JP2005094914A - Power supply system of fuel cell vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid beforehand problems of the increase of the power consumption of a battery caused by the decrease of a power generation amount of a fuel cell, and deteriorations of the battery and a battery electric path opening/closing switch or the like by effectively preventing that a request of excessive power is instantaneously sent to the battery, when the power generation amount of the fuel cell is decreased. <P>SOLUTION: When the decrease of the power generation amount of the fuel cell 1 is detected, a battery discharge current value supplied from the battery 21 when covering all the amount of the deterioration of the power generation of the fuel cell 1 with power from the battery 21 is estimated, an allowable current value allowable by the battery 21 and a battery main relay 27 is estimated, and when the battery discharge current value exceeds the battery allowable current value, the battery main relay 27 is switched to an off-state, thus disconnecting a battery load electric path. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power supply system for a fuel cell vehicle equipped with a fuel cell as a main power source and a battery as an auxiliary power source.

  Fuel cell technology that enables clean exhaust and high energy efficiency is attracting attention as a countermeasure against environmental problems in recent years, especially air pollution caused by automobile exhaust gas and global warming due to carbon dioxide, Research and development on a fuel cell vehicle equipped with such a fuel cell as a main power source has been actively conducted.

  Although fuel cells can achieve high energy efficiency, they are not sufficiently responsive to required power fluctuations. Therefore, fuel cell vehicles are usually equipped with batteries as auxiliary power supplies in addition to fuel cells. The response delay of the fuel cell is compensated by the electric power from the battery. In such a fuel cell vehicle, even if the power generation amount of the fuel cell suddenly decreases due to a failure of the fuel cell or the like, the power generation amount of the fuel cell is reduced by the power from the battery as an auxiliary power source. In addition, a certain amount of traveling is possible. However, since there is a limit to the power that can be supplied from the battery, in an emergency such as when a fuel cell failure occurs, the power from the battery should be used efficiently to ensure the mileage of the fuel cell vehicle. Is important.

From such a viewpoint, when an abnormal output drop of the fuel cell is detected, a technique for efficiently using the power from the battery to secure the travel distance by suppressing unnecessary battery power consumption is proposed. (For example, refer to Patent Document 1). In the technique disclosed in Patent Document 1, when an abnormal output drop of the fuel cell is detected, the power supply from the battery to the auxiliary machine is suppressed, or the maximum value of the current extracted from the battery is limited. Furthermore, by setting the rotation speed and torque of the drive motor in accordance with the remaining amount of power that can be output by the battery, the power from the battery is used efficiently.
JP 2003-153461 A

  By the way, various controls when the output of the fuel cell is abnormally reduced as described above are carried out after the control unit detects a decrease in the output of the fuel cell and performs various arithmetic processes to determine specific control contents, and based on that, actual control is performed. Therefore, there is a delay corresponding to the calculation period of the control unit between the time when the output of the fuel cell is reduced and the time when the actual control is executed. However, in the above-described prior art, since such a delay is not taken into consideration, when the fuel cell causes an abnormal decrease in output, the battery instantaneously requests all the power required by the vehicle, There was a problem of increasing power consumption.

  Furthermore, if the total power required by the vehicle is high, there is a possibility of instantaneously requesting a current exceeding the allowable current value of the battery and the battery electric path opening / closing switch, which deteriorates the battery and the battery electric path opening / closing switch. There was a problem of becoming a factor.

  The present invention was devised to solve the above-described problems of the prior art, and when the power generation amount of the fuel cell decreases, the battery instantaneously requires excessive power. It is possible to provide a power supply system for a fuel cell vehicle that can effectively prevent this and avoid problems such as an increase in power consumption of the battery and deterioration of the battery and battery electric path opening / closing switch due to this. It is aimed.

  In the power supply system of the present invention, the system control device that controls the operation of the power supply system includes vehicle required power calculation means, vehicle required power limiting means, and battery electric path opening / closing switch on / off switching means. The vehicle required power calculating means calculates the total power required by the vehicle and requests the vehicle required power from the fuel cell or battery. The vehicle required power limiting means is configured such that the vehicle required power calculating means The vehicle power requirement required for the battery is limited. The battery electrical path opening / closing switch on / off switching means switches on / off of the battery electrical path opening / closing switch provided in the battery / load electrical path that connects the battery as the auxiliary power source and the load. When the system control device determines that the power supplied from the fuel cell as the main power source has decreased by a predetermined amount or more, the system control device limits the vehicle power requirement by an amount corresponding to the amount of power supplied from the fuel cell. The battery electric path open / close switch is switched to the OFF state to cut off the battery / load electric path.

  Here, when the power supplied from the fuel cell is reduced by a predetermined amount or more, for example, it is assumed that the power generation amount of the fuel cell is reduced and that the power generation amount of the fuel cell is compensated for by the power from the battery. In this case, the current value to be supplied from the battery exceeds the allowable current value for the battery and the battery electrical path open / close switch. Also, for example, when the fuel cell electrical circuit open / close switch provided in the fuel cell / load electrical circuit connecting the fuel cell and the load is turned off, or the power generated by the fuel cell is converted into a direct current. When the output DC voltage converter is turned off, and when it is assumed that all the power required by the vehicle is covered by the power from the battery, the current value to be supplied from the battery is A case where the battery electric path opening / closing switch exceeds an allowable current value may be determined as a case where the power supplied from the fuel cell has decreased by a predetermined amount or more.

  In the power supply system of the present invention as described above, when the power supplied from the fuel cell decreases by a predetermined amount or more and the battery instantaneously requires excessive power, the battery electrical path The open / close switch is switched to the OFF state, and the battery / load electric path is interrupted.

