DE102022204330A1 - High-voltage drive system for a vehicle and vehicle with a high-voltage drive system - Google Patents

Abstract

The invention relates to a high-voltage drive system for a vehicle with at least one electric drive energy storage (12), which is functionally connected via an electrical line system to at least one drive motor (14, 16) for driving at least one drive wheel in such a way that the electrical energy of the drive energy storage ( 12) can be used to drive the at least one drive wheel, with at least one inverter (22, 28) and at least one first capacitor (20) being arranged between the drive energy storage (12) and the drive wheel, with at least one second capacitor (20) being arranged in the electrical line system ( 26) is arranged and wherein the electrical line system is at least partially formed from an electrical line (34) with a first conductor (38) and at least one second conductor (40), which are arranged adjacent to one another within a jacket (44) enclosing them and through an insulation layer (42) are separated from one another, the insulation layer (42) having a dielectric strength of at least 150 kV/mm, which preferably has a maximum thickness of 125 μm. The invention further relates to a vehicle with a high-voltage drive system (10).

Description

The invention relates to a high-voltage drive system for a vehicle according to the preamble of claim 1 and a vehicle with such a high-voltage drive system. In particular, the invention relates to vehicles in the form of motor vehicles, preferably motor vehicles, which have an all-wheel drive with an electric front and an electric rear drive.

Out of FR 1 358 913 A an electrical insulator with high mechanical tensile strength is known, which is intended to be used in connection with electrical high-voltage, medium-voltage and low-voltage lines of power networks. No reference is made to high-voltage drive systems of vehicles or to vehicles with such drive systems.

Out of DE 10 2015 213 428 A1 is an electrical conductor device for transmitting electrical current over two separate phases with a connection for the first and the second phase at one end of the electrical conductor device and a connection for the first and second phase of the electrical conductor device at a second end of the conductor. The electrical conductor device has a plurality of conductive layers arranged parallel to one another, which are each separated from one another by a dielectric, which are alternately assigned to either the first or the second phase and via which, depending on their assignment to a phase, either current of the first or current of the second Phase can be transferred between the connections at the first and second ends of the conductor. The electrical conductor device should preferably have between 4 and 2000 conductive layers and is intended in particular for use in photovoltaic systems. The use of the electrical conductor device is said to have the advantage that a capacitor - which takes up a relatively large amount of space - is dispensed with or can be made smaller. No reference is made to high-voltage drive systems of vehicles or to vehicles with such drive systems.

In the case of high-voltage drive systems for vehicles known from practice according to the preamble of claim 1, resonance phenomena occur, especially when it comes to high-voltage drive systems of vehicles with electric front and rear drive. Resonances can arise in particular through the interaction of the inductance coating (L`) of electrical lines (also called traction lines or HV lines) of such high-voltage drive systems with the intermediate capacitors (C1, C2) of the two drive inverters of two drive motors. The resonances lead to high reactive currents that oscillate back and forth between the two drive motors at the resonance frequency. This creates magnetic fields with the same frequency and additional losses across the electrical line. Due to their electromagnetic force on metal body structures, the magnetic fields can lead to mechanical excitation, which in turn leads to undesirable acoustic abnormalities in the vehicle. Both are disadvantageous and reduce the range or require additional measures to shield the fields.

The electrical lines known from the prior art are made up of round conductors and can be used shielded or unshielded. In practice, the inductance (L`) for a shielded double cable is often around 0.4 µH/m and for unshielded double cables it is around 0.7 µH/m. Regardless of whether shielded or unshielded electrical cables are used, at certain capacitance values of the intermediate circuit capacitors, resonances occur in the range that is easily audible to most people, i.e. resonances with a frequency between 20 Hz and 15 kHz, in particular or between 20 Hz and 10 kHz.

An increase in the line inductance causes the resonance frequency to shift towards lower frequencies and may therefore be perceived as even more disturbing. In most cases, an adjustment of the capacity values cannot be implemented for functional reasons of the drives and/or it is very cost-intensive and therefore not economical.

