JP2003324801A - Method of connecting power source in electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of connecting a power source in an electric vehicle which prevents the fault in a connection circuit between a battery and electric load from occurring, when precharging a smoothing capacitor installed in the electric load. <P>SOLUTION: A controller 42 performs the precharge treatment for charging the smoothing capacitor 21 installed in the electric load 3, by closing a first opening and closing contact 31 after closing a third opening and closing contact 33 in the first place, when connecting a fuel cell 2 with the electric load 3; and after the finishing of that precharge treatment, the controller 42 opens the third opening and closing contact 33 and also closes a second opening and closing contact 32, thereby connecting the fuel cell 2 with the electric load 3. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting a battery and an electric load provided in an electric vehicle.

[0002]

2. Description of the Related Art In an electric vehicle such as a fuel cell having a high output voltage as a drive source, an electric load operated by the fuel cell and electric power supplied from the fuel cell is isolated from the vehicle body. It is installed (floating).

FIG. 2A shows a circuit configuration for connecting a fuel cell 50 and an electric load 51, which are provided so as to be insulated from the vehicle body of an electric vehicle, and shows a cell 52 of the fuel cell 50. A capacitance of 5 is provided between the positive electrode 53 and the vehicle body BE.
5 exists, and the electrostatic capacitance 56 exists between the negative electrode 56 and the vehicle body ground BE.

In addition to the load resistor 60 that consumes electric power, the electric load 51 is provided with a smoothing capacitor 61 between the positive power supply line 64 and the negative power supply line 64. An electrostatic capacitance 62 exists between the vehicle body ground BE, and an electrostatic capacitance 63 exists between the negative power line 65 and the vehicle body ground BE.

Then, in order to connect the fuel cell 50 and the electric load 51, switching contacts 70, 71, 73, 74,
A controller 80 for controlling the operation of these open / close contacts is provided. The switching contacts 70 and 71 are the fuel cell 50.
And the electric load 51 are directly connected to each other. The two-contact relay is provided to open and close at the same time. On the other hand, switching contact 7
3 and 74 are smoothing capacitors 6 provided in the electric load 51.
It is for precharging 1, and is equipped with a two-contact relay to open and close at the same time.

Here, when connecting the fuel cell 50 and the electric load 51, if the opening / closing contacts 70 and 71 are suddenly closed, an excessive charging current flows from the fuel cell 50 to the smoothing capacitor 61, and the opening / closing contact 70 is welded. May occur. Therefore, the controller 80 first sets the open / close contact 7
3, 74 are closed, and a charging current is supplied from the positive electrode 53 of the fuel cell 50 to the smoothing capacitor 61 via the current limiting resistor 72 so that the smoothing capacitor 61 is precharged.

After charging the smoothing capacitor 61, the switching contacts 70 and 71 are closed and the switching contact 7 is closed.
By opening 3, 74 and directly connecting the fuel cell 50 and the electric load 51, an excessive charging current is prevented from flowing to the smoothing capacitor 61.

However, when the smoothing capacitor 61 is precharged by the circuit configuration shown in FIG.
An excessive current may flow through the switching contact 74, causing damage to the switching contact 74.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and when a smoothing capacitor provided in an electric load is precharged, a failure of a switching contact that connects a battery and an electric load. It is an object of the present invention to provide a power supply connection method in an electric vehicle that prevents the occurrence of the above.

[0010]

DISCLOSURE OF THE INVENTION As a result of investigating and studying the cause of the breakage of the switching contact 74 shown in FIG. 2A, the inventors of the present application have mainly prepared a two-contact relay for mechanical reasons. When the closing timings of the opened and closed contacts 73 and 74 are deviated, when the opening and closing contacts 73 and 74 are closed to precharge the smoothing capacitor 61, the opening and closing contact 74 is closed before the opening and closing contact 73. It was clarified that an excessive current flows through the switching contact 74 to cause welding or the like of the switching contact 74 when it is formed.

Specifically, the reason why an excessive current flows through the switching contact 74 is that the electrostatic capacity existing in the fuel cell 50 when only the switching contact 74 is closed with reference to FIG. 2B. A closed circuit from 56 to the negative electrode 54 of the fuel cell 50 is formed via the vehicle body earth BE, the electrostatic capacity 63 existing in the electric load 51, the negative power line 65 of the electric load 51, and the opening / closing contact 74. Therefore, it is considered that the electric charge charged in the electrostatic capacitance 56 flows to the opening / closing contact 74 and welding of the opening / closing contact 74 occurs.

