Coil structure for transmitting three-phase wireless power, and wireless power transmission apparatus and method using same

Abstract

A coil structure for transmitting three-phase wireless power is disclosed. The coil structure includes: a first coil element corresponding to a first phase and arranged to surround a first region; and a second coil element corresponding to the first phase and arranged to surround a second region adjacent to the first region. The first coil element and the second coil element are connected to the same power source, and the first coil element and the second coil element branch from a branch point such that the first coil element is arranged around the first region and the second coil element is arranged around the second region.

Description

Technical Field

[0001] The present disclosure relates to a wireless power transmission device / pad and a wireless power receiving device / pad for wireless power transmission (WPT), and a wireless power transmission method using the wireless power transmission device / pad and the wireless power receiving device / pad. More specifically, the present disclosure relates to a coil structure for improving power transmission efficiency in wireless power transmission, and a wireless power transmission method using the coil structure. Background Art

[0002] An electric vehicle (EV) is driven by an electric motor through electricity stored in a battery, and compared to a conventional gasoline engine vehicle, the electric vehicle generates less pollution such as exhaust gas and noise, and has advantages of fewer malfunctions, longer life, and simplified driving operation.

[0003] EVs can be classified into hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and electric vehicles (EVs) based on the driving power source. HEVs have an engine as a main power source and a motor as an auxiliary power source. PHEVs have a motor and a battery as a main power source and an engine used when the battery is discharged. EVs have a motor but no engine.

[0004] An electric vehicle charging system may be defined as a system for charging a battery installed in an electric vehicle using power obtained from a commercial power grid or stored in an energy storage device. Such an electric vehicle charging system may have various forms depending on the type of electric vehicle. For example, an electric vehicle charging system may include a conductive charging system using a cable or a contactless wireless power transmission system.

[0005] During a charging session, a receiving pad of a vehicle assembly (VA) mounted on an electric vehicle can form an inductive resonant coupling with a transmitting pad of a ground assembly (GA) mounted at a charging station or charging point, and the battery of the EV can be charged using power transmitted from the ground assembly via the inductive resonant coupling.

[0006] Meanwhile, the structure of the transmission pad and the receiving pad may be a key factor for ensuring high power transmission efficiency in a magnetic resonance type wireless power transmission system. Specifically, in a typical configuration of a transmission pad or a receiving pad including a ferrite structure for facilitating wireless power transmission and a coil wound around the ferrite structure, the power transmission efficiency may vary depending on the ferrite structure and / or the coil structure.

[0007] Therefore, there is a need for a core structure that can improve the power transmission efficiency in a wireless power transmission system. Summary of the invention

[0008] Technical issues

[0009] Generally, the structure and form of the coil of wireless power transmission for electric vehicle charging are determined in terms of its size and the number of induction phases (i.e., single phase or three phases) according to the desired charging capacity. In the wireless power transmission system, the ground component (GA) system is prepared to match the vehicle component (VA) system, i.e., compatible with the form and charging capacity of the vehicle component system.

[0010] The single-loop coil commonly used as a single-phase induction coil for low-capacity wireless charging exhibits high ripple current at high power levels and is therefore not suitable for high-capacity power transmission systems.

[0011] In order to solve the above problems, an object of the present disclosure is to provide a novel coil structure that can be applied to a three-phase inductive wireless power transmission system with high input power and exhibiting low ripple current.

[0012] Another object of the present disclosure is to provide a coil structure, wherein corresponding three-phase coils are arranged in a stacked configuration, and when a three-phase input voltage with a phase difference of 120 degrees is applied to the three-phase coils, the magnetic fields generated by the three-phase coils do not cancel each other and form a large composite magnetic field to ensure efficient power transmission.

[0013] Another object of the present disclosure is to provide a coil structure that improves the phase symmetry of current and magnetic field distribution between coil elements within corresponding three-phase coils to form a stable magnetic field distribution.

[0014] Another object of the present disclosure is to provide a wireless power transmission (WPT) device and system having an optimized arrangement of a novel magnetic coil structure and exhibiting improved power transmission efficiency.

[0015] Technical Solution

[0016] According to one aspect of an exemplary embodiment for achieving the purpose, a coil structure configured for three-phase wireless power transmission (WPT) may include: a first phase coil corresponding to a first phase. The first phase coil includes: a first coil element corresponding to the first phase and arranged to surround a first space; and a second coil element corresponding to the first phase and arranged to surround a second space adjacent to the first space.

[0017] The first coil element and the second coil element are connected to the same power source. The first coil element and the second coil element are branched at a branch point, and the first coil element is arranged to surround the first space, and the second coil element is arranged to surround the second space.

[0018] The coil structure may further include: a second phase coil corresponding to the second phase; and a third phase coil corresponding to the third phase. The first phase coil, the second phase coil, and the third phase coil may be arranged to share a center point and have an angle difference of 120 degrees from each other.

[0019] The second phase coil may include two coil elements corresponding to the second phase and arranged to surround corresponding spaces adjacent to each other.

[0020] The third phase coil may include two coil elements corresponding to the third phase, each of the two coil elements being arranged to surround a corresponding space adjacent to each other.

[0021] The first coil element and the second coil element in each phase coil of the three-phase coil may be connected to the same power source through a common port.

[0022] The first coil element and the second coil element in each phase coil of the three-phase coil may share a common feeder line portion between the first space and the second space.

[0023] The first coil element and the second coil element may be arranged symmetrically with respect to the common feeder portion.

[0024] The first magnetic field formed in the first space may be opposite in direction to the second magnetic field formed in the second space.

[0025] According to another aspect of the exemplary embodiment, a three-phase wireless power transmission device configured to wirelessly transmit three-phase power to a receiving pad including a secondary coil includes: a first phase coil corresponding to a first phase; a second phase coil corresponding to a second phase; a third phase coil corresponding to a third phase; and a power supply circuit configured to supply power to the first phase coil, the second phase coil, and the third phase coil.

[0026] Each of the first phase coil, the second phase coil, and the third phase coil includes: a first coil element corresponding to the corresponding phase and arranged to surround a first space; and a second coil element corresponding to the corresponding phase and arranged to surround a second space adjacent to the first space.

[0027] In each of the first phase coil, the second phase coil, and the third phase coil, the first coil element and the second coil element are connected to the same power source, and are respectively branched at branch points and arranged to surround the first space and the second space, respectively.

[0028] The first phase coil, the second phase coil, and the third phase coil may be arranged to share a center point and have an angle difference of 120 degrees from each other.

[0029] In each of the first phase coil, the second phase coil, and the third phase coil, the first coil element and the second coil element may be connected to the same power source through a common port.

[0030] In each of the first phase coil, the second phase coil, and the third phase coil, the first coil element and the second coil element may share a common feeder portion between the first space and the second space and be arranged symmetrically with respect to the common feeder portion.

[0031] In each of the first phase coil, the second phase coil, and the third phase coil, a first magnetic field formed in the first space may be opposite in direction to a second magnetic field formed in the second space.

[0032] According to another aspect of an exemplary embodiment, a method for wirelessly transmitting power from a transmission pad including a three-phase primary coil to a receiving pad including a three-phase secondary coil includes: providing a three-phase primary coil, each phase primary coil respectively including: a first coil element, which is associated with the corresponding phase and is arranged to surround a first space; a second coil element, which is associated with the corresponding phase and is arranged to surround a second space adjacent to the first space; positioning a common center point of the three-phase secondary coils within a predetermined offset range from the common center point of the three-phase primary coils; and supplying three-phase input power to the three-phase primary coil and allowing the three-phase input power to be wirelessly transmitted to the three-phase secondary coil.

[0033] When a three-phase primary coil is provided, the first coil element and the second coil element in each of the three-phase primary coils may be connected to the same power source. The first coil element and the second coil element may branch at a branch point and be arranged to surround the first space and the second space, respectively.

[0034] When a three-phase primary coil is provided, the first coil element and the second coil element in each of the three-phase primary coils may be connected to the same power source through a common port.

[0035] When three-phase primary coils are provided, the first coil element and the second coil element in each of the three-phase primary coils may share a common feeder portion between the first space and the second space and be arranged symmetrically with respect to the common feeder portion.

[0036] When three-phase primary coils are provided, in each of the three-phase primary coils, a first magnetic field formed in the first space may be opposite in direction to a second magnetic field formed in the second space.

[0037] Beneficial Effects

[0038] According to an exemplary embodiment of the present disclosure, there is provided a novel coil structure applicable to a three-phase inductive wireless power transmission system having high input power and exhibiting low ripple current.

[0039] In the coil structure according to the exemplary embodiment of the present disclosure, the three-phase coils corresponding to the respective phases are arranged in a stacked configuration. When a three-phase input voltage having a phase difference of 120 degrees is applied to the three-phase coils, the magnetic fields generated by the three-phase coils 300 do not cancel each other and form a large composite magnetic field to ensure efficient power transmission.

