Patent Application
20170070075
The present disclosure relates generally to wireless power transfer. More specifically, this disclosure relates to devices, systems, and methods of optimizing wireless power transfer to remote systems such as vehicles including batteries in inductive power transfer systems.
Remote systems, such as vehicles, have been introduced that include locomotion power derived from electricity received from an energy storage device such as a battery. For example, hybrid electric vehicles include on-board chargers that use power from vehicle braking and traditional motors to charge the vehicles. Vehicles that are solely electric generally receive the electricity for charging the batteries from other sources. Battery electric vehicles (electric vehicles) are often proposed to be charged through some type of wired alternating current (AC) such as household or commercial AC supply sources. The wired charging connections require cables or other similar connectors that are physically connected to a power supply. Cables and similar connectors may sometimes be inconvenient or cumbersome and have other drawbacks. Wireless Electric Vehicle Charging (WEVC) systems that are capable of transferring power in free space (e.g., via a wireless charging field) to be used to charge electric vehicles may overcome some of the deficiencies of wired charging solutions. As such, wireless charging systems and methods that efficiently and safely transfer power for charging electric vehicles are desirable.
The implementations disclosed herein each have several innovative aspects, no single one of which is solely responsible for the desirable attributes of the invention. Without limiting the scope, as expressed by the claims that follow, the more prominent features will be briefly disclosed here. After considering this discussion, one will understand how the features of the various implementations provide several advantages over current wireless charging systems.
One innovative aspect of the subject matter described in this disclosure can be implemented in a system for reducing magnetic flux of a wireless charging field in a wireless power charging system. The system comprises a wireless power transmitter configured to generate the wireless charging field, the field comprising the magnetic flux and a collector comprising a ferromagnetic material and configured to reduce the magnetic flux. The collector is positioned between a first distance and a second distance at a third distance from the transmitter. The collector is configured to reduce the magnetic flux at a first level at the first distance, at a second level at the second distance, and at a third level at the third distance, the third level greater than each of the first and second levels.
Another innovative aspect of the subject matter described in this disclosure can be implemented in a method of reducing magnetic flux of a wireless charging field in a wireless power charging system. The method comprises generating, via a wireless power transmitter, the wireless charging field, the field comprising the magnetic flux. The method further comprises reducing the magnetic flux via a collector comprising a ferromagnetic material. The collector is positioned between a first distance and a second distance at a third distance from the transmitter, where a magnetic flux reduction of a first level at the first distance and a magnetic flux reduction of a second level at the second distance are less than or equal to a magnetic flux reduction at a third level at the third distance.
Another innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus for reducing magnetic flux of a wireless charging field in a wireless power charging system. The apparatus comprises means for generating the wireless charging field, the field comprising the magnetic flux and means for reducing the magnetic flux, comprising a ferromagnetic material. The reducing means is positioned between a first distance and a second distance at a third distance from the generating means. The reducing means is configured to reduce the magnetic flux at a first level at the first distance, at a second level at the second distance, and at a third level at the third distance, the third level greater than each of the first and second levels.
The above-mentioned aspects, as well as other features, aspects, and advantages of the present technology will now be described in connection with various implementations, with reference to the accompanying drawings. The illustrated implementations, however, are merely examples and are not intended to be limiting. Throughout the drawings, similar symbols typically identify similar components, unless context dictates otherwise. Note that the relative dimensions of the following figures may not be drawn to scale.
The detailed description set forth below in connection with the appended drawings is intended as a description of exemplary implementations and is not intended to represent the only implementations which may be practiced. The term “exemplary” used throughout this description means “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other exemplary implementations. The detailed description includes specific details for the purpose of providing a thorough understanding of the exemplary implementations. In some instances, some devices are shown in block diagram form.
The teachings of this disclosure may be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure. The scope of the disclosure is intended to cover any aspect of the novel systems, apparatuses, and methods disclosed herein, whether implemented independently of or combined with any other aspect of the invention. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the invention is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the invention set forth herein. It should be understood that any aspect disclosed herein may be embodied by one or more elements of a claim.
