Electric drive device for powering a hybrid electric / electric vehicle, hybrid electric / electric vehicle

Abstract

Electric drive device (AV) for propelling a hybrid electric / electric vehicle, comprising: - at least two (power) electrical arrangements (EM, ST, VS, GT, LE) with parasitic capacitance, each comprising an electromagnetic shielding unit (SK, UM, SB), an electrically conductive cooling unit (KK) and / or an electrically conductive mechanical protection unit (MG); - wherein the shielding units (SK, UM, SB), the cooling units (KK) and / or the protection units (MG) are electrically connected to each other via low-impedance connections (NV) and have a common electrical connection point (AP), characterized in that - a series circuit (RS) of a resistor (R) and a coil (SD), wherein the series circuit (RS) electrically connects the connection point (AP) to the vehicle ground (KL31) of the hybrid electric / electric vehicle; - wherein the series connection (RS) has an impedance which is higher than the sum of impedances of all low-impedance connections (NV) between the shielding units (SK, UM, SB), the cooling units (KK) and the protection units (MG).

Description

Technical area:

[0001] The present invention relates to an electric drive device for driving a hybrid electric / electric vehicle and a hybrid electric / electric vehicle with said drive device. State of the art and task of the invention:

[0002] In electromobility, ever-increasing drive power, dynamic performance, and torque are required from electric drive systems. These increased requirements, along with the associated dimensions and geometry of the drive systems, result in correspondingly increasing parasitic capacitances. High parasitic capacitances, in turn, lead to high common-mode currents, which can cause malfunctions and even failures in the drive systems.

[0003] The document DE 10 2013 201 470 A1 describes an electric drive arrangement with an inverter and an electric machine, wherein the housing of the inverter and the housing of the electric machine are electrically connected via ground connections to ground connection points which are located within the respective components.

[0004] JP 2011-222 892 A describes a vehicle drive system with two body grounding conductors that are electrically insulated from each other by an insulating layer. A battery housing of the drive system is electrically connected to one of the two body grounding conductors via a grounding conductor. Housings of other components of the drive system, such as a power control unit of the drive system or a motor generator, are each electrically connected to the other body grounding conductor via additional grounding conductors.

[0005] JP 2006-217 727 A describes an electric drive system with an electric motor and an inverter for operating the electric motor. The inverter is electrically connected to the electric motor via a motor wiring harness. The system also includes a grounding wiring harness that electrically connects the electric motor housing to the inverter housing. The motor wiring harness and the grounding wiring harness are bundled together.

[0006] The document DE 199 52 886 A1 describes a multiple power converter with at least two power converter units, each of which has a local grounding point. The local grounding point of each of the at least two power converter units is connected to a common power grounding point of the at least two power converter units via a grounding impedance.

[0007] The document DE 10 2010 028 238 A1 describes an electric drive system with a capacitor module and an electric motor, wherein the capacitor module and the electric motor are each earthed to the vehicle body via an earthing conductor.

[0008] The document DE 44 21 986 A1 describes a radio interference suppression filter for electronically controlled devices with an interference suppression choke which has at least one first winding arranged on a magnetizable core, which is connected to the free ends of a live line, wherein at least one further winding is additionally arranged on the core of the interference suppression choke, which is connected to the free ends of a protective conductor and which is arranged on a first rod-shaped extension formed on the core or guided through a first bore in a bulge formed on the core.

[0009] The object of the invention is therefore to cost-effectively optimize an electrical drive arrangement with regard to the system-related parasitic capacitances. Description of the invention:

[0010] This problem is solved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0011] According to a first aspect of the invention, an electric drive arrangement for driving a hybrid electric / electric vehicle is provided.

[0012] The drive device comprises at least two (power) electrical assemblies, which, due to their design and function, have parasitic capacitances or components with parasitic capacitances. Each of the assemblies comprises one or more components with parasitic capacitances, including electromagnetic shielding units, electrically conductive cooling units, and / or electrically conductive mechanical protection units.

