JP2018139194A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system in which revolving speed of a turbine can be controlled, while suppressing pressure fluctuation of oxidant gas supplied to a fuel cell.SOLUTION: A fuel cell system 10 includes an electrically-driven compressor 31 for compressing oxidant gas, a turbo compressor 32 for compressing first compression gas, compressed by the electrically-driven compressor 31, and a connection flow path 34 connecting both compressors 31, 32 and through which the first compression gas flows. The fuel cell system 10 includes a turbine 43 rotating with exhaust gas discharged from a fuel cell stack 11, a coupling part 52 for coupling the impeller 32a of the turbo compressor 32 and the turbine 43, a change part 42 capable of changing the flow path cross sectional area of a discharge flow path 41, and a heat exchange device 60 performing heat exchange with the first compression gas flowing through the connection flow path 34.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell system.

  Patent Document 1 discloses an electric compressor and a turbo compressor that compress oxidant gas, a fuel cell to which oxidant gas compressed by both compressors is supplied, and a rotational force obtained from exhaust gas discharged from the fuel cell. A fuel cell system comprising a turbine for driving a turbo compressor is described. Patent Document 1 describes that an intermediate cooler is provided in a connection flow path connecting an electric compressor and a turbo compressor.

  In addition, the fuel cell systems described in Patent Documents 1 and 2 are configured to control the rotational speed of the turbine by changing the cross-sectional area of the flow path through which the exhaust gas blown to the turbine flows.

JP 2005-507136 A JP 2000-315510 A

  According to the fuel cell systems described in Patent Documents 1 and 2 above, the efficiency of the turbine can be improved by controlling the rotational speed of the turbine through the change of the flow passage cross-sectional area of the flow passage through which the exhaust gas flows. However, when the flow path cross-sectional area is changed in this way, the amount of exhaust gas discharged from the fuel cell changes, and the pressure of the oxidant gas supplied to the fuel cell varies. As a result, a situation may occur in which the power generation amount of the fuel cell depending on the pressure of the oxidant gas supplied to the fuel cell cannot be set to a desired amount.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a fuel cell system capable of controlling the rotational speed of a turbine while suppressing fluctuations in the pressure of an oxidant gas supplied to the fuel cell. That is.

  A fuel cell system that achieves the above object includes an electric compressor that compresses an oxidant gas, a turbo compressor that compresses a first compressed gas that is the oxidant gas compressed by the electric compressor, and has an impeller. A connecting flow for connecting the fuel cell to which the second compressed gas, which is the oxidant gas compressed by the turbo compressor, is supplied, the electric compressor and the turbo compressor, and through which the first compressed gas flows. And a turbine that is rotated by the exhaust gas, the impeller of the turbo compressor, and the turbine are connected to the fuel cell through a passage and a discharge passage through which exhaust gas discharged from the fuel cell flows And a connecting portion for connecting the impeller and the turbine so as to rotate integrally with each other, Required in the fuel cell, a change unit that is provided in the discharge channel and changes the channel cross-sectional area of the discharge channel, a heat exchange device that exchanges heat with the first compressed gas flowing in the connection channel, and A grasping unit that grasps a required power generation amount that is a generated power amount and a temperature of the fuel cell, a required power generation amount and a temperature of the fuel cell that are grasped by the grasping unit, and an efficiency of the turbine A derivation unit for deriving a target temperature that is a target value for a turbo intake temperature that is a temperature of the first compressed gas after heat exchange with the heat exchange device; and the turbo intake temperature is the target temperature And a control unit that controls the heat exchange device.

  According to this configuration, the oxidant gas is compressed by the electric compressor and the turbo compressor. Thereby, compared with the case of only an electric compressor, the pressure ratio of the electric compressor required with respect to the required power generation amount can be reduced. Therefore, the power consumption of the electric compressor can be reduced. Moreover, since the turbo compressor is driven using the rotational force of the turbine, a dedicated electric motor or the like is not required separately as a drive source.

  Here, the inventors of the present application have found that the rotational speed of the turbine changes as the turbo intake temperature changes. Based on this knowledge, according to this configuration, the target derived by using the heat exchange device and determining the turbo intake temperature based on the required power generation amount, the fuel cell temperature, and the turbine efficiency which are grasped by the grasping unit. The temperature can be controlled. Thereby, the rotational speed of the turbine becomes the rotational speed corresponding to the target temperature. Accordingly, the rotational speed of the turbine can be set to a target value, for example, a value at which the efficiency of the turbine is relatively high, while suppressing fluctuations in the pressure of the oxidant gas supplied to the fuel cell.

  With respect to the fuel cell system, the supply flow rate and supply pressure, which are the flow rate and pressure of the second compressed gas supplied to the fuel cell, are determined by the required power generation amount and the temperature of the fuel cell that are grasped by the grasping unit. Assuming that the turbine rotational speed at which the turbine efficiency is maximized under the conditions of the corresponding target flow rate and target pressure is the target rotational speed, the target temperature is that the turbine rotational speed is the target rotational speed. It is good that it is the said turbo suction temperature.

  According to such a configuration, since the efficiency of the turbine can be maximized, the power consumption of the electric compressor can be reduced. As a result, the power consumption of the electric compressor can be further reduced while realizing the required power generation amount in the fuel cell.

  In the fuel cell system, the changing unit includes a variable nozzle and an actuator that drives the variable nozzle so that an opening degree of the variable nozzle changes, and the electric compressor compresses the oxidant gas. A compression unit to perform, and an electric motor that drives the compression unit, and the derivation unit is based on the required power generation amount and the temperature of the fuel cell that are grasped by the grasping unit, and the efficiency of the turbine In addition to derivation of the target temperature, a target opening degree corresponding to the target pressure and a target torque corresponding to the target flow rate are derived, and the control unit performs the variable in addition to the control of the heat exchange device The actuator is controlled so that the opening degree of the nozzle becomes the target opening degree, and the electric motor is controlled so that the torque of the electric motor becomes the target torque. The ratio of the target pressure to the pressure of the oxidant gas sucked into the electric compressor is a target pressure ratio, and the turbine is sucked into the electric compressor under the condition that the rotational speed of the turbine is the target rotational speed. When the specific pressure ratio is the pressure ratio of the electric compressor for the ratio of the supply pressure to the pressure of the oxidant gas to be the target pressure ratio, the target torque is the supply flow rate becomes the target flow rate, and The pressure ratio of the electric compressor may be set to a value that is the specific pressure ratio.

