DE102021208350A1 - AC busbar support for inverters for operating an electric drive of an electric vehicle or a hybrid vehicle, inverter - Google Patents

Abstract

The invention relates to an AC busbar support (10) for an inverter for operating an electric drive in an electric vehicle and/or a hybrid vehicle, the inverter comprising a plurality of semiconductor switching elements which are used to convert an input-side DC current into an output-side DC current by switching the semiconductor switching elements multi-phase AC current with multiple phase currents, wherein the AC busbar support (10) has a support body (14) formed from an electrically insulating material and a plurality of AC busbars (12A-C) which are used for conducting the respective phase currents in the support body (14 ) are arranged, wherein a current sensor (16), which is attached to a printed circuit board (22) of the inverter, for detecting the phase current flowing in one of the AC busbars (12A-C) is arranged on the carrier body (14) such that a Distance between a side face (162) of the current sensor (16) facing the AC busbar (12A-C) and the AC bus rail (12A-C) is a maximum of 1.5 millimeters, preferably a maximum of 0.5 millimeters, more preferably a maximum of 0.1 millimeters.

Description

The invention relates to an AC busbar support for inverters for operating an electric drive of an electric vehicle or a hybrid vehicle according to the preamble of claim 1 and a corresponding inverter.

Purely electric vehicles and hybrid vehicles are known in the prior art, which are driven exclusively or in support of one or more electric machines as drive units. In order to supply the electric machines of such electric vehicles or hybrid vehicles with electric energy, the electric vehicles and hybrid vehicles include electric energy stores, in particular rechargeable electric batteries. These batteries are designed as DC voltage sources, but the electrical machines usually require an AC voltage. Therefore, power electronics with a so-called inverter are usually connected between a battery and an electric machine of an electric vehicle or a hybrid vehicle.

Such inverters typically include semiconductor switching elements typically formed of transistors. It is known to provide the semiconductor switching elements in different degrees of integration, namely either as discrete individual switches with a low degree of integration but high scalability, as power modules with a high degree of integration but low scalability, and as half-bridges, which in terms of degree of integration and scalability between individual switches and half-bridges rank

Due to the internal electrical resistance of the power lines integrated in the inverter, heat is generated during operation of the inverter, which increases with increasing current strength. In order to protect the semiconductor switching elements and other current-carrying electronic components in the inverter from excessive current and the associated overheating, a current measurement is carried out for the individual current phases. In particular, this is intended to prevent a maximum operating current, which is a characteristic variable of the semiconductor switching elements, from being exceeded. In the inverters known from the prior art, current sensors are used for the purpose of detecting the AC phase currents generated by means of the semiconductor switching elements.

Nevertheless, in the case of the known inverters, a potential separation between the current sensors and other potential-bearing components in the inverter is not sufficiently guaranteed. Also, current sensing is limited in accuracy because current sensors are often not placed close enough to the AC power lines. In addition, the attachment of the current sensor in the inverter is often not sufficiently stable, so that vibrations from the area around the current sensor lead to an additional reduction in the measurement accuracy.

It is an object of the invention to provide an AC bus bar support in order to at least partially eliminate the disadvantages mentioned above.

According to the invention, this object is achieved by the AC busbar support and the inverter according to the independent patent claims. Advantageous refinements and developments of the invention emerge from the dependent patent claims.

The invention relates to an AC busbar support used for an inverter for operating an electric drive in an electric vehicle and/or a hybrid vehicle. The inverter includes a plurality of semiconductor switching elements which are designed to convert an input-side DC current into an output-side multi-phase AC current with a plurality of phase currents by switching the semiconductor switching elements. A plurality of DC power terminals (particularly positive and negative DC power terminals) are attached to the inverter for feeding the DC power generated by a battery on the input side. At the same time, a number of AC power connections are provided for delivering the AC power generated by means of the semiconductor switching elements. The AC busbar support connects the AC power connections and the electric drive, for example the electric motor to be powered. For this purpose, several AC busbars are arranged for conducting the respective phase currents, so that each AC busbar is permanently assigned to a specific AC power connection and a specific phase current. The AC busbars are integrated in a support body of the AC busbar support. The carrier body is formed from an electrically insulating material, such as plastic. The carrier body is preferably created by overmolding the AC busbars with a plastic-based injection molding material.

