JP2007157631A - Fuel cell system, fuel cell vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To identify a detailed leaking part when a ground fault is detected in a fuel cell system. <P>SOLUTION: In a fuel cell vehicle 10, power generated by a fuel cell 20 is supplied to a high-voltage component such as an air conditioner 40 and an air compressor 50. Further, the intermediate potential of a terminal 30 of the fuel cell 20 is grounded to a body 12 through resistors 102, 104. A ground fault detector 100 detects that the leakage of a current has occurred in one of a plurality of the high-voltage components based on a leaking current flowing in this route. Then, a component identification part 112 isolates each high-voltage component temporarily from the circuit by carrying out in order the separation and the connection of relays 42, 52, ..., when the ground fault detector detects the leakage of the current. Then, it identifies the isolated high-voltage component as a leaking source based on whether or not leakage is detected during this time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a system using a fuel cell, and more particularly to a technique for detecting leakage in this system.

  In a fuel cell system that supplies power generated by a fuel cell to an electrical component (device), it is desirable to detect the presence or absence of electric leakage to ensure safety.

  Patent Document 1 below discloses a technique for detecting electric leakage in a fuel cell vehicle or the like. Here, the intermediate potential of the fuel cell is grounded, and leakage detection is performed based on the leakage current flowing through this connection path.

JP 2004-55384 A

  In order to inspect and repair the location of leakage, it is necessary to identify the location of leakage. However, the technique of the above-mentioned Patent Document 1 does not specify the location of electric leakage. In addition, in a fuel cell vehicle equipped with a fuel cell system, it is inconvenient that it is not possible to run on its own to a repair shop if it immediately prohibits traveling when a leakage occurs. In other words, if safety can be ensured, it can be said that it is desirable that the operation of the fuel cell system can be continued.

  An object of the present invention is to establish a new technique for identifying a leakage point in a fuel cell system.

  An object of the present invention is to enable operation of a fuel cell system within a range in which safety can be confirmed when a leakage occurs.

  The fuel cell system according to the present invention includes a fuel cell that generates electric power, a plurality of electric components to which electric power generated by the fuel cell is supplied, and that leakage has occurred in any of the plurality of electric components. The leakage detector that detects the leakage based on the leakage current that accompanies the leakage, and when the leakage detector detects a leakage, this leakage detector is used to determine which portion of the electrical components has the leakage. Specifying means for specifying.

  A fuel cell is a device that generates electricity by chemically reacting an anode gas (for example, hydrogen) and a cathode gas (for example, oxygen) and taking out electric power in the process. The electric power generated by the fuel cell is supplied to a plurality of electric components, that is, devices using electricity, and used for its operation. Of course, the electrical component may operate at a relatively low voltage. However, considering the usefulness of countermeasures against electric leakage, it can be said that it is more appropriate to target high-voltage components that operate at a relatively high voltage. The relatively high voltage means a voltage of at least about 50 V, typically a voltage of about 100 V or more, from the viewpoint of safety during leakage. That is, for example, the voltage of the auxiliary power supply system (configured by a 12V battery and a DC / DC converter or the like) normally mounted on the vehicle is out of scope here. Further, from the viewpoint of the output of the fuel cell as a reference, the electrical component to which the output voltage of the fuel cell is directly applied, the electrical component to be applied by being boosted, or the voltage is not reduced so much (for example, the output voltage An electric component that is applied (50% or more, at least 20% or more of the output voltage) may be called a high-voltage component.

  The leakage detector is a device that detects a leakage of an electrical component based on a leakage current. That is, the leakage is detected based on the detection of the leakage current or the detection of an electromagnetic phenomenon such as a change in voltage or magnetic field associated with the leakage current. Moreover, this leakage detector is not provided for every electric component, but can monitor the occurrence of electric leakage in any part of a plurality of electric components. In the fuel cell system, one leakage detector is typically provided, but two or more may be provided. In addition, electric leakage means the electricity supply to the location which should not flow originally. Specific examples of energization include an example in which current leaks through water applied to the circuit, an example in which insulation breaks due to deterioration of the insulation member, or an example in which electrical components abnormally increase in voltage and insulation breaks and current leaks. Can be mentioned.

