Busbar arrangement for a fuel cell power converter

Abstract

A busbar assembly for a fuel cell stack and a fuel cell system is provided. The busbar assembly comprises a positive busbar, a negative busbar, and an insulating layer. The positive busbar is made of aluminum and features a positive fuel cell connection end, a positive module end, and a positive heat sink tab located between the positive fuel cell connection end and the positive module end. The positive heat sink tab is offset from the positive electrical current path. The negative busbar is also made of aluminum and features a negative fuel cell connection end, a negative module end, and a negative heat sink tab located between the negative fuel cell connection end and the negative module end. The negative heat sink tab is offset from the negative electrical current path.

Description

[0001] The present invention relates to a fuel cell system and in particular a busbar arrangement for use at an interface between a fuel cell stack and a power control sensing module.

[0002] Fuel cell systems feature a fuel cell stack that generates electrical energy. The fuel cell stack, which consists of multiple fuel cells connected in series, produces electrical power through electrochemical reactions between a hydrogen-based feed gas (e.g., pure hydrogen or hydrogen reformate) and an oxidant feed gas (e.g., pure oxygen or oxygenated air). The power converter and sensing module (PCSM) is a critical component that manages the distribution and control of the electrical power generated by the fuel cell stack.

[0003] DE 21 2019 000 283 U1 describes a busbar comprising a first end, a second end and a conductive path provided between the first and second ends; the conductive path includes at least one projection configured and dimensioned to be connected to a cooling element.

[0004] The object of the invention is achieved by means of a busbar arrangement for a fuel cell stack. The busbar arrangement comprises a positive busbar configured to carry a positive electrical current, a negative busbar configured to carry a negative electrical current, and an insulating layer arranged between the positive and negative busbars. The positive busbar is formed from at least one aluminum or an aluminum alloy and has a positive fuel cell terminal end, a positive module end distal to the positive fuel cell terminal end, and a positive heat sink tab arranged between the positive fuel cell terminal end and the positive module end. A positive electrical current path is defined between the positive fuel cell terminal end and the positive module end.The positive heat sink tab is offset from the positive electrical current path. The negative busbar is formed from at least one aluminum or aluminum alloy component and has a negative fuel cell terminal end, a negative module end distal to the negative fuel cell terminal end, and a negative heat sink tab located between the negative fuel cell terminal end and the negative module end. A negative electrical current path is defined between the negative fuel cell terminal end and the negative module end. The negative heat sink tab is offset from the negative electrical current path and is aligned with the positive heat sink tab.The positive busbar features a positive stepped section located between the positive fuel cell terminal end and the positive module end, and positioned close to the positive module end. The positive stepped section is configured to dissipate heat.

[0005] According to one embodiment, the busbar arrangement is configured to carry an electric current of 800 amperes.

[0006] According to another embodiment, the busbar arrangement is configured to transfer less than five watts of heat to a power converter and sensing module (PCSM).

[0007] According to another embodiment, the positive busbar and the negative busbar are made of electrical conductor grade aluminum, EC-aluminium.

[0008] According to another embodiment, the positive busbar and the negative busbar have a coating of at least one of tin, Sn, nickel, Ni, silver, Ag or a silver alloy.

[0009] According to another embodiment, the positive busbar has a plurality of positive cylindrical cutouts which at least partially define the positive heat sink tab and are configured to direct the electric current away from the positive heat sink tab.

[0010] According to another embodiment, the negative busbar has a negative stepped section located between the negative end of the fuel cell connector and the negative end of the module, and positioned near the negative end of the module. The negative stepped section is configured to dissipate heat.

[0011] According to another embodiment, the negative busbar has a plurality of negative cylindrical cutouts that at least partially define the negative heat sink tab and are configured to direct the electrical current away from the negative heat sink tab.

[0012] According to another embodiment, the insulating layer comprises at least one of an elastomer, a polymer, polytetrafluoroethylene, PTFE, an enamel, a resin coating or a polyimide tape.