  The pressure ratio of the turbo compressor depends on the rotational speed of the turbine. For this reason, in a configuration in which the rotational speed of the turbine becomes the target rotational speed by controlling the turbo suction temperature to be the target temperature, the pressure ratio of the turbo compressor becomes a value corresponding to the target rotational speed. When the pressure ratio of the turbo compressor is determined, the specific pressure ratio is determined. In such a configuration, the target torque is set to a value at which the supply flow rate becomes the target flow rate and the pressure ratio of the electric compressor becomes the specific pressure ratio. Thereby, the efficiency of the turbine can be improved while the supply flow rate and the supply pressure are set to the target flow rate and the target pressure. Therefore, it is possible to reduce the power consumption of the electric compressor while generating the required power generation amount with the fuel cell.

  The fuel cell system includes a turbo intake temperature detection unit that detects the turbo intake temperature, and the control unit is configured so that the turbo intake temperature detected by the turbo intake temperature detection unit matches the target temperature. The heat exchange device may be controlled.

According to such a configuration, the turbo intake temperature can be directly grasped by the turbo intake temperature detection unit, so that the turbo intake temperature can be accurately controlled.
In particular, the fuel cell system employs a configuration in which the rotational speed of the turbine is controlled by controlling the turbo intake temperature. For this reason, in the control where the target temperature of the turbo intake temperature is not clearly defined, for example, the temperature of the first compressed gas flowing through the connection flow path is lowered within a possible range, the rotational speed of the turbine is appropriately controlled. The disadvantage of not being able to do so can occur. On the other hand, according to this configuration, as described above, the target temperature is derived by the deriving unit, and the turbo intake temperature detected by the turbo intake temperature detecting unit is controlled to become the target temperature. The rotation speed can be appropriately controlled, and the above inconvenience can be suppressed.

  In the fuel cell system, the heat exchange device includes a fan used for cooling the first compressed gas flowing through the connection flow path, and the control unit controls the rotation speed of the fan, thereby controlling the turbo It is good to control the inhalation temperature.

According to such a configuration, the turbo intake temperature can be controlled by a relatively simple control such as the control of the rotational speed of the fan.
In the fuel cell system, the heat exchange device includes a refrigerant flow path through which a refrigerant flows, a pump device that circulates the refrigerant in the refrigerant flow path, and heat that exchanges heat between the refrigerant and the first compressed gas. An exchange unit, a radiator that exchanges heat with the refrigerant, and a fan that blows air to the radiator, and the control unit has a rotation speed of the fan and a unit time of the refrigerant that flows through the refrigerant flow path The turbo intake temperature may be controlled by controlling at least one of the hit flow rates.

  According to such a configuration, by controlling at least one of the rotational speed of the fan and the flow rate per unit time of the refrigerant flowing through the refrigerant flow path, the temperature of the turbo intake temperature can be set to the target temperature, through which the turbine The rotational speed can be controlled.

  According to the present invention, the rotational speed of the turbine can be controlled while suppressing fluctuations in the pressure of the oxidant gas supplied to the fuel cell.

The block diagram which shows the outline | summary of a fuel cell system. The conceptual diagram for demonstrating derived data.

Hereinafter, an embodiment of the present fuel cell system will be described. Note that the fuel cell system of this embodiment is mounted on a vehicle.
As shown in FIG. 1, the fuel cell system 10 includes a fuel cell stack 11 as a fuel cell that generates electric power by an electrochemical reaction between a fuel gas that is an anode gas and an oxidant gas that is a cathode gas. The fuel cell system 10 includes a fuel gas supply unit 20 that supplies fuel gas to the fuel cell stack 11, an oxidant gas supply unit 30 that supplies oxidant gas to the fuel cell stack 11, And an oxidant gas discharge unit 40 for discharging the oxidant gas.

  The fuel cell stack 11 has a plurality of cells, for example. Each cell is configured by laminating a cathode electrode, an anode electrode, and a separator (electrolyte membrane) disposed between both electrodes, and power is generated by supplying fuel gas and oxidant gas. To do. The fuel gas is, for example, hydrogen. The oxidant gas is arbitrary as long as it contains oxygen, but is, for example, air.

  In the fuel cell stack 11, an anode flow path 12 through which the fuel gas supplied from the fuel gas supply unit 20 flows and a cathode flow path 13 through which the oxidant gas flows are formed. The cathode flow path 13 has a supply port 13a through which the oxidant gas is supplied through the oxidant gas supply unit 30, and a discharge port 13b through which the oxidant gas is discharged.

  The fuel cell stack 11 includes a stack temperature detection unit 14 for detecting a stack temperature Ts that is the temperature of the fuel cell stack 11. The stack temperature detection unit 14 detects a physical quantity having a correlation with the stack temperature Ts. The stack temperature detection unit 14 detects the temperature of the cells of the fuel cell stack 11 as the physical quantity, for example. However, the present invention is not limited to this. For example, when the fuel cell system 10 includes a cooling mechanism that cools the fuel cell stack 11 using a refrigerant, the stack temperature detection unit 14 uses the fuel cell stack of the refrigerant as the physical quantity. 11 may be detected, and the stack temperature Ts may be estimated from the detection result.

  The fuel gas supply unit 20 includes a tank in which fuel gas is stored and a pump device, and supplies the fuel gas in the tank to the anode flow path 12 using the pump device. Further, the fuel gas supply unit 20 circulates the fuel gas discharged from the fuel cell stack 11 through the anode channel 12 to the anode channel 12 again.

  The oxidant gas supply unit 30 includes an electric compressor 31, a turbo compressor 32, a suction passage 33 for introducing the oxidant gas into the electric compressor 31, a connection passage 34 connecting the electric compressor 31 and the turbo compressor 32, and a turbo. And a supply flow path 35 that connects the compressor 32 and the fuel cell stack 11.

