JP2013208001A - Fuel cell vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell vehicle which enables both a fuel cell and a power storage device to perform warming-up.SOLUTION: An ECU causes a FC (fuel cell) stack and a battery to be directly connected to each other to cause a voltage conversion operation performed by a DC/DC converter to be stopped, during low-temperature starting of an FC vehicle, and carries out a warming-up mode in this direct connection state. In the warming-up mode, the ECU causes warming-up of the FC stack and the battery to be performed by changing an amount of air supplied from an air pump to the FC stack based on a level of a battery residual amount (SOC). When the warming-up of the FC stack and the battery is completed, the ECU releases the direct connection state of the FC stack and the battery and causes the DC/DC converter to start adjustment of FC voltage.

Description

  The present invention relates to a fuel cell vehicle in which a fuel cell that supplies power to a drive motor and a power storage device that assists the output of the fuel cell are connected in parallel to the drive motor.

  Patent Document 1 discloses that a fuel cell vehicle that operates a drive motor with electric power supplied from a fuel cell causes the fuel cell to warm up when the fuel cell vehicle is started at a low temperature. Patent Document 1 discloses that when a fuel cell needs to be warmed up, the fuel cell generates power at an operating point with low power generation efficiency in IV characteristics (I: current, V: voltage). It is disclosed that the fuel cell is warmed up by increasing the temperature of the fuel cell due to loss.

International Publication No. 2008/047603 Pamphlet

  By the way, in the fuel cell vehicle, a fuel cell and a power storage device that assists the output of the fuel cell are connected in parallel to the drive motor. However, since the technology of Patent Document 1 only warms up the fuel cell when the fuel cell vehicle is started at a low temperature, if the power storage device is not warmed up, the original performance of the fuel cell vehicle is sufficiently improved. It cannot be demonstrated.

  The present invention has been made in consideration of such a problem, and provides a fuel cell vehicle capable of warming up both the fuel cell and the power storage device when the fuel cell vehicle is started at a low temperature. The purpose is to provide.

A fuel cell vehicle according to the present invention includes:
In a fuel cell vehicle in which a fuel cell that supplies power to a drive motor and a power storage device that assists the output of the fuel cell are connected in parallel to the drive motor,
The fuel cell is connected in parallel to the fuel cell by connecting the gas supply means for supplying the gas necessary for power generation in the fuel cell to the fuel cell, the power storage device, and the drive motor. Voltage adjustment means for adjusting the output voltage, and control means for controlling the gas supply means and the voltage adjustment means,
The control means includes
If the remaining capacity of the power storage device is greater than or equal to a first predetermined value when the output voltage is adjusted to a warm-up voltage by the voltage adjusting means when the fuel cell vehicle is started, the gas supply means When the amount of gas supplied to the fuel cell is changed so that the output from the power storage device is prioritized, and the remaining capacity is less than or equal to a second predetermined value lower than the first predetermined value, the gas supply means Performing a warm-up control to change the amount of gas supplied from the fuel cell so that the output from the fuel cell has priority,
When the warm-up of the fuel cell and the power storage device by the warm-up control is completed, the warm-up control is canceled.

  According to this invention, after adjusting the output voltage of the fuel cell to the warm-up voltage by the voltage adjusting means, the fuel cell is changed while changing the gas supply amount based on the size of the remaining capacity. The power storage device is warmed up.

  Specifically, in the present invention, when the fuel cell vehicle is started, the output voltage of the fuel cell is adjusted to a voltage lower than the output voltage during normal operation of the fuel cell vehicle (the voltage during warm-up). To do.

  In the warm-up control, in the state where the output voltage is adjusted to the voltage at the time of warm-up, when the remaining capacity is equal to or greater than the first predetermined value, priority is given to the output from the power storage device. By changing the gas supply amount as described above, the assist of the fuel cell by the power storage device is increased. On the other hand, when the remaining capacity is equal to or less than the second predetermined value, the output from the fuel cell By changing the gas supply amount so as to give priority to the above, the assist of the fuel cell by the power storage device is suppressed.

  Accordingly, since the fuel cell performs low-efficiency power generation with the output voltage adjusted to the warm-up voltage by the voltage adjusting means, the warm-up is performed quickly and the temperature is quickly increased. can do. That is, if low-efficiency power generation is performed, the power loss of the fuel cell increases and the power loss is converted into heat.

  In addition, since the electric power supplied from the fuel cell to the drive motor during the warm-up decreases due to a decrease in the gas supply amount, the share of the fuel cell relative to the required power of the drive motor is relatively And the burden on the power storage device that assists the fuel cell relatively increases.

  Therefore, by increasing the power supplied from the power storage device (by increasing the discharge amount of the power storage device), the power storage device can be warmed up due to discharge.

  In this way, the output voltage is adjusted to the warm-up voltage by the voltage adjusting means, and the fuel cell is quickly warmed up by performing low-efficiency power generation. Warming up can be performed quickly by discharging. Thereby, it is possible to effectively warm up both the fuel cell and the power storage device.

  When the warm-up of the fuel cell and the power storage device is completed, the adjustment of the output voltage to the voltage at the time of warm-up by the voltage adjusting unit is released, and the adjustment of the output voltage during the normal operation is performed. When started, the warm-up control is canceled.

  Thus, according to the present invention, both the fuel cell and the power storage device can be warmed up. Therefore, after the warm-up is completed, the original performance of the fuel cell vehicle is achieved. Can be fully exhibited.

  Further, the control means performs the warm-up control by directly connecting the fuel cell and the power storage device using the voltage adjusting means, and if the warm-up of the fuel cell and the power storage device is completed, It is preferable that the warm-up control is canceled by releasing the direct connection state between the fuel cell and the power storage device and starting the adjustment of the output voltage.

  Thus, the loss generated in the voltage adjusting means can be reduced by bringing the voltage adjusting means into a direct connection state when warming up.

  Further, in the warm-up control, when the remaining capacity decreases below the second predetermined value, the output current of the fuel cell is increased and the output current of the power storage device is increased by increasing the gas supply amount. When the remaining capacity becomes higher than the first predetermined value, the output current of the fuel cell is decreased and the output current of the power storage device is increased by decreasing the gas supply amount. Just do it.

  Therefore, the control means increases the power supplied from the fuel cell and suppresses the assist of the fuel cell by the power storage device when the remaining capacity falls below the second predetermined value. On the other hand, when the remaining capacity becomes higher than the first predetermined value, the power supplied from the fuel cell is decreased, and the assist of the fuel cell by the power storage device is increased. Will be controlled. As a result, the temperature rise performance of the fuel cell and the power storage device can be improved, so that the startup performance of the fuel cell vehicle can be improved.

  Further, it is preferable that the control means prohibits the warm-up control when a required power of a load including the drive motor driven by power supply from the fuel cell is a predetermined value or less. Thereby, when it is not necessary to start the said fuel cell vehicle rapidly, since active warming-up is not performed, wasteful power consumption can be suppressed.

  In the above description, the case has been described in which the output voltage of the fuel cell is stepped down to the output voltage of the power storage device by the voltage adjusting means to establish a direct connection state. That is, if the voltage adjusting means cannot set the output voltage of the fuel cell to be lower than the output voltage of the power storage device, the fuel cell and the power storage device are directly connected, and then the fuel cell And the warming-up is performed for both of the power storage devices.

  The present invention is not limited to this configuration, and if the voltage adjusting means is configured so that the output voltage of the fuel cell can be set lower than the output voltage of the power storage device, the fuel cell When the vehicle is started, both the fuel cell and the power storage device are warmed up while the output voltage of the fuel cell is set lower than the output voltage of the power storage device by the voltage adjusting means. After the warm-up is completed, the low voltage state is canceled and the adjustment of the output voltage of the fuel cell by the voltage adjusting means may be started.

  According to the present invention, both the fuel cell and the power storage device can be warmed up, so that the original performance of the fuel cell vehicle can be fully exhibited after the warming up is completed. it can.

1 is a schematic overall configuration diagram of a fuel cell vehicle according to an embodiment of the present invention. It is a block diagram of the electric power system of the said fuel cell vehicle. It is a schematic block diagram of the fuel cell unit in the said embodiment. It is a figure which shows the detail of the DC / DC converter in the said embodiment. It is a flowchart of basic control in an electronic control unit (ECU). It is a flowchart which calculates a system load. It is a figure which shows the relationship between the present motor rotation speed and motor expected power consumption. It is a figure which shows an example of the relationship between the electric potential of the fuel cell which comprises a fuel cell, and the amount of degradation of a cell. It is a cyclic voltammetry figure which shows the example of the mode of advancing of oxidation, and a progress of reduction | restoration when the fluctuation speeds of the electric potential of a fuel cell differ. It is explanatory drawing of the normal electric current-voltage characteristic of a fuel cell. It is a figure which shows the relationship between a cathode stoichiometric ratio and a cell current. It is a figure which shows the relationship between a cell voltage and the emitted-heat amount of a fuel cell. It is explanatory drawing of the several electric power supply mode in the said embodiment. It is explanatory drawing which shows the relationship between the output of a battery and the output of a fuel cell in battery assist priority control and FC electric power generation priority control. 4 is a flowchart in which the ECU performs energy management of the fuel cell vehicle. It is a flowchart of warm-up mode (mode D control). It is a figure which shows the relationship between target FC electric current and target oxygen concentration. It is a figure which shows the relationship between target oxygen concentration and target FC electric current, target air pump rotation speed, and target water pump rotation speed. It is a figure which shows the relationship between target oxygen concentration, target FC electric current, and target back pressure valve opening. It is a figure which shows the relationship between target FC electric current and an air flow rate. It is a figure which shows the relationship between the opening degree of a circulation valve, and a circulating gas flow rate. It is a flowchart of normal control (mode A control-mode C control). It is a flowchart of torque control of a motor. It is a time chart explaining the time change of the voltage in this embodiment, electric current, electric power, temperature, and SOC. It is a time chart explaining the time change of the voltage in this embodiment, electric current, electric power, SOC, and an air pump rotation speed.

[Configuration of this embodiment]
FIG. 1 is a schematic overall 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. FIG. 2 is a block diagram of the power system of the FC vehicle 10. As shown in FIGS. 1 and 2, the FC vehicle 10 includes a fuel cell system 12 (hereinafter referred to as “FC system 12”), a travel motor 14 (hereinafter referred to as “motor 14”) (drive motor), an inverter, and the like. 16.

  The FC system 12 includes a fuel cell unit 18 (hereinafter referred to as “FC unit 18”), a high voltage battery 20 (hereinafter also referred to as “battery 20”) (power storage device), and a DC / DC converter 22 (voltage adjusting means). ) And an electronic control unit 24 (hereinafter referred to as “ECU 24”) (control means).

  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 or the like (see FIG. 2).

  The inverter 16 is configured as a three-phase bridge type, performs DC / AC conversion, converts DC to three-phase AC and supplies it to the motor 14, and supplies the DC after AC / DC conversion accompanying the regenerative operation. It is supplied to the battery 20 or the like through the DC / DC converter 22.

