JP4003137B2 - Ground fault detection device - Google Patents

Ground fault detection device Download PDF

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JP4003137B2
JP4003137B2 JP2004044577A JP2004044577A JP4003137B2 JP 4003137 B2 JP4003137 B2 JP 4003137B2 JP 2004044577 A JP2004044577 A JP 2004044577A JP 2004044577 A JP2004044577 A JP 2004044577A JP 4003137 B2 JP4003137 B2 JP 4003137B2
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ground fault
fault detection
voltage
coupling capacitor
circuit
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JP2005233822A (en
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工 清水
弘幸 矢野
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Denso Corp
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Description

本発明は、車体に対して絶縁される直流高電圧電源の地絡検出装置に関する。   The present invention relates to a ground fault detection device for a DC high-voltage power source insulated from a vehicle body.

電気自動車に搭載されるモータ駆動装置は高電圧のバッテリを使用している。そのため、安全性の観点から、そのバッテリとその高電圧が印加されるインバータ回路及びモータ巻線は一般に車体に対して絶縁されている。さらに、それらが車体と電気的に接触する状態、いわゆる地絡を検出するための地絡検出装置が設けられている。   A motor drive device mounted on an electric vehicle uses a high-voltage battery. Therefore, from the viewpoint of safety, the battery, the inverter circuit to which the high voltage is applied, and the motor winding are generally insulated from the vehicle body. Furthermore, a ground fault detection device for detecting a state in which they are in electrical contact with the vehicle body, that is, a so-called ground fault is provided.

この地絡検出装置として、例えば、車体に対して絶縁された高電圧のバッテリ群と、発振回路と、検出部とを備えた地絡検出回路が特開平８−７０５０３号公報に開示されている。この地絡検出回路の発振回路は、一定周波数の矩形波を発生する発振器と、インピーダンス変換器と、インピーダンス変換器の後段に接続され矩形波パルスを検出する検出抵抗とから構成されている。発振回路の出力は、検出部に接続されるとともにカップリングコンデンサを介してバッテリ群のプラス母線に接続される。そのため、発振回路と検出部とは高電圧のバッテリ群と直流的に絶縁される。例えば、バッテリ群のマイナス母線と車体との間で地絡が発生した場合、発振回路から出力される矩形波パルスは、検出抵抗と地絡抵抗とで分圧されるため検出抵抗の出力端における波高値が低下する。この矩形波パルスの波高値の変化を検出部で判定基準と比較することにより、地絡検出回路は地絡を検出することができる。また、発振回路や検出部は、高電圧のバッテリ群と直流的に絶縁されているため、車体に対して接地された低電圧のバッテリで作動する回路でそれらの信号を処理することが可能となり、回路構成を簡素化することができる。
特開平８−７０５０３号公報 As this ground fault detection device, for example, a ground fault detection circuit including a high-voltage battery group insulated from a vehicle body, an oscillation circuit, and a detection unit is disclosed in Japanese Patent Laid-Open No. 8-70503. . The oscillation circuit of the ground fault detection circuit includes an oscillator that generates a rectangular wave having a constant frequency, an impedance converter, and a detection resistor that is connected to a subsequent stage of the impedance converter and detects a rectangular wave pulse. The output of the oscillation circuit is connected to the detection unit and to the positive bus of the battery group via a coupling capacitor. Therefore, the oscillation circuit and the detection unit are galvanically isolated from the high voltage battery group. For example, when a ground fault occurs between the negative bus of the battery group and the vehicle body, the rectangular wave pulse output from the oscillation circuit is divided by the detection resistance and the ground fault resistance, so that at the output end of the detection resistance The peak value decreases. The ground fault detection circuit can detect the ground fault by comparing the change in the peak value of the rectangular wave pulse with the determination criterion by the detection unit. In addition, since the oscillation circuit and the detection unit are galvanically isolated from the high voltage battery group, it is possible to process these signals with a circuit that operates with a low voltage battery grounded to the vehicle body. The circuit configuration can be simplified.
JP-A-8-70503

しかし、このような地絡検出回路において、検出抵抗からカップリングコンデンサを経てバッテリ群に至る経路で断線が発生すると、たとえバッテリ群のマイナス母線と車体との間で地絡が発生していても検出抵抗の出力端における矩形波パルスの波高値は全く変化しない。そのため、地絡を検出することができない。   However, in such a ground fault detection circuit, if a disconnection occurs in the path from the detection resistor to the battery group via the coupling capacitor, even if a ground fault occurs between the negative bus of the battery group and the vehicle body The peak value of the rectangular pulse at the output end of the detection resistor does not change at all. Therefore, a ground fault cannot be detected.

本発明は、このような事情に鑑みてなされたものであり、直流電源又はそれに接続される負荷の少なくともいずれかで発生する地絡を検出する地絡検出装置において、カップリングコンデンサを含む地絡検出手段から直流電源に至る経路における断線を確実に検出できる地絡検出装置を提供することを目的とする。   The present invention has been made in view of such circumstances, and in a ground fault detection device that detects a ground fault occurring in at least one of a DC power supply and a load connected thereto, a ground fault including a coupling capacitor is provided. An object of the present invention is to provide a ground fault detection device capable of reliably detecting a disconnection in a path from a detection means to a DC power source.

そこで、本発明者は、この課題を解決すべく鋭意研究し試行錯誤を重ねた結果、断続手段が直流電源を負荷に接続したときの地絡検出手段とカップリングコンデンサとの接続点の電圧の大きさから、カップリングコンデンサを含む地絡検出手段から直流電源に至るの経路における断線を判定できることを思いつき、本発明を完成するに至った。   Therefore, as a result of intensive research and trial and error in order to solve this problem, the present inventor has found that the voltage at the connection point between the ground fault detection means and the coupling capacitor when the intermittent means connects the DC power source to the load. From the size, the inventors came up with the idea that it is possible to determine the disconnection in the path from the ground fault detection means including the coupling capacitor to the DC power supply, and the present invention has been completed.

すなわち、請求項１に記載の地絡検出装置は、車体に対して絶縁される直流電源と、前記車体に対して絶縁されるとともに前記直流電源から電力を供給されることにより作動する負荷と、前記直流電源と前記負荷とを接続又は遮断する断続手段と、前記車体に接地されるとともに前記断続手段が前記直流電源を前記負荷に接続した後に前記直流電源又は前記負荷の少なくともいずれかの地絡を検出する地絡検出手段と、前記地絡検出手段と前記直流電源とを接続するカップリングコンデンサとを備えた地絡検出装置において、さらに、前記断続手段が前記直流電源を前記負荷に接続した後に前記地絡検出手段と前記カップリングコンデンサとの接続点の電圧の大きさを所定の断線判定値と比較することにより前記カップリングコンデンサを含む前記地絡検出手段から前記直流電源に至る経路における断線を検出する断線検出手段を有することを特徴とする。   That is, the ground fault detection device according to claim 1 is a DC power source that is insulated from the vehicle body, a load that is insulated from the vehicle body and is operated by being supplied with electric power from the DC power source, Intermittent means for connecting or disconnecting the DC power supply and the load, and a ground fault of at least one of the DC power supply or the load after being grounded to the vehicle body and the intermittent means connecting the DC power supply to the load In a ground fault detection apparatus comprising a ground fault detection means for detecting the ground fault, and a coupling capacitor for connecting the ground fault detection means and the DC power source, the intermittent means further connects the DC power source to the load. The coupling capacitor is included by comparing the magnitude of the voltage at the connection point between the ground fault detection means and the coupling capacitor with a predetermined disconnection determination value later. Characterized in that it has a disconnection detecting means for detecting a disconnection in the path to the DC power source from the ground fault detection means.