  The specifying means specifies in which part of the plurality of electrical components the leakage has occurred when the leakage detector detects the leakage. Identifying which part of a plurality of electrical components is, for example, identifying one or more electrical components that actually caused a leakage, or in one or more electrical components that actually caused a leakage Furthermore, specifying a detailed location, specifying an electrical component group including an electrical component that has actually caused a leakage and an electrical component that has not caused a leakage, and including a leakage occurrence location as a whole, It can be exemplified that the location is specified. A leakage detector is used to identify the leakage site by the specifying means. It can be used in various ways. For example, for the leakage current when the leakage detector detects leakage, the value of current, voltage, magnetic field, etc. and time change information are obtained. An example of comparing with a leakage test result performed and recorded in advance, or comparing with information on abnormal operation at the leakage time of each electrical component can be considered. It is also effective to limit the amount of power supplied to the electrical components (stop or reduce) and let the leak detector detect the leak again and analyze the result after the leak detector first detects the leak. I will.

  According to this configuration, when the leakage detector detects a leakage, it is possible to specify a leakage portion in a narrower range than the electrical component that is detected by the leakage detector. As a result, there is an advantage that the inspection and repair of leakage can be facilitated. In addition, it is possible to determine how serious the leakage point is for the system and to disconnect the leakage point. The information on the identified leakage point may be stored in a memory or transmitted to a user as necessary.

  Note that the processing by the specifying unit may be performed immediately upon detection of a leakage, but may be performed after waiting for an appropriate timing when urgent is not required. In particular, when the processing by the specifying unit makes the normal operation of the fuel cell system impossible, the system state is set to the specific processing mode for performing the processing by the specifying unit instead of the normal operation mode. There is a need. Therefore, for example, when only a small leakage current in the allowable range is detected, the process may be shifted to the specific processing mode immediately before the fuel cell system is stopped or at the next startup. I will.

  In one aspect of the fuel cell system of the present invention, the fuel cell system includes a disconnecting unit that disconnects a part of the plurality of electrical components from the power supply line, and the specifying unit is configured to detect the leakage detector when the disconnecting unit performs disconnection. Based on whether or not the leakage is detected, it is specified in which part of the plurality of electrical components the leakage has occurred. The disconnecting means can be realized by, for example, an electromagnetic relay or a semiconductor switch. Further, in one aspect of the fuel cell system of the present invention, the disconnecting unit has a function of disconnecting each electrical component from the power supply line, and the specifying unit detects leakage when the disconnecting unit performs disconnection. Based on whether the leakage is detected by the device, it is specified in which electrical component the leakage has occurred.

  In one aspect of the fuel cell system of the present invention, the fuel cell has an intermediate potential connected to the ground via a resistor, and the leakage detector detects any of a plurality of electrical components based on the leakage current flowing through the resistor. Detects that a leakage has occurred between the ground and ground. In general, in a fuel cell, a large number of cells that generate low-voltage power are connected in series, thereby obtaining high-voltage power. The intermediate potential is a potential obtained between certain cells connected in series and is lower than the potential at the positive terminal of the fuel cell and higher than the potential at the negative terminal. The intermediate potential is an intermediate value between the potential of the positive terminal and the potential of the negative terminal or a value in the vicinity thereof (with the voltage width of the positive terminal and the negative terminal being 100%, for example, within 10% before and after the intermediate value) When used, it is particularly desirable because a large potential difference can be secured between both the positive terminal and the negative terminal. However, even when a potential greatly deviating from the intermediate value is adopted as the intermediate potential, a large potential difference from at least one of the terminals can be secured, which is sufficiently practical.

