Fuel cell automobile

Abstract

The invention provides a fuel cell vehicle capable of inhibiting reduction of vehicle speed during climbing driving. An FC vehicle (10) is provided with a travel motor (12), an FC unit (16) for outputting power to the travel motor (12), a battery (18) for outputting power to the travel motor (12), and a controller (30), and the controller (30) is configured so as to at least temporarily execute FC protection control for operating the battery (18) at a high output higher than a rated output (PB *) during climbing travel.

Description

Technical Field

[0001] This specification discloses a fuel cell vehicle equipped with a fuel cell and a storage battery. Background Art

[0002] Conventionally, a fuel cell vehicle having a fuel cell and a storage battery has been known. A controller mounted on the fuel cell vehicle controls the ratio among the output power of the fuel cell, the output power of the storage battery, and the regenerative power of the drive motor according to the vehicle condition.

[0003] Such a fuel cell vehicle is disclosed in Patent Document 1. When the fuel cell vehicle of Patent Document 1 detects a long-distance uphill climb, it controls the output distribution of the fuel cell to be larger than that before the detection of the long-distance uphill climb.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2012-244713 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, in the prior art including Patent Document 1, during uphill driving, the output distribution of the fuel cell is made the same as or larger than the output distribution of the storage battery. In this case, the power generation amount of the fuel cell during uphill driving increases. Moreover, if the power generation amount of the fuel cell increases, the temperature of the fuel cell rises accordingly. When the temperature of the fuel cell exceeds a predetermined allowable value, the output of the fuel cell is forcibly restricted. As a result, in the prior art, during uphill driving, there is a case where the power supply to the drive motor becomes insufficient and the vehicle speed decreases.

[0009] Therefore, this specification discloses a fuel cell vehicle capable of suppressing a decrease in vehicle speed during uphill driving.

[0010] Means for Solving the Problems

[0011] The fuel cell vehicle disclosed in this specification includes: a drive motor; a fuel cell that outputs power to the drive motor; a storage battery that outputs power to the drive motor; and a controller configured to perform FC protection control in which the storage battery operates at a high output higher than the rated output at least temporarily during uphill driving.

[0012] By temporarily increasing the output of the storage battery, it is possible to suppress a rise in the temperature of the fuel cell accordingly. As a result, it is possible to avoid output restriction of the fuel cell and effectively suppress a decrease in vehicle speed due to power shortage.

[0013] In this case, when the start of hill climbing is detected, the controller may execute the FC protection control to reduce the output of the battery after a predetermined period of time and increase the output of the fuel cell in conjunction with the reduction in the output of the battery.

[0014] By increasing and decreasing the output of the battery and the output of the fuel cell in conjunction with each other, the output value of the vehicle as a whole can be stabilized.

[0015] Furthermore, the controller may be configured to output from the battery within a range of a predetermined battery output upper limit value and to output insufficient output from the fuel cell, and the controller may be configured to set the battery output upper limit value higher than the rated output of the battery during the FC protection control.

[0016] By setting the battery output upper limit value of the battery, it is possible to prevent the battery from having an excessively high output.

[0017] Furthermore, the controller may be configured to start the FC protection control when the temperature of cooling water of the fuel cell reaches a predetermined threshold temperature during the hill climbing travel.

[0018] By adopting the above-mentioned configuration, it is possible to effectively avoid forced output limitation of the fuel cell, and to effectively suppress a decrease in vehicle speed due to power shortage.

[0019] Furthermore, the controller may be configured to terminate the FC protection control when a predetermined relaxation time has elapsed after the start of the FC protection control, when the temperature of the battery exceeds a predetermined threshold, or when the SOC of the battery falls below a predetermined threshold.

[0020] By adopting the above-mentioned structure, it is possible to effectively prevent the degradation of the battery.

[0021] Effects of the Invention

[0022] According to the fuel cell vehicle disclosed in this specification, a decrease in vehicle speed can be effectively suppressed during climbing travel. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a block diagram showing the structure of an FC vehicle.