[0040] According to an exemplary embodiment of the present disclosure, a coil structure that improves the phase symmetry of current and magnetic field distribution between coil elements within corresponding three-phase coils and forms a stable magnetic field distribution may be implemented.

[0041] According to an exemplary embodiment of the present disclosure, there is provided a wireless power transmission (WPT) device and system having an optimized arrangement of a novel magnetic coil structure and exhibiting improved power transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a schematic diagram of a wireless power transmission system to which an exemplary embodiment of the present disclosure may be applied;

[0043] Figure 2 is a circuit diagram of an equivalent circuit of a wireless charging circuit for an electric vehicle according to an exemplary embodiment of the present disclosure;

[0044] Figure 3 An equivalent circuit of a single-phase to single-phase wireless power transmission (WPT) system according to an exemplary embodiment of the present disclosure is shown;

[0045] Figure 4 are conceptual cross-sectional and front views of a transmission pad according to an exemplary embodiment of the present disclosure;

[0046] Figure 5 An equivalent circuit of a three-phase to three-phase WPT system according to an exemplary embodiment of the present disclosure is shown;

[0047] Figure 6 is a conceptual diagram showing a coil structure for three-phase wireless power transmission according to an exemplary embodiment of the present disclosure;

[0048] Figure 7 It is shown Figure 6 Circuit diagram of the equivalent circuit of the coil structure;

[0049] Figure 8 is a flowchart conceptually illustrating a wireless power transmission method according to another exemplary embodiment of the present disclosure; and

[0050] Fig. 9 is a block diagram illustrating a general configuration of hardware included in or associated with a wireless power transmission pad and / or a wireless power reception pad to control a sequence for wireless power transmission. DETAILED DESCRIPTION

[0051] In order to more clearly understand the features and advantages of the present disclosure, the exemplary embodiments of the present disclosure will be described in detail with reference to the attached drawings. However, it should be understood that the present disclosure is not limited to the specific embodiments disclosed herein, but includes all modifications, equivalents and replacements that fall within the spirit and scope of the present disclosure. In the accompanying drawings, similar or corresponding parts can be represented by the same or similar reference numerals.

[0052] Terms including ordinal numbers (such as "first" and "second") designated in this specification for explaining various components are used to distinguish components from other components, but are not intended to be limited to specific components. For example, a second component may be referred to as a first component, and similarly, a first component may be referred to as a second component without departing from the scope of the present disclosure. As used herein, the term "and / or" may include the presence of one or more associated listed items and any and all combinations of the listed items.

[0053] In the description of the exemplary embodiments of the present disclosure, “at least one of A and B” may mean “at least one of A or B” or “at least one of a combination of one or more of A and B”. Furthermore, in the description of the exemplary embodiments of the present disclosure, “one or more of A and B” may mean “one or more of A or B” or “one or more of a combination of one or more of A and B”.

[0054] When a component is referred to as being "connected" or "coupled" to another component, the component may be directly logically or physically connected or coupled to the other component or indirectly connected or coupled through an intervening object. Conversely, when a component is referred to as being "directly connected" or "directly coupled" to another component, it should be understood that there are no intervening objects between the components. Other words used to describe relationships between elements should be interpreted in a similar manner.

[0055] These terms are used herein only for the purpose of describing specific exemplary embodiments and are not intended to limit the present disclosure. Unless the context clearly dictates otherwise, singular forms also include plural referents. Moreover, the expressions "comprises," "includes," "constructed," and "configured" are used to refer to the presence of a combination of features, quantities, processing steps, operations, elements, or parts, but are not intended to exclude the presence or addition of another feature, quantity, processing step, operation, element, or part.

[0056] Unless otherwise defined, all terms (including technical or scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant documents, and should not be interpreted as having an ideal or overly formal meaning unless explicitly defined in this application.

[0057] Meanwhile, if necessary, one or more conventional components may be included in the configuration of the present disclosure, and such components will be described herein to the extent that the technical concept and concept of the present disclosure are not obscure. However, if the description of conventional components may obscure the technical concept and concept of the present disclosure, the detailed description of these components may be omitted for simplicity.

[0058] The terms used in this disclosure are defined as follows.

[0059] “Electric Vehicle (EV)”: An automobile, as defined in 49 CFR 523.3, intended for highway use, powered by an electric motor that draws electrical current from an on-board energy storage device (such as a battery) that is rechargeable from an off-vehicle power source (such as residential or public electric service or an on-board fuel generator).

[0060] EV may include electric vehicles, electric vehicles, electric road vehicles (ERV), plug-in vehicles (PV), electric drive vehicles (xEV), etc., and xEV may be classified into plug-in full electric vehicles (BEV), battery electric vehicles, plug-in electric vehicles (PEV), hybrid electric vehicles (HEV), hybrid plug-in electric vehicles (HPEV), plug-in hybrid electric vehicles (PHEV), etc.

[0061] “Plug-in Electric Vehicle (PEV)”: An electric vehicle that charges its on-board main battery by connecting to the electrical grid.

[0062] “Plug-in Vehicle (PV)”: An electric vehicle that is rechargeable from Electric Vehicle Supply Equipment (EVSE) via wireless charging without the use of a physical plug or physical outlet.

[0063] “Heavy Duty Vehicle (HD Vehicle)”: Any vehicle with four or more wheels (bus) as defined in 49 CFR 523.6 or 49 CFR 37.3.

[0064] “Light-duty plug-in electric vehicle”: a three- or four-wheeled vehicle that is primarily intended for use on public streets, roads, and highways and has a rated gross vehicle weight of less than 4545 kg and is propelled by an electric motor that draws electric current from a rechargeable battery or other energy device.

[0065] “Wireless Power Charging System (WCS)”: A system for wireless power transfer and control of interactions including operations for alignment and communication between a supply device (or ground component) and an EV device (or vehicle component).

[0066] “Wireless Power Transfer (WPT)”: The transmission of power between a power source such as a utility, grid, energy storage device, fuel cell generator and an EV through a contactless channel such as electromagnetic induction and resonance.

[0067] "Utility": A set of systems that provide electrical energy and include Customer Information System (CIS), Advanced Metering Infrastructure (AMI), rate and revenue systems, etc. Utilities can provide energy to EVs through rate schedules and discrete events. In addition, utilities can provide information related to EV certification, intervals for power consumption measurement, and tariffs.

[0068] “Smart Charging”: A system in which the EVSE and / or EV (including PEV or PHEV) communicate with the grid to optimize the charging rate or discharging rate of the EV by reflecting the capacity or usage charges of the grid.

[0069] “Automatic charging”: The process of automatically performing inductive charging after the vehicle is in the appropriate position corresponding to the main charger component, which can transfer power through conductive charging or inductive charging. Automatic charging can be performed after obtaining the necessary authentication and permissions.

[0070] "Interoperability": A state in which components of a system interact with corresponding components of the system to perform operations targeted by the system. Additionally, information interoperability may refer to the ability of two or more networks, systems, devices, applications, or components to effectively share and easily use information without inconvenience to users.

[0071] "Inductive Charging System": A system that transfers energy from a power source to an EV via a two-part gapped core transformer, wherein the two halves of the transformer (i.e., the primary coil and the secondary coil) are physically separated from each other. In the present disclosure, an inductive charging system may correspond to an EV power transfer system.

[0072] “Inductive Coupler”: A transformer formed by a primary coil in a primary or ground assembly (GA) and a secondary coil in a secondary or vehicle assembly (VA) that allows power transfer with electrical isolation.

[0073] "Inductive Coupling": Magnetic coupling between two coils. One of the two coils may be referred to as the primary coil or GA coil, and the other of the two coils may be referred to as the secondary coil or vehicle component VA coil.

[0074] "Power supply circuit (SPC) or "ground assembly (GA)": a component arranged on the main device or ground assembly or infrastructure side including a primary coil (or GA coil) and other components. Other components may include at least one component for controlling impedance and resonant frequency, ferrite for strengthening the magnetic circuit, and electromagnetic shielding material. For example, the SPC or GA may include a power / frequency conversion unit and an SPC controller (or GA controller) required to be used as a power source for the wireless power charging system, wiring from the power grid, and wiring between each unit, a filtering circuit, and a housing.

[0075] "EV Power Circuit (EVPC)" or "Vehicle Assembly (VA)": An assembly mounted on a vehicle that includes a secondary coil (or VA coil) and other components. Other components may include at least one component for controlling impedance and resonant frequency, ferrite to strengthen the magnetic circuit, and electromagnetic shielding materials. For example, an EVPC or VA may include a power / frequency conversion unit and an EVPC controller (or VA controller) required as a vehicle component of a wireless power charging system, wiring to the vehicle battery, and wiring between each unit, the filter circuit, and the housing.

[0076] The SPC may be referred to as or identified by a ground assembly (GA), etc. Similarly, the EVPC may be referred to as or identified by a vehicle assembly (VA), etc.

[0077] GA may be referred to as a primary device, etc., and VA may be referred to as an EV device, a secondary device, etc.

