DE102016223770A1 - Cable, method of making the cable and power supply system - Google Patents

Abstract

A cable is specified. The cable (1) comprises at least two conductors (3, 5), a magnetic shield (7) and an electrical shield (8). Here, the at least two conductors (3, 5) with their main extension axes parallel, adjacent to each other and formed electrically isolated from each other. The magnetic shield (7) surrounds the at least two conductors (3, 5) at least partially along a circumference of the cable (1). In addition, the electrical shield (8) surrounds the at least two conductors (3, 5) and the magnetic shield (7). Furthermore, a corresponding method for the production of the cable and a power supply system for a vehicle are specified, which comprises the cable (1).

Description

The invention relates to a cable, a method for producing the cable and a power supply system for a vehicle.

Electrical cables can be used in some applications to carry high currents at high frequencies. Electromagnetic shielding of the cables can lead to losses, thermal overload or rigidity of the cables.

The object underlying the invention is to provide a cable, a corresponding method of manufacture and a power supply system, which contribute to minimize losses in the use of the cable in the aforementioned applications and to ensure flexibility of the cable ,

The object is solved by the independent claims. Advantageous embodiments are characterized in the subclaims.

According to a first aspect, the invention relates to a cable comprising at least two conductors, a magnetic shield and an electrical shield. The at least two conductors are arranged with their main extension axes parallel, adjacent to each other and electrically isolated from each other. The magnetic shield surrounds the at least two conductors at least partially along a circumference of the cable. In addition, the electrical shield surrounds the at least two conductors and the magnetic shield.

This advantageously contributes to avoiding induction of currents in the electrical shielding of the cable. In particular, even when using the cable at high current and high frequency is possible to ensure a shielding of the magnetic field and the electric field and to keep losses low.

Under the magnetic shield in this context is a sheath of the cable with a high magnetic conductivity to understand. The magnetic shield has in particular a low electrical conductivity. The magnetic shield can be, for example, a polymer film in which ferrite powder is introduced.

Under the electrical shielding is also a coat of cable with a high electrical conductivity to understand. The electrical shield has in particular a low magnetic conductivity. The electrical shielding may be, for example, a braided shield.

For electrical insulation of the at least two conductors from each other, these are each surrounded in particular by an insulation.

Due to the magnetic shield, a thickness of the electrical shielding and / or a distance of the electrical shielding to the at least two conductors can be kept low. Advantageously, this contributes to a small diameter of the cable and a mechanical flexibility thereof. In particular, this makes a simple, robust line construction possible. On a contacting of the magnetic shield can also be dispensed with, so that in this context simple plug-in systems can be used.

In an advantageous embodiment according to the first aspect, the at least two conductors have a diameter d> 1 mm. In particular, the conductor is not a signal conductor.

Advantageously, this allows the leadership of high currents through the cable. In particular, the cable is designed to carry currents in the range of 10 A to 200 A, in particular 50 A. The diameter of the cable can in this context be in particular 1.0 mm ≦ d ≦ 25 mm.

In a further advantageous embodiment according to the first aspect, the magnetic shield has a relative magnetic permeability μ _r > 2.

Advantageously, this allows a shielding of the magnetic field. A thickness of the electrical shield and / or a distance of the electrical shield from the at least two conductors can be kept low. In particular, the relative magnetic permeability of the magnetic shield can be μ _r > 5, preferably μ _r > 10.

In a further advantageous embodiment according to the first aspect, the at least two conductors have an insulation with a thickness b _iso . In addition, the magnetic shield has a thickness b _screen and a relative magnetic permeability μ _r . For the thickness b _{iso of} the insulation, the thickness b _{screen of} the magnetic shield and the relative magnetic permeability μ _{r of} the magnetic shield, the following applies: $${\mathrm{\mu }}_{\text{r}}{\text{* b}}_{\text{umbrella}}{\text{/ b}}_{\text{iso}}>\mathrm{17th}$$

Advantageously, this allows a targeted design of the cable to a corresponding application. Advantageously, the cable can be optimized with respect to the supplying current, frequency and voltage as well as a geometry of the at least two conductors. A reduction of the magnetic field by the magnetic shielding under the above equation is at least a factor of 5.

Preferably, the factor of the reduction is 10 or more. For the thickness b _{Iso of} the insulation, the thickness b _{screen of} the magnetic shielding and the relative magnetic permeability μ _{r of} the magnetic shield, then: $${\mathrm{\mu }}_{\text{r}}{\text{* b}}_{\text{umbrella}}{\text{/ b}}_{\text{iso}}>\mathrm{37th}$$

At μ _r = 10, a ratio of the thickness b _{screen of} the magnetic shield to the thickness b _{iso of} the insulation is 3.7.

In a further advantageous embodiment according to the first aspect, a thickness b _{screen of} the magnetic shield along a circumference of the cable and / or a relative magnetic permeability μ _{r of} the magnetic shield varies along a circumference of the cable.

