DE102022201628A1 - Inductive charging device for wireless energy transfer - Google Patents

Abstract

The present invention relates to an inductive charging device (1) for wireless energy transmission, the inductive charging device (1) having a device (8) for actively adjusting a capacity, which comprises two switches (16). Improved precision and safety of the inductive charging device (1). achieved in that a comparator (36) and a voltage limiter (42) connected between the switch (16) and the comparator (36) are provided for the respective switch (16) of the device (8). The invention also relates to a wireless Energy transmission system (1) with such an induction charging device (1).

Description

The present invention relates to an inductive charging device for wireless energy transmission, which has a device for actively adjusting a capacity. The invention also relates to a wireless energy transmission system, which is used in particular to charge a battery in a motor vehicle, with such an induction charging device.

Wireless power transmission systems are usually based on the induction principle. In this case, a generally stationary inductive charging device transmits energy inductively to another, generally mobile, inductive charging device. For these inductive charging devices to work together effectively, it is advantageous for these inductive charging devices to be coordinated with one another. In particular, in order to be able to operate the same stationary inductive charging device with different mobile inductive charging devices or vice versa, it is desirable to be able to adapt certain parameters in the stationary inductive charging device and/or in the mobile inductive charging device as required. For this purpose it should usually be possible to adjust the capacity of the inductive charging device.

Such a wireless energy transmission system is from EP 3 365 958 B1 known. In the stationary inductive charging device, the energy transmission system comprises a device for actively adjusting a capacitance and a control circuit for controlling the device. The device for variably adjusting the capacitance includes two series-connected capacitors and two switches, each designed as a MOSFET. The switches are connected in series and arranged anti-serially to one another, with the sources of the switches being electrically connected to one another. The drains of the switches are each electrically connected to a terminal of an associated capacitor and electrically to a terminal of the device. The gate connections and thus control connections of the switches are coupled to the control circuit. When successive current zero crossings are detected by the device, one of the two switches is closed in each case. The effective capacity of the device can be set here by the duration for which the switches are closed and thus conduct. A comparator is connected between the switches and the control circuit for the respective switch in order to detect voltage zero crossings through the capacitors. Each comparator is electrically connected to the source and drain of the associated switch of the device. The output connection of the respective comparator is also electrically connected to the control circuit.

The present invention is concerned with the task of specifying improved or at least different embodiments for an inductive charging device and for a wireless energy transmission system of the type mentioned at the outset, which are characterized in particular by increased precision and/or safety and/or efficiency.

According to the invention, this object is achieved by the subject matter of independent claim 1 . Advantageous embodiments are the subject matter of the dependent claims.

The present invention is based on the general idea, in an induction charging device for wireless energy transmission, which includes a device for actively adjusting a capacitance with two switches and a capacitor arrangement with at least one capacitor, for detecting zero crossings of the voltage through the switch or the capacitor arrangement Use device comparators, wherein the voltage applied to the comparators is limited by means of an associated voltage limiter. As a result, the voltage present at the respective comparator corresponds to the voltage present at the associated switch/capacitor arrangement of the device up to said limit and is correspondingly limited above this limit. Compared to the prior art, where the limited operating voltages of comparators require a reduction in the voltages present at the switches/the capacitor arrangement of the device by means of voltage dividers and differential amplifiers, the voltage present at the comparators has an upper limit. This allows the voltage zero crossings to continue to be determined reliably. In addition, the inaccuracies present in differential amplifiers and caused in particular by intrinsic parasitic capacitances and/or impedance when reducing the voltage applied to the switches/the capacitor arrangement of the device, which lead to a considerable inaccuracy in the detection of the voltage zero crossings, are avoided in this way . In this way, the jitter present in comparators and the associated additional inaccuracies in the detection of the zero crossings are also prevented or at least significantly reduced. Consequently, the idea according to the invention leads to a precise detection of the voltage zero crossings. As a result, processes carried out by detecting the voltage zero crossings can be implemented more accurately and precisely. out of it result in increased safety and/or efficiency of the inductive charging device.

According to the idea of the invention, the inductive charging device includes the device for actively adjusting the capacity. The device includes a capacitor arrangement with at least one capacitor and two switches. The capacitor arrangement has two electrical connections, which are also referred to below as the first capacitor connection and the second capacitor connection. The respective switch includes a control connection for controlling the switch and two further electrical connections through which an electric current can flow when the switch is in the closed state. The device thus has a first switch with a first first switch connection, a second first switch connection and a first switch control connection. Furthermore, the device comprises a second switch, which has a first second switch connection, a second second switch connection and a second switch control connection. In this case, the second first switch connection is electrically connected to the first capacitor connection. Furthermore, the second second switch terminal is electrically connected to the second capacitor terminal. The inductive charging device has two voltage limiters which are connected between the switches of the device and comparators of the inductive charging device for detecting voltage zero crossings. The inductive charging device thus has a first comparator for the first switch and a second comparator for the second switch. The respective comparator has two input terminals and one output terminal. The inductive charging device thus has a first comparator with a first first comparator connection and a second first comparator connection, as well as a first comparator output connection. Furthermore, the inductive charging device has a second comparator with a first second comparator connection and a second second comparator connection as well as a second comparator output connection. A first voltage limiter is connected between the first switch and the first comparator. The first voltage limiter is designed in such a way that it limits the voltage present between the first first comparator connection and the second first comparator connection. Furthermore, a second voltage limiter is connected between the second switch and the second comparator. The second voltage limiter is designed in such a way that it limits the voltage present between the first second comparator connection and the second second comparator connection. The inductive charging device has at least one device coupled to the comparator output connections, which is designed in such a way that it uses the comparators to detect voltage zero crossings through the switch/capacitor arrangement and is also referred to below as a detection device.

In principle, the detection device can be configured as desired. In particular, the recognition device can be an evaluation circuit or have an evaluation circuit.

The inductive charging device advantageously has a control circuit for switching the switches of the device, ie the first switch and the second switch. For this purpose, the control circuit is electrically coupled to the control terminals of the switches of the device. Thus, the control circuit is coupled to the first switch control port and the second switch control port. The control circuitry is designed to actively adjust the capacitance of the device by closing and opening the switches.

