FR3147463A1 - HEAT PIPE BASED COOLING MECHANISM FOR POWER MODULE OF ELECTRIC ENERGY CONVERTER - Google Patents

Abstract

HEAT PIPE BASED COOLING MECHANISM FOR POWER MODULE OF ELECTRICAL ENERGY CONVERTER The present subject matter relates to a heat pipe based cooling mechanism for a power module of an electrical power converter. An electrical power converter (100) according to the present subject matter comprises a housing (102), one or more power modules and at least one heat pipe (104). The at least one power module converts direct current into alternating current and/or vice versa. These modules are enclosed in the housing (102) and have a heat dissipating face (108). At least one heat pipe (104) is in thermal contact with the heat dissipating face (108) of the one or more power modules. The at least one heat pipe (104) comprises a first end (200) and a second end (202). The first end (200) is inside the housing (102) and in thermal contact with the heat sink face (108). The second end (202) extends outside the housing (102).

Description

HEAT PIPE BASED COOLING MECHANISM FOR POWER MODULE OF ELECTRIC ENERGY CONVERTER FIELD OF THE INVENTION

The present subject matter relates to a heat pipe-based cooling mechanism for a power module. More particularly, the present subject matter relates to a heat pipe-based cooling mechanism for a power module of an electric power converter.

CONTEXT

A generic type power module is known as a component of an electrical power converter for operating a rotating electrical machine. A power module in an electrical power converter facilitates the conversion of electrical power from alternating current (AC) to direct current (DC) and/or vice versa; and can be used in motor vehicle applications for operating rotating electrical machines, such as starters, alternators, motors, generators, motor-generators (or "reversible machines"). The electrical power converter here comprises one or more power modules, which are to be designed for short-term loading. The power module serves to carry and influence the current in one phase, i.e., depending on whether it is a single-phase or three-phase system, an appropriate number of electronic power modules is required. In automotive applications, the power module electrically interacts with an electrical network, such as the vehicle's on-board network. The on-board network is generally used to supply electrical energy to various devices, such as a rotating electrical machine, with which the motor vehicle is equipped. During operation, the power module(s) generate(s) heat and must therefore be cooled.

Typically, a power module in an electric power converter is cooled by circulating a coolant through cooling pipes/channels. The heat generated by the power module, during its operation, is absorbed by the coolant circulating in the cooling pipes and transferred to a bulk cooling channel of a system in which the power module is applied; and from the bulk cooling channel, the heat is dissipated to the environment by convection, for example, by the ambient air flow. In such a cooling system that circulates the coolant through cooling pipes, there are several interconnected cooling pipes and few cooling pipes that bend to navigate inside the housing in which the cooling pipes and the power module are housed. Such an arrangement of the cooling pipes is inefficient due to the risk of leakage. Thus, these systems are unreliable. Furthermore, the path taken by the heat to be transferred from its source to the ambient environment is long. When heat is not dissipated efficiently, the normal operation of the power module, and thus the system in which it is used, is disrupted due to overheating. The structural integrity of the power module is also susceptible to damage due to overheating. It is therefore desirable to have a more efficient cooling mechanism for transferring heat from the power module and a shorter path for transferring the heat and dissipating it to the ambient environment. Furthermore, given the limited size of the housing in which the power module(s) is/are housed, it is desirable that the means for cooling such module(s) be simple and structurally sound in terms of construction.

Therefore, the technical solution sought is to cool the power module(s) more efficiently while ensuring that the cooling of the power module(s) is carried out reliably in order to preserve the structural and operational integrity of said module.

The present subject matter aims to solve the above-mentioned technical problem. A generic type power module is known as a component of an electric power converter for operating a rotating electric machine. A power module in an electric power converter facilitates the conversion of electric power from alternating current (AC) to direct current (DC) and/or vice versa; and can be used in automotive applications for operating rotating electric machines, such as starters, alternators, motor generators (also known as "reversible machines" or "reversible rotating electric machines"), etc.

The present subject matter relates to an electrical power converter comprising a housing; one or more power modules for converting direct current (DC) into alternating current (AC) and/or vice versa, enclosed in the housing, and having a heat sink side; at least one heat pipe in thermal contact with the heat sink side, said heat pipe comprising a first end, inside the housing and in thermal contact with the heat sink side, and a second end extending outside the housing. The at least one heat pipe, configured in accordance with the present subject matter, is thus used in place of cooling pipes inside the housing. As a result, the number of parts required for cooling one or more power modules is reduced and the size of the housing is improved compared to existing housings/enclosures. Additionally, the assembly of an electrical power converter becomes simpler as there are fewer materials/parts involved. Heat dissipation is more efficient, while ensuring that the means of cooling the power module(s) is structurally and operationally reliable.