[0024] Figure 2 This is a diagram showing changes in altitude, battery output, FC output, FC water temperature, and vehicle speed when an FC vehicle is traveling uphill.

[0025] Figure 3This is a diagram showing other examples of the changes in elevation, battery output, FC output, FC water temperature, and vehicle speed during uphill driving in an FC vehicle.

[0026] Figure 4 This is a flowchart showing the process of power control during uphill driving of an FC vehicle.

[0027] Figure 5 This is a diagram showing the changes in elevation, battery output, FC output, FC water temperature, and vehicle speed during uphill driving in an FC vehicle of a comparative example. Detailed Implementation Manner

[0028] Hereinafter, the structure of the fuel cell vehicle 10 will be described with reference to the accompanying drawings. In addition, hereinafter, "fuel cell" will be abbreviated as "FC". Figure 1 This is a block diagram showing the structure of the FC vehicle 10. As Figure 1 shown, the FC vehicle 10 includes a drive motor 12 for driving, an FC unit 16, a battery 18, a transmission 22, and wheels 24 as main components as a drive system.

[0029] The drive motor 12 is an electric generator that generates driving power based on the supplied power and performs regenerative power generation using the braking force of the vehicle. The power of the drive motor 12 is transmitted to the wheels 24 via the transmission 22. By this power, the wheels 24 rotate, and thus the FC vehicle 10 travels. The converter 14 converts DC power into AC power and supplies it to the drive motor 12. In addition, the converter 14 converts the regenerative power output from the drive motor 12 into DC power and outputs it to the battery 18.

[0030] The FC unit 16 is a device that generates electricity by the electrochemical reaction of hydrogen and oxygen. The FC unit 16 has an FC stack, and the FC stack is formed by stacking a plurality of FC single cells. The FC unit is formed, for example, by sandwiching a solid polymer electrolyte membrane between an anode electrode and a cathode electrode. The generated power of the FC unit 16 is supplied to the drive motor 12 and the battery 18.

[0031] Here, the FC unit 16 generates heat during power generation. If the FC unit 16 becomes excessively hot, it will cause deterioration or damage of the FC unit 16. Therefore, a cooling circuit (not shown) through which cooling water flows is provided in the FC unit 16, and the FC unit 16 is cooled by the cooling water. A temperature sensor 26 for detecting the temperature of the cooling water is provided in the FC unit 16. Hereinafter, the temperature of the cooling water detected by the temperature sensor 26 will be referred to as "FC water temperature Tf".

[0032] The storage battery 18 is an energy storage device capable of charging and discharging electric power. The storage battery 18 is, for example, a lithium-ion secondary battery, a nickel-metal hydride battery, a capacitor, or a combination thereof. The voltage and current of the storage battery 18 are detected by sensors (not shown). The controller 30 calculates the remaining capacity of the storage battery 18, that is, the so-called SOC, based on the detected voltage and current.

[0033] The power distribution device 20 controls the supply destinations of the output power of the FC unit 16, the output power of the storage battery 18, and the regenerative power of the drive motor 12 for traveling. The power distribution device 20 is, for example, a DC / DC converter.

[0034] The controller 30 controls the drive motor 12 for traveling, the inverter 14, the FC unit 16, the storage battery 18, and the power distribution device 20. The controller 30 is a computer physically having a processor 32 and a memory 34. Further, in Figure 1 , the controller 30 is illustrated as a single computer, but the controller 30 may also be configured by combining a plurality of physically separated computers.

[0035] Furthermore, the FC vehicle 10 has a plurality of sensors. The throttle opening sensor 42 detects the opening of the accelerator pedal, that is, the throttle opening θ. The slope sensor 40 detects the slope A of the road surface (that is, the inclination in the longitudinal direction of the vehicle 10). The slope sensor 40 is, for example, a gravity sensor. The vehicle speed sensor 44 detects the vehicle speed V. The controller 30 calculates the required output PR for traveling the vehicle based on the detection values of these sensors. Then, the controller 30 controls the driving of the FC unit 16 and the storage battery 18 so as to supply the required output PR to the drive motor 12 for traveling.