The control circuit is advantageously designed in such a way that it periodically closes and opens the switches of the device for an associated period of time in each case during successive current zero crossings through the device. That is, the control circuit is configured to adjust the effective capacitance of the device by applying a first control signal to the first switch control terminal upon a first zero current crossing through the device such that the first switch is closed for a first period of time. Further, upon a second zero current crossing following the first zero current crossing, the device applies a second control signal to the second switch control terminal such that the second switch is closed for a second period of time. The first switch and the second switch are preferably closed and opened periodically and alternately during the successive current zero crossings.

The control circuit is advantageously designed to recognize zero current crossings.

The detection of the voltage zero crossings by means of the comparators and the detection device, also referred to below as voltage zero crossing detection, can be used for any purpose.

It is conceivable to take into account the voltage zero crossing detection in the control circuit. The control circuit and the detection device are or can be coupled to one another. It is also conceivable that the tax Circuit and the detection device at least partially correspond to each other.

The voltage zero crossing detection is advantageously used for monitoring purposes and/or for controlling the inductive charging device. In particular, the voltage zero crossing detection is used for monitoring functions and/or control functions. In this way, for example, the actual conduction duration of the switches of the device and consequently in particular the respective duration can be recognized and/or determined and/or monitored.

The limitation of the voltage present at the respective comparator is expediently adapted to the corresponding design of the comparator. This means that the limitation does not exceed the permissible operating voltage or input voltage of the comparator, or that the operating voltage of the comparator is equal to or greater than the limitation of the voltage. For example, for a comparator designed to operate at 15V, the voltage limit is 15V or less. The voltage limiters are designed accordingly.

In principle, the comparators and the associated voltage limiters can be designed differently and/or designed for different voltages.

The comparators are preferably identical. It is also preferred if the voltage limiters are identical.

In preferred embodiments, at least one of the voltage limiters, advantageously the respective voltage limiter, has a switch and a resistor.

It is therefore preferred if the first voltage limiter has a switch and a resistor, which are referred to below as the third switch and as the first resistor. Furthermore, the second voltage limiter has a switch and a resistor, which are referred to below as the fourth switch and as the second resistor. The third switch and the fourth switch each have three connections, analogous to the first switch and the second switch. The third switch thus has a first third-switch connection, a second third-switch connection and a third-switch control connection. In addition, the fourth switch has a first fourth-switch connection, a second fourth-switch connection and a fourth-switch control connection. Each resistor has two terminals. Thus, the first resistor has a first first resistor terminal and a second first resistor terminal. In addition, the second resistor has a first second resistor connection and a second second resistor connection. The first first switch connection is electrically connected to the first first resistance connection and the first third switch connection is electrically connected to the second first resistance connection. Furthermore, the first second switch connection is electrically connected to the first second resistance connection and the first fourth switch connection is electrically connected to the second second resistance connection. In addition, the first first resistance connection is electrically connected to the first first comparator connection and the second first resistance connection is electrically connected to the second first comparator connection. Furthermore, the first second resistance connection is electrically connected to the first second comparator connection and the second second resistance connection is electrically connected to the second second comparator connection. A simple design of the respective voltage limiter is thus easily implemented and, in addition, an effective and reliable limitation of the voltage present at the associated comparator is achieved. Furthermore, interference, in particular interference signals, at the comparator are prevented or at least reduced in this way.

With the respective resistor and the switch between the device and the comparator, a limited voltage applied to the associated comparator is realized in the manner of a source follower for the respective switch of the device. This means that the third switch and the first resistor act together as a voltage limiter for the first comparator in the manner of a source follower of the first switch. In addition, the fourth switch and the second resistor act together as a voltage limiter for the second comparator in the manner of a source follower of the second switch.

Preferably, at least one of the switches, advantageously the respective switch, is a transistor. Particularly preferably, at least one of the switches, advantageously the respective switch, is a MOSFET. In this case, the first switch connection corresponds to a source connection, the second switch connection to a drain connection and the control connection to a gate connection of the transistor. Inexpensive production and simplified control of the switches are thus achieved.

In principle, the control circuit can be designed in any way. The control circuit expediently has at least one integrated circuit, in particular a driver IC.

As described above, the capacitor arrangement comprises at least one capacitor sator. In particular, the capacitor arrangement can comprise a single capacitor. If the capacitor arrangement includes two or more capacitors, these are expediently connected in series. In this case, the capacitor connections suitably correspond to the free connections of the two outermost capacitors.

In preferred embodiments, at least one of the comparators, preferably the respective comparator, is electrically isolated from the detection device. This means that the output connection of at least one of the comparators is galvanically isolated from the detection device. The galvanic isolation, for example, avoids or at least reduces ground loops to a certain extent or limit frequency. As a result, line-bound interference cannot propagate, or at least to a reduced extent. In this way, reduced disturbances during operation and/or increased precision in the detection of the voltage zero crossings are achieved.

In principle, the respective comparator can be galvanically isolated from the detection device as desired.

For this purpose, a logic isolator, in particular an optocoupler, is preferably provided between at least one of the comparators and the control circuit. This means that at least one of the output connections is coupled to the control circuit via a logic isolator, in particular via an optocoupler. A simple and reliable electrical isolation of the detection device from the respective associated comparator is thus achieved.

In principle, the switches of the device, ie the first switch and the second switch, can be arranged and/or connected in any way in the device, provided they allow an associated flow through the device by switching using the control circuit.

The device, in particular the control circuit, is designed in such a way that the respective switch of the device is assigned to a current direction. For example, the first switch can be responsible for the positive half-cycle of the alternating current and the second switch for the negative half-cycle of the alternating current, or vice versa.

In particular, the switches of the device can be provided in series in a current path of the device and in anti-series relation to one another. In this case, the first switch connections are electrically connected to one another. That is, the first first switch terminal and the first second switch terminal are electrically connected to each other.

The voltage across the capacitor arrangement advantageously also corresponds to the voltage across the switch path. If the respective switch conducts, the voltage across the capacitor arrangement is zero. If, on the other hand, the switch in the current direction blocks, a voltage is present across the capacitor arrangement. Therefore, by checking to see if the switches are live or conducting, it is possible to determine the voltage across the device.

Embodiments are preferred in which the first switch connections of the switches of the device are electrically isolated from one another. That is, the first first-switch terminal and the first two-switch terminal are electrically isolated from each other. Consequently, the first switch and the second switch can be controlled independently and individually. In this way, resonances between the two switches can be prevented or at least reduced. As a result, the capacity that can be adjusted with the device can be adjusted more precisely. It is thus also possible to improve the switching behavior, in particular when high-frequency interference is damped. This also leads to increased efficiency in wireless power transmission.