According to an example of the present subject matter, the heat sink side of one or more power modules comprises an integrated heat sink. Furthermore, by virtue of the above-mentioned thermal contact, heat generated by the power modules is transferred to the heat sink and from the heat sink to the heat pipe.

According to one aspect of the present subject matter, the at least one heat pipe comprises: an evaporator side adapted to absorb heat generated by one or more power modules, the evaporator side at the first end of the at least one heat pipe being in thermal contact with the heat sink side of one or more power modules; and a condenser side adapted to dissipate heat absorbed by the evaporator side, the condenser side at the second end of the at least one heat pipe being in thermal contact with a cooling pipe through which the cooling fluid flows. Accordingly, heat generated by one or more power modules is absorbed by the evaporator side at the first end and transferred to the condenser side at the second end; and from the second end, the heat is dissipated in a cooling pipe.

According to an example of the present subject matter, a portion of the second end is bent such that said heat pipe at least partially bypasses an outer periphery of the cooling pipe. This portion (or "bent portion"), being bent at the second end, exposes a larger surface area of the heat pipe to the second thermal contact with the cooling pipe. It is therefore possible to increase heat transfer.

According to one aspect of the present subject matter, an inner surface of the portion of the second end circumventing and in second thermal contact with the outer periphery of the cooling pipe is the condenser side. A larger surface area of the condenser side is exposed to the second thermal contact, thereby improving heat transfer.

According to an example of the present subject, the second thermal contact is a direct contact. Direct contact refers, in the present context, to a physical pressure contact between the condenser side at the second end and the cooling pipe.

According to another example of the present subject matter, a thermally conductive medium is applied between the second end and the cooling pipe to achieve the second thermal contact. This contact may be referred to as "indirect contact" to simplify the description of the present document.

In one example of the present subject matter, the thermal contact between the at least one heat pipe and the heat sink face of the at least one power module is a direct contact. Direct contact refers, in the present context, to a physical pressure contact between the at least one heat pipe (more specifically, the evaporator side at the first end) and the heat sink side.

According to another example of the present subject, a thermally conductive medium is applied between the first end and the heat sink side of the power module(s) to provide thermal contact.

According to one aspect of the present subject matter, a clamping device sandwiches and presses the second end of the heat pipe against the cooling pipe. The clamping device provides for the assembly of at least one heat pipe, configured in accordance with the present subject matter, and the cooling pipe. The clamping device comprises two parts between which said heat pipe (particularly at the second end) and the cooling pipe are assembled. Fasteners facilitate the aforementioned assembly or clamping.

The features, aspects and advantages of the present invention will be better understood in light of the following description and the accompanying figures. The description refers to the accompanying drawings, in which:

There illustrates an electrical power converter, in accordance with this subject;

There illustrates a perspective view of heat pipes and an overall cooling system, configured in accordance with this subject matter;

There illustrates a top view of the perspective described in , in accordance with this subject;

There illustrates an enlarged perspective of the heat pipe and overall cooling system, configured in accordance with this subject;

There illustrates a cross-sectional view of the heat pipes and overall cooling system from section AA of the , configured in accordance with this subject;

There illustrates a perspective view of the overall cooling system and heat pipe, the heat pipe being configured in accordance with another example of this subject matter;

There illustrates a cross-sectional view of the where the heat pipe at least partially bypasses the overall cooling system, configured in accordance with this subject; and

There illustrates another perspective of the global cooling system and heat pipes described in the , configured in accordance with this topic.

The figures are not necessarily to scale and the size of certain parts may be exaggerated to more clearly illustrate the example shown. In addition, the drawings provide examples and/or examples consistent with the description, but the description is not limited to the examples and/or examples provided in the drawings.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanying drawings, which are an integral part of the invention, and in which are illustrated specific embodiments in which the invention may be embodied. These embodiments are described in sufficient detail to enable one skilled in the art to practice the invention, and it is understood that the embodiments may be combined, or that other embodiments may be used, and that structural and logical modifications may be made without departing from the scope of the present invention. The detailed description which follows is therefore not to be construed in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents.

There illustrates an electrical power converter 100, in accordance with the present subject matter. The electrical power converter 100, in accordance with the present subject matter, comprises a housing 102, one or more power modules, and at least one heat pipe 104. The at least one power module is enclosed within the housing 102. These power modules have a heat dissipation face 108 from which the generated heat is prominent. The at least one power module is in thermal contact with at least one heat pipe 104. The at least one heat pipe 104 comprises two ends, namely a first end and a second end. Each of the power modules is in thermal contact with the first end of the at least one heat pipe 104. The second end extends outside the housing 102 of the electrical power converter 102.