A printed circuit board is also provided in the inverter, which is equipped with electronic components for controlling the semiconductor switching elements. A current sensor for detecting the phase currents is integrated in the AC busbar support. Here, the current sensor is attached to the circuit board of the inverter on the one hand, and on the other hand to detect the phase current flowing in one of the AC busbars Roms arranged on the carrier body in such a way that a distance between a side surface of the current sensor facing the AC busbar and the AC busbar is a maximum of 1.5 millimeters, preferably a maximum of 0.5 millimeters, more preferably a maximum of 0.1 millimeters.

In this way, the current sensor can be securely fastened in the inverter, with the current sensor being reliably isolated from other components of the inverter that have potential. At the same time, the current sensor is mechanically stable. Due to the comparatively reduced distance between the current sensor and the AC busbar, a particularly accurate current detection is also favored.

According to one embodiment, a recess for accommodating the current sensor is formed on an upper side of the carrier body facing the printed circuit board. The AC busbar is preferably arranged below the cutout, so that the AC busbar at least partially vertically overlaps the cutout. This allows for a reduced distance between the current sensor and the AC busbar.

According to a further embodiment, a base part of the recess is arranged between the side surface of the current sensor and the AC busbar.

The bottom part is part of the carrier body formed from the electrically insulating material. This ensures reliable electrical isolation between the current sensor and the AC busbar.

According to a further embodiment, an insulating film is arranged on a top side of the carrier body facing the printed circuit board. The insulating film can be made particularly thin and ensures a reduced distance and at the same time reliable electrical isolation between the current sensor and the AC busbar.

According to a further embodiment, a through-opening for accommodating the current sensor is formed in the AC busbar. In this way, the current sensor can determine the amperage of the phase current present in the AC busbar by detecting the magnetic field strength at not just one but two locations around the AC busbar. This increases the accuracy of the current measurement.

According to a further embodiment, the carrier body has a jacket attachment which extends into the through-opening and encloses the current sensor accommodated there. The fact that the jacket attachment is also formed from the electrically insulating material as a component of the carrier body enables reliable potential isolation between the current sensor and the AC busbar.

According to a further embodiment, an intermediate space between the current sensor and an inner wall of the through-opening is completely filled by the jacket attachment. This measure increases the safety of the electrical isolation between the current sensor and the AC busbar.

According to a further embodiment, the casing attachment is attached to an inner wall of the through-opening in such a way that the current sensor is laterally spaced from the casing attachment. This allows the distance between the current sensor and the AC busbar to be further reduced.

According to a further embodiment, a thermally conductive insulating coating is attached to an underside of the carrier body that faces away from the printed circuit board. The insulating coating provides electrical isolation of the entire AC busbar from other potential components of the inverter. In addition, the AC busbar can be effectively cooled.

The invention further relates to the inverter described above with such an AC busbar support. This results in the advantages already described in connection with the AC busbar support according to the invention for the inverter according to the invention as well.

The invention is explained below by way of example using the embodiments shown in the figures.

• 1 beispielhaft und schematisch einen möglichen Aufbau eines erfindungsgemäßen AC-Stromschienenträger für einen elektrischen Antrieb eines Elektrofahrzeugs oder eines Hybridfahrzeugs in Perspektivansicht inklusive eines Teilausschnittes einer Leiterplatte;
• 2 den erfindungsgemäßen AC-Stromschienenträger aus 1 in einer weiteren Perspektivansicht;
• 3 den erfindungsgemäßen AC-Stromschienenträger aus 1 in einer seitlichen Schnittansicht;
• 4 eine schematische Darstellung des AC-Stromschienenträgers gemäß einer weiteren Ausführungsform;
• 5 eine schematische Darstellung des AC-Stromschienenträgers gemäß einer weiteren Ausführungsform;
• 6 eine schematische Darstellung des AC-Stromschienenträgers gemäß einer weiteren Ausführungsform;
• 7 eine schematische Darstellung eines Verfahrens zum Herstellen des AC-Stromschienenträgers aus 6;
• 8 eine schematische Darstellung des AC-Stromschienenträgers gemäß einer weiteren Ausführungsform;
• 9 eine schematische Darstellung eines Verfahrens zum Herstellen des AC-Stromschienenträgers aus 8.