The switch terminals of the switches of the device, which are electrically isolated from one another, also allow the current paths of the two switches in the device to be separated. This means that an associated current path is provided in each case for incoming currents and return currents through the device. This leads to a further reduction of resonances and consequently a further improvement in efficiency. By separating the current paths for the forward currents and return currents, it is also possible to operate the device and thus the induction charging device with an increased voltage.

The device advantageously allows three different electrical currents through the device. If the respective switch of the device is open in the associated current direction or in the associated half-cycle of the alternating current, the entire current flows through the capacitor. In the closed state of the first switch, the electric current flows via the first switch and thereby bypasses the second switch, with the associated current path also being referred to below as the outgoing path. The first switch is advantageously closed when an associated phase of the electrical voltage is present, whereas the second switch is open while this phase is present. In addition, when the second switch is closed, the electrical current can flow via a current path leading through the second switch, which is also referred to below as the return path. Here, the outward path and the Capacitor arrangement bypassed. The return path is realized by closing the second switch and opening the first switch. In this case, the second switch is expediently closed and the first switch is opened when an electrical voltage with a second phase directed in the opposite direction to the first phase is applied to the device. The same applies to the outward path.

The effective capacity of the device can be actively adjusted by means of the respective duration of the switch-on time and thus the duration and/or the respective switch-on angle. In this case, for example, a longer period of time results in an increased capacity of the device.

wobei C₁ die feste Kapazität der Kondensatoranordnung ist. Zudem ist <p der Einschaltwinkel und entspricht der in einen Winkel umgerechneten Einschaltdauer. In particular, the capacitance of the device and thus the effective capacitance when a current flows only via the capacitor arrangement is dominated by the capacitance of the capacitor arrangement, in particular corresponds to the capacitance of the capacitor arrangement. With a current flow only through the switches, the effective capacitance approaches infinity. In particular, the capacitance of the device and consequently the effective capacitance C _ef with a current flow only via the switches tends to be: $${\text{C}}_{\text{ef}}={\text{<figure-callout id="1" label="C" filenames="DE102022201628A1\_0005.png,DE102022201628A1\_0007.png" state="{{state}}">C</figure-callout>}}_1\cdot \frac{1}{2-\frac{\left(2\phi -\text{sin}2\phi \right)}{\pi }}$$

where C ₁ is the fixed capacitance of the capacitor array. In addition, <p is the switch-on angle and corresponds to the switch-on time converted into an angle.

In particular, φ = 90° means that the associated switch never carries the current, and φ= 180° means that the associated switch conducts permanently, with this formula only applying to the fundamental wave, and with the following applying: $$90°\le \phi \le 180°.$$

By actively adjusting the capacitance, the device also actively adjusts the impedance, since the impedance Z is inversely proportional to the effective capacitance: $$\text{Z}\sim \frac{1}{{\text{C}}_{\text{ef}}}$$

Increased dielectric strength can be achieved in that at least one of the switches, advantageously the respective switch, at least of the device is based on silicon, in particular is a silicon switch. The respective switch is preferably based on silicon carbide, also referred to as “SiC” for short below. The respective switch is preferably a SiC switch, particularly preferably a SiC MOSFET. An increased dielectric strength can thus be achieved for the respective switch, so that the dielectric strength of the device is increased.

Embodiments are considered to be advantageous in which a fixed voltage is present at the third switch control connection and/or at the fourth switch control connection during operation. A simple and reliable limitation of the electrical voltage applied to the comparators can thus be achieved. In particular, a fixed voltage can be present at the third switch control connection relative to the first first switch connection, and/or a fixed voltage can be present at the fourth switch control connection relative to the first second switch connection. If the switches are configured as transistors or MOSFETs, this means in particular that the gate supply voltage of the third switch and/or the fourth switch can also be a fixed voltage relative to the respective source potential. The first-switch first connection thus represents the reference potential for the third-switch control connection, with the fixed, constant voltage compared to the first-switch first connection being present at the third-switch control connection during operation. Alternatively or additionally, the second switch first connection represents the reference potential for the fourth switch control connection, with the fixed, constant voltage being present at the fourth switch control connection compared to the second switch first connection during operation. For example, the fixed voltage is 15 V.

Embodiments are advantageous in which the device has a diode separate from the switches and thus dedicated for at least one of the switches of the device, advantageously for the respective switch of the device. The dedicated diode is preferably such that it provides a path of lower electrical resistance for the associated current of the associated switch. In contrast to the prior art, in which the so-called body diode intrinsically present in the switch is used for the respective switch to implement the associated flow path, a dedicated diode is used in the advantageous embodiment. It is thus possible, in particular in the case of SiC MOSFESTs whose body diodes have increased forward voltages, to provide a lower forward voltage for the respective flow path. As a result, the device can be operated with increased dielectric strength and consequently at increased operating voltages with low forward voltages and thus with increased efficiency.

Consequently, it is preferred if both switches are SiC MOSFETs and the device has a dedicated diode for the respective switch. A SiC MOSFET has opposite for example a Si-MOSFET has a higher dielectric strength of, for example, over 1000V, for example over 1200V. However, the body diode of a SiC MOSFET has an increased forward voltage of 4.2V, for example, compared to the body diode of a Si MOSFET. The increased forward voltage of the SiC MOSFET would lead to increased losses when current flows through the body diode of the SiC MOSFET. This is counteracted with the dedicated diode, which provides a lower electrical resistance than the body diode, so that the current flows via the dedicated diode instead of the body diode. Thus, with an increased electric strength, an increased efficiency is achieved at the same time.

The respective dedicated diode also means that no undesired current paths are formed via the corresponding body diode. Thus, the device is more precise and efficient.

It is preferred if at least one of the dedicated diodes, particularly preferably the respective dedicated diode, is a SiC diode, in particular a SiC Schottky diode. Thus, the withstand voltage of the dedicated diodes and consequently of the device is also increased.

Embodiments are particularly preferred in which the respective switch is a SiC MOSFET and the respective dedicated diode is a SiC diode, in particular a SiC Schottky diode. Thus, in particular, the dielectric strength is increased compared to a device with Si-MOSFETs.

