Selective isolation of a device for monitoring and controlling a fuel cell stack

Abstract

A fuel cell system comprises a housing, a fuel cell within the housing, and a monitoring and control device mounted on the housing. The monitoring and control device includes an enclosure and a cover coupled to the enclosure, forming a cavity. The cover defines an inner cover surface. The inner cover surface partially bounds the cavity. The monitoring and control device also includes a metal-oxide-semiconductor field-effect transistor (MOSFET) located in the cavity between the enclosure and the cover. The inner cover surface of the cover faces the MOSFET. The MOSFET comprises a body and one or more pins extending from the body. The system also includes an electrical insulator coupled to the inner cover surface.The electrical insulator defines an inner insulator surface facing the MOSFET. The pin is spaced away from the electrical insulator to form an air gap.

Description

introduction

[0001] The present description relates to a selective insulation for a device for monitoring and controlling a fuel cell stack.

[0002] This introduction provides a general context for the description. The work of the inventors mentioned herein, insofar as it is described in this introduction, as well as aspects of the description that were not part of the prior art at the time of filing, are neither expressly nor implicitly recognized as prior art in relation to this description.

[0003] Some vehicle systems use fuel cell systems for propulsion. Fuel cell systems include a stack monitoring and control device (SMCD). The SMCD comprises a circuit board, sensors, busbars, a cooling plate, and power electronics, all housed in an enclosure. The SMCD is mounted on the stack enclosure within a fuel cell power module. Some of the enclosure's key functions are preventing accidental access to the power path, protecting the electronics, providing electrical insulation for the components, shielding against external intrusion, and transferring heat to the low-temperature coolant circuit. To meet grounding requirements, the SMCD enclosure should be electrically connected to the vehicle's chassis.

[0004] For a high-voltage clearance, the length of the air gap between an electrical conductor (for example, the MOSFET pin) and the SMCD cover should be greater than 3.0 mm. It is therefore desirable to develop a system that electrically isolates the SMCD cover from a high-voltage electrical conductor, such as the MOSFET pin. Description

[0005] This description describes a fuel cell system. In one aspect of this description, the fuel cell system comprises a housing, a large number of individual fuel cells stacked within the housing, and a stack monitoring and control device mounted on the housing. The stack monitoring and control device comprises an enclosure and a cover coupled to the enclosure to define a cavity. The cover defines an inner cover surface. The inner cover surface partially defines the cavity. The stack monitoring and control device also includes an electronic component, such as a metal-oxide-semiconductor field-effect transistor (MOSFET), located in the cavity between the enclosure and the cover. The inner cover surface of the cover faces the electronic component.The electronic component comprises a body (for example, a p-type substrate) and one or more pins protruding from the body. The system also includes an electrical insulator coupled to the inner cover surface. The electrical insulator defines an inner insulator surface facing the electronic component. The pin is spaced from the electrical insulator to form an air gap.

[0006] In one aspect of this description, the electrical insulator is positioned over the pin of the MOSFET. The electrical insulator can be made entirely of polytetrafluoroethylene (PTFE). The cover and the housing can each be made entirely of a metallic material. The cover defines a recess that is at least partially defined by the inner cover surface. The electrical insulator can be fully positioned within the recess. The inner insulator surface can be flush with the inner cover surface. The air gap has a length defined from the pin to the inner insulator surface. The gap length is greater than 3.0 millimeters, for example, 3.1 millimeters. The electrical insulator has an insulator thickness. The insulator thickness is between 0.2 millimeters and 1 millimeter, for example, 0.3 millimeters. The electrical insulator has a dielectric strength.The dielectric strength of the electrical insulator ranges from 9 kV / mm to 280 kV / mm, for example, 9 kV / mm. The electrical insulator can be made partially or entirely of a ceramic and / or polymeric material, for example, polytetrafluoroethylene (PTFE). The electrical insulator can be completely enclosed within the recess. The cover can be made entirely or partially of an aluminum alloy. The electrical insulator can be made entirely or partially of an elastomer and / or a glass-like enamel.

