Fuel cell unit

Abstract

To prevent the smoothing capacitor from overheating due to heat generated on the boost converter side.SOLUTION: A fuel cell unit includes a fuel cell stack having a plurality of cells cooled by a refrigerant, a boost converter that boosts and outputs the output voltage of the fuel cell stack, and a case that accommodates the fuel cell stack and the boost converter in the same space, and the boost converter includes a power module, a smoothing capacitor, and a bus bar that electrically connects the power module and the smoothing capacitor, and a heat conductive member is provided to thermally connect the bus bar and the fuel cell stack.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a fuel cell unit.

Background Art

[0002] Patent Document 1 discloses a fuel cell unit having a structure in which a fuel cell stack including a plurality of cells and a boost converter including a smoothing capacitor are housed in the same case. In this fuel cell unit, a plurality of cells are cooled by cooling water flowing through a cooling water flow path provided inside the fuel cell stack. Therefore, in the fuel cell stack, the cells arranged on the inlet side of the cooling water flow path have a lower temperature than the cells arranged on the outlet side of the cooling water flow path. Thus, in this fuel cell unit, among the components constituting the boost converter, components with a low upper heat resistance limit temperature and difficult to cool with water are arranged on the inlet side of the cooling water flow path of the fuel cell stack, so as to suppress an excessive rise in the temperature of those components.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the configuration described in Patent Document 1 protects the smoothing capacitor of the boost converter from the heat released by the fuel cell stack into the case, and does not protect the smoothing capacitor from the heat generated on the boost converter side. Therefore, with the configuration described in Patent Document 1, when the boost converter generates heat, it is impossible to prevent overheating of the smoothing capacitor due to directly receiving heat from the bus bar.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a fuel cell unit capable of preventing overheating of a smoothing capacitor caused by heat generated on the step-up converter side.

Means for Solving the Problems

[0006] The present invention includes a fuel cell stack having a plurality of cells cooled by a refrigerant, a step-up converter that boosts and outputs the output voltage of the fuel cell stack, and a case that houses the fuel cell stack and the step-up converter in the same space. The step-up converter is a fuel cell unit having a power module, a smoothing capacitor, and a bus bar that electrically connects the power module and the smoothing capacitor, and is characterized by including a heat conduction member that thermally connects the bus bar and the fuel cell stack.

[0007] According to this configuration, the heat of the bus bar can be transmitted from the heat conduction member to the fuel cell stack. Thereby, since it can suppress that the heat of a bus bar is transmitted to a smoothing capacitor, the overheat of the smoothing capacitor by the heat generate | occur | produced by the step-up converter side can be prevented.

[0008] Further, the heat conduction member may have a first insulating portion that has insulating properties and contacts the bus bar, and a second insulating portion that has insulating properties and contacts the cell.

[0009] According to this configuration, since the portion in contact with the bus bar and the portion in contact with the cell have insulating properties, it is possible to receive heat from the bus bar and transfer heat to the cell while preventing a short circuit.

[0010] Further, the heat conduction member may have an intermediate portion that is interposed between the first insulating portion and the second insulating portion and is superior in thermal conductivity to the first insulating portion and the second insulating portion.

[0011] According to this configuration, since the intermediate portion has better thermal conductivity than the first insulating portion and the second insulating portion, the thermal resistance of the heat conducting member can be reduced.

Advantages of the Invention

[0012] In the present invention, the heat of the bus bar can be transferred from the heat conducting member to the fuel cell stack. Thereby, it is possible to suppress the heat of the bus bar from being transmitted to the smoothing capacitor, and thus it is possible to prevent the smoothing capacitor from overheating due to the heat generated on the step-up converter side.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0014] Hereinafter, with reference to the drawings, the fuel cell unit according to the embodiment of the present invention will be specifically described. Note that the present invention is not limited to the embodiments described below.

[0015] FIG. 1 is a diagram schematically showing a vehicle equipped with a fuel cell unit according to an embodiment. The fuel cell unit (hereinafter referred to as the FC unit) 1 includes a fuel cell stack (hereinafter referred to as the FC stack) 2 and a step-up converter (hereinafter referred to as the FDC) 3. The FC unit 1 is mounted on a vehicle Ve having a motor (MG) 4 as a power source.

[0016] The vehicle Ve is a fuel cell electric vehicle (FCEV) that drives the motor 4 with the electric power generated by the FC stack 2 and travels with the power output from the motor 4. This vehicle Ve includes an FC unit 1, a motor 4, an inverter (INV) 5, and a battery 6.