  The motor 14 and the inverter 16 are collectively referred to as a load 30. The load 30 can also include components such as an air pump 60, a water pump 80, and an air conditioner 90 described later.

  FIG. 3 is a schematic configuration diagram of the FC unit 18. The FC unit 18 includes a fuel cell stack 40 (hereinafter referred to as “FC stack 40” or “FC40”), an anode system 41 that supplies and discharges hydrogen (fuel gas) to and from the anode of the FC stack 40, and the FC stack 40. A cathode system 43 that supplies and discharges oxygen-containing air (oxidant gas) to the cathode, a cooling system 45 that cools the FC stack 40, and a cell voltage monitor 42.

  The FC stack 40 has, for example, a structure in which fuel cell cells (hereinafter referred to as “FC cells”) formed by sandwiching a solid polymer electrolyte membrane from both sides between an anode electrode and a cathode electrode are stacked.

  The anode system 41 includes a hydrogen tank 44, a regulator 46, an ejector 48, and a purge valve 50. The hydrogen tank 44 stores hydrogen as a fuel gas, and is connected to the inlet of the anode flow path 52 through a pipe 44a, a regulator 46, a pipe 46a, an ejector 48, and a pipe 48a. Thereby, the hydrogen in the hydrogen tank 44 can be supplied to the anode flow path 52 via the pipe 44a and the like. Note that a shutoff valve (not shown) is provided in the pipe 44a, and the shutoff valve is opened by the ECU 24 when the FC stack 40 generates power.

  The regulator 46 adjusts the pressure of the introduced hydrogen to a predetermined value and discharges it. That is, the regulator 46 controls the downstream pressure (anode hydrogen pressure) in accordance with the cathode pressure (pilot pressure) input via the pipe 46b. Accordingly, the pressure of hydrogen on the anode side is linked to the pressure of air on the cathode side. As will be described later, when the rotational speed of the air pump 60 (gas supply means) is changed to change the oxygen concentration, the anode side hydrogen pressure is changed. Hydrogen pressure also changes.

  The ejector 48 generates a negative pressure by injecting hydrogen from the hydrogen tank 44 with a nozzle, and sucks the anode off gas of the pipe 48b by this negative pressure.

  The outlet of the anode flow path 52 is connected to the intake port of the ejector 48 through the pipe 48b. Then, the anode off-gas (hydrogen) circulated by the anode off-gas discharged from the anode channel 52 being introduced again into the ejector 48 through the pipe 48b.

  The anode off gas contains hydrogen and water vapor that were not consumed by the electrode reaction at the anode. The pipe 48b is provided with a gas-liquid separator (not shown) that separates and collects moisture {condensed water (liquid), water vapor (gas)} contained in the anode off gas.

  A part of the pipe 48b is connected to a dilution box 54 provided in a pipe 64b described later via a pipe 50a, a purge valve 50, and a pipe 50b. When it is determined that the power generation of the FC stack 40 is not stable, the purge valve 50 is opened for a predetermined time based on a command from the ECU 24. The dilution box 54 dilutes the hydrogen in the anode off gas from the purge valve 50 with the cathode off gas.

  The cathode system 43 includes an air pump 60, a humidifier 62, a back pressure valve 64, a circulation valve 66, flow rate sensors 68 and 70, and a temperature sensor 72.

  The air pump 60 compresses the outside air (air) and sends it to the cathode side, and the intake port thereof communicates with the outside of the vehicle (outside) via a pipe 60a. The discharge port of the air pump 60 is connected to the inlet of the cathode channel 74 through the pipe 60b, the humidifier 62, and the pipe 62a. When the air pump 60 operates in accordance with a command from the ECU 24, the air pump 60 sucks and compresses air outside the vehicle via the pipe 60a, and the compressed air is pumped to the cathode channel 74 through the pipe 60b and the like.

  The humidifier 62 includes a plurality of hollow fiber membranes 62e having moisture permeability. The humidifier 62 exchanges moisture between the air toward the cathode channel 74 and the humid cathode offgas discharged from the cathode channel 74 via the hollow fiber membrane 62e, and the air toward the cathode channel 74 Humidify.

  On the outlet side of the cathode channel 74, a pipe 62b, a humidifier 62, a pipe 64a, a back pressure valve 64, and a pipe 64b are arranged. The cathode off gas (oxidant off gas) discharged from the cathode channel 74 is discharged outside the vehicle through the pipe 62b and the like.

  The back pressure valve 64 is configured by, for example, a butterfly valve, and the air pressure in the cathode channel 74 is controlled by controlling the opening degree of the back pressure valve 64 by the ECU 24. More specifically, when the opening degree of the back pressure valve 64 is reduced, the air pressure in the cathode flow path 74 is increased, and the oxygen concentration (volume concentration) per volume flow rate is increased. On the contrary, when the opening degree of the back pressure valve 64 increases, the pressure of the air in the cathode flow path 74 decreases, and the oxygen concentration (volume concentration) per volume flow rate decreases.

  The pipe 64b is connected to the pipe 60a on the upstream side of the air pump 60 through the pipe 66a, the circulation valve 66, and the pipe 66b. As a result, a part of the exhaust gas (cathode off-gas) is supplied as circulation gas to the pipe 60a through the pipe 66a, the circulation valve 66, and the pipe 66b, merges with new air from the outside of the vehicle, and is taken into the air pump 60. Is done.

  The circulation valve 66 is constituted by, for example, a butterfly valve, and the flow rate of the circulation gas is controlled by the opening degree of the circulation valve 66 being controlled by the ECU 24.

  The flow rate sensor 68 is attached to the pipe 60b, detects the flow rate [g / s] of the air flowing toward the cathode flow path 74, and outputs it to the ECU 24. The flow rate sensor 70 is attached to the pipe 66b, detects the flow rate Qc [g / s] of the circulating gas toward the pipe 60a, and outputs it to the ECU 24.

  The temperature sensor 72 is attached to the pipe 64a, detects the temperature of the cathode off gas, and outputs it to the ECU 24. Here, since the temperature of the circulating gas is substantially equal to the temperature of the cathode off gas, the temperature of the circulating gas can be detected based on the temperature of the cathode off gas detected by the temperature sensor 72.

  The cooling system 45 includes a water pump 80, a radiator 82, a radiator fan 84, a temperature sensor 86, and the like. The water pump 80 cools the FC stack 40 by circulating cooling water (refrigerant) in the FC stack 40. The cooling water whose temperature has risen by cooling the FC stack 40 is radiated by the radiator 82 that receives the air blown by the radiator fan 84. The temperature sensor 86 detects the temperature of the cooling water (hereinafter referred to as “water temperature Tw”) and outputs it to the ECU 24.

  The cell voltage monitor 42 is a device that detects a cell voltage Vcell for each of a plurality of single cells constituting the FC stack 40, and includes a monitor main body and a wire harness that connects the monitor main body and each single cell. The monitor main body scans all the single cells at a predetermined period, detects the cell voltage Vcell of each single cell, and calculates the average cell voltage and the lowest cell voltage. Then, the average cell voltage and the lowest cell voltage are output to the ECU 24.

  As shown in FIG. 2, the power from the FC stack 40 (hereinafter referred to as “FC power Pfc”) includes the inverter 16 and the motor 14 (during power running), the DC / DC converter 22 and the high-voltage battery 20 (during charging). In addition, the air pump 60, the water pump 80, the air conditioner 90, the downverter 92 (step-down DC-DC converter), the low voltage battery 94, the accessory 96, the ECU 24, and the radiator fan 84 are supplied. As shown in FIG. 1, a backflow prevention diode 98 is disposed between the FC unit 18 (FC stack 40), the inverter 16, and the DC / DC converter 22. In addition, the power generation voltage of the FC stack 40 (hereinafter referred to as “FC voltage Vfc”) is detected by the voltage sensor 100 (see FIG. 4), and the power generation current of the FC stack 40 (hereinafter referred to as “FC current Ifc”). Both are detected by the current sensor 102 and output to the ECU 24.

  The battery 20 is a power storage device (energy storage) including a plurality of battery cells, and for example, a lithium ion secondary battery, a nickel hydride secondary battery, or a capacitor 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 104 (see FIG. 2), and the output current of the battery 20 (hereinafter referred to as “battery current Ibat”) [A]. Is detected by the current sensor 106, the remaining capacity of the battery 20 (hereinafter referred to as “SOC”) [%] is detected by the SOC sensor 108, and the temperature of the battery 20 (hereinafter referred to as “battery temperature Tbat”). Are detected by the temperature sensor 109 and output to the ECU 24, respectively. Note that the ECU 24 can calculate the SOC [%] based on the battery voltage Vbat and the battery current Ibat. In this case, the SOC sensor 108 may be omitted.

  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. Are controlled under the control of the ECU 24.

  FIG. 4 shows details of the DC / DC converter 22 in this embodiment. As shown in FIG. 4, 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 the connection point between the load 30 and the FC stack 40. Yes.

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

  As shown in FIG. 4, the DC / DC converter 22 includes a phase arm UA disposed between the primary side 1S and the secondary side 2S, and a reactor 110.

  The phase arm UA includes an upper arm element (upper arm switching element 112 and antiparallel diode 114) and a lower arm element (lower arm switching element 116 and antiparallel diode 118). As the upper arm switching element 112 and the lower arm switching element 116, for example, a MOSFET or an IGBT is employed.

  Reactor 110 is inserted between the middle point (common connection point) of phase arm UA and the positive electrode of battery 20, and converts voltage between primary voltage V <b> 1 and secondary voltage V <b> 2 by DC / DC converter 22. In particular, it has the function of storing and releasing energy.

  The upper arm switching element 112 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 116 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 the voltage sensor 120 provided in parallel with the primary-side smoothing capacitor 122, and detects the primary-side current (primary current I1) [A] with the current sensor 124. To do. Further, the ECU 24 detects the secondary voltage V2 by the voltage sensor 126 provided in parallel with the secondary-side smoothing capacitor 128, and detects the secondary-side current (secondary current I2) [A] by the current sensor 130. To do.

  At the time of boosting of the DC / DC converter 22, at the first timing, the gate drive signal UL is set to the high level and the gate drive signal UH is set to the low level, and energy is accumulated from the battery 20 in the reactor 110 (the positive side of the battery 20). Current path from the reactor 110 to the reactor 110, the lower arm switching element 116, and the negative side of the battery 20). At the second timing, the gate drive signal UL is set to the low level and the gate drive signal UH is set to the low level, and the energy stored in the reactor 110 is supplied to the secondary side 2S through the diode 114 (from the positive side of the battery 20). Reactor 110, diode 114, positive side of secondary side 2S, load 30, etc., negative side of secondary side 2S, and negative side current path of battery 20). Thereafter, the first timing and the second timing at the time of boosting are repeated.