Advantageously, this makes it possible to increase an effective length of the magnetic field flux through a respective isolation of the at least two conductors. Thus, it is contributed to increase a respective magnetic resistance and to reduce the magnetic field flux. An average thickness b _{screen of} the magnetic shield can be kept low in this case with advantage.

In a further advantageous embodiment according to the first aspect, the magnetic shield has a recess which is arranged in a region between the main extension axes of the at least two conductors. The recess tapers towards an exterior of the cable.

Advantageously, this makes it possible to increase an effective length of the magnetic field flux through a respective isolation of the at least two conductors. Thus, it is contributed to increase a respective magnetic resistance and reduce the magnetic field flux. The thickness b _{screen of} the magnetic shield can be kept low in this case with advantage.

In a further advantageous embodiment according to the first aspect, the electrical shield is embedded in a jacket of the cable, which encloses the at least two conductors and the magnetic shielding. The jacket may in particular be a protective jacket of the cable.

In a further advantageous embodiment according to the first aspect, the magnetic shield completely surrounds the at least two conductors along the circumference of the cable.

In a further advantageous embodiment according to the first aspect, the magnetic shield is formed electrically insulating.

In a further advantageous embodiment according to the first aspect, the magnetic shield comprises or consists of a polymer, in which ferrite powder is introduced into the polymer.

Advantageously, this contributes to a small diameter of the cable as well as a mechanical flexibility and at the same time makes it possible to ensure a shielding of the magnetic field. The polymer may be formed in particular as a film.

• a) Bereitstellen wenigstens zweier Leiter, die mit ihren Haupterstreckungsachsen parallel, benachbart zueinander angeordnet und voneinander elektrisch isoliert ausgebildet sind;
• b) Bereitstellen einer zylindrisch geformten, magnetischen Schirmung sowie einer elektrischen Schirmung. Die magnetische Schirmung weist dabei eine Durchgangsöffnung entlang ihrer Haupterstreckungsachse auf;
• c) Überschieben der magnetischen Schirmung, indem die wenigstens zwei Leiter relativ bezüglich der magnetischen Schirmung parallel der Haupterstreckungsachsen durch die Durchgangsöffnung bewegt werden. Die relative Bewegung erfolgt hierbei derart, dass die wenigstens zwei Leiter sich in der Durchgangsöffnung erstrecken und die magnetische Schirmung die wenigstens zwei Leiter vollständig entlang eines Umfangs des Kabels umgibt; und
• d) Aufbringen der elektrischen Schirmung, so dass die elektrische Schirmung die wenigstens zwei Leiter und die magnetische Schirmung umgibt.

According to a second aspect, the invention relates to a method for producing a cable according to the first aspect. The method comprises the steps:

• a) providing at least two conductors, which are arranged with their main extension axes parallel, adjacent to each other and electrically isolated from each other;
• b) providing a cylindrically shaped, magnetic shield and an electrical shielding. The magnetic shield has a passage opening along its main extension axis;
• c) sliding over the magnetic shield by moving the at least two conductors relative to the magnetic shield parallel to the main extension axes through the through-hole. The relative movement is in this case such that the at least two conductors extend in the passage opening and the magnetic shield surrounds the at least two conductors completely along a circumference of the cable; and
• d) applying the electrical shield so that the electrical shield surrounds the at least two conductors and the magnetic shield.

The electrical shield is also cylindrical, for example, and has a passage opening. Step d) then takes place analogously to step c).

For example, step c) is performed before step d). Alternatively, the electrical shielding may be applied to the magnetic shielding, for example, prior to step c).

• a) Bereitstellen wenigstens zweier Leiter, die mit ihren Haupterstreckungsachsen parallel, benachbart zueinander angeordnet und voneinander elektrisch isoliert ausgebildet sind;
• b‘) Bereitstellen einer zylindrisch geformten, magnetischen Schirmung sowie einer elektrischen Schirmung. Hierbei weist die magnetische Schirmung eine Durchgangsöffnung entlang ihrer Haupterstreckungsachse sowie einen Spalt in ihrer Mantelfläche entlang der Haupterstreckungsachse auf. Der Spalt erstreckt sich von der Mantelfläche hin zu der Durchgangsöffnung;
• c‘) Aufdrücken der magnetischen Schirmung, indem die wenigstens zwei Leiter relativ bezüglich der magnetischen Schirmung durch den Spalt senkrecht zu den Haupterstreckungsachsen bewegt werden. Die relative Bewegung erfolgt hierbei derart, dass die wenigstens zwei Leiter sich in der Durchgangsöffnung erstrecken und die magnetische Schirmung die wenigstens zwei Leiter zumindest teilweise entlang eines Umfangs des Kabels umgibt; und
• d) Aufbringen der elektrischen Schirmung, so dass die elektrische Schirmung die wenigstens zwei Leiter und die magnetische Schirmung umgibt.