[0017] The FC unit 1 is a unit in which the FC stack 2 and the FDC 3 are electrically connected. The FC stack 2 includes a plurality of cells 21 (shown in FIG. 3). The FDC 3 is a boosting device that boosts and outputs the electric power generated by the FC stack 2. The FDC 3 is a DC / DC converter for a fuel cell.

[0018] The motor 4 is a driving motor and is a motor - generator that functions as an electric motor and a generator. This motor 4 is composed of an AC motor. The motor 4 is electrically connected to the FC unit 1 and the battery 6 via the inverter 5. Therefore, when the electric power output from the FC stack 2 is supplied to the motor 4 via the inverter 5, the motor 4 is driven. Alternatively, when the electric power output from the battery 6 is supplied to the motor 4 via the inverter 5, the motor 4 is driven.

[0019] The inverter 5 is a power conversion device that converts DC power into AC power and supplies it to the motor 4. The inverter 5 is electrically connected to the motor 4, the FC unit 1, and the battery 6.

[0020] The battery 6 is a DC power source and is composed of a secondary battery that stores the electric power for supplying to the motor 4. The battery 6 supplies electric power to the motor 4 when the FC stack 2 cannot generate sufficient electric power, and stores the electric power generated by the motor 4 during regeneration. In this case, the electric power output from the battery 6 is supplied to the motor 4 via the inverter 5, and the electric power generated by the motor 4 is supplied to the battery 6 via the inverter 5. Also, the battery 6 is electrically connected to the FC stack 2.

[0021] In the FC stack 2 mounted on the vehicle Ve, the number of cells 21 is reduced in order to achieve cost reduction and miniaturization. In this case, by reducing the number of cells 21, the total voltage of the entire FC stack 2 decreases. Therefore, an FDC 3 is required at the output section of the FC stack 2 in order to raise the output voltage of the FC stack 2 to the required voltage. Further, in order to enable efficient arrangement in the limited space of the vehicle Ve, the FC stack 2 and the FDC 3 are configured as one FC unit 1.

[0022] Here, with reference to FIGS. 2 to 5, the structure of the FC unit 1 will be described.

[0023] As shown in FIGS. 2 and 3, the FC unit 1 has a structure in which the FC stack 2 and the FDC 3 are housed in one case 10. The case 10 houses the FC stack 2 and the FDC 3 in the same space. Inside the case 10, there is no partition wall separating the FC stack 2 and the FDC 3.

[0024] The case 10 is formed including an FC stack case 11 that houses the FC stack 2 and an FDC case 12 that houses the FDC 3. The FC stack case 11 and the FDC case 12 are integrated by bolt fastening or the like. The FC stack case 11 and the FDC case 12 form one internal space without a partition wall.

[0025] In the case 10, the FC stack 2 and the FDC 3 are arranged at positions facing each other in the vertical direction, and the FC stack 2 is arranged above the FDC 3. As shown in FIG. 3, the FC stack 2 is arranged on the upper side of the case 10, and the FDC 3 is arranged on the lower side of the case 10. The FC stack 2 is housed in the common case 10 with the FDC 3 and is arranged at a position close to the ceiling surface of the case 10 above the FDC 3. The FDC 3 is housed in the common case 10 with the FC stack 2 and is arranged at a position close to the lower surface of the cell 21 below the FC stack 2. Note that FIG. 3 schematically shows the structure in the cross section taken along line A-A of FIG. 2.

[0026] The FC stack 2 includes a cell stack 22 in which a plurality of cells 21 are stacked and a pair of terminals 23 and 24.

[0027] The cell stack 22 has a structure in which a plurality of cells 21 are stacked in a predetermined direction. In the cell stack 22, electricity and water are generated by the chemical reaction between hydrogen and oxygen in each cell 21. The cell 21 has a structure in which an MEA (Membrane Electrode Assembly) is sandwiched between a pair of separators, a hydrogen flow path is provided on one side thereof, and an oxygen flow path is provided on the other side thereof. In the cell stack 22, the plurality of cells 21 are cooled by a refrigerant.

[0028] Since a large amount of heat is generated during power generation in the FC stack 2, the refrigerant is circulated during operation to prevent the temperature from exceeding the heat resistance upper limit of the cell 21. When the FC stack 2 is operated, it is always controlled to a temperature with excellent power generation efficiency while suppressing the deterioration of the FC stack 2 by a refrigerant such as cooling water. Specifically, since heat is generated in the cell 21 by the fuel cell reaction during the operation of the FC stack 2, each cell 21 is cooled by the cooling water flowing inside the FC stack 2. The cooling water is, for example, a coolant mainly composed of ethylene glycol. A cooling water flow path through which the cooling water flows is provided inside the FC stack 2. Since the FC stack 2 is cooled from the inside by the cooling water flowing through the cooling water flow path in this way, the temperature rise of the cell 21 is suppressed.

