JP2012244712A - Fuel cell vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell vehicle in which both of suitable drivability and excellent fuel efficiency are achieved.SOLUTION: When predetermined high load condition and suppression release condition are met during power generation suppression of FC32 by a power generation suppression means 122, a recovery starting time changing means 126 in FC (fuel cell) vehicle 10 increases a supplying amount of reaction gas supplied to FC32 and a changing amount of at least one of output current and output voltage of FC32 immediately after releasing the power generation suppression, compared with when the suppression release condition is met without meeting the high load condition.

Description

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

  With respect to fuel cell vehicles, techniques for restarting power generation (returning to idle operation) after the fuel cell is idled have been proposed (Patent Documents 1 and 2).

  In Patent Literature 1, a state estimated value indicating a state of the fuel cell in an idle recovery time from when the start operation of the fuel cell in the idle stop state is started to when returning to the idle operation is estimated, and based on the state estimated value To control the output response time of the drive motor (summary). Specifically, the torque command value of the drive motor is designed with a drive motor power consumption response time corresponding to the vehicle speed or the rotation speed of the drive motor in consideration of the idle return time at normal time (1 atm, normal temperature). ([0006]). However, since the idle recovery time changes according to changes in the atmospheric pressure and temperature around the vehicle and the operating state of each auxiliary machine, in Patent Document 1, the output response time of the drive motor is controlled in consideration of these factors. ([0005] to [0011]).

  In Patent Document 2, the power generation operation of the fuel cell stack is restarted when a restart condition is satisfied that the system required power exceeds the threshold value Pref while the power generation operation of the fuel cell stack is stopped (summary). Here, when the battery maximum output power Pbmax is lower than the reference value, the battery power assist is weakened. However, since the threshold value Pref is changed to a value Pref1 lower than the normal value Pref0, The restart is performed earlier than normal, and power is supplied from the fuel cell stack to the motor or the like earlier than normal. As a result, it is intended to suppress a reduction in the power performance of the vehicle after the fuel cell stack is restarted (summary). The battery maximum output power Pbmax is calculated based on the SOC of the battery 58 ([0029]).

JP 2006-280108 A JP 2006-333602 A

  As described above, in Patent Document 1, the estimated state value indicating the state of the fuel cell in the idle recovery time is estimated, and the output response time of the drive motor is controlled based on the estimated state value. As described above, since the estimated state value indicates the state of the fuel cell during the idle recovery time, in Patent Document 1, the output characteristic of the drive motor changes or is limited depending on the state of the fuel cell. For this reason, suitable power performance (drivability) cannot be obtained.

  Further, as described above, in Patent Document 2, when the battery maximum output power is low, the threshold of the system required power for restart is lowered, and the restart of the fuel cell stack is accelerated. The battery maximum output power is calculated based on the SOC of the battery. For this reason, in Patent Document 2, even when the system required power is low, the fuel cell stack is restarted earlier than usual. Therefore, when both the system required power and the battery maximum output power are low, in Patent Document 2, the fuel consumption is reduced.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a fuel cell vehicle capable of achieving both suitable drivability and excellent fuel efficiency.

  A fuel cell vehicle according to the present invention includes a travel motor, a fuel cell that supplies power to the travel motor, a power storage device that supplies power to the travel motor and charges regenerative power from the travel motor, A converter provided on the power storage device side, which controls the output voltage of the fuel cell by transforming the output voltage of the power storage device; a reaction gas supply means for supplying a reaction gas to the fuel cell; and power generation of the fuel cell Power generation suppression means for lowering the output of the fuel cell and the operating amount of the reaction gas supply means to a power generation suppression region lower than a normal operation region when the power generation suppression condition for suppressing the power generation is satisfied, and canceling the power generation suppression of the fuel cell Suppression release means for returning the output of the fuel cell and the operating amount of the reaction gas supply means to the normal operation region when a suppression release condition is established, When the predetermined high load condition and the suppression release condition are satisfied during power generation suppression by the power generation suppression means, the power generation suppression is suppressed as compared with the case where the suppression release condition is satisfied without the high load condition being satisfied. And a return rise speed changing means for increasing at least one change amount of the supply amount of the reaction gas supplied to the fuel cell and the output current and output voltage of the fuel cell immediately after the release.

  According to the present invention, when the predetermined high load condition and the suppression release condition are satisfied while the power generation of the fuel cell is suppressed, the generation suppression is suppressed compared to the case where the suppression release condition is satisfied without the high load condition being satisfied. Immediately after release, the amount of reaction gas supplied to the fuel cell and the amount of change in at least one of the output current and output voltage of the fuel cell are increased. Thereby, when canceling the power generation suppression of the fuel cell, if a high load is required, it is possible to ensure suitable drivability (power performance). Further, when canceling the power generation suppression of the fuel cell, if a high load is not required, at least one of the supply amount of the reactive gas supplied to the fuel cell immediately after the cancellation of the power generation suppression, the output current and the output voltage of the fuel cell Since the amount of change is not increased (because normal control is used), excellent fuel efficiency can be maintained.

  When the operating amount of the reaction gas supply means follows the target output of the fuel cell and the high load condition and the suppression release condition are satisfied during power generation suppression by the power generation suppression means, the return rising speed changing means is Changes in the operating amount of the reaction gas supply means and the supply amount of the reaction gas by setting the target output of the fuel cell higher than when the suppression release condition is satisfied without the high load condition being satisfied The amount may be increased.

  As a result, when canceling the power generation suppression of the fuel cell, it is possible to prevent the shortage of the reaction gas even if a high load is required, and it is possible to suppress the deterioration of the fuel cell due to the shortage of the reaction gas. Become. Further, when canceling the power generation suppression of the fuel cell, drivability can be more reliably maintained by suppressing the shortage of reaction gas when a high load is required.

  When the high load condition and the suppression release condition are satisfied during power generation suppression by the power generation suppression unit, the return rising speed changing unit is compared with the case where the suppression release condition is satisfied without the high load condition being satisfied. Thus, the rate of change of the output voltage of the fuel cell may be increased by increasing the feedback gain of the converter. Thereby, when canceling the power generation suppression of the fuel cell, even if a high load is required, it is possible to draw a current from the fuel cell satisfactorily by rapidly changing the output voltage of the fuel cell. As a result, even immediately after canceling power generation suppression, the output of the fuel cell can be made to follow the required load quickly, so drivability can be further improved.