  According to the power supply system of the present invention, when the battery instantaneously requires excessive power, the battery electrical path open / close switch is switched to the off state, and the battery / load electrical path Therefore, problems such as an increase in power consumption of the battery and deterioration of the battery and the battery electric path open / close switch, which are problems when excessive power is instantaneously taken out from the battery, can be avoided.

  Hereinafter, specific embodiments of a power supply system to which the present invention is applied will be described in detail with reference to the drawings. This power supply system is a power supply system for a fuel cell vehicle equipped with a fuel cell as a main power source and a battery as an auxiliary power source, and particularly when the power supplied from the fuel cell as the main power source suddenly decreases, It has a great feature in that it effectively prevents instantaneously taking out excessive electric power from a battery as an auxiliary power source, and problems caused by this can be avoided in advance.

(First embodiment)
First, a specific example of a fuel cell mounted as a main power source in a fuel cell vehicle and a fuel cell power generation system using the fuel cell will be described with reference to FIG.

  The fuel cell power generation system includes a fuel cell 1, a fuel supply system that supplies hydrogen (or hydrogen-rich gas) as a fuel to the fuel cell 1, and an air supply system that supplies an oxidant (air). 1 is configured to supply power obtained by power generation 1 to the drive unit 2 of the fuel cell vehicle.

  The fuel cell 1 has a structure in which power generation cells in which a fuel electrode to which hydrogen is supplied and an air electrode to which oxygen (air) is supplied are stacked with an electrolyte / electrode catalyst composite interposed therebetween are stacked in multiple stages. It converts chemical energy into electrical energy by a chemical reaction. At the fuel electrode of each power generation cell, hydrogen ions and electrons are dissociated when hydrogen is supplied, hydrogen ions pass through the electrolyte, electrons generate power through an external circuit, and move to the air electrode side. To do. In the air electrode, oxygen in the supplied air reacts with the hydrogen ions and electrons to generate water, which is discharged to the outside.

  As the electrolyte of the fuel cell 1, for example, a solid polymer electrolyte is used in consideration of high energy density, low cost, light weight, and the like. The solid polymer electrolyte is made of an ion (proton) conductive polymer film such as a fluororesin ion exchange membrane, and functions as an ion conductive electrolyte when saturated with water.

  The fuel cell 1 is connected to a cell voltage detection device 3 that detects the voltage of each power generation cell or power generation cell group, and the output of the cell voltage detection device 3 is taken into the system controller 100. Yes. The system controller 100 controls the operation of the entire power supply system to which the present invention is applied based on built-in control software.

  The fuel supply system includes a high-pressure hydrogen tank 4, a variable valve 5, an ejector 6, a hydrogen supply pipe 7, and a hydrogen circulation pipe 8. Then, the hydrogen gas supplied from the high-pressure hydrogen tank 4 that is a hydrogen supply source is sent to the hydrogen supply pipe 7 through the variable valve 5 and the ejector 6, and is humidified in the humidifier 9. Supplied to the fuel electrode. The humidifier 9 is provided with a humidifying pure water path 10 and a pure water pump 11, and the humidification amount of hydrogen gas is controlled by the flow rate, temperature, etc. of the pure water.

  In the fuel cell 1, not all of the supplied hydrogen gas is consumed, and the remaining hydrogen gas (hydrogen gas discharged from the fuel cell 1) is circulated by the ejector 6 through the hydrogen circulation pipe 8 and newly added. It is mixed with the supplied hydrogen gas and supplied again to the fuel electrode of the fuel cell 1. A purge valve 12 and a purge pipe 13 are provided on the outlet side of the fuel cell 1. Impurities, nitrogen, and the like are accumulated by circulating hydrogen in the hydrogen circulation pipe 8, which may reduce the hydrogen partial pressure and reduce the efficiency of the fuel cell 1. Therefore, by providing a purge valve 12 and a purge pipe 13 on the outlet side of the fuel cell 1, impurities, nitrogen, and the like can be removed from the hydrogen circulation pipe 8.

  In the fuel supply system, a hydrogen pressure sensor 14 and a hydrogen flow sensor 15 are provided in the middle of the hydrogen supply pipe 7, and the pressure and flow rate of hydrogen supplied to the fuel electrode of the fuel cell 1 are determined by these sensors. Can be detected.

  The air supply system is composed of a compressor 16 for sending air, an air supply pipe 17, and a throttle 18. The air as the oxidant supplied by the compressor 16 is supplied to the air electrode of the fuel cell 1 from the air supply pipe 17 through the humidifier 9 like the hydrogen gas. Oxygen not consumed in the fuel cell 1 and other components in the air are discharged from the fuel cell 1 through the throttle 18.

  Also in this air supply system, an air pressure sensor 19 and an air flow rate sensor 20 are provided in the middle of the air supply pipe 17 so that the pressure and flow rate of air supplied to the fuel cell 1 can be detected by these sensors. It has become.

  In the fuel cell power generation system configured as described above, the air pressure sensor 19 that detects the air pressure at the inlet of the fuel cell 1, the air flow sensor 20 that detects the air flow rate, the hydrogen pressure sensor 14 that detects the hydrogen pressure, The system controller 100 monitors the outputs from the hydrogen flow sensor 15 that detects the hydrogen flow rate and the cell voltage detection device 3. The system controller 100 controls the compressor 16, the throttle 18, the variable valve 5 and the like so that each detection value read from each of these detection means becomes a predetermined target value determined from the target power generation amount at that time. At the same time, an output (current value) to be taken out from the fuel cell 1 to the drive unit 2 is commanded according to the pressure and flow rate actually realized with respect to the target value.

  Next, the overall configuration of the power supply system of the fuel cell vehicle to which the present invention is applied will be described with reference to FIG.

