The present invention is in the field of wireless or inductive power transfer. More particularly, but not exclusively, the present invention is directed to systems and methods for inductive power transfer for consumer electronic devices.
IPT technology is an area of increasing development and IPT systems are now utilised in a range of applications and with various configurations. One such application is the use of IPT systems in so called ‘charging mats’ or pads. Such charging mats will normally provide a planar charging surface onto which portable electronic devices (such as smartphones) may be placed to be charged or powered wirelessly.
Typically, the charging mat will include a transmitter having one or more power transmission coils arranged parallel to the planar charging surface of the charging mat. The transmitter drives the transmitting coils so that the transmitting coils generate a time-varying magnetic field in the immediate vicinity of the planar surface. When portable electronic devices are placed on or near the near the planar surface, the time-varying magnetic field will induce an alternating current in the receiving coil of a suitable receiver associated with the device (for example a receiver incorporated into the device itself). The received power may then be used to charge a battery, or power the device or some other load.
A problem associated with charging mat design is ensuring that the inductive power transfer is adequately efficient for different orientations of receiving coils. That is, for planar or flat devices, such as smartphones, the receiving coil associated with the device will typically be placed in a parallel plane to the transmitting coil(s) by being placed on the interface surface of the charging mat such that coupling is maximised and therefore power transfer is reasonably efficient. However, for non-planar or arbitrarily shaped devices, such as wearable devices, the receiving coil(s) associated with the device may be placed at a arbitrary angle or orientation relative to the transmitting coil(s) of the charging mat because the device itself may not sit flat on the interface surface of the charging mat. This situation may also occur for planar devices if a user wishes to orient the device for ease of use during charging/powering, e.g., the user props the device at an angle to the interface surface so that a screen of the device can be interacted with. Thus, without requiring device designers to provide ‘flat’ exterior surfaces for the coupling with the receiving coils or forcing users to not deviate from a co-planar orientation of their device, the efficiency of wireless power transfer may be significantly deteriorated, thereby limiting the applicable uses of charging mats.
Another problem associated with charging mat design is enabling multiple devices to be charged simultaneously in an efficient and cost effective manner. Some conventional designs use a single large transmitting coil corresponding to the entire surface of the charging mat. In this instance, one or more devices may be placed anywhere on the surface of the charging mat. This allows more freedom in terms of where a user may place a device on the charging mat. However, the magnetic field produced by a large transmitting coil may not be uniform, with ‘weak spots’ towards the centre of the charging mat, and the problems with arbitrary receiving coil orientation are not ameliorated. Further, since the entire surface is being ‘powered’ it is possible that any portions of the surface not covered by a device being charged may be a safety hazard.
Another conventional approach for multi-device charging is to have an array of transmitting coils. In order to provide efficient and safe power transfer, the charging mat detects the position of the devices using a suitable detection mechanism and activates the most proximate transmitting coil or coils. Though this allows more freedom in terms of where a user may place a device, like the single coil design, the boundary between adjacent transmitting coils can result in weak spots due to the cancelling effects of adjacent coils whereby receivers do not receiver sufficient power, and the problems with arbitrary receiving coil orientation are not ameliorated.
The invention provides an inductive power transfer system and methods that achieve reliable and efficient wireless power transfer for arbitrarily placed and orientated device powering or at least provides the public with a useful choice.
According to one exemplary embodiment there is provided a wireless power transfer system comprising:
It is acknowledged that the terms “comprise”, “comprises” and “comprising” may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, these terms are intended to have an inclusive meaning, i.e., they will be taken to mean an inclusion of the listed components which the use directly references, and possibly also of other non-specified components or elements.
Reference to any prior art in this specification does not constitute an admission that such prior art forms part of the common general knowledge.
The accompanying drawings which are incorporated in and constitute part of the specification, illustrate embodiments of the invention and, together with the general description of the invention given above, and the detailed description of embodiments given below, serve to explain the principles of the invention.