Show it:

• 1 as an example and schematically a possible structure of an AC busbar support according to the invention for an electric drive of an electric vehicle or a hybrid vehicle in a perspective view including a partial section of a printed circuit board;
• 2 the AC busbar support according to the invention 1 in another perspective view;
• 3 the AC busbar support according to the invention 1 in a side sectional view;
• 4 a schematic representation of the AC busbar support according to a further embodiment;
• 5 a schematic representation of the AC busbar support according to a further embodiment;
• 6 a schematic representation of the AC busbar support according to a further embodiment;
• 7 a schematic representation of a method for manufacturing the AC busbar support 6 ;
• 8th a schematic representation of the AC busbar support according to a further embodiment;
• 9 a schematic representation of a method for manufacturing the AC busbar support 8th .

Identical objects, functional units and comparable components are denoted by the same reference symbols across the figures. These objects, functional units and comparable components are designed to be identical in terms of their technical features, unless the description explicitly or implicitly states otherwise.

1 FIG. 1 shows, schematically and by way of example, an AC busbar support 10 which is installed in an inverter (not fully shown here). The inverter generally includes a plurality of semiconductor switching elements which are designed to convert an input-side DC current into an output-side multi-phase AC current with a plurality of phase currents by switching the semiconductor switching elements. A plurality of DC power terminals (particularly positive and negative DC power terminals) are attached to the inverter for feeding the DC power generated by a battery on the input side. At the same time, a number of AC power connections are provided for delivering the AC power generated by means of the semiconductor switching elements.

The AC busbar support 10 connects the AC power connections and the electric drive, for example the electric motor to be powered. For this purpose, several AC busbars 12A-C are arranged to conduct the respective phase currents, so that each AC busbar 12A-C is permanently assigned to a specific AC power connection and a specific phase current. As in 1 As shown schematically, a printed circuit board 22 of the inverter is attached to the top of the AC bus bar support 10 by means of screws, although other methods of connection, such as heat-swaged plastic domes, can be used instead of screws. The circuit board 22 is equipped with electronic components for controlling the semiconductor switching elements.

As in the perspective view in 2 As shown schematically, the AC bus bars 12A-C are integrated into a support body 14 of the AC bus bar support. The carrier body 14 is formed from an electrically insulating material, such as plastic. In the embodiment shown here as an example, the carrier body 14 is created by overmolding the AC busbars 12A-C with a plastic-based injection molding material. The support body 14 has a beam 15 to which the AC busbars 12A-C are attached on the power connection side. The AC busbars 12A-C comprise a plurality of output contacts which protrude laterally from the bar 15 in order to feed the AC phase currents into the electric motor - Busbar 12A-C are assigned. Attached to each wing 19A-C are a plurality of input contacts 24A-C which project laterally from the respective wing 19A-C in an opposite direction from the output contacts. A plurality of input contacts 24A-C are assigned to each output contact or AC bus bar 12A-C in order to be contacted by the half-bridges.

A recess 17 for placing a current sensor 16 is provided on one surface of each vane 19A-C. The current sensor 16 serves to detect the phase currents flowing in the AC bus bars 12A-C. The current sensor 16 is shown in a side sectional view in FIG 3 shown closer. As can be seen there, the current sensor 16 is fastened on the one hand to the circuit board 22 and on the other hand is arranged on the carrier body 14 in such a way that a distance between a side surface 162 facing the AC busbar 12A-C (see 4 , 5 , 6 , 8th ) of the current sensor 16 and the AC busbar 12A-C is a maximum of 1.5 millimeters, preferably a maximum of 0.5 millimeters, more preferably a maximum of 0.1 millimeters.