The resonance frequency of a system as outlined above can be determined in a simplified manner, i.e. without taking into account the influence of a drive energy storage in the form of a high-voltage battery, as follows: $$f_{res}=\frac{1}{2\pi }\cdot \sqrt{\frac{1}{L\text{'}}\left(\frac{1}{C_1}+\frac{1}{C_2}\right)}$$

L' is the inductance of the electrical line, C ₁ is the capacity of the first capacitor and C ₂ is the capacity of the second capacitor.

The invention is based on the object of improving a high-voltage drive system for a vehicle according to the preamble of claim 1 and a vehicle with such a high-voltage drive system in such a way that the above-mentioned acoustic abnormalities in the hearing available area can be avoided or at least largely reduced.

The problem is solved according to the invention with the features of the independent claims. Further practical embodiments and advantages of the invention are described in connection with the dependent claims.

A high-voltage drive system according to the invention for a vehicle comprises at least one electrical drive energy storage, which is functionally connected via an electrical line system to at least one drive motor for driving at least one drive wheel in such a way that the electrical energy of the drive energy storage can be used to drive the at least one drive wheel. At least one inverter and at least one first capacitor are arranged between the drive energy storage and the drive wheel, with at least one second capacitor being arranged in the electrical line system and the electrical line system being at least partially formed from an electrical line with a first conductor and at least one second conductor which are arranged adjacent to one another within a jacket enveloping them and are separated from one another by an insulating layer. The insulation layer has a dielectric strength of at least 150 kV/mm. The dielectric strength values mentioned in this document refer to measurements according to IEC 60243. The design makes it possible to realize an electrical cable with - compared to cables known from the technical field of high-voltage drive systems - significantly reduced inductance (L`), in particular in that the distance between the electrical conductors within an electrical line can be kept very small. By means of the insulation layer designed as mentioned above, voltage flashovers or short circuits are avoided. With the high-voltage drive system according to the invention, the resulting resonance frequencies, which were still in the audible range with electrical lines known from the prior art (e.g. at approximately 6 kHz), can be in a frequency range above 10 kHz, above 15 kHz or even above from 20 kHz so that they can only be heard by a few people or even no one at all. In a high-voltage drive system according to the invention, additional acoustic measures can be dispensed with because disruptive resonance frequencies are avoided. The efficiency of such a system is also increased because the compensating currents are reduced. The capacitors, which are intended for drive motors, can also be designed to be smaller in high-voltage drive systems according to the invention. Due to reduced magnetic fields, a high-voltage drive system according to the invention can even be used to lay electrical cables (HV cables) in the vehicle interior.

For the sake of completeness, it should be noted that the electrical line system is preferably formed entirely from an electrical line with a first conductor and at least one second conductor, which are arranged adjacent to one another within a jacket enveloping them and are separated from one another by an insulating layer, the insulating layer being a Dielectric strength of at least 150 kV/mm. The same applies to all of the more detailed technical features described below. An electrical line of the high-voltage drive system according to the invention preferably has the corresponding features over its entire length. If several electrical lines are provided in the high-voltage drive system according to the invention, each electrical line preferably has these technical features.

In a practical embodiment of a high-voltage drive system according to the invention, the insulation layer is made of polyimide. Polyimide exists in various embodiments, in particular with dielectric strengths of 150 kV/mm up to 310 kV/mm. Preferably, the insulation layer is realized with a dielectric strength of at least 180 kV/mm, more preferably at least 210 kV/mm and particularly preferably at least 250 kV/mm or even 280 kV/mm.

In the case of an insulation layer made of polyimide, the above-mentioned values for the dielectric strength can be achieved using a polyimide film with a maximum thickness of 125 µm. A polyimide film with a thickness of a maximum of 100 μm, more preferably a maximum of 75 μm and particularly preferably a maximum of 50 μm is preferably used.