[0013] According to another embodiment, the insulating layer has at least one insulating insert or spacer for selective insulation.

[0014] In one application, a vehicle is provided with a fuel cell system. The vehicle with a fuel cell system has a fuel cell stack with a housing, a power converter and a sensing module (PCSM) which are positioned offset from and rotated around the fuel cell stack, and a busbar arrangement according to the invention and its embodiments, which is arranged at an interface between the fuel cell stack and the power converter and the sensing module (PCSM).

[0015] The above-mentioned features and advantages, as well as other features and advantages of the system and method described herein, are readily apparent from the detailed description, including the claims and examples, in conjunction with the accompanying drawings.

[0016] The present description will be better understood through the detailed description and the accompanying drawings. Fig. Figure 1 is a perspective view illustrating an example of a vehicle with an electric motor powered by a fuel cell stack with a busbar arrangement. Fig. Figure 2 is an isometric view of a fuel cell stack and a power control sensing module in which the Fig. 1 vehicle shown. Fig. 3 is a top view of the busbar arrangement in the Fig. 2 fuel cell stacks shown. Fig. 4 is an isometric view of the Fig. 3 busbar arrangement shown. Fig. 5 is a top view of a positive busbar in the Fig. 3 and Fig. 4 busbar arrangement shown. Fig. 6 is a top view of a negative busbar in the Fig. 3 and Fig. 4 busbar arrangement shown.

[0017] The following description is merely exemplary. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding introduction, summary, or the subsequent detailed description. It is understood that in the drawings, identical reference symbols denote identical or corresponding parts and features.

[0018] Several examples of the description, illustrated in the accompanying drawings, will now be discussed in detail. Where possible, the same or similar reference symbols are used in the drawings and the description to refer to identical or similar parts or steps. The drawings are simplified and not to scale. The following description is merely exemplary and is not intended to limit the present description, application, or uses.

[0019] Busbars are conductive rods used to distribute electrical power within the fuel cell stack and between the stack and the power converter and sensing module (PCSM). However, conventional busbar arrangements can have limitations in their ability to dissipate heat effectively, especially when positioned between the fuel cell stack and the PCSM without active cooling. Small amounts of heat generated due to ohmic losses significantly increase temperatures near the busbars. Heat entering the PCSM is also critical and can affect the functionality of sensing, monitoring, and measuring devices within the PCSM. This can lead to hotspots, thermal stress, and uneven temperature distribution, which can negatively impact the performance and durability of the fuel cell system.

[0020] The busbar arrangement described herein addresses these problems by providing a busbar configuration for improved heat dissipation. The busbar arrangement optimizes thermal management and heat dissipation, ensuring that heat generated within the fuel cell stack is efficiently transferred away from critical components. By incorporating structural modifications, the proposed busbar arrangement improves the overall thermal performance of the fuel cell system, contributing to increased efficiency, reliability, and safety.

[0021] With reference to Fig. Figure 1 is a perspective view of a vehicle 10 with a fuel cell stack 12, a power converter and a data acquisition module (PCSM) 14, and a vehicle battery pack 16 as described herein. The fuel cell stack 12, the PCSM 14, and the battery pack 16 are illustrated with an exemplary vehicle 10. The vehicle 10 can be an electric vehicle or a hybrid vehicle with wheels 18, driven by at least one electric motor / inverter (not shown). The electric motors / inverters receive power from the battery pack 16, which receives electricity from the fuel cell stack 12. Although the vehicle 10 is illustrated as a passenger car, it is understood that the fuel cell stack 12 and the battery pack 16 can be used with various other types of vehicles.For example, the fuel cell stack 12 and the battery pack 16 can be used in watercraft, such as boats, or aircraft, such as drones or passenger planes. The vehicle 10 can be a fuel cell-based hybrid / electric vehicle, for example, a truck, an all-terrain vehicle, or a vehicle configured to transport people or goods. Furthermore, the fuel cell stack 12 and the battery pack 16 can be used as a stationary power source that is separate and independent from a vehicle.

