Patent Application
20160118805
The present disclosure relates generally to a power transfer system and more particularly to a system and method for providing wireless power transfer between devices.
Portable radios such as battery operated hand-held radios are utilized within a variety of public safety environments, such as law enforcement, fire rescue, and emergency medical environments to name a few. Public safety personnel working in the field often carry a number of accessories for their day to day operation. However, it is not always possible for public safety personnel working in unfavorable conditions to find power supplies or carry enough batteries to power the accessories.
Accordingly, there is a need for an efficient mechanism to supply power for one or more devices carried by personnel working in fields.
The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views, together with the detailed description below, are incorporated in and form part of the specification, and serve to further illustrate embodiments of concepts that include the claimed invention, and explain various principles and advantages of those embodiments.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.
A wireless power transfer system and method is provided. The system includes a source coil that is coupled to a power supplying device and a receiver coil that is coupled to a power receiving device. In operation, when the source coil is energized by the power supplying device and the receiver coil is positioned within a predetermined range of distances from the source coil, the receiver coil is inductively coupled to the source coil at a predefined magnetic resonance frequency to wirelessly transfer power from the power supplying device to the power receiving device. The power receiving device measures a voltage level corresponding to the power transferred therein and sends information pertaining to the voltage level to the power supplying device. In response, the power supplying device adjusts voltage at the source coil based on comparing the voltage level with a predetermined threshold determined for the power receiving device.
The wireless power transfer system 100 further comprises a source coil 130 and a receiver coil 140. The wireless power transfer operation between the power supplying device 110 and power receiving device 120 is achieved by implementing a source coil 130 at the power supplying device 110 and a receiver coil 140 at the power receiving device 120. The source coil 130 and receiver coil 140 may take form of an electrical conductor (e.g. an inductor) such as a wire in the shape of a coil, spiral, or helix that is capable of generating a magnetic field when an electrical current is passed through it. During the wireless power transfer operation, the source coil 130 is capable of wirelessly transferring power to the receiver coil 140 when the source coil 130 is energized by the power supplying device 110 and further when the receiver coil 140 is positioned within a predetermined range of distances (for example, within a tolerance range of 0-200 meters) from the source coil 130. In one embodiment, the source coil 130 is required to resonate at the same frequency (a predetermined magnetic resonant frequency) as that of the receiver coil 140 to inductively couple to the receiver coil 140 and wirelessly transfer power between the power supplying device 110 and power receiving device 120. In order for the power transfer to be efficient between the source coil 130 and receiver coil 140, a strongly coupled magnetic resonance (SCMR) frequency is used in the embodiments of the present disclosure to produce a SCMR coupling 150 between the source coil 130 and the receiver coil 140. As used herein, the term ‘SCMR frequency’ refers to a frequency at which both the source coil 130 and the receiver coil 140 are inductively coupled to achieve a maximum possible efficiency in the transfer of electrical energy between the power supplying device 110 and power receiving device 120. The SCMR frequency used to achieve maximum energy transfer efficiency varies between devices, and can depend on multiple factors such as size, shape, material, number of coil windings of the source coil 130 and receiver coil 140, operating voltage of the power supplying device 110 and power receiving device 120, power supply capacity of the power supplying device 110, energy transmission/storage capacity of the power receiving device 120, distance between the power supplying device 110 and power receiving device 120, environmental factors (interference), and the like. In one embodiment, when the power supplying device 110 is a public safety portable radio device used in land mobile radio (LMR) communication systems and the power receiving device 120 is a public safety accessory device used to support LMR communication, the SCMR frequency is predetermined to be within a tolerance range of 6.78 MHz to achieve a maximum possible efficiency during the wireless power transfer operation between such devices.
In public safety environments, portable radio devices/battery packs (power supplying devices 110) can be adapted to function as a wireless charger for a number of accessory devices (power receiving devices 120) such as remote speaker microphones, integrated glass displays, sensors such as proximity sensors, biometric sensors, gun holster sensors, or environmental sensors, or other collaborative electronic accessory devices supporting public safety broadband communication and mission critical applications. However, this situation requires utilizing a limited power supply source (such as a battery pack) or a battery powered device (such as a portable radio device) as the power supplying device 110 to charge devices/accessories which may further drain the limited power capacity of the power supplying device 110. The embodiments of the present disclosure described herein provide a solution to manage the power drain of the power supplying device 110 and also address an overvoltage condition of the power receiving device 120 during the wireless power transfer operation between such devices. In one embodiment, the power supplying device 110 adjusts voltage at the source coil 130 to provide power transfer capability in response to external voltage information such as an overvoltage condition at the power receiving device 120. In this embodiment, the power supplying device 110 reduces the voltage at the source coil 130 when a voltage level measured at the receiver coil 140 is greater than a predetermined threshold level determined for the power receiving device 120. Otherwise, the power supplying device 110 maintains the voltage at the source coil 130 when the voltage level measured at the receiver coil 140 is not greater than the predetermined threshold level determined for the power receiving device 120. This regulation or maintenance of voltage at the source coil 130 in response to voltage condition at the receiver coil 140 ensures that the power supplying device 110 is not providing more power than required by the power receiving device 120 at any given time.