  At the time of step-down of the DC / DC converter 22, at the first timing, the gate drive signal UH is set to the high level and the gate drive signal UL is set to the low level, and the secondary side 2S (the FC stack 40 or the motor 14 is being regenerated) in the reactor 110. Energy is stored and the battery 20 is charged. At the second timing, the gate drive signal UH is set to the low level and the gate drive signal UL is set to the low level, the energy accumulated in the reactor 110 is supplied to the battery 20 through the diode 118 and the reactor 110, and the battery 20 is charged. . As can be seen from FIG. 2, the regenerative power can be supplied to auxiliary equipment such as the air pump 60. Thereafter, the first timing and the second timing at the time of step-down are repeated.

  The DC / DC converter 22 can operate not only as the above-described chopper type but also as a direct connection type. When operating as a direct connection type, the gate drive signal UH is set to the high level and the gate drive signal UL is set to the low level, and when the battery 20 is discharged, the primary side 1S is changed to the secondary side 2S through the diode 114. When current is supplied (for example, power is supplied from the battery 20 to the load 30) and the battery 20 is charged, current is supplied to the battery 20 from the secondary side 2S through the upper arm switching element 112 (for example, The regenerative power is supplied from the motor 14 to the battery 20).

  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 140 (see FIGS. 1 and 2). In the control, a program stored in a memory (ROM) is executed, and the cell voltage monitor 42, flow sensors 68 and 70, temperature sensors 72, 86 and 109, voltage sensors 100, 104, 120 and 126, current Detection values of various sensors such as the sensors 102, 106, 124, and 130 and the SOC sensor 108 are used.

  The various sensors here include an opening sensor 150, a motor rotation number sensor 152, and an outside air temperature sensor 154 (see FIG. 1) in addition to the above sensors. The opening sensor 150 detects the opening θp [degree] of the accelerator pedal 156. The motor rotation speed sensor 152 detects the rotation speed Nm [rpm] of the motor 14. The ECU 24 detects the vehicle speed V [km / h] of the FC vehicle 10 using the rotational speed Nm. The outside air temperature sensor 154 detects the outside air temperature of the vehicle 10 (hereinafter referred to as “outside air temperature Tex”). Further, a main switch 158 (hereinafter referred to as “main SW 158”) is connected to the ECU 24. The main SW 158 switches whether or not power can be supplied from the FC unit 18 and the battery 20 to the motor 14, and is a switch that can be operated by the user (a switch corresponding to an ignition switch of the engine vehicle).

  The ECU 24 includes a microcomputer and has an input / output interface 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 determines the load required for the FC system 12 as a whole of the FC vehicle 10 determined based on the input (load request) from various switches and various sensors in addition to the state of the FC stack 40, the state of the battery 20, and the state of the motor 14. Therefore, the distribution (sharing) of the load to be borne by the FC stack 40, the load to be borne by the battery 20 and the load to be borne by the regenerative power source (motor 14) is determined while arbitrating, and the motor 14 and inverter 16 , Sends a command to the FC unit 18, the battery 20 and the DC / DC converter 22.

[Description of basic control operation of this embodiment]
Next, control in the ECU 24 will be described.

  FIG. 5 shows a flowchart of basic control in the ECU 24. In step S1, the ECU 24 determines whether or not the main SW 158 (see FIG. 1) is on. If the main SW 158 is not on (S1: NO), step S1 is repeated. If the main SW 158 is on (S1: YES), the process proceeds to step S2. In step S2, the ECU 24 calculates a load (system load Psys) [W] required for the FC system 12.

  In step S3, the ECU 24 performs energy management of the FC system 12. The energy management here is mainly a process of calculating the power generation amount (FC power Pfc) of the FC stack 40 and the output of the battery 20 (battery power Pbat), and while suppressing the deterioration of the FC stack 40, the FC system 12 It is intended to improve the overall output efficiency. In step S3, the ECU 24 also performs energy management in a warm-up mode (mode D control, warm-up control) in a direct connection state between an FC stack 40 and a battery 20 described later.

  In step S4, the ECU 24 controls peripheral devices of the FC stack 40, that is, the air pump 60, the back pressure valve 64, the circulation valve 66, and the water pump 80 (FC power generation control). In step S <b> 5, the ECU 24 performs torque control of the motor 14.

  In step S6, the ECU 24 determines whether or not the main SW 158 is off. If the main SW 158 is not off (S6: NO), the process returns to step S2. If the main SW 158 is off (S6: YES), the current process is terminated.

[Calculation of system load]
FIG. 6 shows a flowchart in which the ECU 24 calculates the system load Psys. In step S11, the ECU 24 reads the opening degree θp of the accelerator pedal 156 from the opening degree sensor 150 (see FIG. 1). In step S12, the ECU 24 reads the rotational speed Nm of the motor 14 from the motor rotational speed sensor 152.

  In step S13, the ECU 24 calculates the expected power consumption Pm [W] of the motor 14 based on the opening degree θp and the rotational speed Nm. Specifically, in the map shown in FIG. 7, the relationship between the rotational speed Nm and the predicted power consumption Pm is stored for each opening θp. For example, the characteristic 160 is used when the opening degree θp is θp1. Similarly, when the opening degree θp is θp2, θp3, θp4, θp5, and θp6, the characteristics 162, 164, 166, 168, and 170 are used, respectively. And after specifying the characteristic which shows the relationship between the rotation speed Nm and estimated power consumption Pm based on opening degree (theta) p, the expected power consumption Pm according to rotation speed Nm is specified.

  In step S14, the ECU 24 reads the current operation status from each auxiliary machine. Examples of the auxiliary machine include a high-voltage auxiliary machine including an air pump 60, a water pump 80, and an air conditioner 90, and a low-voltage electric machine including a low-voltage battery 94, an accessory 96, the ECU 24, and a radiator fan 84. Auxiliary equipment is included. For example, in the case of the air pump 60 and the water pump 80, the rotation speed Nap and Nwp [rpm] are read. If it is the air conditioner 90, the output setting is read.

  In step S15, the ECU 24 calculates the power consumption Pa [W] of the auxiliary machine according to the current operation status of each auxiliary machine. In step S16, the ECU 24 calculates the sum of the predicted power consumption Pm of the motor 14 and the power consumption Pa of the auxiliary machine as the predicted power consumption of the FC vehicle 10 as a whole (that is, the system load Psys).

  As described above, in the energy management in this embodiment, it is intended to improve the output of the entire FC system 12 while suppressing the deterioration of the FC stack 40.

  FIG. 8 shows an example of the relationship between the potential (cell voltage Vcell) [V] of the FC cells constituting the FC stack 40 and the amount of cell degradation D. That is, the curve 180 in FIG. 8 shows the relationship between the cell voltage Vcell and the deterioration amount D.

  In FIG. 8, in a region below potential v1 (for example, 0.5 V) (hereinafter referred to as “platinum aggregation increasing region R1” or “aggregation increasing region R1”), a reduction reaction is performed on platinum (platinum oxide) contained in the FC cell. Proceeds violently and platinum aggregates excessively. The potential v1 to the potential v2 (for example, 0.8 V) is a region where the reduction reaction proceeds stably (hereinafter referred to as “platinum reduction region R2” or “reduction region R2”).

  The potential v2 to the potential v3 (for example, 0.9 V) is a region where the redox reaction proceeds with respect to platinum (hereinafter referred to as “platinum redox progress region R3” or “redox region R3”). The potential v3 to the potential v4 (for example, 0.95 V) is a region where the oxidation reaction of platinum proceeds stably (hereinafter referred to as “platinum oxidation stable region R4” or “oxidation region R4”). The potential v4 to OCV (open circuit voltage) is a region where the oxidation of carbon contained in the cell proceeds (hereinafter referred to as “carbon oxidation region R5”).

  As described above, in FIG. 8, if the cell voltage Vcell is in the platinum reduction region R2 or the platinum oxidation stable region R4, the progress of deterioration of the FC cell is small compared to the adjacent regions. On the other hand, when the cell voltage Vcell is in the platinum aggregation increasing region R1, the platinum oxidation-reduction progress region R3, or the carbon oxidation region R5, the progress of deterioration of the FC cell is larger than that of the adjacent region.

  In FIG. 8, the curve 180 is uniquely defined, but in actuality, the curve 180 changes according to the amount of fluctuation (fluctuation speed Acell) [V / sec] of the cell voltage Vcell per unit time. .

  FIG. 9 is a cyclic voltammetry diagram showing an example of the state of the progress of oxidation and the progress of reduction when the fluctuation rates Acell are different. In FIG. 9, a curve 190 indicates a case where the fluctuation speed Acell is high, and a curve 192 indicates a case where the fluctuation speed Acell is low. As can be seen from FIG. 9, since the degree of progress of oxidation or reduction differs depending on the fluctuation speed Acell, the potentials v1 to v4 are not necessarily uniquely specified. In addition, the potentials v1 to v4 can change depending on individual differences of FC cells. For this reason, it is preferable to set the potentials v1 to v4 as those in which an error is reflected in the theoretical value, the simulation value, or the actual measurement value.

  Further, the current-voltage (IV) characteristic of the FC cell is similar to that of a general fuel battery cell, and is an IV characteristic 200 (also referred to as a normal IV characteristic 200) shown as “normal” in FIG. As shown, the cell current Icell [A] increases as the cell voltage Vcell decreases. In addition, the power generation voltage (FC voltage Vfc) of the FC stack 40 is obtained by multiplying the cell voltage Vcell by the number of serial connections Nfc in the FC stack 40 (Vfc = Vcell × Nfc). The serial connection number Nfc is the number of FC cells connected in series in the FC stack 40, and is also simply referred to as “cell number” hereinafter.

  Based on the above, in this embodiment, the ECU 24 is connected to the FC unit 18 and the DC / DC converter so that the cell voltage Vcell (according to the FC voltage Vfc) falls within the platinum reduction region R2 or the platinum oxidation stable region R4. 22 is controlled to prevent the FC stack 40 from deteriorating due to the FC voltage Vfc being in the regions R1, R3, and R5 (particularly, the platinum oxidation-reduction progress region R3).

  Specifically, in this embodiment, when the DC / DC converter 22 is performing a voltage conversion operation, the target voltage (target FC voltage Vfctgt) [V] of the FC stack 40 is mainly set in the platinum reduction region R2. While setting, it is set in the platinum oxidation stable region R4 as necessary. By switching the target FC voltage Vfctgt in this way, the time during which the FC voltage Vfc is within the regions R1, R3, R5 (particularly, the platinum oxidation-reduction progress region R3) is shortened as much as possible, and the FC stack 40 is deteriorated. Can be prevented.

  In the above processing, there is a case where the power supplied to the FC stack 40 (FC power Pfc) and the system load Psys are not equal. In this regard, when the FC power Pfc is below the system load Psys, the shortage is supplied from the battery 20. Further, when the FC power Pfc exceeds the system load Psys, the excess is charged in the battery 20.

  Further, although the potentials v1 to v4 are specified as specific numerical values in FIG. 8, this is for performing the control described later, and the numerical values are determined taking into account the convenience of control. In other words, as can be seen from the curve 180, the deterioration amount D changes continuously, so that the potentials v1 to v4 can be appropriately set according to the control specifications.

