DE102013217877A1 - Device for inductive energy transmission and method for inductive energy transmission - Google Patents

Abstract

The present invention provides inductive energy transfer between a primary coil and a secondary coil. Changes in the coupling factor between the primary and secondary coils, which occur for example due to variations in the air gap or an offset between the primary coil and secondary coil, are compensated by adapting the coil windings actively involved in the primary or secondary coil. Thus, a coupling inductance between primary and secondary coil can be kept almost constant even with variable coupling factor or adapted to a specific charging power. As a result, an optimization of the efficiency or other parameters is possible. Furthermore, compatibility between different primary and secondary coil arrangements can be achieved.

Description

The present invention relates to an apparatus and method for inductive power transmission. In particular, the present invention relates to an inductive energy transfer from a primary coil arrangement to a secondary coil arrangement which can be inductively coupled to the primary coil arrangement.

State of the art

Electric vehicles powered by an electric motor alone are known. In addition, plug-in hybrid vehicles are known, the drive is effected by a combination of an electric motor and another drive machine. In this case, the electrical energy for driving the electric motor is provided by an electrical energy store, for example a traction battery. After the energy storage is completely or partially discharged, it is necessary to recharge the energy storage. There are various approaches for charging the energy store.

On the one hand, it is possible to electrically connect the electric vehicle to a charging station by means of a suitable charging cable. To do this, a user must establish an electrical connection between the electric vehicle and the charging station. This can be perceived as unpleasant especially in bad weather conditions, such as rain. Due to the very limited electrical range of electric and plug-in hybrid vehicles this cable connection must also be made very often by the user, which is perceived by many users as a major disadvantage of electric vehicles compared to conventional vehicles.

On the other hand, therefore, there are also wireless solutions for transmitting energy from a charging station to an electric vehicle. In this case, the energy is transferred from the charging station via an alternating magnetic field from a primary coil to a secondary coil in the electric vehicle. Subsequently, the energy received by the secondary coil is converted into electrical energy and supplied to the traction battery in the vehicle. Resonance networks are used on both the primary and the secondary side to enable efficient energy transmission. For this purpose, different resonance networks are known.

In all these solutions, it is necessary that the electric vehicle with the secondary coil is arranged as precisely as possible over the primary coil of the charging station. Depending on the distance and position of the primary coil and the secondary coil to each other, different influences on the coil system. The publication DE 42 36 286 A1 discloses a system for non-contact energy transfer when charging the battery of a vehicle, in which the primary coil and / or the secondary coil can be varied in position after the vehicle is parked. The secondary coil is mounted on the vehicle such that it is openly accessible during energy transmission.

There is a need for inductive power transfer which is easily adaptable to variations in the coupling between the primary and secondary coils. In addition, there is a need for an inductive energy transfer, which allows an improved energy transfer even with non-optimal alignment of primary and secondary coil and does not require a mechanically moving device.

Disclosure of the invention

In one aspect, the present invention provides a device for inductive power transmission having a primary coil assembly having a first number of primary windings, the primary windings adapted to be traversed by an alternating electrical current during inductive power transmission and a secondary coil assembly configured therefor is to provide an alternating electrical voltage between a second number of secondary windings, wherein the first number of primary windings of the primary coil assembly and / or the second number of secondary windings of the secondary coil assembly is variable.

According to a further aspect, the present invention provides a method for inductive energy transmission from a primary coil arrangement to a secondary coil arrangement inductively coupled to the primary coil arrangement, comprising the steps of providing the primary coil arrangement; the provision of the secondary coil assembly; and adapting a first number of primary windings in the primary coil arrangement, which are traversed by an alternating electrical current during the inductive energy transmission and / or adapting a second number of secondary windings in the secondary coil arrangement, between which an alternating electrical voltage is provided during the inductive energy transmission.

Advantages of the invention

The present invention is based on the idea of the properties of the primary coil and / or the secondary coil to adapt to external conditions. By selectively switching on or off individual windings on the primary and / or secondary side while the inductors can be adjusted so that a coupling inductance between the two coils is kept as constant as possible even with variable coupling factor. Thus, it is possible, for example, to significantly improve the efficiency or other optimization variables.

Due to the inventive variations in the primary coil and / or the secondary coil, it is possible to adapt the coil system to the respective conditions. Thus, the operating conditions can be optimized. For example, it is possible to respond to deviations in the air gap between the primary and secondary coils. It is also possible to optimize the coil system for the power to be transmitted.

