JP2010124578A - Disconnection detection circuit of ground wire of vehicle charging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive disconnection detection circuit for easily detecting disconnection of a ground wire of a vehicle charging cable without using a communication wire. <P>SOLUTION: The disconnection detection circuit of the ground wire 13 of the vehicle charging cable includes a first power supply wire 11, a second power supply wire 12 and the ground wire 13. The circuit includes a first detection circuit 16 detecting inter-wire voltage between the ground wire 13 and the first power supply wire 11 and a second detection circuit 17 detecting inter-wire voltage between the ground wire 13 and the second power supply wire 12. The detection circuits are provided with equal voltage dividing resistors 19 to 23. Diodes 18 and 21 are arranged between the voltage dividing resistors and the power supply wires. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an earth wire disconnection detection circuit that can easily detect whether or not an earth wire of an automobile charging system used for charging an electric vehicle (EV) is disconnected.

  Charging the electric vehicle (EV) is performed by connecting the distribution board and the power receiving connector on the vehicle side with a vehicle charging cable (Patent Document 1). Since the charging cable, the charging box to which the charging cable is connected, and the electric vehicle are touched by a person, it is necessary to secure the ground of the part touched by the person in order to protect the human body. For this reason, a ground wire is incorporated in the charging cable and is grounded to the ground via the ground terminal of the distribution board. The charging cable includes a first power line and a second power line in addition to the ground line. In addition, a communication line is incorporated.

  When the charging cable is connected to the power receiving connector on the vehicle side, the ground wire is connected to the vehicle body, and the other end of the ground wire is grounded via the ground terminal of the distribution board. For this reason, even if a leakage occurs in the state where a person touches the car, the human body is protected by the ground wire.

  A protective device (CCID) with a built-in leakage detector is installed in the middle of the charging cable (portion close to the power receiving connector of the automobile), and a power supply relay is housed in the protective device (CCID). At the time of charging, a signal is sent from the automobile side to the communication line and the ground line, and the feeding relay is operated to control the start and end of charging. In order to perform this control reliably, if the vehicle and the protective device are constantly communicating during charging and communication is not performed normally, the disconnection of the ground wire is considered as one factor, and an abnormality is detected. It is possible to detect. However, no communication line is provided in a section of the charging cable between the protection device and the distribution board. For this reason, in this section, the disconnection of the ground wire cannot be detected from the automobile, and if the ground wire is disconnected in the section, there is a risk of causing an electric shock accident.

In addition, as a method for detecting the disconnection of the ground wire, a method (Patent Document 1) for confirming the presence or absence of the disconnection by transmitting a pulse signal to the ground wire at regular intervals is also conceivable. However, since this method depends on the grounding environment, it is necessary to measure and adjust the grounding resistance, which requires work by an expert and requires a complicated and expensive detection device.
JP-A-8-293374

  Accordingly, an object of the present invention is to provide a low-cost disconnection detection circuit that can easily detect a disconnection of a ground wire incorporated in an automobile charging system without using a communication line. Another object of the present invention is to provide a ground wire breakage detection circuit that can be shared during both 100V charging and 200V charging.

  The present invention, which has been made to solve the above problems, is a disconnection detection circuit for a ground wire of a vehicle charging system including a first power wire, a second power wire, and a ground wire. A first detection circuit for detecting a line voltage between the first power supply line and a second detection circuit for detecting a line voltage between the ground line and the second power supply line. A voltage resistor is provided, and a diode is interposed between each voltage dividing resistor and the power supply line. The disconnection detection circuit can be incorporated in the middle of the charging cable or in the charging box.

  According to a third aspect of the present invention, there is provided a disconnection detection circuit according to the present invention, which is a disconnection detection circuit for a ground wire of an automotive charging system including a first power supply line, a second power supply line, and a ground wire. The detection circuit includes a detection circuit that detects a line voltage between the ground line and the first power supply line. The detection circuit includes a voltage dividing resistor and a diode interposed between the voltage dividing resistor and the power supply line. It may be.

  According to the ground wire breakage detection circuit of the vehicle charging system of the present invention, the same potential difference appears at the detection point even when the power supply voltage is different. Therefore, the ground wire breakage can be easily and accurately performed at both 100V charge and 200V charge. Can be detected. In addition, by interposing a diode between each voltage dividing resistor and the power supply line, it is possible to prevent the line voltage from flowing into the detection circuit when the ground line is disconnected. Since the circuit of the present invention is small and inexpensive, it can be incorporated in a charging cable for automobiles, and is effective in preventing an electric shock accident due to disconnection of the ground wire.