  The electric compressor 31 compresses the oxidant gas sucked from the suction flow path 33 and discharges the compressed first compressed gas to the connection flow path 34. The electric compressor 31 includes a compression unit 31a and an electric motor 31b that drives the compression unit 31a.

  The compression unit 31a has a rotating body, and performs a compression operation when the rotating body rotates. The specific type of the compression unit 31a is arbitrary, and may be, for example, a turbo type having an impeller, a scroll type, a roots type, or the like. The rotating body of the compression unit 31a rotates at a rotation speed corresponding to the torque N of the electric motor 31b.

  Here, the supply flow rate FI, which is the flow rate of the oxidant gas supplied to the fuel cell stack 11, is determined by the driving mode of the electric compressor 31, specifically, the torque N of the electric motor 31b. Specifically, the supply flow rate FI is determined by the momentum per time that the rotating body of the compression unit 31a applies to the oxidant gas, and the momentum is determined by the torque N of the electric motor 31b. If attention is paid to this point, it can be said that the supply flow rate FI is a parameter controlled by the electric motor 31b.

  The turbo compressor 32 is provided downstream of the electric compressor 31 and upstream of the fuel cell stack 11 in the flow direction of the oxidant gas. The suction side of the turbo compressor 32 is connected to the connection flow path 34, and the discharge side of the turbo compressor 32 is connected to the supply flow path 35. The turbo compressor 32 includes an impeller 32a as a rotating body, and the impeller 32a rotates to compress the first compressed gas flowing through the connection flow path 34, and the compressed second compressed gas is supplied to the supply flow path 35. To be discharged.

  Each of the connection flow path 34 and the supply flow path 35 is configured by piping or the like. The connection channel 34 is a channel through which the first compressed gas flows, and the supply channel 35 is a channel through which the second compressed gas flows. The supply channel 35 is connected to the supply port 13 a in the cathode channel 13 of the fuel cell stack 11.

  According to this configuration, the oxidant gas sucked from the suction flow path 33 is compressed in two stages by the compressors 31 and 32 and supplied to the cathode flow path 13 from the supply port 13a. As a result, the supply pressure PI that is the pressure of the oxidant gas supplied to the cathode channel 13 is increased. The supply pressure PI is the pressure of the second compressed gas supplied to the fuel cell stack 11.

The oxidant gas discharge unit 40 includes a discharge channel 41 through which exhaust gas discharged from the fuel cell stack 11 flows, a change unit 42 provided in the discharge channel 41, and a turbine 43.
The discharge channel 41 is constituted by, for example, piping. One end of the discharge channel 41 is connected to the discharge port 13 b of the cathode channel 13 in the fuel cell stack 11, and the other end of the discharge channel 41 is connected to the turbine 43. That is, the fuel cell stack 11 and the turbine 43 are connected via the discharge channel 41. Exhaust gas discharged from the fuel cell stack 11 through the discharge port 13 b of the cathode flow path 13 is introduced into the turbine 43 through the discharge flow path 41.

The changing unit 42 changes the cross-sectional area of the discharge flow channel 41. The changing unit 42 includes a variable nozzle 42a and an actuator 42b.
The variable nozzle 42 a is configured to be able to change the flow path cross-sectional area of the discharge flow path 41. In detail, the variable nozzle 42a is configured by, for example, one or a plurality of valves that are provided in the discharge flow path 41 and that can adjust the opening degree θ. The area can be changed. That is, the opening degree θ is a parameter that defines the flow path cross-sectional area, and the control of the opening degree θ can be said to be control of the flow path cross-sectional area.

  The specific configuration of the variable nozzle 42a is arbitrary. For example, the variable nozzle 42a is arranged in the circumferential direction at a position on the outer periphery of the turbine 43, and the flow passage cross-sectional area is adjusted by rotating. Vane etc. may be sufficient. In this case, the opening degree θ corresponds to the rotation angle of the vane. The variable nozzle 42a can be said to be a variable throttle that throttles the discharge channel 41 and that can change the degree of throttling.

The supply pressure PI changes according to the opening degree θ of the variable nozzle 42a. Therefore, the supply pressure PI is a parameter controlled by the opening degree θ of the variable nozzle 42a.
The actuator 42b drives the variable nozzle 42a so that the opening degree θ of the variable nozzle 42a is changed. The control of the opening degree θ is realized by the control of the actuator 42b.

  The turbine 43 converts the fluid energy of the exhaust gas that has passed through the changing unit 42 into mechanical energy. Specifically, the turbine 43 is configured by an impeller having blades formed therein, and is configured to rotate when exhaust gas that has passed through the variable nozzle 42a is blown. In this case, the exhaust gas expands by passing through the turbine 43. As a result, the gas discharged from the turbine 43 has a lower pressure and a lower temperature than the exhaust gas introduced into the turbine 43, in other words, the exhaust gas that has passed through the variable nozzle 42a. For convenience of illustration, the variable nozzle 42a and the turbine 43 are shown as separate bodies, but both are actually integrated.

  As shown in FIG. 1, the fuel cell system 10 includes a pressure detector 51 that detects the pressure of exhaust gas discharged from the fuel cell stack 11. The pressure detection unit 51 detects the pressure of the exhaust gas from the discharge port 13b of the cathode channel 13 toward the variable nozzle 42a.

  There is a correlation between the pressure of the exhaust gas detected by the pressure detector 51 and the supply pressure PI. Specifically, the supply pressure PI is higher than the pressure of the exhaust gas by an amount corresponding to the loss caused by the second compressed gas flowing through the cathode flow path 13. If the loss can be ignored, the pressure of the exhaust gas and the supply pressure PI can be regarded as the same. For this reason, the fuel cell system 10 can grasp the supply pressure PI from the detection result of the pressure detector 51. If attention is paid to this point, it can be said that the pressure detector 51 is used to detect the supply pressure PI.