[0013] The drive device further comprises low-impedance connections, via which all components with parasitic capacitances, i.e., all shielding units, all electrically conductive cooling units, and / or all electrically conductive protection units, are electrically connected to one another with low impedance. The components with parasitic capacitances, namely the shielding units, the cooling units, and / or the protection units, as well as the low-impedance connections, also have a (single) common electrical connection point.

[0014] The drive device further comprises a series circuit of a resistor and a coil, wherein the series circuit electrically connects the common connection point to vehicle ground (i.e., a ground terminal) of the hybrid electric / electric vehicle.

[0015] The invention is based on the idea that the parasitic capacitances in the drive device are caused in particular by capacitive coatings on the shielding units, the electrically conductive cooling units, and / or the electrically conductive protection units of the drive device, as well as by capacitive coatings on the electrical lines between these components. These parasitic capacitances cause capacitive recharging currents as disruptive common-mode currents during rapid switching operations (of the current / voltage converters of the drive device) during operation of the drive device.

[0016] If these components are electrically contacted with the vehicle ground (vehicle body or metallic structure of the vehicle, referred to as "terminal 31 (KL31)" according to the industry standard designation) by means of the capacitive coatings (directly and individually), circuits are formed via the vehicle ground through which the common-mode currents flow and can cause malfunctions and failures in the drive device.

[0017] Within the scope of the invention, it was further recognized that a so-called common-mode equipotential structure or common-mode equipotential surface can be created by a low-impedance connection of the components with the capacitive coatings.

[0018] By forming the common-mode equipotential structure, the capacitive charge reversal currents can ideally act only in a single common electrical connection point (a so-called common-mode equipotential connection point).

[0019] This single common connection point is then electrically connected to the vehicle's ground via a series circuit of a resistor and a coil. The series circuit has an impedance that is higher than the sum of the impedances of all low-impedance connections between the shielding units, the cooling units, and the protection units.

[0020] It is important that the common-mode equipotential structure is electrically connected to the vehicle ground exclusively by means of the common common-mode equipotential connection point and via the series circuit mentioned, and is otherwise completely electrically insulated from the vehicle ground as well as all other electrically conductive components of the drive device or the vehicle.

[0021] By introducing the common-mode equipotential structure with the common common-mode equipotential connection point, the unwanted capacitive charge-reversal currents are concentrated at the common-mode equipotential connection point. Furthermore, the charge-reversal currents are suppressed by the (relatively high-impedance) series connection. This prevents the charge-reversal currents from propagating within the drive device or even beyond it.

[0022] The inductance of the coil represents a high impedance, especially for high-frequency signals, so that the common-mode equipotential structure is decoupled from the vehicle mass for high-frequency current components of the capacitive charging currents.

[0023] As a result, none of the high-frequency current components mentioned can spread via the vehicle mass into the other components of the drive system or the vehicle.

[0024] This measure prevents any electrical circuit from being excited via the vehicle's ground. The vehicle body and ground therefore no longer represent an electrical circuit capable of dissipating the disruptive charging currents or the associated disruptive charging energy.

[0025] To achieve optimal results, as many as possible, especially all, components of the drive system that have capacitive coatings and can thus generate disruptive common-mode currents during operation of the drive system should be electrically connected to each other via low-impedance connections. These components include, in particular, the electrically conductive shielding units, the electrically conductive cooling units, and the electrically conductive protection units of the drive system.

[0026] In addition, the components with capacitive coatings, i.e. the shielding units, the cooling units and / or the protection units, in particular, should be designed in such a way that the geometric extension of the low-impedance connections can be made as compact as possible.

[0027] The previously described solution for suppressing capacitive charge reversal currents (or common-mode currents) with the common-mode equipotential structure with the (single) common common-mode equipotential connection point, as well as the series connection of a resistor and a coil, has a significant cost advantage over a solution with expensive filter elements.

[0028] Electromagnetic interference and high power losses, which occur with the solution using filter elements, are largely avoided or reduced with the solution described above.

[0029] This means that the drive arrangement is cost-effectively optimized with regard to the system-related parasitic capacitances.