  According to a third aspect of the present invention, there is provided a disconnection detection circuit according to the present invention, which is a disconnection detection circuit for a ground wire of an automotive charging system including a first power supply line, a second power supply line, and a ground wire. The detection circuit includes a detection circuit that detects a line voltage between the ground line and the first power supply line. The detection circuit includes a voltage dividing resistor and a diode interposed between the voltage dividing resistor and the power supply line. As a result, the disconnection of the ground wire can be detected with a very simple configuration.

Preferred embodiments of the present invention are shown below.
In FIG. 1, 1 is a distribution board, 2 is a charging box connected to the secondary side of this distribution board 1, 3 is a charging cable for automobiles, and 4 is an electric vehicle. At the time of charging, the tip of the automobile charging cable 3 is connected to the power receiving connector 5 of the electric vehicle 4. A protection device 6 is attached in the middle of the automobile charging cable 3. Inside the protective device 6, a leakage detecting unit 7 and an opening / closing control unit 9 for the contact 8 are accommodated. The vehicle charging system means a series of charging systems from the distribution board 1 through the charging box 2 to the electric vehicle 4 through the vehicle charging cable 3.

  In order to send an open / close signal from the electric vehicle 4 to the open / close control unit 9, a communication line 10 is incorporated on the distal end side of the protection device 6 of the automotive charging cable 3. In addition, a first power line 11, a second power line 12, and a ground line 13 are incorporated inside the automobile charging cable 3. In the case of 100V charging, the first power supply line 11 and the second power supply line 12 are connected to the L1 phase and the N phase on the secondary side of the distribution board 1, and in the case of 200V charging, The power supply line 11 and the second power supply line 12 are connected to the L1 phase and the L2 phase on the secondary side of the distribution board 1. In addition, a breakage detection circuit 14 and a breakage determination circuit 15 according to the present invention are housed in the protective device 6. The details will be described below with reference to FIG.

  As shown in FIG. 2, the disconnection detection circuit 14 according to the present invention includes a first detection circuit 16 and a second detection circuit 17. In the first detection circuit 16, a diode 18, a first voltage dividing resistor 19, and a second voltage dividing resistor 20 are connected in series between the first power supply line 11 and the ground line 13. The second detection circuit 17 includes a diode 21, a third voltage dividing resistor 22, and a fourth voltage dividing resistor 23 connected in series between the second power supply line 12 and the ground line 13. Both detection circuits 16 and 17 are connected in parallel to the ground wire 13. The diode 18 and the diode 21 are in the same direction as shown in FIG. The intermediate points of the voltage dividing resistors are set as detection points A and B, and the voltage detected at these points (potential difference from the ground wire 13) is output to the disconnection determination circuit 15.

  In this embodiment, the phase of the second power supply line 12 changes between 100 V charging and 200 V charging, but the resistance values of the first voltage dividing resistor 19 and the second voltage dividing resistor 20 are as follows. The resistance values of the third voltage dividing resistor 22 and the fourth voltage dividing resistor 23 may be the same. The operation of this circuit will be described below.

  First, in the case of 100V charging, as described above, the first power supply line 11 is connected to the L1 phase, and the second power supply line 12 is connected to the N phase. If the ground wire 13 is healthy in this state, 100 V, which is the ground voltage of the L1 phase, is applied to both ends of the first detection circuit 16, and at the detection point A, a constant voltage (for example, 1 V) determined by the resistance voltage dividing ratio. ) Is detected. However, when the ground wire 13 is disconnected, no current flows through the first detection circuit 16 due to the action of the diode 18 and the diode 21, and therefore zero V is detected at the detection point A. Thus, in the case of 100V charge, the presence or absence of the disconnection of the ground wire 13 can be detected depending on whether the detection voltage at the detection point A is a constant voltage or zero. When the disconnection determination circuit 15 determines that the disconnection has occurred, the open / close control unit 9 opens the contact 8 to prohibit or stop charging. In the case of 100 V charging, the ground voltage of the second power supply line 12 connected to the N phase is zero V, so that the voltage at the point B of the second detection circuit 17 even if the ground line 13 is healthy. Is zero.

  When the connection between the power supply line 11 and the power supply line 12 is reversed in the distribution board, a constant voltage at normal time appears at the detection point B, and the voltage at the detection point A becomes zero. Therefore, in the case of 100V charge, it is determined that there is an abnormality when both voltages at the detection points A and B become zero. Further, the element of the disconnection determination circuit 15 at the detection point A and the element of the disconnection determination circuit 15 at the detection point B can have exactly the same configuration.

