Low inductance pad winding using multiple spiral matched windings
By using a parallel-connected multi-spindle charging coil design and a ferrite structure, the problems of high inductance and high voltage requirements in wireless power transmission systems are solved, achieving more efficient power transmission and lower voltage drive requirements, thus reducing system costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WIRELESS ADVANCED VEHICLE ELECTRIFICATION INC
- Filing Date
- 2016-06-28
- Publication Date
- 2026-07-14
Smart Images
Figure CN115173573B_ABST
Abstract
Description
[0001] This application is a divisional application of Chinese patent application No. 201680050311.6, filed on February 28, 2018, entitled "Low Inductance Pad Winding Using Matching Windings of Multiple Helices". The international filing date of the parent application is June 28, 2016, and the international application number is PCT / US2016 / 039889. Technical Field
[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 186,257, filed June 29, 2015, entitled “LOWINDUCTANCE PAD WINDING USING A MATCHED WINDING OF MULTIPLE SPIRALS”, which is incorporated herein by reference for all purposes. Background Technology
[0003] Wireless power delivery offers many advantages over wired power delivery. Many devices and systems use wireless power delivery for charging batteries, transmitting power, etc., without the need for connectors, which can fail over time. Devices may require intermittent power delivery, such as for charging batteries, and wireless charging can help mitigate problems associated with connector failure, breaching waterproof or water-resistant barriers, etc.
[0004] With the development of wireless power transmission systems, power levels have increased. Conventional high-power wireless power transmission systems may require relatively high voltages for charging. To reduce costs and voltage hazards, methods to reduce voltage requirements are needed. Summary of the Invention
[0005] This invention discloses an apparatus for wireless power transmission. The apparatus includes a first charging coil in which a first conductor is arranged in a winding pattern and the first windings are arranged around a central point, and each successive winding of the first charging coil is farther from the central point than the first winding and any previous windings. A second charging coil includes a second conductor wound relative to the first charging coil, wherein each coil of the second charging coil is arranged between each winding of the first charging coil. The first and second charging coils are connected in parallel. A ferrite structure is positioned adjacent to the first and second charging coils. In one embodiment, each charging coil has an internal starting point. The internal starting point is located at the beginning of the first winding of the charging coil, and the first winding is closer to the central point than any additional windings of the charging coil. The internal starting points of each charging coil have the same radius emanating from the central point. In another embodiment, the internal starting points of each charging coil are spaced apart around a starting point circle and are equidistant from the internal starting points of other charging coils, the starting point circle being centered on the central point. In one embodiment, the device includes additional charging coils, each including an additional conductor wound relative to a first charging coil, a second charging coil, and any other additional charging coils. Each winding of the additional coil is arranged between each winding of the first and second charging coils and any other additional charging coils. Each charging coil includes an inner starting point. The inner starting point is located at the beginning of the first winding, which is closer to the center point than any additional winding of the charging coil. In this embodiment, the inner starting points of each charging coil are of the same radius emanating from the center point, and are spaced apart around a starting point circle and equidistant from the inner starting points of other charging coils. The starting point circle is centered at the center point. In one embodiment, each charging coil is wound such that, in a specific radial direction emanating from the center point, each successive winding around the innermost winding is farther from the previous winding and positioned substantially planar relative to a line perpendicular to the center point. In another embodiment, each winding of each charging coil is arranged substantially planar. In yet another embodiment, each charging coil is arranged as an Archimedean spiral. In another embodiment, each charging coil is arranged as an irregular helix, wherein the irregular helix includes winding portions that differ in radius relative to a center point, rather than a variation between the start and end points of the winding, to accommodate the start of the next winding of the charging coil and allow for the winding of one or more additional charging coils. In another embodiment, each charging coil is arranged in a substantially square shape and / or substantially D-shaped. In one embodiment, at least a portion of the surface of the ferrite structure is planar and parallel to at least a portion of the adjacent first and second charging coils.In another embodiment, the side of the ferrite structure adjacent to the first and second charging coils is planar, and the first and second charging coils are planar and parallel to the side of the ferrite structure. In another embodiment, the charging coil of the device has a first portion positioned as planar in a first plane and adjacent to a segment of the ferrite structure, and a second portion positioned as planar in a second plane and adjacent to a planar segment of the ferrite structure. The first and second planes are different planes. In another embodiment, the device includes a second set of charging coils positioned adjacent to a first set of charging coils, wherein a portion of each of the first and second sets of charging coils is positioned adjacent and substantially in the first plane, and portions of the first and second sets of charging coils positioned away from adjacent segments of the first and second sets of charging coils are positioned substantially in the second plane. In one embodiment, the conductor of each charging coil includes a first lead and a second lead. The first and second leads include portions of the conductor of each charging coil extending from the winding of the charging coil. At least a portion of the first and second leads of each charging coil are combined in a pattern to increase inductance beyond that of the winding portion of the charging coil, or to subtract inductance from that of the winding portion of the charging coil. This pattern is selected to adjust the total inductance of the charging coil. In another embodiment, the ends of the first leads are connected and the ends of the second leads are connected, such that the charging coils are connected in parallel. In another embodiment, the ferrite structure includes a plurality of ferrite rods arranged in a radial pattern extending away from a center point. A device for wireless power transmission includes a first charging coil with conductors arranged in a winding pattern and a first winding around a center point, and each successive winding of the first charging coil being farther from the center point than the first winding and any previous windings. The device includes one or more additional charging coils, each charging coil including a conductor wound relative to the first charging coil, wherein each coil of the additional charging coil is arranged between each winding of the first charging coil. The first charging coil and the additional charging coils are connected in parallel. Each charging coil has an internal starting point located at the beginning of a first winding of the charging coil, and the first winding is closer to the center point than any of the additional windings of the charging coil. The internal starting points of each charging coil are positioned with the same radius emanating from the center point. The internal starting points of each charging coil are spaced apart around a starting point circle and are equidistant from the internal starting points of other charging coils, and the starting point circle is centered on the center point. The first charging coil and the one or more additional charging coils are connected in parallel and are substantially planar. The device includes a ferrite structure positioned adjacent to the first charging coil and the one or more additional charging coils.At least one side of the ferrite structure is planar and is positioned adjacent to the first charging coil and the one or more additional charging coils.