  This power supply system controls power extraction from the fuel cell 1 as the main power source and power extraction from the battery 21 as the auxiliary power source, while the power extracted from the fuel cell 1 and the battery 21 is supplied to the drive motor 22 and others. To the auxiliary machine 23 and the like. A part of this power supply system is unitized as the drive unit 2 described above. The drive unit 2 is connected to the controller 100, the fuel cell 1 as the main power source, the battery 21 as the auxiliary power source, the drive motor 22 and other auxiliary machines 23.

  The drive unit 2 is provided with a fuel cell main relay (fuel cell electric path open / close switch) 24, a DC voltage converter 25, a drive motor inverter 26, a battery main relay (battery electric path open / close switch) 27, and a battery controller 28. Yes.

  The fuel cell main relay 24 is provided in a fuel cell / load electric path that connects the fuel cell 1 and a load such as the drive motor 22, and can be switched on / off under the control of the system controller 100. . When the fuel cell main relay 24 is turned on, the fuel cell / load electric path is turned on, and when the fuel cell main relay 24 is turned off, the fuel cell / load electric path is cut off.

  The DC voltage converter 25 converts the electric power generated by the fuel cell 1 into a DC current and outputs it. A current sensor 29 that detects an input current of the DC voltage conversion device 25 and a voltage sensor 30 that detects an input voltage are connected to the front stage (the fuel cell 1 side) of the DC voltage conversion device 25. Further, a current sensor 31 for detecting an output current of the DC voltage conversion device 25 and a voltage sensor 32 for detecting an output voltage are connected to the subsequent stage (on the drive motor 22 side) of the DC voltage conversion device 25.

  The drive motor inverter 26 adjusts the power supplied to the drive motor 22 in accordance with a command from the system controller 100 and controls the rotation speed and torque of the drive motor 26 to have desired values.

  The battery main relay 27 is provided in a battery / load electric path that connects the battery 21 and a load such as the drive motor 22, and is switched on / off under the control of the system controller 100. When the battery main relay 27 is turned on, the battery / load electric path is turned on. When the battery main relay 27 is turned off, the battery / load electric path is cut off.

  The battery controller 28 monitors the state of the battery 21 and supplies the information to the system controller 100, and controls the extraction of power from the battery 21 in accordance with a command from the system controller 100. A current sensor 33 that detects the output current of the battery 21 and a voltage sensor 34 that detects the output voltage are connected between the battery controller 28 and the battery 21.

  In the power supply system configured as described above, the system controller 100 includes the detection signals from the current sensors 29, 31, 33 and the voltage sensors 30, 32, 34, the DC voltage converter 25, the drive motor inverter 22, the battery. Information from the controller 28 is taken in as appropriate, and the operation of the entire power supply system is controlled based on the built-in control software. In particular, in the power supply system to which the present invention is applied, when the system controller 100 detects a sudden drop in the power supplied from the fuel cell 1, the battery main relay 27 is switched to the off state to By effectively blocking the electric path and taking out excessive electric power instantaneously from the battery 21, problems such as an increase in power consumption of the battery 21 and deterioration of the battery 21 and the battery main relay 27 are obviated. I try to avoid it.

  Here, the details of the control by the system controller 100 as described above will be specifically described. The system controller 100 executes the built-in control software, for example, as shown in the functional block diagram of FIG. 3, the vehicle required power calculating means 101, the fuel cell power generation amount decrease detecting means 102, and the vehicle required power limiting means 103. Each function of the battery supply current value estimating means 104, the battery allowable current estimating means 105, and the battery main relay on / off switching means 106 is realized.

  The vehicle required power calculation means 101 calculates the total power (vehicle required power) required for driving the drive motor 22 and other auxiliary machines 23, and requests this vehicle required power from the fuel cell 1 and the battery 21. Is.

  The fuel cell power generation amount decrease detecting means 102 detects a decrease in the power generation amount of the fuel cell 1, and specifically, the input current value of the DC voltage converter 25 detected by the current sensor 29 and the voltage sensor 30 and The power generation amount of the fuel cell 1 at that time is obtained from the input voltage value, and the value is compared with the value obtained one calculation cycle before, thereby detecting the power generation amount decrease of the fuel cell 1.

  The vehicle required power limiting means 103 is a vehicle required power requested by the vehicle required power calculation means 101 to the fuel cell 1 or the battery 21 when the fuel cell power generation amount decrease detecting means 102 detects a decrease in the power generation amount of the fuel cell 1. Is limited by an amount corresponding to the power generation reduction amount of the fuel cell 1.

  It is assumed that the battery supply current value estimation unit 104 compensates all the power generation decrease amount of the fuel cell 1 with the power from the battery 21 when the fuel cell power generation amount decrease detection unit 102 detects the power generation amount decrease of the fuel cell 1. In this case, the current value to be supplied from the battery 21 is estimated.

The battery allowable current value estimation means 105 estimates a current value that can be tolerated by the battery 21 and the battery main relay 27. Specifically, the battery allowable current value estimation unit 105, for example, based on the blown fuse characteristic of the battery main relay 27 as shown in FIG. 4 was continued energization of the between the battery main relay 27 for a predetermined time T ₁ Even in this case, the maximum current value that does not cause the fuse to blow is estimated as a current value C _{1mt that} can be allowed by the battery 21 and the battery main relay 27. Here, the predetermined time T ₁ is, for example, a time substantially equal to one calculation cycle of the system controller 100.

The battery main relay on / off switching means 106 switches on / off of the battery main relay 27. In particular, the current value estimated by the battery supply power estimation means 104 is estimated by the battery allowable current value estimation means 105. The battery main relay on / off switching means 106 switches the battery main relay 27 to the off state to control the battery / load electric path to be cut off when the current value C _lmt is exceeded.

