Method and system for wireless power transmission for electric vehicles on road over adaptive

Abstract

A system for controlling the frequency of a wireless power signal transmitted from a plurality of power transmission segments positioned along a road. The system may include: a plurality of base stations positioned along a road, where, for each of the segments, each base station may include: a power converter configured to convert alternating current at a distribution frequency; a phase detection circuit configured to detect a voltage-current phase of a power supply signal on a powered one of the segments; and a frequency control circuit configured to control a power transfer frequency of the power supply signal on the powered segment based on the voltage-current phase so as to reduce an absolute value of the voltage-current phase to a predetermined level as long as a power receiving coil of the electric vehicle is passing through the powered power transmitting segment.

Description

Field of the Invention

[0001] The present invention generally relates to wireless power transfer in electric vehicles. Background of the Invention

[0003] Before setting forth the background of the invention, the following term definitions are provided:

[0004] The term "electric vehicle" generally refers to a vehicle that is powered, in whole or in part, by electrical energy stored (e.g., chemically) in a battery or the like. In this context, an "electric vehicle" additionally has means for receiving a wireless induced electromotive force (i.e., voltage), e.g., at a coil disposed on the underside of the vehicle, which electromotive force can be stored or otherwise used to recharge the battery. For the electromagnetic induction voltage to occur, the vehicle (i.e., the "conductor") can move relative to a magnetic field, which is, for example, projected around the road on which the vehicle is traveling. Optionally, the magnetic field can vary periodically (e.g., by the use of alternating current), thereby inducing a voltage at the vehicle.

[0005] The term "section" generally refers to a portion of a road or highway that has been modified, for example, to include a medium for wirelessly transmitting power (i.e., the "power transmitter"). This may mean that the road includes a plurality of coils embedded beneath the surface of the section, which are operable to emit a magnetic field. In a typical arrangement, the medium (coils) can be connected to an alternating current power source, such as the electrical grid, and can generate a varying magnetic field, thereby inducing a voltage in any adjacent conductor. A viable method for powering road electric vehicles via wireless power transfer is disclosed in EP 3089886B1, which is incorporated herein by reference.

[0006] Figure 1 is a block diagram illustrating a prior art wireless power transfer system 100. The wireless power transfer system 100 can include a plurality of electric vehicles 150, which include power receivers attached, for example, to the underside of the vehicle. The plurality of electric vehicles can also travel on a section 101 having one or more power transmitters 120, which are, for example, disposed beneath the surface of the section and powered by a power converter 122 connected to the electrical grid. In some embodiments, each power receiver and power transmitter can include, for example, one or more wound or toroidal coils coupled to an alternating current power source. In some arrangements, these coils are operable to emit a static or varying magnetic field into the vicinity, e.g., around the section or a portion thereof, surrounding the coils. As each electric vehicle travels along the section 101, the magnetic field formed by the power transmitters in the section 101 induces a voltage in each power receiver and is stored and / or converted by the electric vehicle into, for example, chemical energy in a battery. In alternative embodiments, the induced energy can be immediately used by the engine of the electric vehicle without storage.

[0007] When an electric vehicle passes over a transmitting coil, the alignment of the receiving coil relative to the transmitting coil changes. This can cause the resonant frequency of the receiving array to decrease relative to the operating resonant frequency of the transmitting array, which may result in non-optimal power transfer.

[0008] Overview of the Invention

[0009] The present invention provides a system for controlling the frequency of power supplied to an electric vehicle traveling on a road via an air transmitter. The transmitter side has a control unit that monitors the voltage-current phase and infers the displacement between the receiver-side coil and the corresponding transmitter-side coil. The frequency is then dynamically corrected based on this displacement to ensure resonant or near-resonant operation.

[0010] According to some embodiments of the present invention, there is provided a system for controlling the frequency of a wireless power signal transmitted by a plurality of power transmission segments located along a road and beneath the road surface for powering a receiving coil on an electric vehicle moving along the road, each power transmission segment including two or more transmitting coils, the system comprising: a plurality of base stations located along the road, each base station being configured to selectively supply power to a plurality of segments in series independent wiring, wherein for each of the segments powered by the base station, each base station includes: a power converter for each segment powered by the base station, the power converter being configured to convert alternating current from the power grid at a distribution frequency and output a power supply signal in a power transmission frequency range; a phase detection circuit configured to detect the voltage-current phase of the power supply signal on one of the powered segments; and a frequency control circuit configured to control the power transmission frequency of the power supply signal on the powered segment based on the voltage-current phase so as to reduce the absolute value of the voltage-current phase to a predetermined level as long as the power receiving coil of the electric vehicle is passing over one of the powered ones of the power transmission segments.

