electric vehicle

Abstract

Electric vehicle, comprising an electric traction machine (12), a traction battery (14) for supplying the electric traction machine (12) with electrical energy, an inverter (20), wherein the electric traction battery (14) is electrically connected to the traction machine (12) via the inverter (20), and a cooling system (30) for cooling at least the traction battery (14) and the inverter (20), wherein the cooling system comprises a battery cooling circuit and (32) an inverter cooling circuit (34), wherein the battery cooling circuit (32) comprises a bypass line (36) which is thermally coupled to the inverter (20).

Description

[0001] The invention relates to an electric vehicle, comprising an electric traction machine, a traction battery for supplying the electric traction machine with electrical energy, an inverter, wherein the electric traction battery is electrically connected to the traction battery via the inverter, and a cooling system for cooling at least the traction battery and the inverter.

[0002] Such designs of electric vehicles are generally known from the prior art, with the term "electric vehicle" encompassing both purely electrically operated electric vehicles and hybrid vehicles, which have an internal combustion engine in addition to the electric traction motor. For example, DE 10 2020 118 521 A1 discloses such a design of an electric vehicle.

[0003] The hybrid vehicle disclosed in DE 10 2020 118 521 A1 comprises an electric traction motor for driving one or more vehicle wheels of the electric vehicle and a traction battery for supplying the electric traction motor with electrical energy. The electrical coupling between the traction battery and the electric traction motor is achieved via an inverter, in particular a pulse-controlled inverter, wherein the inverter converts a direct current stored in the traction battery into the alternating current required to operate the electric traction motor.

[0004] During operation of the electric vehicle, the electric traction motor, the traction battery, and the inverter heat up. Therefore, the electric vehicle has a cooling system to dissipate the heat generated during operation of the components and prevent component failure or a reduction in performance due to heating. A cooling system with multiple cooling circuits is provided to cool the electric traction motor, the traction battery, and the pulse-controlled inverter. DE 10 2020 128 728 A1 also discloses a similar design of an electric vehicle.

[0005] The disadvantage is that there is a risk that the cooling of the inverter might not be sufficient, and if the cooling is insufficient, the inverter might fail and the electric vehicle might no longer be able to operate.

[0006] The object of the invention is to provide reliable cooling of the inverter and thereby reliably prevent failure of the inverter due to overheating.

[0007] The problem is solved by the features of claim 1.

[0008] Because the cooling system comprises a battery cooling circuit and an inverter cooling circuit, with the battery cooling circuit having a bypass line thermally connected to the inverter, the inverter can be reliably cooled and inverter failure reliably prevented. Preferably, the battery cooling circuit and the inverter cooling circuit are completely separate from each other.

[0009] The inverter is cooled by the inverter cooling circuit independently of the cooling requirements of other components, thus covering the inverter's basic cooling requirements. If the inverter generates heat that exceeds the basic cooling requirements, the excess heat is dissipated through the bypass line of the battery cooling circuit, which is essentially thermally and fluidically separated from the inverter cooling circuit. In this way, the heat generated at the inverter during operation of the electric vehicle can be reliably dissipated, thus reliably preventing inverter failure.

[0010] Preferably, the bypass line has an inlet upstream of the traction battery in the direction of flow of the coolant flowing through the battery cooling circuit, and an outlet downstream of the traction battery in the direction of flow of the coolant flowing through the battery cooling circuit. Because the inlet of the bypass line is arranged upstream of the traction battery in the direction of flow, the coolant is not heated by the heat absorbed by the traction battery, so that the coolant flowing through the bypass line can absorb a relatively high amount of heat from the inverter. This achieves a high cooling effect on the inverter.

[0011] In a preferred embodiment, the bypass line has a bypass valve for controlling a coolant mass flow through the bypass line. This allows the basic cooling requirement to be covered by the inverter cooling circuit, and if the cooling requirement exceeds the basic cooling requirement, the battery cooling circuit can be activated via the bypass valve. It is crucial that the battery cooling circuit can be activated as needed to cool the inverter via the bypass valve, whereby the cooling of the traction battery must not be negatively affected, and if the cooling requirement of the traction battery is high at the same time, the cooling capacity for the inverter and the traction battery can be controlled via the bypass valve. The bypass valve can be a simple shut-off valve that can be adjusted between an open and a closed position.Otherwise, the bypass valve can be designed in such a way that a valve element can be adjusted to different intermediate positions in addition to the open and closed positions, and thus different coolant mass flows can be set.

