EP2651688A1

EP2651688A1 - Device for the inductive transmission of electrical energy

Info

Publication number: EP2651688A1
Application number: EP11782596.8A
Authority: EP
Inventors: Mathias Wechlin; Pascal Asselin
Original assignee: Conductix Wampfler GmbH
Current assignee: Conductix Wampfler GmbH
Priority date: 2010-12-16
Filing date: 2011-11-09
Publication date: 2013-10-23
Also published as: US20140292091A1; CN103260938A; DE102010054848A1; US9473211B2; WO2012079861A1

Abstract

In a device for the inductive transmission of electrical energy having a coil (2) which can be inductively coupled to another coil by suitable positioning of the two coils relative to one another in order to transmit energy, having a power electronic unit for drawing electrical power from the coil (2) or for outputting electrical power into the coil (2) and having a feedline which connects the coil (2) to the power electronic unit, the feedline is composed of at least two multi-conductor cables (4, 5) with conductors (4A-4D; 5A-5D) which are insulated from one another and the connection of each terminal (2A, 2B) of the coil (2) to a respectively assigned terminal of the power electronic unit is composed of plurality of conductors (4A-4D; 5A-5D) of the multi-conductor cables (4, 5). Each terminal (2A, 2B) of the coil (2) is preferably connected to the respectively assigned terminal of the power electronic unit by conductors (5A, 5C, 4B, 4D; 4A, 4C, 5B, 5D) of at least two different cables (4, 5) and the same number of conductors of each individual cable (4, 5) connect each terminal (2A, 2B) of the coil (2) to the respectively assigned terminal of the power electronic unit.

Description

Device for inductive transmission of electrical energy

The invention relates to a device for inductive transmission of electrical energy according to the preamble of claim 1.

For inductive charging of electric vehicles, the vehicle-side secondary coil is preferably arranged on the underside of the vehicle, so that the inductive coupling with the primary coil of a charging station can be made by simply stopping the vehicle at the charging station under appropriate orientation of the secondary coil to a arranged on the ground primary coil. In this case, the smallest possible height of the secondary coil is desired because for their attachment to the underside of the vehicle usually only a mounting space of low height is available. The secondary coil must be connected by a supply line to a vehicle-side power electronic unit, which converts the signal coming from the secondary coil into a form suitable for charging the vehicle battery. The supply line must also be at least partially laid on the underside of the vehicle and is therefore subject to the same height requirements as the secondary coil.

The space available for housing additional components such as an inductive transmission device in a vehicle is generally narrow. Therefore, a low overall height of the secondary coil and its supply line in a location other than the bottom, such as in the area of a bumper or a crumple zone, of interest.

Because of the relatively high operating frequency of the inductive transmission link, which is usually today in the order of 20 kHz and could shift further up in the future, must be taken into account in the design of the lead of the skin effect, which makes special demands on the supply cable. One possible solution is the use of high-frequency stranded cable, which consists of a large number of very thin individual wires insulated from each other by a layer of varnish. However, this type of cable is relatively expensive and especially in shielded design Connecting its ends to other components, ie here to the secondary coil and the power electronic unit, difficult to process.

When using a normal cable, because of the large current and the skin effect, a large wire cross section must be selected, which results in a correspondingly large overall cross section of the cable. Therefore, the demand for a supply line of low height, in particular a height which is not greater than that of the secondary coil, hardly meet with a normal cable. A low height is desirable in a device for inductive charging of an electric vehicle for the primary coil and its supply to the charging station, especially if the primary coil and its supply not sunk in the ground, but mounted on the surface of a Fahrzeugabstellplatzes lying and thus potential pitfalls for Represent vehicle occupants, or if the primary coil should be designed as a portable unit.

From US 2001/0002773 AI a supply cable with a plurality of insulated wires for the primary coil of a device for inductively charging the battery of an electric vehicle is known. The wires are insulated from each other to guide the primary current in both directions between a charging station and a portable primary coil within a single cable of circular overall cross-section so that only a single cable is needed to connect the charging station to the primary coil.

