JP2009097914A - Electrical leakage detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrical leakage detection method which can easily detect electrical leakage. <P>SOLUTION: The electrical leakage detection method is for an electric circuit, having a second high-potential voltage system 22, through which higher voltage electricity passes than a first high-potential voltage system 11 and a low-potential circuit, which are electrically insulated from two-channel high-voltage power source which obtains a high voltage and a high voltage obtained by boosting it, and comprises a first high-potential voltage system resistance circuit 4, which connects the high-potential voltage system 11 to a set potential through at least two resistors Ra, Rb; a second high-potential voltage system resistance circuit 5 which connects the second high-potential voltage system 22 to a set potential through at least two resistors Rc, Rd; and a connecting circuit which connects the neutral point of the two resistors Ra, Rb and the neutral point of the two resistors Rc, Rd, detecting an electrical leakage in a high-voltage circuit, on the basis of the potential of the connecting circuit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a leakage detection method for detecting leakage in a circuit including a high voltage circuit and a low voltage circuit independently.

  2. Description of the Related Art In recent years, high-voltage electricity is used as electricity for generating driving force in vehicles that can run using electric power, such as electric vehicles and hybrid vehicles. Thus, the circuit through which high voltage electricity flows (high voltage circuit) is in a floating state separated from the body ground of the vehicle so as not to get an electric shock even if a person touches a high voltage power source. When dielectric breakdown occurs, an electric shock is generated because a current flows when a person touches the high voltage system. For this reason, it is important to detect leakage due to dielectric breakdown.

  As a method for detecting a leakage in a high voltage circuit, for example, a method for detecting a leakage by connecting a leakage detection circuit to a high voltage circuit via a coupling capacitor and reducing the waveform value of a pulse input to the coupling capacitor. is there. This detection device has a problem that the detection of electric leakage such as erroneous detection is not sufficient because the waveform value of the pulse changes even when the voltage of electricity flowing through the high-voltage circuit fluctuates. In addition, it is necessary to newly connect a leakage detection circuit for leakage detection, which increases the physique and cost of the apparatus.

  Japanese Patent Application Laid-Open No. H10-228688 discloses a detection device that detects a leakage of another high voltage circuit.

  Patent Document 1 discloses a high-voltage DC power supply, a plurality of protective resistors and detection resistors connected in series between the positive and negative sides of the high-voltage DC power supply, and one end of these detection resistors connected to an electric vehicle, There is disclosed a leakage detection device including a switch that is grounded to a body ground such as a train and a leakage determination unit that determines leakage of an electric vehicle or a train.

Also in this leakage detection device, it is necessary to connect a new device such as a leakage determination unit, a plurality of resistors and switches to the circuit, and there is a problem that the cost increases.
Japanese Patent Laid-Open No. 6-153301

  This invention is made | formed in view of the said actual condition, and makes it a subject to provide the leak detection method which can detect a leak easily.

  In order to solve the above-mentioned problems, the present inventor has made studies of the present invention as a result of repeated studies on detection of leakage in a high voltage circuit.

  In other words, the leakage detection method of the present invention according to claim 1 is a circuit having an insulated low-potential circuit and a high-potential circuit, and the high-potential circuit includes a power supply voltage and a booster power source that boosts the first high-voltage circuit. A method for detecting a leakage between the low potential circuit and the high potential circuit, comprising: a potential voltage system circuit and a second high potential voltage system circuit, wherein at least the voltage of the first high potential voltage system circuit is set to two resistors Ra , Rb, the first high-potential voltage circuit resistor circuit connected to the predetermined potential of the low-potential circuit, and at least the voltage of the second high-potential circuit circuit through the two resistors Rc, Rd. A second high potential voltage system resistor circuit connected to a predetermined potential, and a connection circuit connecting a neutral point of the two resistors Ra and Rb and a neutral point of the two resistors Rc and Rd, the connection The leakage of the high potential circuit is detected based on the potential of the circuit.

  The detection method according to claim 2 is the detection device according to claim 1, wherein the first high potential voltage system circuit and the second high potential voltage system circuit are connected in parallel to the low potential circuit. It is characterized by being.

  The detection method according to claim 3 is the detection method according to claim 1, wherein the first high potential voltage system circuit and the second high potential voltage system circuit are the first high potential voltage. A part of the circuit for differentially detecting the voltage of the system circuit or the second high potential voltage circuit is constituted.

  According to a first aspect of the present invention, there is provided a first high potential voltage system in which a high potential circuit including a first high potential voltage system and a second high potential voltage system and a low potential circuit are connected to a predetermined potential. The leakage detection is performed from the change in the potential of the connection circuit that connects the resistance circuit and the second high potential voltage system resistance circuit at their neutral points. In the leakage detection method of the present invention, when a short circuit occurs due to leakage, any of Ra to Rd is bypassed, and the potential of the connection circuit changes. The leakage can be detected from this potential change. That is, it is no longer necessary to add a new device for detecting electric leakage as in the prior art. That is, the leakage detection method of the present invention can detect a leakage in a circuit without adding a leakage detection circuit.