[0012] In a preferred embodiment, the inverter has at least one semiconductor power module and at least one capacitor, wherein at least the capacitor is thermally connected to the bypass line. Due to the high expected heat buildup during operation, the semiconductor power module is typically thermally connected directly to the inverter cooling circuit. Compared to the semiconductor power module, the capacitor generates less waste heat during operation. Therefore, the focus is fundamentally on cooling the semiconductor power module. However, the capacitor is particularly temperature-sensitive, so there is a risk of the capacitor failing if it is not sufficiently cooled. The thermal coupling of the capacitor to the bypass line ensures that the capacitor is cooled, and capacitor failure can be reliably prevented.

[0013] Preferably, the cooling system has two cooling channels formed by the inverter, wherein a first cooling channel is fluidically connected to the inverter cooling circuit and thermally connected to the semiconductor power module and the second cooling channel is fluidically connected to the bypass line and thermally connected to the condenser.

[0014] In a preferred embodiment, the two cooling channels are thermally connected to one another, such that the two cooling channels together form a heat exchanger. As a result, in addition to the capacitor, the semiconductor power module is also cooled through the bypass line, with the heat absorbed by the coolant of the inverter cooling circuit being transferred to the coolant flowing through the bypass line and dissipated via the battery cooling circuit. The coolant preferably flows in opposite directions through the two cooling channels.

[0015] Alternatively, the second coolant channel is formed by an interior space of a housing of the inverter, such that the semiconductor power module and the capacitor are directly cooled by the coolant flowing through the second coolant channel. In this embodiment, the semiconductor power module is also cooled by the battery cooling circuit, with the coolant flowing through the interior flowing around the first cooling channel and / or the semiconductor power module as such.

[0016] Alternatively, the inverter has a central cooling channel, with the bypass line and the inverter cooling circuit being fluidly connected to the central cooling channel. The coolant from the bypass line is introduced into the central coolant channel through which the coolant from the inverter cooling circuit flows, with the condenser and the semiconductor power module being thermally connected to the central cooling channel. After flowing through the central cooling channel, the entire coolant introduced into the central cooling channel flows completely into the inverter cooling circuit.

[0017] This provides an electric vehicle in which reliable cooling of the inverter can be ensured, thus reliably preventing inverter failure due to overheating.

[0018] Several embodiments of the invention are explained in more detail with reference to the drawings. Fig. 1 shows schematically an electric vehicle, Fig. 2 shows schematically a basic structure of the cooling system, Fig. Figure 3a shows schematically a first embodiment of the cooling system according to Fig. 2, Fig. 3b shows schematically a second embodiment of the cooling system according to Fig. 2, Fig. 3c shows schematically a third embodiment of the cooling system according to Fig. 2, Fig. Figure 3d shows schematically a fourth embodiment of the cooling system according to Fig. 2.

[0019] Fig. 1 shows an electric vehicle 10, which includes, among other things, an electric traction machine 12, a traction battery 14, and an inverter 20. The traction battery 14 is electrically connected to the electric traction machine 12 via the inverter 20 and serves to supply the electric traction machine 12 with electrical energy. The inverter 20 converts a direct voltage stored in the traction battery 14 into the alternating voltage required to operate the electric traction machine 12. The inverter 20 has a semiconductor power module 24 and a capacitor 22, in particular an intermediate circuit capacitor. The semiconductor power module 24 and the capacitor 22 are shown in the Fig. 3a to 3d.

[0020] During operation of the electric vehicle 10, the electric traction motor 12, the traction battery 14, and the inverter 20 heat up and require cooling. For this purpose, the electric vehicle 10 has a cooling system 30. The cooling system 30 has a motor cooling circuit (not shown) that serves to cool the electric traction motor 12. The cooling system 30 also has a battery cooling circuit 32 for cooling the traction battery 14 and an inverter cooling circuit 34 for cooling the inverter 20.