Therefore, the power supply connection method for an electric vehicle according to the present invention comprises a battery insulated from the vehicle body and an electric load insulated from the vehicle body and having a smoothing capacitor connected between the DC power supply lines. A method of connecting the battery and the electric load in an electric vehicle provided, wherein the positive electrode of the battery is connected to a power line on the positive side of the electric load via a current limiting resistor, The negative electrode is connected to the negative power source line of the electric load, and the smoothing capacitor is charged by the current supplied from the positive electrode of the battery to the positive power source line of the electric load via the current limiting resistor. After the precharge process and the end of the precharge process, the negative electrode of the battery is connected to the negative power source line of the electric load, and the positive electrode of the battery is bypassed through the current limiting resistor. Performing a direct process of connecting the power supply line of the positive side of the electrical load, characterized by connecting the electrical load and the battery.

According to the present invention, in the precharge process, first, the positive electrode of the battery is connected to the positive power source line of the electric load through the current limiting resistor, whereby the positive electrode of the battery is connected. The electric charge charged in the capacitance between the vehicle bodies flows into the capacitance between the power lines on the positive side of the electric load via the current limiting resistor, but the current flowing is limited by the current limiting resistor. Therefore, an excessive current does not flow into the connection circuit and the connection circuit is not damaged. Then, next, the negative electrode of the battery is connected to the negative power source line of the electric load, whereby the smoothing capacitor can be charged by the current limited by the current limiting resistor.

In the electric vehicle, a power supply voltage detecting means for detecting a voltage between positive and negative power supply lines of the electric load, and conduction / interruption between a negative electrode of the battery and a negative power supply line of the electric load. First switching means for switching, and continuity / between the positive electrode of the battery and the power line on the positive side of the electric load.
A second opening / closing means for switching the cutoff, a series circuit including a third opening / closing means connected in parallel with the second opening / closing means, and a current limiting resistor are provided, and the precharge process is performed by the third opening / closing means. When the first opening / closing means is closed and then the first opening / closing means is closed, and then the direct connection process is performed by opening the third opening / closing means and closing the second opening / closing means. Can detect a failure of the first opening / closing means and the third opening / closing means.

That is, in the precharge process, when the detection voltage of the power supply voltage detecting means rises when the control for closing the third opening / closing means is performed, the first opening / closing means is already closed. It can be determined that the charging of the smoothing capacitor has started in the state of being formed. Therefore, in this case, the failure detection means can determine that the first opening / closing means is in the closed failure state.

Further, in the precharge process, when the detection voltage of the power supply voltage detecting means does not rise when the control for closing the first opening / closing means is performed, the first opening / closing means and the above-mentioned It can be determined that at least one of the third opening / closing means is in the open circuit failure state, and therefore the smoothing capacitor is not charged. Therefore, in this case, the failure detection means can determine that at least one of the first opening / closing means and the third opening / closing means is in the open failure state.

Further, when the electric vehicle is provided with a battery voltage detecting means for detecting the output voltage of the battery, it is possible to detect a failure of the second opening / closing means.

That is, in the direct connection process, when the detection voltage of the power supply voltage detecting means and the detection voltage of the battery voltage detecting means are different when the control for closing the second opening / closing means is performed, the second voltage is detected. It can be determined that the positive electrode of the battery and the positive-side power supply line of the electric load are not electrically connected to each other because the opening / closing means is in the open failure state. Therefore, in this case, it can be determined that the second opening / closing means is in the open failure state.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a circuit configuration diagram of a power supply connection device that connects a fuel cell and an electric load included in an electric vehicle.

Referring to FIG. 3, a power supply connection device 1 for an electric vehicle (hereinafter, simply referred to as power supply connection device 1) is mounted on an electric vehicle driven by a fuel cell 2 (corresponding to a battery of the present invention). Then, the fuel cell 2 and the electric load 3 (electrical auxiliary equipment such as an air conditioner) are connected and disconnected.

The fuel cell 2 and the electric load 3 are provided so as to be insulated from the vehicle body of the electric vehicle. Therefore, the capacitance 13 is provided between the positive electrode 11 of the fuel cell unit 10 and the vehicle body BE.
Exists, the negative electrode 12 of the fuel cell 10 and the vehicle body ground B
The capacitance 14 also exists between E. The electric load 3 also has a capacitance 22 between the positive power line 24 and the vehicle body ground BE, and the negative power line 25 and the vehicle ground B.
There is a capacitance 23 between E. Further, between the positive side power line 24 and the negative side power line 25 of the electric load 3,
A smoothing capacitor 21 for suppressing fluctuations in power supply voltage is provided.