[0078] GA may be referred to as a supply device, a power supply-side device, or the like, and VA may be referred to as an EV device, an EV-side device, or the like.

[0079] "Primary Device": A device that provides contactless coupling with a secondary device. In other words, the primary device may be a device external to the EV. When the EV receives power, the primary device may operate as a source of power to be transferred. The primary device may include the housing and any covers.

[0080] "Secondary device": a device mounted on an EV that provides contactless coupling with a primary device. In other words, the secondary device may be disposed within the EV. When the EV receives power, the secondary device may transfer power from the primary device to the EV. The secondary device may include the housing and any covers.

[0081] "Power supply electronics" refers to the portion of the SPC or GA that regulates the output power level of the primary coil (or GA coil) based on information from the vehicle. "EV power electronics" refers to the portion of the EVPC or VA that monitors specific on-board parameters during charging and initiates communication with the EVPC or GA to facilitate adjustment of the output power level.

[0082] The power electronics may be referred to as GA electronics, GA controller, or primary device communication controller (PDCC), and the EV power electronics may be referred to as VA electronics, VA controller, or electric vehicle communication controller (EVCC).

[0083] "Magnetic Gap": The vertical distance between the plane of the higher of the top of the Litz wire or the top of the magnetic material in the Primary / GA Coil and the plane of the lower of the bottom of the Litz wire or the bottom of the magnetic material in the Secondary / VA Coil when the two are aligned.

[0084] "Ambient Temperature": The ground-level temperature of the air measured at the subsystem under consideration and out of direct sunlight.

[0085] “Vehicle ground clearance”: the vertical distance between the ground and the lowest part of the vehicle's floor.

[0086] “Vehicle Magnetic Ground Clearance”: The vertical distance between the bottom of the Litz wire or the lower plane of the bottom of the magnetic material in a secondary coil or VA coil mounted on a vehicle and the ground.

[0087] "Secondary Coil Surface Distance" or "VA Coil Magnetic Surface Distance": The distance between the plane closest to the magnetic component surface or conductive component surface and the lower outer surface of the secondary coil or VA coil when mounted. Such distance may include any protective coverings and additional items that may be packaged in the secondary coil or VA coil housing.

[0088] The secondary coil may be referred to as a VA coil, a vehicle coil, or a receiver coil. Similarly, the primary coil may be referred to as a GA coil or a transmission coil.

[0089] “Exposed conductive parts”: Conductive parts of electrical equipment (e.g., electric vehicles) that can be touched and are not normally energized, but may become energized when a fault occurs.

[0090] “Hazardous live parts”: Live parts that can produce harmful electric shock under certain conditions.

[0091] “Live Parts”: Any conductor or conducting part designed to be electrically energized in normal use.

[0092] “Direct contact”: contact between a person and live parts. See IEC 61140.

[0093] "Indirect contact": contact between a person and an exposed, conductive and live part that has become energized through an insulation fault. See IEC 61140.

[0094] “Alignment”: A process of finding the relative position of a secondary device with respect to a primary device and / or the relative position of a primary device with respect to a secondary device for effective power transmission. In the present disclosure, alignment may relate to alignment in a wireless power transmission system, but may not be limited thereto.

[0095] "Pairing": The process of associating a vehicle (EV) with a single dedicated power supply device (master) arranged so that power transfer can occur. This pairing can include the process of associating the EVPC or VA controller with the SPC or GA controller of the charge point.

[0096] The correlation or associating process may include a process of establishing a relationship between two peer communicating entities.

[0097] “Command and control communications”: Communications used to exchange information between the EVSE and the EV required to initiate, control and terminate the wireless power transfer process.

[0098] “High-Level Communications (HLC)”: Digital communications that can handle all information not covered by command and control communications. The data link for HLC can use power line communications (PLC), but is not limited to this.

[0099] "Low Power Activation (LPE)": Technology that activates a supply device (or master device) for fine positioning and pairing, allowing the EV to detect the supply device, and vice versa.

[0100] "Service Set Identifier (SSID)": A unique identifier, comprising 32 characters, that is appended to the header of data packets sent on a wireless LAN. The SSID identifies the Basic Service Set (BSS) to which the wireless device is attempting to connect. The SSID distinguishes between multiple wireless LANs. Therefore, all access points (APs) and all terminal / station devices that want to use a particular wireless LAN can use the same SSID. Devices that do not use a unique SSID cannot join the BSS. Because the SSID is shown as plain text, the SSID may not provide any security features to the network.

[0101] "Extended Service Set Identifier (ESSID)": The name of the network you want to connect to. ESSID is similar to SSID, but it is a more extended concept.

[0102] "Basic Service Set Identifier (BSSID)": The 48-bit BSSID is used to distinguish a specific BSS. With an infrastructure BSS network, the BSSID can be configured for the medium access control (MAC) of the AP device. For an independent BSS or an Ad-hoc network, any value can be used to generate the BSSID.

[0103] The charging station may include at least one GA and at least one GA controller configured to manage the at least one GA. The GA may include at least one wireless communication device. The charging station may refer to a place or location including at least one GA set in a home, office, public place, road, parking area, etc.

[0104] In this specification, “association” may be used as a term representing a process for establishing wireless communication between an electric vehicle communication controller (EVCC) and a supply equipment communication controller (SECC) controlling a charging infrastructure.

[0105] The electric vehicle charging system may include a conductive charging system using a cable or a contactless wireless power transmission system, but is not limited thereto. The electric vehicle charging system may be defined as a system for charging a battery installed in an electric vehicle using power obtained from a commercial power grid or stored in an energy storage device, and the system may have various forms depending on the type of electric vehicle.

[0106] The SAE TIR J2954 standard, one of the most representative industry standards for wireless charging, establishes industry standard specification guidelines that define acceptable standards for interoperability, electromagnetic compatibility, minimum performance, safety and testing for wireless charging of light-duty electric vehicles and plug-in electric vehicles.

[0107] As an example of a wireless charging system, a wireless charging system (WCS) according to the J2954 standard may include a grid interface, a high frequency power inverter, a power transfer coil, a filter, a rectifier, an optional regulator, and a communication circuit between the vehicle energy charging / storage system and the grid-connected power inverter. The grid interface may be similar to a conventional EVSE connection for single-phase or three-phase AC power.

[0108] Exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. In the drawings, the same components may be represented by the same reference numerals to facilitate overall understanding of the present disclosure, and repeated description of the same components will be omitted for simplicity.

[0109] Figure 1 is a schematic diagram of a wireless power transmission system to which an exemplary embodiment of the present disclosure can be applied.

[0110] like Figure 1 As shown, wireless power transmission may be performed by at least one of an electric vehicle (EV) 10 and a charging station 20 , and may be used to transmit power to the EV 10 without any conductive wires.

[0111] The EV 10 according to the exemplary embodiment of the present disclosure may include a hybrid electric vehicle (HEV) having an electric motor and an internal combustion engine, and may include not only a car but also a motorcycle, a cart, a scooter, and an electric bicycle.

[0112] The EV 10 may be generally defined as a vehicle that supplies power obtained from a rechargeable energy storage device, such as a battery 12 , to an electric motor in an electric drivetrain of the EV 10 .

[0113] The EV 10 may include a power receiving pad 11 having a receiving coil suitable for receiving power for charging the battery 12 by wireless power transmission, and may include a plug socket or inlet suitable for receiving power for charging the battery 12 by conductive charging. Specifically, the EV 10 configured for conductive charging of the battery 12 may be referred to as a plug-in electric vehicle (PEV).

[0114] The charging station 20 may be connected to a power grid 30 or a power mains, and may provide AC power received from the power grid 30 or the power mains to a power transmission pad 21 having a transmission coil through a power link.

[0115] The charging station 20 may communicate with the grid 30 or an infrastructure management system or infrastructure server that manages the grid, and may be configured to perform wireless communication with the EV 10. The wireless communication may be performed via Bluetooth, Zigbee, cellular, wireless local area network (WLAN), or the like.

[0116] The charging station 20 may be located in various locations including, but not limited to, a parking area of ​​a home of an owner of the EV 10 , a parking lot for charging EVs at a gas station, a parking lot at a shopping mall or a workplace, and the like.

[0117] Wireless power transmission to the battery 12 of the EV 10 may be performed as follows. First, the power receiving pad 11 of the EV 10 is arranged in the energy field above the power transmission pad 21. Then, the receiving coil in the power receiving pad 11 and the transmitting coil in the power transmission pad 21 may be coupled to each other and interact with each other. Due to the coupling or interaction, an electromotive force may be induced in the power receiving pad 11, and the battery 12 may be charged by the induced electromotive force.

[0118] The charging station 20 and the power transmission pad 21 as a whole or in part may be referred to as a power supply circuit (SPC) or a ground assembly (GA), the meaning and function of which are defined above.

[0119] Furthermore, the power receiving pad 11 together with all or some other internal components of the EV 10 may be referred to as an EV power circuit (EVPC) or a vehicle assembly (VA), the meaning and function of which are defined above.