  Further, in the leakage detection method of the present invention, since the leakage is detected from the change in the potential of the connection circuit, the leakage is detected even if the voltages of the first high potential voltage system circuit and the second high potential voltage system circuit fluctuate. Demonstrate the effects that can be.

  According to the leakage detection method of the present invention described in claim 2, the first high potential voltage system and the second high potential voltage system are connected in parallel to the low potential circuit, so that the predetermined potential is supplied to the first high potential voltage system. Therefore, it can be within the potential of the second high potential voltage system, and the predetermined potential can be easily obtained. By connecting the predetermined potential of the first high potential voltage system resistor circuit and the second high potential voltage system resistor circuit to the negative electrode of the low potential power source, it becomes possible to set the predetermined potential to the GND of the low potential circuit, The potential of the connection circuit can be easily calculated.

  According to the leakage detection method of the present invention described in claim 3, it is possible to use the voltage detection circuit that is conventionally assembled in each of the first high potential voltage system circuit and the second high potential voltage system circuit. The effect of eliminating the need to assemble the circuit device is exhibited.

  Hereinafter, the present invention will be described using specific embodiments.

(Example embodiment)
In the present embodiment, a circuit having the configuration shown in FIG. 1, which is a booster circuit that boosts the voltage of the battery 10 of the high voltage circuit 1 by the booster 3 and applies a high voltage to the high potential voltage system 22. The leakage of the high potential system circuit and the low potential system circuit is detected. The circuit having the configuration shown in FIG. 1 is used in a booster circuit of a hybrid vehicle or an electric vehicle.

  The first high potential voltage system 11 is a circuit in which the battery 10 and the booster 3 are electrically connected.

  The second high potential voltage system 22 is a circuit to which a high voltage boosted by the boosting unit 3 is applied. In FIG. 1, a motor M is connected via an inverter INV.

The first high potential voltage system resistor circuit 4 is connected to the first high potential voltage system 11. The first high potential voltage system resistor circuit 4 includes a path 4A for connecting a point A on the high potential side of the first high potential voltage system 11 to a set potential via two resistors R ₁ and R ₃ , and a first high potential A path 4B connecting the point B on the low potential side of the voltage system 11 to the set potential via the two resistors R ₂ and R ₄ , a neutral point of the two resistors R ₁ and R ₃ of the path 4A and the path 4B And a voltmeter 40 that detects a voltage from the difference between the neutral points of the two resistors R ₂ and R ₄ . That is, in the low voltage circuit 1, the voltage is differentially detected by the voltmeter 40.

The second high potential voltage system resistor circuit 5 is connected to the second high potential voltage system 22. The second high potential voltage system resistor circuit 5 includes a path 5A for connecting a high potential side point C of the second high potential voltage system 2 to a set potential via two resistors R ₅ and R ₇ , and a high potential voltage system. The path 5B connecting the point D on the low potential side 22 to the set potential via the two resistors R ₆ and R ₈ , the neutral point of the two resistors R ₅ and R _{7 in} the path 5A, and the two paths 5B A voltmeter 50 that detects a voltage from the difference between the neutral points of the resistors R ₆ and R ₈ . That is, in the second high potential voltage system circuit 2, a voltage is differentially detected by the voltmeter 50.

  In the high voltage system circuit, the set potential to which the four paths 4A, 4B, 5A, and 5B are connected is the same potential in all of the low levels, and is a predetermined potential of the low potential system circuit.

(Leakage detection)
The configuration of the first high potential voltage system resistor circuit 4 and the second high potential voltage system resistor circuit 5 of the high potential circuit shown in FIG. 1 can be considered as the circuit configuration shown in FIG. 2, Vl: potential at point A of high potential circuit 1, Vh: potential at point C of high potential circuit 2, high voltage GND: potential at points D and B of high voltage circuit 2, setting GND: Indicates the set potential of the low potential system.

  The set potential in the circuit shown in FIG. 2 is obtained as described below.

First, the circuit having the configuration shown in FIG. 2 is considered as the circuit shown in FIG. That, _Ra: the combined resistance of the _R 1, R _{3, Rb:} the combined resistance of the _R 2, R _{4, Rc:} the combined resistance of the _R 5, R _{7, Rc:} the combined resistance of the _R 6, R _8, Ia: the Ra The electric current that flows, Ic: the electric current that flows through Rc, and Ie: the electric current that flows through the combined resistance of Rb and Rd.

  When the potential of the set GND is V, the following formulas 1 to 4 are established.

  From the formulas 1 to 4, the following formula 5 is derived.