  When the power generation amount of the fuel cell 1 rapidly decreases, the power generation amount decrease of the fuel cell 1 is detected by the fuel cell power generation amount decrease detecting unit 102, and the vehicle power demand limiting unit 103 determines the amount corresponding to the power generation decrease amount. Only the vehicle power requirement will be limited. Since the restriction of the required vehicle power is realized by the arithmetic processing of the system controller 100, as shown in FIG. 5 (a), the required vehicle power is actually restricted after a decrease in the power generation amount of the fuel cell 1 is detected. There will be a slight delay in the process. As a result, as shown in FIG. 5B, the current value (battery discharge current value) supplied from the battery 21 peaks at the point when the restriction on the vehicle required power is actually started, and the fuel cell 1 is the maximum. It will increase by the amount corresponding to the amount of power generation decrease. When the increased battery discharge current value exceeds the current value allowable for the battery 21 or the battery main relay 27, the battery 21 or the battery main relay 27 is deteriorated, specifically, for example, the battery main relay 27. This may cause the fuse to melt.

Therefore, in the power supply system of the present embodiment, when the fuel cell power generation amount decrease detection unit 102 detects the power generation amount decrease of the fuel cell 1, the battery supply current value estimation unit 104 causes the fuel cell 1 power generation decrease amount to decrease. Is estimated by the electric power from the battery 21, and the current value to be supplied from the battery 21 is estimated, and the battery allowable current value estimation means 105 is an allowable current value for the battery 21 and the battery main relay 27. C _lmt is estimated, and when the current value estimated by the battery supply current value estimation unit 104 exceeds the current value C _lmt estimated by the battery allowable current value estimation unit 105, the battery 21 and the battery main relay 27 are deteriorated. Battery main relay on / off switching means 106 is connected to the battery main. Switching the laser 27 off state, so as to cut off the battery load electrical path. The battery 21 and the battery main relay 27 are protected so that excessive current cannot be taken out from the battery 21.

  Next, a flow of a series of processes performed by the system controller 100 as described above will be specifically described with reference to a flowchart of FIG. The control flow shown in FIG. 6 is executed by the system controller 100 every predetermined time (for example, 10 msec) from the start of operation of the fuel cell system.

First, in step S1, the vehicle required power calculation means 101 calculates the total power required by the vehicle by calculation. Specifically, the vehicle required power calculation means 101, for example, when the power required by the drive motor 22 is P _MTR [kW] and the power required by the other auxiliary machine 23 is P _AUX [kW] The total power P _ALL [kW] required by the vehicle is obtained by Expression (1).

P _ALL = P _MTR + P _AUX (1)
Next, in step S2, the fuel cell power generation amount decrease detecting means 102 detects the power generation amount decrease of the fuel cell 1 and the power generation decrease amount at that time. Specifically, the input current value of the DC voltage converter 25 detected by the current sensor 29 is C _{PM_in} [A], and the input voltage value of the DC voltage converter 25 detected by the voltage sensor 30 is V _{PM_in} [V]. Then, the power generation amount P _GRS [kW] of the fuel cell 1 is obtained by the following equation (2).

P _GRS = C _{PM_in} × V _{PM_in} (2)
Here, assuming that the power generation amount of the fuel cell 1 obtained before one calculation cycle by the system controller 100 is P _GRS z [kW], the power generation decrease amount ΔP _GRS [kW] of the fuel cell 1 is calculated by the following equation (3). can do. A case where ΔP _GRS > 0 in the following formula (3) is a case where the power generation amount of the fuel cell 1 is reduced.

ΔP _GRS = P _GRS −P _GRS z (3)
Next, in step S <b> 3, the vehicle required power is limited by an amount corresponding to the power generation reduction amount by the vehicle required power limiting means 103. Specifically, the vehicle required power limiting means 103 includes the total power P _ALL [kW] required by the vehicle obtained in step S1, and the power generation reduction amount ΔP _GRS [kW] of the fuel cell 1 detected in step S2. Thus, the vehicle required power limit value P _{ALL_limit} [kW] is determined by the following equation (4).

P _{ALL_limit} = P _ALL −ΔP _GRS (4)
Next, in step S4, the battery supply current value estimation means 104 supplies from the battery 21 when it is assumed that the power generation reduction amount of the fuel cell 1 detected in step S2 is all supplemented with the power from the battery 21. Is estimated. Specifically, if the output voltage value of the battery 21 detected by the voltage sensor 34 is V _VATT [V], the current value C _{BATT_GRS} from the battery 21 corresponding to the power generation decrease amount ΔP _GRS of the fuel cell 1 is Is obtained by the following equation (5).

C _{BATT_GRS} = ΔP _GRS / V _VATT (5)
If the output current value of the battery 21 detected by the current sensor 33 at that time is C _VATT [A], the total current value C _{BATT_ALL} to be supplied from the battery 21 is obtained by the following equation (6). .

C _{BATT_ALL} = C _VATT + C _{BATT_GRS} (6)
Next, in step S5, the battery allowable current value estimation unit 105 allows the battery 21 and the battery main relay 27 to accept an allowable current value based on, for example, the fuse blowing characteristics of the battery main relay 27 as shown in FIG. C _lmt is estimated.

Next, in step S6, the current value C _{BATT_ALL} estimated by the battery supply current value estimation unit 104 in step S4 is compared with the current value C _lmt estimated by the battery allowable current value estimation unit 105 in step S5, and the battery supply is performed. If the current value _{C BATT_ALL} the current value estimation unit 104 estimates exceeds the current value _{C lmt} battery allowable current value estimation unit 105 is estimated, at step S7, the battery main relay by the battery main relay on and off switching means 106 27 is switched to the OFF state, and the battery / load electric path is interrupted. Thereby, the extraction of electric power from the battery 21 is forcibly stopped, and the battery 21 and the battery main relay 27 are protected.