Accordingly, it is preferred if the device has an associated dedicated diode for the first switch, which is also referred to below as the first diode. In a known manner, the first diode comprises a forward connection and a blocking connection, which are also referred to below as the first forward connection and the first blocking connection. In this case, the first first switch connection is electrically connected to the first forward connection and the first blocking connection is electrically connected to the second capacitor connection.

Accordingly, it is preferred if the device has an associated dedicated diode for the second switch, which is also referred to below as the second diode. That is, the device has the second diode separate from the switches and from the first diode. In a known manner, the second diode has a forward connection and a blocking connection, which are also referred to below as the second forward connection and second blocking connection. In this case, the first second switch connection is electrically connected to the second pass connection. Furthermore, the second blocking terminal is electrically connected to the first capacitor terminal. It is conceivable if the reverse connection of at least one of the diodes is electrically connected to the second switch connection of the associated source follower. This means that embodiments are conceivable in which the first blocking connection of the first diode is electrically connected to the second third switch connection and/or the second blocking connection of the second diode is electrically connected to the second fourth switch connection. In this way, the voltage present at the respectively associated diode of the device can be limited simply and effectively.

In principle it is also conceivable to connect the respective comparator to the switch.

The device advantageously has electrical connections via which the device is electrically connected to the inductive charging device. The device thus has a first device connection and a second device connection.

It is preferred here if the first capacitor connection is electrically connected to the first device connection and the second capacitor connection is electrically connected to the second device connection.

The inductive charging device interacts inductively with another inductive charging device in an associated energy transmission system for wireless energy transmission. For this purpose, at least one induction coil is provided in the respective induction charging device, with the induction coils of the induction charging devices interacting inductively. These induction coils are also known to those skilled in the art as primary coils and secondary coils. During operation, the primary coil generates a magnetic field which is received by the secondary coil.

The active adaptation of the capacitance and thus the impedance is advantageously used for active resonance adaptation between the primary coil and the secondary coil. In particular, in the event of an offset, the resonance condition is again met at the corresponding operating point, so that an increased, in particular maximum, power is transmitted.

The primary coil is advantageously part of a stationary inductive charging device and the secondary coil is part of a mobile inductive charging device.

It goes without saying that the inductive charging device can also have other components.

The inductive charging device can, for example, have a circuit for passively matching the impedance, which is also referred to below as a passive impedance circuit. The passive impedance circuit corresponds in particular to an “Impedance Matching Network” or “IMN” for short, which is also known to those skilled in the art. In this case, the passive impedance circuit advantageously corresponds to a fixed reactive power compensation. It is preferred here if the passive impedance circuit is connected between the induction coil and the device.

In principle, the energy transmission system can be used in any application for wireless energy transmission.

The energy transmission system can be used in particular for wireless energy transmission to charge a battery.

It is conceivable to charge the battery of a motor vehicle inductively and thus wirelessly. For this purpose, the mobile inductive charging device is advantageously provided on the motor vehicle and interacts with a stationary inductive charging device located outside of the motor vehicle.

It goes without saying that, in addition to the inductive charging device, such an energy transmission system also belongs to the scope of this invention.

Further important features and advantages of the invention result from the subclaims, from the drawings and from the associated description of the figures based on the drawings.

It goes without saying that the features mentioned above and those still to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, with the same reference numbers referring to identical or similar or functionally identical components.

• 1 eine stark vereinfachte, schaltplanartige Darstellung eines Energieübertragungssystems mit zumindest einer Induktionsladevorrichtung,
• 2 eine Schaltung einer Vorrichtung der Induktionsladevorrichtung zum aktiven Anpassen der Kapazität,
• 3 Diagramme zu verschiedenen Spannungs- und Stromverläufen durch die Vorrichtung,
• 4 die Vorrichtung in der in 3 mit I bezeichneten Durchströmungsphase,
• 5 die Vorrichtung in der in 3 mit II bezeichneten Durchströmungsphase,
• 6 die Vorrichtung in der in 3 mit III bezeichneten Durchströmungsphase,
• 7 die Vorrichtung in der in 3 mit IV bezeichneten Durchströmungsphase,
• 8 eine Schaltung der Induktionsladevorrichtung mit der Vorrichtung aus 3,
• 9 eine Schaltung der Induktionsladevorrichtung zur Spannungsnulldurchgangserkennung bei einem anderen Ausführungsbeispiel,
• 10 eine Schaltung der Induktionsladevorrichtung zur aktiven Resonanzanpassung mit Spannungsnulldurchgangserkennung bei einem weiteren Ausführungsbeispiel.

Show it, each schematically

• 1 a highly simplified, circuit diagram-like representation of an energy transmission system with at least one inductive charging device,
• 2 a circuit of a device of the induction charging device for actively adjusting the capacity,
• 3 Diagrams of different voltage and current curves through the device,
• 4 the device in the in 3 flow phase designated I,
• 5 the device in the in 3 flow phase designated II,
• 6 the device in the in 3 flow phase designated III,
• 7 the device in the in 3 flow phase designated IV,
• 8th a circuit of the inductive charging device with the device 3 ,
• 9 a circuit of the inductive charging device for voltage zero crossing detection in another embodiment,
• 10 a circuit of the inductive charging device for active resonance adjustment with voltage zero crossing detection in a further embodiment.

An inductive charging device 1 for wireless energy transmission, as for example in the 1 until 10 shown, is used in particular in an energy transmission system 2, which is exemplified in 1 is shown. The energy transmission system 2 comprises two such inductive charging devices 1, which interact inductively for wireless energy transmission. One of the inductive charging devices 1a serves to send the energy to the other inductive charging device 1b, which receives this energy. Accordingly, the inductive charging device 1a is also referred to below as the stationary inductive charging device 1a and the inductive charging device 1b is also referred to below as the mobile inductive charging device 1b. The respective inductive charging device 1 has at least one induction coil 3 for inductive interaction.

The stationary inductive charging device 1a is advantageously one that is connected to an electrical energy source 4 , for example a mains connection, or includes such an energy source 4 . The mobile inductive charging device 1b can be provided in a mobile application 5 in particular. Accordingly 1 the application 5 can be a motor vehicle 6 . The application 5 of the in 1 shown embodiment includes a battery 7, which is charged by means of wireless energy transmission.

At least one of the inductive charging devices 1 includes a device 8 for actively adjusting a capacity of the inductive charging device 1. In the in 1 In the exemplary embodiment shown, the respective inductive charging device 1 has such a device 8 .

