1. Technical Field
The disclosure relates generally to a method and apparatus for wireless power transmission.
2. Discussion of Technical Background
Wireless power transmission is the transmission of electrical energy from a power source to an electrical load without interconnecting manmade conductors. The most common form of wireless power transmission is carried out using direct induction followed by resonant magnetic induction. Other methods include electromagnetic radiation in the form of microwaves or lasers and electrical conduction. Wireless power transmission has been used for battery charging, or other suitable loads, in a wide range of mobile devices, such as mobile phone, camera, music player, headset, etc.
In a wireless power transmission system, the receiving device (receiver) may provide control information to the transmitting device (transmitter) by, for example, load modulation on the power signal. Based on the received control information, the transmitting device may adjust a certain parameter associated with the transmitted electric power, e.g., the frequency, to the desired level in order to drive the load coupled to the receiving device. Known standards, such as QI communication protocol (Wireless Power Consortium), define how the receiving device communicates its power needs back to the transmitting device over the same magnetic coupling used for power transmission. For example, after the initial communication between the receiving and transmitting devices is established at a default pulse-width-modulation (PWM) frequency of 175 kHz, load is immediately coupled to the receiving device. However, as the default PWM frequency is relatively high, the corresponding load driving capacity of the received electric power is relatively low. As the load, is immediately coupled to the receiving device, the rectified voltage may suddenly drop, which is undesirable for the receiving device. Moreover, as the current QI communication protocol supports up to 5 W of output power, if the load is 10 W or higher, the sudden voltage-drop may cause the receiving device fail to drive the load.
Accordingly, there exists a need for an improved solution for wireless power transmission to solve the above-mentioned problems.
The present disclosure describes methods, apparatus, and programming for wireless power transmission.
In one example, a method for a receiving device to wirelessly receive electric power from a transmitting device is provided. A first target level of a parameter associated with the electric power is sent to the transmitting device. The electric power is then received from the transmitting device. When the parameter of the received electric power reaches the first target level, a second target level of the parameter is sent to the transmitting device. The second target level of the parameter is determined based on a magnitude of a load coupled to the receiving device.
In another example, an apparatus including a receiving device is provided. The receiving device includes a power reception unit, a control unit, and a communication unit. The power reception unit is configured to wirelessly receive electric power from a transmitting device. The control unit is operatively coupled to the power reception unit and is configured to control sending of a first target level of a parameter associated with the electric power to the transmitting device. The control unit is further configured to, when the parameter of the received electric power reaches the first target level, control sending of a second target level of the parameter to the transmitting device. The second target level of the parameter is determined based on a magnitude of a load coupled to the receiving device. The communication unit is operatively coupled to the power reception unit and the control unit and is configured to send the first and second target levels of the parameter to the transmitting device.
In still another example, a system for wireless power transmission is provided. The system includes a receiving device and a transmitting device. The receiving device includes a power reception unit, a control unit, and a communication unit. The power reception unit is configured to wirelessly receive electric power from a transmitting device. The control unit is operatively coupled to the power reception unit and is configured to control sending of a first target level of a parameter associated with the electric power to the transmitting device. The control unit is further configured to, when the parameter of the received electric power reaches the first target level, control sending of a second target level of the parameter to the transmitting device. The second target level of the parameter is determined based on a magnitude of a load coupled to the receiving device. The communication unit is operatively coupled to the power reception unit and the control unit and is configured to send the first and second target levels of the parameter to the transmitting device. The transmitting device includes a power transmission unit configured to wirelessly transmit the electric power to the receiving device at a frequency determined based on the first and second target levels of the parameter.
In yet another example, a machine readable and non-transitory medium having information recorded thereon for wireless power transmission, wherein the information, when read by the machine, causes the machine to perform a series of steps. A first target level of a parameter associated with electric power is sent by a receiving, device to a transmitting device. The electric power is then wirelessly received by the receiving device from the transmitting device. When the parameter of the received electric power reaches the first target level, a second target level of the parameter is sent by the receiving device to the transmitting device. The second target level of the parameter is determined based on a magnitude of a load coupled to the receiving device.
The embodiments will be more readily understood in view of the following description when accompanied by the below figures and wherein like reference numerals represent like elements, wherein:
Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. While the present disclosure will be described in conjunction with the embodiments, it will be understood that they are not intended to limit the present disclosure to these embodiments. On the contrary, the present disclosure is intended to cover alternatives, modifications, and equivalents, which may be included within the spirit and scope of the present disclosure as defined by the appended claims.
Furthermore, in the following detailed description of embodiments of the present disclosure, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be recognized by one of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the embodiments of the present disclosure.
