Fuel cell vehicles

Abstract

The present disclosure relates to a fuel cell vehicle. An FCV (1) includes an FC system (20) and a battery (40). The FC system (20) includes an FC stack (22) and a boost converter (24) for adjusting the output of the FC stack (22). An FDC-ECU (60) controls the boost converter (24) so ​​that power is supplied from the FC stack (22) to a converter (12) and the SOC of the battery (40) is adjusted to a target SOC. Furthermore, the FDC-ECU (60) reduces the target SOC as the remaining hydrogen in the hydrogen tank (28) decreases.

Description

Technical Field

[0001] The present disclosure relates to a fuel cell vehicle. Background Art

[0002] International Publication No. 2011 / 004493 discloses a fuel cell vehicle equipped with a fuel cell (hereinafter, the fuel cell is referred to as "FC (Fuel Cell)" and the fuel cell vehicle is referred to as "FCV (Fuel Cell Vehicle)"). The FCV has an FC stack and a battery. The battery functions as a storage source for surplus power, a storage source for regenerative energy during regenerative braking, and an energy buffer for load fluctuations associated with acceleration or deceleration of the vehicle.

[0003] In an FCV equipped with an FC and a power storage device such as a battery, there is a large difference in energy between hydrogen as the fuel of the FC and the electricity stored in the power storage device. Generally speaking, the energy of the electricity stored in the power storage device is smaller than that of hydrogen. Therefore, when the fuel (hydrogen) runs out before the state of charge (SOC) of the power storage device, although the vehicle can be driven using the electricity stored in the power storage device, the driving performance will be suddenly greatly limited at the time when the fuel runs out. Summary of the invention

[0004] The present disclosure has been made to solve the above-mentioned problem, and an object of the present disclosure is to prevent the fuel of the FC from being exhausted prematurely and the driving performance from being suddenly and significantly restricted in an FCV including the FC and the power storage device.

[0005] The FCV of the present disclosure includes: a FC system capable of adjusting output; a power storage device; a drive device that receives power from at least one of the FC system and the power storage device to generate running power; and a control device that controls the output of the FC system so that power is supplied from the FC system to the drive device and the SOC of the power storage device is adjusted to a target SOC. The control device reduces the target SOC when the remaining fuel amount of the FC system decreases.

[0006] As described above, when the remaining fuel level is reduced, the target SOC of the power storage device is reduced, thereby supplying power from the power storage device to the drive device as a whole, thereby preventing the FC from being used in priority to the power storage device. Therefore, according to this FCV, it is possible to avoid the FC fuel being exhausted prematurely and the driving performance being suddenly greatly restricted.

[0007] When the remaining fuel amount of FC is lower than a threshold value, the control device may reduce the target SOC as the remaining fuel amount decreases.

[0008] When the SOC decreases as the target SOC decreases, the output of the power storage device is limited, so the driving performance is limited. In this FCV, the target SOC is lowered when the remaining fuel amount is lower than the threshold, so the output of the power storage device is ensured until the remaining fuel amount decreases to the threshold, thereby ensuring sufficient driving performance.

[0009] The control device may lower the target SOC as the remaining fuel amount decreases so that the target SOC reaches a lower limit value when the fuel of the FC system is exhausted.

[0010] This can avoid the situation where one of the FC system and the power storage device cannot output power due to the fuel exhaustion or the SOC reaching the lower limit value first. As a result, it can avoid the running performance being suddenly greatly restricted.

[0011] Alternatively, the FC system includes a tank storing fuel (hydrogen); a FC stack generating electricity using the fuel stored in the tank; and a converter adjusting an output of the FC stack, wherein the power storage device is electrically connected to a power line between the converter and the drive device.

[0012] According to such a configuration, the output of the FC stack and the power storage device can be adjusted by controlling the converter. For example, the output of the power storage device can be increased by reducing the output of the FC stack relative to the driving power. This can prevent the FC fuel from being exhausted prematurely and the driving performance from being suddenly greatly restricted.

[0013] The FCV may further include a charging device that charges the power storage device using a power source external to the vehicle.

[0014] According to this FCV, long-distance traveling is possible using the fuel (hydrogen) stored in the tank and the electric power supplied from outside the vehicle and stored in the power storage device.

[0015] The above and other objects, features, aspects and advantages of the present disclosure will become apparent from the following detailed description when read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a diagram showing the overall configuration of an FCV according to Embodiment 1 of the present disclosure.

[0017] Figure 2 This is a diagram showing the travel modes provided in the FCV.