請求項２に記載の地絡検出装置は、請求項１に記載の地絡検出装置において、さらに、前記地絡検出手段は、前記接続点に接続されるとともに前記断続手段が前記直流電源を前記負荷に接続した後に前記接続点の電圧の大きさを所定の第１地絡判定値と比較することにより、前記断続手段が前記直流電源を前記負荷に接続する前に発生した前記地絡を検出する第１地絡判定手段を有することを特徴とする。   The ground fault detection device according to claim 2 is the ground fault detection device according to claim 1, wherein the ground fault detection means is connected to the connection point and the intermittent means supplies the DC power source. By comparing the voltage level at the connection point with a predetermined first ground fault judgment value after connecting to the load, the interrupting means detects the ground fault generated before connecting the DC power supply to the load. It has the 1st ground fault determination means to do.

請求項３に記載の地絡検出装置は、請求項１又は２に記載の地絡検出装置において、さらに、前記地絡検出手段は、交流信号を発生する交流信号発生手段と、一端が前記交流信号発生手段に接続されるとともに他端が前記カップリングコンデンサに接続される地絡検出抵抗と、前記接続点に接続されるとともに前記断続手段が前記直流電源を前記負荷に接続してから所定の時間経過後に前記接続点の電圧の大きさを所定の第２地絡判定値と比較することにより前記地絡を判定する第２地絡判定手段とを有することを特徴とする。   The ground fault detection device according to claim 3 is the ground fault detection device according to claim 1 or 2, wherein the ground fault detection means further includes an AC signal generation means for generating an AC signal, and one end of the AC fault detection apparatus. A ground fault detecting resistor connected to the signal generating means and having the other end connected to the coupling capacitor; and connected to the connection point and connected to the load by the intermittent means And a second ground fault determination means for determining the ground fault by comparing the voltage level of the connection point with a predetermined second ground fault determination value after a lapse of time.

なお、本明細書でいう第１及び第２地絡判定値、第１及び第２地絡判定手段とは、それぞれの地絡判定値及び地絡判定手段を区別するために便宜的に導入したものである。   In addition, the 1st and 2nd ground fault judgment value and the 1st and 2nd ground fault judgment means in this specification were introduced for convenience in order to distinguish each ground fault judgment value and ground fault judgment means. Is.

請求項１に記載の地絡検出装置によれば、断続手段が直流電源を負荷に接続した後に、
断線検出手段で地絡検出手段とカップリングコンデンサとの接続点の電圧の大きさを所定の断線判定値と比較することができる。ここで、断続手段が直流電源を負荷に接続すると、直流電源の出力電圧は出力端と車体との間の絶縁抵抗により分圧されるため、直流電源の出力端の電圧は大きく変化する。これにより、カップリングコンデンサを含む地絡検出手段から直流電源に至る経路において断線が発生していない場合、地絡検出手段とカップリングコンデンサとの接続点の電圧も大きく変化する。そして、地絡検出回路の内部抵抗とカップリングコンデンサの容量とで決まる時定数に基づいて指数関数的に収束する。一方、カップリングコンデンサを含む地絡検出手段から直流電源に至る経路において断線が発生している場合、地絡検出手段とカップリングコンデンサとの接続点の電圧は変化しない。従って、地絡検出手段とカップリングコンデンサとの接続点の電圧の大きさを所定の断線判定値と比較することにより、カップリングコンデンサを含む地絡検出手段から直流電源に至る経路における断線を検出することができる。 According to the ground fault detection device of claim 1, after the intermittent means connects the DC power supply to the load,
The disconnection detection means can compare the voltage level at the connection point between the ground fault detection means and the coupling capacitor with a predetermined disconnection determination value. Here, when the interrupting means connects the DC power supply to the load, the output voltage of the DC power supply is divided by the insulation resistance between the output end and the vehicle body, so that the voltage at the output end of the DC power supply changes greatly. As a result, when no disconnection occurs in the path from the ground fault detection means including the coupling capacitor to the DC power supply, the voltage at the connection point between the ground fault detection means and the coupling capacitor also greatly changes. Then, it converges exponentially based on a time constant determined by the internal resistance of the ground fault detection circuit and the capacitance of the coupling capacitor. On the other hand, when a disconnection occurs in the path from the ground fault detection means including the coupling capacitor to the DC power supply, the voltage at the connection point between the ground fault detection means and the coupling capacitor does not change. Therefore, disconnection in the path from the ground fault detection means including the coupling capacitor to the DC power source is detected by comparing the voltage level at the connection point between the ground fault detection means and the coupling capacitor with a predetermined disconnection judgment value. can do.

請求項２に記載の地絡検出装置によれば、断続手段が直流電源を負荷に接続した後に、
第１地絡判定手段で地絡検出手段とカップリングコンデンサとの接続点の電圧の大きさを
所定の第１地絡判定値と比較することができる。ところで、断続手段が直流電源を負荷に接続する前に直流電源又は負荷の少なくともいずれかで地絡が発生していた場合、断続手段が直流電源を負荷に接続すると、直流電源の出力電圧は出力端と車体との間の絶縁抵抗と地絡抵抗とにより分圧される。そのため、地絡が発生していない場合に比べ、直流電源の出力端の電圧の変化の仕方が異なる。例えば、地絡している側に接続されている直流電源の出力端の電圧はほとんど変化しない。これに対し、地絡していない側に接続されている直流電源の出力端の電圧は、地絡が全く発生していない場合に比べさらに大きく変化する。これにより、断続手段が直流電源を負荷に接続する前に直流電源又は負荷の少なくともいずれかで地絡が発生していた場合、地絡検出手段とカップリングコンデンサとの接続点の電圧も直流電源の出力端と同じ様に変化する。従って、地絡検出手段とカップリングコンデンサとの接続点の電圧の大きさを所定の断線判定値及び所定の第１地絡判定値と比較することにより、直流電源又は負荷の少なくともいずれかの地絡を断線又は地絡として検出することができる。 According to the ground fault detection apparatus of claim 2, after the intermittent means connects the DC power supply to the load,
The magnitude of the voltage at the connection point between the ground fault detection means and the coupling capacitor can be compared with a predetermined first ground fault judgment value by the first ground fault judgment means. By the way, if a ground fault occurs in at least one of the DC power supply and the load before the interrupting means connects the DC power supply to the load, the output voltage of the DC power supply is output when the interrupting means connects the DC power supply to the load. The voltage is divided by the insulation resistance between the end and the vehicle body and the ground fault resistance. Therefore, the method of changing the voltage at the output terminal of the DC power supply is different from that in the case where no ground fault has occurred. For example, the voltage at the output terminal of the DC power source connected to the ground fault side hardly changes. On the other hand, the voltage at the output terminal of the DC power source connected to the non-ground fault side changes more greatly than when no ground fault occurs. As a result, if a ground fault has occurred in at least one of the DC power supply and the load before the intermittent means connects the DC power supply to the load, the voltage at the connection point between the ground fault detection means and the coupling capacitor is also the DC power supply. It changes in the same way as the output terminal. Therefore, by comparing the magnitude of the voltage at the connection point between the ground fault detection means and the coupling capacitor with the predetermined disconnection judgment value and the predetermined first ground fault judgment value, at least one of the ground of the DC power supply or the load is obtained. A fault can be detected as a break or a ground fault.

