、第２のスイッチ部のみを第３の設定時間の間閉路した後、第４のスイッチング手段を閉路したときの電圧検出手段での検出電圧に基づいて第１のスイッチ部の異常を判定し、第１のスイッチ部のみを第４の設定時間の間閉路した後、第４のスイッチング手段を閉路したときの電圧検出手段での検出電圧に基づいて第２のスイッチ部の異常を判定し、第１のスイッチング手段を第５の設定時間の間閉路した後、第３のスイッチ部を遮断及び第４のスイッチ部を閉路したときの電圧検出手段での検出電圧に基づいて第３のスイッチ部の異常を判定し、第１のスイッチング手段を第６の設定時間の間閉路した後、第３のスイッチ部を閉路及び第４のスイッチ部を遮断したときの電圧検出手段での検出電圧に基づいて第４のスイッチ部の異常を検出する構成とすることにより上記課題を解決する。
【００１２】
このような構成とすることにより、異常検出手段が、第１、第２、第３及び第４の各スイッチング手段を構成している第１、第２、第３及び第４の各スイッチ部を個別に検査して異常を判定するため、異常が発生したスイッチを特定できる。
【００１３】
【発明の実施の形態】
以下、本発明を適用してなる絶縁検出装置の一実施形態について図１乃至図１０を参照して説明する。図１は、本発明を適用してなる絶縁検出装置の概略構成を示す図である。図２は、本発明を適用してなる絶縁検出装置の絶縁抵抗計測動作を示すフロー図である。図３は、本発明を適用してなる絶縁検出装置の絶縁抵抗の計測工程における電源電圧推定過程の動作を示すフロー図である。図４は、電源電圧正常時及び異常時の各スイッチ部の動作に対するコンデンサの充放電状態と電圧の読み込みタイミングを示すタイムチャートである。図５は、第２スイッチの異常検出過程の各スイッチ部の動作に対するコンデンサの充放電状態と電圧の読み込みタイミングを示すタイムチャートである。図６は、第１スイッチの異常検出過程の各スイッチ部の動作に対するコンデンサの充放電状態と電圧の読み込みタイミングを示すタイムチャートである。図７は、第３スイッチの異常検出過程の各スイッチ部の動作に対するコンデンサの充放電状態と電圧の読み込みタイミングを示すタイムチャートである。図８は、第４スイッチの異常検出過程の各スイッチ部の動作に対するコンデンサの充放電状態と電圧の読み込みタイミングを示すタイムチャートである。図９は、本発明を適用してなる絶縁検出装置の絶縁抵抗計測過程の動作を示すフロー図である。図１０は、絶縁抵抗の値に対する各電源電圧の計測時間で検出した絶縁抵抗の値の検出誤差を示す図である。なお、図４のタイムチャートでは、スイッチ異常検出過程の検出電圧ＶＣ及びＡ／Ｄ変換値は、スイッチに異常がない場合の状態を示し、図５乃至図８のタイムチャートでは、スイッチ異常検出過程の検出電圧ＶＣ及びＡ／Ｄ変換値は、スイッチに異常がある場合の状態を示している。
【００１４】
本実施形態の絶縁検出装置１は、図１に示すように、例えば電力を利用して推進力を得る電気推進車両などの電力源となる直流電源３に対して適用したものである。電源３は、複数の蓄電池などを直列接続したものであり、電源３の正端子側の正側主回路配線５ａと負端子側の負側主回路配線５ｂが、各々、接地電位部７、例えば車体などから絶縁されており、電源３は非接地電源となっている。絶縁検出装置１は、第１スイッチＳ１、第２スイッチＳ２、第３スイッチＳ３、第４スイッチＳ４、コンデンサ９、電圧検出手段と演算手段を兼ねると共に絶縁状態を判定するマイコン１１、そして各スイッチを設定された時間に応じて開閉制御する図示していないスイッチング制御回路などで構成されている。
【００１５】
なお、本実施形態のマイコン１１は、第１スイッチＳ１、第２スイッチＳ２、第３スイッチＳ３、第４スイッチＳ４などの各スイッチの異常を検出する異常検出手段も兼ねている。さらに、図示していないスイッチング制御回路をマイコン１１に一体に含めるなど、電圧検出手段、演算手段、異常検出手段及びスイッチング制御回路などは、別体または一体に適宜形成できる。また、図１で示した第１スイッチＳ１、第２スイッチＳ２、第３スイッチＳ３、第４スイッチＳ４は、例えばリレーや半導体スイッチといった様々なスイッチ機能を有する部品からなるスイッチ部を接点として模式的に示したものである。
【００１６】
電源３の正端子側には、この正端子側から第１スイッチＳ１及び第３スイッチＳ３が順次直列に接続され、電源３の負端子側には、この負端子側から第２スイッチＳ２、第４スイッチＳ４及び第４抵抗Ｒ４が順次直列に接続されている。第１スイッチＳ１と第３スイッチＳ３との間から第２スイッチＳ２と第４スイッチＳ４との間には、第１ダイオードＤ１、第１抵抗Ｒ１及びコンデンサ９が順次直列に接続されている。第１抵抗Ｒ１とコンデンサ９との間から第１スイッチＳ１と第３スイッチＳ３との間には、第２ダイオードＤ２及び第２抵抗Ｒ２が順次直列に接続されている。すなわち、第１ダイオードＤ１及び第１抵抗Ｒ１と、第２ダイオードＤ２及び第２抵抗Ｒ２とは並列に接続されている。また、第２ダイオードＤ２と第２抵抗Ｒ２との間の部位から接地電位部７に、バイパス手段として、第５スイッチＳ５、そして第２抵抗Ｒ２よりも抵抗が低い第５抵抗Ｒ５が順次直列に接続されている。第１ダイオードＤ１は、正側から負側に向かう方向に整流するものであり、第２ダイオードＤ２は、第１ダイオードＤ１と逆方向に整流するものである。
【００１７】
第３スイッチＳ３と第４抵抗Ｒ４間には、第３スイッチＳ３と第４抵抗Ｒ４に対して直列に第３抵抗Ｒ３が接続されており、第３スイッチＳ３と第３抵抗Ｒ３との間には、検出手段と演算手段を兼ねるマイコン１１がマイコン１１のアナログ／デジタル変換ポートつまりＡ／Ｄポートを介して接続されている。また、第３抵抗Ｒ３と第４抵抗Ｒ４との間の部位は、接地電位部７に接地されている。
【００１８】
したがって、電源３にコンデンサ９を直列に第１の設定時間の間接続する第１のスイッチング手段は、第１スイッチＳ１、第２スイッチＳ２及び図示していないスイッチング制御回路などで、電源３の正端子と接地電位部７との間にコンデンサ９を直列に第２の設定時間の間接続する第２のスイッチング手段は、第１スイッチＳ１、第４スイッチＳ４及び図示していないスイッチング制御回路などで、接地電位部７と電源３の負端子との間にコンデンサ９を直列に第２の設定時間の間接続する第３のスイッチング手段は、第２スイッチＳ２、第３スイッチＳ３及び図示していないスイッチング制御回路などで、第４のスイッチング手段は、第３スイッチＳ３、第４スイッチＳ４及び図示していないスイッチング制御回路などで形成されている。なお、コンデンサ９には、例えば数μＦといった比較的高容量のものが用いられ、第１抵抗Ｒ１と第２抵抗Ｒ２には、例えば数百ｋΩといった比較的高い抵抗値のものが用いられている。
【００１９】
このような構成の絶縁検出装置の動作と本発明の特徴部について説明する。本実施形態の絶縁検出装置１による絶縁状態の計測は、図２に示されるように、電源３の電源電圧を推定するための電源電圧推定過程１０１、電源電圧推定１０１で推定した電源電圧から電源電圧の異常を検出する電源電圧異常判定１０３、電源電圧異常判定１０３で電源電圧が異常と判定された場合に実施される各スイッチＳ２、Ｓ１、Ｓ３、Ｓ４の異常を検出するための第２スイッチ異常検出過程１０５、第１スイッチ異常検出過程１０７、第３スイッチ異常検出過程１０９、第４スイッチ異常検出過程１１１、そして絶縁抵抗計測過程１１３などにより行われる。
【００２０】
電源電圧推定過程１０１では、図３及び図４に示すように、電源電圧推定過程１０１を開始すると、図示していないスイッチング制御回路が第１スイッチＳ１及び第２スイッチＳ２を第１の設定時間である第１閉路時間Ｔ１の間、閉路する（ステップ２０１）。すなわち、第１のスイッチング手段により、接地電位部７を介さずに電源３にコンデンサ９を直列に接続する回路が形成され、第１閉路時間Ｔ１の間、コンデンサ９への充電が行われ、コンデンサ９の両端子間の電圧ＶＣが上昇する。なお、第１閉路時間Ｔ１は、コンデンサ９を完全に充電するのに必要な時間よりも短い時間に設定されており、例えばコンデンサ９を完全に充電するのに必要な時間の１／５〜１／１０といったような短い時間となっており、第１閉路時間Ｔ１は、必要とされる絶縁抵抗の計測誤差範囲によって選択されたものである。
【００２１】
ステップ２０１において第１閉路時間Ｔ１が経過すると、第１スイッチＳ１及び第２スイッチＳ２が開路つまり遮断され、第１閉路時間Ｔ１よりも短い所定時間ｔｗ１経過後、第３スイッチＳ３及び第４スイッチＳ４が閉路される（ステップ２０３）。すなわち、第４のスイッチング手段により、コンデンサ９の両端子間の電圧を検出するマイコン１１が接続された回路が形成されると共に、第２抵抗Ｒ２、第３抵抗Ｒ３、そして第４抵抗Ｒ４を含むコンデンサ９からの放電回路が形成され、コンデンサ９の両端子間の電圧ＶＣが降下する。ここで、マイコン１１は、Ａ／Ｄポートを介してＡ／Ｄ変換データ、つまりコンデンサ９の両端子間の電圧ＶＣを読み込む（ステップ２０５）。このときのコンデンサ９の両端子間電圧ＶＣの値つまり検出電圧Ｖ０により、次式（１）から推定の電源電圧Ｖ０ｓを算出する（ステップ２０７）。
Ｖ０ｓ＝Ｖ０／（１−ＥＸＰ（−Ｔ１／Ｃ・Ｒ１）） …（１）
ただし、式（１）において、Ｔ１は第１スイッチＳ１及び第２スイッチＳ２の閉路時間、Ｃはコンデンサ９の容量、Ｒ１は第１抵抗Ｒ１の抵抗値である。
【００２２】
一方、図示していないスイッチング制御回路は、ステップ２０５でコンデンサ９の両端子間の電圧ＶＣを検出した後、第３スイッチＳ３及び第４スイッチＳ４が閉路された状態で、第５スイッチＳ５を閉路して第２抵抗Ｒ２をバイパスさせることで、第２抵抗Ｒ２の抵抗値を下げた状態とし、コンデンサ９からの放電に要する時間を短縮する。第５スイッチＳ５を閉路して、第１閉路時間Ｔ１よりも短い所定時間ｔｄ１経過後、第５スイッチＳ５を開路つまり遮断した後、マイコン１１は、Ａ／Ｄポートを介してＡ／Ｄ変換データ、つまりコンデンサ９の両端子間の電圧ＶＣを読み込み、電圧ＶＣが０Ｖであることを確認する（ステップ２０９）。
【００２３】
電源電圧推定過程１０１終了後、図２に示すように、電源電圧異常判定１０３に進み、マイコン１１は、電源電圧推定過程１０１で推定した電源３の電源電圧Ｖ０ｓと予め入力された電源電圧の基準となる電源電圧基準範囲とを比較し、電源電圧推定過程１０１で推定した電源電圧Ｖ０ｓの値が電源電圧基準範囲から外れているとき、電源電圧の異常と判定する。ただし、絶縁検出装置１の構成及び絶縁抵抗の検出動作などからもわかるように、推定した電源電圧Ｖ０ｓは、スイッチ部に故障しているなどの異常が生じている場合にも異常な値を示す。そこで、電源電圧異常判定１０３において電源電圧の異常が判定された場合、電源電圧の異常またはスイッチ部の異常が生じていると判断されるため、異常の原因の判断、そしてスイッチ部に異常がある場合の異常があるスイッチの特定のため、各スイッチＳ１、Ｓ２、Ｓ３、Ｓ４の異常検出過程１０５〜１１１を行う。
【００２４】
第２スイッチ異常検出過程１０５では、図４に示すように、他のスイッチを遮断した状態で第１スイッチＳ１を例えば第１の設定時間である第１閉路時間Ｔ１の間、閉路する。このとき、第２スイッチＳ２に異常がなければ、電源３にコンデンサ９を直列に接続する回路は形成されず、コンデンサ９の両端子間の電圧ＶＣは上昇しない。第１閉路時間Ｔ１経過後、さらに第１閉路時間Ｔ１よりも短い所定時間ｔｗ１経過して第３スイッチＳ３及び第４スイッチＳ４を閉路する。つまり、第４のスイッチング手段により、コンデンサ９の両端子間の電圧を検出するマイコン１１が接続された回路を形成すると共に、第２抵抗Ｒ２、第３抵抗Ｒ３、そして第４抵抗Ｒ４を含むコンデンサ９からの放電回路を形成する。ここでマイコン１１がＡ／Ｄポートを介してコンデンサ９の両端子間の電圧ＶＣを読み込むと、コンデンサ９には充電が行われていないため、マイコン１１で電圧は検出されない。マイコン１１で電圧が検出されないことにより、異常検出手段であるマイコン１１は、第２スイッチＳ２に異常はないと判断する。
【００２５】
この後、図示していないスイッチング制御回路は、マイコン１１でコンデンサ９の両端子間の電圧ＶＣを検出した後、第３スイッチＳ３及び第４スイッチＳ４が閉路された状態で第５スイッチＳ５を閉路して第２抵抗Ｒ２をバイパスさせる。これにより、第２抵抗Ｒ２の抵抗値を下げた状態とし、コンデンサ９からの放電に要する時間を短縮する。第５スイッチＳ５を閉路して、第１閉路時間Ｔ１よりも短い所定時間ｔｄ１経過後、第５スイッチＳ５を開路つまり遮断した後、マイコン１１は、Ａ／Ｄポートを介してＡ／Ｄ変換データ、つまりコンデンサ９の両端子間の電圧ＶＣを読み込み、電圧ＶＣが０Ｖであることを確認し、第１スイッチ異常検出過程１０７へ進む。
【００２６】
一方、第２スイッチＳ２が故障などにより閉路状態または短絡状態になっているといった異常があると、電源３にコンデンサ９を直列に接続する回路が形成された状態となり、図５に示すように、第１閉路時間Ｔ１の間、コンデンサ９への充電が行われ、コンデンサ９の両端子間の電圧ＶＣが上昇する。したがって、スイッチＳ３及び第４スイッチＳ４を閉路し、マイコン１１がＡ／Ｄポートを介してコンデンサ９の両端子間の電圧ＶＣを読み込むと、第２スイッチＳ２の異常によりコンデンサ９への充電が行われたため、コンデンサ９の両端子間の電圧ＶＣに相当する電圧がマイコン１１で検出される。コンデンサ９の両端子間の電圧ＶＣに相当する電圧が検出されたことにより、異常検出手段であるマイコン１１は、第２スイッチＳ２が異常であると判断し、例えば絶縁抵抗値の計測を中止し、警報などにより異常を告知する。
