JP2007089277A - Leak detector for electric car - Google Patents

Leak detector for electric car Download PDF

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JP2007089277A
JP2007089277A JP2005273503A JP2005273503A JP2007089277A JP 2007089277 A JP2007089277 A JP 2007089277A JP 2005273503 A JP2005273503 A JP 2005273503A JP 2005273503 A JP2005273503 A JP 2005273503A JP 2007089277 A JP2007089277 A JP 2007089277A
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capacitor
resistor
leak
output
operational amplifier
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Akihiko Kudo
彰彦 工藤
Masaki Nagaoka
正樹 長岡
Kenichiro Tsuru
憲一朗 水流
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Vehicle Energy Japan Inc
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Hitachi Vehicle Energy Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/52—Testing for short-circuits, leakage current or ground faults
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]

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  • General Physics & Mathematics (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
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  • Electric Propulsion And Braking For Vehicles (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leak detector which can detect low leak resistance without raising the measured frequency or the capacity of a capacitor. <P>SOLUTION: The leak detector 20 impresses the rectangular waves of constant voltage amplitude from the output port of a microcomputer 5 to between a group of batteries 1 and a chassis ground via a capacitor 3, and measures the current flowing in the capacitor 3 thereby detecting the leakage between the car body and the group of batteries 1. To measure the current flowing in the capacitor 3, the output from the output port of the microcomputer 5 is connected to the positive-phase input of an operational amplifier 11, and the output of the operational amplifier 11 is connected with the capacitor 3 via a resistor 11 for current detection, and besides the junction between the capacitor 3 and the resistor 11 for current detection is connected to the reverse-phase input of the operational amplifier 11, and further the voltage across the resistor 11 for current detection is inputted into the differential amplifier which is composed an operational amplifier 16 and resistors 12-15, and the output voltage of the differential amplifier is detected. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は電気自動車のリーク検出装置に係り、特に、車体と電気的に絶縁された直流電源回路と車体に接地された車両電装回路とを有する電気自動車のリーク検出装置に関する。   The present invention relates to a leak detection device for an electric vehicle, and more particularly to a leak detection device for an electric vehicle having a DC power supply circuit electrically insulated from the vehicle body and a vehicle electrical circuit grounded to the vehicle body.

従来、電気自動車（ＰＥＶ）やハイブリッド電気自動車（ＨＥＶ）等には、一般に、高電圧の電池群を直列に接続した直流電源回路と車体に接地された車両電装回路とが搭載されており、両者は絶縁されている。また、直流電源回路と車体との間に絶縁破壊が生じリーク電流が流れた場合にリークを検出するリーク検出装置が搭載されている。このような、リーク検出装置は、高電圧の直流電源端子にコンデンサと抵抗の直列回路を接続し、信号波を抵抗側に印加して、コンデンサと抵抗との接続点に発生する交流電圧成分の振幅からリークを検出するリーク検出回路を有している（例えば、特許文献１参照）。   Conventionally, an electric vehicle (PEV), a hybrid electric vehicle (HEV), and the like generally include a DC power supply circuit in which high-voltage battery groups are connected in series and a vehicle electrical circuit grounded to the vehicle body. Is insulated. In addition, a leak detection device is mounted that detects a leak when a dielectric breakdown occurs between the DC power supply circuit and the vehicle body and a leak current flows. Such a leak detection device connects a series circuit of a capacitor and a resistor to a high-voltage DC power supply terminal, applies a signal wave to the resistor side, and generates an AC voltage component generated at the connection point between the capacitor and the resistor. It has a leak detection circuit that detects a leak from the amplitude (see, for example, Patent Document 1).

図２は、上記リーク検出回路の基本構成を示したものである。高電圧の電池群１が負荷２に接続されており、電極群１の＋端子はリーク検出用コンデンサ３を通じて抵抗４に接続されている。抵抗４はリーク検出を行うマイクロコンピュータ（以下、マイコンという。）５の出力ポートに接続されている。抵抗４とコンデンサ３との接続点から、抵抗６とコンデンサ７とのＲＣフィルタを通じてバッファ８の入力に接続されており、バッファ８の出力はマイコン５のＡＤ入力に接続されている。リーク検出回路の動作電源（不図示）のグランドは車両の車体（シャーシグラウンド）に接続されており、電池群１及び負荷２とは絶縁されている。なお、抵抗６とコンデンサ７とのＲＣフィルタは車両で発生するノイズ成分を削減するためのものである。   FIG. 2 shows the basic configuration of the leak detection circuit. A high voltage battery group 1 is connected to a load 2, and a positive terminal of the electrode group 1 is connected to a resistor 4 through a leak detection capacitor 3. The resistor 4 is connected to an output port of a microcomputer (hereinafter referred to as a microcomputer) 5 that performs leak detection. A connection point between the resistor 4 and the capacitor 3 is connected to an input of the buffer 8 through an RC filter of the resistor 6 and the capacitor 7, and an output of the buffer 8 is connected to an AD input of the microcomputer 5. The ground of the operating power supply (not shown) of the leak detection circuit is connected to the vehicle body (chassis ground) of the vehicle, and is insulated from the battery group 1 and the load 2. Note that the RC filter of the resistor 6 and the capacitor 7 is for reducing noise components generated in the vehicle.