In principle, the jacket can be made of the same material as the at least one insulation layer or possibly also several insulation layers. However, it is preferred if the jacket is made of a different material than the insulation layer. Thermoplastic plastics are particularly well suited for the jacket, in particular plastics by means of which the jacket can be formed by injection molding. Regardless of how the jacket is manufactured, polyethylene (PE) is also referred to as a particularly suitable material for the jacket, as this material is particularly abrasion-resistant, water-repellent and mechanically stable.

The three line variants described below are particularly suitable for implementing the invention.

According to the first variant, the electrical line is formed from exactly two conductors and is designed as a flat conductor with a rectangular cross section, the first conductor and the second conductor being arranged next to one another and separated from one another by an insulating layer which is linear in cross section.

According to the second variant, the electrical line is formed from more than two conductors and is designed as a flat conductor with a rectangular cross section, with two adjacent conductors being separated from one another by an insulation layer with a linear cross section.

For the purposes of the invention, a flat conductor is understood to mean, in particular, those conductors which have a conductor width in cross section that is significantly larger than the conductor height, the conductor width being in particular at least 3 times, at least 4 times, at least 5 times or is at least 10 times the height of the ladder.

According to the third variant, the electrical line is formed from exactly two conductors and is designed as a coaxial conductor with a round cross-section, the first conductor being arranged surrounding the second conductor and the first conductor and the second conductor being separated from one another by an insulating layer with a round cross-section. Preferably, the first conductor and the second conductor each have an oval or circular cross-sectional shape. The inner second conductor preferably has an oval or circular solid profile, while the outer first conductor preferably has an annular hollow profile which encloses the solid profile of the second conductor.

In a further practical embodiment of a high-voltage drive system according to the invention, a first drive motor and a second drive motor are provided for driving at least two different drive wheels, with a second inverter and the second capacitor being provided to supply the second drive wheel with energy. In practice, the resonance problems described above occur particularly frequently with such high-voltage drive systems, so that the design according to the invention is of particular use, particularly in connection with such high-voltage drive systems.

In conjunction with a high-voltage drive system with a first drive motor and a second drive motor, the first drive motor is preferably part of a front-wheel drive and the second drive motor is part of a rear-wheel drive or vice versa.

The invention also relates to vehicles with a high-voltage drive system as described above, in which the second capacitor is part of an air conditioning unit, a voltage converter or a second drive motor. In this context, it is particularly pointed out that a second capacity does not necessarily have to be caused by a second drive motor, but also by an air conditioning unit and/or a voltage converter, for example to support a 12V vehicle electrical system, in the form of a corresponding capacitor with a high voltage according to the invention -Drive system can be interconnected. In this regard, it is particularly pointed out that capacitors in the sense of the invention are particularly those with a capacity of at least 10 µF. Such capacitances, especially between 10 µF and 100 µF, are particularly common for air conditioning devices or voltage converters. A vehicle according to the invention or a high-voltage drive system according to the invention preferably has two capacitors with capacities of at least 100 µF, in particular in the form of test inverters (PWR) of drive motors. The capacitances of capacitors of high-voltage drive systems according to the invention are preferably between 100 µF and 1,000 mF, particularly preferably between 300 µF and 800 µF.

• 1 eine schematische Darstellung des Aufbaus eines erfindungsgemäßen Hochvolt-Antriebssystems mit einem Antriebsenergiespeicher und zwei funktional damit verbundenen Antriebsmotoren,
• 2 eine ersten Ausführungsform einer als Flachleiter ausgebildeten elektrischen Leitung mit zwei Leitern in einer Querschnittdarstellung,
• 3 eine zweite Ausführungsform einer als Flachleiter ausgebildeten elektrischen Leitung mit drei Leitern in einer Querschnittdarstellung und
• 4 eine dritte Ausführungsform mit einer als Koaxialleiter ausgebildeten elektrischen Leitung mit zwei Leitern in einer Querschnittdarstellung.