請求項３に記載の地絡検出装置によれば、断続手段が直流電源を負荷に接続してから所定の時間経過後に、第２地絡判定手段で地絡検出手段とカップリングコンデンサとの接続点の電圧の大きさを所定の第２地絡判定値と比較することができる。ところで、直流電源又は負荷の少なくともいずれかで地絡が発生した場合、交流信号発生手段から出力される出力信号はカップリングコンデンサを介して地絡検出抵抗と地絡抵抗とにより分圧される。この地絡抵抗の抵抗値は非常に小さいため地絡検出手段とカップリングコンデンサとの接続点における交流信号の波高値は低下する。しかし、断続手段が直流電源を負荷に接続すると、前述したように、地絡検出手段とカップリングコンデンサとの接続点の電圧は大きく変化してから収束する。従って、断続手段が直流電源を負荷に接続してから所定の時間経過後に地絡検出手段とカップリングコンデンサとの接続点の電圧の大きさを所定の第２地絡判定値と比較することにより、直流電源又は負荷の少なくともいずれかの地絡を検出することができる。   According to the ground fault detection device of claim 3, the second ground fault determination means connects the ground fault detection means and the coupling capacitor after a predetermined time has elapsed since the intermittent means connected the DC power supply to the load. The magnitude of the voltage at the point can be compared with a predetermined second ground fault determination value. By the way, when a ground fault occurs in at least one of the DC power supply and the load, the output signal output from the AC signal generating means is divided by the ground fault detection resistance and the ground fault resistance via the coupling capacitor. Since the resistance value of the ground fault resistance is very small, the peak value of the AC signal at the connection point between the ground fault detection means and the coupling capacitor is lowered. However, when the intermittent means connects the DC power supply to the load, as described above, the voltage at the connection point between the ground fault detecting means and the coupling capacitor is largely changed and then converges. Therefore, by comparing the magnitude of the voltage at the connection point between the ground fault detection means and the coupling capacitor with a predetermined second ground fault judgment value after a predetermined time has elapsed since the intermittent means connected the DC power supply to the load. In addition, it is possible to detect a ground fault of at least one of the DC power supply and the load.

本実施形態は、地絡検出装置を電気自動車のモータ駆動装置に適用した例を示す。本実施形態における地絡検出装置の回路図を図１に、さまざまな条件における地絡検出回路とカップリングコンデンサとの接続点の電圧波形を図２〜図５に示す。   This embodiment shows the example which applied the ground fault detection apparatus to the motor drive device of the electric vehicle. FIG. 1 shows a circuit diagram of the ground fault detection apparatus according to this embodiment, and FIGS. 2 to 5 show voltage waveforms at the connection points of the ground fault detection circuit and the coupling capacitor under various conditions.

まず、図１を参照して具体的構成について説明する。図１に示すように、地絡検出装置１は、高電圧バッテリ２（直流電源）と、インバータ回路３（負荷）と、交流モータ４（負荷）と、システムメインリレー５（断続手段）と、地絡検出回路６（地絡検出手段）と、カップリングコンデンサ７と、断線検出回路８（断線検出手段）とを備えている。   First, a specific configuration will be described with reference to FIG. As shown in FIG. 1, the ground fault detection device 1 includes a high voltage battery 2 (DC power supply), an inverter circuit 3 (load), an AC motor 4 (load), a system main relay 5 (intermittent means), A ground fault detection circuit 6 (ground fault detection means), a coupling capacitor 7, and a disconnection detection circuit 8 (disconnection detection means) are provided.

高電圧バッテリ２は、複数の電池モジュール２ａを直列接続して構成される、例えば、
出力電圧３００Ｖの組電池である。この高圧バッテリ２は車体に対して絶縁されており、高圧バッテリ２の正極側出力端２ｂ及び負極側出力端２ｃはシステムメインリレー５にそれぞれ接続されている。 The high voltage battery 2 is configured by connecting a plurality of battery modules 2a in series, for example,
It is an assembled battery with an output voltage of 300V. The high voltage battery 2 is insulated from the vehicle body, and the positive output terminal 2b and the negative output terminal 2c of the high voltage battery 2 are connected to the system main relay 5, respectively.

インバータ回路３は、コレクタ−エミッタ間に寄生ダイオードを有する６つのトランジスタ３ａ〜３ｆを３相ブリッジ接続して構成されている。このインバータ回路３の上側の３つのトランジスタ３ａ〜３ｃのコレクタは共通接続されて正極側入力端３ｇを構成し、下側の３つのトランジスタ３ｄ〜３ｆのエミッタは共通接続されて負極側入力端３ｈを構成している。インバータ回路３の正極側入力端３ｇ及び負極側入力端３ｈは、高抵抗で抵抗値の等しい２つのコモン電圧制御用抵抗３ｉ、３ｊを介してそれぞれ車体に接地されている。さらに、インバータ回路３の３相出力端子ＴＵ、ＴＶ、ＴＷは交流モータ４に接続されている。   The inverter circuit 3 is configured by connecting six transistors 3a to 3f having a parasitic diode between a collector and an emitter in a three-phase bridge connection. The collectors of the upper three transistors 3a to 3c of the inverter circuit 3 are commonly connected to constitute a positive input terminal 3g, and the emitters of the lower three transistors 3d to 3f are commonly connected to be connected to a negative input terminal 3h. Is configured. The positive input terminal 3g and the negative input terminal 3h of the inverter circuit 3 are grounded to the vehicle body via two common voltage control resistors 3i and 3j having a high resistance and an equal resistance value. Further, the three-phase output terminals TU, TV, TW of the inverter circuit 3 are connected to the AC motor 4.

交流モータ４は、複数のマグネットが配設されたロータと、モータ巻線４ａが券回されたステータとから構成されている。モータ巻線４ａは３つのコイルから構成されており、３つのコイルのそれぞれの一端は共通接続され、他端はインバータ回路３の３相出力端ＴＵ、ＴＶ、ＴＷにそれぞれ接続されている。   The AC motor 4 includes a rotor in which a plurality of magnets are disposed and a stator in which the motor winding 4a is wound. The motor winding 4a is composed of three coils, and one end of each of the three coils is connected in common, and the other end is connected to the three-phase output terminals TU, TV, TW of the inverter circuit 3, respectively.