リーク検出動作は、マイコン５の出力ポートから矩形波が出力され、ＡＤ入力で応答波形の振幅を測定することで行われる。リーク抵抗９が無限大であれば、コンデンサ３には交流電流成分が流れないので、矩形波は抵抗６とコンデンサ７のＲＣフィルタを通ってＡＤ入力に入るだけである。その場合、振幅はＲＣフィルタで多少矩形波より減少するが大きいままである。一方、リーク抵抗９が小さくなれば、コンデンサ３を通じて交流電流が流れるため、抵抗４とコンデンサ３の接続点の振幅はマイコン５の出力ポートの波形よりも小さくなり、ＡＤ入力で測定される波形の振幅も小さくなる。リークは直流電源回路のどこで起こるかわからないが、電池のインピーダンスは非常に小さいため、電池群１の＋端子側で発生しても、−端子側で発生しても、又は、中間の接続点で発生しても検出波形に与える影響は小さくリークの検出が可能である。   The leak detection operation is performed by outputting a rectangular wave from the output port of the microcomputer 5 and measuring the amplitude of the response waveform with the AD input. If the leak resistance 9 is infinite, no AC current component flows through the capacitor 3, so the rectangular wave only enters the AD input through the resistor 6 and the RC filter of the capacitor 7. In that case, the amplitude is slightly reduced by the RC filter than the rectangular wave, but remains large. On the other hand, if the leak resistance 9 is reduced, an alternating current flows through the capacitor 3, so that the amplitude of the connection point between the resistor 4 and the capacitor 3 is smaller than the waveform of the output port of the microcomputer 5, and the waveform measured by the AD input The amplitude is also reduced. I do not know where the leakage occurs in the DC power supply circuit, but the impedance of the battery is so small that it can occur on the + terminal side of the battery group 1, on the-terminal side, or at an intermediate connection point. Even if it occurs, the influence on the detected waveform is small, and a leak can be detected.

図３は、このリーク検出回路で、リーク抵抗９の抵抗値により、どのように出力波形が変化するかを計算した結果を示したものである。抵抗４の値は４３ｋΩ、コンデンサ３の値は２．２μＦ、抵抗６の値は１００ｋΩ、コンデンサ７の値は０.１μＦ、矩形波の振幅は５Ｖp-p、周波数は１０Ｈｚとした。図３に示すように、リーク抵抗が小さくなるほど振幅が小さくなり、リークが悪化したことが検出可能である。図４に、この場合のリーク抵抗と振幅との関係を示す。図４に示すように、リーク抵抗が小さいほど振幅は小さくなる。   FIG. 3 shows the calculation result of how the output waveform changes depending on the resistance value of the leak resistor 9 in this leak detection circuit. The value of resistor 4 was 43 kΩ, the value of capacitor 3 was 2.2 μF, the value of resistor 6 was 100 kΩ, the value of capacitor 7 was 0.1 μF, the amplitude of the rectangular wave was 5 Vp-p, and the frequency was 10 Hz. As shown in FIG. 3, the smaller the leak resistance, the smaller the amplitude, and it can be detected that the leak has deteriorated. FIG. 4 shows the relationship between the leakage resistance and the amplitude in this case. As shown in FIG. 4, the smaller the leak resistance, the smaller the amplitude.

特許２９３３４９０号Japanese Patent No. 2933490

しかしながら、従来のリーク検出回路では、比較的小さいリーク抵抗の検出が困難である、という課題を有していた。例えば、ある車両のシステムではリーク抵抗が５ｋΩでシステムの動作を遮断するものもある。図４に示すように、リーク抵抗の値の低い５ｋΩの近傍では、リーク抵抗の変化に対する振幅の変化が小さく、この定数で精度よく検出することは困難である。   However, the conventional leak detection circuit has a problem that it is difficult to detect a relatively small leak resistance. For example, in some vehicle systems, the leakage resistance is 5 kΩ and the system operation is interrupted. As shown in FIG. 4, in the vicinity of 5 kΩ where the value of the leak resistance is low, the change in the amplitude with respect to the change in the leak resistance is small, and it is difficult to accurately detect with this constant.

