Wireless power transfer device and system

Abstract

The invention relates to a wireless power transfer (WPT) device configured to be mounted in an electric vehicle for charging a traction battery of the electric vehicle. The WPT device comprises a WPT receiver coil, a rectifier and at least two safety switching units coupled in parallel rectifier switching units of the full bridge rectifier. A control unit controls the at least two safety switching units to be open during a charging operation of the WPT device and to be closed at least during powering up of the WPT receiver coil and / or in case of a damage or malfunction of the WPT device or any element thereof.

Description

[0001] 28.07.2025

[0002] 1

[0003] Wireless power transfer device and system

[0004] The present invention relates to a wireless power transfer (WPT) device and a WPT system.

[0005] WPT using magnetic resonance is the technology which could set humans free from the annoying wires. In fact, the WPT adopts the same basic theory which has already been developed for at least 30 years with the term inductive power transfer. WPT technology has been developing rapidly in recent years. At kilowatts power level, the transfer distance increases from several millimeters to several hundred millimeters with a grid to load efficiency above 90%. The advances make the WPT very attractive to electric vehicle (EV) charging applications in both stationary and dynamic charging scenarios. By introducing WPT in EVs, the obstacles of charging time, range, and cost can be easily mitigated, and battery technology is not as relevant in the EV market.

[0006] Conventionally, in power conversion, when AC is converted to low voltage DC, or AC from one frequency to another, the AC is usually rectified and smoothed to obtain a fixed voltage at fixed frequency. Once this is accomplished, the power is then routed to an inverter to obtain the final output with variable voltage and variable frequency.

[0007] EP 3694 079 A1 discloses a WPT system for an electrical vehicle (EV), the WPT system comprising a ground assembly (GA) including a transmitter coil and a vehicle assembly (VA) including a receiver coil magnetically coupled to the GA transmitter coil for inductive power transfer from the GA to the VA in order to charge a traction battery of the EV.

[0008] The VA, which represents a WPT device, comprises a rectifier for converting the electric AC power coupled into its receiver coil into electric DC power, which is typically implemented as full bridge rectifier. There may be malfunctions or failures in the VA or the GA, which may lead to damages of the electronics of the VA or GA. 28.07.2025

[0009] 2

[0010] It is an object of the present invention to provide a safety mechanism to prevent such damages, particularly of the VA.

[0011] In a first aspect of the present invention a WPT device is presented that is configured to be mounted in an electric vehicle for charging a traction battery of the electric vehicle, the WPT device comprising: a WPT receiver coil configured to inductively receive electric AC power from a WPT transmitter coil; a rectifier configured to convert the electric AC power into electric DC power, the rectifier comprising: a pair of input terminals configured to receive the electric AC power; a pair of output terminals configured to output the electric DC power; four rectifier switching units forming a full bridge rectifier; and at least two safety switching units, wherein a first safety switching unit is coupled in parallel to a first rectifier switching unit of the full bridge rectifier that is coupled between a first input terminal and a first output terminal and a second safety switching unit is coupled in parallel to a third rectifier switching unit of the full bridge rectifier that is coupled between a second input terminal and the first output terminal; and a control unit configured to control the at least two safety switching units to be open during a charging operation of the WPT device and to be closed at least during powering up of the WPT receiver coil and / or in case of a damage or malfunction of the WPT device or any element thereof.

[0012] In a further aspect of the present invention a WPT system is presented comprising a WPT device as disclosed herein, and a traction battery coupled to the WPT device.

[0013] Preferred embodiments of the invention are defined in the dependent claims. It shall be understood that the claimed WPT system has similar and / or identical preferred embodiments as the claimed WPT device, in particular as defined in the dependent claims and as disclosed herein. 28.07.2025

[0014] 3

[0015] The present invention is based on the idea to make use of additional safety switching units, at least within the rectifier of the WPT device that is configured to operate as VA, and to control these additional safety switching units such that the WPT receiver coil is shorted during a malfunction in the WPT device or even in a second WPT device that is configured to operate as GA. During a charging operation the additional safety switching units in the rectifier are controlled to be open so that they do not influence the desired (normal) operation of the rectifier.