Here, if the fuel cell 2 and the electric load 3 are constantly connected, a leak current flows from the fuel cell to the electric load 3 even when the electric load 3 is not operating, and wasteful current is consumed. It Therefore, when the electric load is not operating, the fuel cell 2 and the electric load 3 are cut off to prevent a leakage current from flowing, and the fuel cell 2 and the electric load 3 are connected only when the electric load 3 is operated. Therefore, the power supply connection device 1 is provided.

The power supply connection device 1 includes a negative electrode 12 of the fuel cell 2.
And a first opening / closing contact 31 (corresponding to a first opening / closing means of the present invention) for connecting / disconnecting between the negative side power supply line 25 of the electric load 3 and the positive side of the positive electrode 11 of the fuel cell 2 and the electric load 3. Second open / close contact 32 for connecting / disconnecting between the power supply lines 24 of
A third opening / closing contact 33 (corresponding to the second opening / closing means of the present invention) for connecting the positive electrode 11 of the fuel cell 2 and the positive power supply line 24 of the electric load 3 via the current limiting resistor 34 (Corresponding to the third opening / closing means of the invention), a battery voltage detector 40 for detecting the output voltage of the fuel cell 2 (corresponding to the battery voltage detecting means of the invention), and positive and negative power supply lines 24 of the electric load 3, Power supply voltage detector 41 for detecting voltage between 25
(Corresponding to the power supply voltage detecting means of the present invention).

Then, the first opening / closing contact 31 and the second opening / closing contact 3 are controlled by a control signal output from the controller 42 composed of a microcomputer, a memory and the like.
The open / closed states of the second and third open / close contacts 33 are switched, and the voltage detection signals of the battery voltage detector 40 and the power supply voltage detector 41 are input to the controller 42.

The first opening / closing contact 31, the second opening / closing contact 32, and the third opening / closing contact 33 are mechanical contacts provided in separate relays, and the drive coil of each relay is energized. It opens when the drive coil is closed, and opens when the power supply to the drive coil is cut off. And the controller 4
2 is a first switching contact 31 and a second
The open / close state of the open / close contact and the open / close state of the third open / close contact are independently switched.

Next, the fuel cell 2 is controlled by the controller 42.
The procedure for connecting the electric resistor 3 and the electric resistor 3 will be described.

When the fuel cell 2 is connected to the electric resistance 3 and the electric resistance 3 is operated, the first opening / closing contact 31 and the second opening / closing contact 32 are immediately closed, and the fuel cell 2 and the electric resistance 3 are connected. Is directly connected, an excessive current flows from the positive electrode 11 of the fuel cell 2 through the second opening / closing contact 32 to the smoothing capacitor 21 having a low impedance, and welding or the like occurs in the second opening / closing means 32. The open / close contact 32 fails.

Therefore, the controller 42 first performs a precharge process for charging the smoothing capacitor 21 and then performs a direct connection process for directly connecting the fuel cell 2 and the electric load 3 so that the electric load 3 is changed from the fuel cell 2 to the electric load 3. It prevents the flow of excessive current.

In the precharge process, the controller 42 first closes the third opening / closing contact 33. As a result, from the positive electrode 11 of the fuel cell 2 to the current limiting resistor 34,
A current flows through the positive side electrostatic quantity 22, the vehicle body BE, and the electrostatic capacity 14 on the negative electrode 12 side of the fuel cell 2, but since this current is limited by the current limiting resistor 34, an excessive current is generated. There is no flow through the third opening / closing contact 33, and no failure such as welding of the third opening / closing contact 33 occurs.
In addition, by the third switching contact 33 and the current limiting resistor,
A series circuit of the present invention is constructed.

Then, the controller 42,
The open / close contact 31 is closed, whereby the smoothing capacitor 21 is charged by the current supplied from the positive electrode 11 of the fuel cell 2 through the current limiting resistor 34.

Here, in the time interval from the closing of the third opening / closing contact 33 to the closing of the first opening / closing contact 31, the electric charges charged in the electrostatic capacitances 14 and 23 are discharged. Is set to 0.5 to 1.0 seconds, for example.