[0022] As used herein, the term "vehicle" is not limited to motor vehicles. Although the technology presented here is mainly described in connection with electric and hybrid electric vehicles, the technology is not limited to electric and hybrid electric vehicles.The concepts can be used in a wide variety of applications, such as in conjunction with components used in motorcycles, mopeds, locomotives, aircraft, watercraft, and other vehicles, as well as in other battery-powered applications, such as portable power plants used to power remote construction sites, emergency power supplies, and permanent power plants connected to buildings and equipment, all of which can be driven, for example, by solar- or wind-powered generator systems, power grids, and fuel-based power generators such as gasoline, propane, kerosene, or diesel generators, as well as Sterling engines.

[0023] Fig. 2 illustrates the in Fig. Figure 1 illustrates a fuel cell stack 12. The fuel cell stack 12 generates electrical power. The fuel cell stack 12 has a housing 20 and comprises several individual fuel cells arranged in series, each cell containing an anode (not shown), a cathode (not shown), and a proton exchange membrane (PEM) or polymer electrolyte membrane (PEM) (not shown) between the anode and the cathode. Hydrogen is fed into the anode side, where the hydrogen splits into protons and electrons. The protons pass through the membrane to the cathode, while the electrons move through an external circuit, generating an electric current. At the cathode, the protons, electrons, and oxygen from the air combine to form water and release heat.

[0024] Fig. Figure 2 illustrates the PCSM 14 coupled to the fuel cell stack 12. The PCSM 14 monitors and controls various components of a fuel cell system and the fuel cell stack 12, including a hydrogen gas injection device, an electric air compressor, a circulation pump, and sensors, none of which are shown. The PCSM 14 ensures that the fuel cell stack 12 provides the required amount of electrical power based on demand. The PCSM may include a power electronics device that senses fuel cell voltages, measures currents, and / or acts as a converter. As shown in Figure 2, the PCSM 14 monitors and controls various components of a fuel cell system and the fuel cell stack 12, including a hydrogen gas injection device, an electric air compressor, a circulation pump, and sensors, none of which are shown. The PCSM 14 ensures that the fuel cell stack 12 provides the required amount of electrical power based on demand. The PCSM may include a power electronics device that senses fuel cell voltages, measures currents, and / or acts as a converter. Fig. As shown in Figure 2, the PCSM 14 can be coupled to the fuel cell stack 12 in an offset and rotated configuration (e.g., the PCSM 14 is not coupled to the fuel cell stack 12 on a first side 22 or the top end). The PCSM 14 can be offset and rotated around the fuel cell stack 12 to minimize the height of the combined fuel cell stack 12 and PCSM 14.

[0025] With reference to Fig. Figure 3 illustrates a busbar assembly 24 at an interface 26 between the fuel cell stack 12 and the PCSM 14. The busbar assembly 24 acts as a high-current conductor and efficiently transfers electrical power generated by the fuel cell stack 12 to the PCSM 14 via a positive terminal 28 and a negative terminal 30 of the fuel cell stack 12. The busbar assembly 24 electrically couples the positive terminal 28 and the negative terminal 30 of the fuel cell stack 12 to corresponding terminals on the PCSM 14. In one example, the busbar assembly 24 is configured to carry an electrical current of approximately 800 amperes (A). In this context, the term "approximately" is understood by a person skilled in the art. Alternatively, the term "approximately" means plus or minus 5 amperes (A).In another example, the busbar assembly 24 is configured to transfer less than five watts (W) of heat to the PCSM 14. In this context, the term "approximately" is understood by a person skilled in the art. Alternatively, the term "approximately" means plus or minus 0.5 W. It is understood that the busbar assembly 24 may have other configurations and may be configured to carry or transfer other amounts of electrical current. The busbar assembly 24 may be located within a housing of the fuel cell stack 12 and may be far from an active cooling mechanism. Thus, a small amount of heat generated due to ohmic losses significantly increases the temperature near the busbar assembly 24.