On the other hand, if it is determined in step S6 that the current value C _{BATT_ALL} estimated by the battery supply current value estimation unit 104 is _{equal to} or less than the current value C _lmt estimated by the battery allowable current value estimation unit 105, the battery main relay 27 Is terminated without being switched to the off state. That is, in this case, the current value C _{BATT_ALL} estimated by the battery supply current value estimation unit 104 is not so large and there is no _fear of causing deterioration of the battery 21 or the battery main relay 27, so that the extraction of power from the battery 21 is continued. Thus, the amount of power generation reduction of the fuel cell 1 is covered by this battery 21.

  As described above, in the power supply system of the present embodiment, the amount of power generated by the fuel cell 1 suddenly decreases, and the battery 21 is instantaneously requested to have excessive power. In some cases, the battery main relay 27 is switched to the OFF state by the control of the system controller 100 so as to cut off the battery / load electric path, which causes a problem when excessive power is instantaneously extracted from the battery 21. Problems such as an increase in power consumption of the battery 21 and deterioration of the battery 21 and the battery main relay 27 can be avoided in advance.

In the example described above, when the battery allowable current value estimation unit 105 of the system controller 100 estimates the allowable current value of the battery 21 and the battery main relay 27 based on the fuse blowing characteristics of the battery main relay 27. the system substantially equal time as one operation cycle of the controller 100 as a predetermined time T _1, the maximum current value that does not lead to blown fuse even when allowed to continue energization of the between the battery main relay 27 for the predetermined time T _{1 Is} estimated as a current value C _1mt that the battery 21 and the battery main relay 27 can tolerate.

  This considers the protection of the battery 21 and the battery main relay 27 as the highest priority, and forcibly takes out the electric power from the battery 21 when there is a slight possibility that the battery 21 and the battery main relay 27 will be deteriorated. The battery 21 and the battery main relay 27 are surely protected by being stopped, but the current value (battery discharge current value) supplied from the battery 21 when the power generation amount from the fuel cell 1 is reduced is as follows: As shown in FIG. 5 (b), the transition is made in a mountain shape with a peak when the restriction of the required vehicle power starts as time passes, so that the battery 21 and the battery main relay 27 are actually deteriorated. The time when the excessive current is taken out from the battery 21 is considered to be a short time near the peak.

  Here, when estimating the allowable current value of the battery 21 and the battery main relay 27 based on the fuse blowing characteristics of the battery main relay 27, as shown in FIG. As the time is assumed to be shorter, the allowable current value can be set to a higher value. When the allowable current value of the battery 21 and the battery main relay 27 is set to a high value, the battery main relay 27 is actually used even in a situation where there is a low possibility that the battery 21 or the battery main relay 27 will be deteriorated. It is possible to effectively avoid the inconvenience of switching to the off state and forcibly stopping the extraction of power from the battery 21.

From this point of view, when the battery allowable current value estimating means 105 estimates the allowable current value, the energization continuation time to the battery main relay 27 is set to a minute time ΔT ₁ shorter than one calculation cycle of the system controller 100. When the energization to the battery main relay 27 is continued during the minute time ΔT _1, the maximum current value that does not cause the fuse to blow is estimated as an allowable current value for the battery 21 and the battery main relay 27. It is also effective. Note that the value of the minute time ΔT ₁ may be set to an optimum value in advance in consideration of the trend of the battery discharge current and the like.

In performing such control, the system controller 100 executes the control flow shown in FIG. 8 instead of the control flow shown in FIG. In the control flow shown in FIG. 8, the processing from step S11 to step S14 is the same as the processing from step S1 to step S4 of the control flow shown in FIG. In step S15, the battery allowable current value estimation means 105 determines the duration of energization to the battery main relay 27 from one calculation cycle of the system controller 100, based on the fuse blowing characteristics of the battery main relay 27 shown in FIG. a short minute time also [Delta] T _1, the maximum current value that no lead to blown fuse even when allowed to continue energization of the between the battery main relay 27 in the minute time [Delta] T _1, the battery 21 and the battery main relay 27 is allowed It is estimated as a possible current value C _{max — lmt} .

In step S16, the current value C _{BATT_ALL} estimated by the battery supply current value estimation unit 104 in step S14 is compared with the current value C _{max_lmt} estimated by the battery allowable current value estimation unit 105 in step S15, and the battery supply current is compared. If the current value _{C BATT_ALL} value estimating unit 104 has estimated exceeds the current value _{C Max_lmt} battery allowable current value estimation unit 105 has estimated, in step S17, the battery main relay on and off switching means 106 of the battery main relay 27 Switch to the off state to shut off the battery / load electrical path. On the other hand, when the current value C _{BATT_ALL} estimated by the battery supply current value estimation unit 104 is _{equal to} or less than the current value C _{max_lmt} estimated by the battery allowable current value estimation unit 105, the process is performed without switching the battery main relay 27 to the off state. Ends.

  As a result, when there is a low possibility of causing deterioration of the battery 21 or the battery main relay 27, when the possibility of causing deterioration of the battery 21 or the battery main relay 27 is high while continuing to take out power from the battery 21, The extraction of power from the battery 21 can be forcibly stopped to protect the battery 21 and the battery main relay 27.