  When the high load condition and the suppression release condition are satisfied during power generation suppression by the power generation suppression unit, the return rising speed changing unit is compared with the case where the suppression release condition is satisfied without the high load condition being satisfied. Thus, the initial output voltage of the converter after the cancellation of power generation suppression may be lowered. Due to the characteristics of the fuel cell, it is possible to increase the output current and output (generated power) of the fuel cell when the output voltage of the fuel cell is low. The converter also controls the output voltage of the fuel cell by adjusting the output voltage of the power storage device. According to the above configuration, when canceling the power generation suppression of the fuel cell, if a high load is required, the initial value of the output voltage of the converter (corresponding to the output voltage of the fuel cell) is reduced, so that The output can be increased rapidly. As a result, even immediately after canceling power generation suppression, the output of the fuel cell can be made to follow the required load quickly, so drivability can be further improved.

  According to the present invention, when the predetermined high load condition and the suppression release condition are satisfied while the power generation of the fuel cell is suppressed, the generation suppression is suppressed compared to the case where the suppression release condition is satisfied without the high load condition being satisfied. Immediately after release, the amount of reaction gas supplied to the fuel cell and the amount of change in at least one of the output current and output voltage of the fuel cell are increased. Thereby, when canceling the power generation suppression of the fuel cell, if a high load is required, it is possible to ensure suitable drivability. Further, when canceling the power generation suppression of the fuel cell, if a high load is not required, at least one of the supply amount of the reactive gas supplied to the fuel cell immediately after the cancellation of the power generation suppression, the output current and the output voltage of the fuel cell Since the amount of change is not increased (because normal control is used), excellent fuel efficiency can be maintained.

1 is a schematic configuration diagram of a fuel cell vehicle according to an embodiment of the present invention. It is a figure which shows the detail of the DC / DC converter in the said embodiment. It is a flowchart of basic control in an electronic control unit (ECU). It is a flowchart (detail of S2 of FIG. 3) which calculates a system load. It is a figure which shows the relationship between the present motor rotation speed and motor expected power consumption. 4 is a flowchart in which the ECU selects a power generation mode. It is a flowchart of control at the time of shifting from the power generation halt mode to the normal power generation mode. It is a flowchart (detail of S31 of FIG. 7) which determines the necessity of implementation of the countermeasure against deterioration of drivability. 8 is a flowchart (details of S32 in FIG. 7) for determining whether or not a drivability deterioration countermeasure needs to be terminated. It is a flowchart (detail of S33 of FIG. 7) which performs control according to the determination result of step S31 of FIG. 7, and S32. It is a flowchart (detail of S4 of FIG. 3) of FC electric power generation control. It is a figure which shows the map which prescribes | regulates the relationship between the electric power generation voltage of a fuel cell stack, and the target current of a fuel cell stack. It is a figure which shows the map which prescribes | regulates the relationship between the target electric current of a fuel cell stack, and the target rotation speed of an air pump. It is a figure which shows the map which prescribes | regulates the relationship between the target electric current of a fuel cell stack, and the target opening degree of a back pressure valve. It is a flowchart (details of S5 of FIG. 3) of torque control of the motor. It is a figure which shows the example of the time chart at the time of using the various controls in this embodiment and a comparative example. It is a block diagram which shows schematic structure of the 1st modification of the electric power system which concerns on the said embodiment. It is a block diagram which shows schematic structure of the 2nd modification of the electric power system which concerns on the said embodiment. It is a block diagram which shows schematic structure of the 3rd modification of the electric power system which concerns on the said embodiment.

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

  The power supply system 12 includes a fuel cell unit 18 (hereinafter referred to as “FC unit 18”) (reactive gas supply means), a battery 20, a DC / DC converter 22, and an electronic control unit 24 (hereinafter referred to as “ECU 24”). And have.

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

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

  The motor 14 and the inverter 16 are collectively referred to as a load 30. However, the load 30 may include components such as an air pump 36 and a water pump 68 described later.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[1-6. ECU 24]
The ECU 24 controls the motor 14, the inverter 16, the FC unit 18, the battery 20, and the DC / DC converter 22 via the communication line 78 (FIG. 1). In the control, a program stored in a memory (ROM) is executed, and various kinds of sensors such as voltage sensors 42, 46, 70, 90, 96, current sensors 44, 72, 94, 100, pressure sensors 64, 66, etc. The detection value of the sensor is used.

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

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

  The ECU 24 of this embodiment includes a normal power generation function 120, a power generation suppression function 122, a suppression release function 124, and a return rising speed change function 126. The normal power generation function 120 is a function for controlling a normal power generation mode to be described later. The power generation suppression function 122 is a function for controlling a power generation suspension mode, which will be described later, and suppresses power generation by the FC 32. The suppression cancellation function 124 is a function for canceling the power generation suppression of the FC 32 by the power generation suppression function 122. The return rising speed changing function 126 is a function for changing the speed (return rising speed) for returning to the normal power generation mode when the power generation suppression of the FC 32 is released. Details of these functions 120, 122, 124, 126 will be described later.

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

[2-1. Basic control]
FIG. 3 shows a flowchart of basic control in the ECU 24. In step S1, the ECU 24 determines whether or not the main SW 118 is on. If the main SW 118 is not on (S1: NO), step S1 is repeated. If the main SW 118 is on (S1: YES), the process proceeds to step S2. In step S2, the ECU 24 calculates a load (system load Ls) [W] required for the power supply system 12.

  In step S <b> 3, the ECU 24 performs energy management of the power supply system 12. The energy management here is mainly processing for calculating the amount of power generated by the FC 32 (FC power Pfc) and the output of the battery 20 (battery output Pbat), while suppressing the deterioration of the FC stack 32 and the entire power supply system 12. It is intended to make the output more efficient.