[0006] A system for wireless power transfer includes a first charging coil in which a first conductor is arranged in a winding pattern and the first winding is around a central point, and each successive winding of the first charging coil is farther from the central point than the first winding and any previous windings. The system includes one or more additional charging coils, each including a conductor wound relative to the first charging coil, wherein each coil of the additional charging coil is arranged between each winding of the first charging coil. The first charging coil and the additional charging coils are connected in parallel. The system includes a ferrite structure positioned adjacent to the first charging coil and the one or more additional charging coils, wherein the charging coils and the ferrite structure are part of a charging pad. The system includes a resonant converter connected to and providing power to the charging pad, or a secondary circuit receiving power from the charging pad and regulating power for a load. In one embodiment, the charging pad is part of a primary charging pad and connected to the resonant converter, and the system includes a second charging pad. The second charging pad is connected to the secondary circuit. The system includes an energy storage device and / or a motor. The energy storage device and / or the motor receives power from the secondary circuit. Attached Figure Description
[0007] To facilitate understanding of the advantages of the invention, the invention briefly described above will be described in more detail with reference to specific embodiments shown in the accompanying drawings. It should be understood that these drawings illustrate only typical embodiments of the invention and should not be construed as limiting its scope. The invention will be described and explained in more detail using the drawings, wherein:
[0008] Figure 1 A block diagram of an exemplary inductive power transfer (“IPT”) charging system is shown;
[0009] Figure 2A This is a schematic block diagram illustrating one embodiment of a device for wireless power transmission having two charging coils and a ferrite structure;
[0010] Figure 2B This is a schematic block diagram illustrating one embodiment of a device for wireless power transmission with two charging coils and an alternative ferrite structure design;
[0011] Figure 3 This is a schematic block diagram illustrating one embodiment of a device for wireless power transmission having two charging coils arranged in a square pattern;
[0012] Figure 4 This is a schematic block diagram illustrating one embodiment of a device for wireless power transfer having four charging coils;
[0013] Figure 5 This is a schematic block diagram illustrating one embodiment of a circuit for analog wireless power transfer, having two charging coils and a receiver coil;
[0014] Figure 6A This is a depiction of the percentage current compared to an error-free simulation for a 1.25% leakage inductance, with the quality factor altered.
[0015] Figure 6B This is a depiction of the simulated phase angle for 1.25% leakage inductance, with the quality factor altered;
[0016] Figure 7A This is a depiction of the percentage current compared to the error-free simulation results for 10% leakage inductance, with the quality factor altered.
[0017] Figure 7B This is a depiction of the phase angle simulation results for 10% leakage inductance, with the quality factor altered;
[0018] Figure 8A This is a schematic block diagram illustrating one embodiment of a device for wireless power transmission having two charging coils and a ferrite structure, as well as a first conductor and a second conductor of the charging coils.
[0019] Figure 8B yes Figure 8A The cross-section of the power supply lead with the first polarity of the first conductor and the second conductor of the device;
[0020] Figure 8C yes Figure 8A The cross-section of the power supply lead with the second polarity of the first and second conductors of the device;
[0021] Figure 9A This is a top view of a schematic block diagram illustrating one embodiment of a device for wireless power transmission having two sets of charging coils arranged in a double-D pattern;
[0022] Figure 9B This is a side view of a schematic block diagram illustrating one embodiment of a device for wireless power transmission having two sets of charging coils arranged in a double-D pattern and a ferrite structure located below the charging coils.
[0023] Figure 9C This is a side view of a schematic block diagram illustrating one embodiment of a device for wireless power transmission having two sets of charging coils arranged in a double-D pattern, with a portion of the charging coils located above the ferrite structure and a portion of the charging coils located below the ferrite structure; and
[0024] Figure 9DIt is a side view of a schematic block diagram of an embodiment of a device for wireless power transmission having two sets of charging coils arranged in a double-D pattern, with a portion of the charging coils located above the ferrite structure and a portion of the charging coils located below the ferrite structure and the split ferrite structure. Detailed Implementation
[0025] Throughout this specification, the terms "an embodiment," "implementation," or similar phrases mean that a specific feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Therefore, throughout this specification, the phrases "in an embodiment," "in an embodiment," and similar phrases may (but not necessarily) all refer to the same embodiment, but rather to "one or more (but not all) embodiments," unless otherwise expressly indicated. The terms "comprising," "including," "having," and variations thereof mean "including, but not limited to," unless otherwise expressly indicated. A list of enumerated items does not imply that any or all items are mutually exclusive and / or mutually inclusive, unless otherwise expressly indicated. The terms "an," "a," and "the" also mean "one or more," unless otherwise expressly indicated.
[0026] Furthermore, the features, structures, or characteristics described in this invention may be combined in any suitable manner in one or more embodiments. Numerous specific details, such as programming examples, software modules, user selection, network transaction processing, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., are provided in the following description to facilitate a thorough understanding of embodiments of the invention. However, those skilled in the art should recognize that the invention may be practiced without one or more specific details, or with other methods, elements, materials, etc. In other instances, well-known structures, materials, or operations have not been shown or described in detail to avoid obscuring aspects of the invention.