According to one embodiment, the primary coil arrangement has a predetermined number of base turns as well as a first extension unit. The first expansion unit is designed to add one or more additional turns to the base turns of the primary coil arrangement. A primary coil arrangement with more than one expansion unit is also possible. By such a circuit arrangement, a simple adaptation of the active during the energy transfer primary windings in the primary coil assembly is made possible.

According to a specific embodiment, the first expansion unit comprises a first compensation device, which is designed to adapt a resonance frequency in the primary coil arrangement. For example, for this purpose, the additional windings in the expansion unit can be coupled with a compensation capacity matched to the additional windings. Thus, even with variation of the number of turns in the primary coil arrangement, the resonance frequency of the system can be adapted to the desired operating frequency.

According to a further embodiment, the secondary coil arrangement has a predetermined number of ground coils and a second expansion unit. The second extension unit is designed to add one or more supplementary turns to the base turns of the secondary coil arrangement. In this way, a simple adaptation of the active secondary windings in the secondary coil is possible.

In a specific embodiment, the second expansion unit has a second compensation device which is designed to adapt a resonance frequency in the secondary coil arrangement. Thus, it is also possible on the secondary side to adjust the resonance frequency of the system to the desired operating frequency.

According to a further embodiment, the inductive power transmission device further comprises a control unit which is adapted to adapt the first number of primary windings in the primary coil arrangement and / or the second number of secondary windings in the secondary coil arrangement. Such a control unit enables an efficient and optimized adaptation of the active windings in the primary coil and / or the secondary coil.

According to a further embodiment, the inductive power transmission device further comprises a control unit which is designed to measure a current and / or a voltage in the primary coil arrangement and / or the secondary coil arrangement and the first number of primary windings in the primary coil arrangement and / or the second Number of secondary windings in the secondary coil assembly as a function of the measured current and / or the measured voltage to adapt. In this way, an efficient adjustment of the coil ratios is possible.

According to a further embodiment, the control unit adjusts the first number of primary windings in the primary coil arrangement and / or the second number of secondary windings in the secondary coil arrangement as a function of the power to be transmitted. In this way it is possible, even with variations in the power to be transmitted to always allow optimal inductive energy transfer.

According to yet another embodiment, the control unit adjusts the first number of primary windings in the primary coil assembly and / or the second number of secondary windings in the secondary coil assembly at the beginning of an energy transfer. Thus, from the beginning the winding ratios and thus also the coupling inductance can be adapted to the respective transmission conditions.

According to another embodiment, the control unit dynamically adjusts the first number of primary turns in the primary coil assembly and / or the second number of secondary turns in the secondary coil assembly during energy transfer. Such an adjustment may be either continuous, cyclical during fixed predetermined time intervals or upon the arrival of predefined events, such as variations in current, voltage or power. A dynamic adaptation makes it possible to react to variations that occur during the energy transmission and to optimize the transmission conditions during the entire energy transmission.

According to a further embodiment, the control unit adjusts the first number of primary windings in the primary coil arrangement and / or the second number of secondary windings in the secondary coil arrangement to a power to be transmitted. Thereby, e.g. the primary coil assembly is adapted to be compatible with different secondary coil assemblies. Similarly, the secondary coil arrangement can also be adapted so that it is compatible with different primary coil arrangements.

According to a further embodiment, the individually switchable coil parts of the primary coil arrangement and / or the secondary coil arrangement consist of turns with different conductor cross-sections and / or different high-frequency hubs.

In accordance with yet another embodiment, the charging device comprises a plurality of different primary coil arrangements and / or secondary coil arrangements which are optimized for different charging powers, wherein in each case a primary coil arrangement and a secondary coil arrangement is selected as a function of the charging power to be transmitted.

Further features and advantages of embodiments of the invention will become apparent from the following description with reference to the accompanying drawings.

Brief description of the drawings

Show it:

1 1 is a schematic representation of a vehicle being loaded by means of an inductive energy transfer device according to an embodiment;

2 a schematic representation of a device for inductive energy transmission according to another embodiment; and

3 : A schematic representation of a method for inductive energy transmission, as it is based on a further embodiment of the present invention.