[0026] As in the Fig. 3 and Fig. As illustrated in Figure 4, the busbar arrangement 24 has a positive busbar 32, a negative busbar 34, and an insulating layer 36. As illustrated, the positive busbar 32 is configured to overlap the negative busbar 34 with the insulating layer 36 positioned between the positive busbar 32 and the negative busbar 34. However, it is understood that the positive busbar 32 and the negative busbar 34 do not necessarily overlap and can have other configurations.

[0027] The positive busbar 32 has a positive fuel cell terminal 38, a positive module end 40, and a positive heat sink lug 42. The positive busbar 32 can be made of aluminum or an aluminum alloy, preferably electrically conductive aluminum (EC aluminum). The positive fuel cell terminal 38 can be configured to carry a positive electrical current from the fuel cell stack 12 and is electrically coupled to the positive terminal 28 of the fuel cell stack 12. The positive module end 40 is configured to carry the positive electrical current to the PCSM 14 and is electrically coupled to the PCSM 14. A positive current path 44 is defined between the positive fuel cell terminal 38 and the positive module end 40, through which positive electrical current generally flows.

[0028] The Fig. Figures 3-5 illustrate the positive heat sink tab 42. The positive heat sink tab 42 extends from a section of the positive busbar 32 that has the positive current path 44. The positive heat sink tab 42 can be configured as a tab, a flap, an extension, a projection, and / or a section of the positive busbar 32 that extends away from or is located away from the positive current path 44. In the Fig. In the illustrated example 5, the positive heat sink tab 42 is configured as a tab. The positive heat sink tab 42 is configured to dissipate heat from the positive busbar 32 and the busbar assembly 24.

[0029] In the Fig. 4 and Fig. In the example shown in Figure 5, the positive busbar 32 has a positively stepped section 46. The positively stepped section 46 has a series of steps, ribs, corrugations, grooves, and / or channels configured at least to dissipate heat from the positive busbar 32 and the busbar assembly 24. The positively stepped section 46 is located at one position on the positive busbar 32 within a section of the positive current path 44, although the positively stepped section 46 may be located at other positions on the positive busbar 32.

[0030] With reference to the Fig. 3-5 The positive busbar 32 has at least one positive cylindrical cutout 48. Each positive cylindrical cutout 48 can have a partial cutout of a section of the positive busbar 32 close to or near the positive heat sink lug 42. In the Fig. In the illustrated example 5, two positive cylindrical cutouts 48A, 48B are shown on distal sides of the positive heat sink tab 42. These positive cylindrical cutouts 48A, 48B can be configured to conduct passive positive electric current along the positive current path 44 and away from the positive heat sink tab 42. Each positive cylindrical cutout 48 serves to prevent or minimize heat generation within the positive heat sink tab 42. It is understood that each positive cylindrical cutout 48 may have different locations or configurations than those shown in the Fig. 3-5 can be shown.

[0031] With reference to the Fig. 3-4 and Fig. 6 The negative busbar 34 has a negative fuel cell connection end 50, a negative module end 52 and a negative heat sink lug 54. In the Fig. 3-4 and Fig. In the six examples shown, the negative busbar 34 can be configured as a mirror image of the positive busbar 32, although the negative busbar 34 can have other configurations. The negative busbar 34 can be made of aluminum or an aluminum alloy, preferably electrically conductive aluminum (EC aluminum). The negative fuel cell terminal end 50 is configured to carry a negative electrical current from the fuel cell stack 12 and is electrically coupled to the negative terminal 30 of the fuel cell stack 12. The negative module end 52 is configured to carry the negative electrical current to the PCSM 14 and is electrically coupled to the PCSM 14. A negative current path 56 is defined between the negative fuel cell terminal end 50 and the negative module end 52, through which negative electrical current flows.