【００２７】
第１スイッチ異常検出過程１０７では、図４に示すように、他のスイッチを遮断した状態で第２スイッチＳ２を例えば第１の設定時間である第１閉路時間Ｔ１の間、閉路する。このとき、第１スイッチＳ１に異常がなければ、電源３にコンデンサ９を直列に接続する回路は形成されず、コンデンサ９の両端子間の電圧ＶＣは上昇しない。第１閉路時間Ｔ１経過後、さらに第１閉路時間Ｔ１よりも短い所定時間ｔｗ１経過して第３スイッチＳ３及び第４スイッチＳ４を閉路する。つまり、第４のスイッチング手段により、コンデンサ９の両端子間の電圧を検出するマイコン１１が接続された回路を形成すると共に、第２抵抗Ｒ２、第３抵抗Ｒ３、そして第４抵抗Ｒ４を含むコンデンサ９からの放電回路を形成する。ここでマイコン１１がＡ／Ｄポートを介してコンデンサ９の両端子間の電圧ＶＣを読み込むと、コンデンサ９には充電が行われていないため、マイコン１１で電圧は検出されない。マイコン１１で電圧が検出されないことにより、異常検出手段であるマイコン１１は、第１スイッチＳ１に異常はないと判断する。
【００２８】
この後、図示していないスイッチング制御回路は、マイコン１１でコンデンサ９の両端子間の電圧ＶＣを検出した後、第３スイッチＳ３及び第４スイッチＳ４が閉路された状態で第５スイッチＳ５を閉路して第２抵抗Ｒ２をバイパスさせる。これにより、第２抵抗Ｒ２の抵抗値を下げた状態とし、コンデンサ９からの放電に要する時間を短縮する。第５スイッチＳ５を閉路して、第１閉路時間Ｔ１よりも短い所定時間ｔｄ１経過後、第５スイッチＳ５を開路つまり遮断した後、マイコン１１は、Ａ／Ｄポートを介してＡ／Ｄ変換データ、つまりコンデンサ９の両端子間の電圧ＶＣを読み込み、電圧ＶＣが０Ｖであることを確認し、第３スイッチ異常検出過程１０９へ進む。
【００２９】
一方、第１スイッチＳ１が故障などにより閉路状態または短絡状態になっているといった異常があると、電源３にコンデンサ９を直列に接続する回路が形成された状態となり、図６に示すように、第１閉路時間Ｔ１の間、コンデンサ９への充電が行われ、コンデンサ９の両端子間の電圧ＶＣが上昇する。したがって、スイッチＳ３及び第４スイッチＳ４を閉路し、マイコン１１がＡ／Ｄポートを介してコンデンサ９の両端子間の電圧ＶＣを読み込むと、第１スイッチＳ１の異常によりコンデンサ９への充電が行われたため、コンデンサ９の両端子間の電圧ＶＣに相当する電圧がマイコン１１で検出される。コンデンサ９の両端子間の電圧ＶＣに相当する電圧が検出されたことにより、異常検出手段であるマイコン１１は、第１スイッチＳ１が異常であると判断し、例えば絶縁抵抗値の計測を中止し、警報などにより異常を告知する。
【００３０】
第３スイッチ異常検出過程１０９及び第４スイッチ異常検出過程１１１は、本実施形態では一つの過程の中で行われる。第３スイッチ異常検出過程１０９及び第４スイッチ異常検出過程１１１では、図４に示すように、他のスイッチを遮断した状態で第１スイッチＳ１及び第２スイッチＳ２を例えば第１の設定時間である第１閉路時間Ｔ１の間、閉路する。つまり、第１スイッチング手段により、電源３にコンデンサ９を直列に接続する回路を形成し、第１閉路時間Ｔ１の間、コンデンサ９への充電を行う。これにより、コンデンサ９の両端子間の電圧ＶＣが上昇する。第１閉路時間Ｔ１経過後、さらに第１閉路時間Ｔ１よりも短い所定時間ｔｗ１経過して第３スイッチＳ３の異常を検出するため、第３スイッチＳ３を遮断した状態で第４スイッチＳ４を閉路する。
【００３１】
このとき、第３スイッチＳ３に異常がなければ、コンデンサ９の両端子間の電圧を検出するマイコン１１が接続された回路、そして、第２抵抗Ｒ２、第３抵抗Ｒ３、そして第４抵抗Ｒ４を含むコンデンサ９からの放電回路は形成されない。ここでマイコン１１がＡ／Ｄポートを介してコンデンサ９の両端子間の電圧ＶＣを読み込むと、マイコン１１のＡ／Ｄポートには電圧が印加されず、マイコン１１で電圧は検出されない。マイコン１１で電圧が検出されないことにより、異常検出手段であるマイコン１１は、第３スイッチＳ３に異常はないと判断する。
【００３２】
続いて、第３スイッチＳ３を閉路し、第３スイッチＳ３を閉路してから所定時間ｔｗ１経過した後、第４スイッチＳ４の異常を検出するため、第３スイッチＳ３を閉路した状態で第４スイッチＳ４を遮断する。このとき、第４スイッチＳ４に異常がなければ、コンデンサ９の両端子間の電圧を検出するマイコン１１が接続された回路、そして、第２抵抗Ｒ２、第３抵抗Ｒ３、そして第４抵抗Ｒ４を含むコンデンサ９からの放電回路は形成されない。ここでマイコン１１がＡ／Ｄポートを介してコンデンサ９の両端子間の電圧ＶＣを読み込むと、マイコン１１のＡ／Ｄポートには電圧が印加されず、マイコン１１で電圧は検出されない。マイコン１１で電圧が検出されないことにより、異常検出手段であるマイコン１１は、第４スイッチＳ４に異常はないと判断する。
【００３３】
この後、図示していないスイッチング制御回路は、マイコン１１のＡ／Ｄポートでの読み込みを行った後、第３スイッチＳ３及び第４スイッチＳ４が閉路された状態で第５スイッチＳ５を閉路して第２抵抗Ｒ２をバイパスさせる。これにより、第２抵抗Ｒ２の抵抗値を下げた状態とし、コンデンサ９からの放電に要する時間を短縮する。第５スイッチＳ５を閉路して、第１閉路時間Ｔ１よりも短い所定時間ｔｄ１経過後、第５スイッチＳ５を開路つまり遮断した後、マイコン１１は、Ａ／Ｄポートを介してＡ／Ｄ変換データ、つまりコンデンサ９の両端子間の電圧ＶＣを読み込み、電圧ＶＣが０Ｖであることを確認し、第３スイッチ異常検出過程１０９へ進む。絶縁抵抗計測過程１１３へ進む。
【００３４】
一方、第３スイッチＳ３が故障などにより閉路状態または短絡状態になっているといった異常があると、コンデンサ９の両端子間の電圧を検出するマイコン１１が接続された回路を形成した状態となると共に、第２抵抗Ｒ２、第３抵抗Ｒ３、そして第４抵抗Ｒ４を含むコンデンサ９からの放電回路を形成した状態となる。したがって、マイコン１１がＡ／Ｄポートを介してコンデンサ９の両端子間の電圧ＶＣを読み込むと、図７に示すように、第３スイッチＳ３の異常によりマイコン１１のＡ／Ｄポートにコンデンサ９の両端子間の電圧ＶＣが印加されるため、コンデンサ９の両端子間の電圧ＶＣに相当する電圧がマイコン１１で検出される。コンデンサ９の両端子間の電圧ＶＣに相当する電圧が検出されたことにより、異常検出手段であるマイコン１１は、第３スイッチＳ３が異常であると判断し、例えば絶縁抵抗値の計測を中止し、警報などにより異常を告知する。
【００３５】
また、第４スイッチＳ４が故障などにより閉路状態または短絡状態になっているといった異常があると、コンデンサ９の両端子間の電圧を検出するマイコン１１が接続された回路を形成した状態となると共に、第２抵抗Ｒ２、第３抵抗Ｒ３、そして第４抵抗Ｒ４を含むコンデンサ９からの放電回路を形成した状態となる。したがって、マイコン１１がＡ／Ｄポートを介してコンデンサ９の両端子間の電圧ＶＣを読み込むと、図８に示すように、第４スイッチＳ４の異常によりマイコン１１のＡ／Ｄポートにコンデンサ９の両端子間の電圧ＶＣが印加されるため、コンデンサ９の両端子間の電圧ＶＣに相当する電圧がマイコン１１で検出される。コンデンサ９の両端子間の電圧ＶＣに相当する電圧が検出されたことにより、異常検出手段であるマイコン１１は、第４スイッチＳ４が異常であると判断し、例えば絶縁抵抗値の計測を中止し、警報などにより異常を告知する。
【００３６】
なお、図７及び図８は、図４とは異なり、第３スイッチ異常検出過程１０９及び第４スイッチ異常検出過程１１１を個別に実施した場合の図を示しており、また、第３スイッチ異常検出過程１０９は、第３スイッチＳ３及び第４スイッチＳ４を同時に閉路した後、第３スイッチＳ３のみを遮断する方法を示している。
【００３７】
各スイッチスイッチ異常検出過程１０５、１０７、１０９、１１１でスイッチの異常が検出されなかった場合、つまり電源電圧自体の異常であることが検出された場合、または、図２及び図４に示すように、電源電圧異常判定１０３において電源電圧の異常が検出されなかった場合、絶縁抵抗計測過程１１３に進む。絶縁抵抗計測過程１１３では、図示していないスイッチング制御回路は、図４及び図９に示すように、第１スイッチＳ１及び第４スイッチＳ４を第２の設定時間である第２閉路時間Ｔ２の間、閉路する（ステップ３０１）。
【００３８】
すなわち、第２のスイッチング手段により、電源３の正端子と接地電位部７との間にコンデンサ９を直列に接続した回路、つまり、図１に示すように、正側主回路配線５ａ、第１スイッチＳ１、第１ダイオードＤ１、第１抵抗Ｒ１、コンデンサ９、第４スイッチＳ４、第４抵抗Ｒ４、接地電位部７、そして図１において点線で示すような位置に仮定される負端子側の地絡抵抗Ｒｎ、負側主回路配線５ｂを順次直列に電源３に接続した回路が形成される。これにより、第２閉路時間Ｔ２の間、コンデンサ９への充電が行われ、図４に示すように、地絡抵抗Ｒｎの値に応じてコンデンサ９の両端子間の電圧ＶＣが上昇する。なお、第２の設定時間である第２閉路時間Ｔ２も、第１閉路時間Ｔ１と同様に、コンデンサ９を完全に充電するのに必要な時間よりも短く、所定時間ｔｗ１、ｔｄ１よりも長い時間に設定されている。
【００３９】
ステップ３０１において第２閉路時間Ｔ２が経過すると、図４及び図９に示すように、第１スイッチＳ１が開路つまり遮断され、所定時間ｔｗ１経過後、第３スイッチＳ３が閉路され、第３スイッチＳ３及び第４スイッチＳ４が閉路された状態となる。すなわち、第４のスイッチング手段により、コンデンサ９の両端子間の電圧を検出するマイコン１１が接続された回路が形成されると共に、第２抵抗Ｒ２、第３抵抗Ｒ３、そして第４抵抗Ｒ４を含むコンデンサ９からの放電回路が形成され、コンデンサ９の両端子間の電圧ＶＣが降下する。そして、マイコン１１は、Ａ／Ｄポートを介してＡ／Ｄ変換データ、つまりコンデンサ９の両端子間の電圧ＶＣを読み込む（ステップ３０３）。このときのコンデンサ９の両端子間電圧ＶＣの値つまり検出電圧ＶＣＮにより、次式（２）から電源３の負端子側の接地電位部７となる車体などに対する絶縁抵抗、すなわち負端子側の地絡抵抗Ｒｎを算出する（ステップ３０５）。
Ｒｎ＝−Ｒ１−Ｔ２／Ｃ・ｌｎ（１−ＶＣＮ／Ｖ０ｓ） …（２）
ただし、式（２）において、Ｔ２は第１スイッチＳ１及び第４スイッチＳ４の閉路時間、Ｃはコンデンサ９の容量、Ｒ１は第１抵抗Ｒ１の抵抗値、電源電圧Ｖ０ｓは電源電圧推定過程１０１で推定した電源電圧である。
【００４０】
一方、図示していないスイッチング制御回路は、ステップ３０５でコンデンサ９の両端子間の電圧ＶＣを検出した後、第３スイッチＳ３及び第４スイッチＳ４が閉路された状態で、第５スイッチＳ５を閉路して第２抵抗Ｒ２をバイパスさせることで、第２抵抗Ｒ２の抵抗値を下げた状態とし、コンデンサ９からの放電に要する時間を短縮する。第５スイッチＳ５を閉路して、第２閉路時間Ｔ２よりも短い所定時間ｔｄ２経過後、第３スイッチＳ３、第４スイッチＳ４及び第５スイッチＳ５を開路つまり遮断した後、マイコン１１は、Ａ／Ｄポートを介してＡ／Ｄ変換データ、つまりコンデンサ９の両端子間の電圧ＶＣを読み込む（ステップ３０７）。
【００４１】
ステップ３０７で電圧ＶＣが０Ｖであることが確認されたら、図示していないスイッチング制御回路は、第２スイッチＳ２及び第３スイッチＳ３を第２の設定時間である第２閉路時間Ｔ２の間、閉路する（ステップ３０９）。すなわち、第３のスイッチング手段により、接地電位部７と電源３の負端子との間にコンデンサ９を直列に接続した回路、つまり、図１に示すように、正側主回路配線５ａ、図１において点線で示すような位置に仮定される正端子側の地絡抵抗Ｒｐ、接地電位部７、第３抵抗Ｒ３、第３スイッチＳ３、第１ダイオードＤ１、第１抵抗Ｒ１、コンデンサ９、第２スイッチＳ２、そして負側主回路配線５ｂを順次直列に電源３に接続した回路が形成される。これにより、第２閉路時間Ｔ２の間、コンデンサ９への充電が行われ、図４に示すように、地絡抵抗Ｒｐの値に応じてコンデンサ９の両端子間の電圧ＶＣが上昇する。
【００４２】
ステップ３０９において第２閉路時間Ｔ２が経過すると、図４及び図９に示すように、第２スイッチＳ２が開路つまり遮断され、所定時間ｔｗ１経過後、第４スイッチＳ４が閉路され、第３スイッチＳ３及び第４スイッチＳ４が閉路された状態となる。すなわち、第４のスイッチング手段により、コンデンサ９の両端子間の電圧を検出するマイコン１１が接続された回路が形成されると共に、第２抵抗Ｒ２、第３抵抗Ｒ３、そして第４抵抗Ｒ４を含むコンデンサ９からの放電回路が形成され、コンデンサ９の両端子間の電圧ＶＣが降下する。そして、マイコン１１は、Ａ／Ｄポートを介してＡ／Ｄ変換データ、つまりコンデンサ９の両端子間の電圧ＶＣを読み込む（ステップ３１１）。このときのコンデンサ９の両端子間電圧ＶＣの値つまり検出電圧ＶＣＰにより、次式（３）から電源３の正端子側の接地電位部７となる車体などに対する絶縁抵抗、すなわち正端子側の地絡抵抗Ｒｐを算出する（ステップ３１３）。