  However, the platinum reduction region R2 includes the minimum value of the curve 180 (first minimum value Vlmi1). The platinum redox progression region R3 includes the maximum value (maximum value Vlmx) of the curve 180. The platinum oxidation stable region R4 includes another minimum value (second minimum value Vlmi2) of the curve 180.

  Further, as shown in FIG. 11, the normal IV characteristic 200 of FIG. 10 is in a state where the cathode stoichiometric ratio (≈oxygen concentration Co) is rich in oxygen that is equal to or higher than the normal stoichiometric ratio (normal stoichiometric ratio). It is a characteristic sometimes obtained. In other words, the oxygen concentration Co is set to an oxygen concentration higher than the normal oxygen concentration. The cathode stoichiometric ratio is expressed by (cathode stoichiometric ratio) = (air flow rate supplied to the cathode electrode) / (air flow rate consumed by power generation). In this embodiment, the cathode stoichiometric ratio is also simply referred to as the stoichiometric ratio.

  In addition, the oxygen-rich state means that the cell current (current output from a single cell) Icell is substantially constant even when the cathode stoichiometric ratio (≈oxygen concentration Co) is increased, and is higher than the normal stoichiometric ratio where the cell becomes saturated. Means oxygen in the region.

  The same applies to hydrogen. That is, the anode stoichiometric ratio (≈hydrogen concentration) is represented by (anode stoichiometric ratio) = (hydrogen flow rate supplied to the anode electrode) / (hydrogen flow rate consumed by power generation).

  FIG. 12 is a diagram showing the relationship between the cell voltage Vcell and the heat dissipation amount Hfc [kW] of the FC stack 40 (unit cell). As shown in FIG. 12, the heat dissipation amount Hfc of the FC stack 40 depends on the cell voltage Vcell and does not depend on the cell current Icell. Therefore, in the warm-up mode (mode D control) to be described later, if the FC voltage Vfc is constant, the heat dissipation amount Hfc can be maintained constant, while the FC voltage Vfc is reduced due to the direct connection state. Thus, the heat dissipation amount Hfc can be increased. That is, when low-efficiency power generation is performed in the FC stack 40 by reducing the FC voltage Vfc to the battery voltage Vbat and bringing the FC stack 40 and the battery 20 into a direct connection state, a normal control mode (mode described later) Compared to the case of (A control to mode C control), the power loss in the FC stack 40 increases, the heat release amount Hfc increases, and warming up can be performed quickly.

[Power supply control and power supply mode used in energy management]
FIG. 13 is an explanatory diagram of a plurality of power supply modes in this embodiment. In this embodiment, the following control method (power supply mode) is used as a power supply control method (power supply mode) used by the ECU 24 in energy management.

  That is, in this embodiment, the electric power used by the ECU 24 in energy management in order to supply electric power while keeping the FC voltage Vfc (according to the cell voltage Vcell) in the platinum reduction region R2 or the platinum oxidation stable region R4. The supply mode (operation mode) is switched to the normal control mode or the warm-up mode.

  The normal control mode is a mode used during normal operation of the FC vehicle 10 that is not the warm-up mode. That is, in the normal control mode, (1) mode A control (voltage) applied to a relatively high target FC power Pfctgt according to a target value of FC voltage (target FC power Pfctgt) based on the system load Psys. (Variable / current variable control mode), (2) Mode B control (one voltage applied) when the FC stack 40 may be exposed to a high voltage because the target FC power Pfctgt is relatively medium. (Fixed / current variable control mode), (3) Mode C control applied when the FC stack 40 may be exposed to a high voltage because the target FC power Pfctgt is relatively small (the other fixed voltage / There are three control modes: current variable control mode. Accordingly, in the normal control mode, the ECU 24 controls the power supply by switching to an appropriate mode according to the target FC power Pfctgt.

  On the other hand, in the warm-up mode, when the FC vehicle 10 is started at a low temperature such as below freezing point, the FC voltage Vfc is stepped down by the DC / DC converter 22 and the FC stack 40 and the battery 20 are directly connected (Vfc≈Vbat). ), A power supply mode (mode D control) for warming up both the FC stack 40 and the battery 20 by performing voltage fixing / current variable control similar to mode B control and mode C control. ). That is, in the warm-up mode, warm-up is performed on both the FC stack 40 and the battery 20 with the FC voltage Vfc set to a voltage lower than the output voltage during normal operation (voltage during warm-up).

  In FIG. 13, for example, mode A control, mode B control, and mode D control are performed in the platinum reduction region R2 having the potential v2 or lower, and mode C control is performed in the platinum oxidation stable region R4 having the potential v3 or higher. Thus, the cell voltage Vcell corresponding to the FC voltage Vfc is prevented from entering the platinum redox progression region R3 of v2 to v3. Of course, mode A control to mode D control may be performed in the platinum reduction region R2, or mode A control to mode D control may be performed in the platinum oxidation stable region R4.

  Further, in FIG. 13, since the FC voltage Vfc is higher than the battery voltage Vbat in the normal control mode, the DC / DC converter 22 steps down the FC voltage Vfc to the battery voltage Vbat (warm-up voltage) to establish a direct connection state. Thus, the case of shifting to the mode D control is illustrated. That is, in this embodiment, since the DC / DC converter 22 is configured such that the FC voltage Vfc cannot be set lower than the battery voltage Vbat, the FC stack 40 and the battery 20 are directly connected to each other. The mode D control can be performed.

  However, this embodiment is not limited to the above description. If the DC / DC converter 22 is configured so that the FC voltage Vfc can be set lower than the battery voltage Vbat, the DC / DC It is also possible to perform the mode D control with the converter 22 setting the FC voltage Vfc to a voltage lower than the battery voltage Vbat (the voltage during warm-up).

  Here, the above-described mode A control to mode D control will be described in more detail.

  In the mode A control, the FC current Ifc is controlled by adjusting the target FC voltage Vfctgt in a state in which the target value (target oxygen concentration Cotgt) of the oxygen concentration Co is maintained normally (including a state where oxygen is rich). . That is, as shown in FIG. 13, in the mode A control executed when the target FC power Pfctgt is equal to or higher than the threshold power Pthp, the normal IV characteristic 200 of the FC stack 40 (the same as the normal IV characteristic 200 shown in FIG. 10). Characteristic) and the FC voltage Vfc and the FC current Ifc are changed (controlled) on the IV characteristic 200.

  Specifically, in the mode A control, the ECU 24 first calculates a target value (target FC current Ifctgt) of the FC current Ifc according to a target value (target FC power Pfctgt) of the FC power Pfc based on the system load Psys. Next, the ECU 24 calculates a target FC voltage Vfctgt corresponding to the target FC current Ifctgt. Then, the ECU 24 controls the DC / DC converter 22 so that the FC voltage Vfc becomes the target FC voltage Vfctgt. That is, in the mode A control, the ECU 24 controls the FC voltage Vfc to increase the FC current Ifc by boosting the primary voltage V1 by the DC / DC converter 22 so that the secondary voltage V2 becomes the target FC voltage Vfctgt. Control.

  Therefore, according to the mode A control, even if the target FC power Pfctgt is a high load equal to or higher than the threshold power Pthp, the DC / DC converter 22 responds to the target FC power Pfctgt so as to follow the normal IV characteristic 200. Thus, the secondary voltage V2 (FC voltage Vfc) can be changed. In this case, basically, the system load Psys is covered by the FC power Pfc.

  As shown in FIG. 13, the mode A control is executed within a range between the potential v2 at which the mode B control is executed and the potential at which the mode D control is executed on the normal IV characteristic 200. Normal control mode (variable voltage / variable current control mode).

  In the mode B control, the target cell voltage Vcelltgt (= target FC voltage Vfctgt / number of cells Nfc) is set to a reference voltage that is lower than the voltage lower than the oxidation-reduction progress region R3 {in this embodiment, the voltage v2 (= 0. 8V)} and the target oxygen concentration Cotgt is made variable to make the FC current Ifc variable. That is, as shown in FIG. 13, in the mode B control, the target oxygen concentration Cotgt is reduced by keeping the cell voltage Vcell constant (Vcell = v2) within the range of the threshold powers Pthq to Pthp. Reduce the concentration Co.

  As shown in FIG. 11, when the cathode stoichiometric ratio (≈oxygen concentration Co) decreases, the cell current Icell (FC current Ifc) also decreases. Further, the FC stack 40 deteriorates as the time for which it is exposed to a high potential state becomes longer. Therefore, in the mode B control, the cell current Icell (FC current Ifc) and the FC power Pfc are changed by increasing / decreasing the target oxygen concentration Cotgt while keeping the cell voltage Vcell constant (Vcell = v2 = 0.8V). It is possible to suppress the deterioration of the FC stack 40 by controlling.

  In the mode C control, the target cell voltage Vcelltgt is fixed to a voltage outside the redox progression region R3 (in this embodiment, the voltage v3 (= 0.9 V)), and the FC current Ifc is variable. Also in the mode C control, similarly to the mode B control, the oxygen concentration Co is lowered by lowering the target oxygen concentration Cotgt while keeping the cell voltage Vcell constant (Vcell = v3). As described above, when the cathode stoichiometric ratio decreases, the cell current Icell also decreases. Therefore, if the target oxygen concentration Cotgt is increased or decreased while the cell voltage Vcell is kept constant (Vcell = v3 = 0.9 V), the cell current Icell is increased or decreased. In addition, the FC power Pfc is controlled, and the deterioration of the FC stack 40 can be suppressed.

  In the above-described normal control mode (mode A control to mode C control), when the FC power Pfc is reduced relative to the system load Psys due to the decrease in the FC power Pfc due to the decrease in the cell current Icell. The shortage of the FC power Pfc may be assisted from the battery 20. Further, when the FC power Pfc is larger than the system load Psys, the battery 20 may be charged with a surplus of the FC power Pfc.

  In the mode D control, when the FC vehicle 10 is started at a low temperature such as below freezing point, the DC / DC converter 22 is operated as a direct connection type, that is, the voltage conversion operation in the DC / DC converter 22 is stopped and the FC stack 40 is operated. In the state in which the battery 20 is directly connected (Vfc≈Vbat) and then the FC voltage Vfc and the battery voltage Vbat are maintained at substantially the same voltage value, the target cell is operated as in the above-described mode B control and mode C control. The voltage Vcelltgt is fixed to a voltage outside the redox progression region R3 (in this embodiment, a voltage within the platinum reduction region R2 equal to or lower than the voltage v2 (= 0.8 V)), and the target FC current Ifctgt (FC power Pfc). The target oxygen concentration Cotgt is variable.