システムメインリレー５は、２つのａ接点を有するメカニカルリレーで構成されており、高電圧バッテリ２とインバータ回路３との間に接続されている。そして、イグニッションスイッチ（図略）がオンされると、システムメインリレー５は、
高電圧バッテリ２の正極側出力端２ｂ及び負極側出力端２ｃをインバータ回路３の正極側入力端３ｇ及び負極側入力端３ｈにそれぞれ接続する。これにより、高電圧バッテリ２からインバータ回路３に直流電力が供給され、インバータ回路３はこの直流電力を交流電力に変換し交流モータ４に供給することで、交流モータ４はトルクを発生する。また、イグニッションスイッチがオフされると、システムメインリレー５は高電圧バッテリ２をインバータ回路３から遮断する。 The system main relay 5 is constituted by a mechanical relay having two a contacts, and is connected between the high voltage battery 2 and the inverter circuit 3. When the ignition switch (not shown) is turned on, the system main relay 5
The positive output terminal 2b and the negative output terminal 2c of the high voltage battery 2 are connected to the positive input terminal 3g and the negative input terminal 3h of the inverter circuit 3, respectively. Thereby, DC power is supplied from the high voltage battery 2 to the inverter circuit 3, and the inverter circuit 3 converts this DC power into AC power and supplies it to the AC motor 4, whereby the AC motor 4 generates torque. When the ignition switch is turned off, the system main relay 5 disconnects the high voltage battery 2 from the inverter circuit 3.

地絡検出回路６は、交流信号発生回路６０（交流信号発生手段）と、地絡検出抵抗６１と、第１地絡判定回路６２（第１地絡判定手段）と、第２地絡判定回路６３（第２地絡判定手段）とから構成されている。交流信号発生回路６０の一端はマイクロコンピュータ９に、他端は地絡検出抵抗６１を介してカップリングコンデンサ７に、さらに、別の一端は車体にそれぞれ接地されている。そして、交流信号発生回路６０は、マイクロコンピュータ９からの信号に基づき、地絡検出抵抗６１を介してカップリングコンデンサ７に一定周波数の矩形波パルスを出力する。第１地絡判定回路６２は、比較回路６２ａと、第１地絡判定基準電源６２ｂとから構成されている。比較回路６２ａの一端は地絡検出抵抗６１とカップリングコンデンサ７との接続点に、他端は第１地絡判定基準電源６２ｂの一端にそれぞれ接続され、第１地絡判定基準電源６２ｂの他端は車体に接地されている。さらに、比較回路６２ａの別の一端はマイクロコンピュータ９に接続されている。そして、第１地絡判定回路６２は、地絡検出抵抗６１とカップリングコンデンサ７との接続点の電圧を第１地絡判定基準電源６２ｂの電圧（第１地絡判定値）と比較し、その比較結果をマイクロコンピュータ９に出力する。第２地絡判定回路６３は、比較回路６３ａと、第２地絡判定基準電源６３ｂとから構成されている。比較回路６３ａの一端は地絡検出抵抗６１とカップリングコンデンサ７との接続点に、他端は第２地絡判定基準電源６３ｂの一端にそれぞれ接続され、第２地絡判定基準電源６３ｂの他端は車体に接地されている。さらに、比較回路６３ａの別の一端はマイクロコンピュータ９に接続されている。そして、第２地絡判定回路６３は、地絡検出抵抗６１とカップリングコンデンサ７との接続点の電圧を第２地絡判定基準電源６３ｂの電圧（第２地絡判定値）と比較し、その比較結果をマイクロコンピュータ９に出力する。   The ground fault detection circuit 6 includes an AC signal generation circuit 60 (AC signal generation means), a ground fault detection resistor 61, a first ground fault determination circuit 62 (first ground fault determination means), and a second ground fault determination circuit. 63 (second ground fault determination means). One end of the AC signal generating circuit 60 is grounded to the microcomputer 9, the other end is grounded to the coupling capacitor 7 via the ground fault detection resistor 61, and the other end is grounded to the vehicle body. Then, the AC signal generation circuit 60 outputs a rectangular wave pulse having a constant frequency to the coupling capacitor 7 via the ground fault detection resistor 61 based on the signal from the microcomputer 9. The first ground fault determination circuit 62 includes a comparison circuit 62a and a first ground fault determination reference power source 62b. One end of the comparison circuit 62a is connected to a connection point between the ground fault detection resistor 61 and the coupling capacitor 7, and the other end is connected to one end of the first ground fault determination reference power source 62b. The end is grounded to the car body. Further, another end of the comparison circuit 62 a is connected to the microcomputer 9. The first ground fault determination circuit 62 compares the voltage at the connection point between the ground fault detection resistor 61 and the coupling capacitor 7 with the voltage (first ground fault determination value) of the first ground fault determination reference power supply 62b. The comparison result is output to the microcomputer 9. The second ground fault determination circuit 63 includes a comparison circuit 63a and a second ground fault determination reference power source 63b. One end of the comparison circuit 63a is connected to a connection point between the ground fault detection resistor 61 and the coupling capacitor 7, and the other end is connected to one end of the second ground fault determination reference power source 63b. The end is grounded to the car body. Further, another end of the comparison circuit 63a is connected to the microcomputer 9. The second ground fault determination circuit 63 compares the voltage at the connection point between the ground fault detection resistor 61 and the coupling capacitor 7 with the voltage (second ground fault determination value) of the second ground fault determination reference power source 63b. The comparison result is output to the microcomputer 9.

カップリングコンデンサ７は、高電圧が印加されても耐えることのできる、例えば高耐圧の電解コンデンサである。このカップリングコンデンサ７の一端は地絡検出抵抗６１、第１地絡判定回路６２ａ、第２地絡判定回路６３ａ及び断線検出回路８に、他端は高電圧バッテリ２の負極側出力端２ｃにそれぞれ接続されている。そのため、地絡検出回路６及び断線検出回路８は高電圧バッテリ２から直流的に絶縁される。   The coupling capacitor 7 is, for example, a high voltage electrolytic capacitor that can withstand even when a high voltage is applied. One end of the coupling capacitor 7 is connected to the ground fault detection resistor 61, the first ground fault determination circuit 62a, the second ground fault determination circuit 63a and the disconnection detection circuit 8, and the other end is connected to the negative output side 2c of the high voltage battery 2. Each is connected. Therefore, the ground fault detection circuit 6 and the disconnection detection circuit 8 are galvanically isolated from the high voltage battery 2.

断線検出回路８は、比較回路８ａと、断線判定基準電源８ｂとから構成されている。比較回路８ａの一端は地絡検出抵抗６１とカップリングコンデンサ７との接続点に、他端は断線判定基準電源８ｂの一端にそれぞれ接続され、断線判定基準電源８ｂの他端は車体に接地されている。さらに、断線判定基準電源８ｂの別の一端はマイクロコンピュータ９に接続されている。そして、断線判定基準電源８ｂは、地絡検出抵抗６１とカップリングコンデンサ７との接続点の電圧を断線判定基準電源８ｂの電圧（断線判定値）と比較し、その比較結果をマイクロコンピュータ９に出力する。   The disconnection detection circuit 8 includes a comparison circuit 8a and a disconnection determination reference power supply 8b. One end of the comparison circuit 8a is connected to the connection point between the ground fault detection resistor 61 and the coupling capacitor 7, the other end is connected to one end of the disconnection determination reference power supply 8b, and the other end of the disconnection determination reference power supply 8b is grounded to the vehicle body. ing. Further, the other end of the disconnection determination reference power supply 8 b is connected to the microcomputer 9. Then, the disconnection determination reference power supply 8b compares the voltage at the connection point between the ground fault detection resistor 61 and the coupling capacitor 7 with the voltage (disconnection determination value) of the disconnection determination reference power supply 8b, and sends the comparison result to the microcomputer 9. Output.