An inductive power transfer (IPT) system 1 is shown generally in
A controller 8 is provided to control operation of the inductive power transmitter 2 and may be directly or indirectly connected to several or all parts of the transmitter 2. The controller 8 receives inputs from the various operational components of the inductive power transmitter 2 and produces outputs that control that operation. The controller 8 may be implemented as a single unit or separate units, configured to control various aspects of the inductive power transmitter 2 depending on its capabilities, including for example: power flow, tuning, selectively energising transmitting coil or coils 7, inductive power receiver detection and/or communications. Whilst the transmitter is depicted as a charging mat or device, other configurations are possible in the scope of the present invention, such as a transmitter integrated into the surfaces of non-device objects, such as bench tops or desk tops of furniture, and the interiors of motor vehicles.
The inductive power receiver 3 includes a power pick-up stage 9 connected to power conditioning circuitry 10 that in turn supplies power to a load 11. The load may be an electrically operational part of an electronic device or machine, or may be one or more power storage elements. The power pick-up stage 9 includes an inductive power receiving coil or coils. When the coil(s) of the inductive power transmitter 2 and the inductive power receiver 3 are suitably coupled, the alternating magnetic field generated by the transmitting coil or coils 7 induces an alternating current in the receiving coil or coils. The receiving coil or coils may be connected to capacitors and additional inductors (not shown) either in parallel, series or some other combination, such as inductor-capacitor-inductor, to create a resonant circuit. In some inductive power receivers, the receiver may include a controller 12 which may control tuning of the receiving coil or coils, operation of the power conditioning circuitry 10, characteristics of the load 11 and/or communications.
The term “coil” may include an electrically conductive structure where an electrical current generates a magnetic field. For example inductive “coils” may be electrically conductive wire in three dimensional shapes or two dimensional planar shapes, electrically conductive material fabricated using printed circuit board (PCB) techniques into three dimensional shapes over plural PCB ‘layers’, and other coil-like shapes. Other configurations may be used depending on the application. The use of the term “coil”, in either singular or plural, is not meant to be restrictive in this sense.
Current induced in the power pick-up stage 9 by transmitting coil or coils 7 will typically be high frequency AC at the frequency of operation of the transmitting coil or coils 7, which may be for example, 20 kHz, up to hundreds of megahertz or higher. The power conditioning circuitry 10 is configured to convert the induced current into a form that is appropriate for powering or charging the load 11, and may perform for example power rectification, power regulation, or a combination of both.
In order to ensure maximum power transfer efficiency to the arbitrary receiver device 206 the present invention further provides a power transfer adaptor 208 which functions to reorient the power transferring field of the power transmitter for full receipt by the receiver circuitry of the device 206. In
Example transceiver electronics 500 of the adaptor unit 208 are depicted in block diagram form in
The power received by the power pick-up stage 502 is transferred to the power transmitting stage 504 via the connection stage 506. This power is supplied to one or more transmitting coils of the power transmitting stage 504, and as the power received by the power pick-up stage 502 represents an AC signal, this AC signal is conveyed to the transmitting coil(s) thereby generating an alternating magnetic field so that when the coil(s) of the inductive power receiver 3 and the transmitting coil(s) of the adaptor unit 208 are suitably coupled, the alternating magnetic field generated by the transmitting coil(s) induces an alternating current in the receiving coil(s) of the receiver 3. The transmitting coil(s) may be connected to capacitors and additional inductors (not shown) either in parallel, series or some other combination, such as inductor-capacitor-inductor, to create a resonant circuit. The connection stage 506 may include power conditioning and/or control circuitry for conditioning the power conveyed to transmitting coil(s) of the adaptor unit and/or controlling tuning of the transmitting coil(s), operation of the power conditioning circuitry and/or communications.
In the simplest form, the connection stage 506 is merely a conductive path between the receiving coil(s) and transmitting coil(s), so that minimal power is lost. This is depicted in conceptual form in
The adaptor receiving and transmitting coils depicted in conceptual form herein, are generally comprised of a spirally wound coil of conductive material on a supporting plate of magnetically permeable material, such as a ferrite. However, as described earlier other ‘coil’ configurations are possible. The magnetically permeable material enhances the coupling of the adaptor coils to the external coils of the transmitter and receiver devices. The magnetically permeable material is further positioned within the adaptor unit so that the adaptor receiving and transmitting coils are suitably decoupled from one another, thereby ensuring no interference between the coils. The adaptor coils may be similarly shielded from other electronics within the adaptor unit and or the external environment.