  That is, in the mode D control, the voltage conversion operation of the DC / DC converter 22 is stopped after the FC voltage Vfc is reduced to the battery voltage Vbat and the FC stack 40 and the battery 20 are directly connected ( Since the FC voltage Vfc is not controlled), the target FC voltage Vfctgt is actually Vfctgt = Vfc≈Vbat. Further, if the target oxygen concentration Cotgt is increased or decreased while the cell voltage Vcell is kept constant, the cell current Icell changes. As a result, as shown in FIG. 13, when the target FC voltage Ifctgt is changed while the target FC voltage Vfctgt is fixed, the target oxygen concentration Cotgt increases and decreases as shown in FIG. 11, and the target oxygen concentration Cotgt increases and decreases. Accordingly, the FC current Ifc also changes. Therefore, in the mode D control, the target cell voltage Vcelltgt (= target FC voltage Vfctgt / number of cells Nfc) cannot be controlled to a desired voltage value, but by making the target oxygen concentration Cotgt basically variable, The current Ifc is changed.

  As described above, in the mode D control, the FC voltage Vfc is lowered to the battery voltage Vbat to establish a direct connection state, and the oxygen concentration Co is changed. As a result, the power loss increased in the FC stack 40 is converted into heat, and the FC stack 40 can be warmed up due to an increase in internal temperature caused by this heat.

  Further, in the FC stack 40, compared with the same voltage in the normal control mode, the FC power Pfc supplied to the load 30 is reduced, and the share of power with respect to the system load Psys can be relatively reduced.

  That is, as shown in FIG. 14, when the FC power Pfc is the minimum output value (minimum power) Pfc_min with respect to the system load Psys, the power (system load Psys) required from the load 30 and the minimum power A difference (battery power Pbat = Psys−Pfc_min) from Pfc_min may be output from the battery 20. In this way, the battery 20 can be warmed up due to power supply (discharge) from the battery 20 to the load 30. In the mode D control, the control in which the battery 20 preferentially supplies the battery power Pbat to the load 30 so as to assist the power supply from the FC stack 40 is hereinafter referred to as battery assist priority control.

On the other hand, when the SOC of the battery 20 decreases and the battery power Pbat cannot be supplied from the battery 20 to the load 30, the target FC current Ifctgt is set high.
The target oxygen concentration Cotgt may be increased. As a result, the oxygen concentration Co increases and the cell current Icell increases, so that the FC power Pfc equal to or higher than the system load Psys required by the load 30 can be output from the FC stack 40 as shown in FIG. In this case, the battery 20 is charged with surplus power from the FC stack 40. As a result, the battery 20 can be warmed up due to power supply (charging) from the FC stack 40. In the mode D control, the control for supplying the power to the load 30 with the FC power Pfc is hereinafter referred to as FC power generation priority control.

  In FIG. 14, even if the system load Psys is 0, the FC stack 40 does not depend on the SOC, battery assist priority control, or FC power generation priority control until the warm-up is completed. Is output.

  Thus, in the warm-up mode (mode D control, warm-up control), it is possible to perform warm-up for both the FC stack 40 and the battery 20 while taking a balance of the remaining capacity (SOC) of the battery 20. In the mode D control, the ECU 24 actually determines whether to execute the FC power generation priority control or the battery assist priority control based on the SOC [%] value. After setting an appropriate target FC current Ifctgt according to the target FC concentration Ifctgt, the target oxygen concentration Cotgt based on the target FC current Ifctgt is determined, and the oxygen concentration Co is adjusted according to the determined target oxygen concentration Cogtt, thereby changing the FC current Ifc. . That is, switching to either FC power generation priority control or battery assist priority control is performed according to the value of the target FC current Ifctgt. Further, the battery current Ibat can be changed in accordance with the change in the FC current Ifc.

[Energy management flow]
FIG. 15 is a flowchart for the ECU 24 to perform energy management of the FC system 12 (S3 in FIG. 5). In this flowchart, depending on whether the battery 20 and the FC stack 40 need to be warmed up, the normal control mode (mode A control to mode C control) described above or the warm-up mode {mode D control (battery assist priority control, FC power generation priority control)} is executed.

  In step S21 in FIG. 15, the ECU 24 determines whether or not the power required from the load 30 (step S2 in FIG. 5 and the system load Psys calculated in the flowchart in FIG. 6) is equal to or less than a predetermined value. Specifically, the ECU 24 determines whether or not the system load Psys is equal to or less than a system load limit value Psyslmt as a predetermined value.

  When the system load Psys is not equal to or less than the system load limit value Psyslmt (S21: NO), the ECU 24 warms up the FC unit 18 by directly connecting the FC unit 18 (FC stack 40) and the battery 20 in the next step S22. Determine whether it is necessary to do this.

  Specifically, regarding the necessity of warming up of the FC unit 18, the water temperature Tw from the temperature sensor 86 is a threshold value for determining the necessity of warming up (hereinafter referred to as "warmup determination threshold value THTw" or "threshold value THTw"). It is determined by whether or not Alternatively, the necessity of warming up the FC unit 18 may be determined based on whether or not the outside air temperature Tex is equal to or lower than a predetermined threshold value THTex. The threshold values THTw and THTex can be selected from any value from 0 to 10 ° C., for example.

  When it is determined that the FC unit 18 needs to be warmed up (S22: YES), the ECU 24 also adds the FC unit 18 and the battery 20 to the battery 20 when the FC unit 18 and the battery 20 are directly connected in the next step S23. To determine whether it is necessary to warm up.

  Specifically, regarding the necessity of warming-up of the battery 20, the battery temperature Tbat from the temperature sensor 109 is a threshold for determining the necessity of warming up (hereinafter referred to as “warm-up determination threshold THTbat” or “threshold THTbat”). It is determined by whether or not Alternatively, whether or not the battery 20 needs to be warmed up may be determined based on whether or not the outside air temperature Tex is equal to or lower than the threshold value THTex. The threshold value THTbat can be selected from any value from 0 to 10 ° C., for example, similarly to the threshold values THTw and THTex.

  When it is determined that the battery 20 needs to be warmed up (S23: YES), in the next step S24, the ECU 24 determines whether or not the SOC [%] has reached a predetermined value. In this case, as the predetermined value, a battery assist priority threshold (first predetermined value) for determining whether or not to execute battery assist priority control and whether or not to execute FC power generation priority control are determined. The two threshold values of the FC power generation priority threshold (second predetermined value) are set. The ECU 24 determines whether or not the SOC [%] has increased (reached) to the battery assist priority threshold, or whether or not the SOC [%] has decreased (has reached) to the FC power generation priority threshold. judge. These two threshold values are set to different values by providing hysteresis.

  In step S24, when the SOC [%] increases to the battery assist priority threshold value (S24: YES), the ECU 24 determines to execute the battery assist priority control. In the next step S25, the ECU 24 controls the DC / DC converter 22 to directly connect the FC stack 40 and the battery 20, and then the power shortage of the FC power Pfc with respect to the system load Psys {eg, FC power Pfc Is the minimum power Pfc_min, the battery power Pbat} of (Psys−Pfc_min) is output from the battery 20 (battery assist priority control).

  On the other hand, in step S24, when the SOC [%] has decreased to the FC power generation priority threshold (S24: NO), the ECU 24 determines to execute FC power generation priority control. In the next step S26, the ECU 24 controls the DC / DC converter 22 to directly connect the FC stack 40 and the battery 20, and then sets the target FC current Ifctgt high to increase the target oxygen concentration Cotgt. As a result, the oxygen concentration Co increases, the cell current Icell increases, the FC power Pfc supplied from the FC stack 40 to the load 30 increases, and the system load Psys can be covered by the FC power Pfc (FC power generation). Priority control).

  Note that if there is a surplus (Psys-Pfc) in the power supplied from the FC stack 40 to the load 30, the surplus power is charged in the battery 20. Warm-up due to charging from is performed.

  Further, the processes of steps S25 and S26 are not performed at the same time, and the ECU 24 switches to an appropriate mode D control (battery assist priority control or FC power generation priority control) according to the value of SOC [%] and executes it. do it.

  Further, when it is determined in step S23 that the battery 20 does not need to be warmed up (S23: NO), the ECU 24 executes FC power generation priority control in step S26. In this case, if the system load Psys is covered by the FC power Pfc so that no surplus is generated in the power supplied from the FC stack 40 to the load 30, the battery 20 will not be charged. Twenty warm-ups can be avoided.

  Furthermore, when it is determined in step S22 that the FC stack 40 does not need to be warmed up (S22: NO), in step S27, the ECU 24 needs to warm up the battery 20 as in step S23. Determine whether or not. When it is determined that the battery 20 needs to be warmed up (S27: YES), the ECU 24 executes the battery assist priority control in step S25.

  In step S21, when the system load Psys is equal to or less than the system load limit value Psyslmt (S21: YES), or in step S27, it is not necessary to warm up the battery 20 (and the FC stack 40 is also warmed up). If unnecessary (S27: NO), the ECU 24 executes normal control (mode A control to mode C control) in step S28. Thereby, the direct connection state between the FC stack 40 and the battery 20 is released, and execution of the mode D control is prohibited. In the normal control, the system load Psys can be covered by the FC power Pfc.

  In step S21 described above, a determination process based on the comparison between the system load Psys and the system load limit value Psyslmt is performed. Instead of this determination process, the user switches the FC stack 40 as usual by turning on the key switch. It is also possible to activate and then execute the warm-up mode when the user presses the power switch from the on state of the key switch.

[FC control in warm-up mode]
As described above, the warm-up mode (mode D control) is used when the FC stack 40 is warmed up, the FC unit 18 and the battery 20 are directly connected, and the target oxygen concentration Cotgt is basically variable. As a result, the FC current Ifc is made variable. That is, as shown in FIGS. 11 and 13, in the mode D control, ideally, the oxygen concentration Co is adjusted by changing the target oxygen concentration Cotgt while keeping the FC voltage Vfc constant. However, since the DC / DC converter 22 stops the voltage conversion operation, the target FC voltage Vfctgt (= target cell voltage Vcelltgt × number of cells Nfc) is actually the same value as the FC voltage Vfc and the battery voltage Vbat. Become.

  Specifically, in the warm-up mode, when the FC voltage Vfc (or the target FC voltage Vfctgt) and the battery voltage Vbat have substantially the same voltage value, the oxygen concentration Cotgt is changed by changing the target oxygen concentration Cotgt. Adjust.

  Here, specific control of the above-described mode D control (battery assist priority control in step S25, FC power generation priority control in step S26) will be described in detail with reference to FIGS. As described above, in the mode D control, it is determined whether to execute the battery assist priority control or the FC power generation priority control by changing the target FC current Ifctgt.

  FIG. 16 shows a flowchart of control for the FC stack 40 in the warm-up mode (mode D control).

  In step S41, the ECU 24 stops the voltage conversion operation of the DC / DC converter 22 to directly connect the FC unit 18 and the battery 20, and fixes the FC voltage Vfc (target FC voltage Vfctgt) to the battery voltage Vbat. To do.

  In step S42, the ECU 24 calculates a target FC current Ifctgt. That is, in the warm-up mode (mode D control), the target FC current Ifctgt corresponding to the battery assist priority control or the FC power generation priority control corresponding to the FC output possible power Pfcp or the system load Psys is calculated.