Description of embodiments

1 shows an electric vehicle 3 with a battery 30 , This battery 30 is about a device 1 charged for inductive energy transfer. For this purpose, an energy source 4 , For example, taken from an electrical supply network energy. This energy becomes a primary coil arrangement 10 stimulated. In this case, the primary coil arrangement 10 traversed by an electrical alternating current. The frequency at which the primary coil assembly 10 is excited, is preferably in the range between 10 and 150 kHz. However, other frequencies below or below are also possible. The circuit arrangement of the device 1 For inductive energy transfer advantageously has resonance elements, which are preferably tuned so that the device 1 has a resonant frequency close to the desired operating frequency. Preferably, that of the energy source 4 supplied voltage thereby provided by a suitable inverter circuit in the desired operating frequency.

By exciting the primary coil assembly 10 With the electrical alternating current, an alternating magnetic field is generated, which in the secondary coil assembly 20 induced an electrical alternating voltage. This electrical alternating voltage is at the output of the secondary coil assembly 20 provided and after appropriate treatment, such as a rectification, the battery 30 of the vehicle 3 made available.

In the design of conventional charging systems with an inductive energy transfer, it is assumed that between the primary coil assembly 10 and the secondary coil assembly 20 a defined air gap is present. Corresponding parameters are for example in VDE-AR-E 2122-4-2 Are defined. Will the vehicle 3 with the secondary coil assembly 20 but not optimally over the primary coil assembly 10 turned off, a conventionally dimensioned transmission system is not optimally adapted. On the one hand, this has an influence on the parameters of the coil system per se, such as the currents, voltages or losses. On the other hand, the deviation from the optimal operating point also affects the power electronics and the control, etc. Therefore, a conventional system does not work optimally with deviating air gap.

2 shows a schematic representation of a device 1 for inductive energy transmission according to an embodiment of the present invention. The primary coil assembly 10 includes a first coil part with a first predetermined number N _PB of base turns 11 , Furthermore, the primary coil arrangement 10 a first expansion unit 12 on. This extension unit 12 includes one or more coil parts with first additional turns 12 , For better intuition is in 2 only one such coil part with additional turns 12 shown. In addition, any number of additional coil parts with additional turns is possible in order to additionally increase the flexibility in the adaptation. The activation of the primary coil arrangement 10 and the selection of the current-carrying windings in the primary coil assembly 10 takes place by the primary-side control unit 15 ,

The device 1 for inductive energy transmission further comprises a secondary coil assembly 20 , This secondary coil arrangement 20 is arranged during the inductive energy transfer such that one of the primary coil assembly 10 generated alternating magnetic field in the secondary coil assembly 20 couples. The secondary coil arrangement 20 comprises a base coil with a predetermined number N _SB of ground turns 21 , Furthermore, the secondary coil arrangement comprises a second expansion unit with one or more second supplementary windings 22 , Again, for better intuition in 2 just a group of supplementary turns 22 shown. In addition, however, it is also possible analogously to the primary coil arrangement, in addition to integrate additional supplementary windings in the expansion unit. The supplementary turns 22 can all have the same number N _SZ . Alternatively, it is also possible that the number N _SZ for each group of supplementary turns 22 varied.

In the in 2 illustrated embodiment are both in the primary coil assembly 10 , as well as in the secondary coil assembly 20 each extension units with additional turns 12 and 22 shown. Depending on the application, it is also possible that only in the primary coil assembly 10 or in the secondary coil assembly 20 an extension unit for adjusting the number of turns of the coil is present. In this case, the respective other coil arrangement can be carried out without such an expansion unit.

For energy transfer from the primary coil assembly 10 to the secondary coil assembly 20 becomes the primary coil assembly 10 now excited by an alternating electric current. The alternating magnetic field generated thereby couples into the secondary coil arrangement 20 induced in the secondary coil assembly 20 an alternating electrical current at the output of the secondary coil assembly 20 can be provided. Varies the location between primary coil assembly 10 and secondary coil assembly 20 , it comes depending on the offset of the two coils and the intermediate air gap to fluctuations in the coupling factor k. In the case of a fluctuating coupling factor k, the coupling inductance M between the primary coil arrangement 10 and secondary coil assembly 20 To keep as constant as possible, the number of turns actively involved in the transmission of energy in the primary coil assembly 10 and / or the secondary coil assembly 20 be varied. For this it is possible, in addition to the base turns 11 the primary coil assembly 10 add more turns by suitable switching elements. As switching elements in this case both mechanical, as well as electrical switching elements come into question. It is basically possible, in addition to the windings N _PB further Zusatzwindungen 12 to add individually. However, in order to minimize the number of required switching elements and the associated switching effort, it is also possible, the additional turns 12 in groups of several turns and in each case one or more such groups of additional turns 12 to the basic turns 11 add switch.