The US 6,649,842 Bl shows the connection of a socket with an electrical energy source by two multi-core cable, the wires are connected at the ends without soldering to the power source or the socket. Further, this document teaches the use of ferrite cores to balance the currents between the wires of a multi-core cable. For this purpose, the individual wires are combined in several stages into groups of increasing size and in each stage in groups led together by ferrite cores.

No. 6,506,971 B1 shows a multi-core electrical cable in which at least one core consists of a plurality of mutually insulated and mutually parallel partial cores and each sub-artery adjacent to a core or sub-artery, which is a phase shift or current flowing in the opposite direction, so that the magnetic field outside the cable, which is caused by the currents flowing in the cable as a whole, has the lowest possible field strength. The invention has for its object to provide a simple and cost-effective solution in a device for inductive transmission of electrical energy for the realization of a low-height connection between the coil and a power electronic unit. This object is achieved by a device having the features of claim 1. Advantageous embodiments of the invention are specified in the subclaims.

According to the invention consists in a generic device for inductive transmission of electrical energy, the supply line between the coil and the power electronic unit of at least two multi-core cables with insulated wires and the

Connection of each terminal of the coil with a respective associated terminal of the power electronic unit consists of a plurality of wires of the multi-core cable.

This makes it possible to use cables with a small overall cross-section and to comply in this way a total low height of the supply line. The cable cross section which is too small for the current to be conducted is compensated by the fact that the

Electricity is distributed to several wires.

Preferably, each terminal of the coil is connected to the respective associated terminal of the power electronic unit by cores of at least two different cables. As a result, flows in each cable currents from opposite direction, the magnetic fields are thus directed against each other and therefore at least partially compensate each other. This is with regard to the avoidance of disturbances of electronic vehicle components by the outgoing from the lead magnetic alternating field of relatively high field strength and frequency of advantage. For the compensation effect, it is particularly favorable if the same number of wires of each individual cable connect each of the two terminals of the coil to the respectively assigned connection of the power electronic unit. It is even more favorable for the compensation of the magnetic field if, in addition, the cores are arranged symmetrically in the cross-section of each cable and assigned to the terminals of the coil so that cores with the same current direction are always arranged in pairs symmetrically to the center of a cable and in the circumferential direction on each alternate through the center of the cable and the centers of two mutually symmetrical wires defined circle cores with each other opposite current direction. In this case, the magnetic fields of the individual wires of each cable outside the cable compensate for each other even at a small distance from the cable largely, provided that the amounts of the partial currents of all wires are the same.

Furthermore, it is advantageous if all the wires of the cable, which connect a terminal of the coil to the same terminal of the power electronic unit, for uniform distribution of the total current to the individual wires cyclically in pairs with each opposite direction of current through closed magnetic cores are performed. A uniform distribution of the total current to the individual wires is desirable, both with regard to the compensation of the magnetic field emanating from the supply line, and in the interest of a low ohmic total resistance of the supply line and avoidance of uneven power loss and thus heating of the various wires.

A reasonable guideline for the total cross-section of each of the multicore cables is the height of the coil, which should not be exceeded, so that the supply line a space of the same height is sufficient as the coil occupies. Further details and advantages of the invention are disclosed in the following description of an embodiment with reference to the drawings. In these shows

1 schematic representations of a vehicle equipped with a device according to the invention vehicle in the view from below and in a partial longitudinal section,

2 shows a configuration according to the invention of two four-wire cables in cross-section,

Fig. 3 shows an example of a connection according to the invention of a secondary coil to two four-core cable and Fig. 4 shows an arrangement for symmetrical current distribution on four wires of a cable.

As shown schematically in FIG. 1, a device for the inductive absorption of electrical energy with a secondary coil 2 and a power electronic unit 3 is arranged on the underside of a vehicle 1, which are interconnected by a two-pole supply line 4, 5. The power electronic unit 3 is connected to a battery, not shown, from which an electric drive of the vehicle 1 is fed. The device is used to charge the vehicle battery at a charging station, which has a primary coil corresponding to the secondary coil 2. For charging the vehicle battery, the vehicle 1 is parked at the charging station, that the secondary coil 2 is aligned with the arranged on the ground primary coil and the two coils form a transformer, can be transmitted to the vehicle 1 via the electrical energy. 1, the secondary coil 2 is very flat, since only an installation space 6 of low height is available for this at the bottom of the vehicle 1. The same small height also has the channel 7, which leads from the installation space 6 to the power electronic unit 3 and is available for laying the supply line 4, 5 available. The supply line 4, 5 may therefore not have a larger cross-section than the overall height of the secondary coil 2, so that it does not protrude from the channel 7 down.