As in 3 The printed circuit board 22 is also fastened to the carrier body 14 by means of a screw 26 . At the same time, the AC bus bar 12A-C is attached to a housing of the inverter. However, the screws 26 only represent one of several possible fastening methods. Alternatively, heat-calked plastic domes can be used. The carrier body 14 was created here, for example, by overmolding the AC busbars 12A-C. The current sensor 16 is fitted, for example, as an SMD component on a rear side 222 of the printed circuit board 22 facing the carrier body 14, which at the same time acts as a signal line acts. As in 6-9 shown, the current sensor 16 can be contacted with the printed circuit board 22 by THT soldering or press-fit pins. An insulating coating 20 is applied to an underside 150 of the AC busbar 12A-C that faces away from the printed circuit board 22 in order to electrically insulate the AC busbar 12A-C from other non-potential components of the inverter. At the same time, the insulating coating 20, which is formed from a thermally conductive material, serves for thermal coupling between the AC bus bar 12A-C and a heat sink (not shown) installed in the inverter.

4 and 5 each show an AC busbar support 10A,B according to an embodiment. In the 4-5 The embodiments shown are the one shown in FIG 1-3 shown general embodiment similar in principle. For example, the current sensor 16 is also off there, as in the general embodiment 1-3 shown, the back of the circuit board 22 fixed. Also, in the embodiments, is off 4-5 a thermally conductive insulation coating 20 is also attached underneath the AC busbar 12A-C.

The two embodiments in 4-5 differ, however, in the shape of the carrier body 14. In the in 4 The embodiment shown is as in the sectional view in FIG 4B As can be seen, the current sensor 16 is accommodated in a recess 144 of the carrier body 14 . The recess 144 is formed on an upper side 142 of the carrier body 14 and includes a base part 146, which the side surface 162 of the current sensor 16 faces. A gap may be formed between side surface 162 and bottom portion 146 . The base part 146, which is part of the carrier body 14 and is therefore formed from the current-insulating material (such as plastic injection molding material), ensures electrical insulation or potential separation between the current sensor 16 and the AC busbar 12A-C. Due to the small layer thickness of the base part 146, it is also possible to maintain the maximum distance of 1.5 millimeters, preferably 0.5 millimeters, more preferably 0.1 millimeters.

At the in 5 In the embodiment shown, on the other hand, an insulating film 18 is applied to the upper side 142 of the carrier body 14 for the purpose of electrical insulation. In this example, the current sensor 16 rests directly on the insulating film 18 after the printed circuit board 22 has been connected to the carrier body 14 . Alternatively, the current sensor 16 can be arranged in such a way that the current sensor 16 has the same distances to the AC busbar 12A-C and the carrier body 14 (see FIG 4 ). The insulating film 18 ensures potential isolation between the current sensor 16 and the AC busbar 12A-C. At the same time, the thickness of the insulating film 18 can be selected such that the maximum distance of 1.5 millimeters, preferably 0.5 millimeters, more preferably 0.1 millimeters is maintained.

6 until 9 show two further embodiments of the AC busbar support 10C,D according to the invention. In contrast to the 1-5 In the embodiments shown, the AC bus bar 12A-C has a through hole 122 extending from a top to a bottom of the AC bus bar 12A-C. The through-opening 122 is designed in such a way as to receive the current sensor 16 in a laterally enclosing manner. The through hole 122 can be provided in two ways.

6 shows an embodiment of the AC bus bar support 10C, in which the through opening 122 according to a in 7 method shown is provided. 6B Figure 12 shows a sectional view along a first section line PP 6A . 6C FIG. 14 is a sectional view taken along a second sectional line QQ 6A . To provide the through opening 122, the AC bus bar 12A-C is first overmolded with a plastic material to form the carrier body 14. Here, a central area, which is defined by an edge 28 (see 6B-C and 7 ) is included, covered during the injection molding process with a corresponding workpiece, so that no plastic material gets into the middle area and the carrier body 14 has a corresponding gap. Only in an intermediate area between an inner wall 124 of the recess 122 and the gap is a jacket attachment that ensures potential isolation between the current sensor 16 and the AC busbar 12A-C. After the injection molding process, the workpiece is removed from the central area and the current sensor 16 already fixed to the printed circuit board 22 is introduced into the central area.