  The fuel cell system 10 includes a connecting portion 52 that connects the impeller 32 a of the turbo compressor 32 and the turbine 43. The impeller 32a of the turbo compressor 32 and the turbine 43 are rotated together by a connecting portion 52. Accordingly, the turbo compressor 32 is automatically driven by the rotation of the turbine 43 by the exhaust gas. That is, the turbine 43 drives the turbo compressor 32 by the rotational force obtained from the exhaust gas introduced in a state of being throttled by the variable nozzle 42a. Therefore, two-stage compression is realized without providing a dedicated electric motor for driving the turbo compressor 32. In this case, the rotational speed v of the turbo compressor 32 and the turbine 43 is the same. For convenience of explanation, in the following explanation, the rotational speed v between the turbo compressor 32 and the turbine 43 is simply referred to as the turbine rotational speed v.

  Here, the efficiency η of the turbine 43 (hereinafter simply referred to as “turbine efficiency η”) changes in accordance with the turbine rotational speed v. The turbine efficiency η is, for example, the ratio of the output (power) of the turbine 43 to the amount of heat consumed by the turbine 43. Specifically, the amount of heat of gas (that is, exhaust gas) introduced into the turbine 43 and the amount of heat discharged from the turbine 43. This is the ratio of the output of the turbine 43 to the difference from the heat quantity of the gas. If the turbine efficiency η is high, the second pressure ratio Rb, which is the pressure ratio of the turbo compressor 32, tends to be high, whereas if the turbine efficiency η is low, the second pressure ratio Rb tends to be low. The second pressure ratio Rb is the ratio of the supply pressure PI to the pressure P1 of the first compressed gas (= PI / P1).

  On the other hand, the fuel cell system 10 of the present embodiment has a configuration that increases the turbine efficiency η. The configuration will be described together with the configuration related to the control of the fuel cell system 10.

  As shown in FIG. 1, the fuel cell system 10 includes a heat exchange device 60 that exchanges heat with the first compressed gas flowing through the connection flow path 34, and a turbo that is the temperature of the first compressed gas sucked into the turbo compressor 32. And a turbo suction temperature detector 67 for detecting the suction temperature Tv.

  The heat exchange device 60 is used for cooling the refrigerant flow path 61 through which the refrigerant flows, the pump device 62 that circulates the refrigerant in the refrigerant flow path 61, the heat exchange section 63 and the radiator 64 that perform heat exchange, and the first compressed gas. The fan 65 and the fan drive unit 66 are provided.

  The refrigerant flow path 61 has a closed loop shape so that the refrigerant circulates. In the present embodiment, the refrigerant flow path 61 is provided independently of other refrigerant flow paths mounted on the vehicle. In the present embodiment, the refrigerant is a liquid. However, the present invention is not limited to this, and the refrigerant may be a gas.

  The pump device 62 is provided in the refrigerant channel 61 and circulates the refrigerant at a predetermined speed by sucking and discharging the refrigerant. In this case, the flow rate of the refrigerant flowing through the refrigerant flow path 61 per unit time varies depending on the driving mode of the pump device 62. For example, when the pump device 62 has a rotating body and is configured to circulate the refrigerant by rotating the rotating body, the drive mode of the pump device 62 is the rotational speed of the rotating body. is there. The specific configuration of the pump device 62 is arbitrary such as a trochoid type.

  The heat exchanging unit 63 transmits the heat of the first compressed gas to the refrigerant. The heat exchanging unit 63 is made of a material having high thermal conductivity, and is made of a metal such as aluminum, for example. A part of the refrigerant flow path 61 and a part of the connection flow path 34 are formed in the heat exchanging unit 63, and both are arranged in parallel at positions close to each other. Heat exchange is performed between the refrigerant in the refrigerant flow path 61 and the first compressed gas via the heat exchange unit 63. In other words, the heat exchange unit 63 thermally couples the refrigerant in the refrigerant flow path 61 and the first compressed gas in the connection flow path 34.

  A part of the refrigerant flow path 61 is formed inside the radiator 64. The refrigerant exchanges heat with the radiator 64 by flowing in the radiator 64. That is, the radiator 64 absorbs the heat of the refrigerant flowing through the radiator 64. The specific configuration of the radiator 64 is arbitrary.

  In the present embodiment, the fan 65 cools the radiator 64 by sending air to the radiator 64. That is, in the present embodiment, the blower object of the fan 65, that is, the cooling object is the radiator 64.

  The fan driving unit 66 drives the fan 65. The fan drive unit 66 includes, for example, a motor that rotates the fan 65 and an inverter circuit that drives the motor. The fan drive unit 66 is configured to be able to rotate and stop the fan 65 and to change the rotation speed of the fan 65.

  According to this configuration, the heat of the first compressed gas flowing through the connection flow path 34 is transmitted to the refrigerant in the refrigerant flow path 61 through the heat exchange unit 63. The heat of the refrigerant is transmitted to the radiator 64, and the heat of the radiator 64 is released to the air blown by the fan 65. That is, the first compressed gas is cooled by the fan 65 through the heat exchange unit 63, the refrigerant, and the radiator 64.

  Here, the amount of heat absorbed by the radiator 64 with respect to the refrigerant changes according to the flow rate of the air supplied to the radiator 64. The flow rate of the air supplied to the radiator 64 changes according to the rotational speed of the fan 65. For this reason, by adjusting the rotational speed of the fan 65, the temperature of the refrigerant can be adjusted, and the turbo suction temperature Tv can be adjusted through it. That is, the heat exchange device 60 of the present embodiment is configured to be able to adjust the turbo suction temperature Tv by controlling the rotational speed of the fan 65.

  The inventors of the present application indicate that there is a correlation between the turbo suction temperature Tv, which is the temperature of the first compressed gas sucked into the turbo compressor 32, and the turbine rotational speed v. Specifically, the turbo suction temperature Tv is It has been found that the turbine rotational speed v changes as it changes. Specifically, for example, when the present fuel cell system 10 is operating so that the fuel cell stack 11 generates a predetermined amount of power generation under the condition that the turbo suction temperature Tv is the first temperature, When the turbo intake temperature Tv changes from the first temperature to the second temperature due to the change in the rotation speed, the turbine rotation speed v changes accordingly. That is, the turbine rotational speed v is a parameter controlled by the turbo intake temperature Tv, and in detail is a parameter controlled by the rotational speed of the fan 65.