  In step S4, the ECU 24 controls peripheral devices of the FC stack 32, that is, the air pump 36, the back pressure valve 60, and the water pump 68 (FC power generation control) based on the result of energy management in step S3. 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 118 is off. If the main SW 118 is not off (S6: NO), the process returns to step S2. If the main SW 118 is off (S6: YES), the current process is terminated.

[2-2. Calculation of system load Ls]
FIG. 4 shows a flowchart for calculating the system load Ls (details of S2 in FIG. 3). In step S <b> 11, the ECU 24 reads the opening degree θ of the accelerator pedal 116 from the opening degree sensor 110. In step S <b> 12, the ECU 24 reads the rotational speed Nm [rpm] of the motor 14 from the rotational speed sensor 112.

  In step S13, the ECU 24 calculates the expected power consumption Pm [W] of the motor 14 based on the opening degree θ and the motor rotation speed Nm. Specifically, in the map shown in FIG. 5, the relationship between the rotational speed Nm and the predicted power consumption Pm is stored for each opening degree θ. For example, when the opening degree θ is θ1, the characteristic 130 is used. Similarly, when the opening degree θ is θ2, θ3, θ4, θ5, and θ6, the characteristics 132, 134, 136, 138, and 140 are used, respectively. And after specifying the characteristic which shows the relationship between rotation speed Nm and estimated power consumption Pm based on opening degree (theta), the predicted 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 36, a water pump 68 and an air conditioner (not shown), and a low-voltage auxiliary machine including a low-voltage battery, an accessory (not shown), and an ECU 24. included. For example, in the case of the air pump 36 and the water pump 68, the rotational speeds Nap and Nwp [rpm] are read. If it is the air conditioner, its 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 adds the expected power consumption Pm of the motor 14 and the power consumption Pa of the auxiliary machine to calculate the expected power consumption (that is, the system load Ls) of the FC vehicle 10 as a whole.

[2-3. Energy management]
As described above, in the energy management in the present embodiment, the power generation amount of FC 32 (FC power Pfc) and the output of battery 20 (battery output Pbat) are mainly calculated.

(2-3-1. FC32 output control)
Due to the characteristics of FC32, FC voltage Vfc is basically equal to secondary voltage V2 of DC / DC converter 22. Therefore, the FC voltage Vfc can be controlled by adjusting the secondary voltage V2 by the DC / DC converter 22. Further, the FC current Ifc can be controlled by controlling the FC voltage Vfc on the current-voltage (IV) characteristics of the FC32. Therefore, in the present embodiment, the FC voltage Vfc and the FC current Ifc are controlled using a target value of the secondary voltage V2 (hereinafter referred to as “target secondary voltage V2tgt”).

(2-3-2. Power generation mode)
In the present embodiment, the normal power generation mode and the power generation suspension mode are used as the operation mode (power generation mode) regarding the power generation of the FC 32. The normal power generation mode is a mode used in normal travel (travel that is not the pause mode), and is realized by the normal power generation function 120 of the ECU 24. The power generation suspension mode is a mode in which the FC 32 actively stops power generation (in other words, suppresses the power generation of the FC 32) when the main SW 118 (FIG. 1) is on, and is realized by the power generation suppression function 122. The positive power generation (or suppression of power generation) here refers to power generation of the FC 32 based on a command from the ECU 24, and does not include power generation by residual gas. The selection of the normal power generation mode and the power generation suspension mode is executed by the suppression release function 124. In addition, the FC32 power generation is suppressed in the power generation suspension mode, but the suppression is not released immediately even when the power generation suspension mode is switched to the normal power generation mode, and the vehicle speed V [km / h] becomes a predetermined value or more. Is released.

  FIG. 6 is a flowchart in which the ECU 24 (suppression release function 124) selects the power generation mode. In step S <b> 21, the ECU 24 calculates the vehicle speed V based on the rotational speed Nm of the motor 14 from the rotational speed sensor 112. In step S22, the ECU 24 determines whether or not the power generation suspension mode is being selected. Specifically, when the power generation mode flag FLG1 indicating which of the normal power generation mode and the power generation suspension mode is selected is “0”, it is determined that the power generation mode is normal, and when it is “1”, It is determined that the power generation suspension mode is set. When the power generation mode flag FLG1 is 0 and the power generation suspension mode is not selected (S22: NO), the process proceeds to step S23. When the power generation mode flag FLG1 is 1 and the power generation suspension mode is being selected (S22: YES), the process proceeds to step S25.

  In step S23, the ECU 24 determines whether or not the power generation suspension mode should be started. Specifically, it is determined whether or not the vehicle speed V calculated in step S21 is equal to or less than a first vehicle speed threshold value THV1 (hereinafter also referred to as “threshold value THV1”) for determining whether or not to start the power generation suspension mode. judge. When the vehicle speed V is not less than the threshold value THV1 and the power generation suspension mode is not started (S23: NO), the process proceeds to step S27. When the vehicle speed V is equal to or less than the threshold value THV1 and the power generation suspension mode is started (S23: YES), in step S24, the ECU 24 changes the power generation mode flag FLG1 from “0” to “1”.

  In subsequent step S25, the ECU 24 determines whether or not the power generation suspension mode should be terminated. Specifically, it is determined whether or not the vehicle speed V calculated in step S21 is equal to or higher than a second vehicle speed threshold value THV2 (hereinafter also referred to as “threshold value THV2”) for determining whether or not to end the power generation suspension mode. judge. In the present embodiment, the threshold value THV2 is set to a value higher than the threshold value THV1 (THV2> THV1). Thereby, it becomes possible to give a hysteresis characteristic to the selection of the power generation suspension mode, and it is possible to prevent the generation mode from being switched excessively.

  When the vehicle speed V is not equal to or higher than the threshold value THV2 and the power generation suspension mode is not terminated (S25: NO), in step S26, the ECU 24 sets the power generation mode flag FLG1 to “1” and selects the power generation suspension mode. When the power generation suspension mode is not started in step S23 (S23: NO) or when the vehicle speed V is equal to or higher than the threshold value THV2 in step S25 (S25: YES), in step S27, the ECU 24 sets “0” to the power generation mode flag FLG1. Set and select normal power generation mode.

