Pulse inverter with cooling device and motor vehicle with pulse inverter

Abstract

The invention relates to a pulse inverter (3) for operating an electric machine of a motor vehicle, wherein the pulse inverter comprises a power module (4) for converting a direct current provided by a battery (1) of the motor vehicle into an alternating current, wherein the pulse inverter (3) comprises a cooling device for cooling components of the pulse inverter (3) by means of an electrically insulating cooling fluid flowing through the cooling device, wherein the cooling device comprises a fluid-tight housing, wherein the cooling fluid flowing through the fluid-tight housing is in direct contact with at least one of the components to be cooled, wherein the cooling device comprises a cooling channel (10), wherein the power module (4) is thermally connected to an outer surface of the cooling channel (10), wherein the cooling channel (10) comprises an outlet (11), wherein the outlet (11) opens into the fluid-tight housing, such that the cooling fluid flowing through the cooling device first flows through the cooling channel (10) and subsequently through the fluid-tight housing.

Description

Technical Field

[0001] This invention relates to a pulse inverter with a cooling device and a motor vehicle equipped with the pulse inverter. The pulse inverter is used to convert direct current (DC) into alternating current (AC) so that the motor can operate with AC current. Therefore, in electrically or partially electrically operated motor vehicles, the DC current supplied from the vehicle battery (typically a high-voltage battery) is converted into AC current by the intermediately connected pulse inverter. The current can also be converted in reverse, i.e., AC current is converted into DC current, for example, when the motor is operating in generator mode. Background Technology

[0002] Pulse inverters typically have multiple phase systems, each including at least one power module with semiconductor devices. The outer conductor of the corresponding phase system can be periodically switched using semiconductor devices, such as semiconductor switches, to convert direct current into alternating current, thereby applying an alternating current to the outer conductor. For example, the semiconductor devices can be FETs (field-effect transistors) or IGBTs (insulated-gate bipolar transistors). However, JFETs (junction-gate field-effect transistors) or MOSFETs (metal-oxide-semiconductor field-effect transistors) are also conceivable.

[0003] The semiconductor devices in a power module have ohmic resistance, which causes waste heat and thus an increase in temperature when current flows. Cooling devices are typically provided to protect the power module from overheating. Other components of a pulse inverter, such as intermediate circuit capacitors or contact rails, also have ohmic resistance, causing these components to heat up during pulse inverter operation.

[0004] For example, it is known from DE 10 2016 218 451 A1 that a power module is mounted on a heat sink, wherein the heat sink is constructed as an extruded profile. Summary of the Invention

[0005] The problem solved by this invention is to provide a pulse inverter having an improved cooling device that ensures particularly efficient cooling of the pulse inverter. Another problem of this invention is to provide a motor vehicle having such a pulse inverter.

[0006] These problems are addressed by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0007] The pulse inverter according to the invention is used to operate the motor of a motor vehicle, particularly for operating an electric motor. The pulse inverter includes at least one power module for converting direct current supplied by a motor vehicle battery into alternating current. The pulse inverter includes a cooling device for cooling components of the pulse inverter by means of an electrically insulating cooling fluid flowing through the cooling device. The cooling device includes a fluid-impermeable housing through which the electrically insulating cooling fluid flows, wherein the cooling fluid flowing through the fluid-impermeable housing is in direct contact with one of the components of the pulse inverter to be cooled. The cooling device also includes a cooling channel, wherein the power module is thermally connected to the outer surface of the cooling channel, wherein the cooling channel includes an outlet leading to the fluid-impermeable housing, such that the cooling fluid flowing through the cooling device first flows through the cooling channel and then through the fluid-impermeable housing.