The device 8 is controlled via a control circuit 9, which can have at least one driver IC (not shown) for this purpose.

At least one of the inductive charging devices 1 can also have a circuit 10 for passively matching an impedance of the inductive charging device 1 . The circuit 10 is also referred to below as a passive impedance circuit 10 . in the in 1 In the exemplary embodiment shown, the respective inductive charging device 1 has such an associated passive impedance circuit 10 . How 1 can be removed, the passive impedance circuit 10 is advantageously provided and connected in each case between the associated induction coil 3 and the associated device 8 .

at in 1 shown embodiment, the stationary inductive charging device 1a further comprises a power factor correction filter 11, also known as "PFC", and an inverter 45, which are provided between the energy source 4 and the device 8 are provided. In addition, the mobile inductive charging device 1b includes a rectifier 46 between the device 8 and the battery 7.

The 2 and 4 to 10 show the device 8. According to the 2 4 to 10, the device 8 has two electrical connections 12 for electrically connecting the device 8 in the associated inductive charging device 1, which are also referred to below as device connections 12. The device 8 thus has a first device connection 12a and a second device connection 12b. The device 8 also includes a capacitor arrangement 13 with at least one capacitor 14 , the capacitor arrangement 13 having a single capacitor 14 in the exemplary embodiments shown, so that the capacitor arrangement 13 corresponds to the capacitor 14 . The capacitor arrangement 13 includes two electrical connections 15, which are also referred to below as the first capacitor connection 15a and the second capacitor connection 15b. The first capacitor terminal 15a is electrically connected to the first device terminal 12a and the second capacitor terminal 15b is electrically connected to the second device terminal 12b. The device 8 further comprises two switches 16, the respective switch 16 being provided in an associated path of the device 8 which runs between the device terminals 12. The device 8 thus comprises a first switch 16a and a second switch 16b. The respective switch 16 has a first switch connection 17 and a second switch connection 18 between which an electric current can flow when the switch 16 is in the closed state. In addition, the respective switch 16 has a control connection 19 for switching the switch 16, which is coupled to the control circuit 9. The first switch 16a thus has a first switch connection 17a, also referred to below as the first first switch connection 17a, and a second switch connection 18a, also referred to below as the second first switch connection 18a. In addition, the first switch 16a has a control connection 19a, which is also referred to below as the first switch control connection 19a. Analogous to this, the second switch 16b has a first switch connection 17b, which is also referred to below as the first second switch connection 17b. The second switch 16b also has a second switch connection 18b, which is also referred to below as the second second switch connection 18b. Furthermore, the second switch 16b has a control connection 19b, which is also referred to below as the second switch control connection 19b.

In the exemplary embodiments shown and preferably, the respective switch 16 is in the form of a MOSFET 20 , with the first switch connection 17 corresponding to a source connection S, the second switch connection 18 corresponding to a drain connection D and the control connection 19 corresponding to a gate connection G of the MOSFET 20 . As in the 2 4 to 7 shown in dashed lines, the respective MOSFET 20 and thus switch 16 includes an intrinsic, integrated body diode B.

The respective second switch connection 18 of the switches 16 of the device 8 is electrically connected to an associated one of the capacitor connections 15 . That is, the second first switch terminal 18a is electrically connected to the first capacitor terminal 15a. In addition, the second second switch terminal 18b is electrically connected to the second capacitor terminal 15b. Thus, the second first switch terminal 18a is electrically connected to the first device terminal 12a. Furthermore, the second second switch terminal 18b is electrically connected to the second device terminal 12b. At the in the 2 12, 13 and 14 through 9, the first switch connections 17 of the first switch 16a and of the second switch 16b are electrically isolated from one another. That is, the first first switch terminal 17a is electrically isolated from the first second switch terminal 17b.

In the in the 2 11, 13, and 16 to 9, an associated, dedicated diode 22, which is therefore separate from the switches 16, is also provided for at least one of the switches 16 of the device. In the exemplary embodiment shown, an associated such diode 22 is provided for the respective switch 16 . The respective diode 22 here has a forward connection 23 and a blocking connection 24 , the forward connection 23 being connected to the first switch connection 17 of the associated switch 16 and the blocking connection 24 being connected to the corresponding capacitor connection 15 and thus device connection 12 . That is, the device 8 includes a first diode 22a having a first forward terminal 23a and a first blocking terminal 24a. At this time, the first pass terminal 23a is electrically connected to the first first switch terminal 17a. Furthermore, the first blocking terminal 24a is electrically connected to the second capacitor terminal 15b and thus to the second device terminal 12b. Furthermore, the device 8 comprises a second diode 22b which is separate from the first diode 22a and the switches 16 and has a second forward connection 23b and a second blocking connection 24b. The second pass terminal 23b is electrically connected to the first second switch terminal 17b and the second blocking terminal 24b is electrically connected to the first capacitor terminal 15a and thus the first device terminal 12a.

The respective diode 22 is preferably a SiC Schottky diode 25. The respective MOSFET 20 is preferably a SiC MOSFET 26. It is also preferred if the switches 16 and the diodes 22 are each configured identically are.

The respective switch 16, designed as a MOSFET 20, of the device 8 is activated by means of a control voltage UGS present between the associated gate connection G and source connection S (see 3 ) controlled by the control circuit 9. The first switch 16a is therefore controlled by means of a first control voltage UGSa, which is present between the gate connection G and the source connection S of the first switch 16a. Analogous to this, the second switch 16b is controlled by a second control voltage UGSb present between the gate connection G and the source connection S. In this way, the switches 16 can be switched individually and independently of one another.

The operation of the device 8 is based on the 3 until 7 explained as an example. 3 shows three diagrams 27, 28, 29. The time is plotted along the abscissa axis 30 of the respective diagram 27, 28, 29. A first diagram 27, which in the representation of 3 corresponds to the top diagram 27 shows a voltage profile and an electric current profile along the ordinate axis 31 . The total current flowing through the device 8 is shown with a solid line. Due to the voltage periodically present at the device connections 12, a periodic current flows through the device 8. In the first diagram 27, the voltage present at the capacitor arrangement 13 and thus at the capacitor 14 is also shown with a dashed line.