In the example depicted in
Further ease for a user however can be provided by configuring the transceiver electronics of the adaptor unit 208 so that multiple power transmission planes are provided. To this end,
In the multiple transmitting coil embodiments of the adaptor unit, the plural transmitting coils may be simultaneously operated through constant connection to the adaptor receiving coil(s) via the connection stage, or operation may be selective. Selective operation may be provided by suitable switching control in the electronics of the connection stage 506 so that only selected adaptor transmitting coils are connected to the adaptor receiving coil at any time. This selection could be controlled using a suitable controller, such as a digital controller in the form of a programmable integrated circuit, e.g., a microcontroller, or as an analog controller in the form of discrete circuit components.
Selection of the adaptor transmitting coil or coils required to transfer power to a proximate receiver device could be governed by suitable detection of the proximity of the receiver device. This can be achieved, for example, using suitable sensors or detection techniques within the adaptor electronics. As one example, the Applicant has found that receiver devices which generally include ferrite in conjunction with the receiving coils provide reflected impedance characteristics which are different to objects having metal only, e.g., little or no magnetically permeable material. This situation can therefore be used to detect the presence of a receiver object, and power transfer can be established based on this or on further detection techniques, such as analogue or digital communications with applicably capable receiver devices. Indeed, depending of the type of charging mat that the adaptor unit is placed upon, the presence of the adaptor unit itself can be ascertained by the power transmitter using a similar technique, since the adaptor unit has ferrite associated with the base coil 600. Further, in IPT systems in which communications between transmitter and receiver devices is implemented using the IPT field itself, e.g., through amplitude, frequency and/or phase modulation of the IPT field, such communication can be carried out through the transceiver network of the adaptor unit. Further, the transceiver electronics of the adaptor itself can be provided with suitable modulation/demodulation circuitry to allow independent communications with the transmitter and receiver devices, thus allowing establishment of ‘power contracts’ between the adaptor and power transmitter and/or between the adaptor and the power receiver.
In some embodiments one or more coil may be dedicated receive coils and one or more coils may be dedicated transmit coils. In a preferred embodiment each flat face may have an associated coil proximate the face that may be dynamically configured to be a receive or a transmit coil based on monitoring of the coils by a wireless power transfer adaptor of the wireless power transfer system. The wireless power transfer adaptor may monitor the coils and upon detecting a coil receiving power may configure that coil to be a power receiving coil. The wireless power transfer adaptor may then monitor the other coils to determine if there is a device proximate one of the other coils demanding power and configure that coil as a power transmitting coil. The transmitter coil configuration may also be performed based on communication between the wireless power transfer adaptor and a device to be charged.
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In the afore-described example configurations of the wireless power transfer adaptor, the ‘body’ of the adaptor unit is rigid or static, meaning that the possible relative orientations of the interface surface of the transmitter and the receiver device are set. However, in a further example configuration of the adaptor unit, the body may be at least partly formed of a mouldable and conformable material. In this way, the adaptor body can be moulded and remoulded depending on application where the adaptor electronics within is flexible through, for example, a flexible connection stage 506. The mouldable material may be any suitable material that can be moulded to retain the moulded shape thereby providing structure for the desired form for the adaptor unit without interfering with operation of the encased electronics or with the inductive magnetic fields used by the system. Such material may be, for example, gel, polymer, clay or bendable plastic. The adaptor electronics may be embedded within the mouldable material, for example, by pouring or shaping the material about the electronics, or by having the material press- or snap-fitted about the internal components, which are held in place by the mouldable material itself or by adhesive or the like.
Whilst the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in detail, it is not the intention to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of the general inventive concept.
Filing Document | Filing Date | Country | Kind |
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PCT/NZ2016/050035 | 3/4/2016 | WO | 00 |
Number | Date | Country | |
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62180420 | Jun 2015 | US | |
62129214 | Mar 2015 | US |