JP4712895B2 - Fuel cell vehicle - Google Patents

Description

  The present invention relates to a fuel cell vehicle in which an output voltage of a fuel cell is boosted by a DC / DC converter and supplied to a traveling motor. More specifically, the present invention relates to a fuel cell vehicle capable of realizing power saving and downsizing of the DC / DC converter.

  A fuel cell vehicle that obtains driving force by supplying electric power from a fuel cell to a traveling motor is known. Some of such fuel cell vehicles boost the output voltage of the fuel cell with a DC / DC converter and supply it to a traveling motor (Patent Documents 1 and 2). The fuel cell vehicles of Patent Documents 1 and 2 include a power storage device in addition to the fuel cell, and drive the traveling motor by combining the power from the fuel cell and the power from the power storage device.

JP 2005-348530 A JP 2007-318938 A

  Although the DC / DC converters described in Patent Documents 1 and 2 are effective in controlling the output voltage of the fuel cell, there is still room for improvement in terms of power saving and miniaturization.

  The present invention has been made in consideration of such problems, and provides a fuel cell vehicle capable of realizing power saving and downsizing of a DC / DC converter that boosts the output voltage of the fuel cell with respect to the traveling motor. The purpose is to provide.

  The fuel cell vehicle according to the present invention includes a travel motor, a fuel cell, a DC / DC converter that boosts an output voltage of the fuel cell and supplies the travel motor to the travel motor, and a control that controls power supply to the travel motor. The output voltage of the fuel cell exceeds the required voltage of the traveling motor during steady traveling when the traveling motor operates below a continuous rated output, and the traveling motor outputs the continuous rated output. Is set to be lower than the required voltage of the travel motor during unsteady travel that operates above the control, and when the control device determines that the output voltage of the fuel cell is lower than the required voltage of the travel motor, The DC / DC converter is caused to perform a boosting operation.

  According to the present invention, the DC / DC converter performs a boosting operation during non-steady running and does not perform a boosting operation during steady running. Thereby, the DC / DC converter does not need to perform step-up during steady running and can realize power saving. In addition, as a specification of the DC / DC converter, it is almost unnecessary to consider the continuous rating, and only the time rating needs to be considered. As a result, the DC / DC converter can be downsized.

  In the above, it may further include a bypass diode that bypasses the DC / DC converter and supplies power from the fuel cell to the traveling motor.

  The fuel cell vehicle further includes a power storage device and a second DC / DC converter disposed between the travel motor and the power storage device, and the control device is configured to perform the steady travel and the unsteady travel. In either case, voltage target value control for the second DC / DC converter may be performed, and different voltage target values may be used during the steady running and during the unsteady running.

  In this case, the control device calculates a target current of the fuel cell, calculates a target voltage of the fuel cell from the target current, and uses the target voltage of the fuel cell as the voltage target value during the steady running. During the unsteady running, it is preferable to use the required voltage of the running motor as the voltage target value.

  Instead of the above, the control device may perform current target value control for the second DC / DC converter during the steady running, and may perform voltage target value control for the second DC / DC converter during the non-steady running. it can.

  In this case, the control device calculates the target current of the fuel cell, uses the target current of the fuel cell as the current target value during the steady running, and uses the required voltage of the running motor during the non-steady running. It is preferable to use it as the voltage target value.

  Moreover, it is preferable that the fuel cell vehicle includes a storage unit that stores a required output of the travel motor and a required voltage in a mapped manner.

  The control device may compare a target voltage of the fuel cell with a necessary voltage of the travel motor, and determine the steady travel time and the unsteady travel time based on the comparison result.

  The continuous rated output is a steady guaranteed output as an output of the traveling motor required when climbing a target gradient at a target vehicle speed that is a vehicle power performance target value, and the steady running is an output that is equal to or less than the steady guaranteed output. It is a travel motor drive state in which a motor is operated, and the unsteady travel is preferably a travel motor drive state in which the travel motor is operated with an output exceeding the steady guaranteed output.

  According to the present invention, the DC / DC converter performs a boosting operation during non-steady running and does not perform a boosting operation during steady running. Thereby, the DC / DC converter does not need to perform step-up during steady running and can realize power saving. In addition, as a specification of the DC / DC converter, it is almost unnecessary to consider the continuous rating, and only the time rating needs to be considered. As a result, the DC / DC converter can be downsized.