[0007] The inner cover surface has an inclined and a horizontal surface section. The horizontal surface section is elongated along a horizontal direction. The horizontal direction is perpendicular to a vertical direction, V. The MOSFET pin is spaced from the electrical insulator along the vertical direction. The inclined surface section is angled obliquely relative to the horizontal surface section. The gap length is defined from the MOSFET pin to the inner insulator surface of the electrical insulator along a longitudinal axis. The longitudinal axis intersects the inclined surface section at a perpendicular angle. The gap length is parallel to the longitudinal axis. An oblique angle, for example 37 degrees, is defined between the vertical direction V and the longitudinal axis.

[0008] Further applications of this disclosure will become apparent from the detailed description below. It is understood that the detailed description and specific examples serve only for illustration and are not intended to limit the scope of the disclosure.

[0009] The above features and advantages, as well as other features and advantages of the presently disclosed system and method, are readily apparent from the detailed description, including the claims, and the exemplary embodiments in conjunction with the accompanying drawings. Brief description of the drawings

[0010] The present disclosure will be better understood with the help of the detailed description and the accompanying drawings, whereby: Fig. 1 is a schematic representation of a vehicle with a fuel cell system. Fig. 2 a schematic isometric view of the fuel cell system of Fig. 1, wherein the fuel cell system comprises a stack monitoring and control device (SMCD). Fig. 3 a schematic underside view of the SMCD cover of Fig. 2 is. Fig. 4. An enlarged view of the underside of the SMCD cover. Fig. 3, taken around area A of Fig. 3, is. Fig. 5 a schematic cross-sectional view of the SMCD of Fig. 2, which run along the intersection line 5-5 of Fig. 2 was recorded. Fig. 6 a schematic, enlarged cross-sectional view of the SMCD of Fig. 2, taken around area B of Fig. 5, is. Detailed description

[0011] The following section refers in detail to several examples of the description, which are illustrated in the accompanying drawings. Wherever possible, the same or similar reference numbers are used in the drawings and the description to indicate identical or similar parts or steps.

[0012] In relation to Fig. The vehicle 10 generally comprises a vehicle body 12 and a plurality of wheels 14 coupled to the vehicle body 12. The vehicle 10 may be an autonomous vehicle. In the illustrated embodiment, the vehicle 10 may be a sedan, a truck, a coupé, a sport utility vehicle (SUV), or a recreational vehicle (RV). The vehicle 10 further comprises an electric motor 16 coupled to one or more of the wheels 14. The electric motor 16 is configured to convert electrical energy into mechanical energy (for example, torque) to drive the wheels 14. The vehicle 10 further comprises a fuel cell system 18 electrically connected to the electric motor 16. The fuel cell system 18 is configured to generate electricity from hydrogen or other fuels. Therefore, the fuel cell system 18 supplies the electric motor 16 with power.The fuel cell system 18 comprises a housing 20 and one or more fuel cells 22 inside the housing 20.

[0013] As from the Fig.As shown in Figures 2-6, the fuel cell system 18 comprises a stack monitoring and control device (SMCD) 24 mounted on the housing 20. The SMCD 24 includes an enclosure 26 and a cover 28, which is directly coupled to the enclosure 26. One or more gaskets 30 seal the enclosure 26 and the cover 28. The enclosure 26 and the cover 28 together form a cavity 32. The SMCD 24 houses a circuit board, sensors, busbars, a cooling plate, and power electronic devices in the cavity 32. The cover 28 and the enclosure 26 are each made partially or entirely of a metallic material to enhance the structural integrity of the SMCD 24. For example, the cover 28 may be made partially or entirely of an aluminum alloy.

[0014] The SMCD 24 contains an electronic component, such as a metal-oxide-semiconductor field-effect transistor (MOSFET) 34, a switch, a relay, a capacitor, etc., in the cavity 32 between the housing 26 and the cover 28. The MOSFET 34 or other electronic component comprises a body 36 (for example, a p-type or n-type substrate) and one or more pins 38 protruding from the body 36. The pin 38 is made entirely of an electrically conductive material and carries a high-voltage current. It is therefore desirable to electrically insulate the pin 38 from the cover 28 to prevent short circuits.