[0027] The illustrative flowcharts included herein are generally presented as logical flowcharts. Similarly, the described sequence and identified steps represent one implementation of the provided method. Other steps and methods that are functionally, logically, or operationally equivalent to one or more steps or portions thereof of the method may be contemplated. Furthermore, the format and symbols used are for interpreting the logical steps of the method and should not be construed as limiting the scope of the method. While various arrow and line types may be used in flowcharts, they should not be construed as limiting the scope of the corresponding method. In practice, arrows or other connectors may be used to represent the logical flow of a method. For example, arrows may be used to indicate a wait or monitoring period of unspecified duration between the steps listed in the method. Additionally, the order in which a specific method is performed may or may not strictly follow the order of the corresponding steps shown.
[0028] Figure 1 A block diagram of an exemplary inductive power transfer (“IPT”) charging system 100 is shown. Figure 1 The IPT charging system 100 is one embodiment of a system 100 that may include an IPT system 102, as described below. In other embodiments, the IPT system 102 may be used for purposes other than charging. The IPT system 102 includes a first stage 104, a second stage 106, and wireless power transfer between the first stage 104 and the second stage 106 via an air gap 108. The system 100 includes a load 110 and a voltage source 112. The components of the system 100 are described below.
[0029] The IPT charging system 100 described herein may include a power factor stage 114 powered by a voltage source 112 (such as from a public power grid), such as a primary AC-to-DC power factor stage. In some embodiments, the primary AC-DC converter stage may be configured to convert the grid voltage to a DC voltage 116 (such as a DC bus voltage) for use in a primary tuned resonant converter. A DC output voltage with low output ripple is preferred for high-ripple systems to prevent amplitude modulation signals in wireless inductive power transfer systems, which can lead to reduced efficiency and additional complexity.
[0030] In some implementations, active power factor correction (“PFC”) in the AC-DC converter helps ensure that grid voltage and current are close in phase. PFC reduces total grid current demand and typically reduces grid harmonics. Grid power companies often have specific harmonic requirements for attached industrial equipment. Grid power companies also typically charge extra for supplying power to industrial equipment exhibiting low power factors. In the IPT charging system 100 described herein, one or more suitable stages can be used for PFC. For example, one or more commercial off-the-shelf (“COTS”) AC-DC high-efficiency power factor correction converters can be used. The grid voltage source 112 can be a wide range of voltage inputs, including, for example, single-phase 240VAC, three-phase 208VAC, or three-phase 480VAC. In another implementation, a 400VDC output can be used for this stage, and 400VDC is typically an effective output for a nominal grid input of a single-phase 240VAC grid input. In the United States, a single-phase 240VAC mains voltage with a 30A circuit (suitable for a 5kW IPT system) is common even in areas where industrial three-phase voltage is not supported, and this single-phase 240VAC mains voltage can be used with IPT system 102. For IPT charging system 100, in one embodiment, the first stage 104 includes an LCL load resonant converter 118 controlled by a primary controller 120, which receives feedback signals from the LCL load resonant converter 118 and can send control signals to it. The primary controller 120 can receive information from an alignment sensor 122 for position detection and can communicate using wireless communication 124. The LCL load resonant converter 118 is coupled to a primary receiver pad 126, which is coupled to a secondary receiver pad 128 via an air gap 108. Secondary receiver pad 128 is connected to a parallel decoupling pickup, shown as a secondary circuit 130 controlled by a secondary decoupling controller 132, which can receive feedback signals and send control signals to the secondary circuit 130. The secondary decoupling controller 132 can also communicate with an alignment sensor 136 for position detection for control purposes and can communicate wirelessly 134. The secondary circuit 130 can be connected to a load 110 such as a battery 138 and can charge the battery 138. The battery 138 can provide power to another load such as a motor controller (not shown). The second stage 106 and the load 110 can be located in a vehicle 140. Other embodiments of the IPT system 102 may include wireless power transfer for other purposes, such as battery charging for consumer electronic devices such as mobile phones, electric shavers, and electric toothbrushes. Those skilled in the art will recognize other uses and other IPT systems for wireless power transfer. Figure 2AThis is a schematic block diagram illustrating one embodiment of a device 200 for wireless power transmission having two charging coils and a ferrite structure. Device 200 includes a first charging coil 202, a second charging coil 204, and a ferrite structure 206, as described below. Device 200 includes a first charging coil 202 with a first conductor arranged in a winding pattern and the first windings surrounding a center point 208, and each successive winding of the first charging coil is farther from the center point 208 than the first winding and any previous windings. Device 200 also includes a second charging coil 204 having a second conductor wound relative to the first charging coil 202, wherein each coil of the second charging coil 204 is arranged between each winding of the first charging coil 202. The first charging coil 202 and the second charging coil 204 are connected in parallel. The parallel connection of the first charging coil 202 and the second charging coil 204 is not shown for clarity. Leads from the charging coils 202 and 204 are typically connected such that the charging coils 202 and 204 are connected in parallel. Although two charging coils 202, 204 are depicted in Figure 2, additional charging coils as described below may be included. Advantageously, by splitting the charging coils into two charging coils 202, 204 and connecting them in parallel, the inductance is reduced compared to a non-split design. Lower inductance requires a lower voltage to drive the charging coils 202, 204, thus requiring less voltage on the primary receiver pad 126 to deliver the same amount of power to the secondary receiver pad 128. The lower voltage, in turn, allows designers to eliminate transformers, user components with lower voltage ratings, etc. Each of the charging coils 202, 204 includes a conductor that is generally insulated. This insulation is generally rated for the expected voltage (including spikes, transients, etc.). This insulation prevents the conductors from contacting each other and with other grounded or ungrounded structures. The insulation may include varnish, thermoplastic, nylon, cross-linked