  In one aspect of the fuel cell system of the present invention, the fuel cell has an intermediate potential connected to the ground via a resistor, and the leakage detector detects any of a plurality of electrical components based on the leakage current flowing through the resistor. It is detected that a leakage has occurred between the ground and the ground, and the specifying means specifies in which part of the plurality of electrical components the leakage has occurred, based on the polarity of the leakage current. That is, based on the direction of the leakage current flowing through the resistor at the time of leakage, it is possible to specify information such as whether leakage has occurred in the circuit on the positive terminal side or whether leakage has occurred in the circuit on the negative terminal side.

  The fuel cell vehicle of the present invention is specified as an electric leakage portion by the fuel cell system, a vehicle equipped with the fuel cell system, a drive mechanism that drives the vehicle using the electric power generated by the fuel cell, and a specifying unit. Means for causing the vehicle to travel in a state where the electrical component is electrically disconnected when the electrical component is not indispensable for traveling of the vehicle. According to this configuration, even when electric leakage occurs in the fuel cell vehicle, the vehicle can travel within a range where safety can be confirmed. Examples of cases that are not indispensable for traveling include electrical components prepared in two or more systems, electrical components that are not used for traveling, and electrical components that are capable of traveling even though performance is degraded if not used for traveling. Note that when an electrical component is disconnected, the user (driver) may be informed that the electrical component cannot be used if necessary.

  FIG. 1 is a diagram schematically illustrating the configuration of a fuel cell vehicle 10 according to the present embodiment. The fuel cell vehicle 10 is obtained by mounting a fuel cell system on a vehicle including a vehicle body 12 and wheels 14. In the figure, general components for traveling the vehicle are omitted, and the components characteristic to the present embodiment are mainly described.

  The fuel cell vehicle 10 includes a fuel cell 20, an air conditioner 40, an air compressor 50, a power steering mechanism 60, a secondary battery 80, a leakage detector 100, and a control unit 110 as main components.

  The fuel cell 20 is provided with a large number of cells that are supplied with hydrogen and oxygen and take out low-voltage power using this chemical reaction. These cells are stacked in series to form two stacks 22 and 24, which are further connected in series. As a result, high-voltage power of about 400 V is obtained from the negative terminal 26 drawn from the negative stack 22 and the positive terminal 28 drawn from the positive stack 24. A terminal 30 for outputting the potential (referred to as an intermediate potential) is provided between the stacks 22 and 24. A negative line 32 and a positive line 34 are drawn out from the negative terminal 26 and the positive terminal 28, respectively. The negative line 32 and the positive line 34 supply power to various high-voltage components such as a vehicle running motor.

  The air conditioner 40, the air compressor 50, and the power steering mechanism 60 are high-voltage components that receive power supply from the negative line 32 and the positive line 34. Various other high-voltage components are mounted on the vehicle, but the three high-voltage components are shown here as representative examples. The air conditioner 40 is a device that air-conditions the interior of the fuel cell vehicle 10. In the air conditioner 40, a positive lead-in line 44 is connected to the positive line 34 and a negative lead-in line 46 is connected to the negative line 32 via a relay 42 that can be connected and disconnected. The positive lead-in line 44 and the negative lead-in line 46 are lines that constitute an electric circuit of the air conditioner 40, and thus, the high voltage power generated by the fuel cell 20 is supplied to the air conditioner 40.

  The air compressor 50 is a device that compresses air and supplies it to the cathode of the fuel cell 20. Similarly, for the air compressor 50, the positive lead-in line 54 and the negative lead-in line 56 are connected to the positive line 34 and the negative line 32 through the relay 52, respectively, and power is supplied. The power steering mechanism 60 is a device that amplifies the rotational force of the driver given to the steering of the fuel cell vehicle 10 and steers the wheel 14. Similarly, the power steering mechanism 60 receives a high-voltage power supply to the positive lead-in line 64 and the negative lead-in line 66 through the relay 62, and operates as a high-voltage component.