In one aspect of the present subject matter, the at least one heat pipe 104 may be of a known type. The at least one heat pipe 104 includes an evaporator side 106a and a condenser side 106b. The evaporator side 106a is adapted to absorb heat generated by one or more power modules. A working fluid in the heat pipe transports the heat to the condenser side 106b, from where the heat is dissipated. In a non-limiting example, the working fluid in the heat pipe is water, ammonia, acetone, methanol, or any other working fluid capable of efficiently transferring heat.

In a non-limiting example, a cross-section of the at least one heat pipe 104 has a rectangular cross-section, the working fluid flowing in said heat pipe 104 is within the boundaries of said rectangular cross-section. In the aforementioned example, the evaporator side 106a and the condenser side 106b are on the long sides of the rectangular cross-section, the evaporator side 106a and the condenser side 106b being opposite each other in the rectangular cross-section.

According to one aspect of the present subject matter, the at least one heat pipe 104 is arranged such that said heat pipe 104 extends outside the housing 102. In this arrangement, the first end is inside the housing 102 and in thermal contact with one or more power modules; and the second end is outside the housing 102.

According to one aspect of the present subject matter, the evaporator side 106a at the first end of the heat pipe 104 is in thermal contact with the heat sink side 108 of one or more power modules. The working fluid in the at least one heat pipe 104 transports the aforementioned heat to the condenser side 106b at the second end of the heat pipe. Furthermore, from the condenser side 106b, heat is transferred to a cooling fluid circulating in the overall cooling system 110. This overall cooling system 110 comprises, for example, cooling pipes in which the cooling fluid circulates. In the example of the , only a portion of the overall cooling system 110 is shown to simplify the illustration. More specifically, a cooling pipe 112 is shown through which the cooling fluid circulates. In accordance with one aspect of the present subject matter, the at least one heat pipe 104 is secured to the cooling pipe 112 by a clamping device 114.

According to one aspect of the present subject matter, the second end of the heat pipe 104 is in second thermal contact with the overall cooling system 110, the overall cooling system 110 being available to absorb heat from the at least one heat pipe 104 and dissipate the heat to the surroundings or ambient air. The overall cooling system 110 described herein does not penetrate into the housing 102 of the electric power converter 100 and facilitates overall cooling of a system in which the electric power converter 100 is applied. For example, in an automotive application, the electric power converter 100 may be integrated with a rotating electric machine and, therefore, the overall cooling system 110 with its cooling pipes can cool the entire system, i.e., the electric power converter 100 and the rotating electric machine, while not penetrating into the housing 102 of the electric power converter 100.

There illustrates an exploded view of at least one heat pipe 104, the cooling pipe 112, and the clamping device 114, configured in accordance with the present subject matter. As explained in the preceding description, the at least one heat pipe 104 includes two ends. There are two heat pipes 104 shown in the examples of the figures, each of the two heat pipes 104 facilitating the transfer of heat from one or more power modules within the housing 102 of the power electronic converter 100 shown in the . The heat pipes 104 shown in the include, as explained in the description of the , a first end 200 and a second end 202. The first end 200 is disposed inside the housing 102. The second end 202 extends outside the housing 102. The first end 200 of each heat pipe 104 is in thermal contact with one or more power modules in the housing 102. More specifically, the heat pipes 104 are disposed such that the evaporator side 106a is in thermal contact with the heat sink side 108 of said power modules.

In one example of the present subject matter, the thermal contact between the one or more power modules and the first end 200 of the one or more heat pipes 104 is achieved by physical contact under pressure (or "direct contact"). By virtue of the aforementioned direct contact, the transfer of heat from the power modules to the heat pipe 104 is achieved by conduction. In another example of the present subject matter, a thermally conductive medium is applied between the first end 200 of at least one heat pipe 104 and one or more power modules. The thermally conductive medium may be a thermal glue that efficiently transfers heat by conduction. Accordingly, heat from one or more power modules is transferred to the at least one heat pipe 104 (particularly to the first end 200) via the thermal glue.

According to one aspect of the present subject matter, the second end of the at least one heat pipe 104 is a second thermal contact with the cooling pipe 112 of the overall cooling system 110. Therefore, during operation, heat from the condenser side 106b at the second end is transferred to the cooling pipe 112.