一方、定数を変更することでこの問題を解決することは可能である。しかし、その場合、コストアップ及び実現性の点で問題が生じる。図５は定数を変更して振幅の変化を計算した例を示したものである。この例では、計算を簡単にするために矩形波ではなく正弦波を印加して計算しているが、矩形波でも正弦波でも応答特性は本質的に変わるものではなく傾向は同一である。図５に示すように、コンデンサ３を１０倍の２２μＦにした場合は低いリーク抵抗でもリーク抵抗の変化に対する振幅の変化は大きくなっている。しかしながら、コンデンサ３は高耐圧のものでなければならず、容量を大きくするのはコストアップ及び部品サイズの増大を招く。また、周波数を１０倍の１００Ｈｚとして、コンデンサ７の容量を１／１０とした場合でも同様の特性になっているが、マイクロコンピュータの処理速度を上げることになり、既存の車両制御用システムに組み込むことは困難となる。更に、コンデンサ７の容量を１／１０倍としたことでカットオフ周波数が高くなり、ノイズに弱くなることも懸念される。   On the other hand, it is possible to solve this problem by changing the constant. However, in that case, problems arise in terms of cost increase and feasibility. FIG. 5 shows an example in which the change in amplitude is calculated by changing the constant. In this example, the calculation is performed by applying a sine wave instead of a rectangular wave to simplify the calculation. However, the response characteristics are not essentially changed regardless of the rectangular wave or the sine wave, and the tendency is the same. As shown in FIG. 5, when the capacitor 3 is 10 times as large as 22 μF, the change in amplitude with respect to the change in leak resistance is large even with a low leak resistance. However, the capacitor 3 must have a high withstand voltage, and increasing the capacitance causes an increase in cost and an increase in component size. Further, even when the frequency is 10 times 100 Hz and the capacity of the capacitor 7 is 1/10, the same characteristics are obtained, but the processing speed of the microcomputer is increased, and it is incorporated into an existing vehicle control system. It becomes difficult. Furthermore, there is a concern that the cut-off frequency is increased and the noise is weakened by setting the capacitance of the capacitor 7 to 1/10.

本発明は上記事案に鑑み、測定周波数やコンデンサの容量も上げることなく、低いリーク抵抗の検出が可能なリーク検出装置を提供することを課題とする。   An object of the present invention is to provide a leak detection device capable of detecting a low leak resistance without increasing the measurement frequency and the capacitance of the capacitor.

上記課題を解決するために、本発明は、車体と電気的に絶縁された直流電源回路と前記車体に接地された車両電装回路とを有する電気自動車のリーク検出装置において、一定電圧振幅の矩形波を発生させる矩形波発生回路の出力を、コンデンサを介して前記直流電源と車体グラウンドとの間に引加し、前記コンデンサに流れる電流を測定することで前記車体と前記直流電源との間のリークを検出することを特徴とする。   In order to solve the above-mentioned problems, the present invention provides a rectangular wave having a constant voltage amplitude in a leak detection apparatus for an electric vehicle having a DC power supply circuit electrically insulated from the vehicle body and a vehicle electrical circuit grounded to the vehicle body. A leakage between the vehicle body and the DC power source is obtained by applying an output of a rectangular wave generating circuit that generates a current between the DC power source and the vehicle body ground via a capacitor and measuring a current flowing through the capacitor. Is detected.