(2-3-3. Control when shifting from power generation halt mode to normal power generation mode)
In the present embodiment, when a high load (high system load Ls) is required immediately after the power generation suspension mode (low load state), control is performed to quickly increase the output of the FC 32. Thereby, it becomes possible to prevent the drivability (power performance) of the vehicle 10 from deteriorating because the output of the FC 32 cannot follow the required load.

(2-3-3-1. Control when shifting from power generation halt mode to normal power generation mode)
FIG. 7 is a flowchart of control when shifting from the power generation suspension mode to the normal power generation mode. In step S31, the ECU 24 determines whether it is necessary to implement countermeasures for deterioration of drivability (hereinafter also referred to as “DR”). In step S32, the ECU 24 determines whether or not the drivability deterioration countermeasure needs to be terminated. In step S33, the ECU 24 executes control of each part according to the determination results of steps S31 and S32. The implementation and implementation of the drivability deterioration countermeasure and the deterioration countermeasure are executed by the return rising speed changing function 126 of the ECU 24.

(2-3-3-2. Determination of Necessity of Implementing Countermeasures for Deterioration of Drivability)
FIG. 8 is a flowchart (details of S31 in FIG. 7) for determining whether or not countermeasures for drivability deterioration need to be implemented. In step S41, the ECU 24 determines whether or not the high load condition is being determined immediately after the cancellation of the power generation suspension mode. The high load condition is a condition for determining whether or not a high load is required. For the determination in step S41, a power generation halt mode release flag FLG2 (hereinafter also referred to as “flag FLG2”) indicating whether or not it is immediately after the power generation suspension mode is canceled is used. That is, the flag FLG2 is set to “1” if it is immediately after the cancellation of the power generation suspension mode, and is set to “0” if it is not immediately after the cancellation.

  When the flag FLG2 is 1 and the high load condition is being determined (S41: YES), the process proceeds to step S45. When the flag FLG2 is 0 and the high load condition is not being determined (S41: NO), the process proceeds to step S42.

  In step S42, the ECU 24 determines whether or not the power generation suspension mode has been canceled in the current calculation cycle. This determination is made based on whether or not the power generation mode flag FLG1 described above was “1” in the previous calculation cycle, but switched to “0” in the current calculation cycle. If the power generation suspension mode has not been canceled in the current calculation cycle (S42: NO), the process proceeds to step S50. When the power generation suspension mode is canceled in the current calculation cycle (S42: YES), the process proceeds to step S43.

  In step S43, the ECU 24 starts determining the high load condition. Specifically, “1” is set in the power generation halt mode release flag FLG2. In step S44, the ECU 24 sets a determination period for the high load condition. Specifically, counting of a first timer T1 (hereinafter also referred to as “timer T1”) is started.

  When the high load condition is being determined in step S41 (S41: YES) or after step S44, in step S45, the ECU 24 determines whether or not the high load condition determination period has ended. Specifically, it is determined whether or not the timer T1 is equal to or greater than a first timer threshold value THT1 (hereinafter also referred to as “threshold value THT1”) for determining whether or not the determination period of the high load condition has ended. . When the timer T1 is equal to or greater than the threshold value THT1 (S45: YES), in step S46, the ECU 24 sets “0” to the power generation suspension mode release flag FLG2, and ends the determination of the high load condition. After step S46, the process proceeds to step S50. When the timer T1 is not equal to or greater than the threshold value THT1 (S45: NO), the process proceeds to step S47.

  In step S47, as a first high load condition (hereinafter referred to as “high load condition 1”), the ECU 24 uses a third vehicle speed threshold THV3 (hereinafter also referred to as “threshold THV3”) for determining whether the vehicle speed V is high. .) It is determined whether it is above. When the vehicle speed V is not equal to or higher than the threshold value THV3 (S47: NO), the process proceeds to step S50. When the vehicle speed V is equal to or higher than the threshold value THV3 (S47: YES), the process proceeds to step S48.

  In step S48, as the second high load condition (hereinafter referred to as “high load condition 2”), the ECU 24 uses a first opening threshold value for determining whether the accelerator opening θ from the opening sensor 110 is high. It is determined whether or not it is greater than THθ1 (hereinafter also referred to as “threshold THθ1”). If the accelerator opening θ is not equal to or greater than the threshold THθ1 (S48: NO), the process proceeds to step S50. If the accelerator opening θ is equal to or greater than the threshold THθ1 (S48: YES), the process proceeds to step S49.

  In step S <b> 49, the ECU 24 determines that it is necessary to take measures to reduce drivability. Specifically, “1” indicating that the implementation is required is set in the DR deterioration flag FLG3 (hereinafter also referred to as “flag FLG3”) indicating whether or not countermeasures for drivability deterioration are necessary.

  When it is not necessary to cancel the power generation suspension mode at step S42 (S42: NO), after step S46, when the high load condition 1 is not satisfied at step S47 (S47: NO), or at step S48, the high load condition 2 is If not established (S48: NO), in step S50, the ECU 24 determines that it is not necessary to take measures to reduce drivability. Specifically, “0” indicating that the implementation is not necessary is set in the DR deterioration flag FLG3.

(2-3-3-3. Determining Necessity of Ending Drivability Deterioration Countermeasures)
FIG. 9 is a flowchart (details of S32 in FIG. 7) for determining whether or not to end the drivability deterioration countermeasure. In step S61, the ECU 24 determines whether or not the DR deterioration flag FLG3 is “1” indicating that it is necessary to take a countermeasure for deterioration of drivability. When the flag FLG3 is not “1” (S61: NO), the process proceeds to step S66. When the flag FLG3 is “1” (S61: YES), the process proceeds to step S62.

  In step S62, the ECU 24 determines whether or not countermeasures for drivability deterioration are already being implemented. Specifically, it is determined whether or not a second timer T2 (hereinafter, also referred to as “timer T2”) that sets the implementation period of the drivability deterioration countermeasure is zero. When the timer T2 is not zero and the countermeasure for the deterioration of drivability is already being implemented (S62: YES), the process proceeds to step S64. When the timer T2 is zero and the countermeasure for the deterioration of drivability has not been started yet (S62: NO), the process proceeds to step S63.