Although particular aspects are described herein, many variations and permutations of these aspects fall within the scope of the disclosure. Although some benefits and advantages of the preferred aspects are mentioned, the scope of the disclosure is not intended to be limited to particular benefits, uses, or objectives. Rather, aspects of the disclosure are intended to be broadly applicable to different wireless power transfer technologies and system configurations, some of which are illustrated by way of example in the figures and in the following description of the preferred aspects. The detailed description and drawings are merely illustrative of the disclosure rather than limiting, the scope of the disclosure being defined by the appended claims and equivalents thereof.
In the following detailed description, reference is made to the accompanying drawings, which form a part of the present disclosure. The illustrative implementations described in the detailed description, drawings, and claims are not meant to be limiting. Other implementations may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the Figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and form part of this disclosure.
The terminology used herein is for the purpose of describing particular implementations only and is not intended to be limiting of the disclosure. It will be understood that if a specific number of a claim element is intended, such intent will be explicitly recited in the claim, and in the absence of such recitation, no such intent is present. For example, as used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms “comprises,” “comprising,” “includes,” and “including,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.
Wirelessly transferring power may refer to transferring any form of energy via wireless fields, such as electric fields, magnetic fields, electromagnetic fields, wireless charging fields, or otherwise from a transmitter having a “transmitting coil” or “transmitting coupler” to a receiver without the use of physical electrical conductors (e.g., power may be transferred through free space). The power output into a wireless charging field may be received, captured by, or coupled by a “receiving coil” or “receiving coupler” to achieve power transfer.
The electric vehicle 105 is used herein to describe a wireless power receiver. The electric vehicle 105 utilizes, as part of its locomotion capabilities, electrical power derived from a chargeable energy storage device (e.g., one or more rechargeable electrochemical cells or other type of battery). As non-limiting examples, some electric vehicles like the electric vehicle 105 may be hybrid electric vehicles that include, besides electric motors, a traditional combustion engine for direct locomotion or to charge the vehicle's battery. In an implementation, the electric vehicle 105 may draw all locomotion ability from electrical power. Accordingly, the electric vehicle 105 is not limited to an automobile, as shown, and may include motorcycles, carts, scooters, buses, and the like.
As shown, spaces for two electric vehicles 105 are illustrated in a parking area to be parked over corresponding base wireless charging systems 102a and 102b. Each of the base wireless charging systems 102a and 102b also includes a base coupler 104a and 104b, respectively, for wirelessly transferring power. In some other implementations (not shown in
In some exemplary implementations, the EV coupler 116 may receive power when the EV coupler 116 is located in the wireless charging field produced by the base coupler 104a. The wireless charging field corresponds to a region where energy output by the base coupler 104a may be captured by the EV coupler 116. For example, the energy output by the base coupler 104a may be at a level sufficient to charge or power the electric vehicle 105 when received by the EV coupler 116. In some implementations, the level of power transferred may be on the order of one or multiple kilowatts, although the disclosure herein contemplates higher or lower power levels based on the application intended. In some cases, the wireless charging field may correspond to the “near-field” of the base coupler 104a. The near-field may correspond to a region in which there are strong reactive fields resulting from the currents and charges in the base coupler 104a that do not radiate power away from the base coupler 104a (e.g., extending out into the far field). In some cases the near-field may correspond to a region that is within about ½π of the wavelength of the base coupler 104a.
Local distribution center 130 may be configured to communicate with external sources (e.g., a power grid) via a communication backhaul 134, and with the base wireless charging system 102a via a communication link 108. In some aspects communication link 108 may be a wireless or a wired communications link.
In some implementations the EV coupler 116 may be aligned with the base coupler 104a and, therefore, disposed within a near-field region simply by the driver positioning the electric vehicle 105 correctly relative to the base coupler 104a. In other implementations, a sensor circuit or a controller (described with respect to
The base wireless charging system 102a may be located in a variety of locations. As non-limiting examples, some suitable locations include a parking area at a home of the electric vehicle owner, parking areas reserved for electric vehicle wireless charging modeled after petroleum-based filling stations, and parking lots at other locations such as shopping centers and places of employment.