[0011] These and other advantages of the present invention will be elaborated in detail in the following description. Brief Description of the Drawings

[0013] For a better understanding of the present invention and to show how it may be implemented, reference is made, by way of example only, to the accompanying drawings in which like numerals represent corresponding elements or parts. In the drawings:

[0014] Figure 1 is a block diagram of a wireless power transmission system for an electric vehicle on a road according to the prior art;

[0015] Figure 2A and Figure 2Bis a diagram showing the arrangement of receiving coils in a transmitting array and a receiving array according to some embodiments of the present invention;

[0016] Figure 3 is a diagram showing a system according to some embodiments of the present invention;

[0017] Figure 4A and Figure 4B is a graph showing how the power of different frequency bands for a generator can vary according to some embodiments of the present invention, and this variation should change based on the displacement bands of the receiver-side coil relative to the corresponding transmitter-side coil; and

[0018] Figure 5 is a flowchart illustrating a method according to some embodiments of the present invention.

[0019] Detailed Description of the Invention

[0020] Now, with particular reference to the drawings in detail, it is emphasized that the details shown are for purposes of illustration and are only for discussing the preferred embodiments of the present invention, and are presented in order to provide what is considered to be the most useful and easily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show the structural details of the present invention in more detail than is necessary for a basic understanding of the present invention. The description in conjunction with the drawings makes it apparent to those skilled in the art how several forms of the present invention can be embodied in practice.

[0021] Before explaining the embodiments of the present invention in detail, it should be understood that the present invention is not limited in its application to the details of the construction and arrangement of components set forth in the following description or shown in the drawings. The present invention is applicable to other embodiments and can be practiced or carried out in various ways. In addition, it should be understood that the terminology and phrases used herein are for the purpose of description and should not be regarded as restrictive.

[0022] Figure 2A and Figure 2BAn exemplary arrangement of receiver coils 210 in a receiver array 200 is shown. The measurements shown are only exemplary dimensions and are not intended to be restrictive. The receiver coils 210 may be disposed on the bottom side of an electric vehicle (not shown), parallel to a road section having a transmitting coil 220 disposed thereon. The receiver coils 210 may receive power transmitted by the transmitting coil 220. The lower receiver coils 212 may be placed side by side, thereby defining a joining line 212a in the shared plane of the road section and the coils. Such joined coils 212 may be referred to as “figure-eight” coils. The upper receiver coils 214 may be placed on top of the lower receiver coils 212. The upper receiver coils 214 may have dimensions different from those of the lower receiver coils 212, and the upper receiver coils 214 may have the same dimensions as the transmitting coil 220. The upper receiver coils 214 may be placed such that their geometric centers 214a lie on the joining line 212a of the lower receiver coils 212. The geometric center of an object is defined as the average position of all points of the object in all coordinate directions. The configuration of the upper and lower receiver coils 210 may be repeated periodically along the bottom side of the electric vehicle. The receiver coils 210 may be circular or rectangular or variants thereof, such as oval or oblong. The receiver array 200 may include a ferrite plate 205. When deployed, the ferrite plate 205 is used to shape and contain the magnetic flux so as to prevent any adverse effects due to the transmission of the magnetic flux into the interior of the electric vehicle.

[0023] It has been found that such a configuration of the upper and lower receiver coils 210 provides optimal power transfer under fixed-frequency operation of a fixed-alignment transmitting coil 220. However, the relative movement between the transmitting coil 220 and the receiver coils 210 due to the movement of the electric vehicle reduces the efficiency of power transfer due to the change in the coupling coefficient. One solution may be to power the transmitter coil 220 with an average power. However, this is not effective.

[0024] Therefore, it may be useful to dynamically adjust the power transfer characteristics of the transmitter coil in response to information about the position of the receiver coil relative to the transmitter coil. For example, since power transfer occurs over a road section of only 2 m and the positioning of the coils relative to each other occurs on the centimeter scale, a system with a precise positioning with an error on the centimeter scale is not suitable.