The power receiving device 120 communicates information pertaining to the voltage level measured at the receiver coil 140 using the short range wireless connection. In one embodiment, the power drain in the power supplying device 110 is managed by de-energizing the source coil 130 whenever it is determined that the voltage at the source coil 130 has already reached a maximum operating voltage, which indicates that the power supplying device 110 is unable to satisfy the power requirements (for example, voltage requirement) of the power receiving device 120 even with the application of maximum operating voltage at the source coil 130. In one embodiment, the source coil 130 is de-energized when the power supplying device 110 receives information indicating that the power requirements of the power receiving device 120 is fully satisfied (e.g. when the power receiving device 120 is fully charged). This ensures that the power capacity of the power supplying device 110 is not unnecessarily drained as the source coil 130 is maintained in an energized state only as long as the power supplying device 110 continues to satisfy the power requirements of the power receiving device 120.
The RF power amplifier 250 is configured to increase power of a signal coupled to an input of the RF power amplifier 250. In one embodiment, the RF power amplifier 250 is configured to amplify a modulated baseband signal coupled to an input of the RF power amplifier 250 to produce an RF output signal to allow the portable radio system 200 to function in RF communication mode for establishing long range wireless communication with other devices. In accordance with embodiments of the present disclosure, the radio controller 220 controls the switch 240 to connect the power control circuit 230 to the RF power amplifier 250. This allows the RF power amplifier 250 to draw a first supply voltage from the power control circuit 230 and further energize an antenna coupled to the RF power amplifier 250 during RF communication mode. In one embodiment, when the portable radio system 200 is used to support LMR communication systems, the first supply voltage is within a predetermined tolerance range of 25-35 volts. When the radio controller 220 receives a request for wireless charging or power transfer from at least one other device, for example, power receiving device 120 via short range wireless communications means 360, the radio controller 220 controls the switch 240 to switch a connection of the power control circuit 230 to the source coil 130 and further controls the power control circuit 230 to increase the output supply voltage from the first supply voltage (used for RF communication mode, for example 28 volts) to a second supply voltage (used for wireless charging mode, for example 48-50 volts) to energize the source coil 130. In this embodiment, the energization of the source coil 130 with the second supply voltage inductively couples the source coil 130 to the receiver coil 140 at a predefined magnetic resonance frequency (i.e. at SCMR frequency) to allow power transfer from the power supplying device 110 to the power receiving device 120. In one embodiment, when the portable radio system 200 is used to provide wireless power transfer to public safety accessory devices, the second supply voltage is within a predetermined tolerance range of 45-55 volts. In another embodiment, when the portable radio system 200 includes a power supply source that is capable of providing large power capacity, the second supply voltage can be increased to a value between 50-100 volts to provide wireless power transfer to devices having high energy requirements.
The tuning control 260 includes tuning circuits that are controlled by the radio controller 220 to select resistance and capacitance values that are required to resonate the source coil 130 at the predefined magnetic resonance frequency. The short range wireless communication means 270 includes various protocols and components that are required to establish short range wireless connection with other devices such as the power receiving device 120 to exchange messages necessary for performing the wireless power transfer operation. In one embodiment, the short range wireless communication means 270 includes a short range wireless transceiver and antenna that operates at low power to perform short range wireless communication with other devices. In one embodiment, the short range wireless communication means 270 employs one or more low power wireless technologies including, but not limited to Bluetooth®, Wi-Fi, IEEE 802.15 standards, and near-field communication (NFC). In accordance with embodiments of the present disclosure, the short range wireless communication means 270 enables the power supplying device 110 to receive power transfer request from the power receiving device 120, send an acknowledgment for the power transfer request to the power receiving device 120, receive an acknowledgment that the power transfer or charging is occurring at the power receiving device 120, receive information pertaining to a voltage level (such as overvoltage condition) measured at the receiver coil 140 from the power receiving device 120 during the wireless power transfer operation, and receive an indication from the power receiving device 120 when the charging or power transfer at the power receiving device 120 is complete.