1 is a circuit diagram of a fuel cell vehicle according to a first embodiment of the present invention. It is a flowchart of the process in the integrated control part of 1st Embodiment. It is explanatory drawing of the characteristic of the motor required voltage in 1st Embodiment, the characteristic of the electric power generation voltage of a fuel cell, and the characteristic of PDU target voltage. It is explanatory drawing of the current-voltage characteristic of a fuel cell. It is explanatory drawing which shows the method of determining a continuous rated output. It is a flowchart of the process in the 1st converter control part of 1st Embodiment. It is a flowchart of the process in the 2nd converter control part of 1st Embodiment. It is explanatory drawing of the characteristic of the motor required voltage in a comparative example, the characteristic of the electric power generation voltage of a fuel cell, and the characteristic of PDU target voltage. FIG. 4 is a circuit diagram of a fuel cell vehicle according to a second embodiment of the present invention. It is a flowchart of the process in the integrated control part of 2nd Embodiment.

  Hereinafter, fuel cell vehicles according to a plurality of embodiments of the present invention will be described with reference to the drawings.

A. First Embodiment 1. FIG. Configuration of Fuel Cell Vehicle 10 (1) Overall Configuration FIG. 1 is a circuit diagram of a fuel cell vehicle 10 (hereinafter also referred to as “FC vehicle 10”) according to the first embodiment. The FC vehicle 10 basically includes a motor unit 20, an FC unit 40, a battery unit 60, and an overall control unit 80.

  The motor unit 20 generates a travel driving force for the fuel cell vehicle 10 using the travel motor 22 when the FC vehicle 10 is powered, and when the FC vehicle 10 is regenerated, the regenerative power generated by the motor 22 (motor regenerative power). Preg) [W] is supplied to the battery unit 60.

  The FC unit 40 supplies generated power (FC generated power Pfc) [W] generated by a fuel cell 42 (hereinafter also referred to as “FC42”) to the motor unit 20 when the FC vehicle 10 is powered. During regeneration of the vehicle 10, the FC generated power Pfc is supplied to the battery unit 60.

  When the FC vehicle 10 is powered, the battery unit 60 supplies output power (battery output power Pbat) [W] from the power storage device 62 (hereinafter also referred to as “battery 62”), which is energy storage, to the motor unit 20. When the FC vehicle 10 is regenerated, the motor regenerative power Preg and the FC generated power Pfc are stored in the battery 62.

  The overall control unit 80 controls the motor unit 20, the FC unit 40, and the battery unit 60. Details will be described later.

  The motor regenerative power Preg, the FC generated power Pfc, and the battery output power Pbat may be supplied to auxiliary equipment (not shown) such as a light, a power window, and a wiper motor.

(2) Motor unit 20
In addition to the motor 22, the motor unit 20 includes a power drive unit 24 (hereinafter also referred to as “PDU24”), a speed reducer 26, a shaft 28, a wheel 30, and a motor control unit 32.

  The PDU 24 converts the generated current (FC generated current If) [A] from the FC 42 and the output current (battery output current Ibat) [A] from the battery 62 when the FC vehicle 10 is powered, Is supplied to the motor 22 as a current for driving the motor 22 (motor driving current Imd) [A]. The rotation of the motor 22 accompanying the supply of the motor drive current Imd is transmitted to the wheels 30 through the speed reducer 26 and the shaft 28.

  In addition, the PDU 24 performs AC / DC conversion on the regenerative current (motor regenerative current Imr) from the motor 22 when the FC vehicle 10 is regenerated, and supplies the battery unit 60 with the battery charging current Ibc. The battery 62 is charged by the supply of the battery charging current Ibc.

  The motor control unit 32 controls the operation of the motor 22 and the PDU 24.

(3) FC unit 40
In addition to the FC 42, the FC unit 40 includes a hydrogen tank 44, an air compressor 46, an FC control unit 48, a first DC / DC converter 50, a first converter control unit 52, a bypass diode 54, and a disconnect diode 56. And a current sensor 58.

