Wireless power system and power transmission system

Abstract

The invention relates to a wireless power system (1) comprising a first unit (10, 20) comprising a pad (11, 21) configured to wirelessly transmit or receive power and a wireless communication unit (12, 22), and a control unit (2). Wherein the pad (11, 21) is configured to wirelessly transmit or receive power to or from a second unit (10, 20), the wireless communication unit (12, 22) is configured to receive a communication signal (32) from the second unit (10, 20), and the control unit (2) is configured to detect at least one phase value of the communication signal (32), and determining a relative position of the wireless communication unit (12, 22) and the second unit (10, 20) based on the detected phase value. Furthermore, the invention relates to a power transmission system (100) comprising said wireless power system (1) and said second unit (10, 20).

Description

Wireless power systems and power transmission systems Technical Field

[0001] This invention relates to a wireless power system and a power transmission system. Background Technology

[0002] Wireless power systems for wirelessly transmitting power between transmitting and receiving units (often referred to as "primary units" and "secondary units" or "TX / RX") are generally known. Relative positioning (often called "alignment") of these units is often a challenge for efficient power transmission.

[0003] For example, some attempts to overcome this challenge have been known from US2013 / 0033224 A1, US10,072,947, US2020 / 0290467 A1 and US2017 / 0111088 A1.

[0004] However, these known systems have several flaws.

[0005] On the one hand, common solutions, as described in US2013 / 0033224 A1 or US2020 / 0290467 A1, involve multiple additional coils that also receive power on the receiving side, where alignment is determined by comparing electrical parameters such as the voltage induced in these coils or the resonant frequency. However, this has the following drawbacks: the additional coils are costly and reduce efficiency in terms of heat and power transmission. Furthermore, its accuracy is relatively low.

[0006] Traditional alignment methods typically rely either on additional sensors or beacons, which are costly, bulky, and inefficient, or on receiving power via wireless transmission, which is inaccurate when providing two-dimensional or three-dimensional alignment between the primary and secondary pads and reduces transmission efficiency. Summary of the Invention

[0007] The object of this invention is to overcome these deficiencies. In particular, an object of this invention is to provide a wireless power system capable of accurately and efficiently determining the relative position of its first unit relative to a second unit. Another object of this invention is to provide a power transmission system having a first unit and a second unit, capable of accurately and efficiently determining the relative position between the first unit and the second unit.

[0008] The wireless power system of the present invention achieves these objectives. The wireless power system includes a first unit comprising a pad configured to wirelessly transmit or receive power and a wireless communication unit. The first unit further includes a control unit. The pad is configured to wirelessly transmit power to or receive power from a second unit, and the wireless communication unit is configured to receive communication signals from the second unit. The control unit is configured to detect the phase value of the communication signal and determine the relative position of the wireless communication unit and the second unit based on the detected phase value.

[0009] In other words, the control unit is configured to determine the relative position or distance between the wireless communication unit included in the first unit of the wireless power system and the external second unit. For example, the first unit may be a receiving unit (secondary-side unit), and the control unit is configured to determine its alignment with a transmitting unit (primary-side unit). In some examples, the first unit may be contained within a vehicle, while the second unit may be located in an external ground unit or an external wall unit. This is also true in examples where the first unit is a ground unit or a wall unit and the second unit is an external vehicle-mounted unit.

[0010] One advantage of the present invention is that the wireless power system comprises only the first unit. Thus, alignment can be performed by the control unit largely independently of the configuration of the second unit. Preferably, the second unit is configured to at least transmit, and in particular, receive, the communication signal.

[0011] In this document, the term "relative position" refers to at least one-dimensional, two-dimensional, or even three-dimensional distance from the first unit to the second unit. In one embodiment, the absolute position of one of the first unit and the second unit is known. For example, one of the units is located in a predetermined location, such as a parking lot or charging station. Thus, the absolute positions of these units can be determined by the detected relative position and the known predetermined position. Furthermore, in some preferred embodiments, the term "relative position" also refers to the alignment angle (or spatial angle) between the first unit and the second unit.

[0012] In the context of this article, power transmission and / or reception may be referred to simply as "power transmission" in some cases.

[0013] Here, the wireless power system uses the phase value of the communication signal to determine the relative position and control alignment with the second unit. Thus, apart from the components used in the pad, the wireless power system (especially the first unit) requires no other power receiving or transmitting coils or magnetic materials to perform alignment. Furthermore, the control unit is configured to determine the relative position solely by analyzing the phase value of the communication signal. In other words, for example, the communication signal itself does not carry the information used by the control unit to determine the relative position; that is, this information is not encoded into the signal. Instead, the control unit preferably determines the relative position based solely on the physical characteristics of the communication signal, rather than any encoded information therein. In some embodiments, such encoded information may be used in addition to the phase-value-based position detection of the present invention.

[0014] In some embodiments, the control unit is configured to receive communication signals via a wireless communication unit and additionally or simultaneously use the communication signals to detect relative position. Thus, the pad does not require an additional sensor to detect relative position by detecting the received power through a magnetic field transmitted by electricity, because position detection can be based solely on the communication signals.

[0015] In one embodiment, the wireless communication unit is configured to receive and provide a near-field communication link as a communication signal. Further, the communication signal is a pad-to-pad link (commonly referred to as "PPL"). Exemplarily, the communication signal conveys information such as identifiers of the first and second units, power transmission requirements for controlling power transmission via the pads, etc.

[0016] In some embodiments, in a near-field communication link, for example, a signal of 10 MHz to 15 MHz, such as a signal of 13.56 MHz, is used as a carrier for data transmission.

[0017] In some embodiments, the pad for wireless power transmission and the wireless communication unit are disposed within a common housing of the first unit. Thus, the relative position of the wireless communication unit to the second unit substantially corresponds to the relative position of the pad, and in particular, the relative position of the wireless power system to the second unit.

[0018] Typically, the phase of a wireless communication signal can depend on the wireless communication units, i.e., the distance between the first and second units. Therefore, in some embodiments, the distance can be determined by using the phase of the received wireless communication signal as the phase value. Specifically, in some embodiments, the absolute phase of the transmitted communication signal (e.g., transmitted by the second unit) is predetermined and known to the control unit. In some examples, the control unit can determine the distance between the first and second units by comparing the received phase with the transmitted phase. For example, there is a predetermined relationship between the phase of the wireless communication signal and the distance, particularly related to the refractive index of the medium (i.e., air and / or components of a wireless power system, especially a pad). This predetermined relationship can be measured and stored in the control unit, for example, as a lookup table comparing phase (especially phase difference, and / or phase changes in time and / or space) with corresponding distances. Therefore, the control unit refers to the lookup table to determine the distance based on the predetermined relationship based on the measured phase value.