In one example of the present subject matter, the one or more power modules include an integrated heat sink. Each heat sink is part of the heat sink face 108 of the one or more power modules. Accordingly, the evaporator side 106a at the first end 200 of the at least one heat pipe 104 is in thermal contact with the heat sink of the one or more power modules. In the illustrated examples, there are two heat pipes 104, each in thermal contact with a heat sink. Each heat sink is associated with one or more power modules. Heat generated by the power modules is transferred to the heat sink, and from the heat sink to the heat pipe 104 via the thermal contact. The evaporator side 106a at the first end 200 of each heat pipe 104 is in thermal contact with a heat sink of the power module. The illustrated thermal contact is that of direct contact, but a thermally conductive medium may be applied between the two in one example. The heat transferred to the evaporator side 106a is transferred to the condenser side 106b at the second end 202, from where said heat is transferred to the cooling fluid circulating in the cooling pipe 112.

Therefore, in the illustrated figure, the first end 200, more precisely the evaporator side 106a, is in thermal contact with the heat sink integrated in the heat sink side 108 of one or more power modules. Accordingly, the heat generated by said power modules is transferred to at least one heat pipe 104 via the heat sink. In a non-limiting manner, a thermal glue is applied between the heat sink and said heat pipe 104 to improve the efficiency of the heat transfer.

In the illustrated examples, at least one heat pipe 104 is formed such that the two ends 200, 202 extend substantially perpendicular to each other. In other words, the at least one heat pipe 104 is formed in an L shape, with the first end 200 lying flat on the heat dissipation face 108 and the second end 202 being substantially perpendicular to the first end 200. The evaporator side 106 at the first end 200 faces the heat sink side 108 and is in thermal contact. The second end 202 extends to the cooling pipe 112 of the overall cooling system 110 and contacts said pipe 112. The condenser side 106b at the second end 202 is in second thermal contact with the cooling pipe 112. In the illustrated examples, there are two heat pipes 104, each formed in the aforementioned L-shaped manner.

There illustrates a top view of the heat pipes 104 and the cooling pipe 112 assembled by means of the clamping device 114, configured in accordance with the present subject matter. illustrates a sectional view at section AA indicated in the , configured in accordance with this topic. The illustrates a cross-sectional view of the components described in the and 3B, configured in accordance with this subject matter. For the sake of brevity and due to the similarity of reference numbers used, the description of the above-mentioned figures is provided herein in tandem.

According to an example of the present subject matter, the second thermal contact between the second end 202 and the cooling pipe 112 is a direct contact, i.e., there is a physical contact by pressure between the at least one heat pipe 104 and the cooling pipe 112. Accordingly, the heat carried by the heat pipe 104, which has been generated by one or more power modules, is transferred to the cooling pipe 112 (and thus to the overall cooling system 110) by virtue of the direct contact, i.e., by conduction. In yet another example, a thermally conductive medium, such as a thermal glue, is applied between at least one heat pipe 104 and the cooling pipe 112. Accordingly, heat transfer from said heat pipe 104 (in particular from the second end 202) is via the thermal glue to the overall cooling system 110. In the example where the second thermal contact is via the thermally conductive medium, this contact may be referred to herein as "indirect contact".

According to one aspect of the present subject matter, the clamping device 114 is formed of two parts 300, 302 fixed together by means of fasteners 204 (illustrated in ) in an assembled state. The two parts 300, 302 of the clamping device 114 sandwich at least one heat pipe 104 and the cooling pipe 112, thereby clamping said heat pipe 104 and said pipe 112 together. Furthermore, once the two parts are fixed together, or clamped together, the at least one heat pipe 104 and the cooling pipe 112 are assembled and the second thermal contact is made by means of direct contact or indirect contact.

As previously described, the examples illustrated in the figures represent at least one L-shaped heat pipe 104. The first end 200 of this heat pipe 104 is located inside the housing 102 and the second end 202 extends outside the housing 102. The first end 200 of this heat pipe 104 is located inside the housing 102 and the second end 202 extends outside the housing 102.

In the foregoing description, with reference to the examples shown in the , 2, 3A, 3B and 3C, only a portion 304 of at least one heat pipe 104, in particular at the second end 202, is in second thermal contact with the cooling pipe 112.

There illustrates the cooling pipe 112 and the at least one heat pipe 104, said heat pipe 104 being configured in accordance with another example of the present subject matter. illustrates a sectional view of the at least one heat pipe 104 and the cooling pipe 112, said heat pipe 104 being configured in accordance with the example of the . There illustrates an exploded view of at least one heat pipe 104, the cooling pipe 112 and the clamping device 114, said heat pipe 104 being configured in accordance with the examples of the and 4B. . For the sake of brevity and due to the similarity of reference numbers used, the description of the above-mentioned figures is provided herein in tandem.