Embodiments in accordance with the present disclosure provide a method and apparatus for driving a large load by wireless power transmission. The method and apparatus disclosed herein can adaptively support loads with different power needs in a more efficient manner compared with known solutions. Moreover, the method and apparatus disclosed herein also support existing wireless power transmission standards, such as the QI communication protocol, and thus, are compatible with any QI-compatible transmitting device with 5 W power capacity.
Additional advantages and novel features will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and the accompanying drawings or may be learned by production or operation of the examples.
In this example, the receiving device 102 may be part of an apparatus 106 having a load 108 that can be coupled to be receiving device 102. The apparatus 106 may be any suitable electronic device, such as but is not limited to, a laptop computer, netbook computer, digital camera, digital camcorder, handheld device (e.g., dumb or smart phone, tablet, etc.), gaming, console, set-top box, music player, global positioning system (GPS), or any other suitable device. The load 108 may be, for example, a battery charger and one or more batteries. In other examples, the receiving device 102 may be a discrete electronic device for providing power to the load 108. In any event, a switch 110 may be provided between the receiving device 102 and the load 108 to control coupling of the load 108 to the receiving device 102. It is understood that any other suitable component may be included in the apparatus 106.
In this example, the receiving device 102 includes a power reception unit 112, a control unit 114, and a communication unit 116. The power reception unit 112 is configured to wirelessly receive electric power from the transmitting device 104. The control unit 114 in this example performs various control functions, such as monitoring and analyzing the electrical parameters associated with the received electric power against desired operation points e.g., output current, voltage) and controlling the power provided to the output load 108. The control unit 114 is also configured to control sending of target levels of electrical parameters associated with the electric power to the transmitting device 104 by the communication unit 116. That is, the control unit 114 is responsible for sending its power needs back to the transmitting device 104. The communication unit 116 is configured to send control information to the transmitting device 104 in accordance with a communication protocol, such as the QI communication protocol, for example, by the same electromagnetic coupling mechanism used for power transmission. The control information in this example includes target levels of the electrical parameters associated with the electric power.
The transmitting device 104 may be any suitable base station for wirelessly providing electric, power to the receiving device 102. In this example, the transmitting device 104 includes a power transmission unit 118, a control unit 120, and a communication unit 122. The power transmission unit 118 is configured to wirelessly transmit the electric power to the receiving device 102 at a certain PWM frequency. The frequency is determined by the control unit 120 based on the received target levels of the electrical parameters sent from the receiving device 102. The communication unit 122 is configured to receive the control information including the target levels of the electrical parameters from the receiving device 102.
In this example, after the initial communication between the transmitting and receiving devices 104, 102 is established, the control unit 114 of the receiving device 102 first controls the switch 110 to decouple the load 108 from the receiving device 102. The control unit 114 of the receiving device 102 then sends a first target level of a parameter associated with the electric power to the transmitting device 104. The first target level of the parameter, such as the desired output voltage, is determined regardless of the magnitude of the load 108 as it is decoupled from the receiving device 102. Upon receiving the first target level, the control unit 120 of the transmitting device 104 controls the power transmission unit 118 to adjust the PWM frequency of the transmitted electric power accordingly. The control unit 114 of the receiving device 102 then continually monitors the detected level of the parameter to see if it reaches the first target level. Once the first target level is reached, the control unit 114 is further configured to control the switch 110 to couple the load 108 to the receiving device 102 and determine a second target level of the parameter based on the magnitude of the load 108 (e.g., load current). The second target level is sent to the transmitting device 104 and used for adaptively adjusting the PWM frequency based on the magnitude of the load 108.
In this example, the target level of the electric parameter may be a predetermined value regardless of the magnitude of the load or a value adaptively determined based on the magnitude of the load once it is coupled to the receiving device 102 through the switch 110. In one example, as shown in
The transmitting device 104 then adjusts the PWM frequency of the transmitted electric power to a level that is determined based on the first target level of the parameter. In the example mentioned above, the transmitting device 104 may try to adjust its PWM frequency to 160 kHz such that the output voltage of the receiving device 102 may reach the first target level. The electric power is then transmitted to the receiving device 102 at the frequency determined based on the first target level.
In this example, once the parameter reaches the first target level at the receiving device 102, the load 108 is then coupled to the receiving device 102. Based on the actual magnitude of the load 108, the receiving device 102 determines a second target level of the parameter, e.g., output voltage, which is sufficient to drive the load 108. The second target level of the parameter is sent to the transmitting device 104 so that the transmitting device 104 may adjust the PWM frequency accordingly. The electric power is then transmitted to the receiving device 102 at the frequency determined based on the second target level.