The wireless power charging system 100 as described with reference to
The wireless power transmit and receive capabilities may be configured to be reciprocal such that the base wireless charging system 102a transfers power to the electric vehicle 105 and the electric vehicle 105 transfers power to the base wireless charging system 102a, e.g., in times of energy shortfall. This capability may be useful to stabilize the power distribution grid by allowing electric vehicles 105 to contribute power to the overall distribution system in times of energy shortfall caused by over demand or shortfall in renewable energy production (e.g., wind or solar).
As shown in
The filter and matching circuit 226 may filter out harmonics or other unwanted frequencies and match the impedance of the transmitter 204 to the impedance of the transmit coil 214. As a result of driving the transmit coil 214, the transmit coil 214 may generate a wireless charging field 216 to wirelessly output power at a level sufficient for charging a battery 236 of an electric vehicle, for example.
The transmitter 204 may further include the controller circuit 228 electrically connected to the communication circuit 229 and the transmit circuitry 206. The communication circuit 229 may be configured to communicate with the communication circuit 239 within the receiver 208 over a communications link 219. Communications from the transmitter 204 to the receiver 208 via communications link 219 may comprise information regarding charging processes, including increased or decreased power capabilities of the transmitter 204 and other information associated with the charging capabilities of the transmitter 204 and/or the receiver 208. Unless stated otherwise, each component within the transmit circuitry 206 may have substantially the same functionality as the respective components within any complementary transmit circuitry within the base wireless charging system 102 as previously described in connection with
The receiver 208 may comprise a receive coil 218 and a receive circuitry 210, similar to the EV coupler 116 and electric vehicle charging system 118 of
The receiver 208 may further include a sensor circuit 235 configured to sense a short circuit current or an open circuit voltage of the receive coil 218. A controller circuit 238 may be electrically connected to, and receive sensor data from, the sensor circuit 235. A communication circuit 239 may be connected to the controller circuit 238. The communication circuit 239 may be configured to communicate with the communication circuit 229 within the transmitter 204 over the communications link 219, similar to those noted above. Such communications may serve to indicate to the transmitter 204 specific power demands of the receiver 208, charge state of the battery 236, or other information related to the power requirements of the receiver 208. The communications link 219 may be wireless, for example Bluetooth or Wi-Fi (e.g., out-of-band as compared to the wireless charging field). In some embodiments, the communication link 219 may be in-band (e.g., using modulation of characteristics of the wireless charging field) or a combination of one or more of out-of-band, or in-band communication.
To provide power from the transmitter 204 to the receiver 208, energy may be transmitted from the transmit coil 214 through the wireless charging field 216 to the receive coil 218. In some implementations, the transmit coil 214 and the transmit circuitry 206 form a resonant circuit having a particular resonant frequency. The receive coil 218 and the receive circuitry 210 form another resonant circuit having a particular resonant frequency. Because losses are minimized between two coupled resonant systems having the same resonant frequency, it is desirable for the resonant frequency associated with the receive coil 218 and the receive circuitry 210 to be substantially the same as the resonant frequency associated with the transmit coil 214 and the transmit circuitry 206. The resonant frequency of the resonant circuits may be based on the inductance and capacitance of the resonant circuits. Inductance in the resonant circuit may generally be the inductance created by the transmit coil 214 or the receive coil 218. Capacitance (e.g., a capacitor) may be electrically connected to the transmit coil 214 or the receive coil 218 to create a resonant structure at a desired frequency. For example, a capacitor may be added in series with the transmit coil 214 or the receive coil 218 or may be added in parallel with the transmit coil 214 or the receive coil 218. Thus, it is further desirable that a tuning topology for one or both of the transmit coil 214 and the receive coil 218 is not significantly affected by inductance or load changes. The implementations disclosed herein may incorporate resonant or non-resonant architectures.
