The present invention relates generally to wireless power transfer systems, such as wireless charging systems, and, more particularly, to techniques for handling high Z-gap configurations for wireless power transfer.
Within the power transmitter 110, the power conversion module 112 converts DC input power Pin 111 having input voltage Vin into an AC signal that is applied to the TX inductor coil 114, which is inductively coupled to the RX inductor coil 122 of the power receiver 120. Within the power receiver 120, the power pick-up module 124 converts the analog signal induced in the RX inductor coil 122 to a DC output power Pout on an output pin 125 having output voltage Vout. In some applications, the power receiver 120 is part of a rechargeable, battery-powered consumer device, such as a cell phone, where the DC output power Pout is used to recharge the device battery.
The TX and RX communication modules 116 and 126 transmit and receive communication messages. For example, the RX communication module 126 transmits upstream messages to the TX communication module 116 to instruct the power conversion module 112 to increase or decrease the power level of the transmitted power based on the needs of the power receiver 120. The TX and RX control modules 118 and 128 control the operations within the power transmitter and receiver 110 and 120, respectively.
Among other factors, the efficiency with which power is wirelessly transmitted from the power transmitter 110 to the power receiver 120 is a function of both the sizes of the TX and RX inductor coils 114 and 122 and the distance (also known as the Z gap) between the two coils 114 and 122. In general, the larger the coils and the shorter the distance, the higher the efficiency.
According to some wireless charging specifications, the sizes of the TX and RX inductor coils 114 and 122 are both limited, for example, to a maximum size of 70 mm diameter, where diameter refers to the largest axial dimension. Note that the coils are generally circular. These maximum coil sizes limit the distance over which wireless power transfer can be achieved at a specified efficiency level. For example, with TX and RX inductor coils 114 and 122 at the 70 mm diameter limit, the power transfer efficiency is less than 40% at a distance of only 40 mm. Unfortunately, in some applications, it is desirable to perform wireless power transfer over a Z gap as large as about 100 mm, at which distance the power transfer efficiency of the conventional wireless power transfer system 100 would be unacceptably low. Accordingly, it is desirable to have a wireless power transfer system that can transfer power more efficiently at distances up to or even greater than 100 mm.
Embodiments of the present invention are illustrated by way of example and are not limited by the accompanying figures, in which like references indicate similar elements. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the thicknesses of layers and regions may be exaggerated for clarity.
Detailed illustrative embodiments of the present invention are disclosed herein. However, specific structural and functional details disclosed herein are merely representative for purposes of describing example embodiments of the present invention. Embodiments of the present invention may be embodied in many alternative forms and should not be construed as limited to only the embodiments set forth herein. Further, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments of the invention.
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. It further will be understood that the terms “comprises”, “comprising”, “has”, “having”, “includes”, or “including” specify the presence of stated features, steps, or components, but do not preclude the presence or addition of one or more other features, steps, or components. It also should be noted that, in some alternative implementations, the functions/acts noted might occur out of the order noted in the figures. For example, two figures shown in succession may in fact be executed substantially concurrently or may sometimes be executed in the reverse order, depending upon the functions/acts involved. The term “or” is to be interpreted as inclusive unless indicated otherwise.
To achieve higher power transfer efficiencies over larger Z-gap distances, the present invention provides a two-stage wireless power transfer system, where a relatively large Z-gap distance is spanned by the first stage, which has relatively large TX and RX inductor coils, while the second stage, which has a relatively small TX inductor coil, spans a relatively short Z-gap distance.
In one embodiment, the present invention is an article of manufacture comprising a second component for a two-stage wireless power transfer system. The power transfer system includes (i) a first component having a first wireless power transmitter (TX) of a first stage of the power transfer system, (ii) the second component, and (iii) a third component having a second wireless power receiver (RX) of a second stage of the power transfer system. The second component comprises a first wireless power receiver of the first stage configured to receive wireless power from the first wireless power transmitter of the first component and a second wireless power transmitter of the second stage connected to receive power from the first wireless power receiver and configured to transmit wireless power to the second wireless power receiver of the third component.
Referring now to
In a typical implementation, the two-stage power transfer system 20 would be implemented as three distinct components: (i) a first component 22 comprising the power transmitter 210(1) of the first stage 200(1); (ii) a second component 24 comprising both the power receiver 220(1) of the first stage 200(1) and the power transmitter 210(2) of the second stage 200(2); and (iii) a third component 26 comprising the power receiver 220(2) of the second stage 200(2). Note that the third component 26 typically is implemented within a consumer device being charged, such as a cell phone or other battery-powered device.
The primary structural difference between the first and second stages 200(1) and 200(2) of the two-stage system 20 is that the TX and RX inductor coils 214(2) and 222(2) in the second stage 200(2) conform to the maximum size requirement of the applicable wireless-charging specification, while the TX and RX inductor coils 214(1) and 222(1) in the first stage 200(1) are significantly larger than that maximum size, which allows them to be spaced further apart.