  In step S43, the ECU 24 calculates a target oxygen concentration Cotgt corresponding to the target FC current Ifctgt (see FIGS. 11 and 17). FIG. 17 shows an example of the relationship between the target FC current Ifctgt and the target oxygen concentration Cotgt. The relationship as shown in FIG. 17 changes according to the FC voltage Vfc.

  In step S44, the ECU 24 calculates and transmits a command value to each unit in accordance with the target oxygen concentration Cotgt (or target FC current Ifctgt). The command value calculated here includes the rotational speed of the air pump 60 (hereinafter referred to as “air pump rotational speed Nap” or “rotational speed Nap”), and the rotational speed of the water pump 80 (hereinafter referred to as “water pump rotational speed Nwp” or “ ), The opening of the back pressure valve 64 (hereinafter referred to as “back pressure valve opening θbp” or “opening θbp”), and the opening of the circulation valve 66 (hereinafter referred to as “circulation valve opening θc” or “ "Opening angle θc").

  That is, as shown in FIGS. 18 and 19, the target air pump rotation speed Naptgt, the target water pump rotation speed Nwptgt, and the target back pressure valve opening θbptgt are set according to the target oxygen concentration Cotgt. In this case, if the target oxygen concentration Cotgt is lowered, the target air pump rotation speed Naptgt is lowered, and as a result, the flow rate of air supplied to the cathode channel 74 (see FIG. 3) is lowered (the gas supply amount is suppressed). ) Can be easily guessed. Moreover, the target opening degree θctgt of the circulation valve 66 is set to an initial value (for example, an opening degree at which the circulating gas becomes zero).

  In step S45, the ECU 24 determines whether power generation by the FC stack 40 is stable. As the determination, if the lowest cell voltage input from the cell voltage monitor 42 is lower than the voltage obtained by subtracting the predetermined voltage from the average cell voltage {lowest cell voltage <(average cell voltage−predetermined voltage)}, FC It is determined that the power generation of the stack 40 is unstable. As the predetermined voltage, for example, an experimental value, a simulation value, or the like can be used.

  When the power generation is stable (S45: YES), the current process is finished. When the power generation is not stable (S45: NO), in step S46, the ECU 24 increases the opening degree θc of the circulation valve 66 while monitoring the flow rate Qc [g / s] of the circulation gas via the flow rate sensor 70. Then, the flow rate Qc is increased by one step (see FIG. 20). FIG. 20 illustrates a case where the flow rate Qc is increased in the fourth stage when the circulation valve 66 is fully opened, and the maximum flow rate is obtained.

  However, when the opening degree θc of the circulation valve 66 increases, the ratio of the circulation gas in the intake gas sucked into the air pump 60 increases. That is, the intake gas changes such that the ratio of the circulating gas increases in the ratio of new air (air taken from outside the vehicle) and the circulating gas. Therefore, the ability to distribute oxygen to all single cells is improved. Here, the oxygen concentration Co of the circulating gas (cathode off gas) is lower than the oxygen concentration Co of the new air. Therefore, before and after the control of the opening degree θc of the circulation valve 66, the oxygen concentration Co of the gas flowing through the cathode channel 74 decreases when the rotation speed Nap of the air pump 60 and the opening degree θbp of the back pressure valve 64 are the same. Will do.

  Therefore, in step S46, the increase in the rotational speed Nap of the air pump 60 and the opening degree θbp of the back pressure valve 64 are interlocked with the increase in the circulation gas flow rate Qc so that the target oxygen concentration Cotgt calculated in step S43 is maintained. Preferably, at least one of the reductions is performed.

  For example, when the flow rate Qc of the circulating gas is increased, it is preferable to increase the rotational speed Nap of the air pump 60 and increase the flow rate of new air. In this way, the flow rate of the entire gas (mixed gas of new air and circulating gas) toward the cathode flow path 74 increases, so that the oxygen distribution capacity to all single cells is further improved, and the FC stack The power generation performance of 40 is easily recovered.

  Thus, since the circulating gas is merged with the new air while maintaining the target oxygen concentration Cotgt, the volume flow rate [L / s] of the gas flowing through the cathode channel 74 is increased. As a result, the gas whose volume flow rate has increased while the target oxygen concentration Cotgt is maintained can easily reach the entire cathode flow path 74 formed in a complex manner in the FC stack 40. Therefore, the gas is easily supplied to each single cell as well, and instability of power generation of the FC stack 40 is easily resolved. In addition, water droplets (condensed water, etc.) adhering to the surface of the MEA (membrane electrode assembly) and the wall surface surrounding the cathode channel 74 are easily removed.

  In step S47, the ECU 24 determines whether or not the flow rate Qc of the circulating gas detected via the flow rate sensor 70 is equal to or higher than the upper limit value. The upper limit value serving as the determination criterion is set to a value at which the opening degree θc of the circulation valve 66 is fully opened.

  In this case, even if the circulation valve opening degree θc is the same, if the rotation speed Nap of the air pump 60 increases, the flow rate Qc of the circulating gas detected by the flow sensor 70 increases. In association with the number Nap, that is, when the rotation speed Nap of the air pump 60 is increased, the upper limit value is preferably set to be increased.

  If it is determined that the flow rate Qc of the circulating gas is not equal to or greater than the upper limit value (S47: NO), the process returns to step S45. When it is determined that the flow rate Qc of the circulating gas is equal to or higher than the upper limit value (S47: YES), the process proceeds to step S48.

  Here, in steps S46 and S47, the process is executed based on the circulation gas flow rate Qc directly detected by the flow sensor 70, but the process may be executed based on the circulation valve opening θc. That is, in step S46, the circulation valve opening θc is increased in one step (for example, 30 °) in the opening direction. If the circulation valve 66 is fully open in step S47 (S47: YES), the process proceeds to step S48. It is good also as a structure to advance.

  In this case, the circulation gas flow rate Qc [g / s] can also be calculated based on the degree of opening θc of the circulation valve 66, the temperature of the circulation gas, and the map of FIG. As shown in FIG. 21, the density decreases as the temperature of the circulating gas increases, so that the flow rate Qc [g / s] decreases.

  In step S48, the ECU 24 determines whether or not power generation is stable, as in step S45. If the power generation is stable (S48: YES), the current process is terminated. When the power generation is not stable (S48: NO), in step S49, the ECU 24 increases the target oxygen concentration Cotgt by one step (approaches the normal concentration). Specifically, at least one of increasing the rotation speed Nap of the air pump 60 and decreasing the opening θbp of the back pressure valve 64 is performed in one step.

  In step S50, the ECU 24 determines whether or not the target oxygen concentration Cotgt is less than or equal to the target oxygen concentration (normal oxygen concentration Conml) in the normal IV characteristic 200. When the target oxygen concentration Cotgt is less than or equal to the normal oxygen concentration Conml (S50: YES), the process returns to step S48. When the target oxygen concentration Cotgt is not equal to or lower than the normal oxygen concentration Conml (S50: NO), the ECU 24 stops the FC unit 18 in step S51. That is, the ECU 24 stops the supply of hydrogen and air to the FC stack 40 and stops the power generation of the FC stack 40. Then, the ECU 24 turns on a warning lamp (not shown) to notify the driver that the FC stack 40 is abnormal. Note that the ECU 24 supplies electric power from the battery 20 to the motor 14 and continues running of the FC vehicle 10.

  According to the warm-up mode (mode D control) as described above, after the FC unit 18 and the battery 20 are directly connected, the oxygen concentration Co (cathode stoichiometric ratio) is adjusted and supplied to the cathode channel 74. The FC current Ifc can be changed by increasing or decreasing the air flow rate. Further, the battery 20 performs charge / discharge (battery assist priority control or FC power generation) corresponding to the amount of power (FC power Pfc) supplied from the FC stack 40 to the load 30 with respect to the system load Psys. By performing appropriate control of priority control), the battery 20 can be warmed up.

[Normal mode]
Next, the normal control mode (mode A control to mode C control) in step S28 of FIG. 15 will be described with reference to the flowchart of FIG.

  In step S61, the ECU 24 calculates the charge / discharge coefficient α of the battery 20, and calculates the target FC power Pfctgt by multiplying the calculated charge / discharge coefficient α by the system load Psys calculated in step S16 of FIG. 6 (Pfctgt). ← Psys × α).

  Here, the charge / discharge coefficient α is calculated based on the current SOC value input from the SOC sensor 108 and a map (not shown) (characteristic indicating the relationship between the SOC and the charge / discharge coefficient) stored in advance in the ECU 24. The For this map, for example, measured values and simulation values can be used. Here, for convenience of understanding the following description, the charge / discharge coefficient α is described as α = 1 (Pfctgt = Psys).

  Next, in step S62, the ECU 24 determines whether or not the target FC power Pfctgt calculated in step S61 is greater than or equal to the threshold power Pthp (Pfctgt ≧ Pthp).

Here, the threshold power Pthp includes “a cell voltage at which the catalyst is determined not to deteriorate (0.8 V, switching voltage, predetermined voltage)”, “the number Nfc of cells constituting the FC stack 40”, and “the FC stack 40. In the normal I-V characteristic 200 (see FIG. 13), the fixed value shown in the following equation (1) is obtained by multiplying the current value Icellp when the cell voltage is 0.8V. Note that in FIG. 13, the axis of the target FC power Pfctgt is not linear.
Pthp = 0.8 [V] × Nfc × Icellp (1)

  If the target FC power Pfctgt is greater than or equal to the threshold power Pthp (S62: YES), variable voltage / current variable control (mode A control) is executed in step S63 to obtain the target FC power Pfctgt.

  On the other hand, if it is determined in step S62 that the target FC power Pfctgt is less than the threshold power Pthp (step S62: NO), in step S64, the target FC power Pfctgt calculated in step S61 is less than the threshold power Pthq (Pfctgt < Pthq) is determined. Here, the threshold power Pthq is determined in accordance with, for example, the cell voltage Vcell corresponding to Vcell = 0.9 [V], so that the threshold power Pthq is set to a value lower than the threshold power Pthp (Pthq <Pthp). (See FIG. 13).

  If the determination in step S64 is negative, that is, if the target FC power Pfctgt is less than the threshold power Pthp and greater than or equal to the threshold power Pthq (S64: NO, Pthq ≦ Pfctgt <Pthp), step S65. , Voltage fixed / current variable control (mode B control) is executed.

  In the mode B control, the ECU 24 adjusts the step-up rate of the DC / DC converter 22 to thereby set a reference voltage set to a voltage lower than the oxidation-reduction progress region R3 {voltage v2 (= 0.0 in this embodiment). 8V)} is fixed to the target FC voltage Vfctgt, and the target FC current Ifctgt corresponding to the target FC power Pfctgt is calculated. Further, on the assumption that the target FC voltage Vfctgt is the reference voltage, the target oxygen concentration Cotgt corresponding to the target FC current Ifctgt is calculated (see FIGS. 11 and 17).