[0120] Here, each of the power transmission pad 21 and the power reception pad 11 may be configured as a non-polarization pad or a polarization pad.

[0121] A non-polarized pad may have one pole in the center of the pad and opposite poles around its periphery. In this case, magnetic flux may be formed to leave the pole in the center of the pad and return to the pole in the periphery from the outside of the pad.

[0122] The polarized pad may have two magnetic poles symmetrically arranged at opposite positions on the pad. In this case, a magnetic flux may be formed depending on the orientation of the pad.

[0123] In this specification, the power transmission pad 21 and the power receiving pad 11 may be collectively referred to as a wireless charging pad.

[0124] In an exemplary embodiment of the present disclosure, the Y axis of the Cartesian coordinate system may be set to point to the front or rear of the vehicle, the X axis may be set to point to the right or left of the vehicle, and the Z axis may be set to point to the upward or downward direction. The magnetic core of the coil of the power transmission pad 21 or the power receiving pad 11 may be defined as x=0 and y=0, and the ground surface may be defined as z=0.

[0125] In another exemplary embodiment of the present disclosure, the X-axis may be set to point to the front or rear of the vehicle, and the Y-axis may be set to point to the right or left of the vehicle.

[0126] Figure 2 is a circuit diagram of an equivalent circuit of an electric vehicle wireless charging circuit according to an exemplary embodiment of the present disclosure.

[0127] Figure 2The left part of the circuit shown can be interpreted as a representation of the power supply Vsrc supplied from the grid and all or part of the charging station 20 (including the power transmission pad 21), and Figure 2 The right-hand portion of the circuit shown may be interpreted as a representation of all or a portion of an electric vehicle including a power receiving pad and a battery.

[0128] Figure 2 The left side portion of the circuit shown can provide the output power Psrc corresponding to the power supply Vsrc supplied from the power grid to the primary side power converter. The primary side power converter can perform frequency conversion and AC-DC or DC-AC conversion of the power Psrc to output the converted output power P1 to the transmission coil L1, so that the transmission coil L1 can generate an electromagnetic field at a desired operating frequency.

[0129] The primary side power converter may include an AC-DC converter and a low frequency (LF) converter, the AC-DC converter being configured to convert power Psrc, which is AC power supplied from a power grid, into DC power, and the LF converter being configured to convert DC power into AC power having an operating frequency suitable for wireless charging. For example, the operating frequency for wireless charging may be determined to be within a frequency range of 80-90 kHz, but is not limited thereto.

[0130] The power P1 output by the primary side power converter may be supplied to a circuit including a transmission coil L1, a first capacitor C1, and a first resistor R1. Specifically, the capacitance of the first capacitor C1 may be determined to be a value that establishes an operating frequency suitable for wireless charging together with the transmission coil L1. The first resistor R1 may represent power loss in the transmission coil L1 and the first capacitor C1.

[0131] In addition, the transmission coil L1 can be electromagnetically coupled with the receiving coil L2 through the coupling coefficient m, so that the power P2 is transmitted to the receiving coil L2 or the power P2 is induced in the receiving coil L2. Therefore, the meaning of power transmission in the present disclosure can be used interchangeably with the meaning of power induction.

[0132] The power P2 induced in the receiving coil L2 or transmitted to the receiving coil L2 can be provided to the secondary side power converter. Specifically, the capacitance of the second capacitor C2 can be determined to be a value that establishes an operating frequency suitable for wireless charging together with the receiving coil L2. The second resistor R2 can represent the power loss in the receiving coil L2 and the second capacitor C2.

[0133] The secondary-side power converter may include an AC-DC converter configured to convert the supply power P2 of the operating frequency into DC power having a voltage level suitable for the battery VHV of the EV.

[0134] The electric power PHV converted from the electric power P2 supplied to the secondary-side electric power converter may be used to charge a battery VHV mounted inside the EV.

[0135] Figure 2 The right side portion of the circuit shown may also include a switch for selectively connecting or disconnecting the receiving coil L2 from the battery VHV.

[0136] The resonant frequencies of the transmission coil L1 and the reception coil L2 may be similar or identical to each other, and the reception coil L2 may be located in the electromagnetic field generated by the transmission coil L1 .

[0137] It should be noted that Figure 2 The circuit is used to illustrate the WPT in the EV WPT system used in the exemplary embodiment of the present disclosure, and the present disclosure is not limited to Figure 2 The circuit shown.

[0138] On the other hand, since power loss may increase with the distance between the transmission coil L1 and the reception coil L2 , appropriately setting the relative positions of the transmission coil L1 and the reception coil L2 may be an important factor.

[0139] The transmission coil L1 may be included in Figure 1 The transmission pad 21 shown, and the receiving coil L2 may be included in Figure 1 In the receiving pad 11 shown. In addition, the transmitting coil can be referred to as a primary coil or a ground assembly (GA) coil, and the receiving coil can be referred to as a secondary coil or a vehicle assembly (VA) coil. Therefore, the positional alignment between the transmitting pad and the receiving pad or the positional alignment between the EV and the transmitting pad can also be an important factor.

[0140] exist Figure 1 The positional alignment between the transmitting pad 21 and the receiving pad 11 in the electric vehicle 10 shown can correspond to the above-mentioned term "alignment" and can therefore be defined as the positional alignment between SPC / GA and EVPC / VA and is not limited to the positional alignment between the transmitting pad 21 and the receiving pad 11.

[0141] The transmission pad 21 may be located below the ground, may be located above the ground, or may be located below the ground with its top surface exposed above the ground. Figure 2 and Figure 3 As shown, the x-axis may indicate the front-rear direction of the vehicle, the y-axis may indicate the left-right direction of the vehicle, and the z-axis may indicate the up-down direction of the vehicle.

[0142] In addition, the receiving pad 11 of the EV can be defined by different categories according to the height (defined in the z direction) of the receiving pad 11 measured from the ground. For example, a receiving pad 11 with a height of about 100-150 millimeters (mm) from the ground can be classified as category 1. A receiving pad 11 with a height of about 140-210 mm can be classified as category 2. A receiving pad 11 with a height of about 170-250 mm can be classified as category 3. The receiving pad may support only some of categories 1 to 3. For example, only category 1 can be supported by the receiving pad 11, or category 1 and category 2 can be supported by the receiving pad 11.

[0143] The height of the receiving pad measured from the ground may correspond to the term "vehicle magnetic ground clearance" as defined previously.

[0144] At the same time, the vertical position (i.e., the position in the z direction) of the power transmission pad 21 can be determined to be arranged between the maximum category and the minimum category supported by the power receiving pad 11. For example, in the case where the receiving pad supports only category 1 and category 2, the vertical position of the power transmission pad 21 can be within a range between about 100 mm and 210 mm relative to the power receiving pad 11.

[0145] In addition, the gap between the center of the power transmission pad 21 and the center of the power receiving pad 11 can be determined to be arranged within the limits of the horizontal direction and the vertical direction (defined in the x direction and the y direction). For example, the gap (e.g., Δy) can be determined to be within ±75 mm in the lateral direction (defined in the y direction) and within ±100 mm in the longitudinal direction (defined in the x direction).

[0146] The relative positions of the power transmission pad 21 and the power reception pad 11 may be changed according to experimental results, and it should be noted that the above-mentioned numerical values ​​are provided as examples.

[0147] Although the alignment between the pads has been described above based on the assumption that each of the transmission pad 21 and the receiving pad 11 includes a coil, the alignment between the pads may be more specifically defined by alignment between the transmission coil (or GA coil) and the receiving coil (or VA coil) respectively included in the transmission pad 21 and the receiving pad 11.

[0148] Figure 3 An equivalent circuit of a single-phase to single-phase wireless power transmission (WPT) system according to an exemplary embodiment of the present disclosure is shown.

[0149] The magnetic coupling / inductive coupling or resonance structure formed between the primary coil and the secondary coil according to various embodiments of the present disclosure may be formed by Figure 3 The transformers shown are equivalently represented.

[0150] refer to Figure 3 A single-phase rectifier 210 and a sinusoidal pulse width modulation (SPWM) inverter 220 for applying alternating current to the primary coil may be arranged at one side of the primary coil.

[0151] In addition, a rectifier 110 and a charger 120 for transmitting power from the secondary coil to a load or a battery may be arranged at one side of the secondary coil.

[0152] A wireless power transmission system according to an exemplary embodiment of the present disclosure may include a power transmission circuit. Figure 3 The illustrated power transmission circuit may include, as a technical feature, a structure consisting of a single-phase rectifier 210 and an SPWM inverter 220 on the primary coil side.

[0153] Figure 3 The illustrated power transmission circuit according to the exemplary embodiment of the present disclosure may adopt a proportional integral (PI) control scheme based on measurement of the single-phase rectifier 210 as a technical feature to control the single-phase rectifier 210 and the SPWM inverter 220 to apply AC power to the primary coil.

[0154] The SPWM inverter 220 may receive the output of the single-phase rectifier 210 and generate alternating current to supply the alternating current to the primary coil as an output.