[0018] Figure 3 This is a diagram showing the basic flow of electric power in the FC mode.

[0019] Figure 4 This is a diagram showing the basic flow of electric power in the FCEV mode.

[0020] Figure 5 This is a diagram showing a comparison between hydrogen energy and the energy of electric power stored in a battery.

[0021] Figure 6 This is a diagram showing the basic flow of electric power in the EV mode.

[0022] Figure 7 It is a diagram showing the basic flow of electric power in the CHG mode.

[0023] Figure 8 This is a flowchart showing an example of a process procedure executed by the FDC-ECU.

[0024] Fig. 9 It means in Figure 8 Flowchart of an example of a method of calculating the target SOC when the traveling mode is the FCEV mode in step S60 of FIG.

[0025] Fig.10 This is a diagram showing changes in the remaining hydrogen level, the target SOC, and the system output upper limit when the running mode is the FCEV mode.

[0026] Fig.11 : is a diagram showing the relationship between the remaining energy of the FC system and the battery and the upper limit of the system output.

[0027] Fig.12 This is a flowchart showing an example of a method of calculating the target SOC when the running mode is the FCEV mode in the second embodiment.

[0028] Fig.13 This is a diagram showing changes in the remaining hydrogen level, the target SOC, and the system output upper limit when the running mode is the FCEV mode in the second embodiment. DETAILED DESCRIPTION

[0029] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that the same reference numerals are given to the same or corresponding parts in the drawings, and their description will not be repeated.

[0030] [Implementation Method 1]

[0031] Figure 1 1 is a diagram showing the overall structure of the FCV 1 according to the first embodiment of the present disclosure. Figure 1 The FCV 1 includes a motor generator (hereinafter referred to as “MG (Motor Generator)”) 10 , an inverter 12 , an FC system 20 , a hydrogen tank 28 , a supply valve 30 , an air filter 32 , and a compressor 34 .

[0032] MG10 is an AC rotating electric machine, for example, a three-phase AC synchronous motor with a permanent magnet embedded in the rotor. MG10 is driven by the inverter 12 to generate a rotational driving force. The driving force generated by MG10 is transmitted to a driving wheel not shown. When the FCV1 is braked, MG10 operates as a generator to generate electricity. The electric power generated by MG10 is rectified by the inverter 12 and stored in the battery 40.

[0033] Inverter 12 is provided between power line 70 and MG 10, and drives MG 10 based on a drive signal from MG-ECU 66 (described later). Inverter 12 is formed of, for example, a bridge circuit including three-phase switching elements.

[0034] The FC system 20 includes an FC stack 22, a boost converter 24, and a relay 26. The FC stack 22 is, for example, a structure in which a plurality (e.g., tens to hundreds) of solid polymer-type single cells are stacked in series. Each single cell is, for example, formed by bonding catalyst electrodes to both sides of an electrolyte membrane and sandwiching the electrolyte membrane between conductive separators, and hydrogen supplied to the anode and oxygen (air) supplied to the cathode undergo an electrochemical reaction to generate electricity.

[0035] The boost converter 24 boosts the power generated by the FC stack 22 (for example, several hundred volts) based on a control signal from the FDC-ECU 60 (described later) and outputs it to the power line 70. The relay 26 is provided in the circuit between the FC stack 22 and the boost converter 24, and is disconnected when the vehicle system is stopped and the FC system 20 is not in use.

[0036] The hydrogen tank 28 stores fuel hydrogen supplied to the FC stack 22. The hydrogen tank 28 is a lightweight, high-strength high-pressure tank including a carbon fiber reinforced plastic layer, for example, and can store hydrogen at, for example, several tens of MPa. Hydrogen is supplied from the hydrogen tank 28 to the FC stack 22 via a supply valve 30.

[0037] The compressor 34 is a device for supplying oxygen to the FC stack 22. The compressor 34 sucks oxygen (air) through the air filter 32, compresses the air, and supplies the air to the FC stack 22.

[0038] The FCV 1 further includes a battery 40 , a DC (Direct Current) inlet 44 , an AC (Alternate Current) inlet 48 , a charger 50 , and relays 42 , 46 , and 52 .

[0039] The battery 40 is a storage device configured to be chargeable and dischargeable. The battery 40 includes a battery pack composed of a plurality of battery cells (e.g., several hundred cells). Each battery cell is, for example, a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. It should be noted that a lithium-ion secondary battery is a secondary battery that uses lithium as a charge carrier, and in addition to a general lithium-ion secondary battery in which the electrolyte is a liquid, it can also include a so-called all-solid-state battery that uses a solid electrolyte. Instead of the battery 40, a storage element such as a double-layer capacitor can also be used.