polyethylene, rubber, and other insulating materials known in the art. These conductors may be solid or stranded, and may be flexible or solid. In one embodiment, these conductors are Litz wires to reduce the skin effect. Litz wires may comprise a plurality of strands, each insulated. Those skilled in the art will recognize other wire types, insulation, etc., suitable for wireless charging. Device 200 also includes a ferrite structure 206 positioned adjacent to the first charging coil 202 and the second charging coil 204. In one embodiment, ferrite structure 206 includes a planar surface positioned adjacent to the charging coils 202, 204. Typically, device 200 is part of a charging pad (such as primary receiver pad 126 or secondary receiver pad 128), and ferrite structure 206 is designed to enhance the magnetic field above the charging coils 202, 204 to improve coupling with another receiver pad (e.g., 126, 128). Ferrite structure 206 is depicted as circular with an opening at its center, but those skilled in the art will recognize other designs that can be used for the ferrite structure.As used herein, “ferrite structure” includes any structure of a material that can be magnetized or used in transformers, such as those made of [material name missing]. Figure 1 A loosely coupled transformer is formed by a primary receiver pad 126, a secondary receiver pad 128, and an air gap 108, wherein a magnetic field is induced by the current flowing through the charging coils (e.g., 202, 204). The ferrite may include iron oxide, hematite, magnetite, oxides of other metals, or other ferromagnetic materials. For example, Figure 2B This is a schematic block diagram illustrating one embodiment of a device 201 for wireless power transmission with two charging coils and an alternative ferrite structure design. Figure 2B The ferrite structure 206 depicted in the device 201 includes ferrite rods arranged in a radial spoke design. Figure 2B The ferrite structure design described herein has been successfully used for wireless charging of vehicles. In one embodiment, each charging coil 202,204 has an internal starting point. Figure 2A The diagram shows the internal starting point 210 of the first charging coil 202 and the internal starting point 212 of the second charging coil 204. The internal starting point (e.g., 210) of the charging coil (e.g., 202) is located at the beginning of the first winding of the charging coil 202. The first winding is closer to the center point 208 than any additional winding of the charging coil 202. The internal starting points of each charging coil have the same radius emanating from the center point 208 to give the charging coils 202 and 204 symmetry. For example, the internal starting point 210 of the first charging coil 202 may have a radius 214 emanating from the center point 208, and the internal starting point 212 of the second charging coil 204 may also have the same radius 214 emanating from the center point 208. By positioning the internal starting points 210 and 212 at the same radius 214 emanating from the center point 208, the charging coils 202 and 204 can be constructed symmetrical about the center point 208, which can help form charging coils with similar or identical inductance. In another embodiment, the internal starting points of each charging coil are spaced apart around a starting point circle 216 and are equidistant from the internal starting points of other charging coils. The starting point circle 216 is centered at a center point 208 and, in one embodiment, has a radius 214 with the same radius 214 as the internal starting points 210, 212 of the charging coils 202, 204. For example, when using two charging coils (e.g., a first charging coil 202 and a second charging coil 204), the internal starting points 210, 212 are spaced 180 degrees apart around the starting point circle 216. For three charging coils, the internal starting points may be spaced 120 degrees apart; for four charging coils, the internal starting points may be spaced 90 degrees apart, and so on.
[0031] In one embodiment, each charging coil 202, 204 is wound such that, in a specific radial direction 218 emanating from the center point 208, each successive winding around the innermost winding is further away from the previous winding and is positioned substantially planar relative to a line perpendicular to the center point 208, thus the plane is perpendicular to that line. For example, the charging coil may be as follows: Figure 2A , Figure 2B , Figure 3 and Figure 4 In one embodiment, the charging coils 202, 204, etc., are arranged adjacent to each other in the same plane, such that each winding of each charging coil 202, 204 is arranged substantially planar. In another embodiment, at least some windings are positioned in different planes. For example, some windings may be stacked on top of the windings and adjacent to the ferrite structure 206. When the windings are in different planes, in one embodiment, the charging coils 202, 204 each have the same windings in different planes to maintain symmetry. In one embodiment, each charging coil 202, 204 is arranged as an Archimedean spiral. An Archimedean spiral (also called an arithmetic spiral) is formed by the trajectory of points corresponding to positions of points that move away from the center point 208 at a constant speed along a line rotating at a constant angular velocity over time. In another embodiment, each charging coil 202, 204 is arranged as an irregular spiral. Irregular spirals may include winding portions that differ in radius relative to center point 208, rather than in variation between the start and end points of the winding, to accommodate the start of the next winding of the charging coil and allow for windings of one or more additional charging coils. Figure 3 This is an example of an irregular spiral. Figure 3 This is a schematic block diagram illustrating one embodiment of a device 300 for wireless power transmission having two charging coils 302, 304 arranged in a square pattern. Other irregular spirals, such as D-shaped patterns, may also be used. Those skilled in the art will recognize other designs that include multiple charging coils connected in parallel. As mentioned above, other designs may include more than two charging coils. Figure 4 This is a schematic block diagram illustrating one embodiment of a device 400 for wireless power transfer having four charging coils 402, 404, 406, 408. Other designs may include three charging coils, five charging coils, or more.
[0032] It should be noted that multi-coil designs can include non-integer numbers of turns because the termination point of the charging coil (e.g., 202) can be anywhere relative to the internal starting point (e.g., 210). If a coil design using one charging coil has 11 turns, then in a coil design with two charging coils (e.g., 202, 204), each charging coil can have 5.5 turns. Furthermore, for a dual-charging-coil design, the self-inductance of each charging coil is approximately four times smaller than that of a design using a single charging coil. The relationship of self-inductance is thus expressed by equation (1) by comparing a single-charging-coil design with a dual-charging-coil design.