In one embodiment, when the radio controller 220 receives a request for power transfer from the power receiving device 120, the radio controller 220 determines whether the power supplying device 110 can meet the power requirements of the power receiving device 120 and sends an acknowledgment via the short range wireless communication means 270 if it can wirelessly transfer power while meeting the power requirements of the power receiving device 120. In one embodiment, the radio controller 220 requests for device configuration parameters such as battery capacity, operating voltage, operating frequency, and other device specific parameters from the power receiving device 120. In one embodiment, the radio controller 220 maintains device configuration parameters for a list of devices which are either stored locally or remotely in a database. The radio controller 220 uses the device configuration parameters to determine whether the power supplying device 110 can satisfactorily meet the power requirements of the power receiving device 120, and also further determine a threshold level (herein after referred to as a predetermined threshold level) for comparison with voltages measured at the receiver coil 140. The radio controller 220, after sending the acknowledgment for the power transfer request via the short range wireless communication means 270 to the power receiving device 120, controls the switch 240 to switch the connection of the power control circuit 230 to the source coil 130 and further control the power control circuit 230 to increase the output supply voltage to the second supply voltage that is required to energize the source coil 130.
When the source coil 130 is energized at a predefined magnetic resonance frequency and the receiver coil 140 is positioned within the predetermined range of distances from the source coil 130, the source coil 130 is inductively coupled to the receiver coil 140 to wirelessly transfer power from the power supplying device 110 to the power receiving device 120. In response, the power supplying device 110 receives via the short range wireless communication means 270, information pertaining to a voltage level measured at the receiver coil 140 corresponding to the wireless transfer of power at the power receiving device 120. If the voltage level measured at the receiver coil 140 is greater than the predetermined threshold level for the power receiving device 120, the radio controller 220 controls the power control circuit 230 to reduce the second supply voltage by a predetermined level (for example, 5-10 volts at a time) to avoid overvoltage condition at the power receiving device 120. On the other hand, if the voltage level is not greater than the predetermined threshold level for the power receiving device 120, the radio controller 220 controls the power control circuit 230 to maintain the second supply voltage at the same level. However, if the voltage level is zero or falls within a range of smaller values relative to the predetermined threshold level or if the radio controller 220 receives information via short range wireless communication means 270 that the power transfer is not occurring at the power receiving device 120, the radio controller 220 controls the power control circuit 230 to increase the second supply voltage by a predetermined level to cause power transfer to the power receiving device 120.
At any point in time during the wireless power transfer operation, if the voltage at the source coil 130 has reached its maximum operating voltage or if the radio controller 220 receives indication via the short range wireless communication means 270 that the power requirements of the power receiving device 120 is fully met (i.e. power transfer or charging is complete), the radio controller 220 controls the power control circuit 230 to de-energize the source coil 130. In one embodiment, the radio controller 220 further controls the switch 240 to switch the connection of the power control circuit 230 back to the RF power amplifier 250. In one embodiment, during the wireless power transfer operation, if the radio controller 220 receives a signal to operate in RF communication mode, then the radio controller 220 controls the switch 240 to switch the connection of the power control circuit 230 back to the RF power amplifier 250 in order to operate in RF communication mode. In this embodiment, the radio controller 220 is programmed to provide higher priority for operating in RF communication mode of operation instead of wireless power transfer operation. In portable radio systems supporting LMR communication standards, the duty cycle of a portable radio device typically involves 5% of transmission time, 5% of reception time, and 90% of standby time. In such systems, the embodiments of the present disclosures can be advantageously implemented to provide wireless charging capability to the portable radio device during their (90%) standby time. In one embodiment, the radio controller 220 is programmed to control power control circuit 230 to apply an output supply voltage of 28 volts at less than 1 ampere of current to the RF power amplifier 250 during 5% of transmission time.