  The turbo suction temperature detection unit 67 is provided in the downstream portion of the heat exchange unit 63 in the connection flow path 34. The turbo suction temperature detection unit 67 detects the turbo suction temperature Tv, specifically, the temperature of the first compressed gas that is sucked into the turbo compressor 32 and has undergone heat exchange with the heat exchange device 60. . The turbo intake temperature detection unit 67 is, for example, a temperature sensor.

  As shown in FIG. 1, the fuel cell system 10 includes a control device 70 that functions as a control unit that controls the electric motor 31 b, the changing unit 42 (actuator 42 b), the pump device 62, and the fan 65.

  The control device 70 includes a grasping unit 71 that grasps the stack temperature Ts, the turbo suction temperature Tv, and the supply pressure PI. Specifically, each of the stack temperature detection unit 14, the turbo intake temperature detection unit 67, and the pressure detection unit 51 outputs the detection result to the control device 70. The grasping unit 71 of the control device 70 grasps the stack temperature Ts based on the detection result of the stack temperature detecting unit 14, and grasps the turbo intake temperature Tv based on the detection result of the turbo intake temperature detecting unit 67. The grasping unit 71 grasps the supply pressure PI based on the detection result of the pressure detecting unit 51.

  The stack temperature Ts varies depending on the operating state of the fuel cell system 10. For this reason, the grasping unit 71 grasps a plurality of types of stack temperatures Ts having different values. For convenience of explanation, a plurality of types of stack temperatures Ts grasped by the grasping unit 71 may be indicated as stack temperatures Ts1, Ts2,..., Tsn (where n is an arbitrary natural number).

  Further, the grasping unit 71 grasps the required power generation amount Pw required for the fuel cell system 10. Specifically, the control device 70 is electrically connected to the vehicle ECU 100 mounted on the vehicle, and exchanges signals. The vehicle ECU 100 calculates a required power generation amount Pw based on an operation mode of an accelerator pedal provided in the vehicle and notifies the grasping unit 71 of the control device 70 of the required power generation amount Pw. The grasping unit 71 grasps the required power generation amount Pw based on the notification from the vehicle ECU 100.

  The vehicle ECU 100 notifies the grasping unit 71 of the control device 70 of the required power generation amount Pw having a different value depending on the situation. For this reason, the grasping | ascertainment part 71 grasps | ascertains the multiple types of required power generation amounts Pw having different values. For convenience of explanation, the plurality of types of required power generation amounts Pw grasped by the grasping unit 71 may be indicated as required power generation amounts Pw1, Pw2,..., Pwm (where m is an arbitrary natural number). The grasping unit 71 can also be said to be an acquisition unit that acquires the stack temperature Ts, the turbo intake temperature Tv, the supply pressure PI, and the required power generation amount Pw.

  The control device 70 controls the opening degree θ of the variable nozzle 42a and the torque N of the electric motor 31b based on the required power generation amount Pw and the stack temperature Ts that are grasped by the grasping unit 71, and the turbine efficiency η. The suction temperature Tv, in this embodiment, the rotational speed of the fan 65 is controlled. These specific control modes will be described in detail below.

  The control device 70 derives the target temperature Tvx, which is the target value of the target opening degree θx of the variable nozzle 42a, the target torque Nx of the electric motor 31b, and the turbo intake temperature Tv, based on the grasping result of the grasping unit 71. 72. The deriving unit 72 includes derived data 72a used for deriving the target opening θx, the target torque Nx, and the target temperature Tvx.

  As shown in FIG. 2, the derived data 72a is map data in which the target opening degree θx, the target torque Nx, and the target temperature Tvx are set in association with the required power generation amount Pw and the stack temperature Ts, for example. For example, the target opening degree θx (1, 1), the target torque Nx (1, 1), and the target temperature Tvx (1, 1) are set in correspondence with the first required power generation amount Pw1 and the first stack temperature Ts1. Yes.

  .., Pwm and a plurality of types of stack temperatures Ts1, Ts2,..., Tsn are grasped in the derived data 72a. A plurality of types of stack temperatures Ts1, Ts2,..., Tsn are set in association with each of Pw2,. In the derived data 72a, the target opening degree θx, the target torque Nx, and the target temperature Tvx corresponding to combinations of the required power generation amounts Pw1, Pw2,..., Pwm and the stack temperatures Ts1, Ts2,. For example, the target opening degree θx (m, n), the target torque Nx (m, n), and the target temperature Tvx (m, n) are set in correspondence with the m-th required power generation amount Pwm and the n-th stack temperature Tsn. Yes.

  When the required power generation amount Pw is grasped by the grasping unit 71, that is, when the vehicle ECU 100 has notified the required power generation amount Pw, the derivation unit 72 refers to the derivation data 72a to obtain the required power generation amount Pw. The target opening degree θx, the target torque Nx, and the target temperature Tvx corresponding to both the current stack temperature Ts grasped by the grasping unit 71 are derived.

  The control device 70 controls the actuator 42b of the changing unit 42 so that the opening θ of the variable nozzle 42a becomes the target opening θx, and controls the electric motor 31b so that the electric motor 31b is driven with the target torque Nx. To do.

  Further, the control device 70 controls the heat exchanging device 60 based on the detection result of the turbo intake temperature detection unit 67 so that the turbo intake temperature Tv matches the target temperature Tvx. Specifically, the control device 70 feedback-controls the rotational speed of the fan 65 based on the detection result of the turbo intake temperature detection unit 67 so that the turbo intake temperature Tv becomes the target temperature Tvx. Actually, the control device 70 controls the drive mode of the fan drive unit 66 (for example, inverter control).

  In the present embodiment, the control device 70 controls the pump device 62 so that the refrigerant flows through the refrigerant flow path 61 at a constant speed. For this reason, the flow rate per unit time of the refrigerant flowing through the refrigerant flow path 61 is constant.