  The FC 42 has, for example, a stack structure in which cells formed by sandwiching a solid polymer electrolyte membrane between an anode electrode and a cathode electrode from both sides are stacked. A hydrogen tank 44 and an air compressor 46 are connected to the FC 42 by piping. Pressurized hydrogen in the hydrogen tank 44 is supplied to the anode electrode of the FC 42. Further, air is supplied to the cathode electrode of the FC 42 by the air compressor 46. The operations of the hydrogen tank 44 and the air compressor 46 are controlled by the FC control unit 48. An FC power generation current If is generated by an electrochemical reaction between hydrogen (fuel gas), which is a reaction gas, and air (oxidant gas) in the FC 42. The FC power generation current If is supplied to the PDU 24 when the FC vehicle 10 is powered through the current sensor 58, the first DC / DC converter 50, the bypass diode 54, and the disconnect diode 56, and is supplied to the battery unit 60 during regeneration. The first DC / DC converter 50 is a so-called chopper type step-up DC / DC converter. When the FC power generation current If passes through the first DC / DC converter 50, the first DC / DC converter 50 boosts the power generation voltage (FC power generation voltage Vf) [V] of the FC 42. The operation of the first DC / DC converter 50 is controlled by the first converter control unit 52 based on a command from the overall control unit 80 and a detection value of the current sensor 58.

(4) Battery unit 60
In addition to the battery 62, the battery unit 60 includes voltage sensors 64 and 66, current sensors 68 and 70, a second DC / DC converter 72, and a second converter control unit 74.

  The battery 62 is connected to the primary side 1S of the second DC / DC converter 72. For example, a lithium ion secondary battery, a nickel hydride secondary battery, or a capacitor can be used. In the first embodiment, a lithium ion secondary battery is used. The voltage sensor 64 detects the voltage (primary voltage V1) [V] of the primary side 1S of the second DC / DC converter 72, and the voltage sensor 66 detects the voltage of the secondary side 2S of the second DC / DC converter 72 ( Secondary voltage V2) [V] is detected. The current sensor 70 detects the primary side 1S current (primary current I1), and the current sensor 70 detects the secondary side 2S current (secondary current I2).

  The second DC / DC converter 72 is a so-called chopper step-up / step-down DC / DC converter, which boosts the primary voltage V1 and supplies it to the secondary side 2S during power running, and steps down the secondary voltage V2 during regeneration. To the primary side 1S. That is, the regenerative voltage (motor regenerative voltage Vreg) [V] generated by the motor 22 or the secondary voltage V2 that is the FC power generation voltage Vf of the FC 42 is converted into a low voltage by the second DC / DC converter 72. The battery 62 is charged.

  The second converter control unit 74 controls the second DC / DC converter 72 based on the command from the overall control unit 80 and the detection values of the voltage sensors 64 and 66 and the current sensors 68 and 70.

(5) General control unit 80
Based on the required output of the motor 22 (motor required output Pmr_req) [W], the required power of the FC unit 40 (air compressor 46, etc.), the required power of an auxiliary machine (not shown), The FC control unit 48, the first converter control unit 52, and the second converter control unit 74 are controlled. Details will be described later.

  In addition to the overall control unit 80, CPU, ROM, RAM, and timer, it has an input / output interface such as an A / D converter and a D / A converter, and a DSP (Digital Signal Processor) if necessary. . The same applies to the motor control unit 32, the FC control unit 48, the first converter control unit 52, and the second converter control unit 74.

  The overall control unit 80, the motor control unit 32, the FC control unit 48, the first converter control unit 52, and the second converter control unit 74 are mutually connected through a communication line 82 such as a CAN (Controller Area Network) that is an in-vehicle LAN. It is connected. These control units share input / output information from various switches and various sensors, and each CPU executes various programs by executing programs stored in each ROM with input / output information from these various switches and various sensors as inputs. Realize the function.

(6) Others As various switches and various sensors for detecting the vehicle state, in addition to the voltage sensors 64 and 66 and the current sensors 58, 68 and 70 described above, an ignition switch 84 connected to the communication line 82, an accelerator sensor 86, There are a brake sensor 88, a vehicle speed sensor 90, and the like.

2. Various Control / Processing (1) Processing in Overall Control Unit 80 FIG. 2 shows a flowchart for calculating the control target value used in the first DC / DC converter 50 and the second DC / DC converter 72 in the overall control unit 80. .

  In step S <b> 1, the overall control unit 80 calculates a motor request output Pmr_req in accordance with an accelerator pedal depression amount (not shown) notified from the accelerator sensor 86.

  In subsequent step S <b> 2, the overall control unit 80 calculates the required voltage of the motor 22 (motor required voltage Vmr_nec) [V] from the motor request output Pmr_req. In calculating the required motor voltage Vmr_nec, the relationship (mapped data) between the required motor output Pmr_req and the required motor voltage Vmr_nec stored in the memory 81 of the overall control unit 80 is used.