In certain implementations, the controller circuit 238 may determine the maximum possible output current or voltage for any position of the receive coil 218 with respect to the transmit coil 214. The controller circuit 238 may make such a determination before supplying current to the battery 236. In another implementation, the controller circuit 238 may make such a determination during charging of the battery 236. Such an implementation may provide a safety mechanism to ensure charging current and/or voltage remain within safe limits during the charging cycle. In yet another implementation the controller circuit 238 may make such a determination while a driver is driving the vehicle 105 (
As noted above, a matched transmit coil 214 and receive coil 218 of the WEVC system 200 may minimize losses. However some loss remains in the form of leakage fields 212a, 212b (collectively “leakage fields” 212). The transfer of energy or power through the wireless charging field 216, or the flux generated by the transmit coil 214 does not typically travel in a straight line to the receive coil 218. Instead, the wireless charging field 216 lines may emanate in some or all directions, away from the transmit coil 214. The wireless charging field 216 lines may be affected by the composition of any surrounding structures (e.g., the ground or the bottom of the electric vehicle 105). Accordingly, not all of the transmitted power actually arrives at the receive coil 218. Some of the transmitted magnetic energy (flux) flows in sub-optimum directions, “leaking” out of the system, becoming “leakage flux,” and thus creating the leakage fields 212. The leakage fields 212 may potentially have negative influence on surrounding electronics or create a safety hazard for people nearby. Accordingly, it may be advantageous to minimize or reduce the leakage field 212 surrounding the transmit coil 214 and the receive coil 218 that flows away from the transmit coil 214.
In an implementation, one or more leakage field collectors 350a and 350b (collectively “collectors” 350) may be positioned to redirect and/or absorb the respective stray leakage fields 212a, 212b. The collectors 350 may be located at a distance 352 from the receive coil 218 or a distance 353 from the transmit coil 214. In some implementations, the collectors 350 may both be located with respect to the transmit coil 214, where both distances 352 and 353 are measured from the transmit coil 214. The collectors 350 may comprise ferrite or other ferromagnetic or ferromagnetic composites such as soft magnetic composites (SMC), nanocrystalline magnetic materials, or plastic bonded ferrite powder among other materials. Certain ferrous materials such as iron oxides, nickel compositions, among others may also be implemented. Composition, placement, and geometry of the collectors 350 may be selected to allow the collectors 350 to redirect and absorb the leakage fields 212. In another implementation, the collectors 350 may be further configured to oppose or negate the leakage fields 212. The ferrite or similar materials of the collectors 350 may be located at a distance from the transmit coil 214 and/or the receive coil 218 such that the collectors 350 provide minimal interference or have minimal or no effect on the transfer of power via the wireless charging field 216. The ferrite or similar materials of the collectors 350 may function differently than any ferrite materials of the transmitter 204 or the receiver 208. For example, ferrite materials of the transmitter 204 or the receiver 208 may direct guide, alter, shape, or enhance the wireless charging field 216 received by the receiver 208, while the ferrite materials of the collectors 350 may collect, redirect, or “absorb” the leakage field 212 to reduce field emissions on the electric vehicle 105 and the surroundings.
The WEVC system 300 may exhibit wireless fields (e.g. the wireless charging field 216, the leakage field 212) of varying strengths and patterns. Accordingly, selection and composition of the collectors 350 may depend on characteristics of a power transmitter and power receiver pair (e.g., the transmit coil 214 and the receive coil 218). In at least one implementation the collector 350 composition, geometry, and position may be based on a position and size of the transmit/receive coil pair. Such a basis may further include the magnitude and location of the leakage field 212 surrounding the electric vehicle 105 (
In another implementation, selection of the collectors 350 may further consider the position of the collectors 350 in relation to the receive coil 218/transmit coil 214 or a height of the receive coil 218 above the ground (not shown in this figure) and/or above the transmit coil 214. In some implementations, the selection of the collectors 350 may further consider a depth of the transmit coil 214 below the ground or a depth of the receive coil 218 within the electric vehicle 105 (not shown in this figure).
In an implementation, the collectors 350 may be formed in one or more of a variety of possible geometries and placements, as discussed below. As shown in
In an implementation, the collectors 350 may comprise low-reluctance ferromagnetic materials having a predetermined geometry and composition selected to most effectively direct, capture, collect, or “absorb” the leakage field 212 to reduce field emissions on the electric vehicle 105 and the surroundings. As used herein, magnetic reluctance may be a scalar, expressed in terms of inverse henry (H−1). In general, air and vacuum have high reluctance while easily magnetized materials such as iron and most ferrous materials may have low reluctance.