Ｒｐ＝−Ｒ１−Ｔ２／Ｃ・ｌｎ（１−ＶＣＰ／Ｖ０ｓ） …（３）
ただし、式（３）において、Ｔ２は第２スイッチＳ２及び第３スイッチＳ３の閉路時間、Ｃはコンデンサ９の容量、Ｒ１は第１抵抗Ｒ１の抵抗値、電源電圧Ｖ０ｓは電源電圧推定過程１０１で推定した電源電圧である。
【００４３】
一方、図示していないスイッチング制御回路は、ステップ３１３でコンデンサ９の両端子間の電圧ＶＣを検出した後、第３スイッチＳ３及び第４スイッチＳ４が閉路された状態で、第５スイッチＳ５を閉路して第２抵抗Ｒ２をバイパスさせることで、第２抵抗Ｒ２の抵抗値を下げた状態とし、コンデンサ９からの放電に要する時間を短縮する。第５スイッチＳ５を閉路して所定時間ｔｄ２経過後、第３スイッチＳ３、第４スイッチＳ４及び第５スイッチＳ５を開路つまり遮断した後、マイコン１１は、Ａ／Ｄポートを介してＡ／Ｄ変換データ、つまりコンデンサ９の両端子間の電圧ＶＣを読み込む（ステップ３１５）。そして、ステップ３１５で電圧ＶＣが０Ｖであることが確認された時点で、１回の絶縁状態の検出サイクルを終了する。また、絶縁状態の検出を行う間、図２、図３及び図９に示す、絶縁抵抗の計測過程１０１からステップ１１３までの検出サイクルを繰り返す。
【００４４】
マイコン１１は、１回の絶縁状態の検出サイクルで求めた電源３の正端子側の地絡抵抗Ｒｐと、負端子側の地絡抵抗Ｒｎの値から絶縁状態を判定する。例えば、電源３の正端子側の地絡抵抗Ｒｐと、予め定められた基準抵抗値とを比較し、地絡抵抗Ｒｐが基準抵抗値以下になっている場合には、絶縁不良が生じていると判定する。
【００４５】
ところで、式（２）、（３）などからわかるように、コンデンサ９の容量Ｃ、さらに第１抵抗Ｒ１の抵抗値Ｒ１が製品間差や温度変化などによりばらつくと、電源３の正端子側の地絡抵抗Ｒｐ、負端子側の地絡抵抗Ｒｎの計測精度に影響し、検出した地絡抵抗Ｒｐ、Ｒｎの値の精度が低下してしまう。したがって、絶縁状態の検出精度が低下してしまうことになる。特にコンデンサ９は、浮遊容量を考慮すると数μＦといった比較的大きな値のものが必要となるため、例えば製品間差において±５％程度のばらつきがあるとすると、これに温度変化を考慮すると±１０％程度のばらつきが生じる場合があり、このようなコンデンサ９の容量のばらつきが絶縁状態の検出精度を低下させてしまうことになる。加えて、経時変化による部品定数の変化によって生じるばらつきなども絶縁状態の検出精度を低下させてしまうことになる。
【００４６】
これに対して本実施形態の絶縁検出装置１では、絶縁検出のサイクルの最初の段階で第１スイッチＳ１と第２スイッチＳ２を、コンデンサ９を完全に充電するのに要する時間よりも短い第１閉路時間Ｔ１の間閉路することにより、電源３の電源電圧を推定している。第１スイッチＳ１と第２スイッチＳ２を短時間閉路してコンデンサ９を充電する場合は、実際のコンデンサ９の容量と抵抗Ｒ１の抵抗値とで決定される時定数Ｃ・Ｒ１で充電されるときの充電到達電圧を推定する方式であるため、推定した電源電圧Ｖ０ｓは、実際の電源３の電源電圧ではなく、コンデンサ９と抵抗Ｒ１の容量及び抵抗値の誤差、つまりばらつきを含んだ値となる。そして、このばらつきを含む推定した電源電圧Ｖ０ｓを、絶縁検出のサイクルにおける以降に続くステップで行う正端子側の地絡抵抗Ｒｐ、負端子側の地絡抵抗Ｒｎの演算に用いることで、コンデンサ９の容量のばらつきに対する補正が行われ、コンデンサ９の容量のばらつきによって生じる実際の正端子側地絡抵抗Ｒｐ及び負端子側地絡抵抗Ｒｎの値と、算出した正端子側地絡抵抗Ｒｐ及び負端子側地絡抵抗Ｒｎの値との誤差を低減することができる。したがって、絶縁状態の検出精度を向上できる。
【００４７】
このような本実施形態の絶縁検出装置１によって計測した正端子側の地絡抵抗Ｒｐ及び負端子側の地絡抵抗Ｒｎの値と、実際の正端子側の地絡抵抗Ｒｐ及び負端子側の地絡抵抗Ｒｎの値との誤差をある所定の規格容量を有するコンデンサ９、そしてある所定の規格抵抗値を有する第１抵抗Ｒ１を用いた場合を想定して計算した結果を図１０に示す。なお、コンデンサ９は、製品間差と温度変化を考慮して±１０％程度の容量のばらつきが、第１抵抗Ｒ１は、製品間差と温度変化を考慮して±２％程度の容量のばらつきがあるものとする。図１０において、Ｖ０計測時間は、第１閉路時間を意味し、したがって、図４では、第１閉路時間Ｔ１をｔ秒、２ｔ秒、そして３ｔ秒、ただしｔ＜２ｔ＜３ｔとした場合の計測誤差を示している。なお、図１０は、縦軸を検出精度つまり検出誤差、横軸を地絡抵抗の値として計算結果をグラフ化したものである。
【００４８】
図１０からわかるように、従来の絶縁検出装置で検出した場合、つまり補正無しの場合に比べて、本実施形態の絶縁検出装置１で検出した場合、つまり補正ありの場合の方が各地絡抵抗値に対して計測誤差が低減されている。さらに、Ｖ０計測時間つまり第１閉路時間Ｔ１の設定によって計測誤差の低減度合いが異なっており、第１閉路時間Ｔ１がｔ秒のときには、地絡抵抗が小さくなるにしたがって誤差が大きくなるが、地絡抵抗が大きくなるにしたがって誤差が小さくなっている。第１閉路時間Ｔ１が２ｔ秒のときには、地絡抵抗が大きい場合には、第１閉路時間Ｔ１がｔ秒のときよりも誤差が大きくなるが、各地絡抵抗にわたって平均的に誤差が小さくなっている。第１閉路時間Ｔ１が３ｔ秒のときにも各地絡抵抗にわたって平均的に誤差が小さくなっているが、誤差は、第１閉路時間Ｔ１が２ｔ秒のときよりも大きい。
【００４９】
したがって、絶縁不良を判定する地絡抵抗の値の設定を比較的大きな値とする場合には、第１閉路時間Ｔ１をｔ秒とするのが好ましく、絶縁不良を判定する地絡抵抗の値の設定を比較的小さな値とする場合には、第１閉路時間Ｔ１を２ｔ秒とするのが好ましい。このように、第１閉路時間Ｔ１つまり第１の設定時間は、絶縁不良を判定する地絡抵抗の値周辺で計測誤差が小さくなるように選択するのが好ましい。例えば、図１０において絶縁不良を判定する地絡抵抗の値をＲΩに設定したとすれば、第１閉路時間Ｔ１として２ｔ秒を選択するのが好ましく、このとき、従来の絶縁検出装置では±１０％以上の計測誤差があるのに対し、本実施形態の絶縁検出装置１では、±２％以下の計測誤差となり、絶縁状態の検出精度を向上できることになる。
【００５０】
このように、本実施形態の絶縁検出装置１では、異常検出手段となるマイコン１１が、第１、第２、第３及び第４の各スイッチング手段を構成しているスイッチ部である第１、第２、第３及び第４の各スイッチＳ１、Ｓ２、Ｓ３、Ｓ４を個別に検査して異常を判定するため、異常が発生したスイッチを特定できる。
【００５１】
また、本実施形態では、第１スイッチ異常検出過程１０７、第２スイッチ異常検出過程１０５、第３スイッチ異常検出過程１０９及び第４スイッチ異常検出過程１１１を電源電圧推定過程１０１の後に行っているが、各スイッチ異常検出過程１０５、１０７、１０９、１１１は、絶縁抵抗の計測過程のどこで行ってもよい。さらに、第１スイッチ異常検出過程１０７、第２スイッチ異常検出過程１０５、第３スイッチ異常検出過程１０９及び第４スイッチ異常検出過程１１１を行う順番も、適宜入れ替えることができる。
【００５２】
ただし、本実施形態のように、まず電源電圧推定過程１０１を行って電源電圧異常判定１０３を行った後に、その結果に応じて各スイッチ異常検出過程１０５、１０７、１０９、１１１を行えば、無駄な異常検出動作を行うことなく効率よく異常検出を行え、また、絶縁抵抗の計測時間を短縮できる。加えて、第３スイッチ異常検出過程１０９及び第４スイッチ異常検出過程１１１の結果は、第１スイッチＳ１及び第２スイッチＳ２の状態に影響されるため、第１スイッチ異常検出過程１０７及び第２スイッチ異常検出過程１０５を行った後、第３スイッチ異常検出過程１０９及び第４スイッチ異常検出過程１１１を行うことが望ましい。このとき、第１スイッチ異常検出過程１０７及び第２スイッチ異常検出過程１０５の順番、第３スイッチ異常検出過程１０９及び第４スイッチ異常検出過程１１１の順番は、適宜入れ替えることができる。
【００５３】
また、本実施形態では、正端子側の地絡抵抗Ｒｐと負端子側の地絡抵抗Ｒｎを個別に算出し、これにより絶縁不良の部位も検出できるようにしている。しかし、絶縁不良の部位を検出せず絶縁不良の発生のみを判定する場合などには、推定した電源電圧Ｖ０ｓと検出電圧ＶＣＰ、ＶＣＮなどとに基づいて正端子側の地絡抵抗Ｒｐと負端子側の地絡抵抗Ｒｎとを代表する地絡抵抗値などを算出する別の式を用いることもできる。
【００５４】
また、本実施形態の絶縁検出装置１では、演算手段となるマイコン１１によって式（１）や式（２）、（３）によって推定した電源電圧Ｖ０ｓや地絡抵抗値Ｒｎ、Ｒｐを演算している。しかし、これらの式（１）や式（２）、（３）といった複雑な関数式の演算にかかる時間を短縮するため、マイコン１１の記憶手段となるメモリなどにアドレスに対応させて推定した電源電圧Ｖ０ｓや地絡抵抗値Ｒｎ、Ｒｐなどを記憶した電源電圧用データテーブルや地絡抵抗値用データテーブルなどを準備し、演算手段であるマイコン１１で各々のデータテーブルに対応したアドレスを演算する構成にすることもできる。このとき、演算手段であるマイコン１１は、電源電圧を推定するために検出したコンデンサ９の両端子間電圧ＶＣの値つまり検出電圧Ｖ０、推定した電源電圧Ｖ０ｓ及び地絡抵抗値Ｒｎ、Ｒｐを求めるために検出したコンデンサ９の両端子間電圧ＶＣの値つまり検出電圧ＶＣＮ、ＶＣＰなどから、式（１）や式（２）、（３）よりも簡単なアドレスの演算式により、各々電源電圧用データテーブルのアドレス、地絡抵抗値用データテーブルのアドレスを算出し、この算出した各々のアドレスから推定した電源電圧Ｖ０ｓや地絡抵抗値Ｒｎ、Ｒｐを決定する。
【００５５】
また、第５スイッチＳ５を含むバイパス手段としては、本実施形態の構成に限らず、バイパス手段は、図１１に示すように、第２抵抗Ｒ２の両端子間に、第２抵抗Ｒ２と並列に第５スイッチＳ５が接続されている構成にすることもできる。また、絶縁検出のための１サイクルに要する時間の短縮などの必要性がない場合などには、第５スイッチＳ５を含むバイパス手段を設けない構成にすることもできる。
【００５６】
また、本発明は、本実施形態において示した回路構成に限らず、正端子側及び負端子側の配線が接地電位部から絶縁された直流電源にコンデンサを直列に第１の設定時間の間接続する第１のスイッチング手段、電源の正端子と接地電位部との間に前記コンデンサを直列に第２の設定時間の間接続する第２のスイッチング手段、電源の負端子と接地電位部との間にコンデンサを直列に第２の設定時間の間接続する第３のスイッチング手段、第１、第２及び第３の各スイッチング手段の遮断後にコンデンサの両端子間の電圧を検出する検出手段を接続する第４のスイッチング手段などをそなえていれば様々な回路構成の絶縁検出装置に適用することができる。
【００５７】
【発明の効果】
本発明によれば、異常が発生したスイッチを特定できる。
【図面の簡単な説明】
【図１】本発明を適用してなる絶縁検出装置の一実施形態の概略構成を示す図である。
【図２】本発明を適用してなる絶縁検出装置の一実施形態の絶縁抵抗計測の動作を示すフロー図である。
【図３】本発明を適用してなる絶縁検出装置の一実施形態の電源電圧推定過程の動作を示すフロー図である。
【図４】電源電圧正常時及び異常時の各スイッチ部の動作に対するコンデンサの充放電状態と電圧の読み込みタイミングを示すタイムチャートである。
【図５】第２スイッチの異常検出過程の各スイッチ部の動作に対するコンデンサの充放電状態と電圧の読み込みタイミングを示すタイムチャートである。
【図６】第１スイッチの異常検出過程の各スイッチ部の動作に対するコンデンサの充放電状態と電圧の読み込みタイミングを示すタイムチャートである。
【図７】第３スイッチの異常検出過程の各スイッチ部の動作に対するコンデンサの充放電状態と電圧の読み込みタイミングを示すタイムチャートである。
【図８】第４スイッチの異常検出過程の各スイッチ部の動作に対するコンデンサの充放電状態と電圧の読み込みタイミングを示すタイムチャートである。
【図９】本発明を適用してなる絶縁検出装置の一実施形態の絶縁抵抗計測過程の動作を示すフロー図である。
【図１０】絶縁抵抗の値に対する各電源電圧の計測時間で検出した絶縁抵抗の値の検出誤差を示す図である。
【図１１】本発明を適用してなる絶縁検出装置の変形例の概略構成を示す図である。
【符号の説明】
１ 絶縁検出装置
３ 電源
５ａ 正側主回路配線
５ｂ 負側主回路配線
７ 接地電位部
９ コンデンサ
１１ マイコン
Ｓ１ 第１スイッチ
Ｓ２ 第２スイッチ
Ｓ３ 第３スイッチ
Ｓ４ 第４スイッチ
Ｒｐ 正端子側地絡抵抗
Ｒｎ 負端子側地絡抵抗[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an insulation detection device for an ungrounded power supply, and more particularly to an insulation detection device suitable for an ungrounded DC power supply mounted on a vehicle that uses electric propulsion.