  As shown in FIG. 3, the characteristic 100 (represented by a dotted line in FIG. 3) of the necessary motor voltage Vmr_nec is a linear function of the motor required output Pmr_req. Further, the FC 42 of the first embodiment has a characteristic (IV characteristic 102) in which the FC power generation voltage Vf decreases as the FC power generation current If increases, as in a general fuel cell (see FIG. 4). For this reason, the characteristic 104 of the FC power generation voltage Vf represented by the alternate long and short dash line in FIG. 3 decreases as the output of the motor 22 (motor output Pmr) [W] increases. In the first embodiment, the specifications of the motor 22 and the FC 42 are set so that the motor output P2 at which the characteristic 100 of the necessary motor voltage Vmr_nec intersects the characteristic 104 of the FC power generation voltage Vf becomes the continuous rated output Pcr of the motor 22. It is determined. Hereinafter, a state where the motor output Pmr is equal to or less than the continuous rated output Pcr is referred to as a “steady running state”, and a state exceeding the continuous rated output Pcr is referred to as an “unsteady running state”.

  FIG. 5 shows an explanatory diagram of a method for determining the continuous rated output Pcr. The continuous rated output Pcr of the first embodiment is a steady guaranteed output Pcg [W] as a motor output Pmr necessary for climbing a target gradient at a target vehicle speed Vtar [km / h] that is a vehicle power target value. For this reason, the steady running state is a running motor driving state in which the motor 22 is driven with an output equal to or lower than the steady guaranteed output Pcg, and the unsteady running state is a running motor drive for driving the motor 22 with an output exceeding the steady guaranteed output Pcg. State.

  Returning to FIG. 3, the characteristic 106 (represented by a solid line in FIG. 3) of the target voltage (PDU target voltage Vp_tar) [V] of the PDU 24 is set according to the motor required output Pmr_req {Vp_tar = f (Pmr_req)}. When the motor request output Pmr_req is zero, the PDU target voltage Vp_tar is set to be lower than the FC power generation voltage Vf.

  Further, the motor output P2 (the motor output Pmr where the characteristic 106 of the PDU target voltage Vp_tar and the characteristic 104 of the FC power generation voltage Vf are in contact with each other), the motor output P2 (the characteristic 100 of the necessary motor voltage Vmr_nec, and the characteristic 104 of the FC power generation voltage Vf) Is less than the motor output Pmr that intersects, that is, the continuous rated output Pcr), the characteristic 106 of the PDU target voltage Vp_tar decreases as the motor required output Pmr_req increases. For example, the characteristic 106 of the PDU target voltage Vp_tar is the same as the characteristic 104 of the FC power generation voltage Vf between the motor outputs P1 and P2.

  Furthermore, when the motor required output Pmr_req is larger than the motor output P2 (continuous rated output Pcr), the characteristic 106 of the PDU target voltage Vp_tar becomes equal to the characteristic 100 of the motor required voltage Vmr_nec. In FIG. 3, a characteristic 108 indicated by a two-dot chain line between the motor outputs P1 to P3 is a characteristic of a PDU target voltage Vp_tar_c of a comparative example described later.

  Returning to FIG. 2, in step S3, the overall control unit 80 determines the target current (FC) of the FC 42 based on the motor required output Pmr_req, the required power of the FC unit 40 (air compressor 46, etc.), and the required power of an auxiliary machine (not shown). Target current If_tar) [A] is calculated. The calculated FC target current If_tar is notified to the FC control unit 48. The FC controller 48 that has received the FC target current If_tar, based on an error ΔIf1 (ΔIf1 = If_tar−If) between the FC target current If_tar and the FC power generation current If detected by the current sensor 58, the FC 42, the hydrogen tank 44, and the like. And the air compressor 46 is controlled.

  In subsequent step S4, the overall control unit 80 calculates the target voltage (FC target voltage Vf_tar) of the FC 42 using the IV characteristic 102 (FIG. 4) of the FC 42. The IV characteristic 102 is mapped and stored in the memory 81 of the overall control unit 80. Further, the FC target current If_tar is calculated not only based on the motor required output Pmr_req but also in consideration of the required power of the FC unit 40 and the required power of the auxiliary machine. Therefore, it should be noted that the position of the motor required voltage Vmr_nec and the position of the FC target voltage Vf_tar on the horizontal axis in FIG. 3 may be different.