As shown in Fig. 2 right, the supply line 4, 5 according to the invention, for example, two cables 4 and 5, the respective total cross-section of the height h of the channel 7 corresponds. Each of the cables 4 and 5 has four equal insulated wires 4A to 4D and 5A to 5D, respectively, so that the current can be distributed to four wires in each direction. Each of the cables 4 and 5 has a diameter of the total cross-section including the outer jacket 4M and 5M, which corresponds to the height h of the channel 7, so that when connecting the secondary coil 2 with the power electronic unit 3 through the cables 4 and 5 the available height h is strictly adhered to.

Although compliance with the available height h is already achievable in that the four wires of the one cable 4 connect one terminal of the secondary coil 2 to one terminal of the power electronic unit 3 and the four wires of the other cable 5 the connect other terminal of the secondary coil 2 to the other terminal of the power electronic unit 3, it is appropriate to use for the connection of a terminal of the secondary coil 2 with a terminal of the power electronic unit 3 wires of different cables, as shown in Fig. 3. There, two wires 4B and 4D of the cable 4 and two wires 5A and 5C of the cable 5 are connected to one terminal 2A of the secondary coil 2, while the two other wires 4A and 4C of the cable 4 and the two other wires 5B and 5D of the cable 5 are connected to the other terminal 2B of the secondary coil 2. The connection to the two terminals of the power electronic unit 3 is made analogously thereto.

In this way, the total current of the circuit between the secondary coil 2 and the power electronic unit 3 in each of the two directions divided in half on the two cables 4 and 5, so that in total in each cable 4 and 5 two oppositely directed and the amount flow to equal currents. As a result, the magnetic fields caused by the currents outside the cables 4 and 5 approximately compensate each other and the electromagnetic compatibility of the inductive power receiving device with the electronic components of the vehicle 1 is improved. As shown in Fig. 2, the mutual compensation of the magnetic fields can be further improved by the fact that in a radially symmetrical arrangement of the wires 4A to 4D and 5A to 5 D within the cable 4 and 5, the assignment of the wires is chosen so that, for example, in the Cable 4, the wires 4A and 4C, which carry a current in one direction, are symmetrical to the center of the cable cross-section, and the wires 4B and 4D, which carry a current in the opposite direction, also symmetrically to the center of the cable cross-section a circle of the same radius. This ensures a substantial compensation of the magnetic fields already at a small distance from the cable 4, when the partial currents of all wires are the same amount. According to the same scheme, the assignment of the wires 5A to 5D is also selected for the cable 5.

In order to ensure the equality of the amounts of all of the individual wires 4A to 4D or 5A to 5D sub-streams, the wires connecting a terminal of the secondary coil 2 to the same terminal of the power electronic unit 3, cyclically in pairs, each with opposite current direction through closed magnetic cores out, as shown schematically in Fig. 4 by means of the connected to the terminal 2B of the secondary coil 2 wires 4A, 4C, 5B and 5D. Thus, the wires 5D and 4A are passed through the magnetic core 8, the wires 4A and 4C through the magnetic core 9, the wires 4C and 5B through the magnetic core 10 and the wires 5B and 5D through the magnetic core 11. As magnetic cores 8 to 11 ring cores made of ferrite can be used.

The current directions are indicated in Fig. 4 by in each case by arrows in the wires. For example, the wires 5D and 4A in the passage through the magnetic core 8 partial currents of opposite direction, although their current direction with respect to the connection of the secondary coil 2 with the power electronic unit 3 is the same. This is effected by the recognizable in Fig. 4 loop-shaped laying of the wire 5 D by the magnetic core 8. While the magnetic fields of the closely spaced in the passage through the magnetic core 8 cores 5D and 4A at the same amounts of their partial currents approximately compensate, different amounts of their partial currents an alternating magnetic field in the magnetic core 8 result. As a result, currents are induced in the wires 5D and 4A according to the Lenz 'rule, which counteract the change in the magnetic flux, ie the alternating magnetic field in the magnetic core 8. Consequently, the amounts of the partial currents in cores 5D and 4A are approximated.

