JP5651531B2 - Fuel cell vehicle - Google Patents

Description

  The present invention relates to a fuel cell vehicle capable of driving a travel motor using a fuel cell and a power storage device.

  A technique for temporarily stopping power generation of a fuel cell in a predetermined case has been proposed (Patent Document 1). In Patent Document 1, when a predetermined temporary stop condition (idle condition) is satisfied, power generation of the fuel cell 1 is stopped to be in a temporary stop state, and when a predetermined return condition (idle return condition) is satisfied, the fuel cell Resume power generation 1 (summary). Further, when the fuel cell 1 is in a paused state, a change in the performance of the fuel cell system is detected, and the return condition is changed in accordance with the change in the performance. Restart (summary).

  Regarding the change in performance of the fuel cell system, in Patent Document 1, the performance of the fuel cell or unit cell is determined using the oxidant gas supply amount, the total voltage of the fuel cell, the cell voltage of the fuel cell, or the atmospheric pressure around the fuel cell vehicle. It determines with having stopped (Claims 4-7). Moreover, in patent document 1, the vehicle speed which is idling return conditions is reduced, so that the performance of a fuel cell system falls (Claim 3). Thereby, it is intended to avoid a decrease in driving performance after restart (return to idle) due to deterioration of the fuel cell system ([0005] to [0009]).

JP 2006-158006 A

  As described above, Patent Document 1 intends to avoid a decrease in operating performance due to deterioration of the fuel cell system. In other words, Patent Document 1 aims to maintain the performance before deterioration even if the fuel cell system deteriorates.

  By the way, in a fuel cell vehicle, in general, a battery as an auxiliary power source is provided in addition to a fuel cell as a main power source. However, when considering the fuel consumption of the entire fuel cell vehicle, charging of the battery (power storage device) is necessary. It is necessary to consider the discharge efficiency. However, Patent Literature 1 does not consider idle return focusing on fuel consumption of the entire fuel cell vehicle. In addition, Patent Document 1 does not consider idle stop focusing on the fuel consumption of the entire fuel cell vehicle.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a fuel cell vehicle capable of improving fuel efficiency while preventing shortage of supplied power.

  A fuel cell vehicle according to the present invention includes a travel motor, a fuel cell that supplies power to the travel motor, a power storage device that supplies power to the travel motor and charges regenerative power from the travel motor, A reaction gas supply means for supplying a reaction gas to the fuel cell; a vehicle speed measurement means for measuring the vehicle speed; a possible output detection means for detecting a possible output of the power storage device; and the vehicle speed is equal to or lower than a first vehicle speed threshold value. A first idle power generation suppression unit that performs idle power generation suppression that reduces the amount of operation of the reaction gas supply unit than during normal operation; and the vehicle speed is equal to or lower than a second vehicle speed threshold value that is higher than the first vehicle speed threshold value. A second idle power generation suppression means for performing idle power generation suppression; and the idle power generation suppression means using the first idle power generation suppression means when the possible output of the power storage device is relatively small. Idle power generation suppression vehicle speed threshold value changing means for performing suppression and implementing the idle power generation suppression using the second idle power generation suppression means when the possible output of the power storage device is relatively large. . Note that the idle power generation suppression means that power generation is performed at a power generation amount lower than the lower limit power generation amount during normal power generation (the lower limit value of the power generation amount control range) or power generation is stopped.

  According to this invention, when the possible output of the power storage device is relatively large, it is possible to suppress idle power generation at a higher vehicle speed. As a result, it is possible to suppress power generation of the fuel cell and improve fuel efficiency. Further, since it is determined whether or not it is necessary to suppress idle power generation based on the vehicle speed threshold value, it is possible to realize idle power generation suppression regardless of the power generation state of the fuel cell, and to surely improve fuel consumption.

  The idle power generation suppression vehicle speed threshold changing unit performs the idle power generation suppression by the first idle power generation suppression unit when a difference obtained by subtracting the power consumption of the air conditioner from the possible output of the power storage device is relatively small. The idle power generation suppression may be performed by the second idle power generation suppression means when the difference is relatively large. Thereby, the selection of the first idle power generation suppression means and the second idle power generation suppression means, that is, the switching of the vehicle speed threshold value for performing the idle power generation suppression is based on the difference between the possible output of the power storage device and the power consumption of the air conditioner. Can be done. By taking into account the power consumption of the air conditioner, it is possible to accurately determine the assist amount of the traveling motor by the power storage device. Therefore, it is possible to appropriately switch the vehicle speed threshold at which idle power generation suppression is to be performed.

  The vehicle speed at which the second idle power generation suppression unit cancels the idle power generation suppression may be higher than the vehicle speed at which the first idle power generation suppression unit cancels the idle power generation suppression. According to the above, when the possible output of the power storage device is relatively large, it is possible to cancel the idle power generation suppression at a higher vehicle speed. As a result, it is possible to suppress power generation of the fuel cell and improve fuel efficiency. Further, since it is determined whether or not it is necessary to cancel the idle power generation suppression based on the vehicle speed threshold, it is possible to cancel the idle power generation suppression regardless of the power generation state of the fuel cell, and to surely improve the fuel consumption.

  The possible output of the power storage device may be calculated based on the remaining capacity and temperature of the power storage device. Thus, the possible output of the power storage device is calculated based on not only the remaining capacity of the power storage device but also the temperature of the power storage device, so that the possible output of the power storage device can be determined with high accuracy. Therefore, it is possible to prevent a malfunction (for example, a decrease in charge / discharge efficiency of the power storage device and a decrease in power generation efficiency associated therewith) when there is an error in the possible output of the power storage device.