[0040] The battery 40 is connected to the power line 72 via the relay 42, and the power line 72 is connected to the power line 70. The battery 40 stores power for driving the MG 10, and supplies power to the inverter 12 through the power lines 72 and 70. In addition, the battery 40 is charged by receiving power generated by the MG 10 when the FCV 1 is braked, etc. The battery 40 can function as an energy buffer that absorbs load fluctuations associated with the acceleration and deceleration of the FCV 1, or stores power generated by the MG 10 when the FCV 1 is braked, etc.

[0041] In addition, in the present embodiment, the battery 40 can be charged by receiving power supplied from a power source (not shown) outside the vehicle through the DC inlet 44 or the AC inlet 48 (hereinafter, charging of the battery 40 by the power source outside the vehicle will also be referred to as "external charging").

[0042] DC inlet 44 is connected to power line 74 via relay 46, and power line 74 is connected to power line 72. DC inlet 44 is configured as a connector capable of fitting a DC charging cable extending from a charging station or the like outside the vehicle (not shown), receives high-voltage DC power supplied from the charging station or the like, and outputs it to power line 74.

[0043] AC inlet 48 is connected to charger 50 via relay 52. ​​AC inlet 48 is configured to be able to be fitted with a connector of an AC charging cable extending from a charging station or the like outside the vehicle, receives AC power (e.g., system power) supplied from the charging station or the like, and outputs it to charger 50. Charger 50 is connected to power line 74, converts the AC power input from AC inlet 48 into a voltage level of battery 40, and outputs it to power line 74.

[0044] Relay 42 is provided between battery 40 and power line 72, and is closed during system startup of FCV 1 or execution of external charging. Relay 46 is provided between DC inlet 44 and power line 74, and is closed during execution of external charging (DC charging) using DC inlet 44. Relay 52 is provided between AC inlet 48 and charger 50, and is closed during execution of external charging (AC charging) using AC inlet 48 and charger 50.

[0045] As described above, the FCV 1 is a plug-in FCV in which the battery 40 can be charged by a power source external to the vehicle connected to the DC inlet 44 or the AC inlet 48 , and can travel using the electric power stored in the battery 40 by external charging.

[0046] FCV1 also includes FDC-ECU (Electronic Control Unit) 60, mode switch (MD-SW) 62, battery ECU 64 and MG-ECU 66. FDC-ECU 60, battery ECU 64 and MG-ECU 66 are respectively configured to include CPU (Central Processing Unit), memory (ROM (Read Only Memory) and RAM (Random Access Memory)) and input / output buffer (none of which are shown in the figure). CPU expands and executes the program stored in ROM in RAM etc. The program stored in ROM describes the processing to be executed by the corresponding ECU.

[0047] The FDC-ECU 60 calculates the output requested from the FC system 20 (the output power of the FC system 20) based on the running power requested from the FCV 1 and the charge / discharge request from the battery 40, and controls the boost converter 24 so that the FC system 20 outputs the calculated power. It should be noted that the running power requested from the FCV 1 is calculated based on the operation amount of the accelerator pedal and the vehicle speed, etc. In the first embodiment, the running power is calculated by the FDC-ECU 60, but it may be calculated by other ECUs (for example, a vehicle ECU (not shown) that controls the entire vehicle as a whole).

[0048] In addition, the FDC-ECU 60 switches the driving mode according to the setting made by the mode switch 62. The FCV 1 is equipped with the FC system 20 and the battery 40 as power sources, and electric power can be stored in the battery 40. In addition, the FCV 1 according to the first embodiment has four driving modes corresponding to the use method of the FC system 20 and the battery 40, and the user can select the driving mode by operating the mode switch 62. The driving mode will be described in detail later.

[0049] The mode switch 62 is a switch for the user to set the driving mode. The mode switch 62 may be a dedicated switch or may be formed in a touch panel display of a navigation device or the like.

[0050] The battery ECU 64 monitors the voltage, current, temperature, etc. of the battery 40. The voltage, current, temperature, etc. of the battery 40 are detected by various sensors not shown. In addition, the battery ECU 64 calculates the SOC of the battery 40 based on the detected values ​​of the voltage, current, temperature, etc. of the battery 40. The calculated SOC value is sent to the FDC-ECU 60. It should be noted that the calculation of the SOC can also be performed by the FDC-ECU 60 based on the detected values ​​of the voltage, current, temperature, etc. of the battery 40.