  Next, in the case of 200V charging, as described above, the first power supply line 11 is connected to the L1 phase, and the second power supply line 12 is connected to the L2 phase. If the ground wire 13 is healthy in this state, 100 V, which is the ground voltage of the L1 phase, is applied to both ends of the first detection circuit 16 as in the case of 100 V charge. A fixed constant voltage (for example, 1 V) is detected. In addition, 100 V, which is an L2 phase ground voltage, is applied to both ends of the second detection circuit 17, and a constant voltage determined by the resistance voltage division ratio is detected at the detection point B. As described above, if the resistance values of the first voltage dividing resistor 19 and the second voltage dividing resistor 20 are set to be the same as the resistance values of the third voltage dividing resistor 22 and the fourth voltage dividing resistor 23, the detection point B is also 1 V, for example. ) Is detected.

  Thus, since the ground voltage of the L1 phase and the ground voltage of the L2 phase are both constant values of 100 V, the same constant voltage is detected at both the detection point A and the detection point B if the ground wire 13 is healthy. . When the ground wire 13 is broken, no current flows through any of the detection circuits due to the action of the diode 18 and the diode 21, so that the detection voltage is 0 V at both the detection point A and the detection point B. For this reason, the disconnection of the ground wire 13 can be detected easily and accurately based on the detection voltages at the detection points A and B. When the disconnection determination circuit 15 determines that the disconnection has occurred, the switching control unit 9 opens the contact 8. To prohibit or stop charging. The determination of disconnection may be performed when the detection voltages at detection points A and B are both 0V. Therefore, the same disconnection detection circuit 15 can be used even when power is supplied at 200 V, and the common charging cable 3 can be used only by converting the shape of the connector connected to the charging box 2 with an adapter or the like. It becomes possible.

  When the diodes 18 and 21 are omitted, a line voltage sneak occurs between the first detection circuit 16 and the second detection circuits 17 and 18, and the above-described effects of the present invention can be obtained. Can not be.

  As described above, according to the detection circuit of the present invention, the disconnection of the ground wire 13 can be detected easily and accurately. In addition, in both the case of 100V charging and the case of 200V charging, switching of the detection circuit is unnecessary, and it is determined that the ground wire 13 is disconnected when both of the detection voltages at the detection points A and B are 0V. It is possible to process according to the criteria.

  In the above-described embodiment, the protection device 6 is installed in the middle of the charging cable 3 and the detection circuit 14 is incorporated therein. However, the protection device 6 may be incorporated in the charging box 2. In this case, the ground wire breakage detection circuit according to the present invention includes an internal ground wire incorporated in the connection line 24 from the charging box to the distribution board, and an earth wire from the ground terminal of the distribution board to the ground. This is to detect disconnection. In other words, in the above embodiment, the vehicle charging system detects the disconnection of the ground wire of the vehicle charging system from the distribution board 1 to the protection device 6 via the charging box 2.

  As shown in FIG. 3, the disconnection detection circuit 16 for the ground wire of the automobile charging cable including the first power line 11, the second power line 12, and the ground line 13 includes the ground line and the first power source. Only the line voltage to the line may be detected. In this case, a disconnection determination circuit that determines that a disconnection has occurred when the voltage at the detection point A becomes zero may be provided. As a result, the disconnection of the ground wire can be detected with a very simple configuration.

1 is an overall view showing a preferred embodiment of the present invention. It is a circuit diagram which shows the principal part of this invention. It is a circuit diagram which shows the principal part of embodiment of invention of Claim 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Distribution board 2 Charging box 3 Car charging cable 4 Electric vehicle 5 Power receiving connector 6 Protection device 7 Leakage detection part 8 Contact 9 Opening / closing control part 10 Communication line 11 1st power supply line 12 2nd power supply line 13 Grounding line 14 Disconnection detection circuit 15 Disconnection determination circuit 16 First detection circuit 17 Second detection circuit 18 Diode 19 First voltage dividing resistor 20 Second voltage dividing resistor 21 Diode 22 Third voltage dividing resistor 23 Fourth voltage dividing resistor 24 Connection line

Claims (3)

A disconnection detection circuit for a ground wire of a vehicle charging system including a first power wire, a second power wire, and a ground wire,
A first detection circuit for detecting a line voltage between the ground line and the first power line; and a second detection circuit for detecting a line voltage between the ground line and the second power line.
These detection circuits have voltage divider resistors,
A ground wire disconnection detection circuit for an automotive charging system, wherein a diode is interposed between each voltage dividing resistor and the power supply line.   The disconnection detection circuit for a grounding wire in a vehicle charging system according to claim 1, wherein the disconnection detection circuit is incorporated in the middle of the charging cable or in the charging box. A disconnection detection circuit for a ground wire of a vehicle charging system including a first power wire, a second power wire, and a ground wire,
The disconnection detection circuit comprises a detection circuit for detecting a line voltage between the ground line and the first power supply line,
The detection circuit comprises a voltage dividing resistor and a diode interposed between the voltage dividing resistor and a power supply line.

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