  Here, the ECU 24 calculates and transmits a command value to each unit according to the target oxygen concentration Cotgt. The command value calculated here includes the air pump speed Nap, the water pump speed Nwp, and the back pressure valve opening degree θbp. That is, the ECU 24 executes the mode B control by setting the target air pump rotation speed Naptgt, the target water pump rotation speed Nwptgt, and the target back pressure valve opening degree θbptgt according to the target oxygen concentration Cotgt.

  Next, in step S66, the ECU 24 determines whether power generation by the FC stack 40 is stable. As the determination, if the lowest cell voltage input from the cell voltage monitor 42 is lower than the voltage obtained by subtracting the predetermined voltage from the average cell voltage {lowest cell voltage <(average cell voltage−predetermined voltage)}, FC It is determined that the power generation of the stack 40 is unstable. As the predetermined voltage, for example, an experimental value, a simulation value, or the like can be used.

  If the power generation is stable (S66: YES), the current process ends. If the power generation is not stable (S66: NO), in step S67, the ECU 24 increases the target oxygen concentration Cotgt by one step (approaches the normal concentration). Specifically, at least one of increasing the rotation speed Nap of the air pump 60 and decreasing the opening θbp of the back pressure valve 64 is performed in one step.

  In step S68, the ECU 24 determines whether the target oxygen concentration Cotgt is less than the normal oxygen concentration Conml. When the target oxygen concentration Cotgt is less than the normal oxygen concentration Conml (S68: YES), the process returns to step S66. When the target oxygen concentration Cotgt is not less than the normal oxygen concentration Conml (S68: NO), the ECU 24 stops the FC unit 18 in step S69. That is, the ECU 24 stops the supply of hydrogen and air to the FC stack 40 and stops the power generation of the FC stack 40. Then, the ECU 24 turns on a warning lamp (not shown) to notify the driver that the FC stack 40 is abnormal. Note that the ECU 24 supplies electric power from the battery 20 to the motor 14 and continues running of the FC vehicle 10.

  If the target FC power Pfctgt is less than the threshold power Pthq in the determination in step S64 described above (S64: YES), mode C control is performed in step S70. In the mode C control, as shown in FIG. 13, the oxygen concentration Co is lowered by lowering the target oxygen concentration Cotgt while the cell voltage Vcell is kept constant (Vcell = v3), and the cell current Icell (FC current Ifc). ) And FC power Pfc. Therefore, also in the mode C control, the control process similar to the above-described mode B control in step S65 and the process related to power generation stability in steps S66 to S69 are executed.

  In the normal control mode described above, the entire system load Psys is basically covered by the FC power Pfc. However, when the FC power Pfc is insufficient, the shortage may be covered by the battery power Pbat.

[FC power generation control]
As described above, as the FC power generation control (S4 in FIG. 5), the ECU 24 controls peripheral devices of the FC stack 40, that is, the air pump 60, the back pressure valve 64, the circulation valve 66, and the water pump 80. Specifically, the ECU 24 controls these devices using a command value (for example, S44 in FIG. 16) of these devices calculated by energy management (S3 in FIG. 5).

[Torque control of motor 14]
FIG. 23 shows a flowchart of torque control of the motor 14 (see FIGS. 1 and 2). This flowchart is executed, for example, in a normal mode (step S28 in FIG. 15 and FIG. 22) performed after the above-described warm-up mode (mode D control) is completed.

  In step S81, the ECU 24 reads the motor rotational speed Nm from the motor rotational speed sensor 152. In step S <b> 82, the ECU 24 reads the opening degree θp of the accelerator pedal 156 from the opening degree sensor 150.

  In step S83, the ECU 24 calculates a temporary target torque Ttgt_p [N · m] of the motor 14 based on the motor rotation speed Nm and the opening degree θp. Specifically, a map that associates the rotational speed Nm, the opening degree θp, and the temporary target torque Ttgt_p is stored in a storage unit (not shown), and the temporary target torque is based on the map, the rotational speed Nm, and the opening degree θp. Ttgt_p is calculated.

  In step S84, the ECU 24 calculates a limit output (motor limit output Pm_lim) [W] of the motor 14 equal to a limit value (limit supply power Ps_lim) [W] of power that can be supplied from the FC system 12 to the motor 14. Specifically, the limit supply power Ps_lim and the motor limit output Pm_lim are calculated from the sum of the FC power Pfc from the FC stack 40 and the limit value of the power that can be supplied from the battery 20 (limit output Pbat_lim) [W]. The power consumption Pa is subtracted (Pm_lim = Ps_lim ← Pfc + Pbat_lim−Pa).

  In step S85, the ECU 24 calculates a torque limit value Tlim [N · m] of the motor 14. More specifically, the torque limit value Tlim is obtained by dividing the motor limit output Pm_lim by the vehicle speed V (Tlim ← Pm_lim / V).

  On the other hand, if it is determined in step S84 that the motor 14 is regenerating, the ECU 24 calculates the limit supply regenerative power Ps_reglim. The limit supply regenerative power Ps_reglim is obtained by subtracting the power consumption Pa of the auxiliary machine from the sum of the limit value of power that can be charged to the battery 20 (limit charge Pbat_chglim) and the FC power Pfc from the FC stack 40 (Ps_reglim = Pbat_chglim + Pfc−Pa). If regeneration is in progress, the ECU 24 calculates the regenerative torque limit value Treglim [N · m] of the motor 14 in step S85. Specifically, a value obtained by dividing the limit supply regenerative power Ps_reglim by the vehicle speed Vs is set as a torque limit value Tlim (Tlim ← Ps_reglim / Vs).

  In step S86, the ECU 24 calculates a target torque Ttgt [N · m]. Specifically, the ECU 24 sets the provisional target torque Ttgt_p, which is limited by the torque limit value Tlim, as the target torque Ttgt. For example, when the temporary target torque Ttgt_p is equal to or less than the torque limit value Tlim (Ttgt_p ≦ Tlim), the temporary target torque Ttgt_p is set as the target torque Ttgt as it is (Ttgt ← Ttgt_p). On the other hand, when the temporary target torque Ttgt_p exceeds the torque limit value Tlim (Ttgt_p> Tlim), the torque limit value Tlim is set as the target torque Ttgt (Ttgt ← Tlim).

  Then, the motor 14 is controlled using the calculated target torque Ttgt.

[Example of warm-up mode (mode D control)]
Next, FIGS. 24 and 25 show time charts for explaining the above-described warm-up mode (mode D control). FIG. 24 illustrates the control at the start of the warm-up mode, and FIG. 25 illustrates the flow from the start to the end of the warm-up mode. In FIG. 24, “Example” illustrates the case where the mode D control of this embodiment is executed, and “Comparative example” illustrates the case where the mode D control is not executed.

  In FIG. 24, the load 30 requests a certain amount of system load Psys regardless of the passage of time.

  Mode A control is executed from time t0 to time t1, which is also the time zone before warm-up.

  From time t1, the DC / DC converter 22 starts to decrease the FC voltage Vfc. At time t3, Vfc≈Vbat, and the FC stack 40 and the battery 20 are directly connected. As a result, after the time point t3, in the embodiment, the mode D control is executed, whereby low-efficiency power generation is performed.

  In the embodiment, the FC current Ifc starts to increase from the time point t1 as the FC voltage Vfc decreases, and maintains a predetermined value in the time period from the time point t3 to the time point t4 when the execution of the mode D control is started. After that, when the target oxygen concentration Cotgt is lowered and the oxygen concentration Co is lowered in a state where the FC voltage Vfc and the battery voltage Vbat are maintained at predetermined values, the FC current Ifc rapidly decreases at the time t4, and after the time t4 Maintain the current value that has dropped in the band. On the other hand, the FC power Pfc gradually increases from the time point t1 to the time point t3 with time changes of the FC voltage Vfc and the FC current Ifc, rapidly decreases at the time point t4, and decreases in the time zone after the time point t4. Maintain power value.

  On the other hand, in the comparative example, since the mode D control described above is not performed, the FC current Ifc does not decrease after time t4.

  In the embodiment, the battery current Ibat starts to decrease from the time point t1, maintains a predetermined value in the time zone from the time point t3 to the time point t4, rapidly increases at the time point t4, and rapidly increases in the time zone after the time point t4. Keep the value. That is, in order to assist the shortage of power supply from the FC stack 40 to the load 30 in the time zone after time t4, the battery 20 supplies the shortage of power (battery power Pbat) to the load 30 (battery assist). Priority control). In this case, as the battery voltage Vbat and the battery current Ibat change with time, the battery power Pbat gradually decreases from the time point t1 to the time point t3, rapidly increases at the time point t4, and increases in the time period after the time point t4. Maintained power value. On the other hand, in the comparative example, the battery current Ibat does not increase after the time point t4, and therefore the battery 20 does not assist the power shortage.

  As a result, the temperature Tfc (water temperature Tw) of the FC stack 40 increases with time from the time point t1. In the embodiment, since the low-efficiency power generation described above is executed, the temperature Tfc reaches the target temperature earlier than in the comparative example.

  Further, in the case of the embodiment, the temperature of the battery 20 (battery temperature Tbat) increases with time from the time point t4. This is because the FC power Pfc for the system load Psys is insufficient due to the execution of the mode D control, and the shortage is covered by the output (discharge) from the battery 20, so the battery 20 is warmed up due to the discharge. Because. Therefore, in the case of the embodiment, the battery temperature Tbat can be quickly reached the target temperature as compared with the comparative example in which insufficient power is not assisted.

  Note that the SOC of the battery 20 decreases toward a predetermined value (FC power generation priority threshold) after the time t4 in order to assist the above-described shortage of power.

  In FIG. 24, the battery assist priority control is described. However, even when the FC power generation priority control is performed, the battery 20 is charged with the surplus power of the FC power Pfc with respect to the system load Psys. Since 20 warm-ups can be performed, the battery temperature Tbat can be quickly reached the target temperature as compared with the comparative example.

  Next, the time chart of FIG. 25 will be described.

  In FIG. 25, the mode B control or the mode C control (voltage fixed / current variable control) is started from time t21, and the FC voltage Vfc is set while executing this voltage fixed / current variable control from time t22 to time t23. The voltage is reduced to the battery voltage Vbat, and the voltage conversion operation by the DC / DC converter 22 is stopped at time t23 when Vfc≈Vbat (becomes a direct connection state), and the mode is shifted to the warm-up mode (mode D control). By executing the warm-up mode, the warm-up of the FC stack 40 is completed first at time t26, and after the warm-up of the battery 20 is completed at time t27, the direct connection state is canceled and voltage conversion by the DC / DC converter 22 is performed. Resume operation. That is, the time zone from time t23 to time t27 is the warm-up mode, and low-efficiency power generation is executed. At time t27, the warm-up mode is canceled and the normal control mode is restored.

  In this case, the FC current Ifc increases / decreases in accordance with the execution of the battery assist priority control or the FC power generation priority control while the FC stack 40 is warmed up from the time t23 to the time t27, and the direct connection state is released after the time t27. It increases with it. In the battery assist priority control, the FC current Ifc is relatively small, and in the FC power generation priority control, the system load Psys is covered by the FC power Pfc, so that the FC current Ifc is relatively large.