Reluctance may be considered to have an inverse relationship with magnetic permeability: R=1/(μ A), where R is the scalar representing reluctance; l is the length of the magnetic circuit in meters; μ is the permeability of the material (dimensionless); and A is the cross sectional area in meters. Thus low reluctance materials are also considered to have “high magnetic permeability.”
As used herein, initial magnetic “permeability” generally refers to a measure of the ability of a material to support the formation of a magnetic field within itself (e.g., the collectors 350). Permeability is typically indicated by the constant, “μ,” or relative magnetic permeability, “μr.” As used herein, relative permeability, generally refers to the ratio of the permeability of a specific medium to the permeability of free space (a vacuum), μ0 (μr=μ/μ0). As a non-limiting example, ferrite may be said to have a relative magnetic permeability of μr=2000; SMC: μr=500; nanocrystalline magnetic material: μr=1000; and plastic bonded ferrite powder: μr=30. As a point of reference, iron (Fe) is commonly held to have a relative permeability of μr=5000. Thus, the higher the permeability of a material, the greater its ability to support the formation of the magnetic field within itself. The foregoing examples are provided as reference, as the magnetic permeability of many ferrous/ferromagnetic/ferrimagnetic materials may vary greatly with magnetic field strength (H). For example, the relative permeability of any material in the presence of a sufficiently high field strength may trend toward one (1).
Considering the foregoing, the magnetic field causes magnetic flux to follow the path of least magnetic reluctance through a material having high relative permeability. Accordingly, the low reluctance characteristics of the collectors 350 may provide a path of least magnetic resistance for the leakage magnetic flux. Thus the collectors 350 may be used to influence the path of the magnetic flux, specifically the leakage fields 212, toward the collectors 350, thereby reducing magnetic field intensity in the vicinity of the receiver 208.
In an implementation, the low reluctance materials of the collectors 350 placed in proximity to the transmit coil 214 may attract magnetic flux, drawing the leakage field 212a in direction 354a and the leakage field 212b in direction 354b toward the collectors 350a and 350b, respectively, as opposed to an outward direction toward external systems and people. Accordingly, the collectors 350 may absorb and influence leakage magnetic flux, and may not oppose or cancel the leakage magnetic fields. In some implementations, the collectors 350 may be configured to absorb and influence leakage magnetic flux or may oppose or cancel the leakage fields 212.
The vehicle shield 406 may comprise electromagnetic shielding materials or components. As a non-limiting example, such shielding materials may include certain metallic meshes or solid metal materials configured to negate any incident magnetic energy or otherwise block or prevent such magnetic energy from entering the passenger compartment of the electric vehicle 405. The vehicle shield 406 may serve to magnetically shield the interior of the electric vehicle 405 from the wireless charging field 416 (similar to the wireless charging field 216 of
The electric vehicle 405 may further comprise the housing 402. As shown, the housing 402 may be disposed or otherwise connected to the bottom of the vehicle shield 406. As shown, the housing 402 is located approximately midway between the front and rear wheels. In an implementation, the housing 402 may be located anywhere on a bottom of the electric vehicle 405 mounted to the vehicle shield 406. In some implementations, it may be useful for the housing 402 to be integrated flush (not shown in this figure) with the lower surface of the electric vehicle 405 and the vehicle shield 406 so that there are no protrusive parts and so that a specified ground-to-vehicle body clearance may be maintained.
In some implementations the housing 402 may contain at least wireless vehicle charging components, such as wireless power receiver (e.g., the receiver 208 of
The electric vehicle 405 is positioned over the transmitter 404. The transmitter 404 is shown emitting the wireless charging field 416. The housing 402 may receive wireless power from the wireless charging field 416 as shown. The wireless charging field 416 is shown in this figure as a series of continuous arrows flowing from the wireless power transmitter 404 to the housing 402. The continuous arrows may be generally representative of the circular or continuous flow of magnetic flux within a magnetic field.