[0155] Meanwhile, the alternating current rectified by the rectifier 110 may be supplied to the battery by the charger 120 to recharge the battery.

[0156] Figure 4 1 is a conceptual cross-sectional view and a front view of a conventional power transmission pad which may be a comparative example of the present disclosure.

[0157] Figure 4 A transmission coil 21D is shown, which may be included in a device (eg, Figure 3 In the transmission pad 21 in the device shown). Figure 4 The transmission pad 21 shown can support a single-phase operation mode. Figure 4 If a receiving coil (not shown) of a shape corresponding to the transmitting coil is provided, the receiving pad 11 can perform wireless power reception in the single-phase operation mode. The configuration of the coil and hardware of the receiving pad 11 required for the single-phase operation mode can be modified by those skilled in the art. Figure 4 It is easily implemented by the transmission pad, and its detailed description is omitted for simplicity.

[0158] refer to Figure 4The power transmission pad 21 may include an outer shell 21A forming an outer structure of the power transmission pad 21, an aluminum shield 21B having a flat plate shape and installed inside the outer shell 21A, a ferrite pad 21C installed on or over the aluminum shield 21B, and a transmission coil 21D installed on or over the ferrite pad 21C. Here, "on or over" refers to an upward direction relative to the ground on which the power transmission pad 21 is installed.

[0159] Here, ferrite used for the ferrite pad 21C is a magnetic material containing iron oxide and may affect wireless power transmission by reducing magnetic resistance and facilitating the flow of magnetic flux.

[0160] Figure 5 An equivalent circuit of a three-phase to three-phase WPT system according to an exemplary embodiment of the present disclosure is shown.

[0161] refer to Figure 5 , each of the primary coil and the secondary coil may be implemented by a three-phase coil, and for each phase, the WPT system may include a single-phase rectifier 210A-210C and an SPWM inverter 220A-220C for applying AC power to the primary coil.

[0162] In addition, the rectifiers 110A- 110C may be disposed at one side of the secondary coil for each phase to transfer power from the secondary coil to a load or a battery through the charger 120 .

[0163] Figure 5 The configurations of the single-phase rectifiers 210A-210C, SPWM inverters 220A-220C, and rectifiers 110A-110C shown can be determined by a person skilled in the art based on Figure 3 The illustrated single-phase rectifier 210 , SPWM inverter 220 , and rectifier 110 are easily implemented, and detailed descriptions thereof are omitted for simplicity.

[0164] Figure 6 is a conceptual diagram illustrating a coil structure for three-phase wireless power transmission according to an exemplary embodiment of the present disclosure.

[0165] Figure 7 It is shown Figure 6 Circuit diagram of the equivalent circuit of the coil structure.

[0166] refer to Figure 6 and Figure 7, the coil structure for three-phase wireless power transmission according to an exemplary embodiment of the present disclosure includes a first phase coil 300 corresponding to a first phase. The first phase coil 300 may include a first coil element 320 corresponding to the first phase and arranged to surround a first space 340, and a second coil element 330 corresponding to the first phase and arranged to surround a second space 350 adjacent to the first space 340.

[0167] The first coil element 320 and the second coil element 330 are connected to the same power source. The first coil element 320 and the second coil element 330 are branched at a branch node 360 ​​, and the first coil element 320 surrounds the first space 340 and the second coil element 330 surrounds the second space 350 .

[0168] The coil structure for three-phase wireless power transmission according to an exemplary embodiment of the present disclosure further includes a second phase coil 300 corresponding to the second phase and a third phase coil 300 corresponding to the third phase. The first phase coil 300, the second phase coil 300, and the third phase coil 300 may share a center point 310 and may be disposed to have an angle difference of 120 degrees from each other to correspond to the three-phase input power.

[0169] The three-phase coil 300 may have Figure 6 and Figure 7 That is, the second phase coil 300 corresponds to the second phase and may include two coil elements 320 and 330 arranged to respectively surround adjacent spaces 340 and 350 different from each other.

[0170] The third phase coil 300 corresponds to a third phase and may include two coil elements 320 and 330 arranged to respectively surround adjacent spaces 340 and 350 different from each other.

[0171] The first coil element 320 and the second coil element 330 in each phase coil 300 may be connected to the same power source through a common port.

[0172] The first coil element 320 and the second coil element 330 in each phase coil 300 may share a common feeder portion between the first space 340 and the second space 350 .

[0173] The first coil element 320 and the second coil element 330 may be symmetrically arranged with respect to the common feeder portion.

[0174] The first magnetic field 345 generated in the first space 340 may be in an opposite direction to the second magnetic field 355 generated in the second space 350 .

[0175] According to an exemplary embodiment of the present disclosure, a three-phase wireless power transmission device that is prepared to wirelessly transmit three-phase power to a receiving pad including a secondary coil includes: a first phase coil 300 corresponding to a first phase, a second phase coil 300 corresponding to a second phase, a third phase coil 300 corresponding to a third phase, and a power supply circuit that supplies power to the first phase coil 300, the second phase coil 300 and the third phase coil 300.

[0176] The three-phase coil 300 and the power supply circuit may correspond to Figure 5 The primary side circuit of the three-phase to three-phase WPT system shown. That is, the rectifiers 210A-210C and the inverters 220A-220C that supply the input AC power to the three primary coils having the structure of the above-mentioned phase coil 300 may be included in the power supply circuit on the primary side. Similarly, the rectifiers 110A-110C connected to the three secondary coils having the structure of the phase coil 300 and the charger 120 that charges the battery by induction power may be included in the power receiving and charging circuit on the secondary side.

[0177] Each of the first phase coil 300, the second phase coil 300, and the third phase coil 300 may include a first coil element 320 corresponding to a phase and arranged to surround a first space 340, and a second coil element 330 corresponding to the phase and arranged to surround a second space 350 adjacent to the first space 340. This configuration of the phase coils may be commonly applied to the primary coil and the secondary coil.

[0178] In each of the first phase coil 300, the second phase coil 300, and the third phase coil 300, the first coil element 320 and the second coil element 330 are connected to the same power source as each other. In addition, the first coil element 320 and the second coil element 330 are branched at the branch node 360 ​​so that the first coil element 320 surrounds the first space 340 and the second coil element 330 surrounds the second space 350. This configuration can also be commonly applied to the primary coil and the secondary coil.

[0179] The first phase coil 300, the second phase coil 300, and the third phase coil 300 may be disposed to share a center point 310 and have an angle difference of 120 degrees from each other. This configuration may also be commonly applied to the primary coil and the secondary coil.

[0180] In each of the first phase coil 300, the second phase coil 300, and the third phase coil 300, the first coil element 320 and the second coil element 330 may be connected to the same power source through a common port. This configuration may also be commonly applied to the primary coil and the secondary coil.

[0181] In each of the first phase coil 300, the second phase coil 300, and the third phase coil 300, the first coil element 320 and the second coil element 330 may share a common feeder portion between the first space 340 and the second space 350 and be arranged symmetrically with respect to the common feeder portion. This configuration may also be commonly applied to the primary coil and the secondary coil.

[0182] In each of the first, second, and third phase coils 300, the first magnetic field 345 generated in the first space 340 may be opposite in direction to the second magnetic field 355 generated in the second space 350. This configuration may also be commonly applied to the primary coil and the secondary coil.

[0183] That is, in an exemplary embodiment where both the primary coil and the secondary coil adopt the coil structure of the present disclosure, the common center point of the primary coil and the common center point of the secondary coil can be arranged to share one central axis, so that power transmission efficiency can be improved.

[0184] According to another embodiment of the present disclosure, the common center point of the phase coil in the primary coil (i.e., the center of the primary coil) and the common center point of the phase coil in the secondary coil (i.e., the center of the secondary coil) do not have to be horizontally aligned with the same XY coordinate. Even if the XY coordinates of the center of the primary coil and the center of the secondary coil are inconsistent with each other, power can be wirelessly transmitted from the primary coil to the secondary coil. However, despite this, it is still desirable that the center of the secondary coil is aligned with the center of the primary coil, because severe misalignment of the center of the primary coil and the center of the secondary coil significantly reduces the efficiency of wireless power transmission.

[0185] In addition, it may be desirable that the difference in XY coordinates between the center of the primary coil and the center of the secondary coil be less than a predetermined reference value to ensure desired efficiency of wireless power transmission.

[0186] According to wireless power transmission, energy is transmitted using RF signals, lasers, sound waves, etc. instead of transmitting electrical energy through wires.

[0187] Inductive wireless power transmission is a wireless power transmission technology for transmitting energy through magnetic induction occurring between coils, and is suitable for transmitting high power to charge a large-capacity battery in an electric vehicle, for example.

[0188] The inductive wireless power transmission system includes a transmission coil (ie, primary coil) and a reception coil (ie, secondary coil), and may incorporate a matching circuit to allow the transmission coil and the reception coil to resonate at the same frequency and improve power transmission efficiency.