本発明では、コンデンサに一定電圧振幅の矩形波を印加し、流れる電流を測定するので、低いリーク抵抗の検出が可能となる。図６にその計算例を示す。簡略化のため、正弦波の通電として流れる電流の変化を計算した。通電周波数は１０Ｈｚでコンデンサは背景技術欄で説明した従来のリーク検出回路と同じ２．２μＦ、交流印加電圧は５Ｖｒｍｓとした。図６に示すように、リーク抵抗が小さくなるほど通電電流は大きくなり、リーク抵抗が５ｋΩ程度でも、リーク抵抗の変化に対する振幅の変化は大きくなっている。リーク抵抗が１０ｋΩから５ｋΩまで変化した場合の振幅の変化を、従来のリーク検出装置と本発明のリーク検出装置とで比較してみると、従来のリーク検出装置では１０ｋΩの場合の８０％に変化したのに対し、本発明のリーク検出装置では１４２％に変化しており、本発明のリーク検出装置の方が低リーク抵抗の検出がしやすくなる。このため、本発明によれば、従来、測定周波数を高くするかコンデンサの容量を大きくするしか検出することができなかった低いリーク抵抗の検出が可能となる。   In the present invention, a rectangular wave having a constant voltage amplitude is applied to the capacitor and the flowing current is measured, so that a low leakage resistance can be detected. FIG. 6 shows an example of the calculation. For the sake of simplicity, the change in the current that flows as a sine wave was calculated. The energization frequency was 10 Hz, the capacitor was 2.2 μF, which was the same as the conventional leak detection circuit described in the background section, and the AC applied voltage was 5 Vrms. As shown in FIG. 6, the smaller the leak resistance is, the larger the energization current is, and even when the leak resistance is about 5 kΩ, the change in amplitude with respect to the change in leak resistance is large. When the change in amplitude when the leak resistance changes from 10 kΩ to 5 kΩ is compared between the conventional leak detection device and the leak detection device of the present invention, the conventional leak detection device changes to 80% in the case of 10 kΩ. On the other hand, the leak detection device of the present invention changes to 142%, and the leak detection device of the present invention can more easily detect the low leak resistance. For this reason, according to the present invention, it is possible to detect a low leakage resistance that could only be detected by increasing the measurement frequency or increasing the capacitance of the capacitor.

上述したように、本発明では一定電圧振幅の矩形波を発生させる矩形波発生回路の出力をコンデンサに通電し、かつ、コンデンサに流れる電流を検出する必要があるが、電流検出抵抗と演算増幅器を用いてフィードバックループを形成すれば、一定電圧振幅の矩形波をコンデンサに印加でき、かつ、電流検出用抵抗に発生する電圧を増幅して電圧出力として検出することが可能となる。   As described above, in the present invention, it is necessary to energize the capacitor with the output of the rectangular wave generating circuit that generates a rectangular wave having a constant voltage amplitude, and to detect the current flowing through the capacitor. If a feedback loop is formed by using a rectangular wave having a constant voltage amplitude, it is possible to amplify the voltage generated in the current detection resistor and detect it as a voltage output.

本発明によれば、一定電圧振幅の矩形波を発生させる矩形波発生回路の出力を、コンデンサを介して直流電源と車体グラウンドとの間に引加し、コンデンサに流れる電流を測定するため、測定周波数やコンデンサの容量も上げることなく、低いリーク抵抗の検出できる、という効果を得ることができる。   According to the present invention, the output of a rectangular wave generating circuit that generates a rectangular wave having a constant voltage amplitude is applied between a DC power source and a vehicle body ground via a capacitor, and the current flowing through the capacitor is measured. The effect that a low leak resistance can be detected without increasing the frequency and the capacitance of the capacitor can be obtained.

以下、本発明に係る電気自動車のリーク検出装置の実施の形態について説明する。   Embodiments of a leak detection apparatus for an electric vehicle according to the present invention will be described below.

電気自動車は、車体と電気的に絶縁された直流電源回路と、車体（シャーシグラウンド）に接地された図示しない車両電装回路を搭載している。図１に示すように、直流電源回路を構成し、複数の単電池を直列接続した高電圧の電池群１が、図示しないスイッチを介して負荷２に接続されている。負荷２には、電池群１により駆動される交流回路が含まれている。本実施形態のリーク検出装置２０はリーク検出回路を有しており、電池群１の＋端子側はリーク検出用コンデンサ３を介してリーク検出回路部に接続される。   The electric vehicle includes a DC power supply circuit that is electrically insulated from the vehicle body and a vehicle electrical circuit (not shown) that is grounded to the vehicle body (chassis ground). As shown in FIG. 1, a high-voltage battery group 1 that constitutes a DC power supply circuit and includes a plurality of unit cells connected in series is connected to a load 2 via a switch (not shown). The load 2 includes an AC circuit driven by the battery group 1. The leak detection device 20 of this embodiment has a leak detection circuit, and the positive terminal side of the battery group 1 is connected to the leak detection circuit unit via the leak detection capacitor 3.