As shown, a portion of the wireless charging field 416 is shown flowing away from the housing 402. While the majority of the continuous arrows comprising the wireless charging field 416 are shown in the vicinity of the housing 402, a portion of the arrows are also flowing horizontally away from the power transmitter 404 to the left and right of
The WEVC system 400 may further comprise one or more leakage field collectors 450a and 450b (collectively known as “collectors” 450). The collectors 450 may be structurally and operably similar to the collectors 350 (
In some implementations, the collector 450 may protrude upward from the ground 475 such that it extends above the surface of the ground 475, wherein the top surface of the collector 450 is elevated above the top surface of the transmitter 404. As noted above, the housing 402 may be integrated into the surface of the ground 475 such that it is flush with the top surface of the ground 475. However, in some implementations, the collector 450 may not protrude from the ground 475 more than the transmitter 404 or may protrude from the ground 475 less than the transmitter 404. Accordingly, in some implementations, the upper portion of the transmitter 404 may protrude from the ground 475 further than the collector 450 (the protrusion not shown in this figure).
In some implementations, the collector 450 may offer a manner to reduce the leakage field 412 (corresponding to the leakage field 212 of
The collectors 450 and the transmitter 404 are shown with distances 453a and 453b (collectively “distance” 453) therebetween. As shown, the collector 450a is spaced the distance 453a from the transmitter 404, while the collector 450b is spaced the distance 453b from the transmitter 404. In some implementations, the collectors 450a and 450b are equally spaced (distances 453a and 453b are the same) from the transmitter 404, though they need not be spaced as such. The collectors 450 may be spaced at distances 453a and 453b from the transmitter 404 that maximize the reduction of the leakage field by the collectors 450. In some implementations, the locations of the collectors 450 and the transmitter 404 may be varied in relation to the vehicle shield 406 (for example, center of the vehicle shield 406, front of the vehicle shield 406, etc.). The locations of the collectors 450 and the transmitter 404 may also be varied based on a type of transmitter coil in the transmitter 404. The variation of the locations of the collectors 450 and the transmitter 404 may impact the distances 453a and 453b.
The WEVC system 500 as shown also includes a distance distx 504, and a distance disty 506. The distx 504 represents the distance between the transmitter 404 and the collector 450 in the x-axis of
As described above in relation to
The graph 600 shows eight (8) curves (lines 602-616) corresponding to different disty 506 (
As depicted, line 606 begins at a reduction of 16%, has a maximum reduction of 28% at 200 mm in the distx 504, and reduces to 24.5% at distx 504 of 350 mm. As depicted, line 608 begins at a reduction of 15%, has a maximum reduction of 26.5% at 200 mm in the distx 504, and reduces to 24.5% at distx 504 of 350 mm. As depicted, line 610 begins at a reduction of 14.5%, has a maximum reduction of 26% at 200 mm in the distx 504, and reduces to 23% at distx 504 of 350 mm. As depicted, line 612 begins at a reduction of 13.5%, has a maximum reduction of 25.5% at 250 mm in the distx 504, and reduces to 23% at distx 504 of 350 mm. As depicted, line 614 begins at a reduction of 12%, has a maximum reduction of 25% at 200 mm in the distx 504, and reduces to 12.5% at distx 504 of 350 mm. As depicted, line 616 begins at a reduction of 11.5%, has a maximum reduction of 24% at 250 mm in the distx 504, and reduces to 22% at distx 504 of 350 mm.
Thus, the graph 600 indicates that for all distances or offsets of the collector 450 and the transmitter 404 along the y-axis, while the distx 504 is increasing, there is a distance along the x-axis at which the reduction of the leakage field 413 by the collector 450 is maximized. After this distance at which the reduction of the leakage field is maximized, the reduction of the leakage field by the collector 450 reduces as the distx 504 continues to increase. Accordingly, there is a distance (along the length of the electric vehicle 405) from the transmitter 404 at which the collector 450 is most effective. Beyond this distance, the collector 450 becomes less effective at reducing the leakage field. Similarly, below this distance, the collector 450 is also less effective at reducing the leakage field. Additionally, this relationship between the distance corresponding to the reduction of the leakage field is shown to apply regardless of the location of the collector 450 in relation to the transmitter 404 along the y-axis. Additionally, or alternatively, a horizontal offset between the housing 402 and the transmitter 404 or variations between the type of transmitter 404 (for example a bipolar transmitter) or the type of receiver within the housing 402 (for example a DD receiver) may also affect the reduction of the leakage field by the collector 450.