  In step S63, the ECU 24 sets an implementation period for measures to reduce drivability. Specifically, the count of the second timer T2 is started.

  In step S64, the ECU 24 determines whether or not the implementation period of the drivability deterioration countermeasure has ended. Specifically, it is determined whether or not the timer T2 is zero. If the timer T2 is not 0 (S64: NO), the process proceeds to step S65. When the timer T2 is zero (S64: YES), the process proceeds to step S66.

  In step S65, the ECU 24 determines whether or not the high load state has ended. Specifically, it is determined whether or not the accelerator opening θ is equal to or smaller than a second opening threshold THθ2 (hereinafter also referred to as “threshold THθ2”) for determining the end of the high load state. The threshold value THθ2 is set to a value smaller than the threshold value THθ1 (THθ2 <THθ1).

  If the accelerator opening θ is not less than the threshold THθ2 and the high load state has not ended (S65: NO), the current calculation process is terminated and the process proceeds to the next calculation cycle. If the DR deterioration flag FLG3 is not “1” in step S61 (S61: NO), the drivability deterioration countermeasure implementation period ends in step S64 (S64: YES), or the accelerator opening θ is equal to or less than the threshold THθ2 in step S65. If the high load state has ended (S65: YES), in step S66, the ECU 24 sets “0” to the flag FLG3, and ends the implementation of the drivability deterioration countermeasure.

(2-3-3-4. Determining the necessity for termination of drivability deterioration countermeasures)
FIG. 10 is a flowchart (details of S33 in FIG. 7) for executing control according to the determination results in steps S31 and S32 in FIG. In step S71, the ECU 24 determines whether or not countermeasures for drivability deterioration are being implemented. This determination is made based on the DR deterioration determination flag FLG3. That is, when the flag FLG3 is “0”, the countermeasure for the deterioration is not being implemented, and when the flag FLG3 is “1”, the countermeasure for the deterioration is being implemented. When the flag FLG3 is “1” and the countermeasure for deterioration of drivability is being implemented (S71: YES), the process proceeds to step S72.

  Steps S <b> 72 to S <b> 75 are processes as countermeasures for deterioration of drivability. That is, in step S72, the ECU 24 determines whether or not the initial value of the target secondary voltage V2tgt (hereinafter referred to as “initial value V2ini”) has been newly set after the flag FLG3 is switched. As described above, the FC voltage Vfc can be controlled by using the target secondary voltage V2tgt. If the initial value V2ini has been set (S72: YES), the process proceeds to step S74. If the initial value V2ini has not been set (S72: NO), the process proceeds to step S73.

  In step S73, the ECU 24 sets a value obtained by subtracting the correction value α (FIG. 16) from the normal initial value V2ini (the initial value V2ini set in step S77) as the current initial value V2ini. The correction value α is a value that is subtracted from the normal initial value V2ini in order to increase the output of the FC32 immediately after canceling the power generation suppression of the FC32, and is larger than zero (α> 0). That is, in the present embodiment, the target secondary voltage V2tgt in the power generation suspension mode is set higher than the open circuit voltage (OCV) of the FC 32 (FIG. 16). This is because making the secondary voltage V2 higher than the FC voltage Vfc prevents the power generation of the FC32 more reliably. For this reason, the correction value α is set to a value at which the target secondary voltage V2tgt is equal to the OCV or a value in the vicinity thereof. Thereby, it becomes possible to generate and increase the output from the FC 32 immediately after canceling the power generation suppression of the FC 32 (more details will be described with reference to FIG. 16).

  In step S74, the ECU 24 calculates a target value (target FC current Ifctgt) of the FC current Ifc. While countermeasures against drivability deterioration are being implemented, a value obtained by multiplying the target FC current Ifctgt in the normal state (S78) by the coefficient β is set as the target FC current Ifctgt. The coefficient β is a coefficient for increasing the output of the FC 32 during the implementation of countermeasures against deterioration, and is larger than 1 (β> 1).

  In step S75, the ECU 24 calculates a gain (hereinafter referred to as "FB gain Gfb" or "converter FB gain Gfb") used in feedback (FB) control of the DC / DC converter 22. While countermeasures against drivability deterioration are being implemented, a value obtained by multiplying the FB gain Gfb at the normal time (S79) by the coefficient γ is set as the FB gain Gfb. The coefficient γ is a coefficient for increasing the output of the FC 32 during the implementation of countermeasures against deterioration, and is larger than 1 (γ> 1).

  Returning to step S71, if the DR deterioration flag FLG3 is “0” and the countermeasure for deterioration of drivability is not being implemented (S71: NO), the process proceeds to step S76.

  Steps S76 to S79 are normal processing (when measures for deterioration of drivability are not implemented). That is, in step S76, the ECU 24 determines whether or not the initial value V2ini of the target secondary voltage V2tgt has been newly set after the flag FLG3 is switched. If the initial value V2ini has been set (S76: YES), the process proceeds to step S78. If the initial value V2ini has not been set (S76: NO), the process proceeds to step S77.

  In step S77, the ECU 24 sets a normal initial value V2ini. As described above, the normal initial value V2ini is set to a value higher than the OCV.

  In step S78, the ECU 24 calculates the target FC current Ifctgt. The target FC current Ifctgt is basically set according to the system load Ls calculated in the flowchart of FIG. That is, a target value of FC power Pfc (hereinafter referred to as “target FC power Pfctgt”) is assigned according to the system load Ls. In the present embodiment, the target FC current Ifctgt is calculated according to the target FC power Pfctgt.

  However, if the FC current Ifc changes abruptly, the FC32 may be deteriorated. For this reason, in the present embodiment, the maximum value (allowable maximum change amount) of the change amount of the target FC current Ifctgt for each calculation cycle is set, and rate limit control that does not allow any further change is performed. However, in the above-described step S74, while the countermeasure for the deterioration of drivability is being implemented, the allowable maximum change amount is also multiplied by the coefficient β by the normal value.