リーク検出回路部は、マイコン５及び増幅器で構成されている。すなわち、マイコン５は一定電圧振幅の矩形波を出力する出力ポートを有しており、この出力ポートが演算増幅器１１の正相入力端子に接続されている。演算増幅器１１の出力端子は電流検出用抵抗１０の一端に接続されており、抵抗１０の他端は、他端が電池群１の＋端子側に接続されるコンデンサ３の一端に接続されていると共に、演算増幅器１１の逆相入力端子に接続されている。この演算増幅器１１は、正相入力端子と逆相入力端子との電圧が等しくなる動作をするため、コンデンサ３と抵抗１０との接続点には、マイコン５の出力ポートから出力された矩形波電圧と同一電圧が引加される。   The leak detection circuit unit includes a microcomputer 5 and an amplifier. That is, the microcomputer 5 has an output port that outputs a rectangular wave having a constant voltage amplitude, and this output port is connected to the positive phase input terminal of the operational amplifier 11. The output terminal of the operational amplifier 11 is connected to one end of the current detection resistor 10, and the other end of the resistor 10 is connected to one end of the capacitor 3 connected to the positive terminal side of the battery group 1. At the same time, it is connected to the reverse phase input terminal of the operational amplifier 11. Since the operational amplifier 11 operates so that the voltages at the positive phase input terminal and the negative phase input terminal are equal, the rectangular wave voltage output from the output port of the microcomputer 5 is connected to the connection point between the capacitor 3 and the resistor 10. The same voltage is applied.

抵抗１０は電流検出用の抵抗で、両端の電圧は抵抗１２〜１５と演算増幅器１６で構成される差動増幅器の入力に接続されている。すなわち、抵抗１０の一端には抵抗１３の一端が接続されており、抵抗１３の他端は、他端がシャーシグラウンドに接続された抵抗１４の一端に接続されており、抵抗１３の他端と抵抗１４の一端との接続点が演算増幅器１６の正相入力端子に接続されている。また、抵抗１０の他端には抵抗１２の一端が接続されており、抵抗１２の他端は、演算増幅器１６の逆相入力端子に接続されている。演算増幅器１６の出力端子、逆相入力端子間には抵抗１５が挿入されている。更に、演算増幅器１６の出力端子は、マイコン５のＡＤ入力に接続されている。なお、マイコン５はシャーシグラウンドに接続されている。   The resistor 10 is a resistor for current detection, and the voltage at both ends is connected to the input of a differential amplifier composed of resistors 12 to 15 and an operational amplifier 16. That is, one end of the resistor 13 is connected to one end of the resistor 10, and the other end of the resistor 13 is connected to one end of the resistor 14 whose other end is connected to the chassis ground. A connection point with one end of the resistor 14 is connected to the positive phase input terminal of the operational amplifier 16. One end of the resistor 12 is connected to the other end of the resistor 10, and the other end of the resistor 12 is connected to the negative phase input terminal of the operational amplifier 16. A resistor 15 is inserted between the output terminal and the negative phase input terminal of the operational amplifier 16. Further, the output terminal of the operational amplifier 16 is connected to the AD input of the microcomputer 5. The microcomputer 5 is connected to the chassis ground.

本実施形態のリーク検出装置２０では、マイコン５の出力ポートから一定電圧振幅の矩形波を演算増幅器１１の正相入力端子とシャーシグラウンドとの間に出力し、演算増幅器１６及び抵抗１２〜１５で構成される差動増幅器で抵抗１０の両端電圧を測定することで、コンデンサ３に流れる電流を測定する。より具体的には、マイコン５は、ＡＤコンバータ（このＡＤコンバータの入力が上述したＡＤ入力である。）を内蔵しており、マイコン５はデジタル値として抵抗１０の両端電圧（応答波形）、すなわち、コンデンサ３に流れる電流を取り込み、取り込んだ抵抗１０の両端電圧の振幅を測定することでリーク検出を行う。   In the leak detection apparatus 20 of the present embodiment, a rectangular wave having a constant voltage amplitude is output from the output port of the microcomputer 5 between the positive phase input terminal of the operational amplifier 11 and the chassis ground, and the operational amplifier 16 and the resistors 12 to 15 are used. The current flowing through the capacitor 3 is measured by measuring the voltage across the resistor 10 with the differential amplifier configured. More specifically, the microcomputer 5 incorporates an AD converter (the input of the AD converter is the above-described AD input), and the microcomputer 5 has a voltage across the resistor 10 (response waveform) as a digital value, that is, The leak detection is performed by taking in the current flowing through the capacitor 3 and measuring the amplitude of the voltage across the resistor 10 taken in.