[0025] Figure 3Shows a wireless power system 300 for an electric vehicle 350 on a road 030. The road 030 may have a section 301 that is provided with a transmitter coil 320 (possibly below the surface of the road 030). The section 301 may be powered by a power converter 322, which itself may be powered by a power grid (not shown). The power converter 322 may be connected to a base station (not shown). The base station may be able to access a database of electric vehicles that subscribe to an electricity payment plan. The power converter 322 may be connected to a capacitor bank 326 via an access cable 324. The access cable 324 may carry different types of electrical signals. For example, the access cable 324 may include at least one communication channel and at least one power delivery channel. The electric vehicle 350 may travel on the road 030 in a direction 302 towards the section 301. The electric vehicle 350 may have a power receiver array that includes a plurality of receiving coils 310 that may be disposed on the bottom side of the electric vehicle 350.

[0026] The electric vehicle 350 may also have a communication loop 360. The communication loop 360 may transmit a communication signal 362. The communication signal 362 may be modulated with an identity (ID) code so as to be uniquely associated with the electric vehicle 350. For example, the ID code may include, but is not limited to: a vehicle registration number; a driver registration number; or a subscription number. The communication signal 362 may be transmitted at a frequency higher than the frequency of the power transmitted by the transmitter coil 320.

[0027] The communication signal 362 may be received by a communication antenna loop 365 associated with the section 301. The communication antenna loop 365 may be connected to the capacitor bank 326. The communication antenna loop 365 may be configured to control the power transmission of the transmitter coil 320. The communication antenna loop 365 may be configured to initialize the power transmission of the transmitter coil 320 only in response to a communication signal 362 that identifies the electric vehicle 350 as being associated with a valid subscription to an electricity payment plan. The determination of the validity of the communication signal 362 may be performed at the base station and relayed back to the section 301.

[0028] In operation, the power of each power converter 322 of the powered section 365 is monitored and changed in an adaptive manner to ensure a resonant or near-resonant state. This can be achieved only on the power transmission side without any control or measurement unit on the power reception side, that is, without monitoring any conditions on the electric vehicle.

[0029] According to some embodiments of the present invention, the resonant frequency is set to the frequency at which the current-voltage phase of the power converter 322 is equal to zero.

[0030] According to some embodiments of the present invention, the resonant frequency of the transmitter segment is measured without any power receivers (e.g., electric vehicles) above it and is defined as the zero-load resonance (ZLR).

[0031] When an electric vehicle travels along a road, its communication transmitter continuously sends a communication signal requesting power supply to the section it is about to travel. The power supply request signal (communication signal frequency) includes an ID code modulated thereon, so that the section and the base station can identify the vehicle and energize the power transmission side accordingly. Once the power receiving unit of the electric vehicle approaches a given power transmission segment, a dedicated communication receiver on the power transmission segment receives and detects the identification code and activates the converter of the transmission segment at a minimum power level (so that it can measure current, voltage, phase, etc.).

[0032] From this point on, after the transmitter recognizes the communication, it starts to supply power to the primary coil with a minimum current. Once the receiver unit of the electric vehicle passes through the transmitter segment, the common resonant frequency decreases, and as the coupling between them increases, the resonant frequency will decrease.

[0033] To solve the decrease in the resonant frequency, according to some embodiments of the present invention, the converter associated with a specific transmitter segment is monitored to detect the phase difference between the voltage and current of the transmitter segment. In response to detecting such a phase, the converter frequency is modified until the phase is zero again.

[0034] According to some embodiments of the present invention, in order to determine the operating frequency of the converter, a look-up table or a similar mechanism can be used to map the measured voltage-current phase and the required frequency change.

[0035] A similar look-up table can be used to determine the displacement of the power receiver unit relative to the power transmission segment, and thus determine the precise position of the electric vehicle relative to the road.