  The fuel cell vehicle includes a converter that controls the output voltage of the fuel cell by transforming the output voltage of the power storage device, and the idle power generation suppression when the possible output of the power storage device is larger than the possible output of the converter The vehicle speed threshold changing means performs the idle power generation suppression by the first idle power generation suppressing means when the possible output of the converter is relatively small, and the second idle power when the possible output of the converter is relatively large. The idle power generation suppression may be performed by a power generation suppression means.

  When the output voltage of the power storage device is transformed by the converter to control the output voltage of the fuel cell, the possible output of the power storage device cannot exceed the possible output of the converter. According to the above configuration, when the possible output of the power storage device is larger than the possible output of the converter, the potential output of the converter is used instead of the possible output of the power storage device and the first idle power generation suppression unit or the second idle power generation suppression unit Make a selection. As a result, it is possible to appropriately select a vehicle speed threshold value for performing idle power generation suppression. Therefore, it is possible to prevent a malfunction (for example, a decrease in charge / discharge efficiency of the power storage device and a decrease in power generation efficiency associated therewith) when there is an error in the possible output of the power storage device.

  A fuel cell vehicle according to the present invention includes a travel motor, a fuel cell that supplies power to the travel motor, a power storage device that supplies power to the travel motor and charges regenerative power from the travel motor, A reactive gas supply means for supplying a reactive gas to the fuel cell; a vehicle speed measuring means for measuring a vehicle speed; a possible output detecting means for detecting a possible output of the power storage device; and the vehicle speed being equal to or higher than a first vehicle speed threshold value. A first idle power generation suppression canceling unit that cancels idle power generation suppression for reducing the amount of operation of the reaction gas supply unit than that during normal operation; and the vehicle speed is equal to or higher than a second vehicle speed threshold that is higher than the first vehicle speed threshold. The second idle power generation suppression canceling means for canceling the idle power generation suppression and the first idle power generation suppression cancellation means when the possible output of the power storage device is relatively small Idle power generation suppression cancellation vehicle speed threshold value changing means for canceling idle power generation suppression and releasing the idle power generation suppression using the second idle power generation suppression cancellation means when the possible output of the power storage device is relatively large. It is characterized by.

  According to this invention, when the possible output of the power storage device is relatively large, it is possible to release the idle power generation suppression at a higher vehicle speed. As a result, it is possible to suppress power generation of the fuel cell and improve fuel efficiency. Further, since it is determined whether or not it is necessary to cancel the idle power generation suppression based on the vehicle speed threshold value, it is possible to cancel the idle power generation suppression regardless of the power generation state of the fuel cell and to surely improve the fuel consumption.

  According to this invention, when the possible output of the power storage device is relatively large, it is possible to suppress idle power generation at a higher vehicle speed. As a result, it is possible to suppress power generation of the fuel cell and improve fuel efficiency. Further, since it is determined whether or not it is necessary to suppress idle power generation based on the vehicle speed threshold value, it is possible to realize idle power generation suppression regardless of the power generation state of the fuel cell, and to surely improve fuel consumption.

  Further, according to the present invention, when the possible output of the power storage device is relatively large, it is possible to cancel the idle power generation suppression at a higher vehicle speed. As a result, it is possible to suppress power generation of the fuel cell and improve fuel efficiency. Further, since it is determined whether or not it is necessary to cancel the idle power generation suppression based on the vehicle speed threshold value, it is possible to cancel the idle power generation suppression regardless of the power generation state of the fuel cell and to surely improve the fuel consumption.

1 is a schematic configuration diagram of a fuel cell vehicle according to an embodiment of the present invention. It is a figure which shows the detail of the DC / DC converter in the said embodiment. It is a figure explaining the function which an electronic control unit (ECU) realizes. It is a flowchart of the start determination of idle stop. It is a figure which shows the relationship between a battery remaining capacity (SOC) and a battery possible output for every battery temperature. It is a figure which shows the relationship between converter temperature and converter possible output. It is a figure which shows the relationship between the assist upper limit of a battery, and an idle stop start vehicle speed. It is a flowchart of cancellation | release determination of idle stop. It is a figure which shows the relationship between the said assist upper limit and idle stop cancellation | release vehicle speed. It is a time chart regarding the start determination and cancellation | release determination of idle stop by the magnitude of the amount of assist. It is a figure which shows the relationship between the vehicle speed (idle stop vehicle speed) which performs an idle stop, and the idle stop time in one idle stop mode. It is a figure which shows the relationship between an idle stop vehicle speed and the fuel consumption in one idle stop mode. It is a block diagram which shows schematic structure of the 1st modification of the electric power system which concerns on the said embodiment. It is a block diagram which shows schematic structure of the 2nd modification of the electric power system which concerns on the said embodiment. It is a block diagram which shows schematic structure of the 3rd modification of the electric power system which concerns on the said embodiment.

1. Explanation of overall configuration [1-1. overall structure]
FIG. 1 is a schematic configuration diagram of a fuel cell vehicle 10 (hereinafter referred to as “FC vehicle 10” or “vehicle 10”) according to an embodiment of the present invention. The FC vehicle 10 includes a vehicle power supply system 12 (hereinafter also referred to as “power supply system 12”), a traveling motor 14, and an inverter 16.