[0032] The Fig. 3-4 and Fig. Figure 6 illustrates the negative heat sink tab 54. The negative heat sink tab 54 extends from a section of the negative busbar 34 that has the negative current path 56. The negative heat sink tab 54 can be configured as a tab, a flap, an extension, a projection, and / or a section of the negative busbar 34 that extends away from or is located away from the negative current path 56. In the Fig. In the illustrated example 6, the negative heat sink tab 54 is configured as a tab. The negative heat sink tab 54 is configured to dissipate heat from the negative busbar 34 and the busbar assembly 24.

[0033] In the Fig. 4 and Fig. In the example shown in Figure 6, the negative busbar 34 has a negatively stepped section 58. The negatively stepped section 58 has a series of steps, ribs, corrugations, grooves, and / or channels configured at least to dissipate heat from the negative busbar 34 and the busbar assembly 24. The negatively stepped section 58 is located on a section of the negative busbar 34 within a section of the negative current path 56, although the negatively stepped section 58 may be located at other locations on the negative busbar 34.

[0034] With reference to the Fig. 3-4 and Fig. 6 The negative busbar 34 has at least one negative cylindrical cutout 60. Each negative cylindrical cutout 60 can have a partial cutout of a section of the negative busbar 34 close to or near the negative heat sink lug 54. In the Fig. In the illustrated example 6, two negative cylindrical cutouts 60A, 60B are shown on distal sides of the negative heat sink tab 54. These negative cylindrical cutouts 60A, 60B can be configured to conduct passive negative electrical current along the negative current path 56 and away from the negative heat sink tab 54. Each negative cylindrical cutout 60 serves to prevent or minimize heat generation within the negative heat sink tab 54. It is understood that each negative cylindrical cutout 60 may have different locations or configurations than those shown in the Fig. 3-4 and Fig. 6 shown.

[0035] The positive busbar 32 and / or the negative busbar 34 may have a coating 62. The coating 62 may serve to improve corrosion resistance, prevent or eliminate oxidation, and improve contact surfaces. Some examples of the coating 62 may be tin (Sn), nickel (Ni), silver (Ag), and / or a silver alloy. It is understood that the coating 62 may have other materials, compositions, or formulations suitable for coating the positive busbar 32 and / or the negative busbar 34.

[0036] With reference to Fig.Figure 4 shows that the busbar assembly 24 has an insulating layer 36 arranged between the positive busbar 32 and the negative busbar 34. The insulating layer 36 is configured to prevent electrical current from leaking from each busbar and contacting other conductive materials. The insulating layer 36 can be arranged over all or part of the area between the positive busbar 32 and the negative busbar 34, or it can be in the form of inserts or spacers between the positive busbar 32 and the negative busbar 34 for selective insulation. In some examples, the insulating layer 36 can be formed from an elastomer, a polymer, polytetrafluoroethylene (PTFE), an enamel, a resin coating, and / or a polyimide tape.

[0037] In a specific example, the positive busbar 32 is configured to carry a positive electrical current of about 800 amperes (A) and heat of less than 5 watts (W). In this example, the positive heat sink lug 42 has a width of about 100 millimeters (mm), a length of about 60 mm, and a thickness of about 10 mm. In this context, the term "about" is understood by a person skilled in the art. Alternatively, the term "about" is defined as plus or minus 10 mm for the width and length and plus or minus 2 mm for the thickness. The negative busbar 34 and the negative heat sink lug 54 may have similar dimensions. It is understood that the positive busbar 32, the positive heat sink lug 42, the negative busbar 34, and the negative heat sink lug 54 may have other configurations.