[0189] Typically, a single-phase inductive wireless power transfer is implemented using a toroidal coil and can provide an effective charging method in a low-capacity wireless charging system. However, due to the high ripple current at high power levels, the toroidal coil may not be suitable for a large-capacity power transfer system.

[0190] The power levels of magnetic field wireless power transfer (MFWPT) for electric vehicle charging are classified into Category 1 (WPT1) to Category 4 (WPT4) based on the maximum input power on the transmitter side, and the maximum input power may range from 1 to 22 kilowatts (kW).

[0191] For wireless power transmission systems with a maximum input power exceeding 11kW, exceeding the power capacity of the single-phase inductive wireless power transmission scheme, it is necessary to use a coil array coil operating in a multi-channel scheme for a large-capacity power transmission system with a maximum input power exceeding 11kW.

[0192] It is conceivable to implement a high power inductive wireless power transfer system by connecting three single-phase systems, each of which may include multiple toroidal coils, but the integration and control of such a configuration in a single device is a complex task and high ripple current may still remain.

[0193] The present disclosure provides a novel coil structure, which can be applied to a three-phase inductive wireless power transmission system with high input power and low ripple current.

[0194] According to an exemplary embodiment of the present disclosure, the three-phase coil 300 is arranged in a stacked configuration so that when a three-phase input voltage with a phase difference of 120 degrees is applied to the three-phase coil 300, the magnetic fields generated by the three-phase coil 300 do not cancel each other and form a large composite magnetic field to ensure efficient power transmission.

[0195] The three-phase wireless power system including the proposed coil structure according to the exemplary embodiment of the present disclosure can achieve large-capacity power transmission exceeding 11 kW more safely and efficiently.

[0196] Each of a transmission coil (i.e., a primary coil) connected to a transmission circuit and a receiving coil (i.e., a secondary coil) mounted on a vehicle is connected to a compensation network including a matching circuit and has a magnetic resonance structure at a specific frequency to realize wireless power transmission of a resonant inductive coupling scheme for transmitting power with high efficiency.

[0197] The current applied to each phase coil of the three-phase coil according to the present disclosure is divided and proceeds to two spiral coil elements connected in parallel, and is recombined at a single node after passing through the corresponding conductors wound with multiple turns. The current can generate a magnetic field parallel to the plane where the coils are arranged at a point located near a common feeder.

[0198] refer to Figure 7 When the magnetic flux formed by the magnetic field 345 of the first space 340 and the magnetic flux formed by the magnetic field 355 of the second space 350 are combined, a magnetic field parallel to the plane in which the coils are arranged (i.e., the coil plane) is formed in the space above the common feed line of the coil elements, and the magnetic field flows from the first space 340 to the second space 350.

[0199] Each phase coil according to an exemplary embodiment of the present disclosure has a structure in which two coil elements are wound multiple turns from a common feeder and connected in parallel. The current flowing in the conductor shared by the two coil elements is divided at a branch point 360 and flows through the two coil elements.

[0200] Currents flowing through the two coil elements in opposite directions relative to the common feed line can generate magnetic fields in the first space and the second space in a direction perpendicular to the coil plane, but the directions of the magnetic fields generated by the currents in the two coil elements are opposite to each other. At the same time, the magnetic field generated by the currents in the two coil elements in the space above the parallel parts of the coil elements is parallel to the coil plane.

[0201] Since the three-phase coils are arranged in a stacked configuration with a 120-degree difference in space, when a sinusoidal AC current with a 120-degree phase difference is applied to the three-phase coils, the magnetic fields generated by the three-phase coils can be added to form a composite magnetic field that rotates with uniform amplitude over time relative to the center axis of the coils.

[0202] The intensity of the X-axis component of the magnetic field generated by the three-phase coil can be expressed by Equation 1. Here, the phase difference θ 2 and θ 3 is 120 degrees, and H 1 , H 2 and H 3 is the maximum strength of the magnetic field produced by each phase coil.

[0203] [Equation 1]

[0204] H 1x =H 1 sinωt cos 0=H 1 sinωt

[0205] H 2x =H 2 sin(ωt+2π / 3)cosθ2 =H 2 sin(ωt+2π / 3)cos(2π / 3)

[0206] =-(1 / 2)H 2 (-(1 / 2)sinωt+(√3 / 2)cosωt)

[0207] H 3x =H 3 sin(ωt+4π / 3)cos(4π / 3)

[0208] =-(1 / 2)H 2 (-(1 / 2)sinωt-(√3 / 2)cosωt)

[0209] By rearranging Equation 1 under the assumption that the balance between the three phases is maintained, the sum of the X-axis components of the magnetic fields generated by the three-phase coils can be expressed by Equation 2.

[0210] [Equation 2]

[0211] H x =H 1x +H 2x +H 3x (If H 0 =H 1 =H 2 =H 3 )

[0212] =(3 / 2)H 0 sinωt

[0213] Similarly, the intensity of the Y-axis component of the magnetic field generated by the three-phase coil can be expressed by Equation 3.

[0214] [Equation 3]

[0215] H 1y =H 1 sinωt sin 0=0

[0216] H 2y =H 2 sin(ωt+2π / 3)sin(2π / 3)

[0217] =(√3 / 2)H 2 (-(1 / 2)sinωt+(√3 / 2)cosωt)

[0218] H 3y =H 3 sin(ωt+4π / 3)sin(4π / 3)

[0219] =-(√3 / 2)H2 (-(1 / 2)sinωt-(√3 / 2)cosωt)

[0220] By rearranging Equation 3 under the assumption that the balance between the three phases is maintained, the sum of the Y-axis components of the magnetic fields generated by the three-phase coils can be expressed by Equation 4.

[0221] [Equation 4]

[0222] H y =H 1y +H 2y +H 3y

[0223] =(3 / 2)H 0 cosωt(if H 0 =H 1 =H 2 =H 3 )

[0224] Combining Equation 2 and Equation 4, the strength of the composite magnetic field can be expressed by Equation 5.

[0225] [Equation 5]

[0226]

[0227] As can be seen in Equation 5, the composite magnetic field exhibits a pattern where the strength of the field is maintained without changing over time, but the horizontal direction of the peak value rotates around the central axis of the coil.

[0228] The strength of the composite magnetic field is the magnetic field strength H generated by the single-phase coil 0 1.5 times of.

[0229] Exemplary embodiments of the present disclosure can realize a coil structure that improves phase symmetry of current and magnetic field distribution between coil elements within a three-phase coil corresponding to respective phases and forms a stable magnetic field distribution.

[0230] The coil structure according to the exemplary embodiment of the present disclosure allows for favorable performance to be achieved particularly in a high frequency band. If an 8-shaped coil is implemented for each phase coil by combining conventional coils, even if the same currents i(t1, p1) and i(t2, p2) are supplied to the first space and the second space through a common feeder, the power transmission efficiency may be low because the magnetic field may fluctuate with time and phase.

[0231] According to the exemplary embodiment of the present disclosure, phase symmetry may be improved so that the obtained magnetic field has an intensity that remains constant without changing over time and has a peak value that rotates around the central axis of the coil.

[0232] The exemplary embodiments of the present disclosure can realize a wireless power transmission (WPT) device and system having an optimized arrangement of a novel magnetic coil structure and exhibiting improved power transmission efficiency. Optimization of the matching circuit to minimize interference can further improve the power transmission efficiency. In addition, optimization of the coil structure and the magnetic core structure can further improve efficiency.

[0233] exist Figure 6 and Figure 7 In the exemplary embodiment shown, the coils can be implemented by flat wires. Each coil can be formed by winding the flat wire at least once.

[0234] Alternatively, in Figure 6 and Figure 7 The coil or coil element in the exemplary embodiment shown can be realized by a litz wire. Each coil can be formed by winding the litz wire at least once.

[0235] Compared with conventional copper wire, the advantages of the stranded wire are that the current flow does not become unstable as the current increases, the loss is small, so that a stable current flow can be maintained, and the temperature rise of the coil is less. Therefore, the stranded wire is an appropriate material for an electric vehicle wireless power transmission system using an operating frequency of 79 to 90kHz. Generally, the price of the stranded wire is set as a price per meter. There are attempts to use the stranded wire in the electric vehicle wireless power transmission system in consideration of these characteristics of the stranded wire.

[0236] However, the wireless power transmission system of the light-load electric vehicle requires a twisted wire with a large current capacity (eg, at least 50 A or more), which is several dozen times more expensive than ordinary twisted wires and may lead to an increase in the manufacturing cost of the electric vehicle.

[0237] Because electric vehicle wireless charging systems transfer large amounts of power wirelessly, strict thermal management is always important. In addition, managing the heating of foreign objects such as metal is important.

[0238] However, due to the structure of the twisted wire in which the inner strand is surrounded by the outer strand, it may be difficult to quickly discharge the generated heat to the outside of the twisted wire. In addition, as the heat generation continues, the current loss in the twisted wire increases. Therefore, it may be difficult to use the twisted wire for a long time. Therefore, the power transmission system using the twisted wire requires a cooling arrangement, which further increases the cost.