[0016] In this context it shall be noted that the expression “safety switching unit” shall be understood broadly as additional switching unit provided in addition to the “rectifier switching units” with the intention to contribute to the desired safety of the operation of the WPT device, i.e. , the terms “safety” in the expression “safety switching unit” and “rectifier” in the expression “rectifier switching unit” are mainly used to distinguish the two different types of switching units rather than restricting them to any particular type of switching units.

[0017] In a preferred embodiment the first and second safety switching units are normally closed safety switching units. This ensures their desired function of always shortening the WPT receiver coil except during a charging operation. Alternatively or in addition, the control unit may be configured in an embodiment to control the at least two safety switching units to be open only during the charging operation of the WPT device and to be closed at all other times.

[0018] In another embodiment the WPT device further comprises a third safety switching unit coupled to the second output terminal of the rectifier, wherein the control unit is configured to control the third safety switching unit to be closed during a charging operation of the WPT device and to be open at least during powering up of the WPT receiver coil and / or in case of a damage or malfunction of the WPT device or any element thereof. The addition of the third safety switching unit provides an extra safety mechanism for protecting the traction battery and other electronics of the WPT device. It is closed during the charging operation, but open during other times to avoid an undesired and possibly damaging flow of current to the traction battery or other 28.07.2025

[0019] 4 electronics while the WPT receiver coil is powered up or if there is any damage or malfunction in the WPT device or the second WPT device.

[0020] The WPT device may further comprise a capacitor and / or a filter unit coupled to the output terminals of the rectifier; battery terminals at the output of the capacitor or the filter unit configured for coupling the traction battery to the WPT device; and a fourth safety switching unit coupled to a first battery terminal and / or a fifth safety switching unit coupled to a second battery terminal, wherein the control unit is configured to control the fourth and / or fifth safety switching units to be closed during a charging operation of the WPT device and to be open at least during powering up of the WPT receiver coil and / or in case of a damage or malfunction of the WPT device or any element thereof. The fourth and fifth switching units provide additional safety for protecting the traction battery.

[0021] Preferably, the third, fourth and fifth safety switching units are normally open safety switching units. This ensures their desired function of always avoiding current flow into the traction battery except during a charging operation. Alternatively or in addition, the control unit may be configured to control the third, fourth and fifth safety switching units to be closed only during the charging operation of the WPT device and to be open at all other times.

[0022] The fourth and fifth safety switching units may be part of the WPT device. In another embodiment, they may be part of the traction battery or the EV rather than part of the WPT device. Even in such an embodiment, the control unit of the WPT device may be configured to provide a control signal to control one or more safety switching units coupled to one or more input terminals of the traction battery to be closed during a charging operation of the WPT device and to be open at least during powering up of the WPT receiver coil and / or in case of a damage or malfunction of the WPT device or any element thereof.

[0023] In an embodiment, the control unit is configured to control the safety switching units to change their state simultaneously. In another embodiment, they may be controlled to 28.07.2025

[0024] 5 change their state independently, which provides more flexibility for the control and may provide more safety if, e.g., one or more switching units may malfunction.

[0025] The WPT device may further comprise detection means configured to detect one or more of: if there is a damage in the first and / or third rectifier switching unit, if electric AC power is not or insufficiently available at the first and / or third rectifier switching unit, in particular if there is insufficient voltage at one or more of the rectifier switching units to switch them on, if there is any malfunction in the WPT device or in a second WPT device comprising a WPT transmitter coil configured to inductively couple electric AC power into the WPT receiver coil of the WPT device, and if there is an overvoltage in a capacitor coupled between the output terminals of the rectifier.

[0026] A further malfunction may, e.g., be an overtemperature.