  The power supply system 12 includes a fuel cell unit 18 (hereinafter referred to as “FC unit 18”), a battery 20, a DC / DC converter 22, an electronic control device 24 (hereinafter referred to as “ECU 24”) (vehicle speed measuring means), and Have

[1-2. Drive system]
The motor 14 generates a driving force based on the electric power supplied from the FC unit 18 and the battery 20, and rotates the wheels 28 through the transmission 26 by the driving force. Further, the motor 14 outputs electric power (regenerative power Preg) [W] generated by performing regeneration to the battery 20. The regenerative power Preg may be output to an auxiliary machine group (including an air pump 36, a water pump 68, an air conditioner 140, and a low voltage auxiliary machine group 144 described later).

  The inverter 16 has a three-phase full-bridge configuration, performs DC / AC conversion, converts DC to three-phase AC, and supplies it to the motor 14. On the other hand, the inverter 16 receives DC after AC / DC conversion accompanying the regenerative operation. Is supplied to the battery 20 and the auxiliary machine group through the DC / DC converter 22.

  The motor 14 and the inverter 16 are collectively referred to as a load 30. However, the load 30 may include components such as an air pump 36, a water pump 68, an air conditioner 140, and a low voltage auxiliary machine group 144, which will be described later.

[1-3. FC unit 18]
The fuel cell stack 32 of the FC unit 18 (hereinafter referred to as “FC stack 32” or “FC32”) is, for example, a fuel cell (a battery cell formed by sandwiching a solid polymer electrolyte membrane from both sides with an anode electrode and a cathode electrode ( (Hereinafter referred to as “FC cell” or “single cell”). A hydrogen tank 34 and an air pump 36 are connected to the FC stack 32 through paths 38 and 40, and hydrogen (fuel gas), which is one reaction gas from the hydrogen tank 34, and the other reaction gas from the air pump 36. Some compressed air (oxidant gas) is supplied. The hydrogen and air supplied from the hydrogen tank 34 and the air pump 36 to the FC stack 32 cause an electrochemical reaction in the FC stack 32 to generate power, and the generated power (FC power Pfc) [W] is generated from the motor 14 and the battery. 20 is supplied.

  The power generation voltage (hereinafter referred to as “FC voltage Vfc”) [V] of the FC stack 32 is detected by the voltage sensor 42, and the power generation current (hereinafter referred to as “FC current Ifc”) [A] of the FC stack 32 is a current. Detected by the sensor 44 and output to the ECU 24, respectively. Further, the generated voltage (hereinafter referred to as “cell voltage Vcell”) [V] of each FC cell constituting the FC stack 32 is detected by the voltage sensor 46 and output to the ECU 24.

  A regulator 50 is provided in a path 38 connecting the hydrogen tank 34 and the FC stack 32. A path 52 branched from the path 40 connecting the air pump 36 and the FC stack 32 is connected to the regulator 50, and compressed air from the air pump 36 is supplied to the regulator 50. The regulator 50 adjusts the flow rate of hydrogen supplied to the FC stack 32 by changing the opening of the valve according to the pressure of the supplied compressed air.

  The hydrogen path 54 and the air path 56 provided on the outlet side of the FC stack 32 are provided with a purge valve 58 that discharges hydrogen on the outlet side to the outside and a back pressure valve 60 that adjusts the air pressure. ing. Further, a path 62 connecting the path 38 on the hydrogen inlet side and the path 54 on the outlet side is provided. The hydrogen discharged from the FC stack 32 is returned to the inlet side of the FC stack 32 through this path 62. Pressure sensors 64 and 66 are provided in the outlet-side paths 54 and 56, and the detected values (pressure values) are output to the ECU 24, respectively.

  Further, a water pump 68 for cooling the FC stack 32 is provided in the FC stack 32.

[1-4. Battery 20]
The battery 20 is a power storage device (energy storage) including a plurality of battery cells. For example, a lithium ion secondary battery, a nickel hydrogen battery, a capacitor, or the like can be used. In this embodiment, a lithium ion secondary battery is used. The output voltage (hereinafter referred to as “battery voltage Vbat”) [V] of the battery 20 is detected by the voltage sensor 70, and the output current (hereinafter referred to as “battery current Ibat”) [A] of the battery 20 is detected by the current sensor 72. And output to the ECU 24, respectively. The temperature of the battery 20 (hereinafter referred to as “battery temperature Tbat”) is detected by a battery temperature sensor 76 (hereinafter also referred to as “temperature sensor 76”) and output to the ECU 24. The ECU 24 calculates the remaining capacity (hereinafter referred to as “SOC”) [%] of the battery 20 based on the battery voltage Vbat from the voltage sensor 70 and the battery current Ibat from the current sensor 72.

[1-5. DC / DC converter 22]
The DC / DC converter 22 supplies FC power Pfc from the FC unit 18, power supplied from the battery 20 (hereinafter referred to as “battery power Pbat”) [W], and regenerative power Preg from the motor 14. To control.

  FIG. 2 shows details of the DC / DC converter 22 in the present embodiment. As shown in FIG. 2, one of the DC / DC converters 22 is connected to the primary side 1S where the battery 20 is located, and the other is connected to the secondary side 2S which is a connection point between the load 30 and the FC stack 32. Yes.

  The DC / DC converter 22 boosts the voltage on the primary side 1S (primary voltage V1) [V] to the voltage (secondary voltage V2) [V] (V1 ≦ V2) on the secondary side 2S and secondary voltage This is a step-up / step-down and chopper-type voltage converter that steps down the voltage V2 to the primary voltage V1.