A second of the diagrams 28, which follows the first diagram 27, shows the corresponding time profile of the current flowing through the capacitor arrangement 13. The current flowing through the capacitor arrangement 13 is thus plotted in the second diagram along the ordinate axis 31 .

A third of Diagram 29, which appears in 3 corresponds to the bottom diagram 29 shows the time course of the control voltages UGS. The control voltage UGS is thus plotted along the ordinate axis 31 in the third diagram 29 . In the third diagram 29, the first control voltage UGSa present at the first switch 16a is shown with a solid line and the second control voltage UGSb present at the second switch 16b is shown with a dashed line.

Accordingly 3 ie the control circuit 9 applies a corresponding control voltage UGS to an associated switch 16 in the event of successive current zero crossings 32 in order to close this switch 16 . The closed state of the respective switch 16 is maintained for an associated time period t. The total current flowing through the device 8 therefore periodically successively passes through first current zero crossings 32a and second current zero crossings 32b. In this case, at the respective first current zero crossing 32a, the first control voltage UGSa is applied by the device 8 to the first-switch control connection 19a, so that the first switch 16a is closed for a first time period ta. In contrast, the second control voltage UGSb is applied to the second switch control connection 19b at the respective second current zero crossing, so that the second switch 16b is closed for a second time duration tb. Thus, when flowing through the device 8, there are a total of four flow variants that are carried out in a targeted manner. These flow variants are in the 4 until 7 shown, where the 4 a first flow variant I, the 5 a second flow variant II, the 6 a third flow variant III and the 7 shows a fourth flow variant IV. In the Operation of the device 8 in the exemplary embodiment shown results in the 3 shown sequence of flow variants I, II, III, IV, which are repeated periodically. Thus, the first flow variant I is followed by the second flow variant II, then again the first flow variant I, then the third flow variant III, then the fourth flow variant IV and then the third flow variant III, this being repeated periodically.

As in particular diagram 29 in 3 can be seen, the respective control voltage UGS has a switch-on delay, which is shown as extremely long in Diagram 3 for a better overview. This means that a time corresponding to the switch-on delay elapses in order to reach the control voltage UGS required for closing the respective switch 16 . How 3 can also be seen that the respective switch 16 designed as a MOSFET 20 contains the control signal UGS at the associated current zero crossing 32, but actually only takes over the current conduction through the device 8 in the following voltage zero crossing 43, since when the voltage zero crossing is reached there is no longer any voltage across the associated dedicated Diode 22 is present and it becomes conductive.

An active adaptation of the capacitance and thus the impedance of the device 8 takes place by changing the respective time period t and/or the respective switch-on angle. In this case, the first time period ta and the second time period tb preferably correspond to one another.

In 3 it is assumed that at the beginning of the shown flow through the device 8 there is a first current zero crossing 32a followed by a positive current. In this case, the electrical voltage across the capacitor arrangement 13 is negative, with the capacitor arrangement 13 being discharged by the positive current. At the first current zero crossing 32a, the first control voltage UGSa is applied with the switch-on delay and for the first period of time ta. The time period ta begins, as described above, when the voltage zero crossing 43 following the first current zero crossing 32a is reached. The closed state of the first switch 16a is therefore reached when a threshold value of the first control voltage UGSa is reached, with the capacitor arrangement 13 being completely discharged when this threshold value is reached and the first switch 16a is closed. The first flow variant I is present until the first switch 16a is closed. Accordingly 4 In the first flow variant I, the current flows through the capacitor arrangement 13.

If the first switch 16a is closed, the second flow variant II is present. Accordingly 5 in the second flow variant II, the current flows from the first device connection 12a via the first switch 16a and the first diode 22a to the second device switch 12b. Flowing through the device 8 via the second switch 16b is not possible due to the second diode 23b and the open state of the second switch 16b.

After the first period of time ta has elapsed and thus after the first control voltage UGSa has been switched off and the first switch 16a has been opened, the following occurs accordingly 3 again the first through-flow variant I, which in 4 is shown. This means that due to the open state of both switches 16 and the arrangement of the diodes 22, the electric current charges the capacitor arrangement 13, so that the voltage present at the capacitor arrangement 13 reaches a maximum when the second current zero crossing 32b is reached. Here, as explained, the second control voltage UGSb is applied to the second switch 16b, the capacitor arrangement according to FIG 6 shown third flow variant III is discharged. According to the 3 and 6 the condenser arrangement 13 in the third through-flow variant III flows in the opposite direction to the first through-flow variant I. This means that the device 8 flows through from the second device connection 12b via the capacitor arrangement 13 to the first capacitor connection 12a. If the threshold value of the second control voltage UGSb for closing the second switch 16b is reached, the fourth flow variant IV takes place.

Accordingly 7 and 3 in the fourth flow variant IV, the second switch 16b is closed, so that the electric current flows from the second device connection 12b via the second switch 16b and the second diode 22b to the first switch connection 12a. Flow through the first switch 16a is prevented due to the open state of the first switch 16a and the first diode 22a. After the second period of time tb has elapsed, the device 8 becomes corresponding 3 flows through according to the third flow variant III, which in 6 is shown.

The flow variants I, II, III, IV described are repeated periodically during operation.

To detect the successive voltage zero crossings 43 of the device 8, the device has a respective associated comparator 36, which only in the 8th until 10 is shown. That is, to detect first voltage zero crossings 43a, a first Comparator 36a and to detect second voltage zero crossings 43b, a second comparator 36b is used, the first voltage zero crossings 43a and the second voltage zero crossings 43b, such as 3 can be taken alternately. The respective comparator 36 has two comparator terminals 37, 38 serving as inputs and one output terminal 21. The comparator output terminals 21a, 21b are provided with an only in 1 shown device 44 of the inductive charging device 1 coupled. The device 44 is designed in such a way that it recognizes the voltage zero crossings 43 through the device 8 by means of the comparators 36a, 36b. The device 44 is also referred to below as a recognition device 44 . The recognition device 44 is in particular an evaluation circuit. Thus, the first comparator 36a has a first first comparator connection 37a and a second first comparator connection 38a as well as a first comparator output connection 21a. In addition, the second comparator 36b has a first second comparator connection 37b, a second second comparator connection 38b and a second comparator output connection 21b. In addition, the inductive charging device 1 has an associated voltage limiter 42 for the respective comparator 36 and the associated switch 16a, 16b of the device 8, which is designed such that it limits the voltage present at the comparator terminals 37, 38 of the associated comparator 36. A first voltage limiter 42a is thus connected between the first switch 16a and the first comparator 36a and a second voltage limiter 42b is connected between the second switch 16b and the second comparator 36b.

in 1 shown embodiment, the detection device 44 and the control circuit 9 are separate components of the inductive charging device 1. It is also conceivable to integrate the detection device 44 and the control circuit 9 in a common device of the inductive charging device 1, not shown.