[0027] The detection means may comprise electronic circuitry configured to measure output voltage of the WPT device and / or the rectifier and / or to detect a malfunction in the WPT device, in particular the rectifier. A malfunction or damage of the WPT device (the VA) may be communicated to the second WPT device (GA) so that the second WPT device can make use of this information. The VA may detect a malfunction in the VA side or indirectly in the GA side. In such a situation, the VA may send corresponding information, e.g. a warning or error information, to the GA. As soon as the GA receives this information, it may stop transferring power, while the VA may switch into its safety state.

[0028] There are different options for implementing the different switching units. In an embodiment, the rectifier switching units are semiconductor switches. In another embodiment, the safety switching units are relay units, in particular electromagnetically controlled switches. 28.07.2025

[0029] 6

[0030] The WPT system according to the present invention at least comprises a WPT device as disclosed herein, and a traction battery coupled to the WPT device. In an embodiment, the WPT system may further comprise a second WPT device (a GA) comprising a WPT transmitter coil configured to inductively couple electric AC power into the WPT receiver coil of the WPT device (the VA).

[0031] The foregoing paragraphs have been provided by way of general introduction and are not intended to limit the scope of the following claims. A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

[0032] Fig. 1 shows a schematic diagram of the general layout of a WPT system for an EV. Fig. 2 shows a circuit diagram of the typical circuitry of WPT device.

[0033] Fig. 3 shows a circuit diagram of the typical circuitry of WPT device including active protection means.

[0034] Fig. 4 shows a diagram of drain current versus drain-to-source voltage of a MOSFET.

[0035] Fig. 5 shows a circuit diagram of a first embodiment of a WPT device according to the present invention.

[0036] Fig. 6 shows a circuit diagram of a second embodiment of a WPT device according to the present invention in a safety state.

[0037] Fig. 7 shows the circuit diagram of the second embodiment of a WPT device according to the present invention in a normal operation state.

[0038] Fig. 8 shows a circuit diagram of a third embodiment of a WPT device according to the present invention.

[0039] Fig. 9 shows a flowchart of the different states for the second embodiment of the WPT device shown in Figs. 6 and 7.

[0040] Fig. 10 shows a circuit diagram of a fourth embodiment of a WPT device according to the present invention.

[0041] Fig. 1 shows a schematic diagram of a generally known WPT system 100 for an EV

[0042] 120, as, e.g., disclosed in EP 3694079 A1. In this WPT system 100 the basic functional 28.07.2025

[0043] 7 blocks for inductive charging are shared between a ground assembly (GA) 101 and a vehicle assembly (VA) 102, each of them representing a separate WPT device of the WPT system 100. The WPT system 100 comprises an inductive charging coil assembly 112 comprising a transmitter coil (also called transmitting coil or GA coil) 107 located at the GA side and a receiver coil (also called receiving coil or VA coil) 108 located at the vehicle side.

[0044] The GA 101 of the WPT system 100 comprises an AC / DC converter 104 with power factor correction (PFC) that converts the single or three phase power source 103 to a regulated DC power source. The GA 101 further comprises a DC to high frequency (HF) AC converter 105 that generates a square wave voltage with nearly constant frequency and duty cycle. A primary compensation circuit 106, which is a passive circuit network, compensates the transmitter coil inductance in order to reduce the amount of reactive power delivered by the DC to HF AC converter 105. The transmitter coil 107 transmit power through a magnetic field and adds isolation between the AC power inlet and the vehicle HV battery 111.

[0045] The VA 102 comprises a receiver coil 108 that picks up power through the magnetic field and adds isolation between the AC power inlet and the vehicle HV battery 111. A secondary compensation circuit 109, which is a passive circuit network, compensates the receiving coil inductance in order to maximize the transferred power at electrical resonance. The VA 102 comprises an (active or passive) AC / DC rectifier 110 that converts high frequency AC current to DC current to charge the vehicle HV battery. A DC / DC battery charger (that may or may not include battery charging algorithms / charging strategy) may be provided. Finally, the VA 102 comprises the high voltage battery 111 (also called traction battery).