According to a third aspect, the invention relates to a method for producing a cable according to the first aspect. The method comprises the steps:

• a) providing at least two conductors, which are arranged with their main extension axes parallel, adjacent to each other and electrically isolated from each other;
• b ') providing a cylindrically shaped magnetic shield and an electrical shielding. In this case, the magnetic shield has a passage opening along its main extension axis and a gap in its lateral surface along the main extension axis. The gap extends from the lateral surface towards the passage opening;
• c ') pressing the magnetic shield by moving the at least two conductors relative to the magnetic shield through the gap perpendicular to the major axes of extension. The relative movement is in this case such that the at least two conductors extend in the passage opening and the magnetic shield surrounds the at least two conductors at least partially along a circumference of the cable; and
• d) applying the electrical shield so that the electrical shield surrounds the at least two conductors and the magnetic shield.

The electrical shield is, for example, likewise cylindrical and has a passage opening and a gap in its lateral surface along the main extension axis. The step d) then takes place analogously to the step c ').

For example, step c ') is performed before step d). Alternatively, the electrical shielding may be applied to the magnetic shielding, for example, prior to step c ').

According to a fourth aspect, the invention relates to a power supply system for a vehicle. The power supply system comprises a cable according to the first aspect and an AC power source and a load.

The AC power source is coupled to the load by means of the at least two conductors of the cable such that a balance of a current flow through the cable substantially compensates.

The AC power source may in particular be arranged externally to the vehicle. The AC power source may be, for example, an inverter. The AC power source may also be disposed in the vehicle. The AC power source may then be, for example, an inverter or a coil for inductive energy transmission.

The consumer may in particular be arranged externally to the vehicle. The consumer may be, for example, a coil for inductive energy transfer. The consumer can also be arranged in the vehicle beyond. The consumer may then be, for example, a rectifier or an electric drive of the vehicle.

In an advantageous embodiment according to the fourth aspect, a current flow provided by the AC power source to the cable has a frequency in the range between 1 kHz and 200 kHz.

Embodiments of the invention are explained in more detail below with reference to the schematic drawings.

• 1 und 2 elektrische Energieversorgungssysteme für ein Fahrzeug,
• 3 und 4 stromdurchflossene Leiter,
• 5 und 6 elektrisch geschirmte Doppelleiter,
• 7 ein erstes Ausführungsbeispiel eines Kabels in Querschnittdarstellung,
• 8 ein Energieübertragungssystem gemäß 1 mit dem Kabel gemäß 7.
• 9 bis 11 das Kabel gemäß 7 in Detailansicht,
• 12 ein zweites Ausführungsbeispiel eines Kabels in Querschnittdarstellung,
• 13 ein elektrisch ungeschirmtes Kabel,
• 14 ein drittes Ausführungsbeispiel eines Kabels in Querschnittdarstellung,
• 15 und 16 Verfahren zur Herstellung des Kabels gemäß 7, 12 oder 14, und
• 17 und 18 ein viertes Ausführungsbeispiel eines Kabels in Querschnittdarstellung.

Show it:

• 1 and 2 electrical energy supply systems for a vehicle,
• 3 and 4 current-carrying conductors,
• 5 and 6 electrically shielded double conductors,
• 7 a first embodiment of a cable in cross-sectional view,
• 8th a power transmission system according to 1 with the cable according to 7 ,
• 9 to 11 the cable according to 7 in detail view,
• 12 A second embodiment of a cable in cross-sectional view,
• 13 an electrically unshielded cable,
• 14 A third embodiment of a cable in cross-sectional view,
• 15 and 16 Method for producing the cable according to 7 . 12 or 14 , and
• 17 and 18 A fourth embodiment of a cable in cross-sectional view.

Elements of the same construction or function are provided across the figures with the same reference numerals.

Electrical cables can be used in some applications to carry high currents at high frequencies. Typically cables are used for inductive charging of a vehicle or electric drive systems as connecting lines.

1 shows a first electric power supply system for a vehicle. The first electric power supply system includes an inverter 110 as an AC source, a cable 101 (RF line) and a arranged on the ground primary coil 100 as an electrical consumer. In addition, shows 1 a second electric power supply system for the vehicle, which is a secondary coil integrated into an underbody of the vehicle 200 as an AC source, a cable 201 (RF line) and a rectifier 210 as a consumer. The primary coil 100 is here with the secondary coil 200 can be coupled to the wireless power transmission and forms an inductive charging system. The rectifier 210 is by means of another line 203 to an electrical energy storage 220 coupled.

2 shows a third electric power supply system for a vehicle, which in turn is an inverter 230 as an AC source, a cable 207 (three-phase (RF) line) and an electric motor 240 , in particular a drive motor of the vehicle, as an electrical consumer comprises. Here is the inverter 230 by way of example with the electrical energy storage 220 according to 1 by means of another line 205 coupled.

For example, when using the cable 101 . 201 and 207 Amperages by about 50 A at frequencies in the range of about 85 kHz (or 1 kHz for the cable 207 ) occur. In many cases, high voltages up to a few thousand volts can occur at the same time. By way of example, in the case of inductive charging this is due to resonant circuits and corresponding resonance peaks.