(Second Embodiment)
Next, a second embodiment of the power supply system to which the present invention is applied will be described. In this embodiment, the basic configuration is the same as that of the first embodiment described above, and the contents of control by the system controller 100 are slightly different from those of the first embodiment. That is, in the first embodiment described above, an excessively large amount of power is instantaneously generated from the battery 21 due to a sudden decrease in the amount of power generation (such as a sudden decrease in cell voltage) in the fuel cell 1 during normal operation. The system controller 100 determines such a situation and protects the battery 21 and the battery main relay 27. However, in the present embodiment, the fuel cell 1 A fuel cell main relay 24 provided in a fuel cell / load electric path for connecting the motor and a load such as the drive motor 22, and a DC voltage conversion device 25 that converts the electric power generated by the fuel cell 1 into a DC current and outputs it. The power supply from the fuel cell 1 is cut off because of the self-protection due to the abnormality detection, so that excessive power is instantaneously taken out from the battery 21 due to this. On the assumption that the case where put away, is obtained as the protection of the battery 21 and the battery main relay 27 is achieved even when such a situation.

  Hereinafter, the contents of control by the system controller 100 characteristic of the present embodiment will be specifically described. The basic configuration of the entire power supply system is the same as that of the first embodiment described above (see FIG. 2), and therefore the description of the details of each part constituting the power supply system is omitted here.

  The system controller 100 in the power supply system of the present embodiment executes the built-in control software, for example, as shown in the functional block diagram of FIG. 9, the vehicle required power calculation means 111, the fuel cell main relay / DC voltage The functions of the converter off-state detecting unit 112, the vehicle required power limiting unit 113, the battery supply current value estimating unit 114, the battery allowable current estimating unit 115, and the battery main relay on / off switching unit 116 are realized.

  The vehicle required power calculation means 111 is required for driving the drive motor 22 and other auxiliary machines 23 in the same manner as the vehicle required power calculation means 101 realized by the system controller 100 of the first embodiment described above. Total power (vehicle required power) is calculated, and this vehicle required power is requested to the fuel cell 1 and the battery 21.

  The fuel cell main relay / DC voltage converter off state detecting means 112 detects that the fuel cell main relay 24 and the DC voltage converter 25 are turned off. Specifically, for example, a voltage sensor The output voltage value of the DC voltage conversion device 25 detected by 32, the input current value of the DC voltage conversion device 25 detected by the current sensor 29, the output current value of the DC voltage conversion device 25 detected by the current sensor 31, etc. Based on the above, it is determined whether or not the fuel cell main relay 24 and the DC voltage converter 25 are turned off.

  The vehicle required power limiting unit 113 limits the vehicle required power in the same manner as the vehicle required power limiting unit 103 realized by the system controller 100 of the first embodiment described above. The vehicle power requirement limiting means 113 realized by the system controller 100 is that the fuel cell main relay 24 or the DC voltage converter 25 is turned off by the fuel cell main relay / DC voltage converter OFF state detector 112. Is detected, the vehicle required power is limited so as to be within the range of power that the battery 21 can supply.

  The battery supply current value estimating means 114 assumes that the vehicle required power calculated by the vehicle required power calculating means 111 is all covered by the power from the battery 21, and in that case the current value to be supplied from the battery 21 is calculated. presume.

Similar to the battery allowable current value estimating means 105 realized by the system controller 100 of the first embodiment described above, the battery allowable current value estimating means 115 determines the current values that the battery 21 and the battery main relay 27 can allow. For example, based on the fuse blowing characteristics of the battery main relay 27 as shown in FIG. 4, for example, the battery main relay 27 is energized for a predetermined time T _{1 that} is substantially equal to one calculation cycle of the system controller 100. The maximum current value that does not cause the fuse to blow even if it is continued is estimated as the current value C _lmt that the battery 21 and the battery main relay 27 can tolerate.

The battery main relay on / off switching means 116 switches the battery main relay 27 on / off in the same manner as the battery main relay on / off switching means 106 realized by the system controller 100 of the first embodiment described above. In particular, when the current value estimated by the battery supply power estimation means 114 exceeds the current value C _lmt estimated by the battery allowable current value estimation means 115, the battery main relay on / off switching means 116. Switches the battery main relay 27 to the OFF state, and performs control to cut off the battery / load electric path.

  When the fuel cell main relay 24 and the DC voltage converter 25 are turned off for self-protection due to abnormality detection and the power supply from the fuel cell 1 is cut off, the state is the fuel cell main relay / DC voltage converter. The vehicle power requirement is detected by the off-state detection unit 112, and the vehicle power requirement limit unit 113 limits the vehicle power requirement so that the battery 21 can be supplied. At this time, since a slight delay occurs until the vehicle required power is actually limited, the current value (battery discharge current value) supplied from the battery 21 increases instantaneously. When the increased battery discharge current value exceeds the current value allowable for the battery 21 or the battery main relay 27, the battery 21 or the battery main relay 27 is deteriorated, specifically, for example, the battery main relay 27. This may cause the fuse to melt.

Therefore, in the power supply system of the present embodiment, the battery supply current value estimation unit 114 estimates the current value that will be supplied from the battery 21 when the vehicle required power is all covered by the power from the battery 21. The battery allowable current value estimating means 115 estimates the current value C _lmt that can be allowed by the battery 21 and the battery main relay 27, and the current value estimated by the battery supply current value estimating means 114 is the battery allowable current value estimating means 115. If the current value C _lmt estimated by the above is exceeded, it is determined that the battery 21 or the battery main relay 27 may be deteriorated, and the battery main relay on / off switching means 116 turns the battery main relay 27 off. To switch off the battery / load electric path. The battery 21 and the battery main relay 27 are protected so that excessive current cannot be taken out from the battery 21.

  Next, a flow of a series of processes performed by the system controller 100 as described above will be specifically described with reference to a flowchart of FIG. The control flow shown in FIG. 10 is executed by the system controller 100 every predetermined time (for example, 10 msec) from the start of operation of the fuel cell system.