[0046] The architecture of the VA may differ depending upon many criteria, including network compensation or charging / discharging strategy. The charging of the high voltage battery 111 can potentially be handled by both assemblies, the GA 101 and the VA 102 of the WPT system 100, which design can determine an optimal WPT architecture. 28.07.2025

[0047] 8

[0048] Fig. 2 shows a circuit diagram of the typical circuitry of WPT device 200 configured to operate as VA, e.g. as the VA 102 of the WPT system shown in Fig. 1 . The receiving coil 201 and the passive electronics 202 that mainly operate as compensation circuitry maximize the received transferred power of the VA 200. A rectifier 203 implemented as a full bridge 203 formed by switches (herein also called rectifier switches), e.g. the MOSFETs Q1 , Q2, Q3, Q4, is able to rectify the received transferred power from the GA thus increasing the efficiency of the WPT system. A DC link capacitor 204 and passive electronics 205, such as an electromagnetic interference (EMI) filter, are coupled between the full bridge 203 and the battery 206.

[0049] Assuming both WPT devices (GA and VA) are supplied separately, safety mechanisms (SM) should be provided in order to protect the GA and VA in case of an error. Fig. 3 shows a circuit diagram of a WPT device 300 configured to operate as VA including means for an active protection. Both switches Q1 and Q3 of the rectifier are fully activated while switches Q2 and Q4 are kept completely off (error state). This state protects the whole electronics if an error occurred (e.g., a disconnection of the battery line, etc.). This state may, as well, be used during the startup of the WPT system to avoid uncontrolled power to be transferred to the battery until the WPT system is stabilized.

[0050] Due to a possible malfunction in the GA and / or a failure in the VA where the voltage to control the MOSFETs Q1-Q4 may not be enough (less than 10-15 Volt), and therefore the MOSFETs Q1 and Q3 may not be activated with its lowest conduction resistance (RDSON), i.e. , the nominal value of the MOSFET when it is completely switched on. This may lead to a fatal increase of the temperature in these MOSFETs due to their high power consumption (lrms2*RDSON) since the resistance with be increased, possibly leading to a destruction of the electronics. Fig. 4 shows a diagram of drain current (IDS) versus drain-to-source voltage (VDS) of a MOSFET for different VGS (gate-to-source). It can be seen that at lower VGS voltage at the MOSFET leads to an increase in the dissipated power at the MOSFET and to a movement from the linear zone to the saturation zone where higher conduction losses are expected. IGBT (bipolar junction 28.07.2025

[0051] 9 transistor) and BJT (bipolar junction transistor) transistors may be used instead of MOSFETs, but MOSFETs transistors may be more suitable for this kind of applications.

[0052] The known circuitries described above and shown in Figs. 2 and 3 thus have the following disadvantages. There is no protection against damages, i.e. , the GA persists with the power transfer while the VA cannot assure a correct control of the MOSFETs of the rectifier, in particular the MOSFETs Q1 and Q3. A protection may be necessary under different scenarios including a load dump event, damaged electronics, etc. The present invention thus aims to increase the security of the whole electronics.

[0053] Fig. 5 shows a circuit diagram of a first embodiment of a WPT device 400 according to the present invention that is configured to operate as VA, e.g. the VA 102 of the WPT system shown in Fig. 1 . In addition to the elements of the circuitry shown in Fig. 3 the WPT device 400 provides means that leads to an extra safety state during a malfunction or during the start-up of the VA by means of a two safety switching units S1 , S2, e.g. two relay units (such as electromagnetically controlled switches or a single electromagnetically controlled relay). The embodiment of the WPT device 400 comprises a receiving coil 401 , passive electronics 402, a rectifier 403, a DC link capacitor 404, and passive electronics 405, to which the battery 406 is connected.