[0021] The battery cooling circuit 32 is fluidically and thermally connected to the traction battery 14 via an inlet 38 and an outlet 40 and has a cooling device (not shown), wherein a coolant flowing through the traction battery 14 absorbs the waste heat from the battery cells of the traction battery 14 and releases it again via the cooling device, for example to the environment. For this purpose, the traction battery 14 can have a cooling plate (not shown), which is thermally coupled to the battery cells and through which the coolant of the battery cooling circuit 32 flows. Alternatively, the coolant of the battery cooling circuit 32 can flow completely or almost completely through the traction battery 14, wherein the coolant flows around the battery cells and is thereby directly cooled. In this case, a dielectric coolant is preferably used as the coolant.

[0022] The inverter cooling circuit 34 also has a cooling device (not shown) for dissipating the waste heat released by the inverter 20 to the coolant of the inverter cooling circuit 34. As shown in Fig. As shown in Figure 2, the inverter cooling circuit 34 is thermally and fluidically coupled to the inverter 20.

[0023] According to the invention, the battery cooling circuit 32 has a bypass line 36, which is thermally connected to the inverter 20. As a result, the inverter 20 is cooled not only by the inverter circuit 34 but also by the battery cooling circuit 32, i.e., by the bypass line 36, thus preventing a failure of the inverter 20 due to insufficient cooling.

[0024] The bypass line 36 extends from an inlet 42, which is arranged upstream of the inlet 38 of the traction battery 14 in the flow direction of the coolant of the battery cooling circuit 32, to an outlet 44, which is arranged downstream of the outlet 40 of the traction battery 14 in the flow direction of the coolant of the battery cooling circuit 32. To control the coolant volume flow through the bypass line 36, a bypass valve 46 is provided, which can be designed as a shut-off valve that can be adjusted exclusively between an open and closed position or as a control valve, wherein a control valve can be adjusted between an open and closed position and between different intermediate positions. The battery cooling circuit 32 orThe bypass line 36 can be activated to cool the inverter 20 if the cooling requirement of the inverter 20 exceeds the basic cooling requirement of the inverter cooling circuit 34. Thus, the battery cooling circuit 32 can be activated as needed via the bypass valve 46, whereby the cooling of the traction battery 14 is not negatively affected, or if the cooling requirement of the traction battery 14 is simultaneously high, the cooling capacity for the inverter 20 and the traction battery 14 is controlled via the bypass valve 46.

[0025] The Fig. 3a, Fig. 3b, Fig. 3c and Fig. 3d shows different versions of the cooling system 30.

[0026] Fig. 3a shows an inverter 20 having two cooling channels 50, 52. The capacitor 22 is adjacent to the first cooling channel 50 such that the capacitor 22 is cooled by the coolant flowing through the first cooling channel 50. The first cooling channel 50 is fluidically connected to the bypass line 36 of the battery cooling circuit 32. The second cooling channel 52 is fluidically connected to the inverter cooling circuit 34, with the semiconductor power module 24 adjacent to the second cooling channel 52 such that the semiconductor power module 24 is thermally coupled to the second cooling channel 52. Thus, the semiconductor power module 24 is cooled exclusively by the inverter cooling circuit 34, and the capacitor 22 is cooled exclusively by the battery cooling circuit 32.

[0027] Fig. 3b shows a second embodiment of the cooling system 30. As in the first embodiment of Fig. 3a, the capacitor 22 is thermally connected to the first cooling channel 60 and the semiconductor power module 24 is thermally connected to the second cooling channel 62. The crucial difference from the first embodiment of Fig. 3a is that the two cooling channels 60, 62 abut one another and are thermally connected. As a result, the two cooling channels 60, 62 form a heat exchanger 64, which also allows heat to be transferred between the battery cooling circuit 32 and the inverter cooling circuit 34. In this way, in addition to the capacitor 22, the semiconductor power module 24 is also cooled by the battery cooling circuit 32.