  Further, the battery current Ibat increases or decreases in accordance with execution of battery assist priority control or FC power generation priority control. That is, in the battery assist priority control, the battery current Ibat becomes relatively large to assist the shortage of the FC power Ifc with respect to the system load Psys, and in the FC power generation priority control, the system load Psys is covered by the FC power Pfc. Battery current Ibat is relatively small.

  That is, in the warm-up mode, the burden of the battery 20 on the system load Psys may be relatively increased compared to the normal control mode. Therefore, when the system load Psys is high, even when the battery power Pbat and the FC power Pfc are sufficient, the battery 20 is discharged and the battery current Ibat increases.

  In this case, when the SOC is high, priority is given to assisting the FC stack 40 by the battery 20 to cover the system load Psys mainly by the battery power Pbat (battery assist priority control). On the other hand, when the SOC is low, the assist of the FC stack 40 by the battery 20 is suppressed, and the system load Psys is mainly covered by the FC power Pfc (FC power generation priority control).

  In FIG. 25, battery assist priority control is performed from time t22 to time t24 and from time t25 to time t27, and FC power generation priority control is performed from time t24 to time t25.

  In this case, whether to use battery assist priority control or FC power generation priority control is determined by whether or not a predetermined threshold (battery assist priority threshold, FC power generation priority threshold) has been reached for the SOC. That is, when the SOC is equal to or less than the FC power generation priority threshold, the process shifts to FC power generation priority control. In addition, during the FC power generation priority control, when the SOC is equal to or higher than the battery assist priority threshold, the process shifts to battery assist priority control.

  On the other hand, the rotation speed Nap of the air pump 60 is increased or decreased according to the target oxygen concentration Cotgt. In this case, in the case of the battery assist priority control, the FC current Ifc is reduced by suppressing the rotation speed Nap and decreasing the flow rate of the air supplied to the cathode flow path 74, while the FC power generation priority control. If so, the FC current Ifc may be increased by increasing the rotational speed Nap and increasing the flow rate of the air supplied to the cathode channel 74. In addition, after the time t27 when the direct connection state is released, the desired rotation speed Nap is set according to the normal control mode.

[Effects of this embodiment]
As described above, according to this embodiment, the control of the FC voltage Vfc by the DC / DC converter 22 is stopped, and the FC stack 40 and the battery 20 are directly connected, and then based on the SOC size. While changing the amount of air supplied from the air pump 60 to the FC stack 40, the FC stack 40 and the battery 20 are warmed up.

  Specifically, in this embodiment, when the FC vehicle 10 is started, a DC / DC converter is used to adjust the FC voltage Vfc to a voltage lower than the voltage during normal operation of the FC vehicle 10 (voltage during warm-up). After the FC voltage Vfc is lowered by 22, the FC stack 40 and the battery 20 are set (fixed) in a directly connected state of Vfc≈Vbat.

  In the warm-up mode, when the SOC is equal to or higher than the battery assist priority threshold, the assist of the FC stack 40 by the battery 20 is increased by changing the air supply amount so that the output from the battery 20 is prioritized. On the other hand, when the SOC is equal to or lower than the FC power generation priority threshold, the FC stack by the battery 20 is changed by changing the air supply amount so that the output from the FC stack 40 is prioritized. FC power generation priority control that suppresses 40 assists is performed.

  Accordingly, since the FC stack 40 performs low-efficiency power generation with the FC voltage Vfc adjusted to the voltage (battery voltage Vbat) in the warm-up mode by the DC / DC converter 22, the warm-up can be performed quickly. The temperature can be raised quickly. That is, if low-efficiency power generation is performed, the power loss of the FC stack 40 increases and the power loss is converted into heat.

  Further, the FC stack 40 and the battery 20 are connected in parallel to the motor 14, and furthermore, the electric power supplied from the FC stack 40 to the motor 14 during warm-up is due to a decrease in the supply amount of air. Therefore, in the direct connection state, the share of the FC stack 40 relative to the system load Psys is relatively reduced, and the share of the battery 20 that assists the FC stack 40 is relatively increased.

  Therefore, when the system load Psys is relatively large, by increasing the battery power Pbat supplied from the battery 20 (by increasing the discharge amount of the battery 20), the battery 20 warms up due to the discharge. be able to. On the other hand, when the system load Psys is relatively small and can be covered by the FC power Pfc supplied from the FC stack 40, the battery 20 charges a part of the FC power Pfc supplied from the FC stack 40, resulting from the charging. Warm-up can be performed.

  Accordingly, the low-efficiency power generation in the FC stack 40 due to the direct connection between the FC stack 40 and the battery 20 by the DC / DC converter 22 causes the FC stack 40 to warm up quickly, while the FC stack 40 By changing the amount of air supplied to 40, the battery 20 can be quickly warmed up by charging and discharging. Thereby, warming-up with respect to both the FC stack 40 and the battery 20 can be performed effectively.

  When the warm-up of the FC stack 40 and the battery 20 is completed, the direct connection state between the FC stack 40 and the battery 20 (adjustment of the FC voltage Vfc to the warm-up voltage by the DC / DC converter 22) is released, and the DC The warm-up mode is canceled by starting the adjustment of the FC voltage Vfc during normal operation by the DC converter 22.

  As described above, according to this embodiment, it becomes possible to warm up both the FC stack 40 and the battery 20, and after the warm-up is completed, the SOC of the battery 20 is within a predetermined range. Therefore, the original performance of the FC vehicle 10 can be exhibited quickly and sufficiently (100%).

  Moreover, the loss which generate | occur | produces in the DC / DC converter 22 can be reduced because the DC / DC converter 22 will be in a direct connection state at the time of warming-up.

  Further, in the warm-up mode, when the SOC decreases to the FC power generation priority threshold, the FC current Ifc is increased by increasing the air supply amount, and the battery current Ibat is decreased to be set higher than the FC power generation priority threshold. When the SOC becomes higher than the battery assist priority threshold, the FC current Ifc may be decreased and the battery current Ibat may be increased by decreasing the air supply amount.

  Accordingly, when the SOC decreases to the FC power generation priority threshold, the ECU 24 controls to increase the power supplied from the FC stack 40 and suppress the assist of the FC stack 40 by the battery 20 (FC power generation priority). Control) On the other hand, when the SOC becomes higher than the battery assist priority threshold, the power supplied from the FC stack 40 is decreased, and control is performed to increase the assist of the FC stack 40 by the battery 20. (Battery assist priority control). As a result, the temperature raising performance of the FC stack 40 and the battery 20 can be improved, so that the startup performance of the FC vehicle 10 can be improved.

  Further, in this embodiment, if Psys ≦ Psyslmt, execution of the warm-up mode is prohibited. Thereby, when it is not necessary to start the FC vehicle 10 quickly, since the warm-up is not performed actively, wasteful power consumption can be suppressed.

  In the description of this embodiment, since the FC voltage Vfc is higher than the battery voltage Vbat, the direct connection state is described by stepping down the FC voltage Vfc to the battery voltage Vbat by the DC / DC converter 22. That is, the DC / DC converter 22 is configured such that the FC voltage Vfc cannot be set lower than the battery voltage Vbat. The FC stack 40 and the battery 20 are directly connected to the FC stack 40 and the battery 20. Warm-up for both 20 is performed.

  This embodiment is not limited to the above description. If the DC / DC converter 22 is configured to be able to set the FC voltage Vfc to a voltage lower than the battery voltage Vbat, the FC vehicle 10 is activated. In the state where the FC voltage Vfc is set to a voltage lower than the battery voltage Vbat (the voltage during warm-up) by the DC / DC converter 22, both the FC stack 40 and the battery 20 are warmed up, After completion, the low voltage state can be released and the adjustment of the FC voltage Vfc during normal operation by the DC / DC converter 22 can be started.

  In this embodiment, the means or method for adjusting the stoichiometric ratio is one that adjusts the target oxygen concentration Cotgt. However, the present invention is not limited to this, and the target hydrogen concentration can also be adjusted. Further, instead of the target concentration, the target flow rate or both the target concentration and the target flow rate can be used.

  Furthermore, in this embodiment, although the structure provided with the air pump 60 which supplies the air containing oxygen was illustrated, it is good also as a structure provided with the hydrogen pump which supplies hydrogen instead of or in addition to this.

10 ... Fuel cell vehicle (FC vehicle) 12 ... Fuel cell system (FC system)
14 ... Motor 18 ... Fuel cell unit (FC unit)
20 ... Battery 22 ... DC / DC converter 24 ... ECU 30 ... Load 40 ... Fuel cell stack (FC stack, FC)
60 ... Air pump 86, 109 ... Temperature sensor

Claims (4)

In a fuel cell vehicle in which a fuel cell that supplies power to a drive motor and a power storage device that assists the output of the fuel cell are connected in parallel to the drive motor,
Gas supply means for supplying the fuel cell with a gas necessary for power generation in the fuel cell;
By connecting the power storage device and the drive motor, a voltage adjusting unit that is connected in parallel to the fuel cell and adjusts the output voltage of the fuel cell;
Control means for controlling the gas supply means and the voltage adjusting means;
Have
The control means includes
If the remaining capacity of the power storage device is greater than or equal to a first predetermined value when the output voltage is adjusted to a warm-up voltage by the voltage adjusting means when the fuel cell vehicle is started, the gas supply means When the amount of gas supplied to the fuel cell is changed so that the output from the power storage device is prioritized, and the remaining capacity is less than or equal to a second predetermined value lower than the first predetermined value, the gas supply means Performing a warm-up control to change the amount of gas supplied from the fuel cell so that the output from the fuel cell has priority,
When the warm-up of the fuel cell and the power storage device by the warm-up control is completed, the warm-up control is canceled. The fuel cell vehicle according to claim 1, wherein
The control means includes
The warm-up control is performed by directly connecting the fuel cell and the power storage device using the voltage adjusting means, or by adjusting the output voltage of the fuel cell to a voltage lower than the voltage of the power storage device. ,
When the warm-up of the fuel cell and the power storage device is completed, the direct connection state between the fuel cell and the power storage device is canceled and the adjustment of the output voltage is started, or the output voltage is reduced to a low voltage. The warm-up control is canceled by canceling the adjustment and starting the adjustment of the output voltage at a voltage higher than the voltage of the power storage device. The fuel cell vehicle according to claim 2, wherein
In the warm-up control,
When the remaining capacity decreases below the second predetermined value, the output current of the fuel cell is increased and the output current of the power storage device is decreased by increasing the gas supply amount,
When the remaining capacity becomes higher than the first predetermined value, the output current of the fuel cell is decreased and the output current of the power storage device is increased by decreasing the gas supply amount. Fuel cell vehicle. The fuel cell vehicle according to any one of claims 1 to 3,
The fuel cell vehicle, wherein when the required power of a load including the drive motor driven by power supply from the fuel cell is equal to or less than a predetermined value, the control means prohibits the warm-up control.

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