[0030] For example, the low-impedance connections have a combined total ohmic resistance of less than 500 µΩ (micro-ohms) or between 220 and 500 µΩ in a frequency range of up to 10 KHz (kilo-hertz).

[0031] Furthermore, the low-impedance connections have a combined insertion loss of less than 6 dB (decibels) in a frequency range of up to 1 GHz (gigahertz).

[0032] For example, the series circuit has a total resistance value of less than 100 mΩ (milli-ohms), or between 50 and 100 mΩ, or between 80 and 100 mΩ.

[0033] Furthermore, the series circuit has, for example, a total inductance value of less than 1000 µH, or less than 900 µH, or less than 800 µH.

[0034] For example, the series circuit includes a protective conductor choke (e.g. as the previously mentioned coil).

[0035] For example, the at least two arrangements comprise an electric motor, a power electronics circuit for operating the electric motor, a gate driver circuit for operating the power electronics circuit and / or electrical connections between the aforementioned arrangements.

[0036] The power electronics circuit for operating the electric motor comprises, for example, an inverter for providing phase currents for the electric motor and / or a rectifier for converting phase currents of the electric motor into direct current.

[0037] For example, the shielding units comprise at least one shielding plate for electromagnetic shielding of the power electronics circuit and / or the gate driver circuit, at least one shielding contact of the electrical connections and / or at least one sheathing of the electrical connections, in particular of a phase connector and / or a phase current busbar.

[0038] For example, the cooling units comprise at least one electrically conductive heat sink for cooling the electric motor and / or the power electronics circuit.

[0039] For example, the protection units comprise at least one electrically conductive housing part of the electric motor, the power electronics circuit and / or the gate driver circuit.

[0040] For example, the low-impedance connections comprise at least one sheet of a metal or a metal alloy, in particular of copper or a copper alloy, which is connected in a low-impedance manner to all of the shielding units, the cooling units and / or the protection units, in particular soldered or welded.

[0041] For example, the low-impedance connections comprise a braid made of carbon fibers with a metal or metal alloy embedded in the carbon fiber, especially copper or a copper alloy, which is connected to all of the shielding units, cooling units, and / or protection units in a low-impedance manner. In particular, the braid encompasses all of the shielding units, cooling units, and / or protection units and is connected to them in a low-impedance manner, e.g., soldered or welded.

[0042] The drive device further includes, for example, an intermediate circuit capacitor, which itself has parasitic capacitances. The parasitic capacitances are directly electrically connected to the low-impedance connections. Otherwise, the intermediate circuit capacitor, or its two (negative and positive) electrodes, are electrically insulated from the low-impedance connections.

[0043] The drive device further comprises, for example, a high-voltage battery and / or a control circuit for controlling the power electronics circuit and / or the gate driver circuit. The high-voltage battery and the control circuit, including their shielding units, cooling units, and / or protection units (if present), are completely electrically insulated from the shielding units, cooling units, and protection units of the aforementioned components with capacitive coatings, as well as the aforementioned low-impedance connections, except for the ground connection via the vehicle ground.

[0044] According to another aspect of the invention, a hybrid electric / electric vehicle is provided.

[0045] The hybrid electric / electric vehicle comprises a vehicle body, which serves as the vehicle ground (in English “chassis ground”, with terminal designation “KL31”).

[0046] The hybrid electric / electric vehicle further comprises a drive device as described above, wherein the drive device is electrically connected directly to the vehicle ground via the series circuit.