According to an example of the present subject matter, the portion of the second end 202 that is in second thermal contact with the cooling pipe 112 is curved. This portion of the heat pipe 104 at least partially bypasses the cooling pipe 112. For reference, the curved portion at the second end 202, and in second thermal contact with the cooling pipe 112, is referred to herein as "curved portion 400". The bent portion 400 of the second end 202 is, for example, bent into a U shape such that the cooling pipe 112 is located inside the U-shaped bent portion 400 of the second end 202. As a result, a larger surface area of the heat pipe 104, and more specifically a larger surface area of the second end 202, is in second thermal contact with the cooling pipe 112. An inner surface of the bent portion 400 of the heat pipe is the condenser side 106b and is in second thermal contact with the cooling pipe 112. As explained above, the second thermal contact may be a direct or indirect contact, the indirect contact being achieved by means of a thermally conductive medium applied between the heat pipe 104 and the cooling pipe 112. In the example where the thermally conductive medium is applied, this medium is specifically applied between the condenser side 106b of the heat pipe 104 and the cooling pipe 112. and an outer periphery of the cooling pipe 112. Accordingly, heat transfer can take place between the condenser side 106b of the heat pipe 104 and the cooling pipe 112 in which the cooling fluid circulates.

In yet another example, an area of the condenser side 106b that is in second thermal contact with the cooling pipe 112 may be increased by further bending the curved portion 400 of the second end 202 to form a closed loop. As a result, the cooling pipe 112 passes through the closed loop formed by the heat pipe 104. In such a configuration (not shown), a greater area of the condenser side 106b (the condenser side 106b being the inner surface of the closed loop) is in second thermal contact with the cooling pipe 112. In other words, the second end 202 is substantially (or completely) bent to bypass the cooling pipe 112 and increase the area that is in second thermal contact with the cooling pipe 112.

According to one aspect of the present subject matter, the at least one heat pipe 104 (configured with the curved portion 400) and the cooling pipe 112 of the overall cooling system 110 are pressed together by the clamping device 114 and assembled by means of the fasteners 204. An exploded view of the aforementioned aspect is illustrated in FIG. .

Various modifications to the disclosed embodiments, as well as other embodiments of the subject matter, will become apparent to those skilled in the art upon reference to the description of the subject matter. It is therefore contemplated that such modifications will be made without departing from the scope of the present subject matter.

Claims (10)

Electric power converter (100) comprising:
a housing (102);
one or more power modules for converting direct current (DC) into alternating current (AC) and/or vice versa, enclosed in the housing (102), and having a heat dissipating face (108);
at least one heat pipe (104) in thermal contact with the heat dissipating face (108), said heat pipe (104) comprising a first end (200), inside the housing (102) and in thermal contact with the heat dissipating face (108), and a second end (202) extending outside the housing (102). The electrical power converter (100) of claim 1, wherein the heat sink side (108) of one or more power modules comprises an integrated heat sink. An electrical power converter (100) according to claim 1 or 2, wherein the at least one heat pipe (104) comprises:
an evaporator side (106a) adapted to absorb heat generated by one or more power modules, wherein the evaporator side (106a) at the first end (200) of the at least one heat pipe (104) is in thermal contact with the heat sink side (108) of the one or more power modules; and
a condenser side (106b) adapted to dissipate the heat absorbed by the evaporator side (106a), the condenser side (106b) at the second end (202) of the at least one heat pipe (104) being in a second thermal contact with a cooling pipe (112) in which the cooling fluid circulates An electrical power converter (100) according to claim 3, wherein a portion (304; 400) of the second end (202) is curved such that said heat pipe (104) at least partially bypasses an outer periphery of the cooling pipe (112). An electric power converter (100) according to claim 4, wherein an inner surface of the portion (304; 400) of the second end (202), bypassing and in second thermal contact with the outer periphery of the cooling pipe (112), is the condenser side (106b). Electrical power converter (100) according to one of claims 3 to 5, in which the second thermal contact is a direct contact. An electrical power converter (100) according to one of claims 3 to 5, wherein a thermally conductive medium is applied between the second end (202) and the cooling pipe (112) to provide the second thermal contact. Electrical power converter (100) according to one of claims 1 to 3, in which the thermal contact between at least one heat pipe (104) and the heat dissipating face (108) of one or more power modules is a direct contact. An electrical power converter (100) according to one of claims 1 to 3, wherein a thermally conductive medium is applied between the first end (200) and the dissipator side (108) of one or more power modules to provide thermal contact. An electric power converter (100) according to one of claims 1 to 9, wherein a clamping device (114) sandwiches and presses the second end (202) of the heat pipe (104) against the cooling pipe (112).