[0002]
[Prior art]
The insulation detection device of the ungrounded power supply is connected to the positive and negative terminals of the ungrounded DC power supply, and is insulated from the ground potential part by the insulation resistance to the ground potential part of the main circuit wiring on the positive and negative sides, that is, the ground fault resistance. Is detected to detect insulation with respect to the ground potential portion and a ground fault state (for example, see Patent Document 1). In such a conventional insulation detection device, switching means for connecting a capacitor in series between a positive terminal of an ungrounded DC power supply and a ground potential section for a set time, a negative terminal of an ungrounded power supply and a ground potential section A switching means for connecting a capacitor in series for a set time, a switching means for detection connecting a detection means for detecting a voltage between both terminals of the capacitor after each switching means is cut off, Calculation means for obtaining an insulation resistance to a ground potential portion of a power supply, that is, a ground fault resistance, based on a voltage between both terminals of the capacitor after the switching means is cut off and a power supply voltage previously calculated by fully charging the capacitor. And detects and determines the insulation state from the ground fault resistance obtained by the calculation means.
[0003]
In such an insulation detection device, when obtaining the ground fault resistance, an expression including the capacitance of the capacitor as a constant is used. However, the capacitance of the capacitor used as the constant includes a capacitance due to variation in capacitance between products and a temperature change. In some cases, and there is also a case where a change over time in the capacity or the like occurs. If the values used as constants vary or change in this way, the measurement error between the obtained ground fault resistance value and the actual ground fault resistance value increases, and the insulation state detection accuracy decreases. I will. Therefore, it is desirable to reduce the measurement error of the ground fault resistance as much as possible and to improve the detection accuracy of the insulation state, even if there are variations or changes in the values used as constants for obtaining the ground fault resistance such as the capacitance of the capacitor. ing.
[0004]
Therefore, the inventors of the present application provide first switching means for connecting a capacitor in series for a first set time to a DC power supply in which the wiring on the positive terminal side and the wiring on the negative terminal side are insulated from the ground potential portion; Second switching means for connecting a capacitor in series between the positive terminal and the ground potential for a second set time, and second setting in series for a capacitor between the negative terminal of the power supply and the ground potential A third switching means connected for a time, a fourth switching means connected to a voltage detecting means for detecting a voltage between both terminals of the capacitor after the first, second and third switching means are cut off; The power supply voltage of the power supply is estimated based on the voltage detected by the voltage detection means after the first switching means has been cut off, and the estimated power supply voltage and each of the voltages detected by the detection means after the second and third switching means have been cut off. Detection voltage Contemplates insulation detecting device of the configuration and an arithmetic means for obtaining the insulation resistance to ground potential of the power based on.
[0005]
With the insulation detection device having such a configuration, the DC power supply and the ground potential unit are connected by the first switching means for a first set time set in a time shorter than the time required for completely charging the capacitor. During this time, the capacitor is connected to DC and charged. At this time, the voltage between both terminals of the capacitor is detected by the detecting means connected by the fourth switching means, and the calculating means estimates the power supply voltage from the detected voltage, and this power supply voltage is compared with the second and third power supply voltages. By obtaining the insulation resistance with respect to the ground potential portion based on the detection voltage of the detection means after the switching means is cut off, the measurement error of the insulation resistance can be reduced and the detection accuracy of the insulation state can be improved.
[0006]
By the way, in such an insulation detecting device, if an abnormality occurs in each switching means, an erroneous ground fault resistance value is obtained. I don't know if it was due to an abnormality in the means. For this reason, the inventors of the present application need to detect the abnormality of the switching means in the process of detecting the insulation state before connecting the capacitors in series to the power supply by the first switching means. And from the state in which the fourth switching means is cut off, to the time in which the voltage detection means is connected by the fourth switching means after the cut-off of the first switching means and before the fourth switching means is cut off. It is considered that the configuration includes an abnormality detection unit that detects abnormality of the first, second, third, and fourth switching units based on the detected detection voltage.