[0047] Advantageous embodiments of the drive device described above are, as far as possible, transferable to the above-mentioned hybrid electric / electric vehicle and are also to be regarded as advantageous embodiments of the hybrid electric / electric vehicle. Short description of the drawing:

[0048] In the following, exemplary embodiments of the invention are explained in more detail with reference to the accompanying drawings. Fig. 1 shows a schematic representation of an electric drive device AV for an electric vehicle according to an embodiment of the invention; Fig. 2 shows a further schematic representation of an electric drive device AV for an electric vehicle according to a further embodiment of the invention. Detailed description of the drawing:

[0049] The Fig. 1 shown drive device AV includes: - an electric motor EM to drive the electric vehicle; - a traction battery BT to provide power for the electric motor EM; - a power electronics circuit LE with transistor switches for converting the direct current provided by the traction battery BT into phase currents for the electric motor EM; - a gate driver circuit GT for operating the power electronics circuit LE or its transistor switch; - a control circuit SE for controlling the gate driver circuit GT and the power electronics circuit LE.

[0050] The drive device AV further comprises an intermediate circuit capacitor ZK for reducing voltage fluctuations in the drive device AV.

[0051] In addition, the drive device AV comprises electrical connections between the aforementioned components, such as traction current lines BL between the traction battery BT and the power electronics circuit LE for transmitting the battery current, a three-phase phase current busbar VS (connection frame) and a three-phase phase current connector ST between the power electronics circuit LE and the electric motor EM for transmitting the phase currents.

[0052] In this embodiment, the electric motor EM is designed as a separately excited or permanently excited synchronous machine and includes a housing MG made of an aluminum alloy to protect the electric motor EM. The housing MG includes sections that serve to cool the electric motor EM.

[0053] In this embodiment, the power electronics circuit LE comprises an inverter and a DC-DC converter. The inverter in this embodiment is formed from a B6 bridge with transistor switches, such as MOEFEST or IGTB. The DC-DC converter in this embodiment is designed as a bidirectional DC-DC converter of a known type.

[0054] In this embodiment, the gate driver circuit GT comprises circuit parts for operating the inverter and the DC-DC converter of a known type and is integrated in the power electronics circuit LE.

[0055] The power electronics circuit LE and the gate driver circuit GT have a common heat sink vs for cooling the power electronics circuit LE and the gate driver circuit GT, which heat sink is made of an aluminum alloy. Furthermore, the power electronics circuit LE and the gate driver circuit GT have shielding plates SB made of an aluminum alloy, which electromagnetically shield the power electronics circuit LE and the gate driver circuit GT from each other, or circuit components of the power electronics circuit LE and the gate driver circuit GT from each other, in a manner known to those skilled in the art.

[0056] The electrical connections between the power electronics circuit LE and the electric motor EM, namely the phase current busbar VS and the phase current connector ST, have shield contacts SK or sheaths UM made of a copper alloy for electromagnetic shielding of the electrical connections.

[0057] Due to the parasitic capacitances in the metallic housing MG, the metallic heat sink KK, the metallic shielding plates SB, and the metallic shield contacts SK or sheaths UM, resulting from the capacitive coatings of these components, capacitive charge reversal currents arise as disruptive common-mode currents during operation of the drive device AV with rapid switching operations. With high drive dynamics and a high drive power, common-mode currents with a current of 50 amperes to several hundred amperes can occur.

[0058] In order to eliminate these common-mode currents and limit their negative effects, the drive device AV comprises a braid made of carbon fibers with a copper alloy embedded in the carbon fibers, which braid encompasses the housing MG, the heat sink KK, the shielding plates SB, the shield contacts SK, and the sheaths UM, and is connected or welded to them in a low-impedance manner. The braid thus forms low-impedance connections NV between these components MG, KK, SB, UM, and SK, with the low-impedance connections NV being established by direct, extensive physical and electrical contact between the braid and these components MG, KK, SB, UM, and SK. The braid NV forms a type of equipotential "enclave" or "enclave.""Enclosure" for the aforementioned components MG, KK, SB, UM, SK, which completely electrically insulates the components MG, KK, SB, UM, SK from the remaining components of the AV drive system and the vehicle - with the exception of a single electrical connection to be described below via a series circuit to be described below.

[0059] The intermediate circuit capacitor ZK includes parasitic capacitances PK (schematically represented in the figure by a white circle on the intermediate circuit capacitor ZK) that are electrically connected directly to the low-impedance braid NV (schematically represented in the figure by a dashed line). However, the two electrodes of the intermediate circuit capacitor ZK are electrically insulated from the braid NV.