When the controller 42 detects the completion of charging of the smoothing capacitor 21 from the voltage detected by the power supply voltage device 41, the precharge process is terminated, the third opening / closing contact 33 is opened, and the second opening / closing contact 32 is opened. After closing, a direct connection process is performed in which the fuel cell 2 and the electric load 3 are directly connected (without a current limiting resistor).

By performing the precharge process and the direct connection process described above, when the fuel cell 2 and the electric load 3 are connected, an excessive current flows from the fuel cell 2 to the electric load 3 and the electric current flows in the current path. It is possible to prevent a failure from occurring.

Further, the controller 42 uses the first opening / closing contact 3 in the above-mentioned precharge process and direct connection process.
The failure detection of the first, second switching contacts 32, and the third switching contacts 33 is performed.

First, in the precharge process, the controller 42 confirms whether or not the detection voltage of the power supply voltage detector 41 rises when the third switching contact 33 is closed.
When the first opening / closing contact 31 is in the open state when the third opening / closing contact 33 is closed, the smoothing capacitor 21 is not charged and the detection voltage of the power supply voltage detector 41 does not rise.

On the other hand, when the third opening / closing contact 33 is closed and the first opening / closing contact 31 is in the closing failure state, the smoothing capacitor 21 is charged, so that the detection voltage of the power supply voltage detector 41 is detected. Rises. Therefore, when the controller 42 detects a rise in the detection voltage of the power supply voltage detector 41, the controller 42 determines that the first open / close contact 31 is in the closed failure state and issues a failure notification (error display or buzzer display on the driver's seat). Sounding).

In the precharge process, the controller 42 closes the third opening contact 33 and then closes the first opening contact 31. Then, the power supply voltage detector 41 is closed.
Check if the detection voltage of has risen. Controller 42
Outputs a control signal for closing the first opening / closing contact 31 and the third opening / closing contact 33, the first opening / closing contact 31 and the third opening / closing contact 31
If the switching contacts 33 of both are normally operated and closed, the smoothing capacitor 21 is charged, so that the power supply voltage detector 4
The detection voltage of 1 rises.

On the other hand, when at least one of the first open / close contact 31 and the third open / close contact 33 is in the open circuit failure state, the smoothing capacitor 21 is not charged, and the detection voltage of the power supply voltage detector 41 rises. do not do. Therefore, when the controller 42 detects a rise in the detection voltage of the power supply voltage detector 41, the controller 42 determines that at least one of the first opening / closing contact 31 and the third opening / closing contact 33 is in the open failure state. Then, the failure is notified.

In the direct connection process described above, the controller 42 opens the third open / close contact and closes the second open / close contact 32 to detect the voltage (V1) of the battery voltage detector 40 and the power source. It is confirmed whether the detection voltage (V2) of the voltage detector 41 becomes equal.

When the controller 42 outputs a control signal for closing the second opening / closing contact 32, the second opening / closing contact 3
When 2 operates normally and is in the closed state, the first open contact 31 is already in the closed state, so the positive and negative terminals of the battery voltage detector 40 and the power supply voltage detector 41. Since the two are brought into conduction, the detection voltage (V1) of the battery voltage detector 40 and the detection voltage (V2) of the power supply voltage detector 41 become equal.

On the other hand, when the second open / close contact 32 is in the open failure state, the battery voltage detector 40 and the power supply voltage detector 4
Since the positive terminal of 1 does not become conductive, the detection voltage (V1) of the battery voltage detector 40 and the detector (V2) of the power supply voltage detector 41 are not equal. Therefore, when the detected voltage (V1) of the battery voltage detector 40 and the detected voltage (V2) of the power supply voltage detector 41 are different, the controller 42 determines that the second opening / closing contact 32 is in the open failure state. Issue a failure notification.

In the present embodiment, the fuel cell is shown as the battery of the present invention, but in the case of connecting the electric load to the battery mounted insulated from the vehicle body of the electric vehicle,
The present invention can be applied to other types of batteries.

In the present embodiment, the relay contacts are used as the first opening / closing means, the second opening / closing means, and the third opening / closing means of the present invention, but a contactless opening / closing means such as a transistor or FET is used. Even when using, the present invention can be applied.

Further, in the present embodiment, in the above-described precharge process and direct connection process, the process of detecting the presence or absence of a failure of the switching contact is performed, but even if the process is not performed, the present invention is performed. The effect can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a power supply connection device of the present invention for connecting a fuel cell provided in an electric vehicle and an electric load.