[0007]
At this time, the first, second, third, and fourth switching means are turned off before the capacitor is connected in series to the power supply by the first switching means, and the fourth switching means is turned off after the first switching means is turned off. After the voltage detecting means is connected by the switching means, until the fourth switching means is shut off, that is, the detection voltage obtained by the detecting means in the process of estimating the power supply voltage of the power supply affects the insulation state, that is, the ground fault resistance. It is not a value. For this reason, by providing a configuration including an abnormality detection unit that detects an abnormality based on the detection voltage of the detection unit in the process of estimating the power supply voltage of the power supply as described above, the abnormality of the switching unit is measured in the insulation state measurement process. Can be detected.
[Patent Document 1]
JP-A-8-226950 (page 4-7, FIG. 1)
[0008]
[Problems to be solved by the invention]
However, in the insulation detection device including the above-described abnormality detection unit, when each switching unit has a circuit configuration including two switch units, that is, the first switching unit is connected to the positive terminal of the power supply. A first switch unit; and a second switch unit connected to a negative terminal of the power supply, wherein the third switching unit is connected to the second switch unit and a third switch connected in series to the first switch. The second switching means includes a first switch section and a fourth switch section connected in series to the second switch section, and the fourth switching means includes a third switch section. From the positive side, between the first switch unit and the third switch unit, and between the second switch unit S2 and the fourth switch unit. First damper rectifying in the direction toward the negative side A diode, a first resistor and a capacitor are connected in series, and a second diode and a second resistor, which are rectified in the opposite direction to the first diode, are connected in series with the first diode and the first resistor. If the detection means is connected between the third switch part and the fourth switch part and the circuit between the detection means and the fourth switch part is grounded to the ground potential part, Since the detecting means detects the abnormality by combining the two switch units, that is, the switches, it is possible to identify the switching means or the combination of the two switches in which the abnormality has occurred, but which of the two switches has the abnormality It cannot be specified.
[0009]
As described above, when each switching unit has a circuit configuration including two switch units, that is, switches, the abnormality detection unit of the insulation detection device, which has been conventionally considered, cannot identify the switch in which the abnormality has occurred. There is a case where a problem that a response cannot be taken promptly occurs. For this reason, it is an issue to specify a switch in which an abnormality has occurred.
[0010]
An object of the present invention is to specify a switch in which an abnormality has occurred.
[0011]
[Means for Solving the Problems]
The insulation detection device of the present invention includes a capacitor connected in series to a DC power supply in which the wiring on the positive terminal side and the wiring on the negative terminal side are insulated from the ground potential, and a first set time shorter than the time required for the capacitor to be completely charged. A second switching means for connecting a capacitor in series between a positive terminal of the power supply and a ground potential section for a second set time; a negative terminal of the power supply and a ground potential A third switching means for connecting a capacitor in series with the first switching means for a second set time, and detecting a voltage between both terminals of the capacitor after the first, second and third switching means are cut off. The power supply voltage of the power supply is estimated based on the voltage detected by the fourth switching means for connecting the voltage detection means and the voltage detection means after the first switching means is cut off. Three Calculating means for determining an insulation resistance of the power supply with respect to the ground potential portion based on the respective detected voltages of the voltage detecting means after the switching means has been cut off, and an abnormality occurring in the first, second, third and fourth switching means. The first switching means includes a first switch section connected to the positive terminal of the power supply, and a second switch section connected to the negative terminal of the power supply. The third switching means includes a second switch section and a third switch section connected in series to the first switch, and the second switching means includes a first switch section and a second switch section. And a fourth switch unit connected in series to the unit, wherein the fourth switching means includes a third switch unit and a fourth switch unit, and the first switch unit and the third switch unit. Between the second switch unit and the second A first diode and a capacitor, which rectify in the direction from the positive side to the negative side, are connected in series with the switch unit, and the rectification is performed in parallel with the first diode and in the opposite direction to the first diode. The second diode is connected, the voltage detection means is connected between the third switch section and the fourth switch section, and the voltage detection means and the fourth switch section are grounded to the ground potential section. The abnormality detecting means closes only the second switch for a third set time, and then detects the first switch based on a voltage detected by the voltage detecting when the fourth switching is closed. Is determined, and only the first switch unit is closed for the fourth set time, and then the second switch unit is closed based on the voltage detected by the voltage detection unit when the fourth switching unit is closed. Determine the abnormality and perform the first switching After the means is closed for a fifth set time, the third switch is shut off and the third switch is determined to be abnormal based on the voltage detected by the voltage detecting means when the fourth switch is closed. After the first switching means is closed for the sixth set time, the fourth switch is closed based on the voltage detected by the voltage detection means when the third switch is closed and the fourth switch is shut off. The above problem is solved by adopting a configuration for detecting an abnormality of the switch section.
[0012]
With such a configuration, the abnormality detection unit can switch the first, second, third, and fourth switch units constituting the first, second, third, and fourth switching units. Since the inspection is performed individually to determine the abnormality, the switch in which the abnormality has occurred can be specified.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an insulation detection device to which the present invention is applied will be described with reference to FIGS. FIG. 1 is a diagram showing a schematic configuration of an insulation detection device to which the present invention is applied. FIG. 2 is a flowchart showing an insulation resistance measuring operation of the insulation detection device to which the present invention is applied. FIG. 3 is a flowchart showing the operation of the power supply voltage estimation process in the insulation resistance measurement process of the insulation detection device according to the present invention. FIG. 4 is a time chart showing the charging / discharging state of the capacitor and the voltage reading timing with respect to the operation of each switch unit when the power supply voltage is normal and abnormal. FIG. 5 is a time chart showing the charging / discharging state of the capacitor and the voltage reading timing with respect to the operation of each switch unit in the process of detecting the abnormality of the second switch. FIG. 6 is a time chart showing the charging / discharging state of the capacitor and the voltage reading timing with respect to the operation of each switch unit in the process of detecting the abnormality of the first switch. FIG. 7 is a time chart showing the charging / discharging state of the capacitor and the voltage reading timing with respect to the operation of each switch unit in the abnormality detection process of the third switch. FIG. 8 is a time chart showing the charging / discharging state of the capacitor and the voltage reading timing with respect to the operation of each switch unit in the process of detecting the abnormality of the fourth switch. FIG. 9 is a flowchart showing the operation of the insulation resistance measuring process of the insulation detection device to which the present invention is applied. FIG. 10 is a diagram illustrating a detection error of the insulation resistance value detected during the measurement time of each power supply voltage with respect to the insulation resistance value. In the time chart of FIG. 4, the detection voltage VC and the A / D conversion value in the switch abnormality detection process show a state where there is no abnormality in the switch. In the time charts of FIGS. The detected voltage VC and the A / D conversion value indicate the state when the switch is abnormal.
[0014]
As shown in FIG. 1, the insulation detection device 1 of the present embodiment is applied to a DC power supply 3 serving as a power source of, for example, an electric propulsion vehicle that obtains propulsion using electric power. The power supply 3 is formed by connecting a plurality of storage batteries and the like in series. The positive main circuit wiring 5a on the positive terminal side and the negative main circuit wiring 5b on the negative terminal side of the power supply 3 are each connected to the ground potential unit 7, for example. The power supply 3 is insulated from the vehicle body and the like, and is a non-grounded power supply. The insulation detection device 1 includes a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a capacitor 9, a microcomputer 11 which also serves as a voltage detection unit and a calculation unit and determines an insulation state, and each switch. It is composed of a switching control circuit (not shown) that controls opening and closing according to the set time.
[0015]
Note that the microcomputer 11 of the present embodiment also functions as an abnormality detection unit that detects an abnormality of each switch such as the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4. Further, the voltage detection means, the calculation means, the abnormality detection means, the switching control circuit, and the like can be separately formed or integrally formed, for example, by including a switching control circuit (not shown) in the microcomputer 11 integrally. Further, the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 shown in FIG. 1 are typically formed by using, for example, a switch unit composed of components having various switch functions such as a relay and a semiconductor switch as a contact. This is shown in FIG.
[0016]
A first switch S1 and a third switch S3 are sequentially connected in series to the positive terminal of the power supply 3 from the positive terminal, and a second switch S2 and a second switch S2 are connected to the negative terminal of the power supply 3 from the negative terminal. The four switches S4 and the fourth resistor R4 are sequentially connected in series. A first diode D1, a first resistor R1, and a capacitor 9 are sequentially connected in series between the first switch S1 and the third switch S3 and between the second switch S2 and the fourth switch S4. A second diode D2 and a second resistor R2 are sequentially connected in series between the first resistor R1 and the capacitor 9 and between the first switch S1 and the third switch S3. That is, the first diode D1 and the first resistor R1, and the second diode D2 and the second resistor R2 are connected in parallel. As a bypass means, a fifth switch S5 and a fifth resistor R5 having a lower resistance than the second resistor R2 are sequentially connected in series from a portion between the second diode D2 and the second resistor R2 to the ground potential section 7. It is connected. The first diode D1 rectifies in the direction from the positive side to the negative side, and the second diode D2 rectifies in the direction opposite to the first diode D1.
[0017]
A third resistor R3 is connected between the third switch S3 and the fourth resistor R4 in series with the third switch S3 and the fourth resistor R4, and is connected between the third switch S3 and the third resistor R3. Is connected to the microcomputer 11 via an analog / digital conversion port of the microcomputer 11, that is, an A / D port. Further, a portion between the third resistor R3 and the fourth resistor R4 is grounded to the ground potential section 7.
[0018]
Accordingly, the first switching means for connecting the capacitor 9 in series with the power supply 3 for the first set time is a first switch S1, a second switch S2, a switching control circuit (not shown), and the like. A second switching means for connecting a capacitor 9 in series between the terminal and the ground potential unit 7 for a second set time includes a first switch S1, a fourth switch S4, a switching control circuit (not shown), and the like. The third switching means for connecting a capacitor 9 in series between the ground potential unit 7 and the negative terminal of the power supply 3 for a second set time includes a second switch S2, a third switch S3, and not shown. In a switching control circuit or the like, the fourth switching means is formed by a third switch S3, a fourth switch S4, a switching control circuit (not shown), and the like. The capacitor 9 has a relatively high capacitance of, for example, several μF, and the first resistor R1 and the second resistor R2 have a relatively high resistance of, for example, several hundred kΩ. .
[0019]
The operation of the insulation detecting device having such a configuration and the features of the present invention will be described. As shown in FIG. 2, the insulation detection by the insulation detection device 1 of the present embodiment is performed by a power supply voltage estimation process 101 for estimating the power supply voltage of the power supply 3, and a power supply voltage estimated by the power supply voltage estimation 101. A power supply voltage abnormality determination 103 for detecting voltage abnormality, and a second switch for detecting abnormality of each of the switches S2, S1, S3, S4 performed when the power supply voltage is determined to be abnormal in the power supply voltage abnormality determination 103 An abnormality detection step 105, a first switch abnormality detection step 107, a third switch abnormality detection step 109, a fourth switch abnormality detection step 111, and an insulation resistance measurement step 113 are performed.
[0020]
In the power supply voltage estimation step 101, as shown in FIGS. 3 and 4, when the power supply voltage estimation step 101 is started, a switching control circuit (not shown) switches the first switch S1 and the second switch S2 for a first set time. The circuit is closed for a certain first closing time T1 (step 201). That is, the first switching means forms a circuit for connecting the capacitor 9 in series to the power supply 3 without passing through the ground potential unit 7, and the capacitor 9 is charged during the first closed time T1, and the capacitor 9 is charged. 9, the voltage VC between both terminals increases. The first closing time T1 is set to a time shorter than the time required to completely charge the capacitor 9, and is, for example, 1/5 to 1 to 1 times the time required to completely charge the capacitor 9. / 10, and the first closing time T1 is selected according to the required measurement error range of the insulation resistance.
[0021]
In step 201, when the first closing time T1 elapses, the first switch S1 and the second switch S2 are opened or cut off, and after the lapse of a predetermined time tw1 shorter than the first closing time T1, the third switch S3 and the fourth switch S4. Is closed (step 203). That is, the fourth switching means forms a circuit to which the microcomputer 11 for detecting the voltage between both terminals of the capacitor 9 is connected, and includes the second resistor R2, the third resistor R3, and the fourth resistor R4. A discharge circuit from the capacitor 9 is formed, and the voltage VC between both terminals of the capacitor 9 drops. Here, the microcomputer 11 reads the A / D conversion data via the A / D port, that is, the voltage VC between both terminals of the capacitor 9 (Step 205). Based on the value of the voltage VC between both terminals of the capacitor 9 at this time, that is, the detected voltage V0, the estimated power supply voltage V0s is calculated from the following equation (1) (step 207).