[0033]
[0034] However, these two split-spindle charging coils are coupled to each other, and the coupling coefficient is typically very high and close to 1. Therefore, the mutual inductance between these two charging coils (e.g., 202, 204) is almost the same as their self-inductance. Thus, if the two charging coils 202, 204 are excited using the same phase current, the equivalent self-inductance is:
[0035]
[0036] If the two coils are connected in parallel (Leq||Leq), the resulting inductance is approximately four times the initial value. For N split coils, the new pad inductance is reduced by N². When using this unique method of split Archimedean spirals, the self-inductance of the charging coils is almost identical. This is advantageous because if mismatch exists (e.g., ...), Figure 5 If the mismatch occurs between L1 and L2, and a reflected load exists from the secondary pad to the primary pad, this mismatch can cause current out of phase in the charging coil. Consequently, actual power transfer can occur between these two split coils, which is non-ideal because the current or power generated between the split charging coils is unhelpful. Figure 5This is a schematic block diagram illustrating one embodiment of a circuit 500 for simulating wireless power transfer, having two charging coils and a receiver coil. Circuit 500 includes mutual inductances L1, L2, and L3. L1 is associated with a first charging coil 202, L2 with a second charging coil, and L3 is part of a secondary receiver pad. The first charging coil 202 includes a leakage inductance L4 as a function of L1, and the second charging coil includes a leakage inductance L5 also as a function of L1. The first and second charging coils each include resistors R2 and R3 representing parasitic coil resistance. The secondary receiver pad includes a load resistor R1 and a capacitor C1, where R1, L3, and C1 form a resonant secondary circuit. One consideration in the split charging coil design is whether there is any imbalance in the coupling between the split primary and secondary charging coils, particularly whether there is misalignment between the charging coils, and whether the centers of the two Archimedean spirals are not perfectly matched due to the splitting technique. Figure 6A It shows Figure 5 A comparative study of the 10% coupling change k between coils L1 and L2. Figure 6A The vertical axis in the graph is a comparison of percentage current mismatch with no error, where no error is represented as zero, and Q2 is plotted along the horizontal axis. Figure 6B Having on the vertical axis Figure 5 The phase angle of the current in circuit 500 is shown, and the change in Q2 is located on the horizontal axis. The horizontal axis, labeled Q2, is the quality factor of the secondary circuit, which corresponds to the amount of power supplied to the load R1. As Q2 increases, more power is transferred to the secondary circuit and the load. Although Q2 is shown as increasing to 10, typically Q2 will be lower and usually less than 5. (See also...) Figure 6A It can be seen that when Figure 5 When Q2 is added to circuit 500, the current percentage mismatch between the two charging coils is higher compared to the initial normalized data. Therefore, the higher the quality factor Q2 in the resonant circuit on the secondary circuit, the worse the current mismatch. Furthermore, increasing both currents iL1 and iL2 is not ideal compared to the normalized values. It should also be noted that... Figure 6B The phase difference between the charging coils shown is also very significant, meaning that the two coils are transferring power to each other. When the phase difference between iL1 and iL2 increases to 90 degrees, more current is transferred between the first and second charging coils. Figure 7A and Figure 6A The same applies, except that the leakage inductance has been changed to 10%. Figure 7B Describing the relationship with Figure 7A In the same simulation Figure 7AThe phase angle of the current in the pad. In practice, the leakage inductance in each pad significantly helps reduce the current mismatch between the charging coils on the primary circuit. If the leakage inductance increases to 10%, the current mismatch between iL1 and iL2 is reduced to a negligible amount, such as... Figure 7A and Figure 7B As shown. In practice, a leakage inductance of approximately 25% can be encountered. Therefore, Figure 6A , Figure 6B , Figure 7A and Figure 7B Simulations demonstrate that controlling the leakage inductance between the control coils helps reduce current imbalance. An alternative method for controlling the leakage inductance of the first charging coil 202 and the second charging coil 204 is proposed. Figure 8A This is a schematic block diagram illustrating one embodiment of a device 800 for wireless power transmission having two charging coils 202, 204 and a ferrite structure 206, as well as first and second conductors for the charging coils 202, 204. The power lead 802, including the first and second conductors of the charging coils 202, 204, typically extends to other components of the first stage 104, such as to other elements of the LCL load resonant converter 118 if the first stage 104 includes an LCL load resonant converter topology. Figure 8B yes Figure 8A The cross-section of the first conductor and the second conductor of the device 800 having a power lead of the first polarity. Figure 8C yes Figure 8A The cross-section of the power supply lead with a second polarity in the first and second conductors of the device 800. Figure 8B and Figure 8C In the diagram, the first conductor of the first charging coil 202 is shown at the top, and the second conductor of the second charging coil 204 is shown at the bottom. The "+" sign indicates the current in one direction, and the "-" sign indicates the current in the opposite direction.