  As shown in FIG. 2, the DC / DC converter 22 includes a phase arm UA arranged between the primary side 1S and the secondary side 2S, and a reactor 80.

  The phase arm UA includes an upper arm element (upper arm switching element 82 and diode 84) and a lower arm element (lower arm switching element 86 and diode 88). For the upper arm switching element 82 and the lower arm switching element 86, for example, MOSFET or IGBT is adopted.

  Reactor 80 is inserted between the midpoint (common connection point) of phase arm UA and the positive electrode of battery 20, and converts voltage between primary voltage V1 and secondary voltage V2 by DC / DC converter 22. In particular, it has the function of releasing and storing energy.

  The upper arm switching element 82 is turned on by the high level of the gate drive signal (drive voltage) UH output from the ECU 24, and the lower arm switching element 86 is turned on by the high level of the gate drive signal (drive voltage) UL. Is done.

  The ECU 24 detects the primary voltage V1 with a voltage sensor 90 provided in parallel with the smoothing capacitor 92 on the primary side, and detects the primary current (primary current I1) [A] with the current sensor 94. To do. Further, the ECU 24 detects the secondary voltage V2 by the voltage sensor 96 provided in parallel with the secondary-side smoothing capacitor 98, and detects the secondary-side current (secondary current I2) [A] by the current sensor 100. To do.

  The temperature of DC / DC converter 22 (hereinafter referred to as “converter temperature Tcon”) is detected by converter temperature sensor 102 (hereinafter referred to as “temperature sensor 102”) (FIG. 1) and is output to ECU 24.

[1-6. ECU 24]
The ECU 24 controls the motor 14, the inverter 16, the FC unit 18, the battery 20, and the DC / DC converter 22 via the communication line 104. In this control, a program stored in a memory (ROM) is executed, and voltage sensors 42, 46, 70, 90, 96, current sensors 44, 72, 94, 100, pressure sensors 64, 66, temperature sensors Detection values of various sensors such as 76 and 102 are used.

  The various sensors here include an opening sensor 110 and a rotation speed sensor 112 (FIG. 1). The opening sensor 110 detects the opening of the accelerator pedal 116 (hereinafter referred to as “accelerator opening θ” or “opening θ”) [degree]. The rotational speed sensor 112 detects the rotational speed of the motor 14 (hereinafter referred to as “motor rotational speed Nm” or “rotational speed Nm”) [rpm]. Further, a main switch 118 (hereinafter referred to as “main SW 118”) is connected to the ECU 24. The main SW 118 switches whether power can be supplied from the FC unit 18 and the battery 20 to the motor 14 and can be operated by the user.

  The ECU 24 includes a microcomputer (arithmetic unit) and has input / output interfaces such as a timer, an A / D converter, and a D / A converter as necessary. Note that the ECU 24 is not limited to only one ECU, but can be composed of a plurality of ECUs for each of the motor 14, the FC unit 18, the battery 20, and the DC / DC converter 22.

  The ECU 24 is required for the power supply system 12 as a whole of the FC vehicle 10 determined based on inputs (load requests) from various switches and various sensors in addition to the state of the FC stack 32, the state of the battery 20, and the state of the motor 14. From the load, the load to be borne by the FC stack 32, the load to be borne by the battery 20, and the distribution (sharing) of the load to be borne by the regenerative power source (motor 14) are determined while arbitrating, and the motor 14, inverter 16 , Sends a command to the FC unit 18, the battery 20 and the DC / DC converter 22.

  FIG. 3 is a diagram for explaining functions realized by the ECU 24. As shown in FIG. 3, the ECU 24 of this embodiment includes a normal power generation function 120 and an idle stop control function 122. The normal power generation function 120 is a function for controlling a normal power generation mode to be described later. The idle stop control function 122 is a function for controlling an idle stop mode, which will be described later, and further includes a possible output detection function 124, a first idle power generation suppression function 126, a second idle power generation suppression function 128, and an idle power generation suppression vehicle speed threshold change function. 130.

  The possible output detection function 124 is a function that detects (calculates) the battery possible output Pbat_e, the assistable amount Pasi_e and the assist upper limit value Pasi_lim based on the battery possible output Pbat_e (about the battery possible output Pbat_e, the assistable amount Pasi_e, and the assist upper limit value Pasi_lim). Will be described later.) The first idle power generation suppression function 126 is a function for controlling idle stop when the assist upper limit value Pasi_lim is low. The second idle power generation suppression function 128 is a function for controlling idle stop when the assist upper limit value Pasi_lim is high. The idle power generation suppression vehicle speed threshold value changing function 130 is a function for selecting the first idle power generation suppression function 126 and the second idle power generation suppression function 128. Details of these functions 120, 122, 124, 126, 128, and 130 will be described later.

[1-7. Air conditioner 140]
As shown in FIG. 1, the vehicle 10 further includes an air conditioner 140. The air conditioner 140 adjusts the temperature in the vehicle 10 and operates based on a command from the ECU 24, and electric power at that time is obtained from at least one of the FC 32, the battery 20, and the motor 14. As the air conditioner 140, for example, the one described in JP 2009-046020 A can be used.

[1-8. Downverter 142 and low voltage auxiliary machine group 144]
As shown in FIG. 1, the vehicle 10 further includes a downverter 142 (hereinafter also referred to as “DV142”) and a low-voltage auxiliary machine group 144. The output from the DV 142 may be output to a low voltage battery (not shown). The DV 142 steps down the primary voltage V 1 of the DC / DC converter 22 and outputs it to the low voltage auxiliary machine group 144. The low voltage auxiliary machine group 144 includes, for example, lights, various sensors, and the ECU 24.