For example, in an application of the two-stage power transfer system 20 for charging cell phones in which the applicable specification limits the size of the RX inductor coil inside the cell phone to 70 mm diameter, the power receiver 220(2) of the second stage 200(2) is implemented inside the cell phone (i.e., the third component 26) with an RX inductor coil 222(2) no larger than 70 mm diameter, while the RX inductor coil 222(1) of the first stage 200(1) is implemented in the second component 24 and has a large diameter significantly greater than 70 mm. In addition, the second component 24 is implemented with a TX inductor coil 214(2) of the second stage 200(2) no larger than 70 mm diameter, while the TX inductor coil 214(1) of the first stage 200(1) is implemented in the first component 22 with a large diameter significantly greater than 70 mm. As such, the distance between the power transmitter 210(1) of the first stage 200(1) in the first component 22 and the power receiver 220(1) of the first stage 200(1) in the second component 24 may be relatively large, while the distance between the power transmitter 210(2) of the second stage 200(2) in the second component 24 and the power receiver 220(2) of the second stage 200(2) in the third component 26 is relatively small, while still achieving a sufficiently high overall power transfer efficiency.
Assume, for example, the desire to provide wireless cell phone charging on top of an existing conference room table or other structure made of a non-magnetic material. One option would be to deploy the conventional wireless power transfer system 100 of
A better option is to deploy the system 20 of the present invention, where the first component 22 having the power transmitter 210(1) of the first stage 200(1) is mounted on the bottom surface of the table, the second component 24 having the power receiver 220(1) of the first stage 200(1) and the power transmitter 210(2) of the second stage 200(2) is placed on the top surface of the table above the first component 22, and the third component 26 (i.e., the cell phone) having the power receiver 220(2) of the second stage 200(2) is place on top of the second component 24.
Although, in this configuration, the Z-gap distance between the power transmitter 210(1) of the first stage 200(1) and the power receiver 220(1) of the first stage 200(1) is more than 250 mm because the TX and RX inductor coils 214(1) and 222(1) are significantly larger than those allowed by the applicable specification, the power transfer efficiency of the first stage 200(1) is reasonably high. Furthermore, although the TX and RX inductor coils 214(2) and 222(2) of the second stage 200(2) are limited to the maximum size allowed by the applicable specification/standard, the power transfer efficiency of the second stage 200(2) also is reasonably high because the Z-gap distance between the power transmitter 210(2) of the second stage 200(2) and the power receiver 220(2) of the second stage 200(2) is relatively small with the cell phone placed right on top of the second component 24. Note that, even though the overall power transfer efficiency is the product of the power transfer efficiencies of the individual stages 200(1) and 200(2), the overall power transfer efficiency of the system 20 is higher than the power transfer efficiency of the conventional system 100 for large Z-gap situations.
For example, an implementation of the conventional power transfer system 100 having a 70 mm TX inductor coil 114 and an RX inductor coil 122 at the 70 mm diameter limit would have a power transfer efficiency of not higher than about 40% at a Z-gap distance of about 40 mm. Assume an implementation of the power transfer system 20 of
Note that in a typical implementation, the first component 22 is plugged into an AC “wall” socket and includes an AC-to-DC converter (not shown in
In some implementations, all the power needed to operate the second component 24 comes from the power transmitted wirelessly from the first component 22. In some alternative implementations, the second component 24 could have a battery that is charged by the power received from the first component 22, where that battery may be used to provide some of the power for operating the second component 24, while the power transmitted wirelessly to the third component 26 is directly based entirely or almost entirely on the power received wirelessly from the first component 22. In either case, the second component 24 is a wireless device that is not plugged into any hardline power supply, such as an AC wall socket.
As represented in
In general, the purpose of the shielding 304 and 308 is to protect other electronic components from the magnetic fields generated by the inductor coils. Thus, the shielding 304 in the first component 22 is designed to protect the electronic components in the control and communication unit 306 from the magnetic field generated by the TX inductor coil 214(1). Similarly, the shielding 308 in the second component 24 is designed to protect the electronic components in the control and communication unit 310 from the magnetic fields generated by both the RX inductor coil 222(1) and the TX inductor coil 214(2). Although not explicitly represented in
The Z-gap distance spanned by the first stage 200(1) of the two-stage power transfer system 20 is much greater than the Z-gap distance spanned by the second stage 200(2).
In some possible implementations, the second component 24 has a single TX inductor coil 214(2) such that only one wireless device 26 can be charged at a time. In other implementations, the second component 24 has multiple TX inductor coils 214(2) so that multiple wireless devices 26 can be charged simultaneously.
Although not explicitly shown in
Although the invention has been described in the context of the two-stage wireless power transfer systems 20 of
Although the invention is described herein with reference to specific embodiments, various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention. Any benefits, advantages, or solutions to problems that are described herein with regard to specific embodiments are not intended to be construed as a critical, required, or essential feature or element of any or all the claims.
It should be understood that the steps of the exemplary methods set forth herein are not necessarily required to be performed in the order described, and the order of the steps of such methods should be understood to be merely exemplary. Likewise, additional steps may be included in such methods, and certain steps may be omitted or combined, in methods consistent with various embodiments of the invention.
Although the elements in the following method claims, if any, are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.
Reference herein to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments necessarily mutually exclusive of other embodiments. The same applies to the term “implementation”.
Number | Date | Country | Kind |
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201910436774.1 | May 2019 | CN | national |