Due to the aforementioned high frequencies and currents, relatively high magnetic fields can form around the conductors of the cables. 3 shows one with electricity I in the direction of the drawing plane current-carrying first conductor 3 and thereby caused magnetic field lines 21 , 4 shows the current flowing through the first ladder 3 with thereby caused magnetic field lines 23 and a second conductor arranged parallel thereto 5 , which is opposite current flowing through, thereby causing magnetic field lines 25 ,

At a current of 50 A and a diameter of the conductor 3 . 5 together with insulation of 12 mm (6 mm wire, 6 mm insulation, for example) results in a surface area of the respective insulation with a flux density of approx. 1.66mT.

For electromagnetic shielding, for example, braided shields can be used, which consist of electrically conductive material. By way of example, this may be a wire mesh made of aluminum, in particular in the case of use of the cable in vehicles. In the following, the electrically conductive braided shield is also referred to as electrical shielding. This has a magnetic conductivity in about the free space, the air or insulation materials ( μ _r ~ 1).

5 shows a line with the two conductors 3 . 5 according to 4 and such an electrical shield 8th , Moreover, the magnetic field lines are dashed 23 . 25 in its propagation form without the electrical shielding 8th according to 4 shown. The magnetic field lines 23 . 25 that the electrical shielding 8th Crossing leads to a voltage and current induction in the electrical shield 8. The more field lines 23 . 25 the electrical shielding 8th Cross, the higher is an induction voltage and thus in the electrical shielding 8th induced current. 5 schematically shows a vertically extending from the plane, induced current 31 in the electrical shield 8th and an induced current running counter to the plane of the drawing 33 in the electrical shield 8th ,

The voltage and current induction causes an opposite magnetic field is generated which magnetic field lines outside the electric screen 8th extinguishes. 6 shows in this context the two conductors 3 . 5 with the electrical shielding 8th according to 5 with resulting magnetic field lines 27 . 29 , The respective associated stream 31 . 33 in the electrical shield 8th compensates the field lines 23 . 25 which due to low magnetic conductivity of the electric screen 8th thwart this. A current of the current 31 . 33 in the electrical shield 8th can have a high percentage of electricity in the conductors 3 . 5 For example, be about 10%. This can lead to high losses in the electrical shielding 8th and lead to a thermal overload of such a cable.

The electrical shielding 8th shields the alternating magnetic fields 23 . 25 this only indirectly from the currents 31 . 33 in the electrical shield 8th be induced. DC fields are created by the electrical shielding 8th however, not shielded. Alternating fields with low alternating frequency - if a penetration depth of the corresponding field in the electrical shielding 8th higher than a thickness of the electrical shielding 8th is - only partially shielded.

To overcome these problems can be exemplified a large distance between the electrical shielding 8th and the two ladders 3 . 5 and / or a particularly high thickness of the electrical shielding can be selected. However, this leads to high diameters and a high weight of the line and impairs a bendability or layability of the line.

In the following, therefore, a cable is proposed which helps to keep losses low and ensures mechanical flexibility.

7 shows in a first embodiment a cross section through a cable 1 , which can be used as an AC line (RF line), for example. The cable 1 has a first ladder 3 , for example, a Hinleiter, with insulation 4 , a second conductor 5 , For example, a return conductor, with insulation 6 and a common outer sheath with shielding function. The outer sheath comprises, in particular, a magnetic shield 7, which is characterized by magnetic conductivity and mechanical flexibility. The outer jacket may further comprise an electrical shield 8th have (see. 14 ). Between the isolation 4 . 6 the single conductor 3 . 5 and the outer shell may, for example, a filling material 9 be introduced, which serves as a strain relief. For reasons of clarity, in the following figures, only the magnetic shielding 7 represented the outer shell.

8th shows an exemplary use of the cable 1 according to 7 as a cable 101 in the first energy transmission system according to 1 , The primary coil 100 includes a coil 103 and a housing 105 , The ladder 3 . 5 of the cable 1 are each with a plug 107 to the coil 103 as well as with a plug 109 to electronics for controlling the coil 103 , in the present example, the inverter 110 coupled. The conductors are from the magnetic shielding 7 surround. In operation of the power transmission system is the sink 103 and the cable 101 with alternating current flows through. The inductive charging application typically uses a frequency of 85kHz. The currents can be very high. In the case of inductive charging, 50A can be taken as the typical value.