2. Control of this Embodiment Next, the control in ECU24 is demonstrated.

[2-1. FC32 output control]
Due to the characteristics of FC32, FC voltage Vfc is basically equal to secondary voltage V2 of DC / DC converter 22. Therefore, the FC voltage Vfc can be controlled by adjusting the secondary voltage V2 by the DC / DC converter 22. Further, the FC current Ifc can be controlled by controlling the FC voltage Vfc on the current-voltage (IV) characteristics of the FC32. Therefore, in the present embodiment, the FC voltage Vfc and the FC current Ifc are controlled using a target value of the secondary voltage V2 (hereinafter referred to as “target secondary voltage V2tgt”).

[2-2. Power generation mode]
In the present embodiment, the normal power generation mode and the idle stop mode are used as the operation mode (power generation mode) related to the power generation of the FC 32. The normal power generation mode is a mode used in normal travel (travel that is not the idle stop mode), and is realized by the normal power generation function 120 of the ECU 24. The idle stop mode is a mode in which the FC 32 actively stops power generation (in other words, suppresses power generation of the FC 32) in a state where the main SW 118 (FIG. 1) is on, and is realized by the idle stop control function 122. The positive power generation (or suppression of power generation) here refers to power generation of the FC 32 based on a command from the ECU 24, and does not include power generation by residual gas. For this reason, the operation amount of the FC unit 18 (including the air pump 36, the purge valve 58, and the back pressure valve 60) as the reaction gas supply means becomes zero. The normal power generation mode and the idle stop mode are selected by the idle stop control function 122.

[2-3. Idle stop start determination]
FIG. 4 is a flowchart of start determination of idle stop. In step S1, the ECU 24 calculates a possible output of the battery 20 (hereinafter referred to as “battery possible output Pbat_e”) [W] based on the SOC of the battery 20 and the battery temperature Tbat from the battery temperature sensor 76. The battery possible output Pbat_e indicates electric power that can be output by the battery 20 at the current SOC and battery temperature Tbat.

  FIG. 5 is a diagram illustrating the relationship between the SOC and the battery possible output Pbat_e for each battery temperature Tbat. As shown in FIG. 5, the battery possible output Pbat_e increases as the SOC increases. Further, under normal use range conditions, when the SOC is the same value, the battery possible output Pbat_e increases as the battery temperature Tbat increases. Note that FIG. 5 shows only when the battery temperature Tbat is high and low, but stores a map storing the data of the SOC and the battery possible output Pbat_e for each battery temperature Tbat in a storage device (not shown) of the ECU 24. In addition, the data is used.

In step S2, the ECU 24 calculates an assistable amount Pasi_e [W]. The assistable amount Pasi_e indicates an assist amount that the battery 20 can obtain, and is obtained by the following equation (1).
Pasi_e = battery possible output Pbat_e−air conditioner consumption−DV consumption (1)

  In the above formula (1), “air conditioner consumption” is the consumption of the air conditioner 140, and “DV consumption” indicates the consumption of the downverter 142.

  In step S3, the ECU 24 calculates a convertible output Pcon_e [W]. The convertible output Pcon_e indicates power that can be output by the DC / DC converter 22 at the current converter temperature Tcon. FIG. 6 is a diagram illustrating a relationship between the converter temperature Tcon and the convertible output Pcon_e. As shown in FIG. 6, the converter possible output Pcon_e decreases as the converter temperature Tcon increases. 6 is stored in advance in the storage device of the ECU 24.

  In step S4 of FIG. 4, the ECU 24 determines whether or not the assistable amount Pasi_e is equal to or greater than the convertible output Pcon_e. This is because when the assistable amount Pasi_e exceeds the convertible output Pcon_e, the excess cannot be output. When the assistable amount Pasi_e is equal to or greater than the converter-capable output Pcon_e (S4: YES), in step S5, the ECU 24 sets the converter-capable output Pcon_e as the assist upper limit value Pasi_lim [W]. When the assistable amount Pasi_e is not equal to or greater than the convertible output Pcon_e (S4: NO), in step S6, the ECU 24 sets the assistable amount Pasi_e as the assist upper limit value Pasi_lim. The assist upper limit value Pasi_lim indicates the assist amount that the battery 20 can actually output in consideration of the output performance of the DC / DC converter 22 (convertible output Pcon_e).

  In step S7, the ECU 24 calculates the idle stop start vehicle speed Vis based on the assist upper limit value Pasi_lim set in step S5 or S6. The idle stop start vehicle speed Vis is a vehicle speed V [km / h] at which the idle stop is started. The vehicle speed V is calculated by the ECU 24 based on the motor rotation speed Nm. FIG. 7 is a diagram illustrating a relationship between the assist upper limit value Pasi_lim and the idling stop start vehicle speed Vis. As shown in FIG. 7, the idling stop start vehicle speed Vis is increased as the assist upper limit value Pasi_lim is increased. Note that the data of FIG. 7 is stored in advance in the storage device of the ECU 24.

  In step S8 in FIG. 4, the ECU 24 determines whether or not the vehicle speed V is equal to or lower than the idle stop start vehicle speed Vis calculated in step S7. When the vehicle speed V is not equal to or lower than the idle stop start vehicle speed Vis (S8: NO), in step S9, the ECU 24 continues normal power generation without starting the idle stop. When the vehicle speed V is equal to or lower than the idle stop start vehicle speed Vis (S8: YES), in step S10, the ECU 24 ends the normal power generation and starts the idle stop.