[0008] The advantage of the aforementioned design of the cooling device is that the relatively cold cooling fluid first flows through the cooling channel, thereby cooling the power module particularly efficiently because the power module is in thermal contact with the cooling channel and thus uses the relatively cold cooling fluid flowing in the cooling channel to cool the power module. The power module is typically the component of the pulse inverter with the greatest cooling demand. On the other hand, the cooling demand of other components, such as contact rails and / or intermediate circuit capacitors, is generally less than that of the power module. The cooling fluid, heated only by the waste heat of the power module after flowing through the cooling channel, then flows into the impermeable housing, thus coming into direct contact with other components and / or the power module for cooling, while further heating it. According to the design of the invention, particularly efficient and sufficient cooling of the power module can be achieved because the relatively cold cooling fluid is specifically directed to the power module before flowing into the impermeable housing, and thus only then directly contacting other components of the pulse inverter to be cooled. If all components are cooled in the same way, for example through a pulse inverter housing that is impermeable to the inrush flow, i.e., without specifically directing the relatively cold cooling fluid to the power modules, especially the individual power modules, adequate cooling of the respective power modules may not be guaranteed, or the cooling fluid may have to be at a lower temperature for adequate cooling, or the volumetric flow rate may have to be increased, thereby increasing the power demand of the cooling system.

[0009] A particularly advantageous feature is that the pulse inverter includes multiple power modules, which are thermally connected to the outer surface of the same cooling channel. In this respect, the same cooling channel is used to cool multiple power modules.

[0010] What is considered particularly advantageous is that the power module is in direct contact with the cooling fluid flowing within an impermeable housing. In this respect, in the direction of the cooling fluid flow, the power module is first indirectly cooled via cooling channels, and then directly cooled via direct contact with the cooling fluid.

[0011] A particularly advantageous feature is that the power module itself has a fluid-impermeable power module housing, within which the semiconductor devices, or individual semiconductor devices, are arranged. This fluid-impermeable power module housing ensures that the semiconductor devices do not come into direct contact with the cooling fluid, thereby preventing damage to the power electronic devices or semiconductor devices due to conductive contaminants in the cooling fluid.

[0012] Preferably, the power module is arranged inside the fluid-impermeable housing of the pulse inverter.

[0013] Preferably, the impermeable housing forms the pulse inverter housing, which surrounds all components of the pulse inverter.

[0014] It is considered particularly advantageous when the cooling channels are arranged such that the cooling fluid flowing through the impermeable housing contacts one or all of the outer surfaces of the cooling channels. It is also considered particularly advantageous when the cooling channels are arranged within the impermeable housing such that the cooling fluid flowing through the housing surrounds the cooling channels. In this respect, the cooling channels are surrounded by cooling fluid on both their outer and inner sides. Preferably, the cooling fluid flowing within the impermeable housing flows around the cooling channels in a direction opposite to that of the cooling fluid in the cooling channels. This reverse flow direction allows for cooling that is as uniform as possible.

[0015] The electrically insulating cooling fluid is specifically a dielectric cooling fluid, preferably a cooling oil.

[0016] In a preferred embodiment, a plurality of power modules, a plurality of intermediate circuit capacitors, and a plurality of current-carrying contact rails connected to the power modules are arranged in a fluid-impermeable housing, wherein the cooling fluid flowing through the housing is in direct contact with the plurality of power modules, the plurality of intermediate circuit capacitors, and the plurality of current-carrying contact rails.

[0017] The cooling channel is preferably constructed as an extruded profile. It is conceivable that the cooling structure has been incorporated, for example, contracted or pressed into the cooling channel to provide directional delivery or guidance of the cooling fluid within the channel.

[0018] In a preferred embodiment, the corresponding power module is connected to the outer surface of the cooling channel in a material-fitting manner, such as by welding or bonding. This is considered particularly advantageous when the power module includes an external cooling plate, for example, made of copper, which contacts the outer surface of the cooling channel. Therefore, particularly efficient indirect cooling can be achieved. It is also considered particularly advantageous in this respect that the power module housing fluid-tightly surrounds the internal space of the power module, where the cooling plate is exposed and in contact with the cooling channel.

[0019] This is considered particularly advantageous when a cooling channel is designed between the power module and the intermediate circuit capacitors.

[0020] In a preferred embodiment, the cooling device includes another cooling channel, wherein the intermediate circuit capacitor is thermally connected to the outer surface of the other cooling channel, wherein the other cooling channel includes an outlet, wherein the outlet of the other cooling channel leads to the first cooling channel, such that cooling fluid flowing through the cooling device first flows through the other cooling channel, then through the first cooling channel, and subsequently through a fluid-impermeable housing.