[0029] The pair of terminals 23 and 24 are terminals for extracting the power generated by the fuel cell reaction of each cell 21, and are provided at both ends in the stacking direction of the cell stack 22. The pair of terminals 23 and 24 are composed of a P terminal 23 and an N terminal 24.

[0030] The P terminal 23 is disposed on one side in the stacking direction of the cell stack 22 and has a protruding portion 23a that protrudes toward the FDC3 side from the cell stack 22. The protruding portion 23a of the P terminal 23 is the positive terminal of the FC stack 2. The N terminal 24 is disposed on the other side in the stacking direction of the cell stack 22 and has a protruding portion 24a that protrudes toward the FDC3 side from the cell stack 22. The protruding portion 24a of the N terminal 24 is the negative terminal of the FC stack 2.

[0031] The P terminal 23 electrically connects the positive electrode side of the FC stack 2 and the positive electrode bus bar (P bus bar) 41 on the upstream side of the reactor 31 of the FDC3. The protruding portion 23a of the P terminal 23 and the positive electrode bus bar 41 are connected by bolt fastening or the like. The N terminal 24 electrically connects the negative electrode side of the FC stack 2 and the negative electrode bus bar (N bus bar) 42 on the downstream side of the smoothing capacitor 34 of the FDC3. The protruding portion 24a of the N terminal 24 and the negative electrode bus bar 42 are connected by bolt fastening or the like. In one internal space within the case 10, the FC stack 2 and the FDC3 are directly connected by the positive electrode bus bar 41 and the negative electrode bus bar 42.

[0032] The FDC3 includes a reactor 31, a current sensor 32, a power module (hereinafter referred to as IPM) 33, a smoothing capacitor 34, and a branch BOX and terminal block 35.

[0033] The reactor 31 is provided between the P terminal 23 and the IPM 33. The FDC3 is a multiphase boost converter and includes four reactors 31A to 31D.

[0034] The four reactors 31A to 31D are connected in parallel between the P terminal 23 and the IPM 33. Each of the reactors 31A to 31D is connected in parallel to the P terminal 23 using a bus bar and is also connected in parallel to the IPM 33 using a bus bar. A current sensor 32 is attached to the bus bar connecting each of the reactors 31A to 31D and the IPM 33.

[0035] The current sensor 32 measures the value of the current flowing between the reactor 31 and the IPM 33. For example, the current sensor 32 is constituted by a Hall element type current sensor including a magnetic core through which the bus bar passes and a Hall element inserted into the gap of the magnetic core.

[0036] The IPM 33 is an intelligent power module including a switching element and a diode. When the voltage from the FC stack 2 is input, the switching element of the IPM 33 performs a switching operation so as to periodically repeat the accumulation and discharge of power to the reactor 31 according to the switching control by the control device. The power released from the reactor 31 is output to the smoothing capacitor 34 via the diode of the IPM 33. A bus bar 50 is connected to the output side of the IPM 33.

[0037] The bus bar 50 is a bus bar that electrically connects the IPM 33 and the smoothing capacitor 34. The bus bar 50 is constituted by a P bus bar 51 and an N bus bar 52. The P bus bar 51 and the N bus bar 52 are each connected to the element (capacitor element) of the smoothing capacitor 34. That is, the bus bar 50 is a capacitor bus bar. In this description, when the P bus bar 51 and the N bus bar 52 are not distinguished, it is described as the bus bar 50.

[0038] The smoothing capacitor 34 is a capacitor that smooths the voltage output from the IPM 33. This smoothing capacitor 34 includes a capacitor element. For example, the capacitor element is a plastic film (dielectric film) of a film capacitor.

[0039] Also, the smoothing capacitor 34 is electrically connected to the branch BOX and the terminal block 35 via a bus bar. The N terminal 24 is connected to the smoothing capacitor 34 via the branch BOX and the terminal block 35.

[0040] The branch BOX and the terminal block 35 are components arranged on the downstream side of the smoothing capacitor 34. The branch BOX and the terminal block 35 are electrically connected to the N terminal 24 via the negative electrode bus bar 42. Connected to the branch BOX and the terminal block 35 are the output terminal 61 for the battery provided outside the case 10, the output terminal 62 for the PCU, and the output terminal 63 for the inverter of the air compressor.