  In step S79, the ECU 24 calculates the FB gain Gfb of the DC / DC converter 22. That is, in the present embodiment, the target FC voltage Vfctgt to be controlled by the DC / DC converter 22 is set according to the target FC current Ifctgt. That is, the FC 32 of the present embodiment has the same current-voltage characteristics (IV characteristics) as a general fuel cell. Therefore, the target FC voltage Vfctgt can be set according to the target FC current Ifctgt.

  Further, due to the characteristics of FC32, the FC voltage Vfc is substantially equal to the secondary voltage V2 during normal output of FC32. For this reason, the ECU 24 can control the FC voltage Vfc by controlling the secondary voltage V <b> 2 by the DC / DC converter 22. In other words, the ECU 24 controls the DC / DC converter 22 so that the secondary voltage V2 becomes equal to the target FC voltage Vfctgt.

  The FB gain Gfb is multiplied by a deviation ΔV2 (= V2tgt−V2) between the target secondary voltage V2tgt and the actual secondary voltage V2.

  The ECU 24 of the present embodiment calculates a feedforward term (hereinafter referred to as “FF term”) based on the target secondary voltage V2tgt and V1 detected by the voltage sensor 90. The FF term is a quotient V1 / V2tgt between the primary voltage V1 and the target secondary voltage V2tgt. Further, the ECU 24 calculates a feedback term (hereinafter referred to as “FB term”) by PID control (proportional / integral / derivative control) using a product of the deviation ΔV2 and the coefficient β. Then, the target duty DUTtar as the sum of the FF term and the FB term is calculated. The target duty DUTtar defines the output period [s] of the drive signals UH and UL in one switching cycle [s].

  As described above, in the calculation of the FB term, by multiplying the deviation ΔV2 by the coefficient β larger than 1, the FB term becomes large, so that the actual secondary voltage V2 can be converged earlier to the target secondary voltage V2tgt. It becomes like this.

[2-4. FC power generation control]
As described above, as the FC power generation control (S4 in FIG. 3), the ECU 24 controls peripheral devices of the FC stack 32, that is, the air pump 36, the back pressure valve 60, and the water pump 68.

  FIG. 11 is a flowchart of FC power generation control. In step S <b> 81, the ECU 24 reads the FC voltage Vfc from the voltage sensor 42. In step S82, the ECU 24 sets a target current (target FC current Ifctgt) [A] of the FC stack 32 based on the FC voltage Vfc. Specifically, the map shown in FIG. 12 is stored in advance in storage means (not shown) of the ECU 24. Then, the target FC current Ifctgt corresponding to the FC voltage Vfc is read from the map.

  In step S83, the ECU 24 sets a target value (target rotational speed Naptgt) [rpm] of the rotational speed Nap of the air pump 36 based on the target FC current Ifctgt. Specifically, the map shown in FIG. 13 is stored in advance in the storage unit of the ECU 24. Then, the target rotational speed Naptgt corresponding to the target FC current Ifctgt is read from the map.

  In step S84, the ECU 24 sets a target value (target opening degree θvtgt) [degree] of the opening degree θv of the back pressure valve 60 based on the target FC current Ifctgt. Specifically, the map shown in FIG. 14 is stored in advance in the storage means of the ECU 24. Then, the target opening degree θvtgt corresponding to the target FC current Ifctgt is read from the map.

  In step S85, the ECU 24 performs feedback control based on the flow rate FR in the path 56 for the rotation speed Nap of the air pump 36. Specifically, the ECU 24 determines the difference between the rotational speed Nap and the target rotational speed Naptgt based on the pressure P2 (corresponding to the flow rate FR) from the pressure sensor 66. That is, the relationship between the pressure P2 and the rotation speed Nap is stored in advance as a map, and the rotation speed Nap is calculated based on the map and the pressure P2. Then, the difference between the calculated rotation speed Nap and the target rotation speed Naptgt is calculated, and the difference is reflected in the feedback term.

  In step S <b> 86, the ECU 24 performs feedback control based on the pressures P <b> 1 and P <b> 2 from the pressure sensors 64 and 66 for the opening degree θv of the back pressure valve 60. Specifically, the ECU 24 determines the difference between the opening θv and the target opening θvtgt based on the pressures P1 and P2 from the pressure sensors 64 and 66. That is, the relationship between the pressures P1, P2 and the opening degree θv is stored in advance as a map, and the opening degree θv is calculated based on the map and the pressures P1, P2. Then, the difference between the calculated opening degree θv and the target rotational speed Naptgt is calculated, and the difference is reflected in the feedback term.

[2-5. Torque control of motor 14]
FIG. 15 shows a flowchart of torque control of the motor 14. In step S91, the ECU 24 reads the motor rotational speed Nm from the rotational speed sensor 112. In step S92, the ECU 24 reads the opening degree θ of the accelerator pedal 116 from the opening degree sensor 110.

  In step S93, 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 θ. Specifically, a map that associates the rotational speed Nm, the opening degree θ, 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 θ. Ttgt_p is calculated.

  In step S94, 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 power supply 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 32 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 S95, 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).

  In step S96, 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.

3. Examples of Various Controls FIG. 16 shows examples of time charts when various controls in the present embodiment and comparative examples are used. The comparative example here is control that does not take measures against deterioration of drivability, that is, control that uses steps S76 to S79 in FIG. 10 and does not use steps S72 to S75. Further, regarding the target FC current Ifctgt, the target secondary voltage V2tgt, and the FC current Ifc of FIG. 16, the solid line indicates the present embodiment, and the broken line indicates the comparative example.

  Until the time point t1 in FIG. 16, since the vehicle speed V is less than the threshold value THV2 (S25: NO in FIG. 6), the power generation suspension mode is selected (S26). Note that the vehicle speed V increases because the FC current Ifc is constant until the time point t1 because electric power is supplied from the battery 20 to the motor 14.

  At time t1, the vehicle speed V becomes equal to or higher than the threshold value THV2 (S25: YES), so the mode is switched to the normal power generation mode (S27). However, at time point t1, the vehicle speed V is less than the fourth vehicle speed threshold value THV4 (hereinafter also referred to as “threshold value THV4”) that determines whether to cancel the suppression of power generation by the FC 32, and therefore the suppression release is not performed.

