US-12628277-B2 - Power circuit assembly for a vehicle

US12628277B2US 12628277 B2US12628277 B2US 12628277B2US-12628277-B2

Abstract

A power circuit assembly for a vehicle. The power circuit assembly includes a first circuit carrier on which at least two power semiconductor switches are arranged; at least one energy store which provides a high voltage and which can be discharged via at least one discharge resistor; a second circuit carrier on which at least two driver circuits are arranged, which are respectively assigned to one of the at least two power semiconductor switches; and a flexible printed circuit board which includes at least one line and electrically connects the first circuit carrier and the second circuit carrier to one another. An inverter including the power circuit assembly for a vehicle is also described.

Inventors

Andreas Speinle
Armin Ruf
Manuel Wild
Walter Von Emden

Assignees

ROBERT BOSCH GMBH

Dates

Publication Date: 20260512
Application Date: 20220802
Priority Date: 20210811

Claims (13)

1 . A power circuit assembly for a vehicle, comprising: a first circuit carrier on which at least two power semiconductor switches are arranged; at least one energy store configured to provide a high voltage and which can be discharged via at least one discharge resistor; a second circuit carrier on which at least two driver circuits are arranged, which are respectively assigned to one of the at least two power semiconductor switches; and a flexible printed circuit board which includes at least one line and electrically connects the first circuit carrier and the second circuit carrier to one another; wherein the at least one discharge resistor is configured as a conductor structure and is integrated into the flexible printed circuit board, wherein the flexible printed circuit board is thermally coupled to a heat sink in a region of the at least one conductor structure so that heat from resistor power losses of the at least one conductor structure is transferred directly to the heat sink.
2 . The power circuit assembly according to claim 1 , wherein the at least one conductor structure is configured as a meandering structure or as a zigzag structure or as a spiral structure or as a strip structure.
3 . The power circuit assembly according to claim 1 , wherein the flexible printed circuit board includes multiple layers, wherein the at least one conductor structure extends over several layers.
4 . The power circuit assembly according to claim 1 , wherein the flexible printed circuit board is connected to the heat sink at least in the region of the at least one conductor structure by soldering or by gluing or by sintering or via an outer thermally conductive coating of the flexible printed circuit board.
5 . The power circuit assembly according to claim 1 , wherein the first circuit carrier is configured as an AMB substrate or as a DBC substrate.
6 . The power circuit assembly according to claim 5 , wherein the first circuit carrier is thermally connected to a cooling device via a first metal layer.
7 . The power circuit assembly according to claim 1 , wherein the flexible printed circuit board is connected to the heat sink at least in the region of the at least one conductor structure via an outer thermally conductive coating, and wherein the outer thermally conductive coating of the flexible printed circuit board is connected to a second metal layer of the first circuit carrier as the heat sink.
8 . The power circuit assembly according to claim 1 , wherein the flexible printed circuit board is electrically connected to the second circuit carrier via a transition piece and at least one contacting region.
9 . The power circuit assembly according to claim 1 , wherein a discharge switch arranged on the second circuit carrier is configured to electrically connect the at least one discharge resistor to the at least one energy store for active discharging.
10 . The power circuit assembly according to claim 1 , wherein a voltage transformer, which converts a high voltage of the at least one energy store to a low voltage of less than 60 volts, is arranged on the second circuit carrier.
11 . The power circuit assembly according to claim 10 , wherein the flexible printed circuit board is electrically connected to the second circuit carrier via a transition piece and at least one contacting region, wherein a discharge switch arranged on the second circuit carrier is configured to electrically connect the at least one discharge resistor to the at least one energy store for active discharging, and wherein the discharge switch is arranged between a low-voltage output of the voltage transformer and the at least one contacting region of the flexible printed circuit board.
12 . The power circuit assembly according to claim 11 , wherein a measuring resistor is arranged between the discharge switch and the at least one contacting region of the flexible printed circuit board and can be used to measure a current discharge current.
13 . An inverter for an AC electric machine, wherein the inverter is looped in between a DC voltage supply and the AC machine and comprises: at least one power circuit assembly, including: a first circuit carrier on which at least two power semiconductor switches are arranged, at least one energy store configured to provide a high voltage and which can be discharged via at least one discharge resistor, a second circuit carrier on which at least two driver circuits are arranged, which are respectively assigned to one of the at least two power semiconductor switches, and a flexible printed circuit board which includes at least one line and electrically connects the first circuit carrier and the second circuit carrier to one another, wherein the at least one discharge resistor is configured as a conductor structure and is integrated into the flexible printed circuit board, wherein the flexible printed circuit board is thermally coupled to a heat sink in a region of the at least one conductor structure so that heat from resistor power losses of the at least one conductor structure is transferred directly to the heat sink.