[0019] For example, the phase of the wireless communication signal can also depend on distance due to the different propagation paths of the materials of the wireless power system and / or the second unit, as well as the medium separating the two (primarily air) (also known as the "phase constant," i.e., the imaginary part of the propagation constant). As previously mentioned, this relationship can be predetermined and stored, for example, as a lookup table stored in the control unit.

[0020] In some implementations, the phase value is used to determine the time of flight (TOF) of the communication signal. This can be achieved, for example, directly using the phase value, or indirectly using the aforementioned distance relationship and the speed of light.

[0021] In some implementations, the control unit is configured to calculate the phase relationship between multiple receptions of the communication signal as a phase value, and determine the relative position based on the calculated phase relationship. In some examples, the phase relationship is a comparison of phase values ​​between multiple receptions. This has the advantage that the absolute phase of the communication signal does not need to be known, although this information can be incorporated.

[0022] In some examples, the phase relationship is the phase difference between multiple receptions of the communication signal. In other words, the control unit is configured to calculate the phase difference between multiple receptions of the communication signal by the wireless communication unit. Therefore, the phase of the communication signal during and between multiple receptions can be compared, which provides an efficient method for alignment detection.

[0023] In some embodiments, a phase relationship, such as a phase difference, can be determined between multiple receptions in time and / or space. Typically, if the first unit is moving, multiple receptions in time will also be multiple receptions in space. Furthermore, as will be described in detail below, if the first unit includes multiple receiving antennas, multiple receptions in space can also be simultaneous and can also occur at different times.

[0024] In some implementations, the control unit is configured to calculate a time phase relationship as a phase relationship. This time phase relationship is calculated between multiple receptions (i.e., multiple samples) corresponding to different time points (especially during relative movement between the wireless communication unit and the second unit). For example, timestamps corresponding to each reception in the multiple receptions are recorded. The multiple transmissions of the communication signal (corresponding to multiple receptions) share a common phase propagation and reference because the transmitted signals have continuous phase.

[0025] In some embodiments, the control unit is configured to calculate the time phase relationship between two receptions at different time points (e.g., at least three receptions, between the first and second receptions and between the second and third receptions), and to calculate the change of the time phase relationship over time. By calculating the change of the time phase relationship over time, the control unit can determine whether the distance between these units is changing and in which direction it is changing, for example, whether the first unit is moving closer to the second unit or vice versa. Alignment can then be performed based on this.

[0026] In some embodiments, the control unit is also configured to compare changes over time with input and / or predetermined movement information from the wireless communication unit, including, for example, the amount of movement (distance) and / or direction. In other words, the control unit can use changes over time as feedback related to the input and / or predetermined movement information, thereby enabling alignment with higher accuracy. For example, the control unit is also configured to receive information or signals based on the relative movement between the wireless communication unit and the second unit within time frames between multiple receptions. Using this additional information, changes over time in the time phase relationship can be correlated with the relative movement, allowing the control unit to determine the distance and / or direction for optimal alignment.

[0027] For example, if the distance traveled between multiple receptions in time is known, this can be understood as substantially similar to multiple antennas at known locations simultaneously receiving wireless communication signals at different locations (time and travel are equivalent to distance).

[0028] In some embodiments, when calculating the time phase relationship, the time difference (time stamp difference) between multiple receptions is below a predetermined threshold, especially to prevent erroneous results caused by the symmetry of the time phase relationship (particularly the time phase difference). For example, the time difference corresponds to at most 2π or at most 1π of the wireless communication signal.

[0029] In some embodiments, the wireless communication unit includes at least one main communication antenna for transmitting and receiving the communication signals. Furthermore, the wireless communication unit includes at least one, for example, two to four, auxiliary sensing antennas for detecting relative position. This allows for advantageous simultaneous reception of communication signals at different locations / spaces.

[0030] For example, by combining a predetermined absolute phase and utilizing predetermined information about the relative positions of the auxiliary sensing antennas relative to each other and / or relative to the main communication antenna, the relative position can be determined with high precision. Furthermore, in addition to the relative position in spatial coordinates (i.e., distance), the relative position in terms of alignment angle (or spatial angle) can also be detected.

[0031] In some embodiments, the auxiliary sensing antenna is configured to receive communication signals from the second unit. The auxiliary sensing antenna is configured to use the received communication signals only for detecting relative position and not for information transmission. For example, the control unit is configured to decode only the communication signals from the main communication antenna. Correspondingly, the control unit is not configured to decode (i.e., is configured not to decode) the communication signals received by the auxiliary sensing antenna. Further, the communication signals received by the main communication antenna may also be used to determine relative position, or may be used only for decoding.

[0032] In some embodiments, the control unit is configured to calculate, as a phase value, the spatial phase relationship between multiple receptions of communication signals from different antenna pairs corresponding to at least one main communication antenna and at least one auxiliary sensing antenna. Furthermore, the control unit is configured to determine relative positions based on the calculated spatial phase relationship. Preferably, the control unit is configured to determine the spatial phase relationship for (within the scope of the art) multiple receptions of simultaneously received communication signals. In other embodiments, the multiple receptions used for determination are performed at different locations (antennas) and at different times (e.g., when the first unit and the second unit move relative to each other).

[0033] In some embodiments, the control unit is configured to calculate the difference between the phases received multiple times as a spatial phase relationship and determine the distance between different antennas and the second unit.

[0034] For example, the control unit calculates the phase difference between the phases of the communication signals received by each auxiliary sensing antenna. Since the phase difference can depend on the distance between the first and second units, the control unit can determine which auxiliary sensing antenna (or main communication antenna) is closer to the second unit. If the phase differences between all antennas are substantially equal, the control unit can determine that alignment is complete.

[0035] In some implementations, multiple auxiliary sensing antennas are arranged around the main communication antenna, particularly symmetrically around it. This allows for the low-cost manufacture of the wireless communication unit. Furthermore, this allows the wireless power system to be easily implemented as a transmitting (ground) side or a receiving (vehicle) side.