[0041] Also, the FDC 3 includes a reactor cooler 71 and an IPM control board 72.

[0042] The reactor cooler 71 is a cooler attached to the lower part of the case 10, and cools the reactor 31 with the cooling water flowing inside. The reactor 31 is water-cooled. The reactor cooler 71 is connected to a cooling circuit in which the cooling water cooled by the radiator circulates. The reactor cooler 71 is attached to the lower part of the FDC case 12.

[0043] The reactors 31A to 31D are attached to the bottom surface of the case 10 corresponding to the position where the reactor cooler 71 is attached. The cooling water supplied to the reactor cooler 71 circulates through the cooling circuit. For example, this cooling circuit includes a pump, a radiator, and the reactor cooler 71. The cooling water pumped by the pump and circulating inside the cooling circuit is cooled by the radiator and then supplied to the reactor cooler 71.

[0044] The IPM control board 72 is a board that controls the switching elements of the IPM 33. The IPM control board 72 is arranged below the IPM 33. Different from other components, the IPM control board 72 is housed in a separate chamber provided outside and below the case 10. A cover 13 for housing the IPM control board 72 is attached to the lower part of the case 10. The cover 13 is attached to the lower part of the FDC case 12 by bolts or the like and integrated with the case 10.

[0045] In the FC unit 1 configured as described above, among the components of the FDC 3, the smoothing capacitor 34 is a component with a particularly low heat-resistant temperature. As shown in FIG. 4, the heat-resistant temperature of the components of the FDC 3 varies depending on the components, but the heat-resistant temperature of the element of the smoothing capacitor 34 is about 105 to 120°C, which is particularly low compared to other components. When the FC stack 2 is operating, the temperature of the cell 21 is about 100°C, and the surface temperature of the FC stack 2 is about 95 to 105°C. Thus, the upper heat-resistant limit temperature of the element of the smoothing capacitor 34 is higher than the temperature of the FC stack 2. In the FC unit 1, each of the FC stack 2 and the FDC 3 is a target of cooling by cooling water. Although the reactor 31 can be water-cooled by cooling water, it is difficult to water-cool the smoothing capacitor 34. Therefore, in the FC unit 1, the smoothing capacitor 34 is configured to be protected from heat.

[0046] As factors for the temperature rise of the smoothing capacitor 34, there are two factors: heat generation of the capacitor element itself and heat transfer from the P bus bar 51 and the N bus bar 52 connected to the capacitor element.

[0047] Regarding the heat generation of the capacitor element itself, which is the first factor, the heat of the smoothing capacitor 34 is configured to be transmitted from the heat dissipation sheet 73 to the case 10. The path through which the heat of the smoothing capacitor 34 is transmitted is in the order of the heat dissipation sheet 73 and the case 10.

[0048] The heat dissipation sheet 73 is interposed between the smoothing capacitor 34 and the FDC case 12. For example, the heat dissipation sheet 73 is sandwiched between the bottom of the smoothing capacitor 34 and the bottom surface of the FDC case 12. The heat dissipation sheet 73 is composed of a heat-conductive member having insulation, such as a silicon-based heat-conductive member.

[0049] When the capacitor element of the smoothing capacitor 34 generates heat, as shown in FIG. 5, the heat of the smoothing capacitor 34 is transmitted to the FDC case 12 via the heat dissipation sheet 73. In this way, the heat of the capacitor element can be released from the heat dissipation sheet 73 to the FDC case 12. As a result, the heat generated in the capacitor element of the smoothing capacitor 34 is transmitted from the heat dissipation sheet 73 to the FDC case 12 and dissipated from the FDC case 12 to the outside of the case 10. Note that FIG. 5 schematically shows an enlarged structure of the portion surrounded by the broken line in FIG. 3.

[0050] Regarding the heat transfer from the P bus bar 51 and the N bus bar 52, which are the second factors, the heat of the bus bar 50 is configured to be transmitted from the heat conduction member 80 to the FC stack 2. Inside the case 10, a heat conduction member 80 is provided as a member for suppressing the heat of the bus bar 50 from being transmitted to the smoothing capacitor 34. In the smoothing capacitor 34, the heat transfer from the P bus bar 51 and the N bus bar 52 is suppressed, thereby suppressing the temperature rise of the capacitor element.