Description

FIELD The present invention relates to a power circuit assembly for a vehicle, which can in particular be used in an inverter for electric machines. In addition, the present invention relates to an inverter for an AC electric machine comprising such a power circuit assembly. BACKGROUND INFORMATION Electrically driven vehicles, such as battery electric vehicles, hybrid vehicles or fuel cell vehicles, share the challenge of safely handling high voltages of, for example, 400V or 800V in the vehicle. Since voltages above 60 volts are hazardous to humans, safe handling of high-voltage components, for example during maintenance or in the case of crashes, is an important aspect. There are therefore various safety requirements that dictate that energy storage elements, for example DC coupling capacitors with a capacity of several hundred microfarads, should be discharged to safe voltage values below 60 volts within specific time periods. For this purpose, various circuit assemblies for discharging energy stores are available, which comprise active and passive discharge components. Typically, a circuit with wiring, plug connectors, and passive ohmic resistors is used. Alternatively, insulating substrates with printed thin-layer resistors or printed thick-layer resistors are used, which are fastened to a heat sink. For example, a circuit assembly, which can be used in a power converter, for discharging an electrical energy store is described in German Patent Application No. DE 10 2012 218 604 A1. The circuit assembly comprises, for uncontrolled, passive discharging of the energy store, a first discharge current path which extends from a first, positive power connection of the energy store to a second, negative power connection of the energy store and comprises a first discharge resistor which limits the current in the first discharge current path. For active discharging of the energy store, the circuit assembly comprises a second discharge current path which extends from the positive power connection of the energy store to the negative power connection of the energy store in parallel to the first discharge current path and comprises a second discharge resistor which can be connected via a controllable semiconductor switch and limits the current in the first discharge current path. The discharging speed of the respective discharge current path can be set via resistance values of the two discharge resistors, wherein the first discharge resistor has a significantly higher resistance value than the second discharge resistor. The two discharge resistors are each designed as a thick-layer resistor, which is printed from resistor paste onto a ceramic carrier material in a screen printing process. In this case, the two thick-layer resistors of the first and the second discharge resistor are monolithically formed on one and the same carrier material. SUMMARY A power circuit assembly for a vehicle with features of the present invention may have the advantage that by integrating the at least one discharge resistor as a conductor structure into a flexible printed circuit board, which electrically connects a first circuit carrier of the power circuit assembly to a second circuit carrier of the power circuit assembly by means of at least one line, already existing structural elements of the power circuit assembly can be used to discharge at least one energy store by converting the charged electrical energy into thermal energy within a predetermined time period to a voltage value of below 60 volts, which is harmless to humans. Thus, the at least one discharge resistor is no longer a single discrete element or substrate but a conductor structure integrated into the flexible printed circuit board. This results in system advantages in terms of module size (installation space) and integration density since they are not or only insignificantly extended to implement the discharge function. Embodiments of the present invention provide a power circuit assembly for a vehicle, which assembly comprises a first circuit carrier on which at least two power semiconductor switches are arranged; at least one energy store which provides a high voltage and can be discharged via at least one discharge resistor; a second circuit carrier on which at least two driver circuits are arranged, which are respectively assigned to one of the at least two power semiconductor switches; and a flexible printed circuit board which comprises at least one line and electrically connects the first circuit carrier and the second circuit carrier to one another. In this case, the at least one discharge resistor is designed as a conductor structure and is integrated into the flexible printed circuit board. The flexible printed circuit board is thermally coupled to a heat sink in the region of the at least one conductor structure so that heat from resistor power losses of the at least one conductor structure is transferred directly to the heat sink. In addition, according to