Further practical embodiments of the invention are described below in connection with the drawings. Show it:

• 1 a schematic representation of the structure of a high-voltage drive system according to the invention with a drive energy storage and two drive motors functionally connected to it,
• 2 a first embodiment of an electrical line designed as a flat conductor with two conductors in a cross-sectional view,
• 3 a second embodiment of an electrical line designed as a flat conductor with three conductors in a cross-sectional view and
• 4 a third embodiment with an electrical line designed as a coaxial conductor with two conductors in a cross-sectional view.

1 shows a schematic representation of the structure of a high-voltage drive system 10 according to the invention with a drive energy storage 12, a first drive motor 14 and a second drive motor 16. Front wheels, not shown, of a vehicle, also not shown, are driven via the first drive motor 14. Rear wheels of the vehicle, not shown, are driven via the second drive motor 16.

The drive energy storage 12 is a high-voltage battery (HV battery) that provides a voltage of more than 200 V, in particular a voltage between 300 V and 1,200 V, preferably between 350 V and 1,000 V.

A first EMC filter 18, a first capacitor 20 with the capacity C ₁ and a first inverter 22 are arranged between the drive energy storage 12 and the first drive motor 14.

A second EMC filter 24, a second capacitor 26 with the capacity C ₂ and a second inverter 28 are arranged between the drive energy storage 12 and the second drive motor 16.

The unit consisting of the first EMC filter 18, the first capacitor 20, the first inverter 22 and the first drive motor 14 can be viewed as a front wheel drive unit 30.

The unit consisting of the second EMC filter 24, the second capacitor 26, the second inverter 28 and the second drive motor 16 can be viewed as a rear wheel drive unit 32.

The electrical lines 34a, 34b with the line inductance K leading from the drive energy storage 12 to the front wheel drive unit 30 and to the rear wheel drive unit 32 are symbolically represented by a rectangle 36. In the embodiment shown, the lines are metallic lines, i.e. lines made of a metallic base material.

In the 2 until 4 three different embodiments of electrical conductors 34a, 34b are shown, as in particular in one, as in 1 The high-voltage drive system 10 outlined is installed.

In the 2 The first embodiment shown is an electrical line designed as a flat conductor with a first conductor 38 and a second conductor 40, the first conductor 38 being in particular a minus line and the second conductor 40 being in particular a plus line. Both the first conductor 38 and the second conductor 40 have a basic shape that is rectangular in cross section. An insulating layer 42 with a linear cross-section is arranged between the first conductor 38 and the second conductor 40. The insulation layer 42 is formed from polyimide. The first conductor 38 and the second conductor 40 are formed from a material that has an electrical conductivity of at least 30 MS/m, in particular aluminum or copper. In the exemplary embodiment shown, the insulation layer 42 has a thickness that is greater than 1 μm and preferably less than 125 μm. Preferred values for the thickness of the insulation layer 42 are between 25 μm and 100 μm. In the exemplary embodiment, the insulation layer 42 is formed from polyimide in the form of a polyimide film.

On the outside, the first conductor 38 and the second conductor 40 are completely covered by a jacket 44. In the embodiment shown, this is made of polyethylene.

In the 3 The embodiment shown essentially corresponds to that in 2 embodiment shown. However, the second conductor 40 has one compared to that in 2 Embodiment shown reduces ladder height by approximately 50 percent. In addition, there is a third conductor 46, which is arranged on the opposite side of the second conductor 40, resulting in a sandwich construction. If - as in the embodiment according to 2 the first conductor 38 is a negative line, the second conductor 40 and the third conductor 46 are preferably each a plus line. The above applies accordingly to the insulation layers 42 and the covering 44, which is in conjunction with 2 was described.