First, in step S21, the total power P _ALL required by the vehicle is calculated by the vehicle required power calculation means 111 by calculation. The calculation method by the vehicle required power calculation unit 111 is the same as that in the first embodiment described above.

Next, in step S <b> 22, the battery supply current value estimation unit 114 supplies the vehicle required power P _ALL calculated by the vehicle required power calculation unit 111 with the power from the battery 21. The current value will be estimated. Specifically, assuming that the output voltage value of the battery 21 detected by the voltage sensor 34 is V _VATT [V], the current value C from the battery 21 when the vehicle required power P _ALL is entirely covered by the power from the battery 21. _{BATT_ALL} is obtained by the following equation (7).

C _{BATT_ALL} = P _ALL / V _VATT (7)
Next, in step S23, the battery allowable current value estimation means 115 allows the battery 21 and the battery main relay 27 to accept an allowable current value based on, for example, the fuse blowing characteristics of the battery main relay 27 as shown in FIG. C _lmt is estimated.

Next, in step S24, the current value C _{BATT_ALL} estimated by the battery supply current value estimation unit 114 in step S22 is compared with the current value C _lmt estimated by the battery allowable current value estimation unit 115 in step S23, and the battery supply is performed. If the current value C _{BATT_ALL} estimated by the current value estimation unit 114 is equal to or less than the current value C _lmt estimated by the battery allowable current value estimation unit 115, the process ends. On the other hand, when the current value _{C BATT_ALL} the battery supply current value estimation unit 114 estimates exceeds the current value _{C lmt} battery allowable current value estimation unit 115 estimates, at step S25, the fuel cell main relay DC voltage converter The state of the fuel cell main relay 24 and the DC voltage conversion device 25 is confirmed by the off state detection means 112, and it is determined in step S26 whether the fuel cell main relay 24 or the DC voltage conversion device 25 is in an off state. .

  Specifically, the fuel cell main relay / DC voltage converter OFF state detection means 112 has, for example, that the output voltage value of the DC voltage converter 25 detected by the voltage sensor 32 is equal to or lower than a predetermined voltage threshold. Is confirmed, it is determined that the fuel cell main relay 24 or the DC voltage converter 25 is in an OFF state. Further, the fuel cell main relay / DC voltage converter off-state detecting means 112 has an input current value of the DC voltage converter 25 detected by the current sensor 29 and an output current of the DC voltage converter 25 detected by the current sensor 31. When it is confirmed that the value is 0, it may be determined that the fuel cell main relay 24 or the DC voltage converter 25 is in an OFF state.

  If it is determined in step S26 that the fuel cell main relay 24 or the DC voltage converter 25 is off, then in step S27, the vehicle required power is limited by the vehicle required power limiting means 113, and step S28 is performed. , The battery main relay on / off switching means 116 switches the battery main relay 27 to the off state, thereby cutting off the battery / load electric path. Thereby, the extraction of electric power from the battery 21 is forcibly stopped, and the battery 21 and the battery main relay 27 are protected.

  On the other hand, if it is determined in step S26 that the fuel cell main relay 24 or the DC voltage converter 25 is not in the OFF state, the power supply from the fuel cell 1 is continued, and the battery 21 Since excessive electric power is not taken out, the process ends without switching the battery main relay 27 to the off state.

  As described above, in the power supply system of the present embodiment, the fuel cell main relay 24 and the DC voltage converter 25 are turned off for self-protection due to abnormality detection, and the power supply from the fuel cell 1 is cut off. When the battery 21 instantaneously requires excessive power, the battery main relay 27 is switched off by the control of the system controller 100 to cut off the battery / load electric path. Therefore, it is possible to avoid problems such as an increase in power consumption of the battery 21 and deterioration of the battery 21 and the battery main relay 27, which are problems when excessive power is taken out from the battery 21 instantaneously. it can.

In the example described above, even when the battery allowable current value estimation means 115 of the system controller 100 continues energization to the battery main relay 27 for a predetermined time T ₁ substantially equal to one calculation cycle of the system controller 100. Although the maximum current value that does not cause the fuse to blow is estimated as the current value C _{1mt that} can be allowed by the battery 21 and the battery main relay 27, the battery main relay 27 is the _same as in the first embodiment described above. Is set to a minute time ΔT ₁ shorter than one calculation cycle of the system controller 100, and the maximum current that does not cause fuse blown even when the current to the battery main relay 27 is continued during this minute time ΔT _1. Is estimated as an allowable current value for the battery 21 and the battery main relay 27. It may be.

In performing such control, the system controller 100 executes the control flow shown in FIG. 11 instead of the control flow shown in FIG. In the control flow shown in FIG. 11, the processes in steps S31 and S32 are the same as the processes in steps S21 and S22 in the control flow shown in FIG. Further, the processing from step S35 to step S38 in the control flow shown in FIG. 10 is the same as the processing from step S25 to step S28 in the control flow shown in FIG. Then, in step S33, the battery allowable current value estimation unit 115, that lead to blown fuse even when allowed to continue energization of the between the battery main relay 27 one operation shorter than the period minute time of the system controller 100 [Delta] T ₁ The maximum current value that is not _present is estimated as the current value C _{max — lmt} that the battery 21 and the battery main relay 27 can tolerate.

In step S34, the current value C _{BATT_ALL} estimated by the battery supply current value estimation unit 114 in step S32 is compared with the current value _{Cmax_lmt} estimated by the battery allowable current value estimation unit 115 in step S33, and the battery supply current is compared. If the current value _{C BATT_ALL} value estimating unit 114 estimates exceeds the current value _{C Max_lmt} battery allowable current value estimation unit 115 estimates, step S35 following process is performed, the fuel cell main relay 24 or the DC voltage converter When 25 is in the off state, the battery main relay 27 is switched to the off state, and the battery / load electric path is cut off.