[0036] According to some embodiments of the present invention, a system for controlling the frequency of a wireless power signal is provided. The wireless power signal is transmitted by a plurality of power transmission segments located along a road and below the road surface for powering a receiving coil on an electric vehicle moving along the road. Each power transmission segment includes two or more transmitting coils. The system includes: a plurality of base stations located along the road, each base station being configured to selectively power a plurality of segments in a series independent wiring. For each of the segments powered by the base station, each base station includes: a power converter for each segment powered by the base station, the power converter being configured to convert alternating current at a distribution frequency from a power grid and output a power supply signal in a power transmission frequency range; a phase detection circuit configured to detect the voltage-current phase of the power supply signal on one of the powered segments; and a frequency control circuit configured to control the power transmission frequency of the power supply signal on the powered segment based on the voltage-current phase so as to reduce the absolute value of the voltage-current phase to a predetermined level as long as the power receiving coil of the electric vehicle is passing through one of the powered ones of the power transmission segments.

[0037] According to some embodiments of the present invention, the power transmission segment includes a communication receiver configured to receive a power request signal from an authorized electric vehicle, and wherein the converter is turned on only when the power request signal is authorized.

[0038] According to some embodiments of the present invention, the power transmission frequency range is 80KHz to 90Khz.

[0039] According to some embodiments of the present invention, the frequency of the power transmission signal can be modified based on the voltage-current phase to ensure that the power transmission coil and the power receiving coil operate in a resonant or near-resonant manner throughout the process when the power receiving coil passes through one of the power transmission segments.

[0040] According to some embodiments of the present invention, the frequency control circuit can also be configured to increase the power level of the power supply signal based on the voltage-current phase.

[0041] According to some embodiments of the present invention, the frequency control circuit can be configured to use a switching circuit to modify the frequency of the power transmission signal.

[0042] According to some embodiments of the present invention, the frequency control circuit can also be configured to increase the power level of the power supply signal based on the voltage-current phase by controlling the duty cycle of the switching circuit for different frequency bands.

[0043] According to some embodiments of the present invention, where the voltage-current phase represents one of a plurality of frequency bands, each frequency band representing the degree of overlap between the power transmission coil of one of the plurality of power transmission segments and the power receiving coil of the electric vehicle when the electric vehicle passes over one of the plurality of power transmission segments.

[0044] According to some embodiments of the present invention, the base station may be configured to calculate the displacement of the receiving coil of the vehicle relative to the power transmission coil of one of the plurality of power transmission segments based on the voltage-current phase.

[0045] According to some embodiments of the present invention, the voltage-current phase represents one of a plurality of frequency bands, each frequency band representing the degree of overlap between the power transmission coil of one of the plurality of power transmission segments and the power receiving coil of the electric vehicle when the electric vehicle passes over one of the plurality of power transmission segments.

[0046] According to some embodiments of the present invention, ensure that the power supply is disconnected under zero load to ensure that power supply to the transmitter segment does not occur when there is no vehicle above the transmitter segment. This is done for safety and power efficiency.

[0047] Figure 4A and Figure 4B is a graph showing how the power at different frequency bands for a generator can vary according to some embodiments of the present invention, and this variation should change based on the displacement frequency band of the receiver-side coil relative to the corresponding transmitter-side coil.

[0048] Figure 5 is a flowchart illustrating a method according to some embodiments of the present invention. The method includes the following steps: converting alternating current at the distribution frequency from the power grid and outputting a power supply signal in the power transmission frequency range 510; controlling the power transmission frequency of the power supply signal based on the voltage-current phase of the power supply signal 520; in response to detecting that an authorized electric vehicle having a power receiving coil is approaching one of the power transmission segments, turning on to output the power supply signal at a minimum power level sufficient for detecting the voltage-current phase 530; in response to the authorized electric vehicle passing over the one of the power transmission segments, turning on to the power transmission level and detecting the voltage-current phase of the power supply signal 540; and modifying the frequency of the power transmission signal based on the voltage-current phase so as to reduce the voltage-current phase to zero as long as the power receiving coil passes over one of the power transmission segments 550.

[0049] The flowcharts and block diagrams referred to above illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions noted in this block may occur out of the order noted in the figures. For example, two blocks shown in succession may in fact be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and / or flowchart illustrations, and combinations of blocks in the block diagrams and / or flowchart illustrations, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

[0050] As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a system or apparatus. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an embodiment combining software and hardware aspects, which may generally be referred to herein as a "circuit," "module," or "system."