[0051] In the FCV 1, the battery 40 is connected to the power line 70 without a converter, and basically, the charge and discharge amount of the battery 40 depends on the difference between the running power requested by the inverter 12 and the MG 10 and the output of the FC system 20. Therefore, by controlling the output of the FC system 20 based on the running power by the FDC-ECU 60, the charge and discharge of the battery 40 and the SOC can be controlled.

[0052] In the FCV 1 according to the first embodiment, the FDC-ECU 60 calculates a target SOC indicating a target SOC according to the running mode. Then, the charge / discharge request amount of the battery 40 is calculated based on the deviation between the SOC and the target SOC so that the SOC of the battery 40 approaches the target SOC, and the FDC-ECU 60 controls the output of the FC system 20 based on the calculated charge / discharge request amount and the running power.

[0053] The target SOC will be described in detail later. It should be noted that various known methods can be used to calculate the SOC, such as a method using an OCV-SOC curve (mapping diagram, etc.) that represents the relationship between OCV (Open Circuit Voltage) and SOC, a method using the cumulative value of the current input and output relative to the battery 40, etc.

[0054] The MG-ECU 66 receives the calculated value of the running power requested to the FCV 1 from the FDC-ECU 60 , generates a signal for driving the MG 10 via the inverter 12 based on the running power, and outputs the signal to the inverter 12 .

[0055] <Explanation of driving modes>

[0056] As described above, the FCV 1 includes the FC system 20 and the battery 40 . Furthermore, in the FCV 1 according to the first embodiment, four travel modes corresponding to the method of using the FC system 20 and the battery 40 are provided.

[0057] Figure 2 2 is a diagram showing the driving mode provided in the FCV 1. Figure 2In the FCV 1 according to the first embodiment, there are four driving modes, namely, “FC mode”, “FCEV mode”, “EV mode”, and “CHG mode”. The user of the FCV 1 can select a desired driving mode from these driving modes using the mode switch 62 .

[0058] Figure 3 This is a diagram showing the basic flow of power in FC mode. Figure 3 The FC mode is a running mode in which the vehicle is basically driven only by the output of the FC system 20 until the fuel (hydrogen) of the FC system 20 is exhausted. It should be noted that after the fuel is exhausted, the vehicle is driven only by the output of the battery 40.

[0059] In the FC mode, in order to travel using only the output of the FC system 20 , the FDC-ECU 60 controls the FC system 20 (boost converter 24 ) based on the traveling power so that the FC system 20 outputs power equivalent to the traveling power (request value) required by the inverter 12 .

[0060] It should be noted that even in the FC mode, when the accelerator pedal is greatly depressed and a large running power is requested, and the running power exceeds the output upper limit Wfc of the FC system 20, the insufficient power is supplied from the battery 40. In addition, when the MG 10 performs regenerative power generation during the braking of the FCV 1, the power generated by the MG 10 is supplied from the inverter 12 to the battery 40. It should be noted that when the SOC of the battery 40 has reached the upper limit, the regenerative power generation performed by the MG 10 is not performed.

[0061] Figure 4 This is a diagram showing the basic flow of power in FCEV mode. Figure 4 The FCEV mode is a characteristic driving mode in the FCV 1 according to the first embodiment, and is a hybrid mode that uses the output of the FC system 20 and the output of the battery 40 in a balanced manner. Specifically, in the FCEV mode, the vehicle travels using both the output of the FC system 20 and the output of the battery 40 in such a manner that the timing when the fuel (hydrogen) of the FC system 20 is exhausted and the timing when the SOC of the battery 40 reaches the lower limit value SL are synchronized.

[0062] In the FCV 1 including the FC system 20 and the battery 40, there is a large difference in energy between hydrogen as the fuel of the FC system 20 and the electric power stored in the battery 40. Specifically, Figure 5 As shown, the energy of the electricity stored in the battery 40 is smaller than that of hydrogen. Therefore, when the fuel (hydrogen) runs out before the SOC of the battery 40, although the vehicle can travel using the electricity stored in the battery 40, the travel performance of the FCV 1 is suddenly greatly limited at the time when the fuel runs out.