次に、本実施形態のリーク検出装置２０に従って作製した実施例のリーク検出回路について説明する。比較のために背景技術欄で説明した図２のリーク検出回路（比較例）についても併記する。   Next, the leak detection circuit of the example produced according to the leak detection apparatus 20 of this embodiment is demonstrated. For comparison, the leak detection circuit (comparative example) in FIG.

図７に、実施例のリーク検出回路について、実際にリーク抵抗９を接続しながらＡＤ入力波形の測定を行った結果を示す。矩形波の出力周波数を１０Ｈｚ、振幅を５Ｖp-p、コンデンサ３の容量を２．２μＦ、抵抗１０の値を４．７ｋΩとした。図７に示すように、リーク抵抗が１ＭΩ、１００ｋΩでは振幅の変化が小さいが、１０ｋΩ程度から振幅が大きくなり、１ｋΩでは５Ｖ以上の振幅が得られている。図８にリーク抵抗と振幅の関係を示す。図８に示すようにリーク抵抗が小さいほど振幅が大きいのが実施例（実施形態）のリーク検出回路の特徴である。また、図８には電流検出抵抗が４７ｋΩの場合の特性線も示している。電流検出抵抗値を大きくすることで、より高いリーク抵抗で振幅の変化が大きくなることも実施例（実施形態）のリーク検出回路の特徴であり、コンデンサの値及び矩形波の周波数を変更せずに、希望するリーク抵抗検出値に合わせた設計を行うことができる。   FIG. 7 shows the result of measuring the AD input waveform while actually connecting the leak resistor 9 to the leak detection circuit of the example. The output frequency of the rectangular wave was 10 Hz, the amplitude was 5 Vp-p, the capacitance of the capacitor 3 was 2.2 μF, and the value of the resistor 10 was 4.7 kΩ. As shown in FIG. 7, the change in amplitude is small when the leak resistance is 1 MΩ and 100 kΩ, but the amplitude is increased from about 10 kΩ, and an amplitude of 5 V or more is obtained at 1 kΩ. FIG. 8 shows the relationship between leakage resistance and amplitude. As shown in FIG. 8, the smaller the leak resistance, the larger the amplitude, which is a feature of the leak detection circuit of the embodiment (embodiment). FIG. 8 also shows a characteristic line when the current detection resistance is 47 kΩ. It is also a feature of the leak detection circuit of the embodiment (embodiment) that the amplitude change becomes larger with a higher leak resistance by increasing the current detection resistance value, without changing the value of the capacitor and the frequency of the rectangular wave. In addition, it is possible to design in accordance with a desired leak resistance detection value.

図９は、比較例（従来方式）のリーク検出回路と実施例のリーク検出回路とを比較した特性線図である。リーク抵抗の変化に伴う振幅の変化を比較するために、縦軸は振幅の変化率で示している。比較例のリーク検出回路では、リーク抵抗が１ＭΩの場合を１、実施例のリーク検出回路では電流検出抵抗が４．７ＫΩの場合がリーク抵抗１ｋΩで１、抵抗１０が４７ｋΩの場合がリーク抵抗１０ｋΩの場合に１としている。図９に示すように、実施例のリーク検出回路ではリーク抵抗が小さい場合に振幅の変化が大きく、かつ、抵抗１０の値を変更するだけで望みのリーク抵抗を検出しやすくすることが可能である。   FIG. 9 is a characteristic diagram comparing the leak detection circuit of the comparative example (conventional method) and the leak detection circuit of the embodiment. In order to compare the change in amplitude accompanying the change in leak resistance, the vertical axis represents the rate of change in amplitude. In the leak detection circuit of the comparative example, 1 is used when the leak resistance is 1 MΩ, and in the leak detection circuit of the embodiment, when the current detection resistance is 4.7 KΩ, the leak resistance is 1 kΩ, and when the resistance 10 is 47 kΩ, the leak resistance is 10 kΩ. In this case, it is set to 1. As shown in FIG. 9, in the leak detection circuit of the embodiment, the change in amplitude is large when the leak resistance is small, and it is possible to easily detect the desired leak resistance simply by changing the value of the resistor 10. is there.