[0054] The rectifier 403 comprises a pair of input terminals 403a, 403b configured to receive the electric AC power from the compensation unit 402, a pair of output terminals 403c, 403d configured to output the electric DC power to the DC link capacitor 404, four rectifier switching units Q1 , Q2, Q3, Q4 forming a full bridge rectifier, and at least two safety switching units S1 , S2. The first safety switching unit S1 is coupled in parallel to a first rectifier switching unit, in the embodiment shown in Fig. 5 the rectifier switching unit Q1 , that is coupled between a first input terminal 403a and a first output terminal 403d. The second safety switching unit S2 is coupled in parallel to a third rectifier switching unit, in the embodiment shown in Fig. 5 the rectifier switching unit Q3, that is coupled between a second input terminal 403b and the first output terminal 403d. 28.07.2025

[0055] 10

[0056] A control unit 407 is provided that is configured to control the at least two safety switching units S1 , S2 to be open during a charging operation of the WPT device 400 and to be closed at least during powering up of the WPT receiver coil 401 and / or in case of a damage or malfunction of the WPT device 401 or any element thereof, or optionally in case of a damage or malfunction of another WPT device that is configured to operate as GA. Preferably, the control unit 407 is configured to control the rectifier switching units Q1-Q4 as well. The control may be provided such that the two safety switching units S1 , S2 are controlled simultaneously or individually. Similarly, the rectifier switching units Q1-Q4 may be controlled simultaneously or individually. Preferably, the safety switching units S1 , S2 and the rectifier switching units Q1-Q4 are controlled simultaneously but may also be controlled individually.

[0057] The safety switching units S1 , S2 may be a normally closed relay units that are shorted in parallel to the low side MOSFETs Q1 , Q3. In another embodiment, the safety switching units S1 , S2 may be arranged in parallel to the high side MOSFETs Q2, Q4. The safety switching units S1 , S2 may be implemented by a single relay that has two operating contact terminals. Fig. 6 shows a circuit diagram of a second embodiment of a WPT device 500 according to the present invention. In this embodiment, a third safety switching unit S3, e.g. a third relay unit, is provided that is coupled to the second output terminal 403c of the rectifier 403, in particular between the second output terminal 403c and the positive input terminal 406a of the battery 406 or, as shown in Fig. 6, an input terminal 405a of the EMI filter 405. The control unit 407 is configured to control the third safety switching unit S3 to be closed during a charging operation of the WPT device and to be open at least during powering up of the WPT receiver coil 401 and / or in case of a damage or malfunction of the WPT device 400 or any element thereof, or optionally in case of a damage or malfunction of another WPT device that is configured to operate as GA. In an embodiment, the third safety switching unit S3 may be part of a single relay that has three pairs of operating contact terminals representing the three safety switching units S1 , S2, S3, i.e. , two operating contact terminals per safety switching unit. With this third safety switching unit S3, which may be implemented as normally open relay unit, an extra protection is achieved where a cross-conduction through Q2 and S1 (or Q4 and S2) is avoided. 28.07.2025

[0058] 11

[0059] Fig. 6 shows the circuitry, in particular the state of the rectifier switching units Q1-Q4 and the safety switching units S1-S3, in a safety state of the WPT device 500, in which high current flow through the rectifier switching units Q1 and Q3 is prevented and the WPT receiver coil 401 is shorted. Fig. 7 shows substantially the same circuitry as Fig. 6 but in a normal operation state, in which the rectifier switching units Q1-Q4 and the safety switching units S1-S3 are in a different switching state (S1 and S2 are kept open while S3 is closed) so that the charging operation is performed and not influenced by the state of the safety switching units S1-S3. It shall be noted that in Fig. 6, the switching units S1-S3 and Q1-Q4 are drawn as switches in order to make it easier to visually see that they are statically switched on (RSON statically fully on), whereas in Fig. 7 they are drawn as MOSFETs because they are no more statically switched. There is no commutation pattern applied in the rectifier at all, i.e. , when S1 and S2 are closed, the active rectifier will switch on Q1 and Q3 in parallel, while it switches off Q2 and Q4.