Next, the relationship between the required power generation amount Pw and the stack temperature Ts, the target opening degree θx, the target torque Nx, and the target temperature Tvx will be described.
The amount of power generated by the fuel cell stack 11 depends on the stack temperature Ts and the supply flow rate FI and supply pressure PI, which are the flow rate and pressure of the second compressed gas supplied to the fuel cell stack 11. In such a configuration, if the stack temperature Ts is grasped, the supply flow rate FI and the supply pressure PI necessary for setting the power generation amount of the fuel cell stack 11 to the required power generation amount Pw are determined. For convenience of explanation, it is assumed that the supply flow rate FI and the supply pressure PI necessary for generating the required power generation amount Pw are the target flow rate FIx and the target pressure PIx.

  Here, as already described, the supply flow rate FI depends on the torque N of the electric motor 31b, and the supply pressure PI depends on the opening θ of the variable nozzle 42a. Further, the turbine efficiency η changes according to the turbine rotational speed v, and the turbine rotational speed v changes according to the turbo intake temperature Tv.

  In this case, the target opening θx, the target torque Nx, and the target temperature Tvx are the supply flow rate FI under the conditions that the opening θ, the torque N, and the turbo intake temperature Tv are the target opening θx, the target torque Nx, and the target temperature Tvx. The supply pressure PI is set to correspond to the stack temperature Ts so that the target flow rate FIx and the target pressure PIx become the maximum and the turbine efficiency η becomes maximum.

Specifically, the target opening degree θx is set so that the supply pressure PI becomes the target pressure PIx.
The target temperature Tvx is set based on the turbine efficiency η. Specifically, when the turbine rotational speed v at which the turbine efficiency η is maximum under the condition that the supply flow rate FI and the supply pressure PI are the target flow rate FIx and the target pressure PIx, is the target rotational speed vx, the target temperature Tvx is The turbine rotation speed v is set to the turbo suction temperature Tv at which the target rotation speed vx is obtained.

  Here, the second pressure ratio Rb, which is the pressure ratio of the turbo compressor 32, changes according to the turbine rotational speed v (in other words, the turbo intake temperature Tv). For this reason, when the turbo intake temperature Tv is set to the target temperature Tvx, the second pressure ratio Rb is uniquely determined.

  Further, the first pressure ratio Ra which is the pressure ratio of the electric compressor 31 and the power consumption of the electric compressor 31 differ according to the torque N. The first pressure ratio Ra is a ratio (= P1 / P0) of the pressure P1 of the first compressed gas to the pressure P0 of the oxidant gas sucked into the electric compressor 31 from the suction flow path 33. The pressure P0 of the oxidant gas sucked into the electric compressor 31 is, for example, atmospheric pressure.

  In such a configuration, the ratio of the target pressure PIx to the pressure P0 of the oxidant gas sucked into the electric compressor 31 is set as the target pressure ratio Rx (= PIx / P0). In this case, the pressure P0 of the oxidant gas sucked into the electric compressor 31 under the condition where the turbo intake temperature Tv is set to the target temperature Tvx, that is, under the condition where the turbine rotational speed v is the target rotational speed vx. The first pressure ratio Ra for the ratio (= PI / P0) of the supply pressure PI to the target pressure ratio Rx is a specific pressure ratio Rax. In this case, the target torque Nx is set to a value such that the supply flow rate FI becomes the target flow rate FIx and the first pressure ratio Ra becomes the specific pressure ratio Rax within the operable range.

  Incidentally, if attention is paid to the fact that the target temperature Tvx is set based on the turbine efficiency η, the derivation unit 72 determines the target opening degree θx, the target torque based on the required power generation amount Pw, the stack temperature Ts, and the turbine efficiency η. It can be said that Nx and the target temperature Tvx are derived.

  The grasping unit 71 periodically grasps the supply pressure PI based on the detection result of the pressure detecting unit 51, and the control device 70 finely adjusts the opening degree θ of the variable nozzle 42a based on the grasping result. May be performed. In this case, the derivation unit 72 derives the target pressure PIx in addition to the target opening degree θx, the target torque Nx, and the target temperature Tvx based on the required power generation amount Pw and the stack temperature Ts. The opening degree θ of the variable nozzle 42a may be feedback controlled so that PI becomes the target pressure PIx.

Next, the operation of this embodiment will be described.
By controlling the turbo suction temperature Tv, the turbine rotational speed v becomes the target rotational speed vx set based on the turbine efficiency η, and thus the turbine efficiency η is high. Thereby, since the turbo compressor 32 is driven with high efficiency, the second pressure ratio Rb tends to increase. Accordingly, the specific pressure ratio Rax, which is the first pressure ratio Ra necessary for obtaining the target pressure ratio Rx, is likely to be low, so that the torque N of the electric motor 31b can be easily reduced. Therefore, power consumption in the electric compressor 31 tends to be small.

According to the embodiment described above in detail, the following effects are obtained.
(1) The oxidant gas is compressed by the electric compressor 31 and the turbo compressor 32. Thereby, compared with the case where only the electric compressor 31 is used, the first pressure ratio Ra which is the pressure ratio of the electric compressor 31 required for the required power generation amount Pw is reduced. Therefore, the power consumption of the electric compressor 31 can be reduced. Moreover, since the turbo compressor 32 is driven using the rotational force of the turbine 43, a dedicated electric motor or the like is not required separately as a drive source.

  Further, the turbo intake temperature Tv is a target temperature Tvx derived by the heat exchanging device 60 based on the grasping result of the grasping unit 71 and the turbine efficiency η. As a result, the turbine rotation speed v can be set to the target value, specifically, the turbine efficiency η is high while suppressing the fluctuation of the supply pressure PI (in other words, the change in the opening degree θ of the variable nozzle 42a).

  More specifically, for controlling the turbine rotation speed v, for example, the opening degree θ of the variable nozzle 42a can be considered. However, the opening θ of the variable nozzle 42a is a parameter that contributes to the supply pressure PI. For this reason, if the opening degree θ of the variable nozzle 42a is set so as to correspond to the turbine rotational speed v at which the turbine efficiency η is high, the supply pressure PI deviates from the value (target pressure PIx) corresponding to the required power generation amount Pw. In some cases, the fuel cell stack 11 cannot obtain a power generation amount corresponding to the required power generation amount Pw.