[0239] Even if a cooling arrangement is added to the system, the thermal conductivity of the twisted wires may be too low to quickly dissipate the generated heat to the exterior of the twisted wires, and thus the overall cooling efficiency may still be low.

[0240] Furthermore, there may be some situations where consideration of a support structure maintaining the shape of a coil made of litz wires may compromise the safety of the system.

[0241] Although the strength of the stranded wire is higher than that of conventional copper wire and it is convenient to maintain the shape of the wire, the stranded wire is linear, and a coil made of the stranded wire may require a frame to maintain the shape of the stranded wire and the coil. Such a frame is made of an insulator with a low dielectric constant to reduce the electromagnetic influence on the operation of the coil. Insulators with low dielectric constants are generally susceptible to heat and are therefore insufficient for high-power charging of, for example, 22 kilowatts (KW) that generates a large amount of heat. In addition, because the frame is in contact with the stranded wire, the frame may hinder heat exchange, undergo changes in the shape of the frame during repeated heating and cooling processes, or cause a fire.

[0242] Therefore, the present disclosure provides an alternative example in addition to the example using the twisted wire.The wireless power transmission pad or the power receiving pad according to the embodiment of the present disclosure may be implemented using a flat wire.

[0243] The flat and rectangular wire according to the exemplary embodiment of the present disclosure may be a modification of a commercially available flat wire to suit the purpose of the present disclosure.

[0244] The flat wires available on the market usually have almost right-angled corners. These commercially available flat wires are used to improve the space factor. The wire according to an alternative example of the present disclosure maintains its flat shape with at least partially rounded corners.

[0245] The wire proposed by the present disclosure has the following characteristics: 1) having a flat or planar shape, and 2) having a partially circular and / or partially rectangular side. The wire having such characteristics according to the example of the present disclosure can be a flat wire having a shape optimized to generate an electromagnetic field suitable for wireless power transmission when wound into a coil.

[0246] Flat wire and rectangular wire can be obtained in various sizes, for example, single or multiple (e.g., eight), 1.0-1.9 millimeters (mm) thickness range and 3-20 mm width range. In addition, the rectangular wire can be wound into a coil in the form of a continuous transposed conductor (CTC).

[0247] The advantage of coils made from such wire is that the coils can be used in high voltage applications and the conductor bonding of the insulation to the conductor is good enough to select and use one of a variety of insulation materials such as KRAFT, THERMAL UPGRADEKRAFT, NOMEX, DENNISON, KAPTON, MICA, and CONDUCTOFOL.

[0248] If the insulation problem is solved in this way, the number of turns can be increased compared to the existing litz wire coil, and the increase in the number of turns can make it possible to establish increased magnetic flux and improve power transmission efficiency.

[0249] Furthermore, because it is essentially a single cylindrical metal structure when viewed from the outside, heat can be quickly transferred from the inside to the outside without any discontinuity.

[0250] In addition, the twisted wire has a structure in which the inner strand is surrounded by the outer strand as described above. Therefore, when an internal short circuit or insulation deformation or deterioration occurs, it may be difficult to identify the location of the fault, and partial maintenance of the wire may be impossible and the entire coil must be replaced, which leads to an increase in maintenance costs. However, the coil structure using the flat wire or planar wire proposed in the present disclosure is more durable than the twisted wire, and therefore faults such as short circuits in the wire are less likely to occur. In addition, even if a fault occurs, the location where the fault occurs can be easily identified. Therefore, the fault can be repaired immediately, and even if the coil itself is replaced, the replacement cost is low. Therefore, the coil structure according to the present disclosure requires much fewer resources for maintenance.

[0251] In addition, the use of a flat wire structure has the advantages of high heat transfer efficiency and high arrangement freedom, which can selectively apply various cooling technologies such as dry self-cooling, dry air cooling, dry sealed self-cooling, inflow self-cooling, inflow air cooling, inflow air cooling, oil flow water cooling, oil flow air cooling, and refrigerant cooling. Because various cooling technologies can be selectively applied or applied in combination, the embodiments of the present disclosure can have a very favorable effect in cooling the heat generated during power transmission.

[0252] The flat wire according to the exemplary embodiment of the present disclosure may be implemented using at least one material selected from copper and a copper alloy, but the scope of the present disclosure is not limited thereto and various conductors may also be used for the flat wire.

[0253] At the same time, it may be advantageous to establish an electromagnetic field near the coil to at least partially round the corners of the coil. The curvature of the rounded corners may also be determined in consideration of power transmission efficiency, the shape of the coil, and the like.

[0254] In an example, the coil structure 400 or 500 according to an exemplary embodiment of the present disclosure may be implemented based on the shape and material of a busbar forming a conductor connected to a battery within the electric vehicle 10 by determining the numerical ranges of the aspect ratio of the cross section of the wire and the curvature of the rounded corners.

[0255] Comparing the example using twisted wire with an alternative example, although twisted wire is a technology designed to increase the ratio of surface area (i.e., current path) to cross-sectional area or volume, interference between the twisted wires in the central space of the twisted wire bundle (where the twisted wires are densely packed) reduces power transmission efficiency and increases heat generation.

[0256] Because current flows over the surface of a conductor, the ratio of surface area to cross-sectional area can be understood as corresponding to the ratio of the current path to the total volume.

[0257] By proposing a coil structure using a flat wire, examples of the present disclosure may increase the ratio of a surface area to a cross-sectional area and improve a space factor, thereby increasing power transmission efficiency.

[0258] The rounded corners may aid in the formation of the electromagnetic field, resulting in more favorable electromagnetic properties of the coil.

[0259] Although an exemplary embodiment employing a flat ferrite structure is described above, it will be apparent to those skilled in the art that an embodiment in which a ferrite core is formed at the center of the coil is also within the scope of the present disclosure.

[0260] Figure 8 is a flowchart conceptually illustrating a wireless power transmission method according to an exemplary embodiment of the present disclosure. Figure 8 The wireless power transmission method shown may correspond to Figures 1 to 7 The embodiment shown.

[0261] refer to Figure 8 , the wireless power transmission method according to the exemplary embodiment of the present disclosure is a method of wirelessly transmitting power from a transmission pad 21 including a primary coil to a reception pad 11 including a secondary coil.

[0262] According to an exemplary embodiment of the present disclosure, a wireless power transmission method may include: operation S600, providing a three-phase primary coil, each of the three-phase primary coils includes a first coil element and a second coil element, the first coil element is associated with a corresponding phase and is arranged to surround a first space, and the second coil element is associated with the corresponding phase and is arranged to surround a second space adjacent to the first space; operation S800, positioning the common center point of the secondary phase coil within a predetermined offset range from the common center point of the primary phase coil; and operation S900, supplying a three-phase input voltage to the three-phase primary coil and allowing the three-phase input voltage to be wirelessly transmitted to the three-phase secondary coil. In operation S600 of providing a three-phase primary coil, the first coil element and the second coil element in each of the three-phase primary coils are connected to the same power supply. In addition, the first coil element and the second coil element can be branched at a branch point, and the first coil element can be arranged to surround the first space and the second coil element can be arranged to surround the second space.

[0263] In operation S600 of providing the three-phase primary coil, the first coil element and the second coil element in each of the three-phase primary coils may be connected to the same power source through a common port.

[0264] In operation S600 of providing the three-phase primary coil, the first coil element and the second coil element in each of the three-phase primary coil may share a common feeder portion between the first space and the second space and be symmetrically arranged with respect to the common feeder portion.

[0265] In operation S600 of providing the three-phase primary coils, in each of the three-phase primary coils, a first magnetic field formed in a first space may be opposite in direction to a second magnetic field formed in a second space.

[0266] The wireless power transmission method according to an exemplary embodiment of the present disclosure may further include an operation S700 of providing a three-phase secondary coil. The three-phase secondary coil may have the same structure as the three-phase primary coil. The structure of the primary coil and the secondary coil may correspond to Figure 6 and Figure 7 The coil shown.

[0267] Features applicable to operation S600 may also be applicable to operation S700. Figure 6 and Figure 7 When the coil structures shown are the same, the wireless power transmission system according to the exemplary embodiment of the present disclosure can exhibit optimal efficiency.

[0268] Fig. 9 is a block diagram illustrating a general configuration of hardware included in or associated with a wireless power transmission pad and / or a wireless power reception pad to control a sequence for wireless power transmission.

[0269] For convenience of explanation, hardware controlling a sequence for wireless power transmission may be referred to as a controller 1000 .

[0270] The controller 1000 may be disposed on a side of the electric vehicle 100 , a side of an electric vehicle supply equipment (EVSE), or a side of the power transmission pad 21 .

[0271] The controller 1000 may include at least one processor 1100, a memory 1200 storing at least one instruction for performing the above-mentioned operation by the processor 1100, and a communication interface 1300 connected to a network to perform communication. The controller 1000 for wireless power transmission may also include a storage device 1400 capable of storing at least one instruction for performing the above-mentioned operation or data generated during the execution of the instruction. The controller 1000 for wireless power transmission may also include an input interface 1500 and an output interface 1600 for interacting with a user. The components of the controller 1000 for wireless power transmission may be connected to each other through a system bus 1700 to communicate with each other.