The device 1 for inductive energy transfer is preferably operated in the vicinity of a fixed predefined operating frequency. In this case, the resonance elements of the device 1 for inductive energy transmission dimensioned so that the device 1 for inductive energy transmission has a resonant frequency in the range of the operating frequency. As by adding or removing additional turns 12 Changing the resonant frequency of the entire inductive energy transfer device is a compensation of the additional inductance by the additional turns 12 required. This can be done in parallel to the addition or removal of additional turns 12 at the same time a corresponding capacitance C _PZ in the primary coil assembly 10 be added or removed. Preferably, each group of Zusatzwindungen 12 simultaneously coupled with a suitable device for compensation of the additional inductance. For example, every Zusatzwindung 12 or any group of additional turns 12 be interconnected with a correspondingly dimensioned capacitor C _PZ .

Analogous to the variation of the active coil windings of the primary coil arrangement 10 is also a variation of the active coil turns of the secondary coil assembly 20 possible. It can by a control device 25 in each case the desired number of supplementary turns 22 to the ground turns 21 to be added. Again, adding or removing individual supplementary turns or groups of supplementary turns 22 possible. Analogous to the compensation of the variation in the resonance frequency by additional components, as related to the primary coil assembly 10 has been described, a compensation of the resonance frequency by suitable compensation elements C _{SZ is also} possible.

The number of primary windings actively involved in the energy transfer in the primary coil assembly 10 and / or the secondary coil assembly 20 is preferably adapted so that even with variable coupling factor k as constant as possible Koppelinduktivität M between primary coil assembly 10 and secondary coil assembly 20 established.

In addition, various optimization parameters are possible. For example, based on determined or calculated values for currents, voltages, magnetic fields in the air gap between primary and secondary coil arrangement, etc., the energy transfer can be adjusted so that an optimized efficiency for the energy transfer results. Alternatively, it is also possible to adapt the active coil turns for further optimization parameters.

For example, depending on the power to be transmitted from the primary coil assembly 10 to secondary coil arrangement 20 different numbers of coil turns are selected. For example, an adaptation of the primary coil arrangement 10 and / or secondary coil assembly 20 at previously defined charging power levels possible. In addition, it is also conceivable that previously the relative position between primary coil assembly 10 and secondary coil assembly 20 is determined and based on the number of actively involved in the energy transfer coil windings in primary coil assembly 10 and secondary coil assembly 20 is determined.

For an optimum adjustment of the coil windings actively involved in the energy transmission, it is advantageous to determine the number of coil windings actively involved in the energy transmission even before the energy transmission begins or directly at the start of the energy transmission, and then the primary coil arrangement 10 and / or the secondary coil assembly 20 adjust accordingly. In addition, it may also be advantageous to continuously monitor the energy transfer, and then, if appropriate, the number of active coil windings in the primary coil arrangement 10 and / or secondary coil unit 20 adapt. For this purpose, for example, continuously a current flow in the primary coil unit 10 be monitored. In addition, it is also possible to monitor and determine further parameters. During the energy transfer, it is found that by varying the active coil windings in the primary coil arrangement 10 or secondary coil unit 20 an optimized energy transfer is possible, so then the number of coil windings actively involved in the energy transfer can be adjusted. Alternatively, an adaptation is only possible if the determined parameters exceed a predetermined threshold. Thus, a frequent switching back and forth between the coil turns involved may be avoided if necessary.

3 shows a schematic representation of a method 100 for operating an inductive energy transfer from a primary coil assembly 10 to a secondary coil assembly 20 as underlying an embodiment of the present invention. In step 110 becomes the primary coil assembly 10 provided. The primary coil assembly 10 includes the previously described components, such as base coils 11 and extension unit with additional windings 12 coming from the control unit 15 can be controlled.

In step 120 becomes a secondary coil arrangement 20 provided. This secondary coil arrangement 20 also includes the components described above, such as basic turns 21 , as well as extension unit with supplementary windings 22 passing through the control unit 25 can be added to the ground turns or switched off.

In step 130 becomes the first number of primary turns in the primary coil assembly 10 adjusted, which are traversed during the inductive energy transfer from an alternating electrical current. Additionally or alternatively, a second number of secondary windings in the secondary coil arrangement 20 adapted, this secondary coil arrangement 20 as also described above during the inductive energy transfer provides an electrical AC voltage.