[0060] Fig. 8 shows a circuit diagram of a third embodiment of a WPT device 600 according to the present invention that is configured to operate as VA. In this embodiment the safety switching unit S3 is not used, but additional safety switching units S4 and S5 are coupled between the rectifier 403 and the battery 406, in this exemplary implementation between the output terminals 405c, 405d (also called battery terminals) of the EMI filter 405 and the input terminals 406a, 406b of the battery 406. The safety switching units S4 and S5, which may be implemented as normally open relay unit, are controlled to be closed during a charging operation of the WPT device 600 and to be open at least during powering up of the WPT receiver coil 401 and / or in case of a damage or malfunction of the WPT device 600 or any element thereof, or optionally in case of a damage or malfunction of another WPT device that is configured to operate as GA. The safety switching units S4 and S5 may be part of the WPT device 600 or may be part of the EV, i.e., external to the WPT device. If the safety switching units S4 and S5 are part of the EV, depending upon the vehicle configuration, they may be controlled either directly by vehicle electronics or by the WPT device 600, in which case the control unit 407 may be configured to provide a control signal to control the safety switching units S4 and S5. 28.07.2025

[0061] 12

[0062] In an embodiment, the control unit 407 is configured to control the safety switching units S1 , S2 to be open only during the charging operation of the WPT device and to be closed at all other times and to control the third, fourth and fifth safety switching units S3, S4, S5 to be closed only during the charging operation of the WPT device and to be open at all other times. The safety switching units S1-S5 may be controlled to change their state simultaneously or independently.

[0063] Fig. 9 shows a flowchart 700 of the different states for the second embodiment of the WPT device 500 shown in Figs. 6 and 7. An embedded software may be used that goes through these steps to control the different switching units Q1-Q4 and S1-S3. When the WPT device is not performing a charging operation, the WPT device is in the safety state 701 , in which the rectifier switching units Q1 and Q3 are 100% on, the rectifier switching units Q2 and Q4 are 0% on (i.e. off), the safety switching units S1 and S2 are closed and the safety switching unit S3 is open. In step 702 an error detection is carried out to detect any malfunction, (potential) damage or other problem. If an error is detected, the WPT device remains in the safety state 701 . If no error is detected (and a charging operation shall be carried out), the WPT device is changed into the normal state, in which the rectifier switching units Q1-Q4 are modulated to rectify the provided AC power, the safety switching units S1 and S2 are open and the safety switching unit S3 is closed.

[0064] In step 704 another error detection is carried out, which may be the same error detection as in step 702, to detect any malfunction, (potential) damage or other problem. If no error is detected, the WPT device remains in the normal state 703. If an error is detected, the WPT device is changed into an error state 705, in which the rectifier switching units Q1 and Q3 are 100% on, the rectifier switching units Q2 and Q4 are 0% on (i.e. off), the safety switching units S1 and S2 are still open and the safety switching unit S3 are closed. Thus, in this exemplary embodiment, if error state 705 is activated, S1-S3 are not yet in safety state because it is still possible to prevent the system from damages, as it is still possible to control Q1-Q4 correctly. 28.07.2025

[0065] 13

[0066] The error detection is carried out in step 706 to detect if the number of errors is still below a predetermined error threshold (“max_error” in this example) or above this threshold. If no more error is detected in step 706, the WPT device is switched back into the normal mode 704 so that the charging operation can be continued. If further error(s) are detected in step 706, the number of errors is checked against the error threshold in step 707. If the error threshold is exceeded, the WPT device is switched into the safety state 701 . Otherwise the error state 705 is maintained and error detection step 706 is carried out again.