次に、具体的動作について説明する。電気自動車において、イグニッションスイッチがオンされると、インバータ回路３を介して交流モータ４を制御するモータ制御装置（図略）は装置各部のイニシャルチェックを開始する。そして、装置各部に異常がないことが確認されると、モータ制御装置はシステムメインリレー５をオンして高圧バッテリ２をインバータ回路３に接続する。このとき、高電圧バッテリ２の出力電圧、例えば、３００Ｖは、ともに一端が車体に接地されている抵抗値の等しいコモン電圧制御用抵抗３ｉ、３ｊにより分圧される。そのため、高電圧バッテリ２の負極側出力端２ｃに接続されているカップリングコンデンサ７の一端の電圧は−１５０Ｖの負電圧となる。   Next, a specific operation will be described. In an electric vehicle, when an ignition switch is turned on, a motor control device (not shown) that controls the AC motor 4 via the inverter circuit 3 starts an initial check of each part of the device. When it is confirmed that there is no abnormality in each part of the device, the motor control device turns on the system main relay 5 to connect the high voltage battery 2 to the inverter circuit 3. At this time, the output voltage of the high voltage battery 2, for example, 300 V, is divided by the common voltage control resistors 3 i and 3 j having the same resistance value with one end grounded to the vehicle body. Therefore, the voltage at one end of the coupling capacitor 7 connected to the negative output side 2c of the high voltage battery 2 is a negative voltage of −150V.

カップリングコンデンサ７を含む地絡検出回路６から高圧バッテリ２に至る経路で断線が発生していない場合、カップリングコンデンサ７の一端の電圧は、カップリングコンデンサ７のインピーダンスと、カップリングコンデンサ７の他端に接続されている地絡検出回路６及び断線検出回路８の合成内部インピーダンスとにより分圧される。そのため、地絡検出回路６及び断線検出回路８に接続されているカップリングコンデンサ７の他端の電圧は、例えば、−１５Ｖの負電圧となる。その後、このカップリングコンデンサ７の他端の電圧は、地絡検出回路６及び断線検出回路８の合成内部抵抗とカップリングコンデンサ７の容量とによって決まる時定数に基づいて指数関数的に上昇し０Ｖへ収束していく。さらに、カップリングコンデンサ７の他端には、地絡検出抵抗６１を介して交流信号発生回路６０の発生する一定周波数の矩形波パルスが重畳される。そのため、カップリングコンデンサ７の他端の電圧は、図２に示すように、システムメインリレー５がオンすると同時に−１５Ｖまで低下し、その後、指数関数的に上昇する電圧を基準としたパルス状の電圧となる。   When no disconnection occurs in the path from the ground fault detection circuit 6 including the coupling capacitor 7 to the high voltage battery 2, the voltage at one end of the coupling capacitor 7 is the impedance of the coupling capacitor 7 and the coupling capacitor 7. The voltage is divided by the combined internal impedance of the ground fault detection circuit 6 and the disconnection detection circuit 8 connected to the other end. Therefore, the voltage at the other end of the coupling capacitor 7 connected to the ground fault detection circuit 6 and the disconnection detection circuit 8 is, for example, a negative voltage of −15V. Thereafter, the voltage at the other end of the coupling capacitor 7 increases exponentially based on a time constant determined by the combined internal resistance of the ground fault detection circuit 6 and the disconnection detection circuit 8 and the capacitance of the coupling capacitor 7. To converge. Further, a rectangular wave pulse having a constant frequency generated by the AC signal generation circuit 60 is superimposed on the other end of the coupling capacitor 7 via the ground fault detection resistor 61. Therefore, as shown in FIG. 2, the voltage at the other end of the coupling capacitor 7 decreases to −15 V at the same time as the system main relay 5 is turned on, and then has a pulse-like shape based on a voltage that exponentially increases. Voltage.

これに対し、カップリングコンデンサ７を含む地絡検出回路６から高圧バッテリ２に至る経路で断線が発生している場合、カップリングコンデンサ７の他端の電圧は、図３に示すように、システムメインリレー５がオンしても負電圧側に低下することはなく、０Ｖを基準としたパルス状の電圧となる。   On the other hand, when a disconnection occurs in the path from the ground fault detection circuit 6 including the coupling capacitor 7 to the high voltage battery 2, the voltage at the other end of the coupling capacitor 7 is as shown in FIG. Even when the main relay 5 is turned on, the voltage does not decrease to the negative voltage side, and becomes a pulsed voltage with 0V as a reference.

このカップリングコンデンサ７の他端の電圧は、断線検出回路８の比較回路８ａで断線判定基準電源８ｂの電圧、例えば、−１０Ｖと比較される。これにより、カップリングコンデンサ７の他端の電圧が断線判定基準電源８ｂの電圧以上であった場合、断線検出回路８は、カップリングコンデンサ７を含む地絡検出回路６から高圧バッテリ２に至る経路で断線が発生していると判定する。また、それ以外の場合、断線検出回路８は、カップリングコンデンサ７を含む地絡検出回路６から高圧バッテリ２に至る経路で断線は発生しておらず正常であると判定する。   The voltage at the other end of the coupling capacitor 7 is compared with the voltage of the disconnection determination reference power supply 8b, for example, −10V, by the comparison circuit 8a of the disconnection detection circuit 8. Thereby, when the voltage at the other end of the coupling capacitor 7 is equal to or higher than the voltage of the disconnection determination reference power supply 8b, the disconnection detection circuit 8 is connected to the high voltage battery 2 from the ground fault detection circuit 6 including the coupling capacitor 7. It is determined that a disconnection has occurred. In other cases, the disconnection detection circuit 8 determines that the disconnection does not occur in the path from the ground fault detection circuit 6 including the coupling capacitor 7 to the high voltage battery 2 and is normal.