[0036] Here, an upper limit value of the output of the storage battery 18, that is, the storage battery output upper limit value PBmx, is preset for the storage battery 18. The controller 30 controls the driving of the storage battery 18 so that the storage battery output PB does not exceed the storage battery output upper limit value PBmx. The storage battery output upper limit value PBmx is generally a power value that enables the storage battery 18 to operate continuously and stably, that is, the rated output PB*. In addition, in this example, when the FC vehicle 10 is climbing a slope, the storage battery output upper limit value PBmx is temporarily set to a value higher than the rated output PB*, which will be described later.

[0037] Here, when the FC vehicle 10 is climbing a slope, the required output PR increases compared to when traveling on a flat surface. When the outputs of both the storage battery 18 and the FC unit 16 are increased to meet the required output PR, it is possible to impose a limit on the power generation capacity of the FC unit 16 during the slope climbing. Regarding this, refer to Figure 5 for explanation.

[0038] Figure 5It is a graph showing the changes in elevation E, battery output PB, FC output PF, FC water temperature Tf, and vehicle speed V during the uphill driving of the FC vehicle in the comparative example. At Figure 5 In the example of

[0039] By entering the uphill section, the required output PR increases. In order to obtain this required output PR, the FC vehicle in the comparative example drives the battery 18 within the battery output upper limit value PBmx (i.e., the rated output PB*), and outputs the insufficient power from the FC unit 16. In this case, although it varies depending on the vehicle speed V and the slope A, the output of the FC unit 16 often exceeds the rated output PF* of the FC unit 16. As a result, during the uphill driving, the temperature of the cooling water for cooling the FC unit 16, that is, the FC water temperature Tf, may reach the FC water temperature allowable value Tf_mx. At Figure 5 In this case, at time t2, the FC water temperature Tf reaches the FC water temperature allowable value Tf_mx.

[0040] When Tf ≥ Tf_mx, in order to lower the FC water temperature Tf, the controller 30 reduces the FC output PF. Moreover, since the FC output PF is reduced, the power available for the entire vehicle decreases, resulting in a decrease in the vehicle speed V.

[0041] In order to prevent such a decrease in the vehicle speed V during the uphill driving, the FC vehicle 10 disclosed in this specification at least temporarily executes FC protection control during the uphill driving. The FC protection control is the following control: making the battery 18 operate at a high output higher than the rated output PB* and making the FC unit 16 operate at an output not exceeding the rated output PF*. Hereinafter, the power control for uphill driving in the FC vehicle 10 disclosed in this specification will be described in detail.

[0042] Figure 2 It is a graph showing the changes in elevation E, battery output PB, FC output PF, FC water temperature Tf, and vehicle speed V during the uphill driving of the FC vehicle 10 disclosed in this specification. Before the start of uphill driving, the battery output upper limit value PBmx is the same value as the rated output PB* of the battery 18. When starting uphill driving at time t1, the required output PR increases. In order to obtain this required output PR, the controller 30 controls the driving of the battery 18 and the FC unit 16 so that the battery output PB increases within the battery output upper limit value PBmx = PB*, and uses the FC output PF to supplement the shortage. As a result, after time t1, both the battery output PB and the FC output PF temporarily increase.

[0043] Here, when the state where the FC output PF is high continues, as described above, the FC water temperature Tf rises to the FC water temperature permissible value Tf_mx, and the output limitation of the FC unit 16 occurs. Therefore, in this example, when the controller 30 detects the start of hill climbing, it performs FC protection control that temporarily makes the battery output PB higher than the rated output PB* and accordingly suppresses the FC output PF to be small.