At the same time, the currents in the two conductors are the same 3 and 5 out. An amperage of the current through the return conductor 5 in the direction of the inverter 110 back is thus equal in magnitude equal to a current strength of the current through the forward conductor 3 in the direction of the coil 103 ,

Based on 9 and 10 again is the cross-section of the cable 1 according to 7 shown. 9 also shows magnetic field lines 41 around the leader 3 , magnetic field lines 43 around the return conductor 5 as well as magnetic field lines 45 inside the cable 1 between the two ladders 3 . 5 through the isolation 4 . 6 , In 10 are corresponding to this dimensions of the cable 1 shown. This is with b _screen a (mean) thickness of the magnetic shield 7 as well as with b _Iso one (average thickness of the respective insulation 4 . 6 designated. Further referred to c _screen a (mean) length of field flux through the magnetic shield 7 , while c _Iso a (mean) length of field flux through the insulation 4 . 6 designated. Finally, there is an axis of symmetry x of the cross section between the two conductors 3 . 5 shown. For one half of the cable 1 (to the right of the symmetry axis x) 11 an equivalent circuit diagram. The magnetic voltage V _m is proportional to the current I through the respective conductor 3 . 5 , The equivalent circuit diagram shows the magnetic flux Φ and the magnetic resistances of the magnetic shield 7 , R _{m, screen} and the respective insulation 4 . 6 . Rm _{, iso} ,

The magnetic voltage drops at the magnetic resistors R _{m, screen} and Rm _{, iso} behave proportionally to these. For a magnetic resistance R _m , in general, R _m = 1 / (μ * A), with the length l of a magnetic conductor or the field lines and its cross-sectional area A , Because the cross-sectional area A of the magnetic conductor, ie the cross section of the jacket (thickness times length) is approximately proportional to the thickness b _screen the magnetic shielding 7 is can be approximately assumed that Rm _{, iso} ~ C _iso / (μ ₀ * l * b _iso ) and R _{m, screen} ~ c _screen / (μ ₀ * μ _r * l * b _shield ), where l is a length of the respective conductor 3 . 5 designated.

It follows that the magnetic field strength along the length c _screen according to the resistance ratios R _{m, screen closed} Rm _{, iso} divides, namely: $${\text{R}}_{\text{m}\text{Iso}}{\text{/}}_{\text{rm}\text{,Umbrella}}~{\mathrm{\mu }}_{\text{r}}*{\text{b}}_{\text{umbrella}}*{\text{c}}_{\text{iso}}\text{/}\left({\text{c}}_{\text{umbrella}}*{\text{b}}_{\text{iso}}\right)>>1$$

The largest proportion of magnetic resistance is therefore inside the cable 1 between both individual leaders 3 . 5 , Thus, the largest magnetic field strength occurs inside the cable between the two individual conductors 3 . 5 on. Outside the magnetic shield 7 the magnetic field strength H is significantly reduced. The magnetic shielding 7 reduces the magnetic field strength H outside. With double thickness b _screen of magnetic screen or double μ _r halves the outer field (double attenuation).

With the simplistic assumption of a circular magnetic field around a conductor of radius r, a magnetic flux density B _normal to an outside of a cable without magnetic shielding ( μ _r = 1): $${\text{B}}_{\text{normal}}={\mathrm{\mu }}_0\text{* I /}\left(2*\mathrm{\pi }\text{* r}\right)$$

$$\begin{array}{cc}{\text{R}}_{\text{m}\text{,Schirm}}& \sim {\text{c}}_{\text{Schirm}}\text{/}\left({\mathrm{\mu }}_0*{\mathrm{\mu }}_{\text{r}}*\text{l}*{\text{b}}_{\text{Schirm}}\right)\\ & \sim 3*\mathrm{\pi }\text{*r}\mathrm{/}\left(2*{\mathrm{\mu }}_0*{\mathrm{\mu }}_{\text{r}}*\text{l}*{\text{b}}_{\text{Schirm}}\right)\end{array}$$

With the further simplifying assumption that a distance through an insulation of the conductor corresponds to a quarter of the circumference and a distance through the magnetic shield corresponds to three quarters of the circumference, the following applies: $$\begin{array}{cc}{\text{R}}_{\text{m}\text{Iso}}& ~{\text{c}}_{\text{iso}}\text{/}\left({\mathrm{\mu }}_0*\text{l}*{\text{b}}_{\text{iso}}\right)\\ & ~\mathrm{\pi }\text{* r}\mathrm{/}\left(2*{\mathrm{\mu }}_0*\text{l}*{\text{b}}_{\text{iso}}\right)\text{and}\end{array}$$

$$\begin{array}{cc}{\text{R}}_{\text{m}\text{,Umbrella}}& ~{\text{c}}_{\text{umbrella}}\text{/}\left({\mathrm{\mu }}_0*{\mathrm{\mu }}_{\text{r}}*\text{l}*{\text{b}}_{\text{umbrella}}\right)\\ & ~3*\mathrm{\pi }\text{* r}\mathrm{/}\left(2*{\mathrm{\mu }}_0*{\mathrm{\mu }}_{\text{r}}*\text{l}*{\text{b}}_{\text{umbrella}}\right)\end{array}$$