[0021] In a preferred embodiment, the pulse inverter is defined as including a first row of power modules and a cooling channel associated with the first row of power modules, wherein the first row of power modules is thermally connected to the outer surface of the associated cooling channel, and wherein the pulse inverter includes a second row of power modules and a cooling channel associated with the second row of power modules, wherein the second row of power modules is thermally connected to the outer surface of the associated cooling channel, wherein the outlets of the two cooling channels open into the fluid-impermeable housing, such that cooling fluid flowing through the cooling device first flows through the respective cooling channel and then flows through the housing.

[0022] The motor vehicle according to the invention includes a motor vehicle battery, a motor, and a pulse inverter for operating the motor. The pulse inverter includes a power module for converting direct current supplied by the motor vehicle battery into alternating current. The pulse inverter includes a cooling device for cooling components of the pulse inverter by means of an electrically insulating cooling fluid flowing through the cooling device. The cooling device includes a fluid-impermeable housing, wherein the cooling fluid flowing through the fluid-impermeable housing is in direct contact with one of the components to be cooled. The cooling device also includes a cooling channel, wherein the power module is thermally connected to the outer surface of the cooling channel, wherein the cooling channel includes an outlet, wherein the outlet leads to the fluid-impermeable housing, such that the cooling device first flows through the cooling channel and subsequently through the fluid-impermeable housing.

[0023] It is considered particularly advantageous that the motor vehicle includes an electric motor cooling system for cooling the electric motor, wherein cooling fluid flowing out of an impermeable casing flows into the electric motor cooling system.

[0024] In this context, it is considered particularly advantageous when the cooling fluid flowing from the cooling device to the motor cooling system directly contacts and thereby cools the contact rail that electrically connects the pulse inverter to the motor.

[0025] The advantageous implementation schemes described in conjunction with pulse inverters are applicable to motor vehicles accordingly, and vice versa. Attached Figure Description

[0026] The invention is explained in more detail with reference to exemplary embodiments in the following figures, but is not limited thereto. The figures show:

[0027] Figure 1 The powertrain system of an electrically driven or partially electrically driven vehicle is illustrated in the diagram.

[0028] Figure 2 A schematic diagram showing the internal view of the pulse inverter is provided.

[0029] Figure 3 An internal view of the pulse inverter is shown in perspective.

[0030] Figure 4 It is based on Figure 3 An internal view of a pulse inverter, schematically showing the flow direction of the cooling fluid.

[0031] Figure 5 An embodiment of the cooling channel of the cooling device is shown in perspective view.

[0032] Figure 6 Shown in perspective according to Figure 5 The components of the cooling channel,

[0033] Figure 7 Another embodiment of the cooling channel is shown in perspective view.

[0034] Figure 8 A first embodiment of the cooling circuit is illustrated in the schematic diagram.

[0035] Figure 9 A second embodiment of the cooling circuit is illustrated in schematic diagram. Detailed Implementation

[0036] Figure 1The schematic diagram illustrates the components of a powertrain system for an electrically driven or partially electrically driven vehicle. The powertrain system includes an electric motor 1, a vehicle battery 2, and a pulse inverter 3, which converts the direct current supplied by the vehicle battery 2 into alternating current for operating the electric motor 1. The pulse inverter 3 includes multiple power modules 4, which comprise power electronic devices in the form of semiconductor devices. Furthermore, the powertrain system includes a control unit 5, which controls the pulse inverter 3 to convert the direct current voltage from the vehicle battery 2 into an alternating current voltage for driving the electric motor 1. During operation of the pulse inverter 3, very high currents flow through the semiconductor devices of the power modules 4. The resulting ohmic losses cause the power modules 4 to heat up. This heat must be dissipated. For this purpose, the power modules 4 are cooled by a cooling device 6, which is a component of a cooling circuit 16 in which cooling fluid flows. The direction of the cooling fluid flow is... Figure 1 The arrow in the text indicates this.