  In step S5, the overall control unit 80 determines whether or not the FC vehicle 10 is in a steady running state. Specifically, it is determined whether or not the FC target voltage Vf_tar calculated in step S4 is equal to or higher than the motor required voltage Vmr_nec calculated in step S2. As described above, the characteristic 100 of the required motor voltage Vmr_nec and the characteristic 104 of the FC power generation voltage Vf intersect at the continuous rated output Pcr (motor output P2). Moreover, it is a steady running state when it is below the continuous rated output Pcr, and it is an unsteady running state when it exceeds the continuous rated output Pcr. For this reason, when the FC target voltage Vf_tar is equal to or higher than the motor required voltage Vmr_nec, the vehicle is in a steady running state, and when the FC target voltage Vf_tar is lower than the motor required voltage Vmr_nec, the vehicle is in an unsteady running state.

  When the FC vehicle 10 is in the steady running state (S5: Yes), in step S6, the overall control unit 80 sets the FC target voltage Vf_tar to the voltage target value after boosting the second DC / DC converter 72 (voltage target value V2con_tar). (V2con_tar ← Vf_tar), and notifies the second converter control unit 74 of this voltage target value V2con_tar. On the other hand, the boosted target value of the first DC / DC converter 50 is not calculated, and the first DC / DC converter 50 is not operated. Thereby, the FC power generation voltage Vf is supplied to the PDU 24 via the bypass diode 54 instead of the first DC / DC converter 50.

  When the FC vehicle 10 is in an unsteady traveling state (S5: No), in step S7, the overall control unit 80 sets the required motor voltage Vmr_nec calculated in step S2 as the voltage target value V2con_tar of the second DC / DC converter 72. (V2con_tar ← Vmr_nec), and notifies the second converter control unit 74 of the voltage target value V2con_tar. In subsequent step S8, the overall control unit 80 sets the FC target current If_tar obtained in step S3 as the fuel cell side current target value (current target value I1con_tar) of the first DC / DC converter 50 (I1con_tar ← If_tar). The current target value I1con_tar is notified to the first converter control unit 52.

(2) Processing in First Converter Control Unit 52 FIG. 6 shows a flowchart of processing performed by the first converter control unit 52. In step S11, the first converter control unit 52 determines whether or not the current target value I1con_tar of the first DC / DC converter 50 has been received. When the current target value I1con_tar has not been received (S11: No), the FC vehicle 10 is considered to be in a steady running state (a state equal to or lower than the continuous rated output Pcr in FIG. 3). Therefore, the first converter control unit 52 supplies the FC power generation current If to the PDU 24 via the bypass diode 54 without operating the first DC / DC converter 50 (without boosting the FC power generation voltage Vf).

  On the other hand, when the current target value I1con_tar is received (S11: Yes), the FC vehicle 10 is considered to be in an unsteady traveling state (a state exceeding the continuous rated output Pcr in FIG. 3). Therefore, in step S13, the first converter control unit 52 performs feedback control of the first DC / DC converter 50 using the current target value I1con_tar. Specifically, an error ΔIf2 (ΔIf2 = I1con_tar−If) between the current target value I1con_tar (= I1_tar) and the FC power generation current If detected by the current sensor 58 is calculated, and the FC power generation current If is the current target value I1con_tar. The drive duty is adjusted so as to be equal to, and the FC power generation voltage Vf is boosted. At this time, for example, proportional / integral / derivative control (PID control) can be used.

(3) Processing in Second Converter Control Unit 74 FIG. 7 shows a flowchart of processing performed by the second converter control unit 74. In step S21, the second converter control unit 74 receives the voltage target value V2con_tar of the second DC / DC converter 72 transmitted in step S6 or step S7 of FIG. In subsequent step S <b> 22, second converter control unit 74 controls second DC / DC converter 72 using voltage target value V <b> 2 con_tar. Specifically, the duty DUT defined by the following formulas (1) to (7) is calculated, and the switching is performed by driving a switching element (not shown) of the second DC / DC converter 72 using the duty DUT. Do.
DUT = FF term + FB term (1)
FF term = 1− (V1 / V2con_tar) (2)
FB term = P term + I term + D term (3)
P term = Kp × ΔV2 (4)
I term = I term last time + Ki × ΔV2 (5)
D term = Kd × (ΔV2−ΔV2 last time) (6)
ΔV2 = V2con_tar−V2 (7)

  The FF term in Equation (1) is a feedforward term, and the FB term is a feedback term. The P term, I term, and D term in Equation (3) are the proportional term, integral term, and differential term of proportional / integral / derivative control (PID control), respectively. The coefficients Kp, Ki, and Kd in the equations (4) to (6) are a proportional coefficient, an integral coefficient, and a differential coefficient, respectively.