[0051] The foregoing drawings illustrate the architecture, functionality, and operation of possible implementations of systems and apparatuses according to various embodiments of the present invention. In the case where the foregoing is described, the embodiments are examples or implementations of the present invention. Various occurrences of "one embodiment," "an embodiment," or "some embodiments" are not necessarily all referring to the same embodiment.

[0052] Although various features of the present invention may be described in the context of a single embodiment, these features may also be provided separately or in any suitable combination. Conversely, although the present invention may be described herein in the context of separate embodiments for clarity, the present invention may also be implemented in a single embodiment.

[0053] References in the specification to "some embodiments," "an embodiment," "one embodiment," or "other embodiments" mean that the particular features, structures, or characteristics described in connection with the embodiments are included in at least some embodiments of the invention but not necessarily in all embodiments. It will also be recognized that the aspects of the present invention described above may be combined in the embodiments of the present invention or may coexist in other ways.

[0054] It should be understood that the terminology and phrases used herein should not be construed as limiting and are only for descriptive purposes.

[0055] The principles and use of the teachings of the present invention may be better understood with reference to the accompanying specification, drawings, and examples.

[0056] It should be understood that the details set forth herein do not limit the application of the present invention.

[0057] Furthermore, it should be understood that the present invention can be implemented or carried out in various ways, and the present invention can be realized in embodiments different from those summarized in the above description.

[0058] It should be understood that the terms "including", "comprising", "consisting of" and their grammatical variants do not exclude the addition of one or more components, features, steps or integers or groups thereof, and the terms should be construed as designating the components, features, steps or integers.

[0059] If the specification or claims refer to "additional" elements, it does not exclude there being more than one additional element.

[0060] It should be understood that where the claims or specification refer to "a" or "an" element, such reference is not to be construed as meaning only one of such element.

[0061] It should be understood that where the specification states that a component, feature, structure or property "may", "might", "can" or "could" be included, that particular component, feature, structure or property need not be included.

[0062] Where applicable, while state diagrams, flowcharts or both may be used to describe embodiments, the present invention is not limited to these diagrams or the corresponding descriptions. For example, the flow need not move through each shown box or state, or move in exactly the same order as shown and described.

[0063] The method of the present invention can be realized by manually, automatically or a combination thereof performing or completing selected steps or tasks.

[0064] The term "method" can refer to the manner, means, technique and process for accomplishing a given task, including but not limited to those manners, means, techniques and processes known to practitioners in the field to which the present invention pertains or those manners, means, techniques and processes readily developed from known manners, means, techniques and processes.

[0065] The descriptions, examples and materials presented in the claims and specification should not be construed as restrictive, but rather as merely illustrative.

[0066] The meanings of the technical and scientific terms used herein are those commonly understood by those of ordinary skill in the art to which the present invention pertains, unless otherwise defined.

[0067] The present invention may be practiced or tested with materials equivalent or similar to those described herein.

[0068] Although the present invention has been described in terms of a limited number of embodiments, these should not be construed as limiting the scope of the invention, but rather as examples of some preferred embodiments. Other or equivalent variations, modifications, and applications are also within the scope of the invention. Accordingly, the scope of the invention should not be limited by what has been described so far, but rather by the appended claims and their legal equivalents.

Claims

1. A system for controlling the frequency of a wireless power signal, the wireless power signal being transmitted by a plurality of power transmission segments positioned along a road and below the surface of the road to supply power to a receiving coil on an electric vehicle moving along the road, each power transmission segment including two or more transmission coils, the system comprising: A plurality of base stations positioned along the road, each base station being configured to selectively power a plurality of segments in a series of independent wirings, wherein for each segment powered by the base station, each base station includes: A power converter for each segment powered by the base station, the power converter being configured to convert alternating current at a distribution frequency from the power grid and output a power supply signal within a power transmission frequency range; A phase detection circuit configured to detect the voltage-current phase of the power supply signal on one powered segment in the segment; and A frequency control circuit configured to control the power transmission frequency of the power supply signal on the powered segment based on the voltage-current phase so as to reduce the absolute value of the voltage-current phase to a predetermined level as long as the power receiving coil of the electric vehicle is passing through the one in one of the powered segments of the power transmitting segments.

2. The system according to claim 1, wherein, The power transmitting segment includes a communication receiver configured to receive a power request signal from an authorized electric vehicle, and wherein the converter is turned on only when the power request signal is authorized.