For example, for line 602 described above, the maximum percentage of the reduction of the leakage field occurs at or near 200 mm along the x-axis (when the distx 504 between the transmitter 404 and the collector 450 along the length of the car is 200 mm). This maximum reduction of the leakage field (approximately 30%) is a peak reduction of the leakage field that occurs between two reduction values of the leakage field as indicated in
The graph 700 depicts a relationship of reduction of the leakage field by the collector 450 having specified cross sections. For example, when the area of the cross section of the collector 450 is 0.2 cm (representing a surface area of the cross section having dimensions 2 mm×10 mm), the collector 450 reduces the leakage field by approximately 4% as compared to when there is no collector 450. When the area of the cross section of the collector is 2 cm (representing a surface area of the cross section having dimensions 10 mm×20 mm), the collector 450 reduces the leakage field by approximately 43% as compared to when there is no collector 450. As shown in graph 700 and in the data of Table 1 below, the percentage difference in the leakage field of the collector 450 begins to plateau even as the area of the cross section of the collector 450 continues to increase. For example, the increase in the percentage difference in the leakage field of the collector 450 from an increase in the area of the cross section from 0.5 cm (representing a surface area of the cross section having dimensions 5 mm×10 mm) to 1.0 cm (representing a surface area of the cross section having dimensions 10 mm×10 mm) increases from approximately 15% to approximately 30%. However, the increase in the percentage difference in the leakage field of the collector 450 from an increase in relative volume from 2.0 cm (area having dimensions 10 mm×20 mm) to 4.0 cm (area having dimensions 10 mm×40 mm) increases from approximately 43% to approximately 59%. Accordingly, while the area of the cross section of the collector 450 doubles from 0.5 cm to 1.0 cm, the reduction of the leakage field also doubles. However, while the area of the cross section of the collector 450 doubles from 2.0 cm to 4.0 cm, the reduction of the leakage fields increases by only 33%. Thus, the reduction by the area of the cross section of the collector 450 has of the leakage field reduces as the area of the cross section of the collector 450 increases once the area of the cross section passes a specified point, thus defining a point at which a ratio between the reduction of the leakage field and the area of the cross section of the leakage collector becomes negligible.
Thus, the graph 700 indicates that as the area of the cross section of the collector 450 is increased, there is an area of the cross section above which the reduction of the leakage field is saturated. Accordingly, there may be an area of cross section of the collector 450 at which increasing the area of the cross section is not beneficial or cost effective in relation to the reduction of the leakage field.
The graph 750 charts three (3) lengths (lines 702-706) corresponding to a collector length (in millimeters), the collector length being a second dimension of the cross section of the collector 450. Given the collector length (lines 702-706) and the collector width (x-axis), the graph 750 indicates the reduction of the leakage field of various collector widths given the collector lengths of lines 702-704. For example, each line 702-706 indicates a different collector cross section length 2 mm, 5 mm, and 10 mm, respectively. Accordingly, the line 702 indicates that a collector 450 having a cross section length of 2 mm and a collector cross section width of 10 mm will reduce the leakage field by approximately 9% as compared to no collector 450. Table 1 below provides the thickness, width, volume, and cross section area of the collectors 450 along with the reduction of the leakage field data indicated on graphs 700 and 750 of
Electric vehicles 405 (
The collectors 450 may further be placed in a position (in relation to the transmitter 404) that most effectively takes advantage of the selected shape and/or composition of the collectors 450. Different collector 450 shapes may have different effects on leakage field distributions. Accordingly, different shapes of the collectors 450 may have different positions in relation to the transmitter 404. Additionally, or alternatively, a type of coil (e.g., polarized vs. non-polarized) used within the transmitter 404 may have different magnetic field distributions (and, accordingly, different flux distributions), thus utilizing collectors 450 of different shapes, positions, and/or compositions.