[0051] The heat conduction member 80 is a member that thermally connects the bus bar 50 and the FC stack 2. The heat conduction member 80 is interposed between the bus bar 50 and the FC stack 2. That is, the bus bar 50 connected to the element of the smoothing capacitor 34 and the FC stack 2 are connected by a heat conduction member 80 made of an insulating member having excellent thermal conductivity. Inside the case 10, the heat conduction member 80 forms a heat transfer path for dissipating the heat of the bus bar 50 to the FC stack 2. The path through which the heat of the bus bar 50 is transmitted is in the order of the heat conduction member 80 and the FC stack 2.

[0052] The heat conduction member 80 includes a first insulating portion 81, an intermediate portion 82, and a second insulating portion 83. The heat conduction member 80 is formed in a three-layer structure.

[0053] The first insulating portion 81 has insulation properties and is a portion that contacts the bus bar 50. This first insulating portion 81 forms the first layer of the three-layer structure. The first insulating portion 81 is composed of a silicon-based heat conductive member such as a thermal interface material or a gap filler. This first insulating portion 81 is in surface contact with the surface of the bus bar 50.

[0054] The intermediate portion 82 is interposed between the first insulating portion 81 and the second insulating portion 83 and is a portion having better heat conductivity than the first insulating portion 81 and the second insulating portion 83. This intermediate portion 82 forms the second layer of the three-layer structure. Since insulation is not required for the intermediate portion 82, it is composed of a metal with excellent heat conductivity such as copper or aluminum.

[0055] The second insulating portion 83 has insulation properties and is a portion that contacts the cell 21. This second insulating portion 83 forms the third layer of the three-layer structure. The second insulating portion 83 is composed of a silicon-based heat conductive member such as a thermal interface material or a gap filler. This second insulating portion 83 is in surface contact with the surface of the FC stack 2. Specifically, the second insulating portion 83 is in surface contact with the surface of the cell 21. In this case, the second insulating portion 83 can be configured to be in surface contact with the lower surfaces of a plurality of cells 21. That is, the second insulating portion 83 is configured to be in surface contact with the lower surface of the cell stack 22.

[0056] When the heat of the bus bar 50 is transmitted to the cell 21 through the heat conductive member 50, in the heat conductive member 80, the first insulating portion 81 receives heat from the bus bar 50, and the heat is transmitted from the first insulating portion 81 to the second insulating portion 83 through the intermediate portion 82 and is transferred from the second insulating portion 83 to the cell 21. In the FC stack 2, since each cell 21 is cooled by cooling water, the temperature rise of the cell 21 is suppressed. Furthermore, since the FC stack 2 has the cell stack 22, it has a large heat capacity. Therefore, the heat of the bus bar 50 can be radiated (heat transferred) from the heat conductive member 80 to the cell 21 of the FC stack 2.

[0057] The heat conduction member 80 configured as described above is provided on both the P bus bar 51 and the N bus bar 52. For example, the heat conduction member 80 includes two members, a first heat conduction member interposed between the P bus bar 51 and the cell 21, and a second heat conduction member interposed between the N bus bar 52 and the cell 21. In this case, the first insulating portion 81 of the first heat conduction member is in surface contact with the surface of the P bus bar 51. The first insulating portion 81 of the second heat conduction member is in surface contact with the surface of the N bus bar 52. Then, the heat of the P bus bar 51 is transmitted to the cell 21 through the first heat conduction member. The heat of the N bus bar 52 is transmitted to the cell 21 through the second heat conduction member.

[0058] Under the condition that the bus bar 50 becomes high temperature, as shown in FIG. 5, the heat of the bus bar 50 is transmitted to the FC stack 2 through the heat conduction member 80. In this way, the heat of the bus bar 50 can be released from the heat conduction member 80 to the FC stack 2. As a result, the inflow of heat from the bus bar 50 to the smoothing capacitor 34 can be prevented.

[0059] Generally, the upper heat resistance limit temperature of the elements of the smoothing capacitor 53 is about 120°C. On the other hand, since the cell 21 of the FC stack 2 is cooled by cooling water, its temperature (cell temperature) is about 100°C. When the temperature of the bus bar 50 exceeds the upper heat resistance limit temperature of the capacitor elements of the smoothing capacitor 34, the heat of the bus bar 50 flows from the heat conduction member 80 to the FC stack 2 side, so the inflow of heat from the bus bar 50 to the capacitor elements can be suppressed. Thereby, the heat of the bus bar 50 can be released to the FC stack 2, and the inflow of heat to the smoothing capacitor 34 can be prevented.