[0015] The cover 28 forms an inner cover surface 40 that partially delimits the cavity 32. The inner cover surface 40 faces the MOSFET 34 or another electronic component. The cover 28 defines a recess 42 that is at least partially defined by the inner cover surface 40. The SMCD 24 includes an electrical insulator 44 that is coupled to the inner cover surface 40 to prevent electricity from flowing from the pin 38 of the MOSFET 34 (or other electronic component) to the cover 28. The electrical insulator 44 may be located entirely within the recess 42.

[0016] The electrical insulator 44 forms an inner insulating surface 46 facing the MOSFET 34 or another electronic component. The inner insulating surface 46 is flush with the inner cover surface 40. The pin 38 is spaced from the electrical insulator 44 to form an air gap 48. The pin 38 is spaced from the electrical insulator 44 along a vertical direction V. Accordingly, the electrical insulator 44 is positioned over the pin 38 of the MOSFET 34. The electrical insulator 44 is made partially or entirely of an electrically insulating material, such as a polymer, ceramic, and / or glass enamel, to electrically insulate the cover 28 from the pin 38 of the MOSFET 34 or other electronic component.As non-restrictive examples, the electrical insulator 44 can consist wholly or partially of an elastomer and / or polytetrafluoroethylene (PTFE) to electrically insulate the cover 28 from the pin 38 of the MOSFET 34.

[0017] As mentioned previously, the pin 38 of the MOSFET 34 (or other electronic component) is spaced from the electrical insulator 44 to define the air gap 48. The air gap 48 has a gap length 50, which is defined from the pin 38 of the MOSFET 34 (or other electronic component) to the inner insulator surface 46 of the electrical insulator 44. The gap length 50 is greater than 3.0 millimeters (for example, 3.1 millimeters) to prevent electricity from flowing from the pin 38 of the MOSFET 34 (or other electronic component) to the cover 28, thus preventing short circuits. The electrical insulator 44 has an insulator thickness 52. The insulator thickness 52 is between 0.2 millimeters and 1 millimeter (for example, 0.3 millimeters) to prevent electricity from flowing from the pin 38 of the MOSFET 34 (or another electronic component) to the cover 28, thus preventing short circuits.The electrical insulator 44 has a dielectric strength. The dielectric strength of the electrical insulator 44 is between 9 kV / mm and 280 kV / mm (for example, 9 kV / mm) to prevent electricity from flowing from pin 38 of the MOSFET 34 (or another electronic component) to the cover 28, thus preventing short circuits.

[0018] The inner covering surface 40 has an inclined surface section 54 and a horizontal surface section 56. The horizontal surface section 56 is elongated along a horizontal direction H. The horizontal direction H is perpendicular to the vertical direction V. The inclined surface section 54 is angled obliquely relative to the horizontal surface section 56. The gap length 50 is defined from the pin 38 of the MOSFET 34 (or another electronic component) to the inner insulator surface 46 of the electrical insulator 44 along a longitudinal axis 58. The longitudinal axis 58 intersects the inclined surface section 54 at a perpendicular angle. The gap length 50 is parallel to the longitudinal axis 58. An angle θ is defined between the vertical direction V and the longitudinal axis 58. The angle θ is oblique (for example, 37 degrees).

[0019] The electrical insulator 44 electrically isolates the pin 38 of the MOSFET 34 (or another electronic component) with minimal modifications, without affecting the manufacturing process or costs. The electrical insulator 44 is made entirely or partially of an electrically insulating material with excellent dielectric strength in the short-circuit-prone areas of the SMCD 24. The manufacturing of the SMCD 24 involves selectively machining the cover 28 (for example, rectangular sections of varying lengths and widths, oriented according to the position required for electrical insulation). Furthermore, the manufacturing of the SMCD 24 includes filling and / or coating the machined areas with a high-quality electrical insulator 44.The manufacturing process of the SMCD 24 also achieves an excellent bond (e.g., curing) between the insulator 44 and the cover 28, which is maintained throughout the entire service life of the SMCD 24, which is exposed to harsh environmental, thermal, and mechanical conditions. As mentioned earlier, the electrical insulating materials can be ceramics, polymers, elastomers, and enamels. For example, PTFE can be used for the electrical insulator 44 due to its outstanding properties (i.e., excellent electrical insulation, durability, stability at extreme temperatures, chemical inertness, strong bond with aluminum), cost, availability, and ease of processing.