3. The system according to claim 1, wherein, The power transmission frequency range is 80KHz to 90Khz.

4. The system according to claim 1, wherein, Modify the frequency of the power transmission signal based on the voltage-current phase to ensure that the power transmitting coil and the power receiving coil operate in a resonant or near-resonant manner throughout the process when the power receiving coil passes through one of the power transmitting segments.

5. The system according to claim 3, wherein, The frequency control circuit is further configured to increase the power level of the power supply signal based on the voltage-current phase.

6. The system according to claim 1, wherein, The frequency control circuit is configured to use a switching circuit to modify the frequency of the power transmission signal.

7. The system according to claim 6, wherein, The frequency control circuit is further configured to: increase the power level of the power supply signal by controlling the duty cycle of the switching circuit for different frequency bands based on the voltage-current phase.

8. The system according to claim 1, wherein, The voltage-current phase represents one of a plurality of frequency bands, each frequency band representing the degree of overlap between the power transmitting coil of one of the plurality of power transmitting segments and the power receiving coil of the electric vehicle when the electric vehicle passes through one of the plurality of power transmitting segments.

9. The system according to claim 1, wherein, The base station is configured to calculate the displacement of the receiving coil of the vehicle relative to the power transmitting coil of one of the plurality of power transmitting segments based on the voltage-current phase.

10. The system according to claim 9, wherein, The voltage-current phase represents one of a plurality of frequency bands, each frequency band representing the degree of overlap between the power transmitting coil of one of the plurality of power transmitting segments and the power receiving coil of the electric vehicle when the electric vehicle passes through one of the plurality of power transmitting segments.

11. A method for controlling the frequency of a wireless power signal, the wireless power signal being transmitted by a plurality of power transmission segments positioned along a road and below the surface of the road to supply power to a receiving coil on an electric vehicle moving along the road, each power transmission segment including two or more transmission coils, the method comprising: Selectively power a plurality of segments in a series of independent wirings via a plurality of base stations positioned along the road; For each of the segments powered by the base station, convert alternating current at a distribution frequency from the power grid and output a power supply signal within a power transmission frequency range; Detect the voltage-current phase of the power supply signal on one of the powered segments in the said segment; and Based on the voltage-current phase, control the power transfer frequency of the power supply signal on the powered segment so that as long as the power receiving coil of the electric vehicle is passing over the one in one of the powered segments of the power transmitting segment, the absolute value of the voltage-current phase is reduced to a predetermined level.

12. The method according to claim 11, wherein, The power transmitting segment includes a communication receiver configured to receive a power request signal from an authorized electric vehicle, and wherein the converter is switched on only when the power request signal is authorized.

13. The method according to claim 11, wherein, The power transfer frequency ranges from 80KHz to 90Khz.

14. The method according to claim 11, wherein, Modify the frequency of the power transfer signal based on the voltage-current phase to ensure that the power transmitting coil and the power receiving coil operate in a resonant or near-resonant manner throughout the process when the power receiving coil passes over one of the power transmitting segments.

15. The method according to claim 13, wherein The controlling of the power transfer frequency includes increasing the power level of the power supply signal based on the voltage-current phase.

16. The method according to claim 11, wherein The controlling of the power transfer frequency includes modifying the frequency of the power transmitting signal using a switching circuit.

17. The method according to claim 16, wherein The controlling of the power transfer frequency includes: based on the voltage-current phase, increasing the power level of the power supply signal by controlling the duty cycle of the switching circuit for different frequency bands.

18. The method according to claim 11, wherein The voltage-current phase represents one of a plurality of frequency bands, and each frequency band represents the degree of overlap between the power transmitting coil of one of the plurality of power transmitting segments and the power receiving coil of the electric vehicle when the electric vehicle passes over one of the plurality of power transmitting segments.

19. The method according to claim 11, further comprising calculating a displacement of the receiving coil of the vehicle relative to the power transmitting coil of one of the plurality of power transmitting segments based on the voltage-current phase.

20. The method according to claim 19, wherein The voltage-current phase represents one of a plurality of frequency bands, and each frequency band represents the degree of overlap between the power transmitting coil of one of the plurality of power transmitting segments and the power receiving coil of the electric vehicle when the electric vehicle passes over one of the plurality of power transmitting segments.

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