The magnetic flux through the screen is so $$\text{I /}\left({\text{R}}_{\text{m}\text{Iso}}+{\text{R}}_{\text{m}\text{,Umbrella}}\right)=\text{I}*2*{\mathrm{\mu }}_0*\text{l}*\text{/}\left(\mathrm{\pi }*\text{r}*\left(\left({\text{1 / b}}_{\text{iso}}\right)+\left(3\text{/}{\mathrm{\mu }}_{\text{r}}*{\text{b}}_{\text{umbrella}}\right)\right)\right)$$

This results in magnetic flux density along the field lines 45 (see. 9 ) in the magnetic shield 7 as a magnetic flux divided by an area l * b _screen : $$\begin{array}{cc}{\text{B}}_{\text{umbrella}}& =\text{I}*2*{\mathrm{\mu }}_0*\text{l}*\text{/}\left(\mathrm{\pi }*\text{r}*\left(\left({\text{1 / b}}_{\text{iso}}\right)+\left(3\text{/}{\mathrm{\mu }}_{\text{r}}*{\text{b}}_{\text{umbrella}}\right)\right)*{\text{l * b}}_{\text{umbrella}}\right)\\ & =\text{I}*2*{\mathrm{\mu }}_0\text{/}\left(\mathrm{\pi }*\text{r}*\left(\left({\text{1 / b}}_{\text{iso}}\right)+(3\text{/}{\mathrm{\mu }}_{\text{r}}*{\text{b}}_{\text{umbrella}}{}_{\text{)}}\right)*{\text{b}}_{\text{umbrella}}\right)\\ & =\text{I}*2*{\mathrm{\mu }}_0\text{/}\left(\mathrm{\pi }*\text{r}\left({\text{b}}_{\text{umbrella}}{\text{/ b}}_{\text{iso}}+3\text{/}{\mathrm{\mu }}_{\text{r}}\right)\right)\\ & =4*\left(\text{I}*2*{\mathrm{\mu }}_0\text{/}\left(2*\mathrm{\pi }*\text{r}\right)\right)\text{/}\left({\text{b}}_{\text{umbrella}}{\text{/ b}}_{\text{iso}}+3\text{/}{\mathrm{\mu }}_{\text{r}}\right)\\ & =4*{\text{B}}_{\text{normal}}\text{/}\left({\text{b}}_{\text{umbrella}}{\text{/ b}}_{\text{iso}}+3\text{/}{\mathrm{\mu }}_{\text{r}}\right)\end{array}$$

Due to the continuity relationship of the field strength H at the outer edge of the magnetic shield 7 follows that the B field outside by the factor μ _r smaller than inside the magnetic shield 7 : $${\text{H}}_{\text{umbrella}}=4*{\text{H}}_{\text{normal}}\text{/}\left({\mathrm{\mu }}_{\text{r}}*{\text{b}}_{\text{umbrella}}{\text{/ b}}_{\text{iso}}+3\right)$$

$${\mathrm{\mu }}_{\text{r}}*\text{b+3}=\mathrm{40,}\text{ mit dem Dickenverhältnis b}={\text{b}}_{\text{Schirm}}{\text{/b}}_{\text{Iso}}$$

$${\mathrm{\mu }}_{\text{r}}*\text{b}\mathrm{=}\text{37}$$

Consequently, the shielding effect increases with thickness b _screen the magnetic shielding 7 and the relative permeability μ _r the magnetic shielding 7 to. A reduction of the magnetic field by the magnetic shielding 7 should be bigger a factor 5 be. An example becomes a desired factor 10 accepted. From the previous equation, therefore, arise for the thickness b _screen the magnetic shielding 7 , the relative permeability μ _r the magnetic shielding 7 and the thickness of the respective insulation 3 . 5 : $$\begin{array}{c}1=4*10/\left({\mathrm{\mu }}_{\text{r}}*{\text{b}}_{\text{umbrella}}{\text{/ b}}_{\text{iso}}+3\right)\\ =40\text{/}\left({\mathrm{\mu }}_{\text{r}}*\text{b}\mathrm{+}\text{3}\right)\end{array}$$

$${\mathrm{\mu }}_{\text{r}}*\text{b + 3}=40\text{with the thickness ratio b}={\text{b}}_{\text{umbrella}}{\text{/ b}}_{\text{iso}}$$

$${\mathrm{\mu }}_{\text{r}}*\text{b}\mathrm{=}\text{37}$$

As a possible solution comes μ _r = 10 and b = 3.7 into consideration; the magnetic shielding 7 thus has approximately 3 times the thickness of the insulation 3 . 5 on.

12 shows a second embodiment of the cable 1 , The cable 1 differs from the first exemplary embodiment by a shape of the magnetic shield 7 , As in the overview figure left in 12 as well as the magnification right in 12 shown has the magnetic shield 7 each one gap along the axis of symmetry x (see. 10 ), for example, with the filler 9 filled or free. This has the advantage of having the effective length c _Iso is increased, so that the magnetic resistance Rm _{, iso} and the magnetic flux decreases. In particular, as compared with the first embodiment, a lower magnetic flux in the magnetic shield 7 achieved so that it can be thinner on average thinner. In addition, an inductive line lining (electrical model of the line) can be reduced. The magnetic field lines hardly emerge from the unshielded gap, since they are closed in the interior to the opposite side.