8th shows an embodiment of the AC busbar support 10D, in which the through hole 122 according to a FIG 9 method shown is provided. 8B Figure 12 shows a sectional view along a first section line PP 8A . 8C FIG. 14 is a sectional view taken along a second sectional line QQ 8A . To provide the through hole 122, the current sensor 16, as in FIG 9 shown, without connection to the printed circuit board 22 placed centrally in the recess 122 of the AC busbar 12A-C. In this position of the current sensor, the AC current busbar 12A-C is overmoulded. Alternatively, the current sensor could be mounted in the encapsulation and then the printed circuit board is mounted and contacted with the current sensor. After the spray During the casting process, the circuit board 122 is plugged into the current sensor 16 on the top side.

In contrast to the embodiment 6 , where a gap between the side surface 162 of the current sensor 16 and the rim 28 is exposed by the molding material, the gap between the side surface 162 and the inner wall 124 of the AC bus bars 12A-C is completely filled with the molding material. In both variants, the maximum distance of 1.5 millimeters, preferably 0.5 millimeters, more preferably 0.1 millimeters can be effectively and easily maintained. A potential separation between the current sensor 16 and the AC busbar 12A-C is also ensured due to the current-isolating property of the carrier body (or the injection-molded material).

Reference List

10, 10A-D

AC busbar support

12A-C

AC busbars

122

passage opening

124

inner wall

14

carrier body

142

top

144

recess

146

bottom part

148

jacket attachment

150

bottom

16

current sensor

162

side face

164

connector

17

recess

18

insulation film

19A-C

wing

20

insulation coating

22

circuit board

24A-C

input contacts

Claims (11)

AC busbar support (10) for an inverter for operating an electric drive in an electric vehicle and/or a hybrid vehicle, the inverter comprising a plurality of semiconductor switching elements which are used to convert an input-side DC current into an output-side multi-phase AC current by switching the semiconductor switching elements with a plurality of phase currents, the AC busbar support (10) having a support body (14) formed from an electrically insulating material and a plurality of AC busbars (12A-C) which are arranged in the support body (14) for conducting the respective phase currents, wherein a current sensor (16), which is fixed to a circuit board (22) of the inverter, for detecting the phase current flowing in one of the AC bus bars (12A-C) is arranged on the support body (14) such that a distance between one of the AC busbar (12A-C) facing side surface (162) of the current sensor (16) and the AC busbar (12A-C) maximum 1. 5 millimeters, preferably a maximum of 0.5 millimeters, more preferably a maximum of 0.1 millimeters. AC busbar support (10) according to claim 1 , A recess (144) for receiving the current sensor (16) being formed on a top side (142) of the carrier body (14) facing the printed circuit board (22). AC busbar support (10) according to claim 2 , wherein a base part (146) of the recess (144) is arranged between the side surface (162) of the current sensor (16) and the AC busbar (12A-C). AC busbar support (10) according to one of Claims 1 until 3 , An insulating film (18) being arranged on a top side (142) of the carrier body (14) facing the printed circuit board (22). AC busbar support (10) according to claim 1 wherein a through hole (122) for receiving the current sensor (16) is formed in the AC bus bar (12A-C). AC busbar support (10) according to claim 5 , The carrier body (14) having a jacket attachment (148) which encloses the current sensor (16) accommodated in the through-opening (122). AC busbar support (10) according to claim 6 , wherein a gap between the current sensor (16) and an inner wall (124) of the through hole (122) is completely filled by the jacket attachment (148). AC busbar support (10) according to claim 6 , wherein the jacket attachment (148) is attached to an inner wall (124) of the through-opening (122) in such a way that the current sensor (16) is laterally spaced from the jacket attachment (148). AC busbar support (10) according to one of Claims 1 until 8th , wherein the carrier body (14) is formed by overmolding the AC busbars (12A-C) with an injection molding material. AC busbar support (10) according to one of Claims 1 until 9 , A thermally conductive insulating coating (20) being attached to an underside (150) of the AC busbar (12A-C) and/or of the carrier body (14) that faces away from the printed circuit board (22). Inverter for an electric drive of an electric vehicle or a hybrid vehicle, comprising a plurality of semiconductor switching elements which are designed to convert an input-side DC current into an output-side multi-phase AC current with a plurality of phase currents by switching the semiconductor switching elements, further comprising an AC busbar support (10 ) after one of the Claims 1 until 10 and a circuit board (22).

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