[0063] Therefore, in the FCV1 according to the present first embodiment, the FCEV mode is set as one of the driving modes, and the user can select the FCEV mode by using the mode switch 62. In the FCEV mode, the vehicle is driven using both the output of the FC system 20 and the output of the battery 40 so that the fuel of the FC system 20 is not exhausted prematurely and the vehicle is driven using only the output of the battery 40 for the remaining portion. Specifically, as described above, the output of the FC system 20 and the battery 40 are adjusted so that the timing of exhaustion of the fuel of the FC system 20 and the timing of the SOC of the battery 40 reaching the lower limit value SL are synchronized. Thus, the vehicle can be driven using both the output of the FC system 20 and the output of the battery 40 until the energy (fuel and battery) of the FCV1 is exhausted, thereby avoiding the situation in which the fuel of the FC system 20 is exhausted prematurely and the driving performance of the FCV1 is suddenly greatly limited.

[0064] In the FCEV mode, in order to synchronize the timing of the fuel exhaustion of the FC system 20 and the timing of the SOC of the battery 40 reaching the lower limit value, in the FCV 1 according to the first embodiment, the target SOC of the battery 40 is lowered as the remaining hydrogen amount of the hydrogen tank 28 decreases. That is, the target SOC is lowered as the remaining hydrogen amount decreases so that the target SOC reaches the lower limit value when the hydrogen in the hydrogen tank 28 is exhausted. This can prevent the FC system 20 from being used in preference to the battery 40.

[0065] In order to make the SOC follow the target SOC that decreases as the remaining amount of hydrogen decreases and to travel using both the output of the FC system 20 and the output of the battery 40, the FCV 1 performs the following control in the selection of the FCEV mode. That is, the FDC-ECU 60 controls the FC system 20 (boost converter 24) based on the traveling power and the SOC of the battery 40 so that the battery 40 outputs electric power in such a manner that the SOC decreases to the target SOC, and the FC system 20 outputs a surplus amount relative to the power required by the inverter 12, that is, the traveling power (request value).

[0066] It should be noted that even in the FCEV mode, when the accelerator pedal is greatly depressed to request a large running power, and the running power exceeds the output upper limit of the FC system 20, power corresponding to the difference between the SOC and the target SOC is supplied from the battery 40. In addition, when the MG 10 performs regenerative power generation during braking of the FCV 1, the power generated by the MG 10 is supplied from the inverter 12 to the battery 40.

[0067] Figure 6 This is a diagram showing the basic flow of electric power in EV mode. Figure 6The EV mode is a running mode in which the vehicle is basically driven only by the output of the battery 40 without using the fuel (hydrogen) of the FC system 20 .

[0068] It should be noted that even in the EV mode, when the accelerator pedal is depressed greatly to request a large running power, and the running power exceeds the output upper limit Wout of the battery 40, the insufficient power can be output from the FC system 20. In addition, when the MG 10 performs regenerative power generation during braking of the FCV 1, the power generated by the MG 10 is supplied from the inverter 12 to the battery 40.

[0069] Figure 7 is a diagram showing the basic flow of power in CHG mode. Figure 7 The CHG mode is a mode in which, when the SOC of the battery 40 decreases, the battery 40 is actively charged using the output of the FC system 20 to increase the SOC to a predetermined level.

[0070] It should be noted that even in the CHG mode, if the accelerator pedal is stepped on and the running power is requested, the power is supplied from the FC system 20 to the inverter 12. Furthermore, when the accelerator pedal is stepped on heavily and a large running power is requested, the power is supplied from the battery 40 to the inverter 12. Furthermore, when the MG 10 performs regenerative power generation during braking of the FCV 1, the power generated by the MG 10 is supplied from the inverter 12 to the battery 40.

[0071] Figure 8 1 is a flowchart showing an example of a process performed by the FDC-ECU 60. It should be noted that a part of the process may be shared by the battery ECU 64 or the MG-ECU 66, or may be performed by other ECUs (such as the vehicle ECU that controls the entire vehicle as a whole) not shown in the figure. The series of processes shown in the flowchart are repeatedly executed at predetermined intervals.

[0072] Reference Figure 8 The FDC-ECU 60 obtains information such as the accelerator opening, the selected shift position, and the vehicle speed (step S10). The accelerator opening is detected by the accelerator opening sensor, and the vehicle speed is detected by the vehicle speed sensor (both not shown). The rotation speed of the drive shaft or transmission shaft may also be used instead of the vehicle speed.

[0073] Next, the FDC-ECU 60 uses a driving force map indicating the relationship between the requested driving force, the accelerator opening, and the vehicle speed, which is prepared in advance for each shift position, and calculates the requested driving force (torque) based on the information acquired in step S10 (step S20). Then, the FDC-ECU 60 multiplies the calculated requested driving force by the vehicle speed and adds a predetermined power loss to calculate the running power (request value) of the FCV 1 (step S30).