[0044] For example, in Figure 2 In the example of FIG. 1 , the controller 30 detects the start of hill climbing at time t2. In this case, the controller 30 starts FC protection control to temporarily change the battery output upper limit value PBmx to the battery output mitigation upper limit value PBmx_up which is higher than the rated output PB*. As a result, the battery output PB rises to the battery output mitigation upper limit value PBmx_up. In addition, as the battery output PB rises, the FC output PF decreases accordingly.

[0045] In addition, the controller 30 may also determine that the vehicle is traveling uphill when the slope A is greater than a predetermined threshold and the vehicle speed V is greater than a predetermined threshold. In addition, as another embodiment, the controller 30 may also determine whether the vehicle is traveling uphill by comparing the current position detected by the GPS with the map information registered in the navigation system.

[0046] Here, of course, if the state where the battery output PB exceeds the rated output PB* continues for a long period of time, problems such as shortening the life of the battery 18 may occur. On the other hand, if the state where the battery output PB* exceeds the rated output PB* is for a short period of time, there is almost no adverse effect on the battery 18. In this example, focusing on such characteristics, when starting the climbing travel, the battery output upper limit value PBmx is made higher than the rated output PB* only during the predetermined relaxation time ta.

[0047] Thus, during the period from time t2 when the start of the hill climbing travel is detected to time t3 after the relaxation time ta has elapsed, the battery output PB is higher than the rated output PB* and the FC output PF is reduced. Thus, the rise in the FC water temperature Tf is suppressed.

[0048] Then, at time t3 after the relaxation time ta has passed, the controller 30 reduces the battery output upper limit value PBmx from the battery output relaxation upper limit value PBmx_up to the rated output PB*. As a result, the battery output PB is reduced to the rated output PB*. In addition, the FC output PF increases in conjunction with the reduction in the battery output PB. And, as the FC output PF increases, the FC water temperature Tf also gradually increases. However, since the FC protection control for operating the battery 18 at a high output is performed in advance, the rise start timing of the FC water temperature Tf in this example is shorter than that in the embodiment shown in FIG. Figure 5The start timing of the increase in [the relevant parameter] is late. As a result, the probability of completing the climbing driving before the FC water temperature Tf reaches the FC water temperature allowable value Tf_mx becomes high. Moreover, thereby, it is possible to effectively suppress the decrease in the vehicle speed V caused by power shortage during the climbing driving.

[0049] In addition, the battery output mitigation upper limit value PBmx_up only needs to be higher than the rated output PB*, and there is no particular limitation. For example, it is 1.2 times, or 1.5 times, or 2 times the rated output PB*. For example, the battery output mitigation upper limit value PBmx_up can also be the same value as the maximum output of the battery 18. This battery output mitigation upper limit value PBmx_up can be a preset fixed value or a variable value that varies according to conditions. In addition, the mitigation time ta only needs to be greater than 0 and is not limited. For example, it is several seconds, or dozens of seconds, or several minutes. The mitigation time ta can be a preset fixed value or a variable value that varies according to conditions. In addition, in this example, the end timing of the FC protection control is judged by the elapsed time, but it can also be determined based on other parameters. For example, when the FC protection control is started, the controller 30 can also detect the temperature or SOC of the battery 18, and end the FC protection control when the temperature exceeds a specified threshold or when the SOC is lower than the specified threshold.

[0050] In addition, in Figure 2 only the FC protection control is executed just after the start of the climbing driving. However, in the case of a long uphill driving, the FC protection control can also be executed multiple times at intervals. For example, in Figure 3 In the example, after the first FC protection control ends at time t3, as the FC output PF increases, the water temperature of the FC water temperature Tf gradually increases. Moreover, at time t4 before the end of the climbing, the FC water temperature Tf reaches the specified threshold temperature Tf_th. It should be noted that Tf_th ≤ Tf_mx. In this case, the controller 30 can also start the FC protection control again with the battery output upper limit value PBmx higher than the rated output PB*. By starting the FC protection control again, it is possible to effectively avoid the forced output limitation of the FC unit 16, suppress power shortage, and further suppress the decrease in the vehicle speed V. In addition, by starting the FC protection control again, the output of the FC unit 16 is suppressed, and the FC water temperature Tf gradually decreases. In addition, in order to protect the battery 18, it is also possible to prohibit the start of the (n + 1)-th FC protection control after the end of the n-th FC protection control until a specified standby time elapses or until the temperature of the battery 18 becomes lower than the specified threshold.