  On the other hand, the fuel cell system 10 of the present embodiment newly adopts the turbo intake temperature Tv as a parameter for controlling the turbine rotational speed v, and heat exchange is a configuration for controlling the turbo intake temperature Tv. A device 60 is provided. Thereby, the turbine rotational speed v can be controlled while setting the opening degree θ of the variable nozzle 42a to a value corresponding to the supply pressure PI.

  (2) The target temperature Tvx is a turbo intake temperature Tv at which the turbine rotational speed v becomes the target rotational speed vx. The target rotational speed vx is the turbine efficiency η under the condition that the supply flow rate FI and the supply pressure PI are the target flow rate FIx and the target pressure PIx corresponding to the required power generation amount Pw and the stack temperature Ts grasped by the grasping unit 71. Is the maximum turbine rotational speed v. According to such a configuration, since the turbine efficiency η can be maximized, the power consumption of the electric compressor 31 can be reduced.

  (3) The control device 70 controls the heat exchanging device 60 so that the turbo suction temperature Tv becomes the target temperature Tvx based on the detection result of the turbo suction temperature detection unit 67. According to such a configuration, the turbo intake temperature detection unit 67 can directly grasp the turbo intake temperature Tv. As a result, the turbo intake temperature Tv can be controlled with high accuracy.

  In particular, the fuel cell system 10 controls the turbine rotational speed v by controlling the turbo intake temperature Tv. Therefore, for example, in the control in which the target temperature Tvx is not clearly defined such that the temperature of the first compressed gas flowing through the connection flow path 34 is lowered within a possible range, the turbine rotation speed v can be appropriately controlled. Therefore, there is a problem that the turbine efficiency η cannot be improved.

  On the other hand, according to the present embodiment, as described above, the target temperature Tvx is derived by the deriving unit 72 so that the turbo intake temperature Tv detected by the turbo intake temperature detecting unit 67 coincides with the target temperature Tvx. Since it is controlled, the turbine rotational speed v can be appropriately controlled, and the above-mentioned disadvantages can be suppressed.

In addition, you may change the said embodiment as follows.
In the embodiment, the control device 70 is configured to control the turbo suction temperature Tv by controlling the rotational speed of the fan 65, but is not limited thereto. For example, the control device 70 may be configured to control the turbo suction temperature Tv by controlling the flow rate of the refrigerant flowing through the refrigerant flow path 61 per unit time instead of the rotational speed of the fan 65. Specifically, the control device 70 may control the flow rate per unit time of the refrigerant flowing through the refrigerant flow path 61 by controlling the driving mode of the pump device 62. In this case, the fan 65 may be omitted.

  The control device 70 may be configured to control both the rotational speed of the fan 65 and the flow rate per unit time of the refrigerant flowing through the refrigerant flow path 61. In short, the control device 70 may control at least one of the rotational speed of the fan 65 and the flow rate per unit time of the refrigerant flowing through the refrigerant flow path 61.

  O Although the refrigerant flow path 61 of embodiment was provided independently, it is not restricted to this, It is provided separately from the fuel cell system 10, Comprising: Other refrigerant flow paths mounted in the vehicle It may also be configured to be used together. For example, the refrigerant channel 61 of the present fuel cell system 10 may be formed by extending a part of the other refrigerant channel. In this case, when a pump device is provided in the other refrigerant flow path, the pump device 62 on the refrigerant flow path 61 may be omitted. That is, it is not essential that the fuel cell system 10 includes the pump device 62. As described above, in the configuration in which the same refrigerant is used in both the refrigerant flow path 61 and the other refrigerant flow paths, the control device 70 provides the refrigerant flow so that the turbo intake temperature Tv can be controlled. It is good to be comprised so that the refrigerant | coolant which flows through the path | route 61 and said other refrigerant | coolant flow path can be controlled. In this case, the heat exchanging device 60 can be controlled so that the turbo suction temperature Tv matches the target temperature Tvx regardless of the temperature of the refrigerant flowing from the other refrigerant flow path into the radiator 64 through the refrigerant flow path 61. desirable.

  The specific configuration of the heat exchange device 60 is not limited to that of the embodiment, and may be arbitrary as long as heat exchange with the first compressed gas is possible and the heat exchange mode is controllable. For example, the air blow target of the fan 65 is not limited to the radiator 64, but may be the heat exchange unit 63.

In the embodiment, the target rotational speed vx is the turbine rotational speed v at which the turbine efficiency η is maximized. However, the target rotational speed vx is not limited to this, and may be set to a value other than this.
For example, the target rotational speed vx may be set to a turbine rotational speed v at which the turbine efficiency η is equal to or higher than a predetermined threshold efficiency. Even in this case, it is possible to realize a state in which the turbine efficiency η is equal to or higher than the threshold efficiency while realizing the power generation of the required power generation amount Pw in the fuel cell stack 11. In other words, the control device 70 may control the turbo intake temperature Tv so that the turbine efficiency η does not become less than the threshold efficiency.

  For example, when the turbine rotational speed v at which the second pressure ratio Rb is maximized is different from the turbine rotational speed v at which the turbine efficiency η is maximized, the target rotational speed vx is the maximum at the second pressure ratio Rb. It may be set to the turbine rotation speed v. Further, the target rotational speed vx may be set to a turbine rotational speed v that maximizes the overall power generation efficiency of the fuel cell system 10 in consideration of the turbine efficiency η and the power consumption of the electric compressor 31.

  The turbo suction temperature detection unit 67 may be omitted. In this case, in the derived data 72a, the target rotational speed of the fan 65 is set instead of the turbo suction temperature Tv, and the control device 70 determines that the rotational speed of the fan 65 becomes the target rotational speed. The drive unit 66) may be controlled. In such a configuration, the target rotation speed of the fan 65 is set to a value at which the turbo suction temperature Tv becomes the target temperature Tvx.