[0060] The NV braid and the low-impedance connections from the NV braid to all of the above-listed components MG, KK, SB, UM, SK, including the parasitic capacitances PK of the intermediate circuit capacitor ZK, together exhibit a total ohmic resistance of between 220 and 500 µΩ in a frequency range up to 10 kHz. Furthermore, the NV braid and the low-impedance connections from the NV braid to all components MG, KK, SB, UM, SK, PK together exhibit a total insertion loss of less than 6 dB in a frequency range up to 1 GHz.

[0061] The NV braid has an electrical connection point AP, which serves as a common common-mode equipotential connection point for establishing a single electrical connection, to be described below, between the NV braid and the vehicle ground KL31.

[0062] The drive device AV further comprises the aforementioned series circuit RS of a resistor R and a coil SD, wherein the coil SD is embodied as a protective conductor choke in this embodiment. The series circuit RS establishes the only aforementioned electrical connection from the braid NV or from the common common-mode equipotential connection point AP to the vehicle ground KL31. Thus, the braid NV and thus also the components MG, KK, SB, UM, SK, PK are electrically connected solely and exclusively via this common common-mode equipotential connection point AP and further via the series circuit RS to the vehicle ground KL31.

[0063] The inductance of the coil SD or the series circuit RS represents a high impedance, especially for high-frequency signals, so that the braid NV including all components MG, KK, SB, UM, SK, PK is decoupled from the vehicle ground KL31 for high-frequency current components of the capacitive charging currents and thus none of these high-frequency current components can spread via the vehicle ground KL31 into the components of the drive device AV and / or the vehicle and cause interference or even failures there.

[0064] In particular, the series connection RS has a higher total impedance than the total impedance of the braid NV. Specifically, the series connection RS has a total resistance value of between 80 and 100 mΩ. Furthermore, the series connection RS has a total inductance value of less than 1000 µH.

[0065] The unwanted capacitive charge reversal currents that arise during operation of the drive device AV in the above-mentioned components MG, KK, SB, UM, SK, PK collect via the low-impedance connections of the braid NV at the common-mode equipotential connection point AP.

[0066] The low-impedance design of the common-mode equipotential structure of the NV braid allows the capacitive charge reversal currents to act ideally only at a single point, i.e., at the common-mode equipotential connection point AP. This measure eliminates the possibility of excitation of any circuit via the vehicle ground KL31. The vehicle body or the vehicle's metallic structure thus no longer represents a circuit capable of conducting the disruptive charge reversal currents.

[0067] Housings, shielding elements and / or cooling units of the traction battery BT, the traction current lines BL and the control circuit SE (if these are provided) are electrically insulated from the NV braid and thus from the above-mentioned components MG, KK, SB, UM, SK, PK and are electrically connected individually or jointly directly to the vehicle ground KL31 via a ground strap.

[0068] The Fig. The drive device AV shown in Figure 2 differs from the one shown in Fig. 1 in that it also includes a high-voltage filter HF, whose parasitic capacitances are also connected to the network of low-impedance connections NV, particularly directly and electrically with low impedance. The network of low-impedance connections NV consists primarily of a heat sink KK. The parasitic capacitances PK of the intermediate circuit capacitor ZK of the drive device AV are directly connected to the heat sink KK with low impedance.

[0069] In the Fig. 2 also illustrates that high-voltage and low-voltage batteries BT, LB, data connections CAN, such as CAN bus, of the motor vehicle, as well as control circuit SE of the drive device AV are electrically insulated from the network of low-impedance connections NV.