  At time t1, the timer T1 is not equal to or greater than the threshold value THT1 (S45: NO in FIG. 8), the vehicle speed V is equal to or greater than the threshold value THV3 (S47: YES), and the accelerator opening θ is equal to or greater than the threshold value THθ1 (S48: YES). Accordingly, countermeasures for deterioration of drivability are implemented (S49). Accordingly, the initial value V2ini of the target secondary voltage V2tgt is a value that is lowered by the correction value α from the normal initial value V2ini.

  When the vehicle speed V becomes equal to or higher than the threshold value THV4 at time t2, the ECU 24 cancels the power generation suppression of the FC32. That is, until then, the motor 14 was driven by the power of the battery 20, but the motor 14 is also driven using the FC power Pfc. Along with this, the target FC current Ifctgt calculated by the ECU 24 gradually increases. However, since rate limit control is performed, the slope of the increase is constant in both the present embodiment and the comparative example. Further, as described above, the inclination of the present embodiment is larger than that of the comparative example.

  Furthermore, in this embodiment, the target secondary voltage V2tgt immediately becomes equal to or lower than OCV at the time t2 when the suppression is released, and the FC current Ifc increases. On the other hand, in the comparative example, the FC current Ifc does not increase at the time point t2 because the target secondary voltage V2tgt is greater than the OCV. After time t3, the target secondary voltage V2tgt is equal to or lower than OCV in the comparative example, and the FC current Ifc increases.

4). As described above, according to this embodiment, the high load condition (S47: YES, S48: YES in FIG. 8) and the suppression release condition (V4> THV4) are satisfied while the power generation of the FC 32 is suppressed. In this case, the amount of change in the target FC current Ifctgt is increased immediately after cancellation of power generation suppression, compared to when the suppression cancellation condition is satisfied without the high load condition being satisfied (S74 in FIG. 10). Thereby, when canceling the power generation suppression of the FC 32, if a high load is required, it becomes possible to ensure suitable drivability. Further, when canceling the power generation suppression of the FC32, if a high load is not required, the target FC current Ifctgt is not increased immediately after the cancellation of the power generation suppression (in order to use step S78 as a normal control), and thus excellent fuel efficiency is achieved. Can be maintained.

  In the present embodiment, the target rotational speed Naptgt of the air pump 36 and the target opening degree θvtgt of the back pressure valve 60 are made to follow the target FC current Ifctgt, and a high load condition (S47 in FIG. 8) is performed during power generation suppression by the ECU 24 (power generation suppression function 122). : YES, S48: YES) and when the suppression release condition (V4> THV4) is satisfied, the ECU 24 (return rising speed changing function 126) indicates that the high load condition is not satisfied and the suppression release condition is satisfied. In comparison, the rotational speed Nap of the air pump 36 and the opening degree θv of the back pressure valve 60 are increased by setting the target FC current Ifctgt high. Thereby, when canceling the power generation suppression of the FC 32, it is possible to prevent the shortage of the reaction gas even when a high load is required, and it is possible to suppress the deterioration of the FC 32 due to the shortage of the reaction gas. Moreover, when canceling the power generation suppression of the FC 32, drivability can be more reliably maintained by suppressing the shortage of reaction gas when a high load is required.

  In the present embodiment, when the high load condition (S47: YES, S48: YES in FIG. 8) and the suppression release condition (V4> THV4) are satisfied during power generation suppression by the ECU 24 (power generation suppression function 122), the ECU 24 (return rising) The speed changing function 126) increases the change speed of the FC voltage Vfc by increasing the FB gain Gfb of the DC / DC converter 22 as compared with the case where the suppression release condition is satisfied without the high load condition being satisfied. To do. As a result, when canceling the power generation suppression of the FC 32, even if a high load is required, it is possible to draw a good current from the FC 32 by quickly changing the FC voltage Vfc. As a result, even immediately after canceling power generation suppression, the FC power Pfc can be made to follow the required load quickly, so that drivability can be further improved.

  In the present embodiment, when the high load condition (S47: YES, S48: YES in FIG. 8) and the suppression release condition (V4> THV4) are satisfied during power generation suppression by the ECU 24 (power generation suppression function 122), the ECU 24 (return rising) The speed changing function 126) lowers the initial value V2ini of the target secondary voltage V2tgt after the power generation suppression cancellation compared to the case where the suppression cancellation condition is satisfied without the high load condition being satisfied (S73 in FIG. 10). ).

  Due to the characteristics of FC32, the FC current Ifc and the FC power Pfc can be increased when the FC voltage Vfc is lower. The DC / DC converter 22 controls the FC voltage Vfc by adjusting the secondary voltage V2. According to the present embodiment, when canceling the power generation suppression of the FC 32, if a high load is required, the FC power Pfc can be quickly increased by lowering the initial value V2ini of the converter output voltage (secondary voltage V2). It can be increased. As a result, even immediately after canceling power generation suppression, the FC power Pfc can be made to follow the required load quickly, so that drivability can be further improved.

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

[5-1. Applicable to]
In the said embodiment, although the example which applied the power supply system 12 to the FC vehicle 10 was shown, not only this but the power supply system 12 may be applied to another object. For example, the present invention can also be applied to a mobile body such as an electric assist bicycle, a ship, and an aircraft.

[5-2. Configuration of power supply system 12]
In the above embodiment, the FC 32 and the battery 20 are arranged in parallel, and the DC / DC converter 22 is arranged in front of the battery 20, but the present invention is not limited to this. For example, as shown in FIG. 17, the FC 32 and the battery 20 may be arranged in parallel, and the step-up, step-down or step-up / step-down DC / DC converter 150 may be arranged in front of the FC 32. Alternatively, as shown in FIG. 18, the FC 32 and the battery 20 may be arranged in parallel, and the DC / DC converter 150 may be arranged in front of the FC 32 and the DC / DC converter 22 may be arranged in front of the battery 20. Alternatively, as shown in FIG. 19, the FC 32 and the battery 20 may be arranged in series, and the DC / DC converter 22 may be arranged between the battery 20 and the motor 14.