Voltage zero crossing detection can be used for monitoring and/or control functions. The voltage zero crossing detection in the control circuit 9 can also be taken into account. In this case, the detection device 44 is coupled to the control circuit 9 (not shown), so that the control circuit 9 can take the voltage zero crossings 43 into account.

In the exemplary embodiments shown, the voltage limiters 42 are of identical design. In this case, the respective voltage limiter 42 is designed in the manner of a source follower of the associated switch 16 of the device 8 . The respective voltage limiter 42 has a switch 16 and a resistor 33 for this purpose. In the exemplary embodiments shown, the first voltage limiter 42a thus has a third switch 16c and a first resistor 33a. In addition, the second voltage limiter 42b has a fourth switch 16d and a second resistor 33b. The third switch 16c and the fourth switch 16d have, like the switches 16a, 16b of the device 8, a first switch connection 17 and a second switch connection 18 as well as a control connection 19. That is, the third switch 16c has a first third switch port 17c, a second third switch port 18c, and a third switch control port 19c. In addition, the fourth switch 16d has a first fourth-switch connection 17d, a second fourth-switch connection 18d and a fourth-switch control connection 19d. The respective resistor 33 has two resistor terminals 34, 35. That is, the first resistor 33a has a first first-resistance terminal 34a and a second first-resistance terminal 35a. In addition, the second resistor 33b has a first second resistor connection 34b and a second second resistor connection 35b. Like the 8th until 10 can be removed, the first first switch connection 17a is electrically connected to the first first resistance connection 34a and the first third switch connection 17c is electrically connected to the second first resistance connection 35a. Furthermore, the first second switch connection 17b is electrically connected to the first second resistance connection 34b and the first fourth switch connection 17d is electrically connected to the second second resistance connection 35b. In addition, the first first resistance connection 34a is electrically connected to the first first comparator connection 37a and the second first resistance connection 35a is electrically connected to the second first comparator connection 38a. Furthermore, the first second resistance terminal 34b is electrically connected to the first second comparator terminal 37b and the second second resistance terminal 35b is electrically connected to the second second comparator terminal 38b. In this case, the third switch 16c and the fourth switch 16d, like the first switch 16a and the second switch 16b, are advantageously each designed as a MOSFET 20, preferably as a SiC-MOSFET 26, with the respective first switch connection 17 in turn being assigned a source connection S, the respective second switch connection 18 corresponds to a drain connection D and the respective control connection 19 corresponds to a gate connection G of the MOSFET 20 . The third switch 16c and the first resistor 33a act together as limiters of the voltage present between the comparator terminals 37a, 38a of the first comparator 36a in the manner of a source follower of the first switch 16a.

Analogous to this, the fourth switch 16d and the second resistor 33b act together as limiters of the voltage present between the comparator terminals 37b, 38b of the second comparator 36b in the manner of a source follower of the second switch 16b. The voltage present at the respective comparator 36 is thus limited. This is done by appropriately designing the third switch 16c and the first resistor 33a and the fourth switch 16d and the second resistor 33b. The voltage present at the respective comparator 36 corresponds to the voltage present between the first switch connection 17 and the second switch connection 18 of the associated switch 16a, 16b up to said limit and above the limit to the limit. So if the limitation is 15 V, for example, the voltage present between the first first comparator connection 37a and the second first comparator connection 38a corresponds to this voltage for voltages between the first first switch connection 17a and the second first switch connection 18a of up to 15 V and for voltages of more than 15 V to the limitation , i.e. 15 V. Analogously to this, the voltage present between the first second comparator connection 37b and the second second comparator connection 38b corresponds to this voltage for voltages between the first second switch connection 17b and the second second switch connection 18b of up to 15 V and for voltages of more than 15 V to the limit, ie 15 V. In this way, a precise and simple detection of the voltage zero crossings 32 by the respective switch 16a, 16b of the device 8 is achieved.

How 9 can be removed, at least one of the comparators 36, preferably the respective comparator 36, is advantageously to be electrically isolated from the detection device 44. 9 shows using the example of the second comparator 36b that for this purpose between the output terminal 21 and the in 9 detection device 44 not shown, a logic isolator 40, in particular an optocoupler 41, can be arranged.

As in the 8th and 9 indicated, during operation a fixed voltage or gate supply voltage is present at the third switch control connection 19c relative to the first first switch connection 17a. In addition, during operation, a fixed voltage or gate supply voltage is present at the fourth-switch control connection 19d relative to the second first-switch connection 17b. For example, the fixed voltage is 15 V.

10 shows another embodiment of the device 8, which differs from that in FIGS 2 4 to 9 in particular in that the switches 16a, 16b of the device 8 are arranged in series in a common current path of the device 8 and in reverse series with one another. In this exemplary embodiment, the first primary switch connection 17a and the first secondary switch connection 17b are electrically connected to one another. In contrast to the embodiments of 2 and 4 to 9, no dedicated, additional diodes 22 are provided in this exemplary embodiment. In this case, the body diode B of the second switch 16b acts for the first switch 16a and the body diode B of the first switch 16a acts for the second switch 16b instead of in the exemplary embodiments of FIG 2 and dedicated diodes 22 shown in FIGS. 4 to 9. In this exemplary embodiment, the first third switch connection 17c and the first fourth switch connection 17d are also electrically connected via the resistors 33 to one another and to the first first switch connection 17a and consequently also to the first second switch connection 17b.

With the inductive charging device 1 according to the invention, it is possible in particular to detect the voltage zero crossings 43 more precisely.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited 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.