Claims

[1] Electric drive device (AV) for driving a hybrid electric / electric vehicle, comprising: - at least two (power) electrical arrangements (EM, ST, VS, GT, LE) with parasitic capacitance, each comprising an electromagnetic shielding unit (SK, UM, SB), an electrically conductive cooling unit (KK) and / or an electrically conductive mechanical protection unit (MG); - wherein the shielding units (SK, UM, SB), the cooling units (KK) and / or the protection units (MG) are electrically connected to each other via low-impedance connections (NV) and have a common electrical connection point (AP), characterized by , that - a series circuit (RS) of a resistor (R) and a coil (SD), wherein the series circuit (RS) electrically connects the connection point (AP) to vehicle ground (KL31) of the hybrid electric / electric vehicle; - wherein the series connection (RS) has an impedance which is higher than the sum of impedances of all low-impedance connections (NV) between the shielding units (SK, UM, SB), the cooling units (KK) and the protection units (MG). [2] Drive device (AV) according to claim 1, wherein the low-impedance connections (NV) together have a total ohmic resistance of less than 500 µΩ or between 220 and 500 µΩ in a frequency range of up to 10 KHz. [3] Drive device (AV) according to claim 1 or 2, wherein the low-impedance connections (NV) together have a total insertion loss of less than 6 dB in a frequency range of up to 1 GHz. [4] Drive device (AV) according to one of the preceding claims, wherein the series circuit (RS) has a total resistance value of less than 100 mΩ, or between 50 and 100 mΩ, or between 80 and 100 mΩ. [5] Drive device (AV) according to one of the preceding claims, wherein the series circuit (RS) has a total inductance value of less than 1000 µH, or less than 900 µH, or less than 800 µH. [6] Drive device (AV) according to one of the preceding claims, wherein the series circuit (RS) comprises a protective conductor choke (SD). [7] Drive device (AV) according to one of the preceding claims, wherein the at least two arrangements comprise an electric motor (EM), a power electronics circuit (LE) for operating the electric motor (EM), a gate driver circuit (GT) for operating the power electronics circuit (LE) and / or electrical connections (ST, VS) between the at least two arrangements (EM, GT, LE). [8] Drive device (AV) according to one of the preceding claims, wherein the shielding units comprise at least one shielding plate for electromagnetic shielding of the power electronics circuit (LE) and / or the gate driver circuit (GT), and / or at least one shielding contact (SK) of the electrical connections (ST, VS), and / or at least one sheathing (UM) of the electrical connections (ST, VS). [9] Drive device (AV) according to one of the preceding claims, wherein the cooling units comprise at least one electrically conductive heat sink (KK) for cooling the electric motor (EM) and / or the power electronics circuit (LE). [10] Drive device (AV) according to one of the preceding claims, wherein the protective units comprise at least one electrically conductive housing part (MG) of the electric motor (EM), the power electronics circuit (LE) and / or the gate driver circuit (GT). [11] Drive device (AV) according to one of the preceding claims, wherein the low-impedance connections (NV) comprise at least one sheet of a metal or a metal alloy, in particular of copper or a copper alloy, which is connected in a low-impedance manner to all of the shielding units (SK, UM, SB), the cooling units (KK) and / or the protection units (MG). [12] Drive device (AV) according to one of the preceding claims, wherein the low-impedance connections (NV) comprise a braid of carbon fibers with a metal or a metal alloy embedded in the carbon fiber, in particular copper or a copper alloy, which is connected in a low-impedance manner to all of the shielding units (SK, UM, SB), the cooling units (KK) and / or the protection units (MG). [13] Drive device (AV) according to claim 1, further comprising an intermediate circuit capacitor (ZK) whose parasitic capacitances are directly electrically connected to the low-impedance connection (NV). [14] Drive device (AV) according to one of the preceding claims, further comprising a high-voltage battery (BT) and / or a control circuit (SE) for controlling the power electronics circuit (LE) and / or the gate driver circuit (GT), wherein all of the high-voltage battery (BT) and / or the control circuit (ST) are not electrically contacted with the shielding units (SK, UM, SB), the cooling units (KK), the protection units (MG) and / or the low-impedance connections (NV). [15] Hybrid electric / electric vehicle, comprising: - a vehicle body as vehicle mass (KL31); - a drive device (AV) according to one of the preceding claims, wherein the drive device (AV) is electrically connected to the vehicle mass (KL31) via the series circuit (RS).

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