(4) Comparative Example FIG. 8 shows a comparative example for comparison with each characteristic of the first embodiment shown in FIG. This comparative example is based on, for example, FIG. In FIG. 8, the characteristic 100 of the necessary motor voltage Vmr_nec and the characteristic 104 of the FC power generation voltage Vf are the same as those in FIG. On the other hand, the continuous rated output Pcr in FIG. 3 is set to the motor output P2 where the characteristic 100 of the motor required voltage Vmr_nec and the characteristic 104 of the FC power generation voltage Vf intersect (Pcr = P2), whereas the continuous rated output Pcr in FIG. The rated output Pcr is set to a value larger than the motor output P2 (Pcr> P2).

  Further, the PDU target voltage Vp_tar_c in FIG. 8 is a characteristic that increases as the motor output Pmr increases. Therefore, the PDU target voltage Vp_tar in FIG. 3 is different from the PDU target voltage Vp_tar_c of the comparative example in the following points.

  That is, in the PDU target voltage Vp_tar_c of the comparative example (FIG. 8), the PDU target voltage Vp_tar increases from Vp_p1 to Vp_p2 ′ while the motor output Pmr is between P1 and P2, and the PDU target voltage Vp_tar exceeds the FC power generation voltage Vf. . For this reason, it is necessary to boost the FC power generation voltage Vf in the comparative example while the motor output Pmr is between P1 and P2.

  On the other hand, in the PDU target voltage Vp_tar of the first embodiment (FIG. 3), the PDU target voltage Vp_tar decreases from Vp_p1 to Vp_p2 while the motor output Pmr is between P1 and P2. In other words, the characteristic 106 of the PDU target voltage Vp_tar from the PDU target voltage Vp_p1 when the motor output Pmr is P1 to the PDU target voltage Vp_p2 when the motor output Pmr is P2 is the characteristic 104 of the FC power generation voltage Vf. Decreases equally. This eliminates the need for boosting by the first DC / DC converter 50 while the motor output Pmr is between P1 and P2.

  Further, in the comparative example (FIG. 8), the characteristic 108 of the PDU target voltage Vp_tar_c exceeds the characteristic 100 of the necessary motor voltage Vmr_nec while the motor output Pmr is between P2 and P3. The motor output P3 is a motor output Pmr at which the PDU target voltage Vp_tar_c of the comparative example intersects the motor required voltage Vmr_nec. For this reason, in the comparative example, it is necessary to boost the FC power generation voltage Vf so that it exceeds the motor required voltage Vmr_nec while the motor output Pmr is between P2 and P3.

  On the other hand, the PDU target voltage Vp_tar of the first embodiment (FIG. 3) has the same characteristics as the required motor voltage Vmr_nec when the motor output Pmr is P2 to P3. Thereby, compared with the PDU target voltage Vp_tar_c of the comparative example, the PDU target voltage Vp_tar of the first embodiment can be brought close to the required motor voltage Vmr_nec while the motor output Pmr is between P2 and P3. Extra boosting by the DC converter 50 can be avoided.

3. Effects of First Embodiment As described above, in the first embodiment, the first DC / DC converter 50 performs a boost operation during non-steady travel and does not perform a boost operation during steady travel. As a result, the first DC / DC converter 50 does not need to increase the voltage during steady running, and can realize power saving. In addition, as the specification of the first DC / DC converter 50, it is almost unnecessary to consider the continuous rating, and only the time rating needs to be considered. As a result, the first DC / DC converter 50 can be reduced in size.

  In the first embodiment, a bypass diode 54 that bypasses the first DC / DC converter 50 and supplies the FC generated power Pfc from the FC 42 to the motor 22 is provided. As a result, when the first DC / DC converter 50 does not perform the step-up operation, it is possible to supply power from the FC 42 to the motor 22 without going through the first DC / DC converter 50, and the internal resistance of the first DC / DC converter 50. Power consumption due to can be prevented.