  As shown in Formula 5, Vh and Vl constituting the potential (setting potential) V of the setting GND are the differentials of the first high potential voltage system resistance circuit 4 and the second high potential voltage system resistance circuit 5, respectively. Are obtained by the voltmeters 40 and 50, and the respective resistance values are obtained when the circuit is formed. That is, it is a known value in a high voltage system having a booster circuit, and the set potential of this booster circuit can be obtained.

  Then, the leakage detection (determination) can be performed from the comparison between the measured value of the potential of the set GND and the calculated set potential. The determination of leakage can be made, for example, by comparing the measured value with a preset threshold value.

(Example)
More specifically, a method for detecting leakage will be described.

  In the circuit shown in FIG. 2, when Ra, Rb, Rc, Rd: 8 MΩ, Vl potential: 250 V, and Vh potential: 650 V (FIG. 4) (FIG. 4), the potential (setting potential) V of the set GND is (250 + 650). ) / 4 = 225V.

  When a leakage occurs (short circuit with the low potential circuit (set potential)) on the high potential side (near point C) of the second high potential voltage system resistor circuit 2, as shown in FIG. The second high potential voltage system 22 and the setting GND are connected through a parallel path. In this state, the measured value of the potential at the setting GND is the potential Vh = 650 V of the high voltage circuit 2. That is, the measured value is larger than when there is no leakage.

  Further, when a leakage (short circuit with the low potential circuit (set potential)) occurs on the low potential side (near point D) of the second high potential voltage system circuit 2, as shown in FIG. 6, it is in parallel with the resistor Rd. The high voltage GND and the setting GND are connected through a simple path. In this state, the measured value of the potential at the setting GND is the potential of the high voltage GND = 0V. That is, the measured value is smaller than when there is no leakage.

  As described above, when leakage occurs, the measured value of the potential at the set GND changes greatly. For this reason, it is possible to determine the leakage by setting the threshold as shown in FIG.

  Here, in the above embodiment, the explanation has been made using the leakage due to a short circuit with a short-circuit path of 0Ω. However, even when the leakage path has a resistance value, the determination of the leakage can be performed similarly.

(Other forms)
In the above embodiment, the leakage is determined by measuring the set potential. However, the leakage may be determined by measuring the potential at point E in FIG.

  From the above formula 5, the voltage Ve at the point E in FIG. 1 shown in the formula 6 can be derived.

As shown in Equation 6, the voltage Ve at the point E can be obtained from Vh and V and the resistors R ₅ and R ₇ . That is, the potential can be measured at a point in the high-voltage circuit 5 where the potential can be measured more easily than the potential of the set GND (set potential).

More specifically, the voltage Ve at the point E in the case shown in FIG. 4 is (650-225) × (resistance divided value of R ₅ , R ₇ ), and can be calculated in the same manner as in the above embodiment. . That is, in the present embodiment example, since the potential (voltage) can be measured more easily, the leakage can be detected more easily.

It is the figure which showed the structure of the circuit of the example of an embodiment. It is the figure which showed the structure of the 1st and 2nd high potential voltage type | system | group resistance circuit. It is the figure which showed the structure of the 1st and 2nd high potential voltage type | system | group resistance circuit. It is the figure which showed the structure of the 1st and 2nd high potential voltage type | system | group resistance circuit. It is the figure which showed the structure of the 1st and 2nd high potential voltage type | system | group resistance circuit at the time of an electric leakage. It is the figure which showed the structure of the 1st and 2nd high potential voltage type | system | group resistance circuit at the time of an electric leakage. It is the graph which showed the measured value and threshold value of the setting potential.

Explanation of symbols

1: high voltage circuit 10: battery 11: first high potential voltage system 22: second high potential voltage system 3: boosting unit 4: first high potential voltage system resistor circuit 5: second high potential voltage system resistor circuit

Claims (3)

A circuit having an insulated low-potential circuit and a high-potential circuit, the high-potential circuit having a first high-potential voltage system circuit and a second high-potential voltage system circuit of a power source voltage and a boosted power source that boosts the power source voltage; A leakage detection method between the low potential circuit and the high potential circuit,
A first high-potential voltage system circuit resistor circuit that connects at least the voltage of the first high-potential voltage system circuit to a predetermined potential of the low-potential circuit via two resistors Ra and Rb;
A second high potential voltage system resistor circuit for connecting at least the voltage of the second high potential system circuit to a predetermined potential of the low potential circuit via two resistors Rc and Rd;
A connection circuit connecting the neutral points of the two resistors Ra and Rb and the neutral points of the two resistors Rc and Rd;
Have
A leakage detection method, comprising: detecting leakage in the high potential circuit based on the potential of the connection circuit.   The leakage detection method according to claim 1, wherein the first high potential voltage system circuit and the second high potential voltage system circuit are circuits connected in parallel to the low potential circuit.   The first high potential voltage system circuit and the second high potential voltage system circuit constitute part of a circuit for differentially detecting the voltage of the first high potential voltage system circuit or the second high potential voltage circuit. Item 3. The leakage detection method according to any one of Items 1 and 2.