ところで、システムメインリレー５がオンする前に、例えば、インバータ回路３の正極側入力端３ｇで地絡が発生していた場合、システムメインリレー５がオンした後に、高電圧バッテリ２の出力電圧は地絡抵抗１０ａとコモン電圧制御用抵抗３ｊとにより分圧される。ここで、地絡抵抗１０ａはコモン電圧制御用抵抗３ｊに比べ抵抗値が非常に小さいため、高電圧バッテリ２の負極側出力端２ｃに接続されているカップリングコンデンサ７の一端の電圧はほぼ−３００Ｖの負電圧となる。このカップリングコンデンサ７の一端の電圧は、カップリングコンデンサ７のインピーダンスと、カップリングコンデンサ７の他端に接続されている地絡検出回路６及び断線検出回路８の合成内部インピーダンスとにより分圧される。そのため、地絡検出回路６及び断線検出回路８に接続されているカップリングコンデンサ７の他端の電圧は、例えば、−３０Ｖの負電圧となる。その後、このカップリングコンデンサ７の他端の電圧は、地絡検出回路６及び断線検出回路８の合成内部抵抗とカップリングコンデンサ７の容量とによって決まる時定数に基づいて指数関数的に上昇し０Ｖへ収束していく。さらに、カップリングコンデンサ７の他端には、地絡抵抗６１を介して交流信号発生回路６０から出力され、地絡検出抵抗６１と地絡抵抗１０ａとにより分圧されることで波高値の低下した矩形波パルスが重畳される。そのため、カップリングコンデンサ７の他端の電圧は、図４に示すように、システムメインリレー５がオンすると同時に−３０Ｖまで低下し、その後、指数関数的に上昇する電圧を基準とした波高値の低下したパルス状の電圧となる。このカップリングコンデンサ７の他端の電圧は、第１地絡判定回路６２の比較回路６２ａで断線判定基準電源８ｂの電圧より小さい第１地絡判定基準電源６２ｂの電圧、例えば−２５Ｖと比較される。これにより、カップリングコンデンサ７の他端の電圧が第１地絡判定基準電源６２ｂの電圧以下であった場合、第１地絡判定出回路６２ａは、インバータ回路３の正極側入力端３ｇで地絡が発生していると判定する。   By the way, before the system main relay 5 is turned on, for example, when a ground fault has occurred at the positive input side 3g of the inverter circuit 3, the output voltage of the high voltage battery 2 is changed after the system main relay 5 is turned on. The voltage is divided by the ground fault resistor 10a and the common voltage control resistor 3j. Here, since the resistance value of the ground fault resistor 10a is much smaller than that of the common voltage control resistor 3j, the voltage at one end of the coupling capacitor 7 connected to the negative output side 2c of the high voltage battery 2 is approximately −. The negative voltage is 300V. The voltage at one end of the coupling capacitor 7 is divided by the impedance of the coupling capacitor 7 and the combined internal impedance of the ground fault detection circuit 6 and the disconnection detection circuit 8 connected to the other end of the coupling capacitor 7. The Therefore, the voltage at the other end of the coupling capacitor 7 connected to the ground fault detection circuit 6 and the disconnection detection circuit 8 is, for example, a negative voltage of −30V. Thereafter, the voltage at the other end of the coupling capacitor 7 increases exponentially based on a time constant determined by the combined internal resistance of the ground fault detection circuit 6 and the disconnection detection circuit 8 and the capacitance of the coupling capacitor 7. To converge. Further, the other end of the coupling capacitor 7 is output from the AC signal generation circuit 60 via the ground fault resistor 61, and is divided by the ground fault detection resistor 61 and the ground fault resistor 10a, thereby lowering the peak value. The rectangular wave pulse is superimposed. Therefore, as shown in FIG. 4, the voltage at the other end of the coupling capacitor 7 decreases to −30 V at the same time as the system main relay 5 is turned on, and then has a peak value with reference to a voltage that exponentially increases. A reduced pulse voltage is obtained. The voltage at the other end of the coupling capacitor 7 is compared with the voltage of the first ground fault determination reference power supply 62b, for example, −25V, which is smaller than the voltage of the disconnection determination reference power supply 8b by the comparison circuit 62a of the first ground fault determination circuit 62. The Thereby, when the voltage at the other end of the coupling capacitor 7 is equal to or lower than the voltage of the first ground fault determination reference power supply 62b, the first ground fault determination output circuit 62a is connected to the ground side at the positive input terminal 3g of the inverter circuit 3. It is determined that an entanglement has occurred.

また、システムメインリレー５がオンする前に、例えば、インバータ回路３の負極側入力端３ｈで地絡が発生していた場合、システムメインリレー５がオンした後に、高電圧バッテリ２の出力電圧は地絡抵抗１０ｂとコモン電圧制御用抵抗３ｉとにより分圧される。ここで、地絡抵抗１０ｂはコモン電圧制御用抵抗３ｉに比べ抵抗値が非常に小さいため、高電圧バッテリ２の負極側出力端２ｃに接続されているカップリングコンデンサ７の一端の電圧はほぼ０Ｖとなる。そのため、地絡検出回路６及び断線検出回路８に接続されているカップリングコンデンサ７の他端の電圧もほぼ０Ｖとなる。さらに、カップリングコンデンサ７の他端には、地絡抵抗６１を介して交流信号発生回路６０から出力され、地絡検出抵抗６１と地絡抵抗１０ａとにより分圧されることで波高値の低下した矩形波パルスが重畳される。そのため、カップリングコンデンサ７の他端の電圧は、図５に示すように、システムメインリレー５がオンしても大きく変化することはなく、ほぼ０Ｖを基準とした波高値の低下したパルス状の電圧となる。このカップリングコンデンサ７の他端の電圧は、断線検出回路８の比較回路８ａで断線判定基準電源８ｂの電圧−１０Ｖと比較される。そのため、実際にはインバータ回路３の負極側入力端３ｈの地絡であるが、カップリングコンデンサ７の他端の電圧は断線判定基準電源８ｂの電圧以上であり、断線検出回路８は、カップリングコンデンサ７を含む地絡検出回路６から高圧バッテリ２に至る経路で断線が発生しているものと判定し異常を検出する。このインバータ回路３の負極側入力端３ｈの地絡は、後述する第２地絡判定回路によって最終的に地絡と判定される。   Further, before the system main relay 5 is turned on, for example, when a ground fault occurs at the negative side input terminal 3h of the inverter circuit 3, the output voltage of the high voltage battery 2 is changed after the system main relay 5 is turned on. The voltage is divided by the ground fault resistor 10b and the common voltage control resistor 3i. Here, since the resistance value of the ground fault resistor 10b is much smaller than that of the common voltage control resistor 3i, the voltage at one end of the coupling capacitor 7 connected to the negative output side 2c of the high voltage battery 2 is almost 0V. It becomes. Therefore, the voltage at the other end of the coupling capacitor 7 connected to the ground fault detection circuit 6 and the disconnection detection circuit 8 is also substantially 0V. Further, the other end of the coupling capacitor 7 is output from the AC signal generation circuit 60 via the ground fault resistor 61, and is divided by the ground fault detection resistor 61 and the ground fault resistor 10a, thereby lowering the peak value. The rectangular wave pulse is superimposed. Therefore, as shown in FIG. 5, the voltage at the other end of the coupling capacitor 7 does not change greatly even when the system main relay 5 is turned on, and has a pulse-like shape with a reduced peak value with reference to approximately 0V. Voltage. The voltage at the other end of the coupling capacitor 7 is compared with the voltage −10 V of the disconnection determination reference power supply 8 b by the comparison circuit 8 a of the disconnection detection circuit 8. Therefore, although it is actually a ground fault at the negative input side 3h of the inverter circuit 3, the voltage at the other end of the coupling capacitor 7 is equal to or higher than the voltage of the disconnection determination reference power supply 8b, and the disconnection detection circuit 8 It is determined that a disconnection has occurred in the path from the ground fault detection circuit 6 including the capacitor 7 to the high voltage battery 2, and an abnormality is detected. The ground fault at the negative input side 3h of the inverter circuit 3 is finally determined as a ground fault by a second ground fault determination circuit described later.