[0037] The inductance of the control power lead 802 can be used to adjust the inductance of the charging coils 202 and 204. Figure 8B The configurations of the first and second conductors, which help eliminate the inductance of the power lead 802, are shown. Figure 8C The diagram illustrates a configuration that increases the inductance of power lead 802. Both configurations can be used depending on the situation. For example, a portion of power lead 802 can be as follows: Figure 8A Combined as shown, and some parts can be as follows Figure 8B The combination is shown below. In any design, introducing additional inductance is generally undesirable because it reduces the overall coupling between the equivalent primary and secondary pads; however, introducing some leakage inductance is beneficial, as can be seen in reference... Figure 5 , Figure 6A , Figure 6B , Figure 7Aand Figure 7B As can be seen from the above, a compromise can be used during the actual design phase. Test equipment (not shown) such as... Figure 2B The device 201 depicted is constructed in such a way that the ferrite structure of the test device is designed to be similar to... Figure 2B The ferrite structure 206 of the device 201 is similar, but has a larger structure than that of the device 201. Figure 2B More ferrite rods are depicted. The secondary receiver pad (e.g., 128) is configured with a single coil connected to a secondary circuit (e.g., 130) and a load (e.g., 110). Measurements are taken at various locations for the secondary receiver pad 128. Open-circuit and short-circuit inductances are measured using an LCR meter at 23.4 kHz and Ls-Rs settings. In the test results, the first charging coil 202 is designated as "A", the second charging coil 204 as "B", and the secondary receiver pad 128 as "S". The inductance of the first charging coil 202 is measured when the second charging coil 204 and the secondary receiver pad 128 are open-circuited, thereby determining the self-inductance LA. The inductance of the second charging coil 204 is measured when the first charging coil 202 and the secondary receiver pad 128 are open-circuited, thereby determining the self-inductance LB. When the second charging coil 204 is short-circuited and the secondary receiver pad 128 is absent, the mutual inductance LAB is measured on the first charging coil 202. When the secondary receiver pad 128 is short-circuited and the second charging coil 204 is open-circuited, the mutual inductance LAS is measured on the first charging coil 202. When the secondary receiver pad 128 is short-circuited and the first charging coil 202 is open-circuited, the mutual inductance LBS is measured on the second charging coil 204. When the first charging coil 202 and the second charging coil 204 are short-circuited, the mutual inductance LS1 is measured on the secondary receiver pad 128. When the first charging coil 202 and the second charging coil 204 are open-circuited, the self-inductance LS2 is measured on the secondary receiver pad LS2. The results are shown in Table 1. “Z” is the height of the air gap 108, and “X” and “Y” are the horizontal variations of the secondary receiver pad 128 relative to the fixed primary receiver pad 126 with the first charging coil 202 and the second charging coil 204. The coupling coefficient is then calculated from the measured self-inductance and mutual inductance. “kAS” is the coupling coefficient between the first charging coil 202 and the secondary receiver pad 128, and “kBS” is the coupling coefficient between the second charging coil 204 and the secondary receiver pad 128. “k2” is the coupling coefficient between the secondary receiver pad 128 and the combined inductance of the first charging coil 202 and the second charging coil 204.
[0038] According to Table 1,
[0039] X Y Z kAS kBS k2 0 0 6.21 0.315 0.318 0.340 0 6 6.21 0.251 0.246 0.267 6 0 6.21 0.255 0.254 0.266 4.25 4.25 6.21 0.260 0.256 0.276 0 0 8.21 0.239 0.233 0.256 0 4 8.21 0.231 0.219 0.231 4 0 8.21 0.221 0.227 0.234 2.75 2.75 8.21 0.224 0.207 0.240 0 0 7.21 0.278 0.273 0.294 0 5 7.21 0.239 0.240 0.258 5 0 7.21 0.233 0.237 0.252 2.75 2.75 7.21 0.241 0.237 0.259
[0040] Table 1
[0041] The mismatch in coupling between the primary receiver pad 126, which has a first charging coil, and the secondary receiver pad 128, is well less than 10%. In practice, among all mismatch conditions in the X / Y plane, coupling of approximately 5% has been found at maximum mismatch. In practice, coupling of approximately 0.75% has also been found between the two primary charging coils 202 and 204, meaning that leakage inductance in a real system is more likely to be approximately 25%. Even when... Figure 8C The same applies when the inductance elimination scheme in the 802 is used for a 30-foot power lead.
[0042] When the test system is powered on under worst-case misalignment conditions at full power and maximum output power on the secondary circuit, the observed primary current mismatch is less than 5%. This is negligible for a real-world pad system. Thus, by using this technique, the drive voltage of the resonant stage is halved and the expensive transformer is eliminated without significantly negatively impacting the overall system.
[0043] Another advantage of using split charging coils with parallel connections is that each primary split charging coil can be powered by a modular H-bridge or other converter stage and can be stacked. This will require synchronizing the converter stages, but the system will have high operational availability with N+1 redundancy, meaning that if one converter stage in the N stages fails (e.g., as an H-bridge converter stage), the system can continue to operate using the N-1 stages, or, for both N+1 and N stage operation, if one stage fails, the backup stage can automatically take over. The split charging coil design can also be used for other charging coil configurations. Figure 9A This is a top view of a schematic block diagram illustrating one embodiment of a device 900 for wireless power transmission having two sets of charging coils 904 arranged in a double-D pattern. It should be noted that, although... Figure 9A The device 900 is arranged as a double D, but other patterns, such as... Figure 3 The two square patterns depicted in the text, such as Figure 2A and Figure 2B The two circular patterns depicted in the image, etc. The device 900 includes a ferrite structure 206 customized based on how the charging coil 904 is arranged. For example, the charging coil 904 can be as follows: Figure 9B As shown, this figure is a side view of a schematic block diagram illustrating an embodiment of a device 901 for wireless power transmission having two sets of charging coils 904 arranged in a double-D pattern and a ferrite structure 206 located below the charging coils 904. In this embodiment, the surface of the ferrite structure 206 is planar and forms a first plane 906 parallel to the adjacent charging coils 904. In this embodiment, Figure 9A It can be a top view of device 900, and Figure 9BThis can be a side view of device 901, which is identical to device 900. In this embodiment, the ferrite structure 206 can be a solid ferrite member, or it can have an alternative design. Figure 9C This is a side view of a schematic block diagram of an embodiment of a device 902 for wireless power transmission having two sets of charging coils 904 arranged in a double-D pattern, with portions 908 of the charging coils 904 located above the ferrite structure 206 and portions 910 of the charging coils 904 located below the ferrite structure 206. In this embodiment, Figure 9A It can be a top view of device 900, and Figure 9C This may be a side view of device 902, which is identical to device 900. In this embodiment, the ferrite structure 206 may be a solid ferrite member or may have an alternative design. The ferrite structure 206 is depicted as thicker only to show how the charging coil 904 may be arranged and wound from the top to the bottom of the ferrite structure 206. In this embodiment, the charging coil 904 of device 900, 902 includes a first portion 908 positioned planar in a first plane 906 and adjacent to a segment of the ferrite structure 206, and the charging coil 904 includes a second portion 910 positioned planar in a second plane 912 and adjacent to a planar segment of the ferrite structure 206, wherein the first plane 906 and the second plane 912 are different planes. The ferrite structure 206 may include an opening for the charging coil 904 to access the second plane 912.