以上のように、本実施形態のリーク検出装置２０では、マイコン５の出力ポートから一定電圧振幅の矩形波を、コンデンサ３を介して電池群１に接続し、コンデンサ３に流れる電流を測定する。コンデンサ３に流れる電流を測定するために、マイコン５の出力ポートからの出力が演算増幅器１１の正相入力に接続されており、演算増幅器１１の出力は電流検出用抵抗１１を介してコンデンサ３に接続されており、かつ、コンデンサ３と電流検出用抵抗１１との接続点が演算増幅器１１の逆相入力に接続されており、更に、電流検出用抵抗１１の両端の電圧を演算増幅器１６及び抵抗１２〜１５で構成される差動増幅器の入力とし、該差動増幅器の出力電圧を検出する構成を採っている。このため、一定振幅の矩形波電圧をコンデンサ３に印加でき、かつ、電流検出用抵抗１１に発生する電圧を増幅して電圧出力として検出が可能となり、測定周波数やコンデンサ３の容量も上げることなく、低いリーク抵抗の検出できる。しかも、容量の小さいコンデンサ、演算増幅器、抵抗の比較的簡単な回路でリーク検出装置が構成できる点で工業的価値が大きい。   As described above, in the leak detection device 20 of the present embodiment, a rectangular wave having a constant voltage amplitude is connected from the output port of the microcomputer 5 to the battery group 1 via the capacitor 3, and the current flowing through the capacitor 3 is measured. In order to measure the current flowing through the capacitor 3, the output from the output port of the microcomputer 5 is connected to the positive phase input of the operational amplifier 11, and the output of the operational amplifier 11 is connected to the capacitor 3 via the current detection resistor 11. The connection point between the capacitor 3 and the current detection resistor 11 is connected to the negative phase input of the operational amplifier 11, and the voltage across the current detection resistor 11 is connected to the operational amplifier 16 and the resistor. The differential amplifier composed of 12 to 15 is used as the input and the output voltage of the differential amplifier is detected. For this reason, a rectangular wave voltage having a constant amplitude can be applied to the capacitor 3, and the voltage generated in the current detection resistor 11 can be amplified and detected as a voltage output without increasing the measurement frequency and the capacitance of the capacitor 3. , Low leakage resistance can be detected. Moreover, the industrial value is great in that the leak detection device can be configured with a relatively simple circuit having a small capacity capacitor, operational amplifier, and resistor.

なお、本実施形態では、矩形波発生回路をマイコン５内に内蔵し、マイコン５の出力ポートから演算増幅器１１の正相入力端子とシャーシグラウンドとの間に引加する例を示したが、本発明はこれに制限されず、マイコン５の外に矩形波発生回路を設けるようにしてもよい。   In the present embodiment, a rectangular wave generation circuit is built in the microcomputer 5 and is applied from the output port of the microcomputer 5 between the positive phase input terminal of the operational amplifier 11 and the chassis ground. The invention is not limited to this, and a rectangular wave generating circuit may be provided outside the microcomputer 5.

本発明は測定周波数やコンデンサの容量も上げることなく、低いリーク抵抗の検出が可能なリーク検出装置を提供することを目的とするため、リーク検出装置の製造、販売に寄与するので、産業上の利用可能性を有する。   An object of the present invention is to provide a leak detection device capable of detecting a low leak resistance without increasing the measurement frequency and the capacitance of the capacitor. Has availability.

本発明が適用可能な実施形態のリーク検出装置のリーク検出回路の回路図である。1 is a circuit diagram of a leak detection circuit of a leak detection apparatus according to an embodiment to which the present invention is applicable. 従来のリーク検出装置のリーク検出回路の回路図である。It is a circuit diagram of the leak detection circuit of the conventional leak detection apparatus. 従来のリーク検出回路での電圧応答波形を示す特性線図である。It is a characteristic diagram which shows the voltage response waveform in the conventional leak detection circuit. 従来のリーク検出回路でのリーク抵抗と応答波形の振幅の関係を示す特性線図である。It is a characteristic diagram which shows the relationship between the leak resistance in the conventional leak detection circuit, and the amplitude of a response waveform. 従来のリーク検出回路で、定数を変えた場合のリーク抵抗と応答波形の振幅の関係を示す特性線図である。It is a characteristic line figure which shows the relationship between the leak resistance at the time of changing a constant in the conventional leak detection circuit, and the amplitude of a response waveform. 実施形態のリーク検出回路でのリーク抵抗とコンデンサの通電電流の関係を示す特性線図である。It is a characteristic diagram which shows the relationship between the leakage resistance in the leakage detection circuit of embodiment, and the energization current of a capacitor | condenser. 実施形態のリーク検出回路でのリーク抵抗を変えた場合の応答波形を示す特性線図である。It is a characteristic diagram which shows the response waveform at the time of changing the leak resistance in the leak detection circuit of embodiment. 実施形態のリーク検出回路でのリーク抵抗と応答波形の振幅の関係を示す特性線図である。It is a characteristic diagram which shows the relationship between the leak resistance in the leak detection circuit of embodiment, and the amplitude of a response waveform. 実施例のリーク検出回路と比較例のリーク検出回路での、リーク抵抗と応答波形の振幅の変化を示す特性線図である。It is a characteristic diagram which shows the change of the amplitude of a leak resistance and a response waveform in the leak detection circuit of an Example, and the leak detection circuit of a comparative example.