[0036] In some examples, the control unit is also configured to detect the signal strength of the communication signal, for example, by the maximum amplitude and / or maximum peak-to-peak value, and determine the relative position of the wireless communication unit and the second unit based on the detected signal strength and the detected phase. This further improves alignment accuracy. Furthermore, this has the advantage that, within a specific distance range, position determination based on phase or amplitude will be more accurate than the other, thus allowing for different determination methods to be used for different ranges. Additionally, the control unit is configured to use the aforementioned signal strength detection to verify the determined distance calculated from the phase value, and vice versa. This redundancy further improves accuracy.

[0037] In some implementations, the wireless communication unit and the second unit are separated by a certain distance. The control unit is configured as follows:

[0038] When the relative position is equal to or less than a first predetermined distance value, a communication signal is used to detect the relative position; and / or

[0039] Data is transmitted using communication signals when the distance is equal to or less than a second predetermined distance value.

[0040] In some embodiments, a first predetermined distance value is greater than a second predetermined distance value. The control unit is configured to use communication signals to transmit data only when the distance is less than the second predetermined distance value.

[0041] In some embodiments, when the distance is equal to or less than a second predetermined distance, the control unit is configured to decode communication signals and thereby transmit data, for example via a near-field communication link and / or a pad-to-pad link.

[0042] In some embodiments, when the distance is greater than a second predetermined distance, the control unit receives communication signals via a wireless communication unit but does not transmit data.

[0043] For example, when the distance is equal to or less than a second predetermined distance, a handshake can be performed between these units to establish data transmission. This handshake is achieved, for example, by polling communication signals between these units. However, this polling does not transmit data.

[0044] Beyond a second predetermined distance, the communication signal is used only to determine the relative position. Furthermore, beyond the second predetermined distance, the communication signal can also be used for polling (i.e., only for determining the relative position and polling), without transmitting data. For example, thus, the communication signal can be used to determine the relative position at distances where its signal strength is insufficient for data transmission, but its phase value can still be detected, for example, by polling.

[0045] In some embodiments, the control unit is configured to use the communication signal to detect relative position even when the distance is equal to or less than a second predetermined distance value. In other words, when the distance is equal to or less than the second predetermined distance, the communication signal is used for both data transmission and determining relative position.

[0046] For example, at long distances, communication signals may attenuate, making reliable data transmission impossible or prone to errors. At such distances (e.g., a first predetermined distance value), the control unit is configured to detect relative position using communication signals, while at appropriately closer distances (e.g., equal to or less than a second predetermined distance value), the control unit is configured to transmit data. When equal to or greater than the first predetermined distance value, the control unit is configured to detect (particularly by comparing the relative phase between antennas) the orientation of the second unit relative to the first unit. In addition to data transmission, the control unit is also configured to further perform relative position detection when equal to or less than the second predetermined distance value.

[0047] Furthermore, the control unit is configured to control the pad to wirelessly transmit and / or receive power when the distance is equal to or less than a third predetermined distance value, wherein the third predetermined distance value is less than a second predetermined distance value. Exemplarily, the third predetermined distance value is the distance within which the control unit determines that alignment has been achieved.

[0048] In some embodiments, the pad includes one or more coils for power transmission and / or reception. In particular, these coils are separate from the antenna of the wireless communication unit.

[0049] Advantageously, the control unit is configured to use on / off keying modulation to modulate communication signals, particularly for data transmission, i.e., for encoding communication signals. Preferably, other types of modulation are also possible, such as frequency modulation.

[0050] In some embodiments, if the communication signal (especially the communication signal used for handshake) is known in advance, a large gain is achieved by using correlation in signal processing, reducing the reliance on low-noise measurements (also known as "correlation amplification").

[0051] In some implementations, the control unit includes a multiplexer, an anti-aliasing filter, and an analog-to-digital converter. This provides a control unit with relatively low-cost components that can provide accurate alignment determination.

[0052] Furthermore, the control unit includes a microcontroller, a transceiver, and an antenna matching circuit connected to the respective main communication antenna for transmitting communication signals between these units (particularly via a communication link, i.e., a pad-to-pad link).

[0053] In some embodiments, the main antenna and / or auxiliary antenna are planar printed circuit board antennas.

[0054] In some embodiments, the control unit is a processor. For example, the control unit includes a microcontroller (“MCU”), CPU, GPU, SoC, ASIC, FPGA, etc. Preferably, the control unit also includes a storage medium.

[0055] The present invention also relates to a power transmission system, including a wireless power system according to any of the examples described above. Furthermore, the power transmission system includes a second unit. In other words, the power transmission system includes a wireless power system having a first unit and a control unit, and further includes a second unit. For example, the first unit of the wireless power system is a secondary unit (receiving side), and the pad of the first unit is a secondary pad configured to wirelessly receive power. The wireless communication unit therein is a secondary wireless communication unit. The second unit is a primary unit, including a primary pad for wireless power transmission and a primary wireless communication unit (transmitting side). In this respect, although exemplarily described herein, it should be understood that, at least for power transmission, the first unit may also be located on the primary side, and the second unit may therefore be located on the secondary side, as well as for the transmission (primary side) and reception (secondary side) of communication signals, and vice versa.

[0056] In some embodiments, the secondary unit (i.e., the first unit of the wireless power system) includes a control unit, particularly when the secondary unit is non-fixed (e.g., mounted in a vehicle).

[0057] In some embodiments, the primary wireless communication unit (i.e., the wireless communication unit of the second unit) includes at least one primary main communication antenna for transmitting and receiving communication signals. Preferably, the primary main communication antenna is configured the same as the main communication antenna of the first unit. The primary wireless communication unit includes at least one (e.g., two to four) primary auxiliary sensing antennas for detecting relative position. The primary auxiliary sensing antennas have the same configuration as the auxiliary sensing antennas of the first unit, i.e., the aforementioned auxiliary sensing antennas. This has the advantage that the primary and secondary sides can be configured substantially equivalently, which is advantageous in terms of signal and power transmission and ease of manufacture. Furthermore, when both the first and second units (i.e., the primary-side unit and the secondary-side unit) are configured for detecting relative position, these units can provide more accurate detection and / or verification of the relative position detected by the corresponding other unit.

[0058] In some examples, the secondary unit is incorporated into electric vehicles, particularly industrial electric vehicles. The primary unit is typically wall-mounted or floor-standing.

[0059] The present invention also relates to a vehicle, particularly an electric vehicle, which includes or is incorporated in a power transmission system according to any of the above examples.