[0051] Figure 4 is a flowchart showing the power control process during the climbing driving of the FC vehicle 10 in this example. AsFigure 4 As shown, for the controller 30, when starting uphill driving, the controller 30 starts the FC protection control (S10). That is, the controller 30 sets the battery output upper limit value PBmx to the battery output relaxation upper limit value PBmx_up which is higher than the rated output PB*. Thus, the battery output PB is higher than the rated output PB*, while on the other hand, the FC output PF decreases, suppressing the rise of the FC water temperature Tf.

[0052] This FC protection control continues until the elapse of a specified relaxation time ta. When the relaxation time ta has elapsed (S12: Yes), the controller 30 ends the FC protection control (S16). That is, the controller 30 reduces the battery output upper limit value PBmx to the rated output PB*. Thus, the battery output PB decreases, and the FC output PF increases accordingly.

[0053] After that, the controller 30 monitors the FC water temperature Tf (S18). Then, when the FC water temperature Tf is equal to or higher than the FC water temperature allowable value Tf_mx (S18: Yes), the controller 30 returns to step S10 and restarts the FC protection control. Thereafter, the same process is repeated until the uphill driving ends.

[0054] From the above description, it can be seen that according to the technology disclosed in this specification, the rise of the FC water temperature Tf can be suppressed, so that the output limitation of the FC unit 16 during uphill driving can be effectively suppressed, and further the decrease of the vehicle speed V caused by power shortage can be suppressed. In addition, the above structures are all examples. As long as the structure described in claim 1 is provided, other structures can also be appropriately changed. For example, in the description so far, the FC protection control is executed immediately after detecting uphill driving. However, the start timing of the FC protection control can also be delayed. That is, it is also possible to perform normal control after detecting uphill driving and start the FC protection control after the FC water temperature Tf reaches a specified temperature.

[0055] Description of Reference Numerals

[0056] 10 Fuel cell vehicle, 12 Driving electric motor, 14 Converter, 16 FC unit, 18 Battery, 20 Power distribution device, 22 Transmission, 24 Wheel, 26 Temperature sensor, 30 Controller, 32 Processor, 34 Memory, 40 Gradient sensor, 42 Throttle opening sensor, 44 Vehicle speed sensor.

Claims

1. A fuel cell vehicle comprising: Electric motor for driving; A fuel cell that outputs electric power to the driving motor; a storage battery that outputs electric power to the driving motor; and Controller, The controller is configured to at least temporarily execute FC protection control for operating the battery at a high output higher than a rated output during hill climbing travel.

2. The fuel cell vehicle according to claim 1, wherein: The controller is configured to execute the FC protection control when the start of hill climbing travel is detected, reduce the output of the battery after a predetermined period of time, and increase the output of the fuel cell in conjunction with the reduction in the output of the battery.

3. The fuel cell vehicle according to claim 1, wherein: The controller is configured to output the battery within a range of a predetermined upper limit of the battery output and to output insufficient output from the fuel cell. The controller is configured to set the battery output upper limit value to be higher than a rated output of the battery during the FC protection control.

4. The fuel cell vehicle according to claim 1, wherein: The controller is configured to start the FC protection control when the temperature of cooling water of the fuel cell reaches a predetermined threshold temperature during the hill climbing travel.

5. The fuel cell vehicle according to claim 1, wherein: The controller is configured to terminate the FC protection control when a predetermined relaxation time has elapsed after the start of the FC protection control, when the temperature of the battery exceeds a predetermined threshold, or when the SOC of the battery falls below a predetermined threshold.

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