According to the same principle, the partial currents in the wires 4A and 4C, in the wires 4C and 5B and in the wires 5B and 5D are paired with each other in pairs due to the arrangement of FIG. Due to the overall cyclic arrangement, there is also an overall convergence of all partial flows, so that the total current is distributed uniformly over the four cores 4A, 4C, 5B and 5D. This type of equalization of the partial currents is also provided in the wires 5A, 5C, 4B and 4D of the other current direction. A uniform distribution of the partial currents is of interest both with regard to the compensation of the magnetic fields and with regard to the current load of the individual wires. Previously, the application of the invention to the secondary side of a device for the inductive transmission of electrical energy from a charging station to an electric vehicle was described by way of example. As the person skilled in the art immediately recognizes, the invention can in general refer to the connection between a coil and a power electronic unit, ie equally well to the primary side of an inductive transmission device, in which only the direction of the power flow between the primary coil and the local power electronic unit is reversed as compared to the secondary side. Furthermore, from the described embodiment for a person skilled in the art variation possibilities for the realization of the invention. In particular, depending on the available cross-sectional area of the channel 7, more than two cables could be used, and the number of wires per cable could be as small as four, even two or more than four. Such and similar modifications are at the discretion of the skilled person and are intended to be encompassed by the claims.

Claims

Expectations

Device for the inductive transmission of electrical energy with a coil (2), which can be inductively coupled to another coil by suitable positioning of the two coils relative to one another for energy transmission, with a power electronic unit (3) for extracting electrical power from the coil (2) or for delivering electrical power into the coil (2) and with a supply line (4, 5) which connects the coil (2) to the power electronic unit (3), characterized in that the supply line (4, 5) consists of at least two multi-core Cables (4; 5) with insulated cores (4A, 4B, 4C, 4D; 5A, 5B, 5C, 5D) and that the connection of each connection (2A; 2B) of the coil

(2) with an assigned connection of the power electronic unit

(3) consists of a plurality of cores (5A, 5C, 4B, 4D; 4A, 4C, 5B, 5D) of the multi-core cables (4, 5).

Device according to claim 1, characterized in that each connection (2A; 2B) of the coil (2) is connected to the respectively assigned connection of the power electronic unit (3) by wires (5A, 5C, 4B, 4D; 4A, 4C, 5B, 5D ) of at least two different cables (4, 5) is connected.

Device according to claim 2, characterized in that the same number of wires (5A, 5C, 4B, 4D; 4A, 4C, 5B, 5D) of each individual cable (4, 5) each of the two connections (2A; 2B) of the coil (2 ) with the assigned connection of the power electronic unit (3).

Device according to claim 3, characterized in that in the cross section of each cable (4; 5) the wires (4A, 4B, 4C, 4D; 5A, 5B, 5C, 5D) are arranged symmetrically and the connections of the coil (2A; 2B) so are assigned that cores (5A, 5C; 4B, 4D; 4A, 4C, 5B, 5D) with the same current direction are always arranged in pairs symmetrically to the center of a cable (4, 5) and extend in the circumferential direction on each through the center of the cable (4, 5) and the centers of two mutually symmetrical wires (4A , 4C; 4B, 4D; 5A, 5C; 5B, 5D) alternate the defined circle of wires with opposite current directions.

Device according to one of claims 1 to 4, characterized in that all wires (4A, 4C, 5B, 5D) of a cable which connect a connection (2B) of the coil (2) to the same connection of the power electronic unit (3) are used uniform distribution of the total current between the individual wires (4A, 4C, 5B, 5D) cyclically in pairs with opposite current directions through closed magnetic cores (8, 9, 10, 11).

Device according to one of claims 1 to 5, characterized in that the total cross section of each of the multi-core cables (4, 5) does not exceed the height of the coil (2).

Device according to one of claims 1 to 6, characterized in that the coil (2) is a secondary coil which can be mounted on a vehicle (1) and is intended for power consumption.

Device according to one of claims 1 to 6, characterized in that the coil is a primary coil which can be mounted on a stationary unit and is intended for power output.