[0037] The cooling device 6 of the pulse inverter 3 is constructed in Figures 2 to 4 It is shown in more detail in the middle, where Figure 2 This is merely an illustrative diagram. The cooling device 6 includes a fluid-impermeable housing 7 through which the cooling fluid flowing through the housing 7 directly contacts the components to be cooled. In this case, the components of the pulse inverter 3 around which the cooling fluid flows directly are the power module 4, the intermediate circuit capacitor 8, and the contact rail 9. The cooling fluid is a dielectric cooling fluid, such as cooling oil. Therefore, the cooling fluid can directly contact the current-carrying components without the risk of short circuits or current flow via the cooling fluid. Thus, isolation of the current-carrying components that would adversely affect the cooling effect can be omitted.

[0038] The cooling device 6 includes a cooling channel 10, which is constructed as an extruded profile. The power module 4 is directly welded to the outer surface of the cooling channel 10. The outlet 11 of the cooling channel 10 leads to a fluid-impermeable housing 7, such that the cooling fluid flowing through the cooling device 6 first flows through the cooling channel 10 and then through the fluid-impermeable housing 7. In other words, the cooling oil flows out of the cooling channel 10 at the outlet 11 and into the entire interior of the pulse inverter 3, which is surrounded by the fluid-impermeable housing 7.

[0039] exist Figures 2 to 4In the embodiment of the pulse inverter 3 shown, a cooling channel 10 is arranged between the intermediate circuit capacitor 8 and the power module 4. Furthermore, the cooling device 6 includes another cooling channel 12 for indirect cooling of the intermediate circuit capacitor 8. For this purpose, the intermediate circuit capacitor 8 is thermally connected to the outer surface of the other cooling channel 12. The other cooling channel 12 includes an inlet 13 for cooling fluid and leads to the cooling channel 10 for cooling the power module 4. Therefore, the cooling fluid flowing through the cooling device 6 first flows through the other channel 12, then through the cooling channel 10, and subsequently through the impermeable housing 7.

[0040] As in Figure 3 and Figure 4 Specifically, the pulse inverter 3 includes a first row 19a power module 4 and a second row 19b power module 4. The corresponding rows 19a and 19b of the power modules 4 are associated with their respective cooling channels 10, and the associated intermediate circuit capacitors 8 are associated with another cooling channel 12. Both of the aforementioned devices are arranged in the same housing 7, which... Figure 3 and 4 This is not shown in more detail.

[0041] exist Figure 5 The image shows a cooling channel 10 in more detail, on which power modules 4 are arranged. Each power module 4 includes a closed, fluid-impermeable power module housing 14, which is directly surrounded by cooling fluid flowing within the housing 6. The power module housing 14 prevents the cooling fluid from directly contacting the semiconductor devices. The power modules 14 are soldered to the cooling channel 10 in a region at the bottom of each power module 4. For better heat conduction, each power module 4 includes a heat-conducting cooling plate made of copper at its bottom.

[0042] A corrugated cooling structure 15 is introduced into the cooling channel 10 to improve heat transfer from the power module 4 to the cooling fluid flowing in the cooling channel 10. For example... Figure 7 As illustrated, this cooling structure 15 can also be attached to the outer surface of the cooling channel 10.

[0043] Figure 8 An exemplary cooling circuit 16 in a motor vehicle including a pulse inverter 3 according to the invention is shown. In the cooling circuit 16, dielectric cooling oil circulates, and the cooling circuit 16 includes a heat exchanger 17 and a pump 18, wherein the pulse inverter 3 is arranged upstream of the motor 1 in the direction of flow of the cooling fluid. Therefore, the fluid flows first through the pulse inverter 3 and then through the motor 1. In this context, it is considered particularly advantageous that cooling fluid flowing from the housing 7 of the motor 1 or the motor cooling system of the motor 1 is delivered such that the contact rail 9, which electrically connects the pulse inverter 3 to the motor 1, directly contacts the cooling fluid and is thus cooled. Figure 9 Another embodiment of the cooling circuit 16 is shown, wherein this embodiment is consistent with that according to Figure 8 The fundamental difference in the implementation scheme is that, in order to cool the vehicle battery 2, cooling fluid also flows through the vehicle battery 2, wherein the vehicle battery 2 is arranged upstream of the pulse inverter 3 in the direction of cooling fluid flow. The cooling fluid flowing from the high-voltage battery 2 to the pulse inverter 3 directly contacts the contact rail 9 that electrically connects the high-voltage battery 2 and the pulse inverter 3, so as to directly cool it.