  A specific configuration of the deriving unit 72, that is, a specific control mode for deriving the target opening θx, the target torque Nx, and the target temperature Tvx is not limited to that of the embodiment, and is arbitrary. For example, the derived data 72a may be function data instead of map data. Further, the deriving unit 72 derives the target flow rate FIx and the target pressure PIx based on the required power generation amount Pw and the stack temperature Ts, and based on the derived target flow rate FIx and target pressure PIx, the target opening degree θx, The target torque Nx and the target temperature Tvx may be derived. In this case, the deriving unit 72 includes data in which the target flow rate FIx and the target pressure PIx are associated with the required power generation amount Pw and the stack temperature Ts, and the target opening degree θx and the target pressure with respect to the target flow rate FIx and the target pressure PIx. It is preferable to have data associated with the torque Nx and the target temperature Tvx, and perform the derivation process using these data.

  ○ At least one of the grasping unit 71 and the deriving unit 72 may be provided separately from the control device 70. In short, it is not essential for the control device 70 to include the grasping unit 71 and the deriving unit 72, and the fuel cell system 10 as a whole has a "recognizing unit", a "derivation unit", and a "control unit". It only has to be.

  The mounting target of the fuel cell system 10 is not limited to the vehicle, and may be another electric machine in which the amount of power generation required in the fuel cell system 10 changes depending on the operation state.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell system, 11 ... Fuel cell stack (fuel cell), 14 ... Stack temperature detection part, 31 ... Electric compressor, 31a ... Compression part, 31b ... Electric motor, 32 ... Turbo compressor, 32a ... Impeller, 34 ... Connection Flow path, 41 ... Discharge flow path, 42 ... Change part, 42a ... Variable nozzle, 42b ... Actuator, 43 ... Turbine, 52 ... Connection part, 60 ... Heat exchange device, 61 ... Refrigerant flow path, 62 ... Pump device, 63 ... Heat exchange section, 64 ... Radiator, 65 ... Fan, 67 ... Turbo intake temperature detection section, 70 ... Control device, 71 ... Grasping section, 72 ... Derivation section, 72a ... Derived data, Pw ... Required power generation amount, Ts ... Stack Temperature (temperature of the fuel cell), Tv ... turbo intake temperature, Tvx ... target temperature, PI ... supply pressure, PIx ... target pressure, FI ... supply flow, FIx ... target flow, ... opening, [theta] x ... target opening, N ... torque, Nx ... target torque, v ... turbine rotational speed, vx ... target rotational speed, eta ... turbine efficiency, Rax ... specific pressure ratio, Rx ... target pressure ratio.

Claims (6)

An electric compressor that compresses the oxidant gas;
A turbo compressor that compresses the first compressed gas that is the oxidant gas compressed by the electric compressor and has an impeller;
A fuel cell supplied with a second compressed gas which is the oxidant gas compressed by the turbo compressor;
Connecting the electric compressor and the turbo compressor, the connection flow path through which the first compressed gas flows;
A turbine that is connected to the fuel cell via an exhaust passage through which exhaust gas discharged from the fuel cell flows, and is rotated by the exhaust gas;
A connecting portion that connects the impeller and the turbine so that the impeller of the turbo compressor and the turbine rotate together;
A change unit that is provided in the discharge channel and changes a cross-sectional area of the discharge channel;
A heat exchange device for exchanging heat with the first compressed gas flowing through the connection flow path;
A grasping unit for grasping a required power generation amount that is a power generation amount required in the fuel cell and a temperature of the fuel cell;
Based on the required power generation amount and the temperature of the fuel cell that are grasped by the grasping unit, and the efficiency of the turbine, the temperature of the first compressed gas after heat exchange with the heat exchange device is performed. A deriving unit for deriving a target temperature that is a target value for a certain turbo intake temperature;
A control unit that controls the heat exchange device such that the turbo suction temperature becomes the target temperature;
A fuel cell system comprising: The supply flow rate and supply pressure, which are the flow rate and pressure of the second compressed gas supplied to the fuel cell, correspond to the required power generation amount and the temperature of the fuel cell that are grasped by the grasping unit. When the rotational speed of the turbine that maximizes the efficiency of the turbine under the pressure condition is the target rotational speed,
2. The fuel cell system according to claim 1, wherein the target temperature is the turbo intake temperature at which a rotation speed of the turbine becomes the target rotation speed. The changing unit includes a variable nozzle and an actuator that drives the variable nozzle so that the opening degree of the variable nozzle is changed.
The electric compressor has a compression unit that compresses the oxidant gas, and an electric motor that drives the compression unit,
In addition to deriving the target temperature based on the required power generation amount, the temperature of the fuel cell, and the efficiency of the turbine obtained by the grasping unit, the deriving unit includes a target opening corresponding to the target pressure. And a target torque corresponding to the target flow rate is derived,
In addition to controlling the heat exchange device, the control unit controls the actuator so that the opening degree of the variable nozzle becomes the target opening degree, and the torque of the electric motor becomes the target torque. Controlling the electric motor,
The ratio of the target pressure to the pressure of the oxidant gas sucked into the electric compressor is a target pressure ratio, and the oxidant sucked into the electric compressor under the condition that the rotational speed of the turbine is the target rotational speed. When the pressure ratio of the electric compressor for the ratio of the supply pressure to the gas pressure to be the target pressure ratio is a specific pressure ratio,
The fuel cell system according to claim 2, wherein the target torque is set to a value at which the supply flow rate becomes the target flow rate and a pressure ratio of the electric compressor becomes the specific pressure ratio. A turbo suction temperature detection unit for detecting the turbo suction temperature;
The said control part controls the said heat exchange apparatus so that the said turbo intake temperature detected by the said turbo intake temperature detection part and the said target temperature may correspond. Fuel cell system. The heat exchange device includes a fan used for cooling the first compressed gas flowing through the connection flow path,
The fuel cell system according to any one of claims 1 to 4, wherein the control unit controls the turbo suction temperature by controlling a rotation speed of the fan. The heat exchange device
A refrigerant flow path through which the refrigerant flows;
A pump device for circulating the refrigerant in the refrigerant flow path;
A heat exchanging unit in which heat exchange is performed between the refrigerant and the first compressed gas;
A radiator that exchanges heat with the refrigerant;
A fan for blowing air to the radiator;
With
The said control part controls the said turbo suction temperature by controlling at least one of the rotational speed of the said fan, and the flow volume per unit time of the said refrigerant | coolant which flows through the said refrigerant | coolant flow path. The fuel cell system as described in any one of them.

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