In some implementations, the collectors 450 may be disposed a specific distance from the transmitter 404, providing free space between the transmitter 404 and the collectors 450. The collectors 450 may exist above, below, or at the same height as the transmitter 404. Vertical positioning of the collectors 450 in relation to the transmitter 404 and the housing 402 may influence an optimal distance between the transmitter 404 and the collectors 450. In some implementations, the collectors 450 may be positioned as high as possible between the transmitter 404 and the housing 402 to guide the leakage flux to the housing 402 or reduce the leakage flux
The collectors 450 may further be placed at the front, rear, or the sides of the electric vehicle 405 as the electric vehicle 405 is positioned over the transmitter 404 for charging. The orientation of the collectors 450 may further be considered. Certain leakage field 412 flux patterns may react differently to collectors 450 positioned in parallel to the lines of flux versus collectors 450 placed orthogonal to the lines of flux. Additionally, the mounting position of the collectors 450 in relation to the transmitter 404 and the housing 402 may impact the leakage field 412 reduction of the collectors 450. Additionally, dimensions or compositions of the vehicle shield 406 or the electric vehicle 405 or the positioning of the housing 402 may impact the leakage field 412 and thus impact the leakage field reduction by the collectors 450.
The collectors 450 may further be selected in varying quantities. For example, a segmented collector 450 (see the collectors 845a, 845b of
In some implementations, the leakage collectors 450 described herein may reduce leakage fields 412 in dynamic charging systems (systems that transmit power wirelessly while the electric vehicle 405 is moving). For example, the transmitter 404 and the housing 402 may wirelessly transmit power in the WEVC system 400 configured to transmit power wirelessly to moving electric vehicles 405 or in dynamic charging systems where the electric vehicles 405 are not in a single position for an extended period of time (for example, at an intersection). The dynamic charging systems may have leakage collectors 450 positioned to reduce leakage fields 412 in a direction of pedestrians, animal, or plants, etc. (for example, along a sidewalk or a crosswalk). Accordingly, the various shapes, dimensions, and orientations of the collectors 450 described above may provide for selective reduction of the leakage flux 412 in a desired direction or location in the dynamic charging systems.
The electric vehicle 405 may further comprise the housing 402 positioned on the bottom of the vehicle shield 406, as described above in reference to previous implementations (e.g.,
In one implementation, the leakage collectors 902a, 902b may represent cross section views of individual segments of one or more of the collectors described above (e.g., the collectors 810a, 810b, 820a, 820b, 825a, 825b, 845a, 845b etc.). In another implementation, the collectors 902a, 902b may be a cross sectional view of a continuous collector (e.g., the collectors 805, 840, etc.). Accordingly, the collectors 902a, 902b may show the shape of any of the leakage collectors described herein.
The collectors 902a, 902b are disposed on the ground 475. The collectors 902a, 902b may be mounted to, beside, or on the ground 475 according to a given design. In some implementations, the collectors 902a, 902b may be mounted to the transmitter 404 or beside, above, or below a plane in which the transmitter 404 is positioned. The collectors 902a, 902b of
It is to be noted that geometry, position, and layout the planar views of the collectors 805, 810, 815, 820, 825, 830, 835, 840, and 845 may be combined in part or in whole with the various cross sections of collectors 902, 904, 906, 908. Certain implementations may include multiple types and geometries of the collectors disclosed herein. It should further be noted that implementations described above are not drawn to scale, thus any specific dimensions are not limiting.
Additionally, the implementation of various shapes, cross sections, and dimensions of collectors 350 (
Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.
The various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the implementations disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. The described functionality may be implemented in varying ways for each particular application, but such implementation decisions may not be interpreted as causing a departure from the scope of the implementations of the invention.
The various illustrative blocks, modules, and circuits described in connection with the implementations disclosed herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The steps of a method or algorithm and functions described in connection with the implementations disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a tangible, non-transitory computer-readable medium. A software module may reside in Random Access Memory (RAM), flash memory, Read Only Memory (ROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. A storage medium is coupled to the processor such that the processor may read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above may also be included within the scope of computer readable media. The processor and the storage medium may reside in an ASIC.
For purposes of summarizing the disclosure, certain aspects, advantages and novel features of the inventions have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular implementation of the invention. Thus, the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.
Various modifications of the above described implementations will be readily apparent, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the implementations shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