The gap may be towards an exterior of the cable 1 rejuvenate. Advantageously, this further increases the effective length c _Iso .

Alternatively or additionally, the magnetic shield 7 be formed such that the thickness b _screen the magnetic shielding 7 varies along its circumference (not shown).

Alternatively or additionally, the magnetic shield 7 Furthermore, be designed such that the relative permeability μ _r the magnetic shielding 7 varies along its circumference (not shown).

Even through these measures, the effective length can be c _Iso be enlarged and it adjusts the aforementioned advantages.

Based on 13 is a cable according to the previous embodiments with magnetic shielding 7 , but without electrical shielding 8th shown. Frequently occur as in the 1 and 2 described applications for the transmission of high power and high voltages. Accompanying electric fields or field lines 51 occur in addition to the magnetic fields (not shown here) and are not reduced by the magnetic shield 7. Therefore, in many cases, an additional screen is necessary.

14 shows a third embodiment of the cable 1 with the electrical shielding 8th , Electric field lines 53 stay inside the electrical shield 8th because the field strength is shorted to the metallic one. In other words, the electric field lines go from the potential of the positive line to the potential of the negative line. In this case, they spread in space without the electrical shield, which would serve as an electrical conductor, so that a density of the electric field lines at short distances is higher than with long field lines. The electrical shielding as an electrical conductor is a short circuit for the electric field lines (E-field). As in 14 Shown, these field lines end and begin at the electrical shielding. Since the electrical shielding for the electric field represents a short circuit, a common potential arises in the electrical shield, which lies in the middle of the voltages of the positive and the negative conduction. Outside the electrical shield, no E-field can occur, since there is no potential difference anymore. The electrical shielding 8th For example, in a protective jacket 10 of the cable 1 be embedded.

As with the basis 1 and 2 described applications are the frequencies occurring <1 MHz and the dimensions of the cable 1 are small compared to the wavelength (at 1 MHz this is 300m), prevail near field conditions. Consequently, electric and magnetic fields can be considered independently.

In an arrangement of the electrical shielding 8th around the magnetic shielding 7 are outside the magnetic shield 7 only electric fields available. Therefore, by the electrical shielding 8th only electric fields shielded. This requires only minimal shielding currents to increase the capacitance between the conductors 3 . 5 and the electrical shielding 8th tranship.

Based on 15 and 16 are two methods of making the cable 1 shown. An unshielded cable is provided in each case. As an example, the two conductors insulated from each other are used 3 . 5 provided. As shown, the ladder 3 . 5 already with the filling material 9 be enveloped. In the filler 9 this may be, in particular, a magnetically neutral shell.

In a first embodiment (first method) is a slotted magnetic shield 7a provided. With the magnetic shielding 7a it is the magnetic shielding 7 of the previous embodiments, which is cylindrically shaped, a passage opening along its main extension axis and a gap in its lateral surface along the main extension axis has (see. 12 ). In an assembly step A becomes the magnetic shielding 7a laterally over the ladder 3 . 5 pressed so that the magnetically shielded cable 1 arises ( 16 ). The magnetic shielding 7a is particularly elastic in this context.

In a second embodiment (second method) is a magnetic shield 7b provided, in contrast to the magnetic shielding 7a only has a passage opening along its main extension axis. In an assembly step B becomes the magnetic shielding 7b over the ladder 3 . 5 pushed so that the magnetically shielded cable 1 arises ( 16 ).

In both methods, the electrical shielding can be retrofitted 8th be applied. Alternatively, this can for example already with the magnetic shield 7a or 7b in the assembly steps A or B be applied.

In a fourth embodiment, the cable is different 1 in the number of conductors (cf. 17 and 18 ). 17 shows the primary coil 100 according to 1 in plan view. The sink 103 is coupled due to high amperage by means of several parallel lines which together in the cable 1 bundled and form a multi-phase conductor system. By way of example, the coil has 103 a plurality of individual coils, which are each coupled to one of the parallel lines.

18 shows the cable 1 as a four-ladder system, where next to the two ladders 3 . 5 two additional conductors 2a . 2 B from the magnetic shield 7 are surrounded.