[0074] Next, FDC-ECU 60 calculates the torque of MG 10 based on the required driving force calculated in step S20 (step S40 ). The calculated torque of MG 10 is sent to MG-ECU 66 , which controls inverter 12 so that MG 10 outputs the torque.

[0075] Next, the FDC-ECU 60 acquires the setting of the running mode through the mode switch 62 (step S50). Then, when the running mode is the "FCEV mode", the FDC-ECU 60 calculates the target SOC of the battery 40 (step S60). The calculation method of the target SOC in the FCEV mode will be described later.

[0076] It should be noted that, when the running mode is the "FC mode" or the "EV mode", the target SOC is basically not calculated. When the running mode is the "CHG mode", a preset value or a value set by the user is set as the target SOC.

[0077] Next, the FDC-ECU 60 calculates the charge and discharge request (power) of the battery 40 (step S70). The charge and discharge request amount is calculated based on the SOC and the target SOC of the battery 40. Specifically, a pre-prepared map showing the relationship between the SOC deviation from the target SOC and the charge and discharge request amount is used. When the SOC is higher than the target SOC, the higher the SOC, the larger the positive value (discharge request) is calculated. When the SOC is lower than the target SOC, the lower the SOC, the larger the negative value (charge request) is calculated.

[0078] It should be noted that the charge and discharge request amount has upper and lower limits. Also, in the "FC mode" and "EV mode" where the target SOC is not calculated, the charge and discharge request is not calculated.

[0079] Next, FDC-ECU 60 calculates the output of FC system 20 (step S80 ). Specifically, when the running mode is the “FCEV mode”, the output of FC system 20 is calculated by subtracting the charge / discharge request amount calculated in step S70 from the running power calculated in step S30 .

[0080] It should be noted that when the running mode is the "FC mode", the running power calculated in step S30 is set as the output of the FC system 20. When the running mode is the "EV mode", the output of the FC system 20 is set to 0, and when the running mode is the "CHG mode", the absolute value of the charge / discharge request amount (negative value because it is charging) calculated in step S70 is set as the output of the FC system 20.

[0081] Then, the FDC-ECU 60 controls the boost converter 24 of the FC system 20 so that the output of the FC system 20 becomes the output calculated in step S80 .

[0082] Fig. 9 It means in Figure 8 A flowchart of an example of a method for calculating the target SOC in step S60 when the driving mode is the FCEV mode. Fig. 9 The FDC-ECU 60 acquires the remaining amount of hydrogen in the hydrogen tank 28 (step S110 ). The remaining amount of hydrogen can be calculated based on a detection value of a pressure sensor that detects the pressure in the hydrogen tank 28 , for example.

[0083] Then, the FDC-ECU 60 calculates a target SOC corresponding to the remaining hydrogen amount using the remaining hydrogen amount acquired in step S110 (step S120). Specifically, the FDC-ECU 60 calculates the target SOC so that the target SOC decreases as the remaining hydrogen amount decreases. Then, the FDC-ECU 60 decreases the target SOC in accordance with the decrease in the remaining hydrogen amount so that the target SOC reaches a predetermined SOC lower limit value SL when the hydrogen in the hydrogen tank 28 is exhausted.

[0084] Fig.10 This is a diagram showing the changes in the remaining hydrogen, target SOC, and system output upper limit when the driving mode is FCEV mode. It should be noted that the system output upper limit refers to the output upper limit obtained by adding the output upper limit of the FC system 20 and the output upper limit of the battery 40, and the driving performance (output characteristics) of the FCV1 depends on the system output upper limit.

[0085] Reference Fig.10 , it is assumed that the vehicle starts traveling at time t11 with the hydrogen tank 28 fully filled with hydrogen. The target SOC at this time is S1 (for example, 70%), and the difference between S1 and the SOC lower limit value SL (for example, 20%) is ΔSOC (50% in this example).

[0086] When the remaining hydrogen level decreases during traveling, the target SOC is decreased as described above. Specifically, the target SOC is calculated by the following equation so that the target SOC decreases to the SOC lower limit value SL when the hydrogen is exhausted (when the remaining hydrogen level becomes 0) at time t13.