[2-4. Idle stop release determination]
FIG. 8 is a flowchart of idle stop release determination. Steps S21 to S26 are the same as steps S1 to S6 in FIG.

  In step S27, the ECU 24 calculates the idle stop cancellation vehicle speed Vif based on the assist upper limit value Pasi_lim set in step S25 or S26. The idle stop cancellation vehicle speed Vif is a vehicle speed V at which the idle stop is canceled. FIG. 9 is a diagram illustrating a relationship between the assist upper limit value Pasi_lim and the idle stop release vehicle speed Vif. As shown in FIG. 9, the idling stop start vehicle speed Vis increases as the assist upper limit value Pasi_lim increases. Further, when the assist upper limit value Pasi_lim is the same value, the idle stop release vehicle speed Vif is set higher than the idle stop start vehicle speed Vis. Thereby, it is possible to realize a hysteresis characteristic and prevent the normal power generation mode and the idle stop mode from being switched excessively. Note that the data of FIG. 9 is stored in advance in the storage device of the ECU 24.

  In step S28 of FIG. 8, the ECU 24 determines whether or not the vehicle speed V is equal to or higher than the idle stop release vehicle speed Vif calculated in step S27. If the vehicle speed V is not equal to or higher than the idle stop cancellation vehicle speed Vif (S28: NO), in step S29, the ECU 24 continues the idle stop without releasing the idle stop. When the vehicle speed V is equal to or higher than the idle stop cancellation vehicle speed Vif (S28: YES), in step S30, the ECU 24 cancels the idle stop and resumes normal power generation.

[2-5. Example of control]
FIG. 10 is a time chart regarding the start determination and release determination of idle stop depending on the assistable amount Pasi_e. As described above, when the assist upper limit value Pasi_lim is high, the idle stop start vehicle speed Vis and the idle stop release vehicle speed Vif are set high, and when the assist upper limit value Pasi_lim is low, the idle stop start vehicle speed Vis and the idle stop release vehicle speed Vif are low. Is set. When the assist upper limit value Pasi_lim is the same value, the idle stop release vehicle speed Vif is set to be higher than the idle stop start vehicle speed Vis and has a hysteresis characteristic.

  When the assist upper limit value Pasi_lim is high and the assistable amount Pasi_e of the battery 20 is large, the vehicle speed V becomes equal to or lower than the idle stop start vehicle speed Vis (= Vis1) at time t1, and the idle stop is entered. On the other hand, when the assist upper limit value Pasi_lim is low and the assistable amount Pasi_e is small, the vehicle speed V becomes equal to or lower than the idle stop start vehicle speed Vis (= Vis2) at the time point t2 later than the time point t1, and the idle stop is started.

  At time t3, when the accelerator pedal 116 is depressed and the accelerator opening θ increases, the motor consumption [W] starts to increase.

  When the assist upper limit value Pasi_lim is low and the assistable amount Pasi_e is small, the vehicle speed V becomes equal to or higher than the idle stop release vehicle speed Vif (= Vif2) at time t4, and the idle stop is released to return to normal power generation. On the other hand, when the assist upper limit value Pasi_lim is high and the assistable amount Pasi_e is large, the vehicle speed V becomes equal to or higher than the idle stop cancellation vehicle speed Vis (= Vis1) at the time t5 later than the time t4, and the idle stop is canceled and normal power generation is performed. Return.

[2-6. efficiency]
FIG. 11 is a diagram showing a relationship between a vehicle speed V at which an idle stop is performed (hereinafter referred to as “idle stop vehicle speed Vi”) and an idle stop time during one idle stop mode. FIG. 12 is a diagram showing the relationship between the idle stop vehicle speed Vi and the fuel consumption during one idle stop mode. 11 and 12, the idle stop start vehicle speed Vis and the idle stop release vehicle speed Vif are set to the same value (that is, the idle stop vehicle speed Vi). As can be seen from FIG. 11, the idle stop time increases as the idle stop vehicle speed Vi increases. Therefore, as shown in FIG. 12, the higher the idle stop vehicle speed Vi, the better the fuel consumption.

3. As described above, according to the present embodiment, when the assistable amount Pasi_e based on the battery possible output Pbat_e is relatively large, it is possible to perform idle stop at a higher vehicle speed V (FIG. 4). ). Thereby, it becomes possible to suppress the power generation of FC32 and improve fuel consumption. In addition, since it is determined whether or not an idle stop is necessary based on a vehicle speed threshold (idle stop start vehicle speed Vis), it is possible to realize an idle stop regardless of the power generation state of the FC 32 and to surely improve fuel consumption.

  According to the present embodiment, when the assistable amount Pasi_e based on the battery possible output Pbat_e is relatively large, the idle stop can be released at a higher vehicle speed V (FIG. 8). Thereby, it becomes possible to suppress the power generation of FC32 and improve fuel consumption. In addition, since it is determined whether or not it is necessary to cancel the idling stop based on the vehicle speed threshold (idle stop canceling vehicle speed Vif), it is possible to cancel the idling stop regardless of the power generation state of the FC 32 and to surely improve the fuel consumption.