V0s = V0 / (1−EXP (−T1 / C · R1)) (1)
In the equation (1), T1 is the closing time of the first switch S1 and the second switch S2, C is the capacitance of the capacitor 9, and R1 is the resistance value of the first resistor R1.
[0022]
On the other hand, the switching control circuit (not shown) detects the voltage VC between both terminals of the capacitor 9 in step 205 and then closes the fifth switch S5 with the third switch S3 and the fourth switch S4 closed. By bypassing the second resistor R2, the resistance value of the second resistor R2 is reduced, and the time required for discharging from the capacitor 9 is reduced. After the fifth switch S5 is closed and a predetermined time td1 shorter than the first closed time T1 has elapsed, the fifth switch S5 is opened or shut off, and then the microcomputer 11 outputs the A / D converted data via the A / D port. That is, the voltage VC between both terminals of the capacitor 9 is read, and it is confirmed that the voltage VC is 0 V (step 209).
[0023]
After the power supply voltage estimation process 101 is completed, the process proceeds to the power supply voltage abnormality determination 103 as shown in FIG. 2, and the microcomputer 11 determines the power supply voltage V0s of the power supply 3 estimated in the power supply voltage estimation process 101 and the reference of the power supply voltage input in advance. Is compared with the power supply voltage reference range, and when the value of the power supply voltage V0s estimated in the power supply voltage estimation step 101 is out of the power supply voltage reference range, it is determined that the power supply voltage is abnormal. However, as can be seen from the configuration of the insulation detection device 1 and the operation of detecting the insulation resistance, the estimated power supply voltage V0s indicates an abnormal value even when an abnormality such as a failure of the switch unit occurs. . Therefore, if the power supply voltage abnormality is determined in the power supply voltage abnormality determination 103, it is determined that the power supply voltage is abnormal or the switch unit is abnormal. Therefore, the cause of the abnormality is determined, and the switch unit is abnormal. In order to identify a switch having an abnormality in the case, abnormality detection steps 105 to 111 of the switches S1, S2, S3, and S4 are performed.
[0024]
In the second switch abnormality detection step 105, as shown in FIG. 4, the first switch S1 is closed for a first closing time T1, for example, a first set time while the other switches are shut off. At this time, if there is no abnormality in the second switch S2, a circuit for connecting the capacitor 9 in series to the power supply 3 is not formed, and the voltage VC between both terminals of the capacitor 9 does not increase. After the lapse of the first closing time T1, the third switch S3 and the fourth switch S4 are closed after a lapse of a predetermined time tw1 shorter than the first closing time T1. That is, the fourth switching means forms a circuit to which the microcomputer 11 for detecting the voltage between both terminals of the capacitor 9 is connected, and the capacitor including the second resistor R2, the third resistor R3, and the fourth resistor R4. 9 to form a discharge circuit. Here, when the microcomputer 11 reads the voltage VC between both terminals of the capacitor 9 via the A / D port, the voltage is not detected by the microcomputer 11 because the capacitor 9 is not charged. Since the voltage is not detected by the microcomputer 11, the microcomputer 11 as the abnormality detecting means determines that the second switch S2 has no abnormality.
[0025]
Thereafter, the switching control circuit (not shown) closes the fifth switch S5 with the third switch S3 and the fourth switch S4 closed after the microcomputer 11 detects the voltage VC between both terminals of the capacitor 9 by the microcomputer 11. To bypass the second resistor R2. As a result, the resistance value of the second resistor R2 is reduced, and the time required for discharging from the capacitor 9 is reduced. After the fifth switch S5 is closed and a predetermined time td1 shorter than the first closed time T1 has elapsed, the fifth switch S5 is opened or shut off, and then the microcomputer 11 outputs the A / D converted data via the A / D port. That is, the voltage VC between both terminals of the capacitor 9 is read, and it is confirmed that the voltage VC is 0 V. Then, the process proceeds to the first switch abnormality detecting step 107.
[0026]
On the other hand, if there is an abnormality such that the second switch S2 is closed or short-circuited due to a failure or the like, a circuit is formed in which the capacitor 9 is connected in series with the power supply 3, and as shown in FIG. During the first closing time T1, the capacitor 9 is charged, and the voltage VC between both terminals of the capacitor 9 increases. Therefore, when the switch S3 and the fourth switch S4 are closed and the microcomputer 11 reads the voltage VC between both terminals of the capacitor 9 via the A / D port, the capacitor 9 is charged due to the abnormality of the second switch S2. Therefore, the microcomputer 11 detects a voltage corresponding to the voltage VC between both terminals of the capacitor 9. When the voltage corresponding to the voltage VC between both terminals of the capacitor 9 is detected, the microcomputer 11 as the abnormality detecting means determines that the second switch S2 is abnormal, and stops measuring the insulation resistance value, for example. Notify an abnormality by alarm.
[0027]
In the first switch abnormality detecting step 107, as shown in FIG. 4, the second switch S2 is closed for a first closing time T1, which is a first set time, for example, in a state where the other switches are shut off. At this time, if there is no abnormality in the first switch S1, a circuit for connecting the capacitor 9 to the power supply 3 in series is not formed, and the voltage VC between both terminals of the capacitor 9 does not increase. After the lapse of the first closing time T1, the third switch S3 and the fourth switch S4 are closed after a lapse of a predetermined time tw1 shorter than the first closing time T1. That is, the fourth switching means forms a circuit to which the microcomputer 11 for detecting the voltage between both terminals of the capacitor 9 is connected, and the capacitor including the second resistor R2, the third resistor R3, and the fourth resistor R4. 9 to form a discharge circuit. Here, when the microcomputer 11 reads the voltage VC between both terminals of the capacitor 9 via the A / D port, the voltage is not detected by the microcomputer 11 because the capacitor 9 is not charged. Since the voltage is not detected by the microcomputer 11, the microcomputer 11 as the abnormality detecting means determines that the first switch S1 has no abnormality.
[0028]
Thereafter, the switching control circuit (not shown) closes the fifth switch S5 with the third switch S3 and the fourth switch S4 closed after the microcomputer 11 detects the voltage VC between both terminals of the capacitor 9 by the microcomputer 11. To bypass the second resistor R2. As a result, the resistance value of the second resistor R2 is reduced, and the time required for discharging from the capacitor 9 is reduced. After the fifth switch S5 is closed and a predetermined time td1 shorter than the first closed time T1 has elapsed, the fifth switch S5 is opened or shut off, and then the microcomputer 11 outputs the A / D converted data via the A / D port. That is, the voltage VC between both terminals of the capacitor 9 is read, and it is confirmed that the voltage VC is 0V.
[0029]
On the other hand, when there is an abnormality such as the first switch S1 being in a closed state or a short circuit state due to a failure or the like, a circuit in which the capacitor 9 is connected in series to the power supply 3 is formed, and as shown in FIG. During the first closing time T1, the capacitor 9 is charged, and the voltage VC between both terminals of the capacitor 9 increases. Therefore, when the switch S3 and the fourth switch S4 are closed and the microcomputer 11 reads the voltage VC between both terminals of the capacitor 9 via the A / D port, the capacitor 9 is charged due to the abnormality of the first switch S1. Therefore, the microcomputer 11 detects a voltage corresponding to the voltage VC between both terminals of the capacitor 9. When the voltage corresponding to the voltage VC between both terminals of the capacitor 9 is detected, the microcomputer 11 as the abnormality detecting means determines that the first switch S1 is abnormal, and stops measuring the insulation resistance value, for example. Notify an abnormality by alarm.
[0030]
The third switch abnormality detection step 109 and the fourth switch abnormality detection step 111 are performed as one step in the present embodiment. In the third switch abnormality detection step 109 and the fourth switch abnormality detection step 111, as shown in FIG. 4, the first switch S1 and the second switch S2 are, for example, set to a first set time while other switches are shut off. The circuit is closed for the first closing time T1. That is, a circuit for connecting the capacitor 9 in series with the power supply 3 is formed by the first switching means, and the capacitor 9 is charged during the first closing time T1. As a result, the voltage VC between both terminals of the capacitor 9 increases. After the lapse of the first closing time T1, the fourth switch S4 is closed with the third switch S3 shut off in order to detect the abnormality of the third switch S3 after the lapse of a predetermined time tw1 shorter than the first closing time T1. .
[0031]
At this time, if there is no abnormality in the third switch S3, the circuit to which the microcomputer 11 for detecting the voltage between both terminals of the capacitor 9 is connected, and the second resistor R2, the third resistor R3, and the fourth resistor R4 are connected. No discharge circuit is formed from the capacitor 9 including the capacitor. Here, when the microcomputer 11 reads the voltage VC between both terminals of the capacitor 9 via the A / D port, no voltage is applied to the A / D port of the microcomputer 11 and the microcomputer 11 does not detect the voltage. Since the voltage is not detected by the microcomputer 11, the microcomputer 11 as the abnormality detecting means determines that the third switch S3 has no abnormality.
[0032]
Subsequently, after a predetermined time tw1 has elapsed since the third switch S3 was closed and the third switch S3 was closed, in order to detect an abnormality of the fourth switch S4, the fourth switch S3 was closed and the fourth switch S3 was closed. Cut off S4. At this time, if there is no abnormality in the fourth switch S4, the circuit to which the microcomputer 11 for detecting the voltage between both terminals of the capacitor 9 is connected, and the second resistor R2, the third resistor R3, and the fourth resistor R4 are connected. No discharge circuit is formed from the capacitor 9 including the capacitor. Here, when the microcomputer 11 reads the voltage VC between both terminals of the capacitor 9 via the A / D port, no voltage is applied to the A / D port of the microcomputer 11 and the microcomputer 11 does not detect the voltage. Since the voltage is not detected by the microcomputer 11, the microcomputer 11 as the abnormality detecting means determines that the fourth switch S4 has no abnormality.
[0033]
Thereafter, the switching control circuit (not shown) reads the data at the A / D port of the microcomputer 11 and then closes the fifth switch S5 with the third switch S3 and the fourth switch S4 closed. The second resistor R2 is bypassed. As a result, the resistance value of the second resistor R2 is reduced, and the time required for discharging from the capacitor 9 is reduced. After the fifth switch S5 is closed and a predetermined time td1 shorter than the first closed time T1 has elapsed, the fifth switch S5 is opened or shut off, and then the microcomputer 11 outputs the A / D converted data via the A / D port. That is, the voltage VC between both terminals of the capacitor 9 is read, and it is confirmed that the voltage VC is 0V. Proceed to the insulation resistance measurement step 113.
[0034]
On the other hand, when there is an abnormality such as the third switch S3 being in a closed state or a short circuit state due to a failure or the like, a state is formed in which a circuit to which the microcomputer 11 for detecting the voltage between both terminals of the capacitor 9 is connected is formed. , The second resistor R2, the third resistor R3, and the fourth resistor R4. Therefore, when the microcomputer 11 reads the voltage VC between both terminals of the capacitor 9 via the A / D port, as shown in FIG. 7, the abnormality of the third switch S3 causes the capacitor 9 to be connected to the A / D port of the microcomputer 11. Since the voltage VC between both terminals is applied, the microcomputer 11 detects a voltage corresponding to the voltage VC between both terminals of the capacitor 9. When the voltage corresponding to the voltage VC between both terminals of the capacitor 9 is detected, the microcomputer 11 as the abnormality detecting means determines that the third switch S3 is abnormal, and stops measuring the insulation resistance value, for example. Notify an abnormality by alarm.
[0035]
Further, when there is an abnormality such as the fourth switch S4 being in a closed state or a short circuit state due to a failure or the like, a state is formed in which a circuit to which the microcomputer 11 for detecting the voltage between both terminals of the capacitor 9 is connected is formed. , The second resistor R2, the third resistor R3, and the fourth resistor R4. Therefore, when the microcomputer 11 reads the voltage VC between both terminals of the capacitor 9 via the A / D port, as shown in FIG. 8, the abnormality of the fourth switch S4 causes the capacitor 9 to be connected to the A / D port of the microcomputer 11. Since the voltage VC between both terminals is applied, the microcomputer 11 detects a voltage corresponding to the voltage VC between both terminals of the capacitor 9. When the voltage corresponding to the voltage VC between both terminals of the capacitor 9 is detected, the microcomputer 11 as the abnormality detecting means determines that the fourth switch S4 is abnormal, and stops measuring the insulation resistance value, for example. Notify an abnormality by alarm.