[0044] Figure 9D This is a side view of a schematic block diagram of an embodiment of a device 903 for wireless power transmission having two sets of charging coils 904 arranged in a double-D pattern, with portions 908 of the charging coils 904 located above the ferrite structure 914 and portions 910 of the charging coils 904 located below the ferrite structure 914 and the split ferrite structure 914. In this embodiment, Figure 9A It can be a top view of device 900, and Figure 9D This can be a side view of device 903; devices 900 and 903 are identical. In this embodiment, the ferrite structure 206 can be split, such as... Figure 9D As depicted in the diagram. In this embodiment, the charging coil 904 of the devices 900, 902 includes a first portion 908 positioned as planar in a first plane 906 and adjacent to a segment of the ferrite structure 206, and the charging coil 904 includes a second portion 910 positioned as planar in a second plane 912 and adjacent to a planar segment of the ferrite structure 206, wherein the first plane 906 and the second plane 912 are different planes.
[0045] In addition Figure 9A , Figure 9C and Figure 9A , Figure 9D In one embodiment, the second set of charging coils is positioned adjacent to the first set of charging coils, wherein a portion of each of the first set of charging coils and the second set of charging coils 904 is positioned adjacent to each other and positioned substantially in the first plane 906, and portions of the first set of charging coils and the second set of charging coils 904 are positioned away from adjacent sections of the first set of charging coils and the second set of charging coils 904 and are positioned substantially in the second plane 912.
[0046] Figure 9A The implementation plan is advantageous because it is similar to... Figure 2A or Figure 2B Compared to the design shown, positioning the two sets of charging coils 904 adjacent to each other increases the magnetic field height above the charging coils 904. The portions 908 of the two sets of charging coils 904 at the center of the ferrite structures 206, 914 cause an enhanced magnetic field above the charging coils 904. The portions 910 of the charging coils 904 farther from the center of the ferrite structures 206, 914 are less desirable; therefore, placing portions 910 below the ferrite structures 206, 914 and away from the central portions 908 helps prevent these portions 910 from magnetically interfering with the magnetic field above the central portions 908 of the charging coils 904. However, compared to... Figure 9B Compared to the design described in the book, Figure 9C The design increases the thickness of the charging pad device 902. Figure 9D The split ferrite structure 914 of the device 903 can be thinner than Figure 9C Device 902, this is required. Although Figure 9A An opening in the ferrite structure 206 for the charging coil 904 is depicted, but other ferrite structure designs can be used. For example, the charging coil 904 may be wound around the edge of the ferrite structure 206, 914, or the ferrite structure 206, 914 may be constructed from ferrite rods. Other ferrite structure designs will be recognized by those skilled in the art.
[0047] The invention may be embodied in other specific ways without departing from its spirit or essential characteristics. In all respects, the described embodiments should be considered illustrative rather than restrictive. Therefore, the scope of the invention is defined by the appended claims rather than by the foregoing description. All variations falling within the meaning and scope of the equivalents of the claims are included within their scope.
Claims
1. An apparatus comprising: A first charging coil includes a first conductor arranged in a winding pattern having a first winding around a center point, and each successive winding of the first charging coil being farther from the center point than the first winding and any previous winding, the first conductor being in a first plane; A second charging coil includes a second conductor wound relative to a first charging coil, wherein each coil of the second charging coil is arranged between each winding of the first charging coil, the second charging coil lies in the first plane, and the length of the first conductor within the first charging coil matches the length of the second conductor within the second charging coil; and A ferrite structure is positioned in a second plane below the first plane, adjacent to the first charging coil and the second charging coil. The first charging coil and the second charging coil are connected in parallel. The first charging coil and the second charging coil are wound in the same direction, and Each charging coil includes an internal starting point that is closer to the center point of the charging coil than each consecutive winding of the charging coil, and wherein the internal starting points of the first charging coil and the second charging coil are of the same radius emanating from the center point of the charging coil, and the internal starting points of the first charging coil and the internal starting points of the second charging coil are spaced apart in a radial direction around the center point.
2. The apparatus according to claim 1, wherein, Each charging coil is powered by a separate converter stage.
3. The apparatus of claim 1, further comprising an additional charging coil, the additional charging coil comprising an additional conductor wound relative to the first charging coil, the second charging coil, and any other additional charging coil wound around the center point, wherein, Each winding of the additional charging coil, which is wound around the center point, is arranged between the first charging coil and the second charging coil, as well as each winding of any other additional charging coil.
4. The apparatus according to claim 3, wherein, Each charging coil includes an internal starting point, which includes the location where a first winding begins, the first winding being closer to the center point of the charging coil than the other windings of the charging coil. The internal starting points of each charging coil are of the same radius emanating from the center point of the charging coil, and the internal starting points of each charging coil are spaced apart around a starting point circle, equidistant from the internal starting points of other charging coils wound around the center point of the charging coil, the starting point circle being centered on the center point of the charging coil.
5. The apparatus according to claim 1, wherein, Each charging coil is wound such that, in a specific radial direction from the center point, each successive winding around the innermost winding is further away from the previous winding and is positioned as a plane relative to a line perpendicular to the center point.