[0060] In some embodiments, the electric vehicle is an automated guided vehicle (AGV) that includes a wireless power system according to any of the examples above. The AGV includes a control unit configured to automatically (i.e., at least largely without user input) guide the AGV to align with the primary and secondary units to improve charging efficiency. Preferably, the AGV includes a secondary unit, i.e., primarily configured to receive power.

[0061] In some embodiments, the control unit of the AGV is a control unit of a wireless power system. The control unit of the AGV is configured to receive communication signals via a wireless communication unit, detect at least one phase value of the communication signal transmitted by the primary unit, and determine the relative position of the AGV with respect to the primary unit (i.e., the second unit).

[0062] Advantageously, the AGV's control unit is also configured to control the AGV, such as the AGV's drive unit (i.e., motor, wheels, etc.), to move the AGV according to the determined relative position in order to reduce (especially minimize) the distance to the second unit.

[0063] Furthermore, the AGV's control unit is configured to enable wireless power transmission, particularly wireless charging of the AGV's battery, once the vehicle is deemed to be aligned with the second unit (especially once the distance based on the relative position is less than a predetermined threshold (e.g., less than a third predetermined distance)).

[0064] Specifically, the AGV's control unit is configured to determine the AGV's relative position once and move the AGV accordingly. This has the advantage of requiring less computational power from the AGV's control unit. In an alternative embodiment, the AGV's control unit is configured to continuously, for example, every few seconds, i.e., 2 seconds, 5 seconds, or 10 seconds, detect the relative position and move the AGV accordingly. This improves alignment accuracy and, in particular, provides redundant measurements that can be used to verify the determination.

[0065] The above explanation of AGVs can be combined with the above explanation of wireless power systems.

[0066] Thus, the present invention realizes an electric vehicle, particularly an AGV, which can be advantageously guided or advantageously autonomously guided to a primary unit in a high-precision and efficient manner, thereby achieving more efficient charging, faster charging speed and greater passenger comfort.

[0067] In some embodiments, the power transmission system includes a wireless power system and the aforementioned AGV. The control unit of the wireless power system is located within the AGV. Alternatively, the control unit of the wireless power system in the power transmission system is located outside the AGV and communicates with the control unit of the AGV via communication signals, enabling the control unit of the AGV to appropriately guide the AGV to a secondary unit.

[0068] The present invention also relates to a method for aligning an AGV with a primary unit (second unit) according to the above-described method of the control unit of the AGV.

[0069] Through the above embodiments, the present invention provides a wireless power system capable of accurately detecting its position relative to a second unit. The present invention also provides a power transmission system in which a first unit is capable of accurately detecting its position relative to a second unit of the power transmission system.

[0070] The above embodiments and configurations can be combined. The explanations regarding the primary side and / or secondary side should be understood as being interchangeable in principle. Furthermore, the terms "primary side" and "secondary side" should be understood as being interchangeable with "power transmitting side" and "power receiving side," respectively. Attached Figure Description

[0071] Figure 1 shows a top view of the power transmission system according to a first embodiment of the present invention in a vertical installation orientation;

[0072] Figure 2 shows a side view of the wireless power system of the power transmission system according to a first embodiment of the present invention;

[0073] Figure 3 shows a schematic overlay diagram of the power transmission system and phase diagram used to explain the first embodiment of the present invention;

[0074] Figure 4 shows another schematic overlay diagram of the power transmission system and phase diagram used to explain the first embodiment of the present invention;

[0075] Figure 5 shows a block diagram illustrating the detailed configuration of a power transmission system according to a first embodiment of the present invention;

[0076] Figure 6 shows a block diagram illustrating the detailed configuration of a power transmission system according to a second embodiment of the present invention;

[0077] Figure 7 shows a block diagram illustrating the detailed configuration of a power transmission system according to a third embodiment of the present invention;

[0078] Figure 8 shows a schematic diagram of an electric vehicle according to the present invention. Detailed Implementation

[0079] Further details, advantages, and features of the embodiments of the present invention will be described in detail with reference to the accompanying drawings. The first embodiment of the present invention will be described with reference to Figures 1 to 5. Figure 1 shows a top view of a power transmission system 100 according to a first embodiment of the present invention in a vertical mounting orientation. Figure 2 shows a detailed side view of the wireless power system 1 of the power transmission system 100 according to a first embodiment of the present invention. Figures 3 and 4 both show schematic overlay diagrams illustrating the power transmission system 100 and phase diagrams according to the first embodiment of the present invention. Figure 5 shows a block diagram illustrating the function of the power transmission system 100 according to the first embodiment of the present invention.

[0080] As shown in Figure 1, the power transmission system 100 of this embodiment includes a wireless power system 1 and a second unit 10 located outside the wireless power system 1.

[0081] Specifically, the power transmission system 100 shown in FIG1 includes a first unit 20 as the secondary side (receiving side) and a second unit 10 as the primary side (transmitting side) for wireless power transmission (transmitting and receiving).

[0082] However, as shown in Figure 2, the present invention is not strictly limited thereto, and should be understood as being able to be implemented as a wireless power system 1 that preferably includes only one side (i.e., the primary or secondary). In the power transmission system 100 of Figure 1, the wireless power system 1 is implemented as the secondary side (receiving side), its first unit 20 being referred to below as "secondary unit 20", and the second unit 10 of the power transmission system 100 is implemented as the primary side (transmitting side), being referred to below as "primary unit 10" as an example.

[0083] Regarding the power transmission system 100 of Figure 1, its wireless power system 1 includes a secondary unit 20, which contains a pad 21 (hereinafter referred to as "secondary pad 21") configured to wirelessly transmit power. The primary unit 10 also includes a pad 11 (hereinafter referred to as "primary pad 11") configured to wirelessly transmit or receive power from the secondary pad 21. Each of the primary pad 11 and the secondary pad 21 includes a coil (not shown) that is inductively and / or capacitively coupled to each other to wirelessly transmit electromagnetic energy.

[0084] For example, the wireless power system 1 is configured to perform high-power wireless charging in the range of 50kHz to 80kHz with a wattage of 1kW to 75kW.

[0085] As shown in the top view of Figure 1, the primary unit 10 is wall-mounted. In an optional embodiment, the primary unit 10 can be floor-mounted.

[0086] The primary unit 10 also includes a primary wireless communication unit 12. The secondary unit 20 also includes a secondary wireless communication unit 22. The primary and secondary wireless communication units 12 and 22 are shown schematically in FIG1. ​​The secondary wireless communication unit 22 will be described in detail below with reference to FIG2.