[0087] Target SOC = Hydrogen remaining amount / Hydrogen full filling amount × ΔSOC + SOC lower limit SL (1)

[0088] It should be noted that, regarding the system output upper limit, the value Ws obtained by adding the output upper limit of the FC system 20 and the output upper limit of the battery 40 is ensured until time t12, thereby ensuring the maximum running performance. Here, the relationship between the system output upper limit and the SOC of the battery 40 is described.

[0089] Fig.11 is a diagram showing the relationship between the remaining energy of the FC system 20 and the battery 40 and the upper limit of the system output. Fig.11 , the horizontal axis represents the energy remaining amount (%) of the FC system 20 and the battery 40, respectively, and the vertical axis represents the system output upper limit (W) obtained by adding the output upper limit of the FC system 20 to the output upper limit of the battery 40. It should be noted that the energy remaining amount on the horizontal axis represents the hydrogen remaining amount (100% is a fully filled state) for the FC system 20, and represents the SOC for the battery 40.

[0090] Reference Fig.11 , the output upper limit Wfc of the FC system 20 is a constant value regardless of the remaining amount of hydrogen. That is, the FC system 20 can output power to the output upper limit Wfc regardless of the remaining amount of hydrogen until the fuel is exhausted. On the other hand, when the SOC is lower than the specified value S2, the output upper limit Wout of the battery 40 decreases as the SOC decreases, and becomes 0 at the lower limit SL. In this way, when the SOC of the battery 40 is lower than the specified value S2, the system output upper limit obtained by adding the output upper limit Wfc of the FC system 20 to the output upper limit Wout of the battery 40 decreases as the SOC decreases.

[0091] Refer again Fig.10 When the target SOC is lower than S2 after time t12, the output upper limit Wout of the battery 40 decreases as the target SOC (≈actual SOC) decreases, thereby the system output upper limit also decreases from the value Ws. Then, at time t13, the hydrogen is exhausted (the hydrogen remaining amount is 0), and the SOC of the battery 40 also reaches the lower limit SL.

[0092] In the first embodiment, after time t12, the system output upper limit gradually decreases, but traveling using both the output of the FC system 20 and the output of the battery 40 is possible until the energy (hydrogen and battery) of the FCV 1 is exhausted.

[0093] On the other hand, when the driving mode is the FC mode, the vehicle is basically driven only by the output of the FC system 20 until the hydrogen is exhausted. Therefore, when the hydrogen is exhausted (this exhaustion is faster than when the driving mode is the FCEV mode), the system output upper limit becomes the output upper limit Wout of the battery 40. Therefore, after the hydrogen is exhausted, the driving performance is greatly limited.

[0094] As described above, in the first embodiment, when the driving mode is the FCEV mode, the target SOC of the battery 40 is reduced as the remaining amount of hydrogen decreases. As a result, the output of the battery 40 is also basically used to generate driving power, so it is possible to suppress the FC from being used in priority to the battery as in the FC mode. Therefore, according to the first embodiment, it is possible to avoid the fuel being exhausted prematurely and the driving performance being suddenly greatly restricted.

[0095] [Implementation Method 2]

[0096] In the second embodiment, the target SOC of the battery 40 is not lowered until the remaining hydrogen level drops to a predetermined value, and when the remaining hydrogen level drops below the predetermined value, the target SOC is lowered as the remaining hydrogen level decreases. This allows the period during which the maximum system output upper limit is ensured, i.e., the period during which the maximum driving performance is ensured, to be longer than in the first embodiment.

[0097] The overall configuration and running mode of the FCV according to the second embodiment are the same as those of the FCV 1 according to the first embodiment. In addition, the overall flow of the processing executed by the FDC-ECU 60 in the FCV according to the second embodiment is also the same as those of the FCV 1 according to the first embodiment. Figure 8 The flowchart shown is the same.

[0098] Fig.12 1 is a flowchart showing an example of a method for calculating the target SOC when the driving mode is the FCEV mode in the second embodiment. Fig. 9 The flowchart shown corresponds to the flowchart shown.

[0099] Reference Fig.12 , FDC-ECU60 obtains the remaining hydrogen amount of the hydrogen tank 28 (step S210). Then, FDC-ECU60 determines whether the remaining hydrogen amount is greater than a threshold value H1 (step S220). The threshold value H1 is a threshold value that specifies the start timing of reducing the target SOC in accordance with the remaining hydrogen amount, and the threshold value H1 can be appropriately designed according to the extent to which the maximum system output upper limit (driving performance) is maintained (the extent to which the maximum system output upper limit is not reduced).