6. The apparatus according to claim 1, wherein, The spirals of the first charging coil and the second charging coil are Archimedean spirals.
7. The apparatus according to claim 1, wherein, Each charging coil is arranged in an irregular spiral, wherein the irregular spiral includes a winding portion that, apart from the variation between the start and end points of the winding, varies in radius relative to the center point to accommodate the start of the next winding of the charging coil and to allow for the winding of one or more additional charging coils.
8. The apparatus according to claim 1, wherein, The spirals of the first charging coil and the second charging coil are square or D-shaped.
9. The apparatus according to claim 1, wherein, Each charging coil conductor includes a first lead and a second lead, the first lead and the second lead including portions of conductors extending from the winding of the charging coil, wherein at least a portion of the first lead and the second lead of each charging coil are combined together in a certain pattern to achieve one of the following: In addition to the inductance of the charging coil winding, an additional inductance is added; and, Subtract the inductance from the inductance of the charging coil winding. The pattern is selected to adjust the total inductance of the charging coil.
10. The apparatus according to claim 1, wherein, At least a portion of the surface of the ferrite structure is planar and parallel to at least a portion of the first charging coil and the second charging coil.
11. The apparatus according to claim 10, wherein, The side of the ferrite structure adjacent to the first charging coil and the second charging coil is planar, and the first charging coil and the second charging coil are planar and parallel to the side of the ferrite structure.
12. The apparatus according to claim 11, wherein, The charging coil of the device includes a first portion that is positioned as a plane in a first plane and is adjacent to a segment of the ferrite structure, and the charging coil of the device includes a second portion that is positioned as a plane in a second plane different from the first plane and is positioned adjacent to a planar segment of the ferrite structure.
13. The apparatus according to claim 12, wherein, The first charging coil and the second charging coil include a first set of charging coils and a second set of charging coils positioned adjacent to the first set of charging coils. A portion of each of the first set of charging coils and the second set of charging coils is positioned adjacent to the segment of the ferrite structure and positioned in the first plane. A portion of the first set of charging coils positioned away from the adjacent segment of the first set of charging coils and the second set of charging coils is positioned in the second plane. A portion of the second set of charging coils positioned away from the adjacent segment of the first set of charging coils and the second set of charging coils is positioned in the second plane.
14. The apparatus of claim 13, further comprising a first additional portion and a second additional portion of the ferrite structure, wherein both the first additional portion and the second additional portion are located in a third plane, wherein, The first portion of the ferrite structure adjacent to the first group of charging coils and the second group of charging coils in the first plane is magnetically coupled to an additional portion of the ferrite structure, wherein the first additional portion is adjacent to a portion of the first group of charging coils in the second plane, and the second additional portion is adjacent to a portion of the second group of charging coils in the second plane.
15. The apparatus according to claim 1, wherein, The ferrite structure includes a plurality of ferrite rods arranged in a radial pattern extending away from the center point.
16. An apparatus comprising: A first charging coil includes a first conductor, the first conductor including a first terminal and a second terminal, the first conductor having a spiral pattern, the center point of which is located at the center of the first charging coil, wherein the first terminal, the second terminal and the center point of the first conductor are located in a first plane; The second charging coil includes a second conductor, which includes a first terminal and a second terminal. The second conductor has a spiral pattern and its center point is located at the center of the second charging coil. The first terminal, the second terminal, and the center point of the second conductor are located in a first plane. The length of the first conductor in the first charging coil matches the length of the second conductor in the second charging coil. A first ferrite structure is located in a second plane parallel to the first plane, wherein the first charging coil and the second charging coil are adjacent to the first ferrite structure. A second ferrite structure is located in a third plane parallel to the first and second planes, wherein the second ferrite structure is magnetically coupled to the first ferrite structure; and The cable includes a first conductive lead connected to a first terminal of the first conductor, a second conductive lead connected to a second terminal of the first conductor, a third conductive lead connected to a first terminal of the second conductor, and a fourth conductive lead connected to a second terminal of the second conductor. The first conductive lead, the second conductive lead, the third conductive lead, and the fourth conductive lead are arranged in a 2x2 square pattern. Furthermore, the current direction in the first conductive lead, the second conductive lead, the third conductive lead, and the fourth conductive lead is arranged to increase or decrease the inductance of the first charging coil and the second charging coil.
17. An apparatus comprising: A first charging coil includes a first conductor, the first conductor including a first terminal and a second terminal, the first conductor being spiral-shaped, and its center point being located at the center of the first charging coil, wherein the first terminal, the second terminal and the center point of the first conductor are located in a first plane; The second charging coil includes a second conductor, the second conductor including a first terminal and a second terminal, the second conductor being spiral-shaped with its center point located at the center of the second charging coil, wherein each coil of the second conductor is arranged between each winding of the first conductor, wherein the first terminal, the second terminal and the center point of the second conductor are located in the first plane, and wherein the length of the first conductor in the first charging coil matches the length of the second conductor in the second charging coil. A first ferrite structure is located in a second plane parallel to the first plane; A second ferrite structure is located in a third plane parallel to the first and second planes, wherein the second ferrite structure is magnetically coupled to the first ferrite structure; and The cable includes a first conductive lead connected to a first terminal of the first conductor, a second conductive lead connected to a second terminal of the first conductor, a third conductive lead connected to a first terminal of the second conductor, and a fourth conductive lead connected to a second terminal of the second conductor. The first conductive lead, the second conductive lead, the third conductive lead, and the fourth conductive lead are arranged in a 2x2 square pattern. Furthermore, the arrangement of the first conductive lead, the second conductive lead, the third conductive lead, and the fourth conductive lead in a 2x2 square pattern reduces the inductance of the first charging coil and the second charging coil by having adjacent conductive leads carry current in opposite directions.