[0087] The primary and secondary wireless communication units 12 and 22 are configured to exchange information via near-field communication. In other words, the primary and secondary wireless communication units 12 and 22 are configured to provide a near-field communication link as a communication signal. This is specifically referred to as a "pad-to-pad link" (also known as a "PPL"). In this embodiment, the communication signal is encoded by on / off keyed modulation. However, the invention is not limited to this modulation method, and alternative known modulation types can be implemented.

[0088] In this embodiment, the communication signal includes (i.e., is encoded) information such as device identification and power transmission requirements for controlling power transmission via the pad. For example, a large number of wireless power systems 1 may be provided, such as in industrial buildings, which are alternately powered by the primary unit 10, and therefore include identification information and / or their respective power supply requirement information.

[0089] Furthermore, the wireless power system 1 includes a control unit 2. In this embodiment, the control unit 2 is connected to the secondary wireless communication unit 22. Additionally, the control unit 2 is preferably connected to the primary wireless communication unit 12 and / or the primary pad 11 and / or the secondary pad 21. Specifically, the control unit 2 is preferably wirelessly connected to any one or more of the aforementioned units.

[0090] Preferably, although not shown, the power transmission system 100 includes a plurality of control units, wherein preferably, each of the primary unit 10 and the secondary unit 20 respectively includes a (primary or secondary) control unit, which is wirelessly connected to the control unit 2. In other words, the control unit 2 in this embodiment is preferably a central control unit 2 for controlling the primary unit 10 and the secondary unit 20. Preferably, the control unit 2 may be included by the primary unit 10 or the secondary unit 20, and is particularly wirelessly connected to other (primary, secondary or central) control units.

[0091] The control unit 2 of the wireless power system 1 is configured to detect the relative position of the wireless power system 1 with respect to the external primary unit 10. This allows for precise alignment between the wireless power system 1 and the primary unit 10 (i.e., the second unit 10).

[0092] The control unit 2 is configured to detect the distance, particularly the three-dimensional distance, between the primary unit 10 and the secondary unit 20. This distance is then used to achieve optimal alignment for power transmission between the primary unit 10 and the secondary unit 20.

[0093] First, we will explain general alignment based on position detection, and then we will explain the detection of relative position.

[0094] As shown in Figure 1, multiple predetermined distances 33, 34, 35, and 36 can be defined from the center point 37 of the primary wireless communication unit 12 and the secondary wireless communication unit 22.

[0095] Based on the distance between the center points 37, the control unit 2 is configured to perform different operating modes:

[0096] When the distance is equal to or less than the first predetermined distance 33, the control unit 2 is configured to detect the relative position of the communication units 12 and 22. Specifically, the control unit 2 is configured to detect only the relative position without transmitting data between the communication units 12 and 22 via communication signals.

[0097] When the distance is equal to or less than the second predetermined distance 34, the control unit 2 is configured to transmit data using communication signals, particularly by establishing a near-field communication link or a pad-to-pad link handshake between communication units 12 and 22. Beyond the second distance 34, the communication link may be insufficient for stable data transmission, and therefore is preferably used only for determining relative position. In addition to determining relative position, the communication signal can be used at least at or above the second distance 34 for polling between the primary unit 10 and the secondary unit 20, for example, for establishing a handshake. In other words, above the second distance 34, the communication signal is not used for data transmission, but only for determining relative position and polling.

[0098] Furthermore, when the distance is equal to or less than the second distance 34, in addition to data transmission, the control unit 2 is also configured to use communication signals to determine the relative position of the primary unit 10 and the secondary unit 20.

[0099] When the distance is equal to or less than a third predetermined distance 35 (which is less than a second predetermined distance 34), the control unit 2 is configured to control the primary pad 11 and / or the secondary pad 12 to perform wireless power transmission, particularly in conjunction with data transmission of communication signals. Furthermore, within this range, the control unit 2 can further detect the relative position to further optimize the positioning of the primary unit 10 and the secondary unit 20.

[0100] Furthermore, when the distance is equal to or less than the fourth predetermined distance 36, the control unit 2 is configured to more accurately determine the relative position of the primary unit 10 and the secondary unit 20, for example, fine alignment. For instance, as will be explained in detail below, when the distance is equal to or less than the first predetermined distance 33, the control unit 2 is configured to determine the distance based on the amplitude value of the communication signal for coarse alignment. Additionally, when the distance is equal to or less than the fourth predetermined distance 36, the control unit 2 is configured to determine the distance based on the phase value of the communication signal for fine alignment.

[0101] Although Figure 1 shows predetermined distances 33-36 distributed along the z-axis for ease of understanding, these distances 33-36 are not necessarily limited to this. Rather, these distances can be understood as three-dimensional distances (distance ranges); or, for example, as two-dimensional distances (distance ranges) in the case where the heights of the primary unit 10 and the secondary unit 20 (i.e., the y-direction in Figure 1) are fixed, especially within the plane defined by the x-axis and z-axis. Of course, this teaching can be readily transferred to the possibility that the primary unit 10 is floor-mounted.

[0102] The detection of relative position will now be described in further detail with reference to Figures 2 to 4. Figure 2 shows in detail the configuration of the wireless power system 1 shown in Figure 1, and Figures 3 and 4 each schematically show the alignment of the wireless power system 1 with the primary unit 10, with superimposed graphs showing the detection values ​​of the control unit 2. However, the following related descriptions may be additionally or alternatively applied to the primary unit 10, and vice versa.

[0103] As shown in Figure 2, the secondary wireless communication unit 22 includes a main communication antenna 23 and four auxiliary sensing antennas 24. The main communication antenna 23 of the secondary wireless communication unit 22 communicates with the main communication antenna 13 of the primary wireless communication unit 12 (not shown in Figure 2, see Figures 5 to 7), particularly for data transmission. The control unit 2 is configured to decode the communication signals received by the main communication antenna 23 of the secondary unit 20. This data transmission occurs particularly when the distance is equal to or less than the aforementioned second predetermined distance 34.

[0104] Preferably, the main communication antenna 23 and the auxiliary sensing antenna 24 are planar printed circuit board antennas.

[0105] The main communication antenna 23 and four auxiliary sensing antennas 24 of the secondary wireless communication unit 22 are configured to receive communication signals transmitted by the main communication antenna 13 of the primary wireless communication unit 12.