[0067] The WPT may comprises one or more detection means for detect one or more errors or problems. A circuit diagram of a corresponding embodiment of a WPT device 800 is shown in Fig. 10. In this embodiment, in addition to the elements shown in Fig. 8, a malfunction detector 801 is provided to detect a malfunction of one or more of the rectifier switching units Q1 -Q4 based on measurements of voltage measurement elements D1 -D4. Further, an overvoltage detector 802 is provided, which may be provided in addition to or instead of the malfunction detector 801 to detect an overvoltage over the capacitor 404 based on a measurement of voltage measurement element D5. Further detection means may be provided in addition or instead.

[0068] The detection means may generally be configured to detect: if there is a damage in the first and / or third rectifier switching unit(s) Q1 , Q3, in particular the rectifier switching unit(s), to which the safety switching unit(s) S1 , S2 are connected in parallel; if electric AC power is not or insufficiently available at the first and / or third rectifier switching unit(s) Q1 , Q3, in particular if there is insufficient voltage at one or more of the rectifier switching units to switch them on; if there is any malfunction (e.g. an overtemperature) in the WPT device (VA) or in a second WPT device (GA) comprising a WPT transmitter coil configured to inductively couple electric AC power into the WPT receiver coil of the WPT device; and if there is an overvoltage in a capacitor, e.g. the DC link capacitor optionally coupled between the output terminals of the rectifier. 28.07.2025

[0069] 14

[0070] The detection means comprise electronic circuitry configured to measure output voltage of the WPT device and / or the rectifier and / or to detect a malfunction in the WPT device, in particular the rectifier.

[0071] In summary, the present invention provides efficient countermeasures against or in case of malfunctions that keep the WPT receiver coil shorted during a malfunction or other problem in the VA or GA. Furthermore, the additional safety means can protect the battery also during such an event by isolating the battery from the power stage, which has the benefit of decreasing leakage current and protecting the battery in case of a damage in the power stage.

[0072] Providing the additional safety switching units S4 and S5 and controlling them independently of the safety switching units S1 and S2 may provide the advantage that, if S1 and S2 stuck and it may not be possible to open them anymore, it is beneficial to have the extra safety mechanism by means of S4 and S5.

[0073] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

[0074] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0075] Any reference signs in the claims should not be construed as limiting the scope. 15

[0076] List of reference signs

[0077] WPT system ground assembly (GA) vehicle assembly (VA) power source

[0078] AC / DC converter

[0079] DC to HF AC converter primary compensation circuit transmitter coil receiver coil secondary compensation circuit

[0080] AC / DC rectifier high voltage battery inductive charging coil assembly WPT device (as VA) receiving coil passive electronics rectifier (full bridge) DC link capacitor passive electronics (EMI filter) battery

[0081] WPT device (as VA with active protection) WPT device receiving coil passive electronics rectifier

[0082] DC link capacitor passive electronics battery control unit

[0083] WPT device 28.07.2025

[0084] 16

[0085] 600 WPT device

[0086] 700 flowchart

[0087] 800 WPT device

[0088] 801 , 802 detection means

[0089] Q1-Q4 rectifier switching units

[0090] S1-S5 safety switching units

Claims

28. 07.202517Claims1 . Wireless power transfer (WPT) device configured to be mounted in an electric vehicle for charging a traction battery of the electric vehicle, the WPT device comprising: a WPT receiver coil (401 ) configured to inductively receive electric AC power from a WPT transmitter coil; a rectifier (403) configured to convert the electric AC power into electric DC power, the rectifier comprising: a pair of input terminals (403a, 403b) configured to receive the electric AC power; a pair of output terminals (403c, 403d) configured to output the electric DC power; four rectifier switching units (Q1 , Q2, Q3, Q4) forming a full bridge rectifier; and at least two safety switching units (S1 , S2), wherein a first safety switching unit is coupled in parallel to a first rectifier switching unit of the full bridge rectifier that is coupled between a first input terminal and a first output terminal and a second safety switching unit is coupled in parallel to a third rectifier switching unit of the full bridge rectifier that is coupled between a second input terminal and the first output terminal; and a control unit (407) configured to control the at least two safety switching units to be open during a charging operation of the WPT device and to be closed at least during powering up of the WPT receiver coil and / or in case of a damage or malfunction of the WPT device or any element thereof.