システムメインリレー５がオンしてカップリングコンデンサ７の他端の電圧が収束し、第２地絡判定回路６３が地絡を確実に検出できる時間ｔ１になると、第２地絡判定回路６３はカップリングコンデンサ７の他端の電圧を第２地絡判定基準電源６３ｂの電圧と比較する。これにより、カップリングコンデンサ７の他端の電圧が第２地絡判定基準電源６３ｂの電圧以下であった場合、第２地絡判定回路６３は、高電圧バッテリ２、インバータ回路３及び交流モータ４の少なくともいずれかで地絡が発生していると判定する。前述した、システムメインリレー５がオンする前にインバータ回路３の正極側入力端３ｇで地絡が発生している場合であっても、これにより最終的に地絡と判定される。また、それ以外の場合、第２地絡判定回路６３は、高電圧バッテリ２、インバータ回路３及び交流モータ４地絡は発生しておらず正常であると判定する。   When the system main relay 5 is turned on and the voltage at the other end of the coupling capacitor 7 converges, and the time t1 at which the second ground fault determination circuit 63 can reliably detect the ground fault is reached, the second ground fault determination circuit 63 sets the cup. The voltage at the other end of the ring capacitor 7 is compared with the voltage of the second ground fault determination reference power source 63b. Thus, when the voltage at the other end of the coupling capacitor 7 is equal to or lower than the voltage of the second ground fault determination reference power source 63b, the second ground fault determination circuit 63 is connected to the high voltage battery 2, the inverter circuit 3, and the AC motor 4. It is determined that a ground fault has occurred in at least one of the above. Even if the ground fault has occurred at the positive input terminal 3g of the inverter circuit 3 before the system main relay 5 is turned on, it is finally determined as a ground fault. In other cases, the second ground fault determination circuit 63 determines that the high-voltage battery 2, the inverter circuit 3, and the AC motor 4 have no ground fault and are normal.

断線検出回路８、第１地絡判定回路６２及び第２地絡判定回路６３の判定結果はマイクロコンピュータ９に入力され、マイクロコンピュータ９は必要に応じてＬＥＤ等を点灯し警報する。   The determination results of the disconnection detection circuit 8, the first ground fault determination circuit 62, and the second ground fault determination circuit 63 are input to the microcomputer 9, and the microcomputer 9 lights up an LED or the like as necessary to give an alarm.

最後に効果について説明する。本実施形態によれば、地絡検出装置１は、システムメインリレー５が高電圧バッテリ２をインバータ回路３に接続した後に、断線検出回路８で地絡検出回路６とカップリングコンデンサ７との接続点の電圧の大きさを所定の断線判定基準電源８ｂの電圧と比較することができる。従って、カップリングコンデンサ７を含む地絡検出回路６から高電圧バッテリ２に至る経路における断線を検出することができる。   Finally, the effect will be described. According to the present embodiment, the ground fault detection device 1 is connected to the ground fault detection circuit 6 and the coupling capacitor 7 by the disconnection detection circuit 8 after the system main relay 5 connects the high voltage battery 2 to the inverter circuit 3. The magnitude of the voltage at the point can be compared with the voltage of the predetermined disconnection determination reference power supply 8b. Accordingly, it is possible to detect disconnection in the path from the ground fault detection circuit 6 including the coupling capacitor 7 to the high voltage battery 2.

また、地絡検出装置１は、システムメインリレー５が高電圧バッテリ２をインバータ回路３に接続した後に、第１地絡判定回路６２で地絡検出回路６とカップリングコンデンサ７との接続点の電圧の大きさを所定の第１地絡判定基準電源６２ｂの電圧と比較することができる。従って、高電圧バッテリ２、インバータ回路３又は交流モータ４の少なくともいずれかの地絡を断線又は地絡として検出することができる。   Further, the ground fault detection device 1 is configured such that after the system main relay 5 connects the high voltage battery 2 to the inverter circuit 3, the first ground fault determination circuit 62 determines the connection point between the ground fault detection circuit 6 and the coupling capacitor 7. The magnitude of the voltage can be compared with the voltage of the predetermined first ground fault determination reference power source 62b. Therefore, a ground fault of at least one of the high voltage battery 2, the inverter circuit 3, or the AC motor 4 can be detected as a disconnection or a ground fault.

さらに、地絡検出装置１は、システムメインリレー５が高電圧バッテリ２をインバータ回路３に接続してから所定の時間経過後に、第２地絡判定回路６３で地絡検出回路６とカップリングコンデンサ７との接続点の電圧の大きさを所定の第２地絡判定基準電源６３ｂの電圧と比較することができる。従って、システムメインリレー５が高電圧バッテリ２をインバータ回路３に接続してから所定の時間経過後に、高電圧バッテリ２、インバータ回路３又は交流モータ４の少なくともいずれかの地絡を検出することができる。   Further, the ground fault detection device 1 includes a ground fault detection circuit 6 and a coupling capacitor after the predetermined time has elapsed since the system main relay 5 connected the high voltage battery 2 to the inverter circuit 3. 7 can be compared with the voltage of the predetermined second ground fault determination reference power source 63b. Therefore, it is possible to detect a ground fault of at least one of the high voltage battery 2, the inverter circuit 3, and the AC motor 4 after a predetermined time has elapsed since the system main relay 5 connected the high voltage battery 2 to the inverter circuit 3. it can.

なお、上述した実施形態においては、インバータ回路３の正極側入力端３ｇ及び負極側入力端３ｈがコモン電圧制御用抵抗３ｉ、３ｊを介してそれぞれ車体に接地されている例を挙げているが、これに限られるものではない。例えば、高圧バッテリ２、インバータ回路３及び交流モータ４は車体に対して絶縁されていてもよい。この場合、インバータ回路３の正極側入力端３ｇ及び負極側入力端３ｈが高抵抗を介してそれぞれ車体に接地されていることと等価であり、前記と同様の効果が得られる。   In the above-described embodiment, an example is given in which the positive side input terminal 3g and the negative side input terminal 3h of the inverter circuit 3 are grounded to the vehicle body via the common voltage control resistors 3i and 3j, respectively. It is not limited to this. For example, the high voltage battery 2, the inverter circuit 3, and the AC motor 4 may be insulated from the vehicle body. In this case, it is equivalent to that the positive electrode side input terminal 3g and the negative electrode side input terminal 3h of the inverter circuit 3 are each grounded to the vehicle body via a high resistance, and the same effect as described above can be obtained.