[0106] The control unit 2 is configured to detect the relative position of the primary wireless communication unit 12 and the secondary wireless communication unit 22 using the communication signal received by the auxiliary sensing antenna 24 of the secondary wireless communication unit 22. Specifically, the control unit 2 is preferably not configured to decode the communication signal received by the auxiliary sensing antenna 24. Instead, the control unit 2 uses only the signal received by the auxiliary sensing antenna 24 to detect the relative position.

[0107] The detection of this relative position is particularly performed when it is equal to or less than the aforementioned first predetermined distance 33.

[0108] The auxiliary sensing antenna 24 is arranged symmetrically around the main communication antenna 23 of the secondary wireless communication unit 22. The auxiliary sensing antenna 24 is not directly connected to the main communication antenna 23 (see also Figures 5 to 7). However, the auxiliary sensing antenna 24 does not necessarily have to be arranged symmetrically around the main communication antenna 23.

[0109] Each auxiliary sensing antenna 24 of the secondary unit 20 receives communication signals from the main communication antenna 13 of the primary unit 10. Since the auxiliary sensing antennas 24 are located at different positions, the propagation path length of the communication signals received by each auxiliary sensing antenna is different, and therefore their phase values ​​are also different.

[0110] Figures 3 and 4 show the overlap between the primary pad 11 and the primary wireless communication unit 12 on one side and the secondary wireless communication unit 22 and its auxiliary sensing antenna 24 on the other side. For ease of understanding, the main communication antenna 23 of the secondary wireless communication unit 22 is not shown. Furthermore, this view is overlaid with graphs depicting the detection values ​​of the control unit 2. Figure 3 shows the state before final alignment is achieved, while Figure 4 shows the aligned state.

[0111] In this embodiment, the control unit 2 is configured to detect the phase value of the communication signal as shown in Figures 3 and 4. The horizontal axis 38 represents time in seconds, and the vertical axis 39 represents the phase in degrees or radians.

[0112] In this embodiment, the control unit 2 is configured to detect spatial phase relationships as phase values. The control unit 2 detects multiple receptions of communication signals in space via each auxiliary sensing antenna 24 (shown in dashed lines) and compares their phases to determine the distances from each different auxiliary sensing antenna 24 to the primary unit 10.

[0113] Each signal has a phase. And all received signals share a phase offset. Among them, phase It has the following functional dependencies:

[0114] ;

[0115] ;

[0116] ;as well as

[0117] .

[0118] Here, x, y, and z refer to Cartesian coordinates, while the subscripts "s" and "p" refer to secondary unit 20 and primary unit 10, respectively. For example, " "" indicates the distance between the primary unit and the secondary unit in the x-direction.

[0119] In the two-dimensional determination, the phase distance, which is proportional to the distance between the primary unit 10 and the secondary unit 20, can be determined by subtraction operation performed by the control unit 2:

[0120] ;as well as

[0121] .

[0122] In this process, the shared phase shifts of all phases are canceled out, so that only the corresponding phase shifts caused by the different propagation paths of the communication signal to each auxiliary sensing antenna 24 are retained. .

[0123] As shown in the comparison of Figures 3 and 4, the phase shift between multiple receptions This depends on the corresponding relative distance to the primary unit 10 (especially its main communication antenna 23). Therefore, by calculating the spatial phase relationship, the control unit 2 can determine which auxiliary sensing antenna 24 is closer to the primary unit 10, thereby determining its position relative to the primary unit 10.

[0124] As shown in Figure 4, when the phase shift between multiple receptions When the phase shift is zero, the control unit 2 considers the alignment complete because the calculated distance between each auxiliary sensing antenna 24 and the primary unit 10 is equal. It should be understood that, in addition to the phase shift being zero between multiple receptions, or alternatively, a threshold can be used to determine the achieved alignment.

[0125] As can be seen from the above, the control unit 2 is not limited to detecting spatial phase relationships. In other examples, especially when the wireless power system 1 moves relative to the primary unit 10, multiple receptions of communication signals at different time points can be detected as temporal phase relationships, particularly by means of one or more antennas 23, 24. This example is preferably carried out without the auxiliary sensing antenna 24, and preferably only the main communication antenna 23 of the secondary unit 20 is used.

[0126] For example, control unit 2 is configured to calculate the phase difference between the first and second receptions of a communication signal, where the second reception occurs later than the first. This can be understood in principle as follows: control unit 2 calculates the phase difference between two simultaneous receptions, each of the auxiliary sensing antennas 24 being spatially separated, as described in the spatial phase relationship section above.

[0127] Then, the control unit 2 preferably calculates at least one additional phase difference, such as the phase difference between the second and third receptions, and is configured to compare these two calculated phase differences as changes over time. By comparing at least two such calculated phase differences as changes over time with predetermined or received relative movement information, the control unit 2 is configured to determine the time-varying distance between the wireless power system 1 and the primary unit 10. Thus, the control unit 2 can determine whether relative movement causes the relative distance to increase or decrease over time, thereby indicating alignment. However, calculating the change over time is not strictly necessary, but is preferred. Alternatively or otherwise, using only the phase difference over time (e.g., only between two receptions), the mathematical sign of the phase difference (i.e., positive or negative) can indicate whether the relative distance increases or decreases during the time between two receptions, and thus can also be used for alignment.

[0128] Therefore, in order to align, the control unit 2 is configured to output values ​​to the main unit 10 indicating the direction (x, y, z coordinates) and distance relative to the primary unit 10.

[0129] In another example, the control unit 2 is also configured to detect the signal strength of the communication signal, especially the maximum amplitude and / or the maximum peak-to-peak value, and to determine the relative position of the wireless power system 1 and the first unit 10 based on the detected signal strength and the detected phase value.

[0130] Among them, the auxiliary sensing antenna 24 receives the amplitude. , , and Control unit 2 is configured to compare these amplitudes and determine the relative positions using trilateration, wherein:

[0131] ;

[0132] ;

[0133] ;as well as

[0134] .

[0135] Where x, y, and z refer to Cartesian coordinates, and the subscripts "s" and "p" refer to the secondary unit 20 and primary unit 10, respectively. For example, " "" indicates the distance between primary unit 10 and secondary unit 20 in the x direction.

[0136] Since the position of the primary unit 10 is preferably known or predetermined, especially when the primary unit 10 is wall-mounted or floor-mounted, the commonly used trilateration equation can be solved using at least three measurement amplitudes.

[0137] Furthermore, the control unit 2 can be configured, for example, to calculate the cumulative value of the detected amplitude, in particular the sum. Thus, the control unit 2 is configured to detect the size of the air gap 15 between the primary unit 10 and the secondary unit 20 based on the aforementioned value or sum.