[5-3. Power generation mode]
(5-3-1. Power generation suspension mode)
In the above embodiment, the power generation suspension mode in which the target FC current Ifctgt is zero is used. However, the mode is not limited to this as long as it is a mode for suppressing the power generation of the FC 32 (a mode for suppressing the target FC current Ifctgt). For example, a value greater than zero may be set as the target FC current Ifctgt.

(5-3-2. Conditions for switching from normal power generation mode to power generation halt mode)
In the above embodiment, the condition that the vehicle speed V is equal to or lower than the first voltage threshold value THV1 (S23 in FIG. 6: YES) is used as a condition for switching from the normal power generation mode to the power generation suspension mode. For example, the normal power generation mode may be switched to the power generation suspension mode when the accelerator opening θ is equal to or less than a threshold value indicating that the operation of the accelerator pedal 116 is not performed.

(5-3-3. Conditions for returning from the power generation halt mode to the normal power generation mode)
In the above embodiment, the vehicle speed V is equal to or higher than the second voltage threshold value THV2 (S25 in FIG. 6: YES) as a condition for switching from the power generation halt mode to the normal power generation mode (suppression cancellation condition). Absent. For example, the power generation suspension mode may be switched to the normal power generation mode when the accelerator opening θ is equal to or greater than a threshold value indicating that the accelerator pedal 116 is being operated.

(5-3-4. Change method of return rising speed)
In the above embodiment, whether or not countermeasures for drivability deterioration need to be implemented is determined based on the determination time, the vehicle speed V, and the accelerator opening θ, but may be a scene where an increase in the system load Ls is sought after the power generation suspension mode ends. For example, it is not limited to this. For example, only one of the vehicle speed V and the accelerator opening degree θ may be used. Alternatively, instead of the vehicle speed V, a change amount [km / h / s] per unit time of the vehicle speed V may be used. Or you may use the variation | change_quantity per unit time of system load Ls itself or system load Ls.

  In the above embodiment, as a countermeasure against the deterioration of drivability, the power generation suspension mode is set by increasing the allowable maximum change amount of the target FC current Ifctgt (and the corresponding target secondary voltage V2tgt) and increasing the feedback gain Gfb. However, the present invention is not limited to this as long as the allowable maximum change amount of the FC power Pfc is increased. For example, increasing the allowable maximum change amount of the target FC current Ifctgt (and the target secondary voltage V2tgt) and increasing the feedback gain Gfb increase the return rising speed from the power generation halt mode to the normal power generation mode. May be. Alternatively, the feed forward gain used for the FF term of the DC / DC converter 22 may be increased. Alternatively, at least one of the target rotational speed Naptgt of the air pump 36 and the target opening degree θvtgt of the back pressure valve 60 may be increased.

(5-3-5. Others)
In the above embodiment, the end of the power generation suspension mode (switching to the normal power generation mode) and the cancellation of power generation suppression are performed at different timings, but both may be performed at the same timing.

  In the above embodiment, the target secondary voltage V2tgt in the power generation halt mode is set to a value higher than the OCV. However, the present invention is not limited to this, and the target secondary voltage V2tgt may be set to a value equal to or less than the OCV. Good.

[5-4. Others]
In the above-described embodiment, the configuration including the air pump 36 that supplies air containing oxygen is illustrated. However, instead of or in addition to this, a configuration including a hydrogen pump that supplies hydrogen may be employed.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell vehicle 14 ... Traveling motor 18 ... Fuel cell unit (reaction gas supply means)
DESCRIPTION OF SYMBOLS 20 ... Battery (electric storage apparatus) 22 ... DC / DC converter 24 ... ECU 32 ... Fuel cell stack 122 ... Power generation suppression function (power generation suppression means) 124 ... Suppression release function (suppression release means)
126 ... Return rising speed changing function (return rising speed changing means)

Claims (4)

A traveling motor;
A fuel cell for supplying power to the travel motor;
A power storage device that supplies power to the travel motor and charges regenerative power from the travel motor;
A converter that is provided on the power storage device side and controls the output voltage of the fuel cell by transforming the output voltage of the power storage device;
Reactive gas supply means for supplying a reactive gas to the fuel cell;
Power generation suppression means for reducing the output of the fuel cell and the operating amount of the reaction gas supply means to a power generation suppression region lower than a normal operation region when a power generation suppression condition for suppressing power generation of the fuel cell is established;
Suppression release means for returning the output of the fuel cell and the operating amount of the reaction gas supply means to the normal operation region when a suppression release condition for releasing power generation suppression of the fuel cell is satisfied;
When the predetermined high load condition and the suppression release condition are satisfied during power generation suppression by the power generation suppression means, the power generation suppression is compared with the case where the suppression release condition is satisfied without the high load condition being satisfied. A return rise speed changing means for increasing at least one change amount of the reactant gas supplied to the fuel cell and the output current and output voltage of the fuel cell immediately after release of the fuel cell vehicle. The fuel cell vehicle according to claim 1, wherein
The operating amount of the reaction gas supply means follows the target output of the fuel cell,
When the high load condition and the suppression release condition are satisfied during power generation suppression by the power generation suppression unit, the return rising speed changing unit is compared with the case where the suppression release condition is satisfied without the high load condition being satisfied. Thus, by setting the target output of the fuel cell high, the operating amount of the reaction gas supply means and the amount of change in the supply amount of the reaction gas are increased. The fuel cell vehicle according to claim 1 or 2,
When the high load condition and the suppression release condition are satisfied during power generation suppression by the power generation suppression unit, the return rising speed changing unit is compared with the case where the suppression release condition is satisfied without the high load condition being satisfied. Thus, the rate of change in the output voltage of the fuel cell is increased by increasing the feedback gain of the converter. The fuel cell vehicle according to any one of claims 1 to 3,
When the high load condition and the suppression release condition are satisfied during power generation suppression by the power generation suppression unit, the return rising speed changing unit is compared with the case where the suppression release condition is satisfied without the high load condition being satisfied. And reducing the initial output voltage of the converter after the cancellation of power generation suppression.

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