[0044] List of reference numerals

[0045] 1 motor

[0046] 2 Motor vehicle batteries

[0047] 3-pulse inverter

[0048] 4 power modules

[0049] 5 controllers

[0050] 6 Cooling devices

[0051] 7. Shell

[0052] 8 Intermediate Circuit Capacitors

[0053] 9 contact rails

[0054] 10 cooling channels

[0055] 11 Exports

[0056] 12 Another cooling channel

[0057] 13 entrances

[0058] 14 Power Module Housing

[0059] 15 Cooling Structure

[0060] 16 Cooling Circuits

[0061] 17 heat exchangers

[0062] 18 pumps

[0063] 19th row

Claims

1. A pulse inverter (3) for operating a motor (1) of a motor vehicle, wherein the pulse inverter (3) includes a power module (4) for converting direct current supplied by a motor vehicle battery (2) into alternating current, wherein the pulse inverter (3) includes a cooling device (6) for cooling components of the pulse inverter (3) by means of an electrically insulating cooling fluid flowing through the cooling device (6), the components including the power module (4), wherein the cooling device (6) includes a fluid-impermeable housing (7), wherein the cooling fluid flowing through the fluid-impermeable housing (7) interacts with at least one of the components to be cooled. Direct contact, wherein the cooling device (6) includes a cooling channel (10), wherein the power module (4) is thermally connected to the outer surface of the cooling channel (10), wherein the cooling channel (10) includes an outlet (11), wherein the outlet (11) leads to the impermeable housing (7), such that the cooling fluid flowing through the cooling device (6) first flows through the cooling channel (10) and then flows through the impermeable housing (7), thereby the relatively cold cooling fluid first flows through the cooling channel (10) and then the cooling fluid heated by the waste heat of the power module (4) flows through the impermeable housing (7), wherein, The cooling channel (10) is arranged within the impermeable housing (7) such that the cooling fluid flowing through the impermeable housing (7) flows around the cooling channel (10), wherein the power module (4) is in direct contact with the cooling fluid flowing in the impermeable housing (7), such that the power module (4) is first indirectly cooled via the cooling channel (10) in the direction of flow of the cooling fluid, and then directly cooled via direct contact with the cooling fluid.

2. The pulse inverter (3) according to claim 1, wherein the pulse inverter (3) includes a plurality of the power modules (4), wherein the plurality of power modules (4) are thermally connected to the outer surface of the cooling channel (10).

3. The pulse inverter according to claim 1 or 2, wherein a plurality of power modules (4), a plurality of intermediate circuit capacitors (8), and a plurality of contact rails (9) connected to the power modules (4) are arranged in the impermeable housing (7), wherein, The component includes a plurality of intermediate circuit capacitors (8) and a plurality of contact rails (9), wherein the cooling fluid flowing through the impermeable housing (7) is in direct contact with the plurality of power modules (4), the plurality of intermediate circuit capacitors (8) and the plurality of contact rails (9).

4. The pulse inverter according to claim 3, wherein the cooling device (6) includes another cooling channel (12), wherein the intermediate circuit capacitor (8) is thermally connected to the outer surface of the other cooling channel (12), wherein the other cooling channel (12) includes an outlet, wherein the outlet leads to the cooling channel (10), such that the cooling fluid flowing through the cooling device (6) first flows through the other cooling channel (12), then through the cooling channel (10), and then through the impermeable housing (7).

5. The pulse inverter according to claim 1 or 2, wherein the power module (4) includes a fluid-impermeable power module housing (14), wherein the semiconductor devices of the power module (4) are arranged within the power module housing (14).

6. A motor vehicle, comprising - Motor vehicle battery (2). - Motor (1), and - Pulse inverter (3) according to any one of claims 1 to 5.

7. The motor vehicle according to claim 6, wherein the motor vehicle includes a motor cooling system for cooling the motor (1), wherein the cooling fluid flowing out from the impermeable housing (7) flows into the motor cooling system.

8. The motor vehicle according to claim 7, wherein the cooling fluid flowing from the cooling device (6) to the motor cooling system directly contacts the contact rail (9) that electrically connects the pulse inverter to the motor, wherein, The component includes the contact rail and the contact rail is arranged in the fluid-impermeable housing (7).

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