[0138] Phase-based detection can be combined with amplitude-based detection. In some examples, phase-based detection has higher accuracy than amplitude-based detection. Therefore, amplitude-based detection can be used for coarse alignment, for example, at a first predetermined distance 33 or less, while phase-based detection can be used for fine alignment, for example, at a fourth predetermined distance 36 or less.

[0139] In this embodiment, the frequency of the communication signal is 13.56 MHz, corresponding to a wavelength of 22.1 m. The primary pad 11 and secondary pad 21 preferably contain ferrite material. This ferrite acts as a magnetic conductor, guiding most of the magnetic flux of the communication signal. Due to its high permeability and high dielectric constant, the velocity factor within the ferrite material is very small, reducing the wavelength to approximately 0.7 m. Therefore, in this embodiment, the accuracy of relative position detection is greatly improved, and the offset between the primary unit 10 and the secondary unit 20 can be accurately mapped to a phase shift of -180° to +180° (the phase shift between the extreme values ​​of the physical offset for the same communication signal).

[0140] The device configuration of the wireless communication units 12 and 22 will now be described with reference to the functional block diagram in Figure 5.

[0141] As described above, the power transmission system 100 includes both the wireless power system 1 and the second unit 10, which is here designated as the primary unit 10.

[0142] The primary unit 10 includes a main communication antenna 13 configured to transmit communication signals 32. For ease of understanding, the secondary wireless communication unit 22, i.e., the main communication antenna 23 of the secondary wireless communication unit 22 of the wireless power system 1, is omitted.

[0143] The secondary wireless communication unit 22 includes four auxiliary sensing antennas 24. Furthermore, the secondary wireless communication unit 22 includes four amplifier units 25, one for each auxiliary sensing antenna 24. The amplifier units 25 are configured to amplify the communication signal 32 received by the corresponding auxiliary sensing antenna 24.

[0144] The secondary wireless communication unit 22 includes two analog phase detectors 40, each of which detects the relative phase between two (amplified) receptions of the communication signal 32 by the corresponding auxiliary sensing antenna 24. This configuration is suitable for two-dimensional relative position detection and can be adapted accordingly for three-dimensional relative position detection, for example by adding auxiliary sensing antennas 24 and phase detectors 40.

[0145] The secondary wireless communication unit 22 also includes a microcontroller (MCU) 27, which contains two analog-to-digital converters 30 for converting the received communication signals.

[0146] The microcontroller 27 of the secondary unit 20 is particularly connected to or included in the control unit 2 to perform the aforementioned relative position determination.

[0147] Preferably, in this embodiment of FIG5, the phase detector 40 is asynchronous and outputs a DC signal. Therefore, the sampling rate of the analog-to-digital converter 30 is preferably within a range perceptible to humans, such as about 60 Hz, but can typically be selected based on the specifications and cost of the electronics.

[0148] Figure 6 shows a block diagram for explaining the detailed configuration of the power transmission system 100 according to a second embodiment of the present invention.

[0149] In this embodiment, the secondary wireless communication unit 22 includes four anti-aliasing filters 41, which are respectively connected to the amplifier 25 and the analog-to-digital converter 30.

[0150] The anti-aliasing filter 41 directly samples the low-pass filtered communication signal 32 at high speed, and combined with the fast Fourier transform in MCU27, provides accurate and fast phase value detection.

[0151] Figure 7 shows another block diagram for explaining the detailed configuration of the power transmission system 100 according to a third embodiment of the present invention.

[0152] In this embodiment, the secondary wireless communication unit 22 includes a multiplexer 31 that connects each auxiliary sensing antenna 24 to a single amplifier 25. The amplifier 25 outputs to a single anti-aliasing filter 41, which is connected to the analog-to-digital converter 30 of the MCU 27. This achieves an efficient and low-cost configuration for accurate and rapid relative position determination and alignment.

[0153] In the embodiments of Figures 6 and 7, the sampling rate is preferably 2×f, where "f" is the frequency of the wireless communication signal. For example, for a near-field communication link, the sampling rate is 2×13.56MHz. In some embodiments, the sampling rate can be twice the bandwidth of the anti-aliasing filter 41, because the wireless communication signal may alias to lower frequencies, but this will not cause ambiguity because such lower frequencies will be filtered out (also known as "undersampling").

[0154] Figure 8 shows a schematic diagram of the electric vehicle 101 of the present invention.

[0155] In this embodiment, the electric vehicle 101 includes a power transmission system 100 according to the first, second, or third embodiment of the present invention.

[0156] In this implementation example, the electric vehicle 101 includes a wireless power system 1, specifically including a first unit (secondary unit 20) and a control unit 2 of the wireless power system 1 according to the above embodiments.

[0157] For example, electric vehicle 101 is an automated guided vehicle (AGV), especially an automated forklift. Alternatively, electric vehicle 101 can be an implementation of an automated robot, especially a wireless power system 1 for a warehousing facility. In this implementation, the electric vehicle (automatically or manually driven) retrieves and / or places stored items within the facility. Alternatively, electric vehicle 101 can be an electric car, etc.

[0158] The second unit (i.e., primary unit 10) of the power transmission system 100 is particularly wall-mounted. The electric vehicle 101 includes a control unit 2 and a secondary unit 20 for a wireless power system. Furthermore, the electric vehicle 101 includes a battery unit 102, which is charged via wireless power transmission from the primary unit 10.

[0159] Alternatively, the primary unit 10 can be floor-mounted. The orientation or mounting position of the secondary unit 20 can vary depending on the mounting position of the primary unit 10. For example, if the primary unit 10 is floor-mounted, the secondary unit 20 can be mounted on or below the floor of the electric vehicle 101.

[0160] Using the aforementioned wireless power system 1 and power transmission system 100, the relative positions of the primary unit 10 mounted on the wall and the secondary unit 20 mounted on the electric vehicle 101 can be detected. Furthermore, using the detection results, especially through the control unit 2, the electric vehicle 101 can be controlled efficiently and easily to ensure that the secondary unit 20 is precisely aligned with the primary unit 10 in three-dimensional space, thereby achieving efficient wireless power transmission.

[0161] Specifically, as described above, the control unit 2 is configured to determine the relative position of the electric vehicle 101 based on at least one phase value of the communication signal 32 sent by the primary unit 10, and to determine the relative position of the vehicle 101 with respect to the primary unit 10.