[0020] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the description are descriptive rather than limiting, and it is understood that various modifications may be made without departing from the spirit and scope of the description. As previously described, the features of different embodiments can be combined to form further embodiments of the presently disclosed system and method, which may not be expressly described or illustrated.While various embodiments might be described as advantageous or preferred over other embodiments or implementations of the prior art with respect to one or more desired properties, those skilled in the art recognize that one or more properties or features may be compromised to achieve desired overall system characteristics, which depend on the specific application and implementation. These properties may include, but are not limited to, cost, strength, durability, life-cycle costs, marketability, appearance, packaging, size, ease of maintenance, weight, manufacturability, ease of assembly, and so on. Embodiments described as less desirable than other embodiments or implementations of the prior art with respect to one or more features are therefore not outside the scope of the description and may be desirable for certain applications.

[0021] The drawings are simplified and not to scale. For the sake of simplicity and clarity only, directional terms such as above, below, left, right, over, above, under, behind, and in front may be used in the drawings. These and similar directional terms are not to be interpreted as limiting the scope of the description in any way.

[0022] Embodiments of the present description are described herein. It is understood, however, that the disclosed embodiments are merely examples and that other embodiments may take different and alternative forms. The illustrations are not necessarily to scale; some features may be exaggerated or reduced in size to show details of certain components. Therefore, specific structural and functional details disclosed herein are not to be understood as limiting, but merely as a representative basis to show the person skilled in the art how the system and method disclosed herein may be used in various ways.As experts know, various features illustrated and described with reference to one of the figures can be combined with features illustrated in one or more other figures to create embodiments not explicitly shown or described. The illustrated feature combinations represent embodiments for typical applications. However, various combinations and modifications of the features, consistent with the teachings of this description, may be desirable for specific applications or implementations.

[0023] This description serves only for illustration and is not intended to limit the disclosure, its application, or use in any way. The comprehensive teachings of the description can be implemented in a multitude of forms. Although this description contains particular examples, the true scope of the disclosure should not be so limited, as other modifications will become apparent upon studying the drawings, the description, and the following claims.

Claims

[1] Fuel cell system, comprising: a case; a fuel cell inside the casing; a device for monitoring and controlling the stack, which is mounted on the housing, the device for monitoring and controlling the stack comprising: an enclosure; a cover coupled to the enclosure to define a cavity, wherein the cover defines an inner cover surface and the inner cover surface partially defines the cavity; an electronic component located in the cavity between the housing and the cover, wherein the inner surface of the cover faces the electronic component and encompasses the electronic component: a body; and a pen that protrudes from the body; and an electrical insulator coupled to the inner cover surface, wherein the electrical insulator defines an inner insulator surface facing the electronic component, and the pin is spaced from the electrical insulator to define an air gap. [2] Fuel cell system according to claim 1, wherein the electronic component is a metal oxide semiconductor field-effect transistor, MOSFET, and the electrical insulator is arranged over the pin of the MOSFET. [3] Fuel cell system according to claim 1, wherein the electrical insulator is made entirely of polytetrafluoroethylene, PTFE. [4] Fuel cell system according to claim 1, wherein both the cover and the housing are made entirely of a metallic material and the cover defines a recess which is at least partially defined by the inner cover surface and the electrical insulator is arranged completely in the recess. [5] Fuel cell system according to claim 1, wherein the inner insulator surface is flush with the inner cover surface. [6] Fuel cell system according to claim 1, wherein the air gap has a gap length defined from the pin to the inner insulator surface, and the gap length is greater than 3.0 millimeters. [7] Fuel cell system according to claim 6, wherein the electrical insulator has an insulator thickness and the insulator thickness is between 0.2 millimeters and 1 millimeter. [8] Fuel cell system according to claim 7, wherein the electrical insulator has a dielectric strength and the dielectric strength is between 9 kV / mm and 280 kV / mm. [9] Fuel cell system according to claim 8, wherein the electrical insulator is made entirely of a ceramic. [10] Fuel cell system according to claim 8, wherein the electrical insulator is made entirely of a polymeric material.

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