It is understood that the first target level of output voltage may be set up to be higher than the second target level. Accordingly, the receiving device 102 has a higher load driving capacity without coupling the load in order to avoid any sudden voltage-drop and then reduces its output voltage according to the actual magnitude of the load 108 once the load 108 is coupled in order to increase its efficiency. By doing so, the receiving device 102 is able to adaptively drive loads with a wide range of magnitudes while still being compatible with existing standards, such as the QI communication protocol. The sudden voltage-drop happened in known solutions is also suppressed as the load 108 is not coupled to the receiving device 102 until the output voltage reaches a desired level.
At block 710, whether the electrical parameter reaches the first target level within a predetermined time period is determined. As described above, this may be performed by control unit 114 of the receiving device 102. If the electrical parameter reaches the first target level within the first time period, process continues to block 712, where the load is coupled to the receiving device. As described above, this may be performed by the control unit 114 of the receiving device 102 in conjunction with the switch 110. At block 714, the magnitude of the load, e.g., load current, is detected. Moving to block 716, the second target level of the electrical parameter is determined based on the detected load magnitude. For example, the electrical parameter may be output voltage, and the first target level of the output voltage is higher than the second target level of the output voltage. As described above, blocks 714, 716 may be performed by the control unit 114 of the receiving device 102. At block 718, the second target level of the electrical parameter is sent to the transmitting device. As described above, this may be performed by control unit 114 in conjunction with the communication unit 116 of the receiving device 102. At block 720, electric power with a frequency determined based on the second target level of the parameter is received. The frequency may be adjusted by the transmitting device according to the second target level of the parameter. As described above, this may be performed by the power reception unit 112 of the receiving device 102.
Aspects of the method for wireless power transmission, as outlined above, may be embodied in programming. Program aspects of the technology may be thought of as “products” or “articles of manufacture” typically in the form of executable code and/or associated data that is carried on or embodied in a type of machine readable medium. Tangible non-transitory “storage” type media include any or all of the memory or other storage for the computers, processors or the like, or associated modules thereof, such as various semiconductor memories, tape drives, disk drives and the like, which may provide storage at any time for the computer-implemented method.
All or portions of the computer-implemented method may at times be communicated through a network such as the Internet or various other telecommunication networks. Such communications, for example, may enable loading of the software from one computer or processor into another. Thus, another type of media that may hear the elements of the computer-implemented method includes optical, electrical, and electromagnetic waves, such as used across physical interfaces between local devices, through wired and optical landline networks and over various air-links. The physical elements that carry such waves, such as wired or wireless links, optical links or the like, also may be considered as media bearing the computer-implemented method. As used herein, unless restricted to tangible “storage” media, terms such as computer or machine “readable medium” refer to any medium that participates in providing instructions to a processor for execution.
Hence, a machine readable medium may take many forms, including but not limited to, a tangible storage medium, a carrier wave medium or physical transmission medium. Non-volatile storage media include, for example, optical or magnetic disks, such as any of the storage devices in any computer(s) or the like, which may be used to implement the system or any of its components as shown in the drawings. Volatile storage media include dynamic memory, such as a main memory of such a computer platform. Tangible transmission media include coaxial cables; copper wire and fiber optics, including the wires that form a bus within a computer system. Carrier-wave transmission media can take the form of electric or electromagnetic signals, or acoustic or light waves such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media therefore include for example: a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD or DVD-ROM, any other optical medium, punch cards paper tape, any other physical storage medium with patterns of holes, a RAM, a PROM and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave transporting data or instructions, cables or links transporting such a carrier wave, or any other medium from which a computer can read programming code and/or data. Many of these forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to a processor for execution.
Those skilled in the art will recognize that the present disclosure is amenable to a variety of modifications and/or enhancements. For example, although the implementation of various components described above may be embodied in a hardware device, it can also be implemented as a firmware, firmware/software combination, firmware/hardware combination, or a hardware/firmware/software combination.
While the foregoing description and drawings represent embodiments of the present disclosure, it will be understood that various additions, modifications, and substitutions may be made therein without departing from the spirit and scope of the principles of the present disclosure as defined in the accompanying claims. One skilled in the art will appreciate that the present disclosure ma be used with many modifications of form, structure, arrangement, proportions, materials, elements, and components and otherwise, used in the practice of the disclosure, which are particularly adapted to specific environments and operative requirements without departing from the principles of the present disclosure. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the present disclosure being indicated by the appended claims and their legal equivalents, and not limited to the foregoing description.