[0036]
FIGS. 7 and 8 are different from FIG. 4 in that the third switch abnormality detection step 109 and the fourth switch abnormality detection step 111 are individually performed, and the third switch abnormality detection step is performed. Step 109 shows a method of closing only the third switch S3 after closing the third switch S3 and the fourth switch S4 at the same time.
[0037]
When no switch abnormality is detected in each of the switch abnormality detection steps 105, 107, 109, and 111, that is, when it is detected that the power supply voltage itself is abnormal, or as shown in FIGS. 2 and 4, If no power supply voltage abnormality is detected in the power supply voltage abnormality determination 103, the process proceeds to the insulation resistance measuring step 113. In the insulation resistance measuring step 113, the switching control circuit (not shown) switches the first switch S1 and the fourth switch S4 during the second closed time T2, which is the second set time, as shown in FIGS. Is closed (step 301).
[0038]
That is, a circuit in which the capacitor 9 is connected in series between the positive terminal of the power supply 3 and the ground potential unit 7 by the second switching means, that is, as shown in FIG. The switch S1, the first diode D1, the first resistor R1, the capacitor 9, the fourth switch S4, the fourth resistor R4, the ground potential unit 7, and the ground on the negative terminal side assumed at a position shown by a dotted line in FIG. A circuit is formed in which the short-circuit resistance Rn and the negative-side main circuit wiring 5b are sequentially connected in series to the power supply 3. Thereby, the capacitor 9 is charged during the second closing time T2, and as shown in FIG. 4, the voltage VC between both terminals of the capacitor 9 increases according to the value of the ground fault resistance Rn. Note that the second closed time T2, which is the second set time, is also shorter than the time required for completely charging the capacitor 9 and longer than the predetermined times tw1, td1, similarly to the first closed time T1. Is set to
[0039]
When the second closing time T2 elapses in step 301, as shown in FIGS. 4 and 9, the first switch S1 is opened or shut off, and after the lapse of a predetermined time tw1, the third switch S3 is closed and the third switch S3 is opened. And the fourth switch S4 is closed. That is, the fourth switching means forms a circuit to which the microcomputer 11 for detecting the voltage between both terminals of the capacitor 9 is connected, and includes the second resistor R2, the third resistor R3, and the fourth resistor R4. A discharge circuit from the capacitor 9 is formed, and the voltage VC between both terminals of the capacitor 9 drops. Then, the microcomputer 11 reads the A / D conversion data, that is, the voltage VC between both terminals of the capacitor 9 via the A / D port (Step 303). Based on the value of the voltage VC between both terminals of the capacitor 9 at this time, that is, the detection voltage VCN, the insulation resistance with respect to the vehicle body or the like which becomes the ground potential portion 7 on the negative terminal side of the power supply 3 from the following equation (2), that is, the ground on the negative terminal side A short-circuit resistance Rn is calculated (step 305).
Rn = -R1-T2 / C.ln (1-VCN / V0s) (2)
In the equation (2), T2 is the closing time of the first switch S1 and the fourth switch S4, C is the capacitance of the capacitor 9, R1 is the resistance value of the first resistor R1, and the power supply voltage V0s is the power supply voltage estimation process 101. This is the estimated power supply voltage.
[0040]
On the other hand, the switching control circuit (not shown) detects the voltage VC between both terminals of the capacitor 9 in step 305, and then closes the fifth switch S5 with the third switch S3 and the fourth switch S4 closed. By bypassing the second resistor R2, the resistance value of the second resistor R2 is reduced, and the time required for discharging from the capacitor 9 is reduced. After closing the fifth switch S5 and elapse of a predetermined time td2 shorter than the second closing time T2, the third switch S3, the fourth switch S4, and the fifth switch S5 are opened or shut off, and then the microcomputer 11 sets the A / A A / D conversion data, that is, a voltage VC between both terminals of the capacitor 9 is read through the D port (step 307).
[0041]
If it is confirmed in step 307 that the voltage VC is 0 V, the switching control circuit (not shown) closes the second switch S2 and the third switch S3 for the second set time, that is, the second closed time T2. (Step 309). That is, a circuit in which the capacitor 9 is connected in series between the ground potential section 7 and the negative terminal of the power supply 3 by the third switching means, that is, as shown in FIG. , A ground fault resistor Rp on the positive terminal side assumed at a position indicated by a dotted line, a ground potential portion 7, a third resistor R3, a third switch S3, a first diode D1, a first resistor R1, a capacitor 9, and a second A circuit is formed in which the switch S2 and the negative-side main circuit wiring 5b are sequentially connected in series to the power supply 3. Thereby, the capacitor 9 is charged during the second closing time T2, and as shown in FIG. 4, the voltage VC between both terminals of the capacitor 9 increases according to the value of the ground fault resistance Rp.
[0042]
When the second closing time T2 elapses in step 309, as shown in FIGS. 4 and 9, the second switch S2 is opened or shut off, and after the elapse of the predetermined time tw1, the fourth switch S4 is closed and the third switch S3 is opened. And the fourth switch S4 is closed. That is, the fourth switching means forms a circuit to which the microcomputer 11 for detecting the voltage between both terminals of the capacitor 9 is connected, and includes the second resistor R2, the third resistor R3, and the fourth resistor R4. A discharge circuit from the capacitor 9 is formed, and the voltage VC between both terminals of the capacitor 9 drops. Then, the microcomputer 11 reads the A / D conversion data via the A / D port, that is, the voltage VC between both terminals of the capacitor 9 (Step 311). Based on the value of the voltage VC between both terminals of the capacitor 9 at this time, that is, the detection voltage VCP, the insulation resistance to the vehicle body or the like which becomes the ground potential portion 7 on the positive terminal side of the power supply 3 from the following equation (3), that is, the ground on the positive terminal side The short-circuit resistance Rp is calculated (step 313).
Rp = -R1-T2 / C.ln (1-VCP / V0s) (3)
In the equation (3), T2 is the closing time of the second switch S2 and the third switch S3, C is the capacitance of the capacitor 9, R1 is the resistance value of the first resistor R1, and the power supply voltage V0s is the power supply voltage estimation process 101. This is the estimated power supply voltage.
[0043]
On the other hand, the switching control circuit (not shown) detects the voltage VC between both terminals of the capacitor 9 in step 313, and then closes the fifth switch S5 with the third switch S3 and the fourth switch S4 closed. By bypassing the second resistor R2, the resistance value of the second resistor R2 is reduced, and the time required for discharging from the capacitor 9 is reduced. After a predetermined time td2 has elapsed after closing the fifth switch S5, the third switch S3, the fourth switch S4, and the fifth switch S5 are opened or shut off, and then the microcomputer 11 performs A / D conversion via the A / D port. The data, that is, the voltage VC between both terminals of the capacitor 9 is read (step 315). Then, when it is confirmed in step 315 that the voltage VC is 0 V, one insulation state detection cycle ends. During the detection of the insulation state, the detection cycle from the process 101 of measuring the insulation resistance to the step 113 shown in FIGS. 2, 3 and 9 is repeated.
[0044]
The microcomputer 11 determines the insulation state from the value of the ground fault resistance Rp on the positive terminal side of the power supply 3 and the value of the ground fault resistance Rn on the negative terminal side obtained in one insulation state detection cycle. For example, the ground fault resistance Rp on the positive terminal side of the power supply 3 is compared with a predetermined reference resistance value. If the ground fault resistance Rp is equal to or less than the reference resistance value, insulation failure has occurred. Is determined.
[0045]
By the way, as can be seen from the equations (2) and (3), if the capacitance C of the capacitor 9 and the resistance value R1 of the first resistor R1 vary due to a difference between products or a temperature change, the positive terminal side of the power supply 3 is changed. The measurement accuracy of the ground fault resistance Rp and the ground fault resistance Rn on the negative terminal side is affected, and the accuracy of the detected ground fault resistances Rp and Rn is reduced. Therefore, the detection accuracy of the insulation state is reduced. In particular, since the capacitor 9 needs to have a relatively large value of several μF in consideration of the stray capacitance, for example, if there is a variation of about ± 5% in the difference between products, it is ± 10% in consideration of a temperature change. % In some cases, and such variation in the capacitance of the capacitor 9 reduces the detection accuracy of the insulation state. In addition, variations caused by changes in component constants due to changes over time also lower the detection accuracy of the insulation state.
[0046]
On the other hand, in the insulation detection device 1 of the present embodiment, the first switch S1 and the second switch S2 in the first stage of the insulation detection cycle are set to the first switch S1 and the second switch S2, which are shorter than the time required to completely charge the capacitor 9. By closing the circuit for the closing time T1, the power supply voltage of the power supply 3 is estimated. When charging the capacitor 9 by closing the first switch S1 and the second switch S2 for a short time, when charging is performed with a time constant C · R1 determined by the actual capacitance of the capacitor 9 and the resistance value of the resistor R1. The estimated power supply voltage V0s is not an actual power supply voltage of the power supply 3 but a value including an error between the capacitance and resistance value of the capacitor 9 and the resistor R1, that is, a value including variation. . Then, the estimated power supply voltage V0s including this variation is used in the calculation of the ground fault resistance Rp on the positive terminal side and the ground fault resistance Rn on the negative terminal side to be performed in the subsequent steps in the cycle of insulation detection. Of the capacitance of the capacitor 9, the actual values of the positive terminal side ground fault resistance Rp and the negative terminal side ground fault resistance Rn, and the calculated positive terminal side ground fault resistance Rp and negative value. An error with the value of the terminal-side ground fault resistance Rn can be reduced. Therefore, the detection accuracy of the insulation state can be improved.
[0047]
The values of the ground fault resistance Rp on the positive terminal side and the ground fault resistance Rn on the negative terminal side measured by the insulation detection device 1 of the present embodiment and the actual ground fault resistance Rp on the positive terminal side and the actual ground fault resistance Rp on the negative terminal side are measured. FIG. 10 shows a result of calculating an error from the value of the ground fault resistor Rn on the assumption that the capacitor 9 having a certain predetermined standard capacity and the first resistor R1 having a certain predetermined standard resistance value are used. The capacitor 9 has a capacitance variation of about ± 10% in consideration of the difference between products and the temperature change, and the first resistor R1 has a capacitance variation of about ± 2% in consideration of the difference between products and the temperature change. It is assumed that there is. In FIG. 10, the V0 measurement time means the first closed time, and therefore, in FIG. 4, the measurement is performed when the first closed time T1 is t seconds, 2t seconds, and 3t seconds, where t <2t <3t. The error is shown. FIG. 10 is a graph in which the calculation results are plotted with the vertical axis representing the detection accuracy, that is, the detection error, and the horizontal axis representing the value of the ground fault resistance.
[0048]
As can be seen from FIG. 10, the case where the detection is performed by the insulation detection device 1 of the present embodiment, that is, the case with the correction, is larger than the case where the detection is performed by the conventional insulation detection device, that is, the case without the correction. The measurement error is reduced with respect to the value. Further, the degree of reduction of the measurement error varies depending on the setting of the V0 measurement time, that is, the setting of the first closing time T1, and when the first closing time T1 is t seconds, the error increases as the ground fault resistance decreases. The error decreases as the resistance increases. When the first closing time T1 is 2t seconds, when the ground fault resistance is large, the error becomes larger than when the first closing time T1 is t seconds, but the error becomes smaller on average over the short-circuit resistance in each place. I have. Even when the first closing time T1 is 3 t seconds, the error is smaller on average across the short-circuit resistance, but the error is larger than when the first closing time T1 is 2 t seconds.
[0049]
Therefore, when the value of the ground fault resistance for determining the insulation failure is set to a relatively large value, the first closing time T1 is preferably set to t seconds. When the setting is a relatively small value, the first closing time T1 is preferably set to 2t seconds. As described above, it is preferable that the first closing time T1, that is, the first set time, is selected such that the measurement error becomes small around the value of the ground fault resistance for determining the insulation failure. For example, if the value of the ground fault resistance for determining insulation failure is set to RΩ in FIG. 10, it is preferable to select 2t seconds as the first closing time T1. %, Whereas the insulation detection device 1 of the present embodiment has a measurement error of ± 2% or less, and the insulation state detection accuracy can be improved.