FIG. 2 is a circuit configuration diagram of a conventional power supply connection device for connecting a fuel cell provided in an electric vehicle and an electric load.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electric vehicle power supply connection device, 2 ... Fuel cell, 3 ... Electric load, 11 ... Fuel cell positive electrode, 12 ... Fuel cell negative electrode, 13, 14 ... Fuel cell electrostatic capacity, 21 ... Smoothing capacitor, 22 , 23 ... Capacitance of electric load, 24 ... Power line on positive side of electric load, 25 ... Power line on negative side of electric load, 31 ... First opening / closing contact, 32 ... Second opening / closing contact, 33 ... Third open / close contact, 34 ... Current limiting resistor, 4
0 ... Battery voltage detector, 41 ... Power supply voltage detector, 42 ... Controller

Claims (4)

[Claims] 1. An electric vehicle comprising a battery insulated from a vehicle body and an electric load insulated from the vehicle body and having a smoothing capacitor connected between DC power supply lines, the battery and the electric vehicle being provided. A method of connecting to a load, wherein the positive electrode of the battery is connected to a positive power source line of the electric load via a current limiting resistor, and then the negative electrode of the battery is negative power source line of the electric load. And a precharge process for charging the smoothing capacitor with a current supplied from the positive electrode of the battery to the positive side power supply line of the electric load via the current limiting resistor, and the precharge process ends. Then, a direct connection process in which the negative electrode of the battery is connected to the negative power source line of the electric load, and the positive electrode of the battery is connected to the positive power source line of the electric load without the current limiting resistor. Performing bets, power connection method in an electric vehicle, characterized in that for connecting the battery and the electrical load. 2. The electric vehicle includes a power supply voltage detecting means for detecting a voltage between positive and negative power supply lines of the electric load, and conduction / interruption between a negative electrode of the battery and a negative power supply line of the electric load. A first opening / closing means for switching, a second opening / closing means for switching conduction / interruption between the positive electrode of the battery and a positive power supply line of the electric load, and a third opening / closing means connected in parallel with the second opening / closing means. And a series circuit including a current limiting resistor, the pre-charge processing is performed by closing the first opening / closing means after closing the third opening / closing means, and then performing the direct connection. The processing is performed by opening the third opening / closing means and closing the second opening / closing means, and in the precharge processing, when the control for closing the third opening / closing means is performed, the power supply voltage is The detection voltage of the detection means has increased Kiniwa, said power supply connection in an electric vehicle according to claim 1, wherein the first opening and closing means, characterized in that determined to be closing failure. 3. The electric vehicle includes power supply voltage detecting means for detecting a voltage between positive and negative power supply lines of the electric load, and conduction / interruption between a negative electrode of the battery and a negative power supply line of the electric load. A first opening / closing means for switching, a second opening / closing means for switching conduction / interruption between the positive electrode of the battery and a positive power supply line of the electric load, and a third opening / closing means connected in parallel with the second opening / closing means. And a series circuit including a current limiting resistor, the pre-charge processing is performed by closing the first opening / closing means after closing the third opening / closing means, and then performing the direct connection. The processing is performed by opening the third opening / closing means and closing the second opening / closing means, and in the precharge processing, the power supply voltage is set when the control for closing the first opening / closing means is performed. Is the detection voltage of the detection means rising? When the can, according to claim 1, characterized in that it is determined that at least one is open failure of said first switching means and said third switching means
A method for connecting a power source in the electric vehicle described. 4. The electric vehicle includes a power supply voltage detecting means for detecting a voltage between positive and negative power supply lines of the electric load, a battery voltage detecting means for detecting an output voltage of the battery, a negative electrode of the battery, and the battery. First opening / closing means for switching between conduction / interruption between the negative power supply line of the electric load, and second opening / closing means for switching between conduction / interruption between the positive electrode of the battery and the positive power supply line of the electric load, A series circuit including a third opening / closing means connected in parallel with the second opening / closing means and a current limiting resistor, wherein the precharge process is performed after closing the third opening / closing means. After opening and closing the opening and closing means, the direct connection processing is performed by opening the third opening and closing means and closing the second opening and closing means, and in the direct connection processing, the second opening and closing means. When the control to close the The electric vehicle according to claim 1, wherein when the detected voltage of the power supply voltage detecting means and the detected voltage of the battery voltage detecting means are different from each other, it is determined that the second opening / closing means has an open failure. Power connection method.