[0028] Fig. 3c shows a third embodiment of the cooling system 30, slightly modified from the second embodiment, wherein the second cooling channel 72 is formed by the interior space 25 of the inverter 20. In this way, all components, in particular the capacitor 22 and the semiconductor power module 24, are cooled by the battery cooling circuit 36. The first cooling channel 70, on which the semiconductor power module 24 is arranged and is thereby cooled, is also surrounded by coolant flowing through the second cooling channel 72, thus resulting in heat transfer between the two coolants flowing through the cooling channels 70, 72. As a result, the two cooling channels 70, 72 also form a heat exchanger 74.

[0029] Fig. 3d again shows a modified, fourth embodiment of the cooling system 30, wherein only a single central cooling channel 80 is provided, to which the capacitor 22 and the semiconductor power module 24 are thermally coupled. The central cooling channel 80 is fluidically connected on the inlet side to both the inverter cooling circuit 34 and the battery cooling circuit 32 or to the bypass line 36. The outlet of the central cooling channel 80 is fluidically connected exclusively to the inverter cooling channel 34. By means of such an embodiment, as in the two embodiments according to Fig. 3b and Fig. 3c, the semiconductor power module 24 and the capacitor 22 are cooled by the battery cooling circuit 32 and the inverter circuit 34 by thermally coupling the two cooling circuits 32, 34 within the inverter 20. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2020 118 521 A1 [0002, 0003] DE 10 2020 128 728 A1

[0004]

Claims

[1] Electric vehicle, with an electric traction machine (12), a traction battery (14) for supplying the electric traction machine (12) with electrical energy, an inverter (20), wherein the electric traction battery (14) is electrically connected to the traction machine (12) via the inverter (20), and a cooling system (30) for cooling at least the traction battery (14) and the inverter (20), wherein the cooling system has a battery cooling circuit (32) and an inverter cooling circuit (34), characterized by , that the battery cooling circuit (32) has a bypass line (36) which is thermally coupled to the inverter (20). [2] Electric vehicle according to claim 1, characterized bythat the bypass line (36) has an inlet (38) upstream of the traction battery (14) in the flow direction of a coolant flowing through the battery cooling circuit (32) and an outlet (40) downstream of the traction battery (14) in the flow direction of the coolant flowing through the battery cooling circuit (32). [3] Electric vehicle according to claim 1 or 2, characterized by that the bypass line (36) has a bypass valve (46) for controlling a coolant mass flow through the bypass line (36). [4] Electric vehicle according to one of the preceding claims, characterized by that the inverter (20) has a semiconductor power module (24) and at least one capacitor (22), wherein at least the capacitor (22) is thermally coupled to the bypass line (36). [5] Electric vehicle according to claim 4, characterized byin that the cooling system (30) has two cooling channels (50, 52, 60, 62, 70, 72) formed by the inverter (29), wherein a first cooling channel (52, 62, 70) is fluidically connected to the inverter cooling circuit (34) and thermally connected to the semiconductor power module (24) and the second cooling channel (50, 60, 72) is fluidically connected to the bypass line (36) and thermally connected to the condenser (22). [6] Electric vehicle according to claim 5, characterized by that the two cooling channels (60, 62; 70, 72) are thermally connected to one another in such a way that the two cooling channels (60, 62; 70, 72) together form a heat exchanger (64, 74). [7] Electric vehicle according to claim 6, characterized by that the coolant flows in opposite directions through the two cooling channels (60, 62; 70, 72). [8] Electric vehicle according to claim 6 or 7, characterized bythat the second cooling channel (72) is formed by an interior space (25) of a housing (21) of the inverter (20), such that the semiconductor power module (24) and the capacitor (22) are directly cooled by the coolant flowing through the second cooling channel (72). [9] Electric vehicle according to one of claims 1 to 4, characterized by that the cooling system (30) has a single cooling channel (80) formed by the inverter (29), wherein the bypass line (36) and the inverter cooling circuit (34) are fluidically connected to the central cooling channel (80).

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