2. WPT device according to claim 1 , wherein the first and second safety switching units (S1 , S2) are normally closed safety switching units.

3. WPT device according to claim 1 or 2,28.07.202518 wherein the control unit is (407) configured to control the at least two safety switching units (S1 , S2) to be open only during the charging operation of the WPT device and to be closed at all other times.

4. WPT device according to any preceding claim, further comprising a third safety switching unit (S3) coupled to the second output terminal of the rectifier, wherein the control unit (407) is configured to control the third safety switching unit to be closed during a charging operation of the WPT device and to be open at least during powering up of the WPT receiver coil and / or in case of a damage or malfunction of the WPT device or any element thereof.

5. WPT device according to any preceding claim, further comprising: a capacitor (404) and / or a filter unit (405) coupled to the output terminals of the rectifier; battery terminals (406a, 406b) at the output of the capacitor or the filter unit configured for coupling the traction battery to the WPT device; and a fourth safety switching unit (S4) coupled to a first battery terminal and / or a fifth safety switching unit (S5) coupled to a second battery terminal, wherein the control unit (407) is configured to control the fourth and / or fifth safety switching units to be closed during a charging operation of the WPT device and to be open at least during powering up of the WPT receiver coil and / or in case of a damage or malfunction of the WPT device or any element thereof.

6. WPT device according to claim 4 and / or 5, wherein the third, fourth and fifth safety switching units (S3, S4, S5) are normally open safety switching units.

7. WPT device according to any one of claims 4 to 6,28.07.202519 wherein the control unit (407) is configured to control the third, fourth and fifth safety switching units (S3, S4, S5) to be closed only during the charging operation of the WPT device and to be open at all other times.

8. WPT device according to any one of claims 1 to 4, wherein the control unit (407) is configured to provide a control signal to control one or more safety switching units (S4, S5) coupled to one or more input terminals of the traction battery to be closed during a charging operation of the WPT device and to be open at least during powering up of the WPT receiver coil and / or in case of a damage or malfunction of the WPT device or any element thereof.

9. WPT device according to any preceding claim, wherein the control unit (407) is configured to control the safety switching units (S1-S5) to change their state simultaneously or independently.

10. WPT device according to any preceding claim, further comprising detection means (801 , 802) configured to detect one or more of: if there is a damage in the first and / or third rectifier switching unit, if electric AC power is not or insufficiently available at the first and / or third rectifier switching unit, in particular if there is insufficient voltage at one or more of the rectifier switching units to switch them on, if there is any malfunction in the WPT device or in a second WPT device comprising a WPT transmitter coil configured to inductively couple electric AC power into the WPT receiver coil of the WPT device, and if there is an overvoltage in a capacitor coupled between the output terminals of the rectifier.11 . WPT device according to any claim 10, wherein the detection means (801 , 802) comprise electronic circuitry configured to measure output voltage of the WPT device and / or the rectifier and / or to detect a malfunction in the WPT device, in particular the rectifier.28.07.20252012. WPT device according to any preceding claim, wherein the rectifier switching units (Q1 , Q2, Q3, Q4) are semiconductor switches and / or the safety switching units are relay units, in particular electromagnetically controlled switches.

13. WPT system comprising a WPT device (101 , 400) according to any preceding claims and a traction battery (111 , 406) coupled to the WPT device.

14. WPT system according to claim 13, further comprising a second WPT device (101 ) comprising a WPT transmitter coil (107) configured to inductively couple electric AC power into the WPT receiver coil (108; 401 ) of the WPT device according to any one of claims 1 to 12.

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