LIST OF REFERENCE NUMBERS

1

electric wire

2a, 2b

more leaders

3

first leader

4

isolation

5

second conductor

6

isolation

7, 7a, 7b

magn. shielding

8th

el. Shielding

9

filling compound

10

mantle

21

magnetic field

23

magnetic field

25

magnetic field

27

magnetic field

29

magnetic field

31

shield current

33

shield current

41

magn. field lines

43

magn. field lines

45

magn. field lines

51

el. field lines

53

el. field lines

100

primary coil

101

RF line

103

Kitchen sink

105

casing

107

plug

109

plug

110

inverter

200

secondary coil

201

RF line

203

management

205

management

207

RF lines

210

rectifier

220

Storage

230

inverter

240

electric motor

c _screen

Screen flow length

c _Iso

Isolation flow length

b _screen

screen thickness

b _Iso

insulation thickness

Rm _{, iso}

magn. insulation resistance

R _{m, screen}

magn. shield resistance

vm

magn. tension

I

Electricity

Φ

magn. River

μ _r

relative magn. permeability

A

assembly step

B

assembly step

Claims (14)

Cable (1) comprising at least two conductors (3, 5), a magnetic shield (7) and an electrical shield (8), wherein - The at least two conductors (3, 5) are arranged with their main extension axes parallel, adjacent to each other and electrically isolated from each other, - The magnetic shield (7) which surrounds at least two conductors (3, 5) at least partially along a circumference of the cable (1), and - The electrical shield (8) surrounding at least two conductors (3, 5) and the magnetic shield (7). Cable (1) to Claim 1 , wherein the at least two conductors (3, 5) have a diameter d> 1 mm. Cable (1) according to one of the preceding Claims 1 or 2 , wherein the magnetic shield (7) has a relative magnetic permeability μ _r > 2. Cable (1) according to one of the preceding Claims 1 to 3 wherein the at least two conductors (3, 5) have an insulation (4, 6) with a thickness b _Iso , the magnetic shield (7) has a thickness b _screen and a relative magnetic permeability μ _r , and for the thickness b _Iso the insulation (4, 6), the thickness b _{screen of} the magnetic shield (7) and the relative magnetic permeability μ _{r of} the magnetic shield (7): $${\mathrm{\mu }}_{\text{r}}*{\text{b}}_{\text{umbrella}}{\text{/ b}}_{\text{iso}}>\mathrm{17th}$$

Cable (1) according to one of the preceding Claims 1 to 4 wherein a thickness b _{screen of} the magnetic shield (7) and / or a relative magnetic permeability μ _{r of} the magnetic shield (7) varies along a circumference of the cable (1). Cable (1) according to one of the preceding Claims 1 to 5 wherein the magnetic shield (7) has a recess which is disposed in an area between the main extension axes of the at least two conductors (3, 5) and which tapers toward an exterior of the cable (1). Cable (1) according to one of the preceding Claims 1 to 6 in that the electrical shield (8) is embedded in a jacket of the cable (1), which encloses the at least two conductors (3, 5) and the magnetic shield (7). Cable (1) according to one of the preceding Claims 1 to 7 in that the magnetic shield (7) completely surrounds the at least two conductors (3, 5) along the circumference of the cable (1). Cable (1) according to one of the preceding Claims 1 to 8th in which the magnetic shield (7) is designed to be electrically insulating. Cable (1) according to one of the preceding Claims 1 to 9 in which the magnetic shield (7) comprises or consists of a polymer, wherein ferrite powder is introduced into the polymer. Method for producing a cable (1) according to one of the preceding Claims 1 to 10 comprising the steps of: providing at least two conductors (3, 5) parallel with their main axes of extension adjacent to each other and electrically isolated from each other, providing a cylindrically shaped magnetic shield (7) and an electrical shield (8) wherein the magnetic shield (7) has a passage opening along its main axis of extension, sliding the magnetic shield (7) by moving the at least two conductors (3, 5) through the passage opening relative to the magnetic shield (7) parallel to the principal axes of extension such that the at least two conductors (3, 5) extend in the through hole and the magnetic shield (7) completely surrounds the at least two conductors (3, 5) along a circumference of the cable (1), and - applying the electrical shield (8), so that the electrical shield (8) the at least two conductors (3, 5) and the magnetic Surrounds shield (7). Method for producing a cable (1) according to one of the preceding Claims 1 to 10 comprising the steps of: providing at least two conductors (3, 5) parallel with their main axes of extension adjacent to each other and electrically isolated from each other, providing a cylindrically shaped magnetic shield (7) and an electrical shield (8) wherein the magnetic shield (7) has a passage opening along its main axis of extension and a gap in its lateral surface along the main axis of extension, and the gap extends from the lateral surface to the passage opening, pressing the magnetic shield (7) by the at least two Conductors (3, 5) are moved relative to the magnetic shield (7) through the gap perpendicular to the main axes of extension so that the at least two conductors (3, 5) extend in the through hole and the magnetic shield (7) extends the at least two Ladder (3, 5) at least partially along a circumference of the cable (1), and - applying the electrical shield (8) so that the electrical shield (8) surrounds the at least two conductors (3, 5) and the magnetic shield (7). A power supply system for a vehicle, comprising - a cable (1) according to any one of the preceding Claims 1 to 10 - an AC power source (110), and - a load (100), wherein the AC power source (110) is coupled to the load (100) by means of the at least two conductors (3, 5) of the cable (1) such that a Balance of a current flow through the cable (1) substantially compensates. Energy supply system according to Claim 13 wherein a current flow provided by the AC power source to the cable (1) has a frequency in the range between 1 kHz and 200 kHz.

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