Patent Literature Cited

• EP 3365958 B1 [0003]

Claims (13)

Inductive charging device (1) for wireless energy transmission, in particular for charging a battery (7) in a motor vehicle (6), with a device (8) for actively adjusting a capacity, wherein - the device (8) has a capacitor arrangement (13) comprising at least one capacitor (14) and having a first capacitor connection (15a) and a second capacitor connection (15b), - the device (8) has a first switch (16a), which has a first first switch connection (17a), a second first switch connection (18a) and a first switch control connection (19a), - the device (8) has a second switch (16b) which has a first second switch connection (17b), a second second switch connection (18b) and a second switch control connection (19b), - the second first switch connection (18a) is electrically connected to the first capacitor connection (15a) and the second second switch connection (18b) is electrically connected to the second capacitor connection (15b), - the inductive charging device (1) for the first switch (16a) has a first comparator (36a) with a first first comparator connection (37a) and a second first comparator connection (38a) and a first comparator output connection (21a), - the inductive charging device (1) for the second switch (16b) has a second comparator (36b) with a first second comparator connection (37b) and a second second comparator connection (38b) and a second comparator output connection (21b), - an associated first voltage limiter (42a) is connected between the first switch (16a) and the first comparator (36a), which limits the voltage present between the first first comparator connection (37a) and the second first comparator connection (38a), - an associated second voltage limiter (42b) is connected between the second switch (16b) and the second comparator (36b), which limits the voltage present between the first second comparator connection (37b) and the second second comparator connection (38b), the inductive charging device (1) has a detection device (44) which is coupled to the comparator output connections (21a, 21b) and is designed in such a way that it uses the comparators (36a, 36b) to detect voltage zero crossings (43) through the switches (16a, 16b) and/or the capacitor arrangement (13). inductive charging device claim 1 , characterized in that - that the first voltage limiter (42a) has a third switch (16c) which has a first third switch connection (17c), a second third switch connection (18c) and a third switch control connection (19c), - that the first voltage limiter ( 42a) has a first resistor (33a) with a first first resistor connection (34a) and a second first resistor connection (35a), - that the second voltage limiter (42b) has a fourth switch (16d) which has a first fourth switch connection (17d), a second Fourth switch connection (18d) and a fourth switch control connection (19d), - that the second voltage limiter (42b) has a second resistor (33b) with a first second resistor connection (34b) and a second second resistor connection (35b), - that the first first switch connection ( 17a) is electrically connected to the first first resistance connection (34a) and the first third switch connection (17c) is electrically connected to the second first resistance connection (35a), - that the first second switch connection (17b) is electrically connected to the first second resistance connection (34b) and the first fourth switch connection (17d ) is electrically connected to the second second resistance connection (35b), - that the first first resistance connection (34a) is electrically connected to the first first comparator connection (37a) and the second first resistance connection (35a) is electrically connected to the second first comparator connection (38a), - that the first The second resistor terminal (34b) is electrically connected to the first second comparator terminal (37b) and the second second resistor terminal (35b) is electrically connected to the second second comparator terminal (38b). inductive charging device claim 1 or 2 , characterized in that the output terminal (21) of at least one of the comparators (36) is electrically isolated from the detection device (44). inductive charging device claim 3 , characterized in that at least one of the output terminals (21) is coupled to the detection device (44) via a logic isolator (40), in particular an optocoupler (41). Inductive charging device according to one of claims 2 until 4 , characterized in that - that a fixed voltage is present at the third switch control connection (19c) relative to the first first switch connection (17a), and/or - that a fixed voltage is present at the fourth switch control connection (19d) relative to the second first switch connection (17b). Inductive charging device according to one of Claims 1 until 5 , characterized in that - the inductive charging device (1) has a control circuit (9) which is coupled to the first switch control connection (19a) and the second switch control connection (19b), - that the control circuit (9) is designed in such a way that it actively adjusts the capacitance of the device (8) by closing and opening the first switch (16a) and the second switch (16b). inductive charging device claim 6 , characterized in that the control circuit (9) is designed in such a way that it adjusts the capacitance of the device (8) by the following: - at a first current zero crossing (32a) through the device (8), a first control signal (UGSa) is sent to the First switch control connection (19a) is applied, so that the first switch (16a) is closed for a first period of time (ta), - at a second current zero crossing (32b) through the device (8) following the first current zero crossing (32a), a second Control signal (UGSb) applied to the second switch control terminal (19b), so that the second switch (16b) is closed for a second period of time (tb). Inductive charging device according to one of Claims 1 until 7 , characterized in that - that at least one of the switches (16) is designed as a MOSFET (20), - that the first switch connection (17) has a source connection (S), the second switch connection (18) has a drain connection (D) and the control connection (19) corresponds to a gate terminal (G) of the MOSFET (20). Inductive charging device according to claim one of Claims 1 until 8th , characterized in that - that the device (8) has a first diode (22a) which is separate from the switches (16), - that the first diode (22a) has a first forward terminal (23a) and a first blocking terminal (24a) - that the first first switch connection (17a) is electrically connected to the first forward connection (23a) and the first blocking connection (24a) is electrically connected to the second capacitor connection (15b), - that the first blocking connection (24a) is electrically connected to the second third switch connection ( 18c) is connected. inductive charging device claim 9 , characterized in that - the first primary switch connection (17a) and the first two-switch connection (17b) are electrically isolated from one another, - the second primary switch connection (18a) and/or the first diode blocking connection 24a is electrically connected to the second third-switch connection (18c), and/or - that the second second switch connection (18b) and/or the second diode blocking connection 24b is electrically connected to the second fourth switch connection (18d). Inductive charging device according to one of Claims 1 until 10 , characterized in that - that the device (8) has a second diode (22b) which is separate from the switches (16) and the first diode (22a), - that the second diode (22b) has a second forward terminal (23b) and a second blocking terminal (24b), - the first second switch terminal (17b) being electrically connected to the second conducting terminal (23b) and the second blocking terminal (24b) being electrically connected to the first capacitor terminal (15a), - the second blocking terminal (24b) is electrically connected to the second fourth switch terminal (18d). Energy transmission system (2), with a stationary inductive charging device (1a) and a mobile inductive charging device (1b), which interact inductively for wireless energy transmission from the stationary inductive charging device (1a) to the mobile inductive charging device (1b), at least one of the inductive charging device (1) according to one of Claims 1 until 11 is trained. energy transmission system claim 12 , characterized in that - that the mobile inductive charging device (1b) is provided in a motor vehicle (6), the motor vehicle (6) further comprising a battery (7) with which the mobile inductive charging device (1b) is connected, - that the stationary Inductive charging device (1a) is arranged outside of the motor vehicle (6) and, in operation, interacts with the mobile inductive charging device (1b) for wireless charging of the battery (7).

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