The ECU 24 (idle power generation suppression vehicle speed threshold value changing function 130) is an assistable amount Pasi_e obtained by subtracting the air conditioner consumption amount and the DV consumption amount from the battery possible output Pbat_e.
Is stopped by the first idle power generation suppression function 126, and when the assistable amount Pasi_e is relatively large, the second idle power generation suppression function 128 performs idle stop. Accordingly, the selection of the first idle power generation suppression function 126 and the second idle power generation suppression function 128, i.e., the switching of the vehicle speed threshold value at which the idle stop is performed is changed to the difference between the battery possible output Pbat_e, the air conditioner consumption amount, and the DV consumption amount. Can be done on the basis. By considering the air conditioner consumption (the power consumption of the air conditioner 140), the battery assist amount Pasi can be accurately determined. Therefore, it is possible to appropriately switch the vehicle speed threshold value at which the idle stop is to be performed.

  In the present embodiment, the vehicle speed V (idle stop cancellation vehicle speed Vif) at which the ECU 24 (second idle power generation suppression function 128) cancels idle stop is higher than the vehicle speed V at which the first idle power generation suppression function 126 cancels idle stop. . According to the above, when the battery possible output Pbat_e is relatively large, the idling stop can be canceled at a higher vehicle speed V. Thereby, it becomes possible to suppress the power generation of FC32 and improve fuel consumption. In addition, since it is determined whether or not it is necessary to cancel the idling stop based on the vehicle speed threshold (idle stop canceling vehicle speed Vif), it is possible to cancel the idling stop regardless of the power generation status of the FC32 and to surely improve the fuel consumption. .

  In the present embodiment, the battery possible output Pbat_e is calculated based on the SOC of the battery 20 and the battery temperature Tbat. Thereby, since the battery possible output Pbat_e is calculated based on not only the SOC but also the battery temperature Tbat, the battery possible output Pbat_e can be determined with high accuracy. Therefore, it is possible to prevent a malfunction (for example, a decrease in charge / discharge efficiency of the battery 20 and a decrease in power generation efficiency associated therewith) when there is an error in the battery possible output Pbat_e.

  In this embodiment, when the battery possible output Pbat_e is larger than the converter possible output Pcon_e, the ECU 24 (idle power generation suppression vehicle speed threshold change function 130) causes the first idle power generation suppression function 126 when the converter possible output Pcon_e is relatively small. The idle stop is performed by the second idle power generation suppression function 128 when the converter possible output Pcon_e is relatively large. When the battery voltage Vbat is transformed by the DC / DC converter 22 to control the FC voltage Vfc, the battery possible output Pbat_e cannot exceed the converter possible output Pcon_e. According to the above configuration, when the battery-capable output Pbat_e is larger than the converter-capable output Pcon_e, the first idle power generation suppression function 126 or the second idle power generation suppression function 128 is used by using the converter-capable output Pcon_e instead of the battery-capable output Pbat_e. Make a selection. As a result, it is possible to appropriately select a vehicle speed threshold value for performing idle stop. Therefore, it is possible to prevent a malfunction (for example, a decrease in charge / discharge efficiency of the battery 20 and a decrease in power generation efficiency associated therewith) when there is an error in the battery possible output Pbat_e.

4). Modifications It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted based on the description in this specification. For example, the following configuration can be adopted.

[4-1. Applicable to]
In the said embodiment, although the example which applied the power supply system 12 to the FC vehicle 10 was shown, not only this but the power supply system 12 may be applied to another object. For example, the present invention can also be applied to a mobile body such as an electric assist bicycle, a ship, and an aircraft.

[4-2. Configuration of power supply system 12]
In the above embodiment, the FC 32 and the battery 20 are arranged in parallel, and the DC / DC converter 22 is arranged in front of the battery 20, but the present invention is not limited to this. For example, as shown in FIG. 13, the FC 32 and the battery 20 may be arranged in parallel, and the step-up, step-down or step-up / step-down DC / DC converter 150 may be arranged in front of the FC 32. Alternatively, as shown in FIG. 14, the FC 32 and the battery 20 may be arranged in parallel, and the DC / DC converter 150 may be arranged in front of the FC 32 and the DC / DC converter 22 may be arranged in front of the battery 20. Alternatively, as shown in FIG. 15, the FC 32 and the battery 20 may be arranged in series, and the DC / DC converter 22 may be arranged between the battery 20 and the motor 14.

[4-3. Power generation mode]
(4-3-1. Idle stop mode)
In the above-described embodiment, the idle stop mode in which the target FC current Ifctgt is zero is used. However, the present invention is not limited to this as long as it is an idle power generation suppression mode (mode in which the target FC current Ifctgt is suppressed). For example, a value greater than zero may be set as the target FC current Ifctgt. In other words, during idle stop, the operation amount of the FC unit 18 as the reactive gas supply means may not be zero.

(4-3-2. Conditions for switching between normal power generation mode and idle stop mode)
In the above embodiment, the condition that the vehicle speed V is equal to or lower than the idle stop start vehicle speed Vis (S8 in FIG. 4: YES) is used as the condition for switching from the normal power generation mode to the idle stop mode. For example, the normal power generation mode may be switched to the idle stop mode when the accelerator opening θ is equal to or less than a threshold value indicating that the operation of the accelerator pedal 116 is not performed.

  In the above embodiment, the condition that the vehicle speed V is equal to or higher than the idle stop cancellation vehicle speed Vif (S28 in FIG. 8: YES) is used as the condition (suppression cancellation condition) for switching from the idle stop mode to the normal power generation mode. Absent. For example, the idle stop mode may be switched to the normal power generation mode when the accelerator opening degree θ is equal to or greater than a threshold value indicating that the operation of the accelerator pedal 116 is being performed.