[0272] The controller or computing system 1000 according to an embodiment of the present disclosure may include at least one processor 1100 and a memory 1200 storing program instructions instructing the at least one processor 1100 to perform at least one processing step. At least some operations or processing steps of the method according to an embodiment of the present disclosure may be performed by the at least one processor 1100 loading and executing the program instructions from the memory 1200.

[0273] The processor 1100 may include a central processing unit (CPU) or a graphics processing unit (GPU), or may be implemented by another dedicated processor suitable for executing the method of the present disclosure.

[0274] Each of the memory 1200 and the storage device 1400 may include at least one of a volatile storage medium and a nonvolatile storage medium. For example, the memory 1200 may include at least one of a read-only memory (ROM) and a random access memory (RAM).

[0275] Here, at least one instruction may include at least one of the following: a sequence suitable for identifying at least one of the electric vehicle 10, the electric vehicle supply equipment (EVSE) 20 and the power transmission pad 21, a sequence suitable for associating two or more devices among the electric vehicle 10, the electric vehicle supply equipment (EVSE) 20, and the power transmission pad 21 through wireless communication, a sequence suitable for performing alignment and / or pairing through positioning of the other device, and a sequence suitable for allowing supply of alternating current for power transmission after alignment and / or pairing.

[0276] Furthermore, the controller 1000 may include a communication interface 1300 that performs communication through a wireless communication network.

[0277] In addition, the controller 1000 may further include a storage device 1400 , an input interface 1500 , and an output interface 1600 .

[0278] The components of the controller 1000 may be connected to each other through the system bus 1700 to communicate with each other.

[0279] The controller 1000 according to the exemplary embodiment of the present disclosure can be any data processing device that can communicate through a network, such as a desktop computer, a laptop computer, a notebook PC, a smart phone, a tablet PC, a mobile phone, a smart watch, smart glasses, an e-book reader, a portable multimedia player (PMP), a portable game console, a navigation device, a digital camera, a digital multimedia broadcasting (DMB) player, a digital audio recorder, a digital audio player, a digital video recorder, a digital video player and a personal digital assistant (PDA). The device and method according to the exemplary embodiment of the present disclosure can be implemented by a computer-readable program code or an instruction stored on a computer-readable intangible recording medium. The computer-readable recording medium includes a recording device that stores all types of data that can be read by a computer system. The computer-readable recording medium can be distributed on a computer system connected by a network so that a computer-readable program or code can be stored and executed in a distributed manner.

[0280] Computer readable recording media may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, and flash memory. Program instructions may include not only machine language codes generated by a compiler, but also high-level language codes executable by a computer using an interpreter, etc.

[0281] Some aspects of the disclosure described above in the context of a device may indicate a corresponding description of a method according to the disclosure, and a block or device may correspond to the operation of the method or the feature of the operation. Similarly, some aspects described in the context of the method may be expressed by a block, an item, or the feature of a device corresponding thereto. For example, some or all operations of the method may be performed by (or using) a hardware device such as a microprocessor, a programmable computer, or an electronic circuit. In some exemplary embodiments, one or more of the most important operations of the method may be performed by such a device.

[0282] In some exemplary embodiments, a programmable logic device such as a field programmable gate array can be used to perform some or all of the functions of the methods described herein. In some exemplary embodiments, the field programmable gate array can be operated using a microprocessor to perform one of the methods described herein. Typically, the method is preferably performed by a hardware device.

[0283] The description of the present disclosure may be merely exemplary in nature, and therefore, variations that do not depart from the essence of the present disclosure may be intended to fall within the scope of the present disclosure. Such variations may not be considered to depart from the spirit and scope of the present disclosure. Therefore, it will be understood by those of ordinary skill in the art that various changes in form and detail may be made without departing from the spirit and scope defined by the appended claims.

[0284] Industrial Applicability

[0285] According to exemplary embodiments of the present disclosure, a wireless power transmission (WPT) device and system with high power transmission efficiency may be realized by optimizing the arrangement of a novel coil structure.

Claims

1. A coil structure configured for three-phase wireless power transmission (WPT, wireless power transmission), comprising: The first phase coil, corresponding to the first phase, Wherein, the first phase coil comprises: a first coil element corresponding to the first phase and arranged to surround a first space; and a second coil element corresponding to the first phase and arranged to surround a second space adjacent to the first space, The first coil element and the second coil element are connected to the same power source, the first coil element and the second coil element are branched at a branch point, and the first coil element is arranged to surround the first space and the second coil element is arranged to surround the second space.

2. The coil structure according to claim 1, further comprising: A second phase coil, corresponding to the second phase; as well as The third phase coil, corresponding to the third phase, The first phase coil, the second phase coil and the third phase coil are arranged to share a center point and have an angle difference of 120 degrees from each other.

3. The coil structure according to claim 2, wherein: the second phase coil includes two coil elements corresponding to the second phase and arranged to surround respective spaces adjacent to each other, The third phase coil includes two coil elements corresponding to the third phase, and each of the two coil elements is arranged to surround a corresponding space adjacent to each other.

4. The coil structure according to claim 1, wherein: The first coil element and the second coil element are connected to a same power source through a common port.

5. The coil structure according to claim 1, wherein: The first coil element and the second coil element share a common feeder line portion between the first space and the second space.

6. The coil structure according to claim 5, wherein: The first coil element and the second coil element are arranged symmetrically with respect to the common feeder portion.

7. The coil structure according to claim 1, wherein: A first magnetic field formed in the first space and a second magnetic field formed in the second space are opposite in direction.

8. A three-phase wireless power transmission device, configured to wirelessly transmit three-phase power to a receiving pad including a secondary coil (secondary coil), the three-phase wireless power transmission device comprising: A first phase coil corresponding to the first phase; A second phase coil, corresponding to the second phase; The third phase coil, corresponding to the third phase, and a power supply circuit configured to supply power to the first phase coil, the second phase coil, and the third phase coil, Wherein, each of the first phase coil, the second phase coil and the third phase coil comprises: first coil elements corresponding to the respective phases and arranged to surround the first space; and a second coil element corresponding to the corresponding phase and arranged to surround a second space adjacent to the first space, wherein, in each of the first phase coil, the second phase coil, and the third phase coil, the first coil element and the second coil element are connected to the same power source, Among them, in each of the first phase coil, the second phase coil, and the third phase coil, the first coil element and the second coil element are branched at a branch point and are arranged to surround the first space and the second space, respectively.

9. The three-phase wireless power transmission device according to claim 8, wherein: The first phase coil, the second phase coil, and the third phase coil are arranged to share a center point and have an angle difference of 120 degrees from each other.

10. The three-phase wireless power transmission device according to claim 8, wherein: In each of the first phase coil, the second phase coil, and the third phase coil, the first coil element and the second coil element are connected to the same power source through a common port.

11. The three-phase wireless power transmission device according to claim 8, wherein: In each of the first phase coil, the second phase coil, and the third phase coil, the first coil element and the second coil element share a common feeder portion between the first space and the second space and are arranged symmetrically with respect to the common feeder portion.

12. The three-phase wireless power transmission device according to claim 8, wherein: In each of the first phase coil, the second phase coil, and the third phase coil, a first magnetic field formed in the first space is opposite in direction to a second magnetic field formed in the second space.

13. A method of wirelessly transmitting power from a transmitting pad comprising a three-phase primary coil (primary coil) to a receiving pad comprising a three-phase secondary coil (secondary coil), the method comprising: Providing the three-phase primary coils, each phase primary coil comprises: a first coil element associated with a corresponding phase and arranged to surround a first space; and a second coil element associated with the corresponding phase and arranged to surround a second space adjacent to the first space; positioning a common center point of the three-phase secondary coils within a predetermined offset range from a common center point of the three-phase primary coils; and Three-phase input power is supplied to the three-phase primary coil, and the three-phase input power is allowed to be wirelessly transmitted to the three-phase secondary coil.

14. The method according to claim 13, wherein: When the three-phase primary coil is provided, the first coil element and the second coil element in each phase primary coil of the three-phase primary coil are connected to the same power source, The first coil element and the second coil element are branched at a branch point and are arranged to surround the first space and the second space, respectively.

15. The method according to claim 13, wherein: When the three-phase primary coil is provided, the first coil element and the second coil element in each of the three-phase primary coils are connected to the same power source through a common port.

16. The method according to claim 13, wherein: When the three-phase primary coil is provided, the first coil element and the second coil element in each of the three-phase primary coils share a common feeder portion between the first space and the second space and are arranged symmetrically with respect to the common feeder portion.

17. The method according to claim 13, wherein: When the three-phase primary coil is provided, in each of the three-phase primary coils, a first magnetic field formed in the first space and a second magnetic field formed in the second space are opposite in direction.

Images