また、上述した実施形態においては、カップリングコンデンサ７の一端が高電圧バッテリ２の負極側出力端２ｃに接続されている例を挙げているが、これに限られるものではない。例えば、カップリングコンデンサ７の一端が高電圧バッテリ２の正極側出力端２ｂに接続されていてもよい。この場合、システムメインリレー５がオンされると、地絡検出回路６及び断線検出回路８に接続されているカップリングコンデンサ７の他端の電圧は、本実施形態とは逆方向の正電圧側に変化する。しかし、断線判定基準電源８ｂ及び第１地絡判定基準電源６２ｂの極性を反転させることで前記と同様の効果が得られる。   In the above-described embodiment, an example in which one end of the coupling capacitor 7 is connected to the negative-side output terminal 2c of the high-voltage battery 2 is described, but the present invention is not limited to this. For example, one end of the coupling capacitor 7 may be connected to the positive output side 2 b of the high voltage battery 2. In this case, when the system main relay 5 is turned on, the voltage at the other end of the coupling capacitor 7 connected to the ground fault detection circuit 6 and the disconnection detection circuit 8 is the positive voltage side in the direction opposite to the present embodiment. To change. However, the same effect as described above can be obtained by reversing the polarities of the disconnection determination reference power supply 8b and the first ground fault determination reference power supply 62b.

本実施形態における地絡検出装置の回路図を示す。The circuit diagram of the ground fault detection apparatus in this embodiment is shown. 断線が発生していない場合の接続点の電圧波形を示す。The voltage waveform of the connection point when no disconnection has occurred is shown. 断線が発生している場合の接続点の電圧波形を示す。The voltage waveform of a connection point when the disconnection has occurred is shown. 高電圧バッテリの正極側が地絡している場合の接続点の電圧波形を示す。The voltage waveform of the connection point when the positive electrode side of the high voltage battery is grounded is shown. 高電圧バッテリの負極側が地絡している場合の接続点の電圧波形を示す。The voltage waveform of a connection point when the negative electrode side of a high voltage battery has a ground fault is shown.

符号の説明Explanation of symbols

１ ・・・ 地絡検出装置
２ ・・・ 高電圧バッテリ（直流電源）
２ａ ・・・ 電池モジュール
２ｂ ・・・ 正極側出力端
２ｃ ・・・ 負極側出力端
３ ・・・ インバータ回路（負荷）
３ｇ ・・・ 正極側入力端
３ｈ ・・・ 負極側入力端
３ｉ、３ｊ ・・・ コモン電圧制御用抵抗
４ ・・・ 交流モータ（負荷）
５ ・・・ システムメインリレー
６ ・・・ 地絡検出回路（地絡検出手段）
６０ ・・・ 交流信号発生回路（交流信号発生手段）
６１ ・・・ 地絡検出抵抗
６２ ・・・ 第１地絡判定回路（第１地絡判定手段）
６２ａ ・・・ 比較回路
６２ｂ ・・・ 第１地絡判定基準電源
６３ ・・・ 第２地絡判定回路（第２地絡判定手段）
６３ａ ・・・ 比較回路
６３ｂ ・・・ 第２地絡判定基準電源
７ ・・・ カップリングコンデンサ
８ ・・・ 断線検出回路（断線検出手段）
８ａ ・・・ 比較回路
８ｂ ・・・ 断線判定基準電源
９ ・・・ マイクロコンピュータ DESCRIPTION OF SYMBOLS 1 ... Ground fault detection apparatus 2 ... High voltage battery (DC power supply)
2a: Battery module 2b: Positive output terminal 2c: Negative output terminal 3: Inverter circuit (load)
3g: Positive side input terminal 3h: Negative side input terminal 3i, 3j: Common voltage control resistor 4: AC motor (load)
5... System main relay 6... Ground fault detection circuit (ground fault detection means)
60 ... AC signal generating circuit (AC signal generating means)
61: Ground fault detection resistor 62: First ground fault determination circuit (first ground fault determination means)
62a ... comparison circuit 62b ... first ground fault judgment reference power supply 63 ... second ground fault judgment circuit (second ground fault judgment means)
63a ... comparison circuit 63b ... second ground fault judgment reference power supply 7 ... coupling capacitor 8 ... disconnection detection circuit (disconnection detection means)
8a: comparison circuit 8b: disconnection judgment reference power supply 9: microcomputer

Claims (3)

車体に対して絶縁される直流電源と、前記車体に対して絶縁されるとともに前記直流電源から電力を供給されることにより作動する負荷と、前記直流電源と前記負荷とを接続又は遮断する断続手段と、前記車体に接地されるとともに前記断続手段が前記直流電源を前記負荷に接続した後に前記直流電源又は前記負荷の少なくともいずれかの地絡を検出する地絡検出手段と、前記地絡検出手段と前記直流電源とを接続するカップリングコンデンサとを備えた地絡検出装置において、
さらに、前記断続手段が前記直流電源を前記負荷に接続した後に前記地絡検出手段と前記カップリングコンデンサとの接続点の電圧の大きさを所定の断線判定値と比較することにより前記カップリングコンデンサを含む前記地絡検出手段から前記直流電源に至る経路における断線を検出する断線検出手段を有することを特徴とする地絡検出装置。 A DC power source that is insulated from the vehicle body; a load that is insulated from the vehicle body and that is operated by being supplied with electric power from the DC power source; and an intermittent unit that connects or disconnects the DC power source and the load. And a ground fault detection means for detecting a ground fault of at least one of the DC power supply or the load after the intermittent means connects the DC power supply to the load, and the ground fault detection means. In a ground fault detection device comprising a coupling capacitor that connects the DC power source and
Further, the coupling capacitor compares the magnitude of the voltage at the connection point between the ground fault detection unit and the coupling capacitor with a predetermined disconnection determination value after the intermittent unit connects the DC power supply to the load. A ground fault detection device comprising: a disconnection detection means for detecting a disconnection in a path from the ground fault detection means including the DC power supply. 前記地絡検出手段は、前記接続点に接続されるとともに前記断続手段が前記直流電源を前記負荷に接続した後に前記接続点の電圧の大きさを所定の第１地絡判定値と比較することにより、前記断続手段が前記直流電源を前記負荷に接続する前に発生した前記地絡を判定する第１地絡判定手段を有することを特徴とする請求項１記載の地絡検出装置。   The ground fault detection means is connected to the connection point, and the intermittent means compares the magnitude of the voltage at the connection point with a predetermined first ground fault judgment value after the DC power source is connected to the load. The ground fault detection device according to claim 1, further comprising: a first ground fault determination unit that determines the ground fault generated before the intermittent unit connects the DC power source to the load. 前記地絡検出手段は、交流信号を発生する交流信号発生手段と、一端が前記交流信号発生手段に接続されるとともに他端が前記カップリングコンデンサに接続される地絡検出抵抗と、前記接続点に接続されるとともに前記断続手段が前記直流電源を前記負荷に接続してから所定の時間経過後に前記接続点の電圧の大きさを所定の第２地絡判定値と比較することにより前記地絡を判定する第２地絡判定手段とを有することを特徴とする請求項１又は２記載の地絡検出装置。   The ground fault detection means includes an AC signal generation means for generating an AC signal, a ground fault detection resistor having one end connected to the AC signal generation means and the other end connected to the coupling capacitor, and the connection point. And connecting the DC power source to the load by the intermittent means and comparing the voltage level at the connection point with a predetermined second ground fault determination value after a lapse of a predetermined time. The ground fault detection device according to claim 1, further comprising: a second ground fault determination unit that determines whether or not.
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