  The secondary battery 80 is an auxiliary battery formed using a lead storage battery or the like. In the secondary battery 80, a cell group 82 in which both electrodes are immersed in an electrolyte is connected in series to enable high-voltage power supply. A relay 84 provided in the circuit is a switch that controls power supply and charging execution and stopping by the secondary battery 80. A negative line 90 and a positive line 92 extend from the negative terminal 86 and the positive terminal 88 of the secondary battery 80, respectively. The negative line 90 and the positive line 92 are connected to the air conditioner 40 via the relay 48. Thereby, the air conditioner 40 can be operated even when the operation of the fuel cell 20 is stopped. Similarly, the electric power from the secondary battery 80 is supplied to the air compressor 50 and the power steering mechanism 60 via the relays 58 and 68, respectively.

  The leakage detector 100 is a device that detects a leakage generated in the high-voltage component group. That is, low voltage components such as indoor lighting and a speed meter supplied with power from an auxiliary power supply system (usually composed of a 12V battery and a DC / DC converter provided as necessary) provided separately in the fuel cell vehicle 10 Leakage is detected not for the group but for a group of components having a higher voltage than these. In the leakage detector 100, an intermediate potential is input from the terminal 30 of the fuel cell 20 and is connected to the resistor 102. The other end of the resistor 102 is connected to the voltage detection unit 106 in addition to being connected to the connection unit 105 of the vehicle body 12 via the resistor 104. The voltage detection unit 106 is a device that detects the voltage between the resistor 102 and the resistor 104, and thereby detects that a leakage current has flowed through the circuit connecting the resistor 102 and the resistor 104, and the current amount and the flow direction. be able to. When the voltage detector 106 detects a leakage, the information is output to the warning output unit 108. Then, the warning output unit 108 outputs warning information indicating that a leakage has been detected to the control unit 110.

  The control unit 110 is a device that controls the travel of the fuel cell vehicle 10 and mounted components. The control unit 110 performs control by hardware having a calculation function and software (program) that defines the operation thereof. The control unit 110 includes a component specifying unit 112 and a travel setting unit 114.

  When the component identification unit 112 receives a warning notification that the leakage has been detected from the leakage detector 100, the component identification unit 112 performs processing for identifying in which high-voltage component the leakage has occurred. Specifically, in the process, temporary disconnection and reconnection from the fuel cell 20 are sequentially performed on each high-voltage component. Then, it is confirmed whether or not the leakage warning from the leakage detector 100 is stopped while the high voltage component is disconnected. As a result, when the leakage is stopped, it is determined that the high voltage component is the cause of the leakage. In addition, the component identification unit 112 detects the leakage current in which part of the high-voltage component (positive side or negative side) based on the information on the polarity (flow direction) of the leakage current detected by the leakage detector 100. It can also be determined whether or not.

  The travel setting unit 114 determines whether or not the vehicle can travel without the high voltage component when the component identifying unit 112 identifies the high voltage component that has caused the leakage, and if so, sets the setting. To implement. That is, the travel setting unit 114 stores in advance a list of high-voltage components that can travel the vehicle without being used, and refers to the list to determine whether travel is possible. When the vehicle travels, control is performed so that the relay of the high-voltage component that has leaked is kept in a disconnected state. As a result, it becomes possible to run the vehicle while ensuring safety by isolating the high-voltage components that have leaked electricity. Generally, the processing in the travel setting unit 114 cannot be performed while the fuel cell vehicle 10 is traveling. Therefore, it is implemented as a mode different from the normal processing mode for running the vehicle.

  Here, a phenomenon in the case where a leakage occurs will be described. When there is no leakage, no leakage current flows through the leakage detector 100. The terminal 30 having an intermediate potential in the fuel cell 20 is grounded to the connection portion 105 of the vehicle body 12 via the resistors 102 and 104 in the leakage detector 100. Since the vehicle body 12 has a large electric capacity and is connected to the ground through the wheels 14, it can be said to be “grounded”. Insulation between the vehicle body 12 and the circuit of the high voltage component is ensured in a normal state. That is, the resistors 102 and 104 and the circuit of the high voltage component are in a partially disconnected state and do not form a circuit.