  The second converter control unit 74 of the first embodiment performs voltage target value control for the second DC / DC converter 72 during both steady running and unsteady running, and during steady running and unsteady running. Different control target values (FC target voltage Vf_tar, motor required voltage Vmr_nec) are used. By using different voltage control target values for steady running and unsteady running, it is possible to control the operation of the second DC / DC converter 72 by distinguishing between steady running and unsteady running.

  Further, second converter control unit 74 uses FC target voltage Vf_tar as a voltage control target value during steady running, and uses motor required voltage Vmr_nec as a voltage control target value during non-steady running. Since control is performed with the FC target voltage Vf_tar as the voltage control target value during steady running, it is possible to consider the power generation efficiency of the FC 42 and during non-steady running, control is performed using the motor required voltage Vmr_nec as the voltage control target value. Therefore, the required motor voltage Vmr_nec can be reliably realized.

  In the first embodiment, the FC vehicle 10 includes a memory 81 of the overall control unit 80 that maps and stores the motor request output Pmr_req and the motor required voltage Vmr_nec. By mapping the motor request output Pmr_req and the required motor voltage Vmr_nec, the required motor voltage Vmr_nec can be quickly determined.

  In the first embodiment, the overall control unit 80 compares the FC target voltage Vf_tar and the necessary motor voltage Vmr_tar, and discriminates between steady running and unsteady running based on the comparison result. Since it is based on the comparison result between the FC target voltage Vf_tar and the required motor voltage Vmr_nec, it can be reliably determined whether the FC power generation voltage Vf is lower than the required motor voltage Vmr_nec.

B. Second Embodiment 1. FIG. FIG. 9 is a circuit diagram of a fuel cell vehicle 10A (hereinafter also referred to as “FC vehicle 10A”) according to the second embodiment. The FC vehicle 10A of the second embodiment is basically the same as the FC vehicle 10 of the first embodiment, but does not include the bypass diode 54, unlike the first embodiment. Instead, in the FC vehicle 10A, the duty DUT of a switching element (not shown) of the first DC / DC converter 50 is set to 100%, and the FC 42 side and the PDU 24 side of the first DC / DC converter 50 are directly connected. Thereby, the FC power generation voltage Vf is supplied to the PDU 24 without going through the step-up operation of the first DC / DC converter 50.

  FIG. 10 shows a flowchart for calculating a control target value used in the first DC / DC converter 50 and the second DC / DC converter 72 in the overall control unit 80 of the FC vehicle 10A.

  Steps S31 to S35, S38, and S39 in FIG. 10 are the same as steps S1 to S5, S7, and S8 in FIG. In step S36, the overall control unit 80 does not calculate the boosted voltage target value V2con_tar as the control target value of the second DC / DC converter 72, but uses the fuel cell side current of the first DC / DC converter 50 as the second DC. / Current target value I2con_tar as a control target value of DC converter 72 is calculated. The target current value I2con_tar is transmitted to the second converter control unit 74. The second converter control unit 74 that has received the current target value I2con_tar calculates an error ΔIf3 (ΔIf3 = I2con_tar−If) between the current target value I2con_tar and the FC power generation current If detected by the current sensor 58, and calculates the error ΔIf3. The second DC / DC converter 72 is feedback controlled so as to be zero.

  In the subsequent step S37, a target duty DUT1con_tar of 100% is calculated as a control target value (control command) for the first DC / DC converter 50. The target duty DUT1con_tar of 100% is transmitted to the first DC / DC converter 50. The first converter control unit 52 that has received the 100% target duty DUT1con_tar continues to turn on the switching element (not shown) of the first DC / DC converter 50 and directly connects the FC 42 side and the PDU 24 side of the first DC / DC converter 50. . Thereby, the first DC / DC converter 50 supplies the FC power generation voltage Vf to the PDU 24 without performing the boosting operation.

2. Effects of Second Embodiment In addition to the effects described in the first embodiment or instead of the effects described in the first embodiment, the second embodiment has the following effects.

  That is, the second converter control unit 74 of the second embodiment performs current target value control for the second DC / DC converter 72 during steady running, and performs voltage target value control for the second DC / DC converter 72 during non-steady running. Do. As a result, the current target value control is performed during steady running, and the voltage target value control is performed during non-steady running, whereby the operation control of the second DC / DC converter 72 can be performed while distinguishing between steady running and unsteady running. Become.