In summary, the present invention relates to an inductive energy transfer between a primary coil and a secondary coil. Changes in the coupling factor between the primary and secondary coils, which occur for example due to variations in the air gap or an offset between the primary coil and secondary coil, are compensated by adapting the coil windings actively involved in the primary or secondary coil. Thus, a coupling inductance between primary and secondary coil can be kept almost constant even with variable coupling factor or adapted to a specific charging power. As a result, an optimization of the efficiency or other parameters is possible. Furthermore, compatibility between different primary and secondary coil arrangements can be achieved.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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

• DE 4236286 A1 [0005]

Cited non-patent literature

• VDE-AR-E 2122-4-2 [0030]

Claims (10)

Contraption ( 1 ) for inductive energy transmission, with a primary coil arrangement ( 10 ), which has a first number of primary windings, wherein the primary windings are adapted to be traversed during an inductive energy transfer from an alternating electrical current, and a secondary coil assembly ( 20 ) configured to provide an alternating electrical voltage between a second number of secondary windings, wherein the first number of primary windings in the primary coil assembly ( 10 ) and / or the second number of secondary windings in the secondary coil arrangement ( 20 ) is changeable. Contraption ( 1 ) according to claim 1, wherein the primary coil arrangement ( 10 ) a first predetermined number (N _{P, B} ) of base turns ( 11 ) and a first expansion unit, wherein the first expansion unit is adapted to one or more additional turns ( 12 ) to the first number (N _{P, B} ) of base turns ( 11 ) of the primary coil assembly ( 10 ). Contraption ( 1 ) according to claim 2, wherein the first expansion unit comprises a first compensation device (C _{P, Z} ), which is adapted to a resonance frequency in the primary coil arrangement ( 10 ). Contraption ( 1 ) according to one of claims 1 to 3, wherein the secondary coil arrangement ( 20 ) a second predetermined number (N _{S, B} ) of ground turns ( 21 ) and a second expansion unit, wherein the second expansion unit is adapted to one or more supplementary turns ( 22 ) to the second number (N _{S, B} ) of ground turns ( 21 ) of the secondary coil arrangement ( 20 ). Contraption ( 1 ) according to one of claims 1 to 4, further comprising a control unit ( 15 . 25 ), which is adapted to the first number of primary windings in the primary coil assembly ( 10 ) and / or the second number of secondary windings in the secondary coil arrangement ( 20 ). Contraption ( 1 ) according to claim 5, wherein the control unit ( 15 25 ) is adapted to generate a current and / or a voltage in the primary coil arrangement ( 10 ) and / or the secondary coil arrangement ( 20 ) and the first number of primary turns in the primary coil assembly ( 10 ) and / or the second number of secondary windings in the secondary coil arrangement ( 20 ) as a function of the measured current and / or the measured voltage. Contraption ( 1 ) according to claim 5 or 6, wherein the control unit ( 15 . 25 ) the first number of primary turns in the primary coil assembly ( 10 ) and / or the second number of secondary windings in the secondary coil arrangement ( 20 ) depending on a power to be transmitted. Contraption ( 1 ) according to one of claims 5 to 7, wherein the control unit ( 15 . 25 ) the first number of primary turns in the primary coil assembly ( 10 ) and / or the second number of secondary windings in the secondary coil arrangement ( 20 ) at the beginning of an energy transfer adapts. Contraption ( 1 ) according to one of claims 5 to 8, wherein the control unit ( 15 . 25 ) the first number of primary turns in the primary coil assembly ( 10 ) and / or the second number of secondary windings in the secondary coil arrangement ( 20 ) dynamically adapts during an energy transfer. Procedure ( 100 ) for operating an inductive energy transfer from a primary coil arrangement ( 10 ) to one with the primary coil assembly ( 10 ) inductively coupled secondary coil arrangement ( 20 ), with the steps: Deploy ( 110 ) of the primary coil assembly ( 10 ); Provide ( 120 ) of the secondary coil arrangement ( 20 ); and customizing ( 130 ) a first number of primary windings in the primary coil arrangement ( 10 ), which are traversed by an alternating electrical current during the inductive energy transmission and / or adjusting a second number of secondary windings in the secondary coil arrangement (US Pat. 20 ), between which an electrical alternating voltage is provided during the inductive energy transmission.

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