符号の説明Explanation of symbols

１ 電池群（直流電源回路）
３ リーク検出用コンデンサ（コンデンサ）
５ マイコン（矩形波発生回路）
１０ 電流検出用抵抗
１１ 演算増幅器
１６ 演算増幅器（差動増幅器の一部）
２０ リーク検出装置 1 Battery group (DC power supply circuit)
3 Leakage detection capacitor (capacitor)
5 Microcomputer (rectangular wave generator)
10 current detection resistor 11 operational amplifier 16 operational amplifier (part of differential amplifier)
20 Leak detection device

Claims (3)

車体と電気的に絶縁された直流電源回路と前記車体に接地された車両電装回路とを有する電気自動車のリーク検出装置において、一定電圧振幅の矩形波を発生させる矩形波発生回路の出力を、コンデンサを介して前記直流電源と車体グラウンドとの間に引加し、前記コンデンサに流れる電流を測定することで前記車体と前記直流電源との間のリークを検出することを特徴とする電気自動車のリーク検出装置。   In a leak detection apparatus for an electric vehicle having a DC power supply circuit electrically insulated from a vehicle body and a vehicle electrical circuit grounded to the vehicle body, an output of a rectangular wave generation circuit that generates a rectangular wave having a constant voltage amplitude is provided as a capacitor. Leakage of an electric vehicle, wherein the leak between the DC power source and the DC power source is detected by applying a current between the DC power source and the vehicle body ground via an electric current and measuring a current flowing through the capacitor Detection device. 前記矩形波発生回路の出力が演算増幅器の正相入力に接続されており、前記演算増幅器の出力は電流検出用抵抗を介して前記コンデンサに接続されており、かつ、前記コンデンサと前記電流検出用抵抗との接続点が前記演算増幅器の逆相入力に接続されており、前記電流検出用抵抗の両端電圧を検出することで前記コンデンサに流れる電流を測定することを特徴とする請求項１に記載の電気自動車のリーク検出装置。   The output of the rectangular wave generation circuit is connected to the positive phase input of an operational amplifier, the output of the operational amplifier is connected to the capacitor via a current detection resistor, and the capacitor and the current detection output The connection point with the resistor is connected to the negative phase input of the operational amplifier, and the current flowing through the capacitor is measured by detecting the voltage across the current detection resistor. Electric vehicle leak detection device. 前記電流検出用抵抗の両端の電圧を差動増幅器の入力とし、該差動増幅器の出力電圧を検出することで前記コンデンサに流れる電流を測定することを特徴とする請求項２に記載の電気自動車のリーク検出装置。   The electric vehicle according to claim 2, wherein a voltage flowing across the capacitor is measured by using a voltage across the current detection resistor as an input of a differential amplifier and detecting an output voltage of the differential amplifier. Leak detection device.
JP2005273503A 2005-09-21 2005-09-21 Leak detector for electric car Withdrawn JP2007089277A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011154028A (en) * 2010-01-26 2011-08-11 Maxim Integrated Products Inc Isolation monitoring system and method utilizing variable emulated inductance
CN110703048A (en) * 2019-09-05 2020-01-17 安徽力高新能源技术有限公司 Self-adaptive method for insulation monitoring time of electric automobile
RU213458U1 (en) * 2022-02-28 2022-09-13 Дериземля Дмитрий Анатольевич HIGH VOLTAGE TRACTION BATTERY UNIT
US20220357408A1 (en) * 2019-06-28 2022-11-10 Sanyo Electric Co., Ltd. Leakage detection device and power system for vehicle

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011154028A (en) * 2010-01-26 2011-08-11 Maxim Integrated Products Inc Isolation monitoring system and method utilizing variable emulated inductance
US20220357408A1 (en) * 2019-06-28 2022-11-10 Sanyo Electric Co., Ltd. Leakage detection device and power system for vehicle
CN110703048A (en) * 2019-09-05 2020-01-17 安徽力高新能源技术有限公司 Self-adaptive method for insulation monitoring time of electric automobile
RU213458U1 (en) * 2022-02-28 2022-09-13 Дериземля Дмитрий Анатольевич HIGH VOLTAGE TRACTION BATTERY UNIT

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