  Further, second converter control unit 74 uses FC target current If_tar as a current target value during steady running, and uses motor required voltage Vmr_tar as a voltage target value during non-steady running. Since control is performed using the FC target current If_tar as a current target value during steady running, it is possible to consider the power generation efficiency of the FC 42, and during non-steady running, control is performed using the required motor voltage Vmr_nec as a voltage target value. Therefore, the required motor voltage Vmr_nec can be reliably realized.

C. Modifications It should be noted that the present invention is not limited to the above-described embodiments, 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.

  In each of the above embodiments, the battery 62 is provided in addition to the FC 42 as the power supply source. However, a configuration having only the FC 42 is also possible.

  In the above embodiment, the comparison result between the FC target voltage Vf_tar and the required motor voltage Vmr_nec is used to determine the steady running time and the non-steady running time. However, the present invention is not limited to this. For example, the FC generated voltage Vf The comparison result of the required motor voltage Vmr_nec can also be used.

  In each of the above embodiments, the motor request output Pmr_req and the motor required voltage Vmr_nec are mapped and stored, but the present invention is not limited to this. For example, the required motor voltage Vmr_nec may be calculated sequentially based on the motor request output Pmr_req.

  In each of the above embodiments, the processing is distributed to a plurality of control units (overall control unit 80, motor control unit 32, FC control unit 48, first converter control unit 52, second converter control unit 74). All processes may be performed together in the control unit (for example, the overall control unit 80).

DESCRIPTION OF SYMBOLS 10, 10A ... Fuel cell vehicle 22 ... Motor 42 ... Fuel cell 50 ... 1st DC / DC converter 52 ... 1st converter control part 54 ... Bypass diode 62 ... Battery (power storage device) 72 ... 2nd DC / DC converter 74 ... 2nd Converter control unit 80 ... overall control unit 81 ... memory If_tar ... FC target current Pcg ... steady guaranteed output Pcr ... continuous rated output Pmr_req ... motor required output Vf ... FC power generation voltage Vf_tar ... FC target voltage Vmr_nec ... motor required voltage Vtar ... target vehicle speed

Claims (6)

A travel motor, a fuel cell, a first DC / DC converter that boosts an output voltage of the fuel cell and supplies the travel motor to the travel motor, a power storage device, and the travel motor and the power storage device are disposed. A fuel cell vehicle comprising a second DC / DC converter and a control device for controlling power supply to the travel motor,
The output voltage of the fuel cell exceeds the required voltage of the traveling motor during steady traveling when the traveling motor operates below the continuous rated output, and during unsteady traveling when the traveling motor operates above the continuous rated output. , Set to be lower than the required voltage of the travel motor,
The controller is
When it is determined that the output voltage of the fuel cell is lower than the required voltage of the traveling motor, the first DC / DC converter is caused to perform a boosting operation ,
In both the steady running and the unsteady running, the voltage target value control for the second DC / DC converter is constantly performed,
A fuel cell vehicle using different voltage target values for the steady running and the unsteady running . The fuel cell vehicle according to claim 1, further comprising:
A fuel cell vehicle comprising a bypass diode that bypasses the first DC / DC converter and supplies electric power from the fuel cell to the traveling motor. The fuel cell vehicle according to claim 1 or 2 ,
The controller is
Calculating a target current of the fuel cell, calculating a target voltage of the fuel cell from the target current;
The fuel cell vehicle, wherein the target voltage of the fuel cell is used as the voltage target value during the steady running, and the required voltage of the running motor is used as the voltage target value during the non-steady running. The fuel cell vehicle according to any one of claims 1 to 3 , further comprising:
A fuel cell vehicle comprising: a storage unit that maps and stores a required output of the travel motor and a required voltage. In the fuel cell vehicle according to any one of claims 1 to 4 ,
The control device compares a target voltage of the fuel cell with a required voltage of the travel motor, and determines the steady travel time and the unsteady travel time based on the comparison result. Battery vehicle. The fuel cell vehicle according to any one of claims 1 to 5 ,
The continuous rated output is a steady guaranteed output as an output of the traveling motor required when climbing a target gradient at a target vehicle speed that is a vehicle power performance target value,
The steady running is a running motor driving state in which the running motor is driven with an output equal to or lower than the steady guaranteed output,
The unsteady travel is a travel motor drive state in which the travel motor is driven with an output exceeding the steady guaranteed output.

Images