  As a result, when there is a low possibility of causing deterioration of the battery 21 or the battery main relay 27, when the possibility of causing deterioration of the battery 21 or the battery main relay 27 is high while continuing to take out power from the battery 21, The extraction of power from the battery 21 can be forcibly stopped to protect the battery 21 and the battery main relay 27.

It is a figure showing an example of 1 composition of a fuel cell power generation system. 1 is a diagram showing an overall configuration of a power supply system for a fuel cell vehicle to which the present invention is applied. It is a functional block diagram which shows each means implement | achieved by the system controller of 1st Embodiment. It is a figure which shows the fuse fusing characteristic of a battery main relay. It is a figure which shows the relationship between the electric power generation amount fall of a fuel cell, and a battery discharge current value, (a) shows a mode that vehicle power demand is restrict | limited when the electric power generation amount of a fuel cell falls, (b) is a system controller It shows how the battery discharge current value increases due to the calculation delay. It is a flowchart which shows an example of the control performed by the system controller of 1st Embodiment. It is a figure which shows the fuse blowing characteristic of a battery main relay, and is a figure explaining the relationship between the energization continuation time to a battery main relay, and an allowable electric current value. It is a flowchart which shows the other example of the control performed by the system controller of 1st Embodiment. It is a functional block diagram which shows each means implement | achieved by the system controller of 2nd Embodiment. It is a flowchart which shows an example of the control performed by the system controller of 2nd Embodiment. It is a flowchart which shows the other example of the control performed with the system controller of 2nd Embodiment.

Explanation of symbols

1 Fuel Cell 21 Battery 22 Drive Motor 24 Fuel Cell Main Relay (Fuel Cell Electrical Path Open / Close Switch)
25 DC voltage converter 27 Battery main relay (battery electric path open / close switch)
DESCRIPTION OF SYMBOLS 100 System controller 101 Vehicle required power calculating means 102 Fuel cell power generation amount fall detecting means 103 Vehicle required power limit means 104 Battery supply current value estimating means 105 Battery allowable current value estimating means 106 Battery main relay on / off switching means 111 Vehicle required power Calculation means 112 Fuel cell main relay / DC voltage converter off state detection means 113 Vehicle required power limit means 114 Battery supply current value estimation means 115 Battery allowable current value estimation means 116 Battery main relay on / off switching means

Claims (7)

A fuel cell vehicle power supply system equipped with a fuel cell as a main power source and a battery as an auxiliary power source,
A fuel cell electrical path opening / closing switch provided in a fuel cell / load electrical path for connecting the fuel cell and a load;
A battery electrical path opening / closing switch provided in a battery / load electrical path for connecting the battery and the load;
A DC voltage converter that converts the electric power generated by the fuel cell into a direct current and outputs the direct current; and
A system controller for controlling the operation of the power supply system,
The system controller is
A vehicle required power calculation means for calculating the total power required by the vehicle and requesting the vehicle required power to the fuel cell and / or the battery;
Vehicle required power limiting means for limiting the vehicle required power requested by the fuel cell and / or the battery by the vehicle required power calculating means;
Battery electrical path opening / closing switch on / off switching means for switching on / off of the battery electrical path opening / closing switch,
When the power supplied from the fuel cell drops by a predetermined amount or more, the vehicle power demand is limited by an amount corresponding to the amount of power supplied from the fuel cell, and the battery electric path opening / closing switch is turned off. A power supply system characterized by performing control to switch off the battery / load electric path. The system controller is
A fuel cell power generation amount decrease detecting means for detecting a power generation amount decrease of the fuel cell;
Battery supply current value estimation for estimating the current value supplied from the battery when it is assumed that the power generation decrease amount of the fuel cell detected by the fuel cell power generation amount decrease detection means is all supplemented by the power from the battery. Means,
A battery allowable current value estimating means for estimating an allowable current value for the battery and the battery electric path opening / closing switch;
When the current value estimated by the battery supply current value estimation means exceeds the current value estimated by the battery allowable current value estimation means, the battery electrical path open / close switch is switched to an off state to switch the battery / load electricity The power supply system according to claim 1, wherein the road is blocked. The system controller is
A fuel cell electrical path on / off switch / DC voltage converter off-state detecting means for detecting that the fuel cell electrical path on / off switch or the DC voltage converter is in an off state;
Battery supply current value estimating means for estimating a current value supplied from the battery, assuming that the vehicle required power calculated by the vehicle required power calculating means is covered by the power from the battery;
A battery allowable current value estimating means for estimating an allowable current value for the battery and the battery electric path opening / closing switch;
The current value estimated by the battery supply current estimation means is estimated by the battery allowable current estimation means when it is detected that the fuel cell electric path opening / closing switch or the DC voltage converter is in an OFF state. 2. The power supply system according to claim 1, wherein when the electric current value exceeds the value, the battery electric path opening / closing switch is switched to an off state to cut off the battery / load electric path.   3. The battery allowable current value estimation means estimates a current value allowable for the battery and the battery electric path opening / closing switch based on a fuse blowing characteristic of the battery electric path opening / closing switch. 4. The power supply system according to 3.   The battery allowable current value estimating means estimates a maximum current value at which the fuse and the battery electric path opening / closing switch can tolerate a maximum value even when energization is continued for a predetermined time. The power supply system according to claim 4.   The power supply system according to claim 5, wherein the predetermined time is a time substantially equal to one calculation cycle of the system control device.   The power supply system according to claim 5, wherein the predetermined time is a minute time shorter than one calculation cycle of the system control device.

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