[0050]
As described above, in the insulation detecting device 1 of the present embodiment, the microcomputer 11 serving as the abnormality detecting means is the first, second, third, and fourth switching units constituting the first, second, and fourth switching means. Since the second, third, and fourth switches S1, S2, S3, and S4 are individually inspected to determine the abnormality, the switch in which the abnormality has occurred can be specified.
[0051]
In this embodiment, the first switch abnormality detection step 107, the second switch abnormality detection step 105, the third switch abnormality detection step 109, and the fourth switch abnormality detection step 111 are performed after the power supply voltage estimation step 101. The switch abnormality detection steps 105, 107, 109, and 111 may be performed at any point in the insulation resistance measurement step. Further, the order in which the first switch abnormality detection step 107, the second switch abnormality detection step 105, the third switch abnormality detection step 109, and the fourth switch abnormality detection step 111 are performed can be appropriately changed.
[0052]
However, as in the present embodiment, if the power supply voltage estimation process 101 is first performed and the power supply voltage abnormality determination 103 is performed, and then the switch abnormality detection processes 105, 107, 109, and 111 are performed according to the result, it is wasteful. Anomaly detection can be performed efficiently without performing any anomaly detection operation, and the measurement time of the insulation resistance can be reduced. In addition, since the results of the third switch abnormality detection step 109 and the fourth switch abnormality detection step 111 are affected by the states of the first switch S1 and the second switch S2, the first switch abnormality detection step 107 and the second switch After performing the abnormality detection step 105, it is desirable to perform the third switch abnormality detection step 109 and the fourth switch abnormality detection step 111. At this time, the order of the first switch abnormality detection step 107 and the second switch abnormality detection step 105 and the order of the third switch abnormality detection step 109 and the fourth switch abnormality detection step 111 can be changed as appropriate.
[0053]
Further, in the present embodiment, the ground fault resistance Rp on the positive terminal side and the ground fault resistance Rn on the negative terminal side are individually calculated, so that a portion having insulation failure can be detected. However, in the case where only the occurrence of insulation failure is determined without detecting the location of insulation failure, for example, the ground fault resistance Rp on the positive terminal side and the negative terminal on the basis of the estimated power supply voltage V0s and the detection voltages VCP, VCN, etc. Another formula for calculating a ground fault resistance value or the like representing the ground fault resistance Rn on the side can also be used.
[0054]
In addition, in the insulation detection device 1 of the present embodiment, the power supply voltage V0s and the ground-fault resistance values Rn and Rp estimated by the equations (1), (2), and (3) are calculated by the microcomputer 11 serving as the calculating means. I have. However, in order to reduce the time required for calculating these complex function expressions such as Expressions (1), (2), and (3), the power supply estimated in accordance with the address in a memory or the like serving as storage means of the microcomputer 11 is used. A power supply voltage data table or a ground fault resistance value data table storing the voltage V0s, the ground fault resistance values Rn, Rp, and the like are prepared, and an address corresponding to each data table is calculated by the microcomputer 11 which is a calculating means. It can also be configured. At this time, the microcomputer 11 which is a calculating means obtains the value of the voltage VC between both terminals of the capacitor 9 detected for estimating the power supply voltage, that is, the detected voltage V0, the estimated power supply voltage V0s, and the ground fault resistance values Rn and Rp. Therefore, from the value of the voltage VC between both terminals of the capacitor 9 detected, that is, the detected voltages VCN, VCP, and the like, each of the power supply voltages is calculated by an arithmetic expression of an address which is simpler than the expressions (1), (2), and (3). The address of the data table and the address of the ground fault resistance data table are calculated, and the power supply voltage V0s and the ground fault resistances Rn and Rp estimated from the calculated addresses are determined.
[0055]
Further, the bypass unit including the fifth switch S5 is not limited to the configuration of the present embodiment, and the bypass unit is provided between the two terminals of the second resistor R2 in parallel with the second resistor R2, as shown in FIG. A configuration in which the fifth switch S5 is connected may be employed. Further, when there is no need to shorten the time required for one cycle for insulation detection or the like, a configuration without the bypass unit including the fifth switch S5 can be adopted.
[0056]
In addition, the present invention is not limited to the circuit configuration shown in the present embodiment, and a capacitor is connected in series to a DC power supply whose positive terminal side and negative terminal side wiring are insulated from the ground potential portion for a first set time. First switching means, second switching means for connecting the capacitor in series between the positive terminal of the power supply and the ground potential section for a second set time, and between the negative terminal of the power supply and the ground potential section A third switching means for connecting a capacitor in series for a second set time, and a detecting means for detecting a voltage between both terminals of the capacitor after the first, second and third switching means are cut off. If it has the fourth switching means and the like, it can be applied to insulation detection devices having various circuit configurations.
[0057]
【The invention's effect】
According to the present invention, a switch in which an abnormality has occurred can be specified.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an embodiment of an insulation detection device to which the present invention is applied.
FIG. 2 is a flowchart showing an operation of measuring insulation resistance of an embodiment of an insulation detection device to which the present invention is applied.
FIG. 3 is a flowchart showing an operation of a power supply voltage estimation process of an embodiment of the insulation detection device to which the present invention is applied.
FIG. 4 is a time chart showing a charge / discharge state of a capacitor and a voltage reading timing with respect to the operation of each switch unit when the power supply voltage is normal and abnormal.
FIG. 5 is a time chart showing a charge / discharge state of a capacitor and a voltage reading timing with respect to an operation of each switch unit in a process of detecting an abnormality of a second switch.
FIG. 6 is a time chart showing a charge / discharge state of a capacitor and a voltage reading timing with respect to an operation of each switch unit in a process of detecting an abnormality of a first switch.
FIG. 7 is a time chart showing a charging / discharging state of a capacitor and a voltage reading timing with respect to an operation of each switch unit in a process of detecting an abnormality of a third switch.
FIG. 8 is a time chart showing a charge / discharge state of a capacitor and a voltage reading timing with respect to an operation of each switch unit in a process of detecting an abnormality of a fourth switch.
FIG. 9 is a flowchart showing an operation of an insulation resistance measuring process of an embodiment of the insulation detection device to which the present invention is applied.
FIG. 10 is a diagram illustrating a detection error of an insulation resistance value detected during a measurement time of each power supply voltage with respect to the insulation resistance value.
FIG. 11 is a diagram showing a schematic configuration of a modification of the insulation detection device to which the present invention is applied.
[Explanation of symbols]
1 Insulation detection device
3 power supply
5a Positive main circuit wiring
5b Negative main circuit wiring
7 Ground potential section
9 Capacitor
11 microcomputer
S1 First switch
S2 Second switch
S3 3rd switch
S4 4th switch
Rp Positive terminal side ground fault resistance
Rn Negative terminal side ground fault resistance

Claims (1)

正端子側及び負端子側の配線が接地電位部から絶縁された直流電源にコンデンサを直列に、該コンデンサが完全に充電される時間よりも短い第１の設定時間の間接続する第１のスイッチング手段と、前記電源の正端子と前記接地電位部との間に前記コンデンサを直列に第２の設定時間の間接続する第２のスイッチング手段と、前記電源の負端子と前記接地電位部との間に前記コンデンサを直列に第２の設定時間の間接続する第３のスイッチング手段と、前記第１、第２及び第３の各スイッチング手段の遮断後に前記コンデンサの両端子間の電圧を検出する電圧検出手段を接続する第４のスイッチング手段と、前記第１のスイッチング手段を遮断後の前記電圧検出手段での検出電圧に基づいて前記電源の電源電圧を推定し、該推定した電源電圧と前記第２及び第３のスイッチング手段を遮断後の前記電圧検出手段での各検出電圧とに基づいて前記電源の前記接地電位部に対する絶縁抵抗を求める演算手段と、前記第１、第２、第３及び第４のスイッチング手段で生じた異常を検出する異常検出手段１１とを備え、
前記第１のスイッチング手段が、前記電源の正端子に接続された第１のスイッチ部と、前記電源の負端子に接続された第２のスイッチ部とを含み、前記第３のスイッチング手段が、前記第２のスイッチ部と、前記第１のスイッチに直列に接続された第３のスイッチ部とを含み、前記第２のスイッチング手段が、前記第１のスイッチ部と、前記第２のスイッチ部に直列に接続された第４のスイッチ部とを含み、前記第４のスイッチング手段が、前記第３のスイッチ部と前記第４のスイッチ部とを含み、前記第１のスイッチ部と前記第３のスイッチ部との間と、前記第２のスイッチ部と前記第４のスイッチ部との間とに、正側から負側に向かう方向に整流する第１のダイオード及び前記コンデンサを直列に接続し、前記第１のダイオードに並列に、該第１ダイオードと逆方向に整流する第２のダイオードを接続し、前記電圧検出手段を前記第３のスイッチ部と前記第４のスイッチ部との間に接続し、前記電圧検出手段と前記第４のスイッチ部との間を前記接地電位部に接地しており、
前記異常検出手段は、前記第２のスイッチ部のみを第３の設定時間の間閉路した後、前記第４のスイッチング手段を閉路したときの前記電圧検出手段での検出電圧に基づいて前記第１のスイッチ部の異常を判定し、前記第１のスイッチ部のみを第４の設定時間の間閉路した後、前記第４のスイッチング手段を閉路したときの前記電圧検出手段での検出電圧に基づいて前記第２のスイッチ部の異常を判定し、前記第１のスイッチング手段を第５の設定時間の間閉路した後、前記第３のスイッチ部を遮断及び前記第４のスイッチ部を閉路したときの前記電圧検出手段での検出電圧に基づいて前記第３のスイッチ部の異常を判定し、前記第１のスイッチング手段を第６の設定時間の間閉路した後、前記第３のスイッチ部を閉路及び前記第４のスイッチ部を遮断したときの前記電圧検出手段での検出電圧に基づいて前記第４のスイッチ部の異常を検出してなる非接地電源の絶縁検出装置。First switching in which a capacitor is connected in series to a DC power supply whose wiring on the positive terminal side and the negative terminal side are insulated from the ground potential portion for a first set time shorter than the time when the capacitor is completely charged Means, a second switching means for connecting the capacitor in series between a positive terminal of the power supply and the ground potential section for a second set time, and a second switching means for connecting the negative terminal of the power supply and the ground potential section. A third switching means for connecting the capacitor in series for a second set time, and detecting a voltage between both terminals of the capacitor after the first, second and third switching means are shut off. A fourth switching means for connecting a voltage detecting means, and a power supply voltage of the power supply is estimated based on a voltage detected by the voltage detecting means after the first switching means is cut off. Calculating means for determining an insulation resistance of the power supply with respect to the ground potential portion based on the respective detected voltages of the voltage detecting means after the second and third switching means have been cut off; Abnormality detecting means 11 for detecting abnormality occurring in the third and fourth switching means,
The first switching unit includes a first switch unit connected to a positive terminal of the power supply, and a second switch unit connected to a negative terminal of the power supply, wherein the third switching unit includes: The second switch unit; and a third switch unit connected in series to the first switch, wherein the second switching unit includes the first switch unit and the second switch unit. A fourth switch unit connected in series with the first switch unit, the fourth switching unit includes the third switch unit and the fourth switch unit, and the first switch unit and the third switch unit. A first diode and the capacitor, which rectify in the direction from the positive side to the negative side, are connected in series between the first switch section and the second switch section and between the second switch section and the fourth switch section. , In parallel with the first diode The first diode is connected to a second diode that rectifies in the opposite direction, the voltage detection unit is connected between the third switch unit and the fourth switch unit, and the voltage detection unit is connected to the second diode. 4 is grounded to the ground potential section, and
The abnormality detecting means closes only the second switch unit for a third set time, and then, based on a voltage detected by the voltage detecting means when the fourth switching means is closed, based on the first voltage. Is determined based on the voltage detected by the voltage detection unit when the fourth switching unit is closed after the first switching unit is closed for a fourth set time. After the abnormality of the second switch is determined, the first switch is closed for a fifth set time, and then the third switch is turned off and the fourth switch is closed. An abnormality of the third switch unit is determined based on a voltage detected by the voltage detection unit, and after the first switching unit is closed for a sixth set time, the third switch unit is closed and closed. The fourth switch Department said voltage on the basis of the detection voltage by the detection means comprising detecting an abnormality of the fourth switch unit ungrounded power insulating detecting device when blocked.
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