[0060] As described above, according to the embodiment, in the FC unit 1 having a structure in which the FC stack 2 and the FDC 3 are integrated, the bus bar 50 and the FC stack 2 are thermally connected by the heat conducting member 80 within the case 10 that houses them. When the FC stack 2 is operating, since the temperature of the cell 21 is lower than the heat resistance upper limit temperature of the element of the smoothing capacitor 34, when the temperature of the bus bar 50 exceeds the heat resistance upper limit temperature of the capacitor element, the heat of the bus bar 50 flows toward the FC stack 2 side, so that the inflow of heat into the capacitor element can be suppressed. Thereby, it is possible to suppress the element of the smoothing capacitor 34 from directly receiving heat from the bus bar 50, and it is possible to prevent overheating of the smoothing capacitor 34 due to the heat generated on the FDC 3 side.

[0061] Also, although the structure in which the FDC 3 is disposed below the FC stack 2 has been described, the present invention is not limited thereto. The FDC 3 may be disposed above, below, to the left, or to the right of the FC stack 2. As an example of a modification, in the case of a structure in which the FDC 3 is disposed above the FC stack 2, it is possible to adopt a structure in which the arrangement in FIG. 3 is reversed vertically (the arrangement obtained by rotating FIG. 3 180 degrees clockwise on the paper surface). Alternatively, in the case of a structure in which the FDC 3 is disposed to the left of the FC stack 2, it is possible to adopt an arrangement obtained by rotating FIG. 3 90 degrees clockwise on the paper surface. Or, in the case of a structure in which the FDC 3 is disposed to the right of the FC stack 2, it is possible to adopt an arrangement obtained by rotating FIG. 3 90 degrees counterclockwise on the paper surface.

[0062] Also, the heat conducting member 80 is not limited to a three-layer structure including the first insulating portion 81, the intermediate portion 82, and the second insulating portion 83. The heat conducting member 80 may be entirely composed of an insulating member having insulating properties. That is, the heat conducting member 80 may be a single-layer structure composed of a member having excellent heat conductivity and insulating properties. When comparing the heat conductivity of the heat conducting member 80 having this three-layer structure and the heat conducting member 80 having a single-layer structure, the three-layer structure is superior in heat conductivity because the heat resistance is smaller by the amount of the intermediate portion 82.

[0063] Further, the heat conduction member 80 is not limited to a configuration in which one heat conduction member is provided for each of the P bus bar 51 and the N bus bar 52 (a configuration including a first heat conduction member and a second heat conduction member). The number of heat conduction members 80 is not limited. For example, a configuration in which one heat conduction member 80 is in surface contact with the P bus bar 51 and the N bus bar 52 may be used.

[0064] Regarding the power supply circuit mounted on the vehicle Ve, a boost converter (BDC) may be provided between the battery 6 and the inverter 5.

Explanation of Signs

[0065] 1 Fuel cell unit (FC unit) 2 Fuel cell stack (FC stack) 3 Boost converter (FDC) 4 Motor 5 Inverter 6 Battery 10 Case 11 FC stack case 12 FDC case 21 Cell 22 Cell laminate 23 P terminal 23a Protrusion 24 N terminal 24a Protrusion 31, 31A, 31B, 31C, 31D Reactor 32 Current sensor 33 Power module (IPM) 34 Smoothing capacitor 35 Branch BOX and terminal block 41 Positive electrode bus bar 42 Negative electrode bus bar 50 Bus bar 51 P bus bar 52 N bus bar 80 Heat conduction member 81 First insulating part 82 Intermediate part 83 Second insulating part

Claims

1. A fuel cell stack having a plurality of cells cooled by a refrigerant, A boost converter that boosts and outputs the output voltage of the fuel cell stack, A case that houses the fuel cell stack and the boost converter in the same space, and comprising The boost converter is a fuel cell unit having a power module, a smoothing capacitor, and a bus bar that electrically connects the power module and the smoothing capacitor, and comprising a heat conduction member that thermally connects the bus bar and the fuel cell stack A fuel cell unit characterized by this.

2. The heat conduction member has insulation and has a first insulating portion that contacts the bus bar, has insulation and has a second insulating portion that contacts the cell, The fuel cell unit according to claim 1, characterized by this.

3. The heat conduction member has an intermediate portion that is interposed between the first insulating portion and the second insulating portion and is superior in thermal conductivity to the first insulating portion and the second insulating portion The fuel cell unit according to claim 2, characterized by this.

Images