[0038] The busbar assembly 24 of this description is advantageous and beneficial compared to the prior art. By using aluminum, the busbar assembly 24 benefits from weight and cost reductions, as well as a negligible change in voltage drop and ohmic losses compared to conventional copper busbars. Reducing the voltage drop and ohmic losses controls heat generation within the busbar assembly 24. Aluminum is less thermally conductive than copper and thus limits the flow of ohmic heat towards the PCSM. Additionally, the busbar assembly 24 benefits from improved cooling performance due to the offset of the positive heat sink lug 42 and the negative heat sink lug 54 from the electrical current path, and due to the effective dissipation of any heat generated.Furthermore, the busbar arrangement 24 is designed to direct the electrical currents away from the positive heat sink lug 42 and the negative heat sink lug 54, which further reduces heat generation and aids heat dissipation.

Claims

[1] Busbar arrangement (24) for a fuel cell stack (12), comprising: a positive busbar (32) configured to carry a positive electric current, wherein the positive busbar (32) is formed from at least one of aluminium or an aluminium alloy and has the following features: a positive fuel cell connection end (38); a positive module end (40) distal to the positive fuel cell terminal end (38), wherein a positive electrical current path (44) is defined between the positive fuel cell terminal end (38) and the positive module end (40); and a positive heat sink tab (42) arranged between the positive fuel cell connection end (38) and the positive module end (40), wherein the positive heat sink tab (42) is offset from the positive electrical current path (44); a negative busbar (34) configured to carry a negative electric current, wherein the negative busbar (34) is formed from at least one of aluminium or an aluminium alloy and has the following features: a negative fuel cell terminal end (50); a negative module end (52) distal to the negative fuel cell terminal end (50), wherein a negative electrical current path (56) is defined between the negative fuel cell terminal end (50) and the negative module end (52); and a negative heat sink tab (54) arranged between the negative fuel cell connection end (50) and the negative module end (52), wherein the negative heat sink tab (54) is offset from the negative electrical current path (56), wherein the negative heat sink tab (54) is aligned with the positive heat sink tab (42); an insulating layer arranged between the positive busbar (32) and the negative busbar (34); and wherein the positive busbar (32) has a positive stepped section (46) which is located between the positive fuel cell connection end (38) and the positive module end (40) and is located near the positive module end (40), and wherein the positive stepped section (46) is configured to dissipate heat. [2] Busbar assembly (24) according to claim 1, wherein the busbar assembly (24) is configured to carry an electric current of 800 amperes. [3] Busbar assembly (24) according to claim 1, wherein the busbar assembly (24) is configured to transfer less than five watts of heat to a power converter and sensing module, PCSM, (14). [4] Busbar arrangement (24) according to claim 1, wherein the positive busbar (32) and the negative busbar (34) are made of electrical conductor grade aluminum, EC-aluminium. [5] Busbar arrangement (24) according to claim 1, wherein the positive busbar (32) and the negative busbar (34) have a coating of at least one of tin, Sn, nickel, Ni, silver, Ag or a silver alloy. [6] Busbar arrangement (24) according to claim 1, wherein the positive busbar (32) has a plurality of positive cylindrical cutouts (48A) which at least partially define the positive heat sink tab (42) and are configured to direct the electric current away from the positive heat sink tab (42). [7] Busbar arrangement (24) according to claim 1, wherein the negative busbar (34) has a negative stepped section (58) which is arranged between the negative fuel cell connection end (50) and the negative module end (52) and is located near the negative module end (52), and wherein the negative stepped section (58) is configured to dissipate heat. [8] Busbar arrangement (24) according to claim 1, wherein the negative busbar (34) has a plurality of negative cylindrical cutouts (60A) which at least partially define the negative heat sink tab (54) and are configured to direct the electric current away from the negative heat sink tab (54), wherein the negative cylindrical cutouts (60A) are aligned with the positive cylindrical cutouts (48A). [9] Busbar arrangement (24) according to claim 1, wherein the insulating layer comprises at least one of an elastomer, a polymer, polytetrafluoroethylene, PTFE, an enamel, a resin coating or a polyimide tape.

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