  However, when leakage occurs, a circuit including the resistors 102 and 104 and a circuit of a high voltage component is formed. For example, in the power steering mechanism 60 as a high-voltage component, it is assumed that water wettability occurs between the negative lead-in wire 66 and the vehicle body 12, and electric leakage occurs through the electric leakage unit 130. In this case, the negative lead-in wire 66 and the connection part 105 are electrically connected via the electric leakage part 130 and the current flow path 132 formed in the metallic vehicle body 12. Therefore, a large circuit including the resistors 102 and 104 of the leakage detector, the terminal 30 of the fuel cell 20, the negative stack 22 and the negative terminal 26, and the negative line 32 is formed. Then, a leakage current is caused to flow by the stack 22 that provides an electromotive force to the circuit.

  Next, processing performed in the battery car of FIG. 1 will be described with reference to FIG. FIG. 2 is a flowchart for explaining the detection flow and the subsequent processing flow of the control unit.

  When starting the fuel cell vehicle 10 or performing a leakage check, it is necessary to start the fuel cell 20 first. When the fuel cell 20 is activated, all the high-voltage component relays are normally connected for the reason that it is necessary for the activation (S10). In the example of FIG. 1, the relays 42, 52, and 62 of the air conditioner 40, the air compressor 50, and the power steering mechanism 60 are set to the connected state using the power of the secondary battery 80. Subsequently, after the fuel cell 20 is started (S12) and warmed up as necessary, sufficient power is supplied to the high voltage components.

  At this time, it is assumed that a leakage occurs. Then, the voltage detection unit 106 of the leakage detector 100 detects a leakage current, and the warning output unit 108 outputs a warning of leakage occurrence to the control unit 110 (S14).

  When the warning is notified, the control unit 110 performs a process of identifying a leakage point by the component identifying unit 112. In this process, each high-pressure component is temporarily separated sequentially. Therefore, first, the relay 42 is disconnected, and the air conditioner 40 is isolated from the circuit of the fuel cell 20 (S16). Then, it is checked whether or not leakage detector 100 continues to detect the leakage (S18). When the leakage is not detected, it is determined that the isolated air conditioner 40 is the cause of the leakage, and the information is recorded in a memory or the like in the control unit 110 (S20).

  Subsequently, the traveling setting unit 114 in the control unit 110 determines whether or not the air conditioner 40 is an indispensable device for traveling of the fuel cell vehicle 10 (S22). The air conditioner 40 is not required for traveling of the fuel cell vehicle 10 as long as the driver withstands the heat in the room, and is registered in the list stored in advance as unnecessary for traveling. Therefore, the air conditioner 40 is kept in an isolated state, and a warning is given to the driver that the air conditioner 40 cannot be used due to electric leakage (S24). In this way, the process for detecting electric leakage is completed (S26), and the process in the control unit 110 shifts to a mode for causing the fuel cell vehicle 10 to travel. In this mode, the fuel cell vehicle 10 can travel with the air conditioner 40 disconnected.

  When the air conditioner 40 is necessary for traveling, separate traveling is not allowed. Therefore, traveling of the vehicle is prohibited (S28), and the processing mode for detecting leakage is terminated (S30). Therefore, in this case, the fuel cell vehicle 10 cannot be run even when the processing of the control unit 110 is in the running mode. The driver is notified to that effect.

  If leakage is continuously detected in step S18, it is determined that the air conditioner 40 is not the cause of leakage. Therefore, the relay 42 is reconnected and the power supply to the air conditioner 40 is resumed (S32). Subsequently, a leakage check is performed on the air compressor 50 as the next high-voltage device. That is, the relay 52 for supplying power to the air compressor 50 is disconnected (S34), and in this case, it is determined whether or not the leakage is detected continuously (S36). And the process similar to the case of the air conditioner 40 is repeated.

  Thereafter, the same processing is repeated for each high voltage component. Then, for the high-voltage component in which the electric leakage is detected, a measure is taken to enable the traveling with the fuel cell vehicle 10 disconnected unless it is indispensable for the traveling of the fuel cell vehicle 10.