  In the above embodiment, the first idle power generation suppression function 126 and the second idle power generation suppression function 128 are used as the functions for setting the idle stop start vehicle speed Vis and the idle stop cancellation vehicle speed Vif. Three or more may be sufficient. In other words, each of the idle stop start vehicle speed Vis and the idle stop release vehicle speed Vif may have three or more values using a map (see FIGS. 7 and 9).

(4-3-3. Others)
In the above embodiment, the adjustment with the assist upper limit value Pasi_lim is performed for each of the case of switching from the normal power generation mode to the idle stop mode and the case of switching from the idle stop mode to the normal power generation mode. Also good.

  In the above embodiment, the idle stop start vehicle speed Vis and the idle stop release vehicle speed Vif are calculated based on the assist upper limit value Pasi_lim. However, the present invention is not limited to this as long as it is based on at least the battery possible output Pbat_e. For example, at least one of the idle stop start vehicle speed Vis and the idle stop release vehicle speed Vif may be calculated based on the battery possible output Pbat_e itself or the assistable amount Pasi_e.

  In the above embodiment, the assistable amount Pasi_e is a value obtained by subtracting the air conditioner consumption amount and the DV consumption amount from the battery possible output Pbat_e {the above formula (1)}, but is not limited thereto. For example, it may be a value obtained by subtracting the air conditioner consumption from the battery possible output Pbat_e or a value obtained by subtracting the DV consumption from the battery possible output Pbat_e.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell vehicle 14 ... Traveling motor 18 ... Fuel cell unit (reaction gas supply means)
DESCRIPTION OF SYMBOLS 20 ... Battery (electric storage apparatus) 22 ... DC / DC converter 32 ... Fuel cell stack 76 ... Battery temperature sensor 124 ... Possible output detection function (possible output detection means)
126. First idle power generation suppression function (first idle power generation suppression means)
128 ... second idle power generation suppression function (second idle power generation suppression means)
130: Idle power generation suppression vehicle speed threshold change function (idle power generation suppression vehicle speed threshold change means)
140 ... Air conditioner

Claims (6)

A travel motor;
A fuel cell for supplying power to the travel motor;
A power storage device that supplies power to the travel motor and charges regenerative power from the travel motor;
Reactive gas supply means for supplying a reactive gas to the fuel cell;
Vehicle speed measuring means for measuring the vehicle speed;
Possible output detecting means for detecting possible output of the power storage device;
First idle power generation suppression means for performing idle power generation suppression for reducing the amount of operation of the reaction gas supply means when compared with that during normal operation when the vehicle speed is equal to or lower than a first vehicle speed threshold;
Second idle power generation suppression means for performing the idle power generation suppression when the vehicle speed is equal to or lower than a second vehicle speed threshold value higher than the first vehicle speed threshold value;
The idle power generation suppression is performed using the first idle power generation suppression unit when the possible output of the power storage device is relatively small, and the second idle power generation suppression is performed when the possible output of the power storage device is relatively large. A fuel cell vehicle comprising: idle power generation suppression vehicle speed threshold value changing means for performing the idle power generation suppression using a means. The fuel cell vehicle according to claim 1, wherein
The idle power generation suppression vehicle speed threshold changing unit performs the idle power generation suppression by the first idle power generation suppression unit when a difference obtained by subtracting the power consumption of the air conditioner from the possible output of the power storage device is relatively small. When the difference is relatively large, the idle power generation suppression is performed by the second idle power generation suppression means. The fuel cell vehicle according to claim 1 or 2,
The fuel cell vehicle, wherein a vehicle speed at which the second idle power generation suppression unit cancels the idle power generation suppression is higher than a vehicle speed at which the first idle power generation suppression unit cancels the idle power generation suppression. The fuel cell vehicle according to any one of claims 1 to 3,
A possible output of the power storage device is calculated based on a remaining capacity and temperature of the power storage device. In the fuel cell vehicle according to any one of claims 1 to 4,
A converter that controls the output voltage of the fuel cell by transforming the output voltage of the power storage device;
When the possible output of the power storage device is larger than the possible output of the converter, the idle power generation suppression vehicle speed threshold value changing unit is configured to perform the idle power generation by the first idle power generation suppression unit when the possible output of the converter is relatively small. A fuel cell vehicle characterized in that the idle power generation suppression is performed by the second idle power generation suppression means when the possible output of the converter is relatively large. A travel motor;
A fuel cell for supplying power to the travel motor;
A power storage device that supplies power to the travel motor and charges regenerative power from the travel motor;
Reactive gas supply means for supplying a reactive gas to the fuel cell;
Vehicle speed measuring means for measuring the vehicle speed;
Possible output detecting means for detecting possible output of the power storage device;
First idle power generation suppression release means for canceling idle power generation suppression for reducing the amount of operation of the reaction gas supply means less than during normal operation when the vehicle speed is greater than or equal to a first vehicle speed threshold;
A second idle power generation suppression canceling means for canceling the idle power generation suppression when the vehicle speed is equal to or higher than a second vehicle speed threshold higher than the first vehicle speed threshold;
When the possible output of the power storage device is relatively small, the idle power generation suppression is canceled using the first idle power generation suppression cancellation means, and when the possible output of the power storage device is relatively large, the second idle power generation A fuel cell vehicle comprising: idle power generation suppression cancellation vehicle speed threshold value changing means for canceling the idle power generation suppression using suppression cancellation means.

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