[0100] If it is determined in step S220 that the remaining hydrogen level is greater than the threshold value H1 (YES in step S220), the FDC-ECU 60 sets the target SOC of the battery 40 to S1 (S1>S2) (step S230). Fig.11 As shown, the threshold value S1 of the start timing for lowering the output upper limit Wout of the battery 40 as the SOC decreases is a value higher than the threshold value S2.

[0101] On the other hand, when it is determined in step S220 that the remaining hydrogen amount is less than the threshold value H1 (No in step S220), the FDC-ECU 60 uses the remaining hydrogen amount acquired in step S210 to calculate the target SOC corresponding to the remaining hydrogen amount (step S240). In detail, the FDC-ECU 60 calculates the target SOC in such a manner that the target SOC decreases as the remaining hydrogen amount decreases. Specifically, the target SOC is calculated by the following formula in such a manner that the target SOC decreases to the SOC lower limit value SL when the hydrogen is exhausted (when the remaining hydrogen amount becomes 0) at time t24.

[0102] Target SOC = Hydrogen remaining amount / Threshold value H1×ΔSOC+SOC lower limit value SL (2)

[0103] Fig.13 1 is a diagram showing changes in the remaining hydrogen level, the target SOC, and the system output upper limit when the running mode is the FCEV mode in the second embodiment. Fig.13 This is the same as described in Implementation Example 1. Fig.10 The corresponding figure.

[0104] Reference Fig.13 In this example, the vehicle starts traveling at time t21 with the hydrogen tank 28 fully filled with hydrogen. The target SOC at this time is S1 (e.g., 70%), and the difference between S1 and the SOC lower limit SL (e.g., 20%) is ΔSOC (50% in this example).

[0105] Although the remaining hydrogen amount decreases as the vehicle travels, in the second embodiment, the target SOC is not decreased until the remaining hydrogen amount decreases to the threshold value H1 at time t22. Then, when the remaining hydrogen amount is lower than the threshold value H1 after time t22, the target SOC is decreased as the remaining hydrogen amount decreases. Specifically, the target SOC is calculated based on the above-mentioned formula (2) in such a manner that the target SOC decreases to the SOC lower limit value SL when the hydrogen is exhausted (when the remaining hydrogen amount becomes 0) at time t24.

[0106] When the target SOC is lower than S2 at time t23, the output upper limit Wout of the battery 40 decreases as the target SOC (≈actual SOC) decreases ( Fig.11), whereby the system output upper limit also starts to decrease from the value Ws. Then, at time t24, the hydrogen is exhausted (the hydrogen remaining amount is 0), and the SOC of the battery 40 also reaches the lower limit value SL.

[0107] As described above, when the SOC decreases as the target SOC decreases, and when the SOC is lower than the predetermined value S2, the output of the battery 40 is limited, and the driving performance is limited. At this time, in the second embodiment, the target SOC is lowered when the remaining fuel amount is lower than the threshold value H1. In other words, the target SOC is not lowered until the remaining fuel amount is lower than the threshold value H1. Therefore, according to the second embodiment, sufficient driving performance can be ensured until the remaining fuel amount is lowered to the threshold value H1.

[0108] The embodiments of the present disclosure have been described above, but the embodiments disclosed herein are illustrative in all aspects and are not restrictive. The scope of the present invention is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A fuel cell vehicle comprising: A fuel cell system that can adjust output; Electricity storage device; a driving device that receives electric power from at least one of the fuel cell system and the power storage device to generate running power; and a control device that controls the output of the fuel cell system so that power is supplied from the fuel cell system to the drive device and the state of charge of the power storage device is adjusted to a target state of charge, the control device does not lower the target state of charge until the remaining fuel amount decreases to a threshold value, The control device, when the remaining fuel amount is lower than a threshold value, reduces the target state of charge as the remaining fuel amount decreases, The control device lowers the target state of charge as the remaining amount of fuel decreases so that the target state of charge reaches a lower limit value when the fuel of the fuel cell system is exhausted, The target state of charge is calculated based on a ratio of the remaining fuel amount to the threshold value.

2. The fuel cell vehicle according to claim 1, wherein: The fuel cell system comprises: Tanks, for storing fuel; a fuel cell stack for generating electricity using the fuel stored in the tank; and a converter, adjusting the output of the fuel cell stack, The power storage device is electrically connected to a power line between the converter and the drive device.

3. The fuel cell vehicle according to claim 1 or 2, A charging device is further provided, the charging device charging the power storage device using a power source external to the vehicle.

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