[0162] Advantageously, the control unit 2 of the vehicle 101 is also configured to control the vehicle 101, especially the drive unit of the vehicle 101 (i.e., motor, wheels, etc.), to move the vehicle 101 according to the determined relative position, thereby reducing, in particular minimizing, the distance to the primary unit 10, i.e., reducing the air gap 15.

[0163] More preferably, the control unit 2 of the vehicle 101 is configured to enable wireless power transmission, particularly wireless charging of the battery unit 102, once the vehicle 101 is considered aligned with the primary unit 10, especially once the air gap 15 based on the determined relative position is less than a predetermined threshold (e.g., less than the aforementioned third predetermined distance 35).

[0164] Specifically, the control unit 2 of vehicle 101 is configured to determine the relative position of vehicle 101 once and move vehicle 101 according to the aforementioned relative position. This has the advantage that the control unit 2 of vehicle 101 requires less computational power. In an advantageous variation of this embodiment, the control unit 2 of vehicle 101 is configured to continuously, for example every few seconds, i.e., every 2 seconds, 5 seconds, or 10 seconds, detect the relative position and move vehicle 101 accordingly. This improves alignment accuracy and, in particular, provides redundant measurements that can be used to verify the determined position.

[0165] In another possible implementation, the electric vehicle 101 can also be an elevator. The primary unit 10 is preferably installed at the bottom of the elevator shaft, while the secondary unit 20 is preferably installed at or below the elevator floor. In other examples of implementations, the primary unit 10 is preferably installed on the elevator wall, and the secondary unit 20 is preferably installed on the elevator shaft wall, for example, on the floor where the elevator typically spends the most time (or the ground floor). Advantageously, by replacing the cables connecting the elevator electronics with the wireless power system 1 of the present invention, wear and tear on the cables can be prevented.

[0166] The foregoing embodiments can be combined appropriately. Furthermore, the designations for primary / transmitter side and secondary / receiver side can be interchanged appropriately.

[0167] In addition to the foregoing written description, reference is made explicitly to Figures 1 through 8, which show in detail the logic circuit diagrams and configuration examples of the present invention.

Claims

1. A wireless power system (1), comprising: The first unit (10, 20) includes a pad (11, 21) configured to wirelessly transmit or receive power and a wireless communication unit (12, 22); and a control unit (2); wherein the pad (11, 21) is configured to wirelessly transmit power to or receive power from the second unit (10, 20), the wireless communication unit (12, 22) is configured to receive a communication signal (32) from the second unit (10, 20), and wherein the control unit (2) is configured to detect at least one phase value of the communication signal (32) and determine the relative position of the wireless communication unit (12, 22) and the second unit (10, 20) based on the detected phase value.

2. The wireless power system (1) according to claim 1, wherein, The control unit (2) is configured to calculate the phase relationship between multiple receptions of the communication signal (32) as the phase value, and to determine the relative position based on the calculated phase relationship, wherein the phase relationship is a phase difference.

3. The wireless power system (1) according to claim 2, wherein, The control unit (2) is configured to calculate the time phase relationship between multiple receptions at different time points as the phase relationship, wherein the different time points are during the relative movement of the wireless communication unit (12, 22) and the second unit (10, 22).

4. The wireless power system (1) according to claim 3, wherein the control unit (2) is configured to calculate at least two time phase relationships between two receptions at different time points, and to calculate the time phase relationships as a function of time.

5. The wireless power system (1) according to claim 4, wherein, The control unit (2) is configured to compare the time-varying changes with input and / or predetermined movement information from the wireless communication unit (12, 22), the movement information including the amount of movement and / or the direction of movement.

6. The wireless power system (1) according to claim 1, wherein, The wireless communication unit (12, 22) includes at least one main communication antenna (13, 23) for transmitting and receiving the communication signal (32), and the wireless communication unit (12, 22) includes at least one or two to four auxiliary sensing antennas (24) for detecting the relative position.

7. The wireless power system (1) according to claim 6, wherein, The control unit (2) is configured to calculate the spatial phase relationship between multiple receptions of the communication signal (32) on different antennas in at least one main communication antenna (13, 23) and at least one auxiliary sensing antenna (24) as the phase value, and determine the relative position based on the calculated spatial phase relationship.

8. The wireless power system (1) according to claim 7, wherein, The control unit (2) is configured to calculate the difference between the phases of the multiple receptions as the spatial phase relationship, and to determine the distance between the antennas and the second unit (10, 20) corresponding to different phases.

9. The wireless power system (1) according to claim 6, wherein, Multiple auxiliary sensing antennas (24) are arranged symmetrically around the main communication antenna (23).

10. The wireless power system (1) according to claim 1, wherein, The control unit (2) is also configured to detect the signal strength of the communication signal (32) and determine the relative position of the wireless communication unit (12, 22) and the second unit (10, 20) based on the detected signal strength and the detected phase value, wherein the signal strength is the maximum amplitude and / or the maximum peak-to-peak value.

11. The wireless power system (1) according to claim 1, wherein the wireless communication unit (12, 22) is separated from the second unit (10, 20) by a certain distance, and the control unit (2) is configured to: detect the relative position using the communication signal (32) when the distance is equal to or less than a first predetermined distance value; and / or transmit data using the communication signal (32) when the distance is equal to or less than a second predetermined distance value; wherein, The first predetermined distance value is greater than the second predetermined distance value.

12. The wireless power system (1) according to claim 11, wherein, The control unit (2) is configured to use the communication signal to transmit data only when the distance is less than the second predetermined distance value.

13. The wireless power system (1) according to claim 11, wherein, The control unit (2) is configured to control the pad (11, 21) to wirelessly transmit and / or receive power when the distance is equal to or less than a third predetermined distance value, wherein the third predetermined distance value is less than the second predetermined distance value.

14. A power transmission system (100) comprising a wireless power system (1) according to any one of the preceding claims and the second unit (10, 20), wherein, The first unit (10, 20) is a secondary unit (20), the pad (11, 21) is a secondary pad (21) configured to wirelessly receive power, and the wireless communication unit (12, 22) is a secondary wireless communication unit (22). The second unit (10, 20) is a primary unit (10), which includes a primary pad (11) for wireless power transmission and a primary wireless communication unit (12).

15. The power transmission system (100) according to claim 14, wherein, The primary wireless communication unit (12) includes at least one primary main communication antenna (23) for transmitting and receiving the communication signal (32), and wherein the primary wireless communication unit (12) includes at least one or two to four primary auxiliary sensing antennas (24) for detecting the relative position.

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