  Here, examples of high-voltage components of a fuel cell vehicle that are not indispensable for traveling are given. As such an example, first, there are high voltage components prepared in two systems. The two high-voltage components prepared are generally designed so that the fuel cell vehicle 10 can run even when one system cannot be used.

  An example of a high-voltage component that is prepared for only one system but is not indispensable for the traveling of the fuel cell vehicle is an air compressor that supplies compressed air to the fuel cell. When the air compressor is not used, the fuel cell output is reduced, but traveling is not impossible. The power steering mechanism that assists the rotation of the steering wheel, if not used, makes the steering operation heavy, but does not hinder the wheel steering. Also, a water pump or a fan for cooling the fuel cell may not be used as long as the fuel cell is not excessively heated. Furthermore, a radiator used for consumption of regenerative power from the motor is not indispensable for traveling.

It is the schematic which shows the structure of the fuel cell vehicle concerning this Embodiment. It is a flowchart explaining the flow of the process concerning a leak detection.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Fuel cell vehicle, 12 Car body, 14 Wheel, 20 Fuel cell, 22, 24 Stack, 26 Negative terminal, 28 Positive terminal, 30 Terminal, 32 Negative track, 34 Positive track, 40 Air conditioner, 42, 48, 52, 58 , 62, 68, 84 Relay, 44, 54, 64 Positive lead-in wire, 46, 56, 66 Negative lead-in wire, 50 Air compressor, 60 Power steering mechanism, 80 Secondary battery, 82 Cell group, 86 Negative electrode terminal, 88 Positive electrode terminal, 90 Negative line, 92 Positive line, 100 Earth leakage detector, 102, 104 Resistance, 105 Connection part, 106 Voltage detection part, 108 Warning output part, 110 Control part, 112 Component identification part, 114 Travel setting part, 130 Earth leakage part, 132 Flow path.

Claims (6)

A fuel cell for generating electric power;
A plurality of electrical components to which power generated by the fuel cell is supplied;
A leakage detector that detects that a leakage has occurred in any of the plurality of electrical components based on a leakage current associated with the leakage; and
When the leakage detector detects a leakage, the leakage detector is used to identify in which part of the plurality of electrical components the leakage has occurred,
A fuel cell system comprising: The fuel cell system according to claim 1, wherein
A separation means for separating a part of the plurality of electrical components from the power supply line;
The specifying means specifies in which part of the plurality of electrical components the electric leakage has occurred based on whether or not the electric leakage detector detects the electric leakage when the disconnecting means performs the disconnection. A fuel cell system. The fuel cell system according to claim 2, wherein
The disconnecting means has a function of disconnecting each electrical component from the power supply line,
The specifying means specifies in which electrical component the electric leakage has occurred, based on whether or not the electric leakage detector detects electric leakage when disconnecting by the disconnecting means. system. The fuel cell system according to any one of claims 1 to 3,
A fuel cell has its intermediate potential connected to ground through a resistor,
The leakage detector is configured to detect that leakage has occurred between any of the plurality of electrical components and the ground based on the leakage current flowing through the resistor. The fuel cell system according to claim 1, wherein
A fuel cell has its intermediate potential connected to ground through a resistor,
The leakage detector detects that a leakage has occurred between one of the plurality of electrical components and the ground based on the leakage current that flows through the resistor.
The fuel cell system characterized in that the specifying means specifies in which part of the plurality of electrical components the electrical leakage has occurred based on the polarity of the electrical leakage current. A fuel cell system according to any one of claims 1 to 5,
A vehicle equipped with this fuel cell system;
A drive mechanism for driving the vehicle using the electric power generated by the fuel cell;
Means for causing the vehicle to travel in a state where the electrical component is electrically disconnected when the electrical component identified as the leakage portion by the identifying means is not essential for traveling of the vehicle;
A fuel cell vehicle comprising:

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