4 shows a further embodiment with a first conductor 38 and a second conductor 40, which is a coaxial line. Accordingly, the first conductor 38 and the second conductor 40 each have a circular cross-sectional shape, with the first conductor 38 being arranged surrounding the second conductor 40. The second conductor 40 has a circular solid profile, the first conductor 38 has a geometry that is circular in cross section.

The features of the invention disclosed in the present description, in the drawings and in the claims can be essential for the implementation of the invention in its various embodiments, both individually and in any combination. The invention can be varied within the scope of the claims and taking into account the knowledge of the responsible person skilled in the art.

Reference symbol list

10

High-voltage drive system

12

Drive energy storage

14

first drive motor

16

second drive motor

18

first EMC filter

20

first capacitor

22

first inverter

24

second EMC filter

26

second capacitor

28

second inverter

30

Front wheel drive unit

32

Rear wheel drive unit

34a,b

electrical line

36

rectangle

38

first conductor (minus line)

40

second conductor (plus line)

42

insulation layer

44

Coat

46

third leader

C1

Capacity of the first capacitor

C2

Capacity of the second capacitor

Z

line resistance

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The 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

• FR 1358913 A [0002]
• DE 102015213428 A1 [0003]

Claims (10)

High-voltage drive system for a vehicle with at least one electrical drive energy storage (12), which is functionally connected via an electrical line system to at least one drive motor (14, 16) for driving at least one drive wheel in such a way that the electrical energy of the drive energy storage (12) is used for driving of the at least one drive wheel can be used, with at least one inverter (22, 28) and at least one first capacitor (20) being arranged between the drive energy storage (12) and the drive wheel, with at least one second capacitor (26) being arranged in the electrical line system and wherein the electrical line system is at least partially formed from an electrical line (34) with a first conductor (38) and at least one second conductor (40), which are arranged adjacent to one another within a jacket (44) enclosing them and through an insulating layer (42 ) are separated from each other, characterized in that the insulation layer (42) has a dielectric strength of at least 150 kV/mm. High-voltage drive system according to the preceding claim, characterized in that the insulation layer (42) is formed from polyimide. High-voltage drive system according to one of the preceding claims, characterized in that the insulation layer (42) has a maximum thickness of 125 µm. High-voltage drive system according to one of the preceding claims, characterized in that the jacket (44) is formed from a different material than the insulation layer (42). High-voltage drive system according to one of the preceding claims, characterized in that the electrical line (34) is formed from exactly two conductors (38, 40) and is designed as a flat conductor with a rectangular cross section, the first conductor (38) and the second conductor ( 40) are arranged next to each other and separated from one another by an insulation layer (42) which is linear in cross section. High-voltage drive system according to one of the Claims 1 until 3 , characterized in that the electrical line (34) is formed from more than two conductors (38, 40, 46) and is designed as a flat conductor with a rectangular cross section, with two adjacent conductors (38, 40) being covered by an insulation layer (38, 40) which is linear in cross section ( 42) are separated from each other. High-voltage drive system according to one of the Claims 1 until 3 , characterized in that the electrical line (34) is formed from exactly two conductors (38, 40) and is designed as a coaxial conductor with a round cross-section, the first conductor (38) being arranged surrounding the second conductor (40) and the first conductor (38) and the second conductor (40) are separated from each other by an insulating layer (42) which is round in cross section. High-voltage drive system according to one of the preceding claims, characterized in that a first drive motor (14) and a second drive motor (16) are provided for driving at least two different drive wheels, a second inverter (28) and the second capacitor (26) are provided. High-voltage drive system according to the preceding claim, characterized in that the first drive motor (14) is part of a front wheel drive unit (30) and the second drive motor (16) is part of a rear wheel drive unit (32) or vice versa. Vehicle with a high-voltage drive system (10) according to one of the Claims 1 until 9 , characterized in that the second capacitor (26) is part of an air conditioning device, a voltage converter or a second drive motor (16).

Images