The receiver coil 140 resonates at the same predefined magnetic resonance frequency as that of the source coil 130 and receives power from the source coil 130 through the SCMR coupling 150 (see
The short range wireless communication means 360 is similar to short range wireless communication means 270 shown in
The device controller 320 is configured to detect a user input requesting to wirelessly charge the accessory device 300 via the portable radio system 200 and establish a short range wireless connection with the power supplying device 110 of the portable radio system 200 to initiate the wireless power transfer operation. The device controller 320 sends a wireless power transfer request to the power supplying device 110 via the short range wireless connection means 360. In response to the wireless power transfer request, the device controller 320 receives an acknowledgment via the short range wireless communication means 360 from the power supplying device 110 that confirms whether the power supplying device 110 can satisfy the power requirements of the power receiving device 120. In one embodiment, when the device controller 320 receives an acknowledgment that confirms that the power supplying device 110 can satisfy the power requirements of the power receiving device 120, the device controller 320 energizes the receiver coil 140 to resonate at the predefined magnetic resonance frequency of the source coil 130 in order to wirelessly transfer power from the source coil 130 to the receiver coil 140 through the SCMR coupling 150. In response to detecting SCMR coupling 150 between the source coil 130 and receiver coil 140, the device controller 320 measures a voltage level at the receiver coil 140 to determine if the power transfer or charging is occurring at the power receiving device 120. In one embodiment, if no power transfer or charging is occurring at the power receiving device 120 (i.e. if voltage level is zero or falls within a range of smaller values relative to the predetermined threshold for the power receiving device 120), the device controller 320 sends an acknowledgment to the power supplying device 110 to indicate that no power transfer is occurring at the power receiving device 120. This acknowledgment allows the power supplying device 110 to either increase the voltage at the source coil 130 up to its maximum operating voltage to cause power transfer or discontinue the wireless power transfer operation by de-energizing the source coil 130 if power transfer is not possible. In another embodiment, if the device controller 320 detects that no power transfer is occurring, the device controller 320 provides an alert to the user to correct or adjust the position of the receiver coil 140 of the power receiving device 120 relative to the source coil 130 of the power supplying device 110.
Alternatively, if the device controller 320 detects that the power transfer is occurring at the power receiving device 120 i.e. if it detects the presence of voltage at the receiver coil 140, the device controller 320 sends information pertaining to the voltage level measured at the receiver coil 140 to the power supplying device 110. This information allows the power receiving device 120 to reduce or maintain the voltage supplied to the source coil 130 based on whether an overvoltage condition (i.e a condition when measured voltage is greater than the predetermined threshold level) is occurring or not at the power receiving device 120. The device controller 320 is further configured to detect when the power requirements of the power receiving device 120 is fully satisfied (for example, when the charging of the device battery 310 is complete) and send an indication via the short range wireless communication means 360 to the power supplying device 110. This indication allows the power supplying device 110 to discontinue the wireless power transfer operation by de-energizing the source coil 130.
When the power supplying device 110 determines at block 410 that the accessory device 300 is requesting to be charged, the method 400 proceed to block 415 where the power supplying device 110 checks whether the accessory device 300 includes TEDS. The power supplying device 110 captures TEDS information at block 420 if the accessory device 300 includes TEDS information containing the device configuration parameters. Otherwise, at block 425, the power supplying device 110 identifies a device type of the power receiving device 120 and extracts device configuration parameters corresponding to the device type from a device database 430. Next, at block 435, the power supplying device 110 sets up the device configuration parameters including operating frequency (FQ) and operating voltage (Vcoil) for the accessory device 300 and further determines a voltage threshold level for the accessory device 300. The power supplying device 110 energizes the source coil 130 at block 440. In one embodiment, when the power supplying device 110 of the portable radio system 200 supports long range wireless communication, the power control circuit 230 (see
The power supplying device 110, at block 445, determines whether charge is occurring at the accessory device 300. In one embodiment, the power supplying device 110 receives an acknowledgment from the accessory device 300 which indicates whether charge is occurring at the accessory device 300. In one embodiment, the power supplying device 110 receives information pertaining to a voltage level measured at the receiver coil 140 from the accessory device 300. When the voltage level at the receiver coil 140 is zero or falls within a range of smaller values (for example 0-10 volts) relative to the predetermined threshold level (for example, 50 volts), the power supplying device 110 determines that charge is not occurring at the accessory device 300. When the power supplying device 110 determines that the accessory device 300 is not being charged through the SCMR coupling 150, the method 400 proceeds to block 450 where the power supplying device 110 increases the voltage that is applied at the source coil 130 by a predetermined level to cause the power transfer from the power supplying device 110 to the accessory device 300. Next, at block 455, the power supplying device 110 determines whether the voltage applied at the source coil 130 has reached maximum operating voltage of the source coil 130. When the voltage applied at the source coil 130 has reached the maximum operating voltage, the power supplying device 110 de-energizes the source coil 130 to avoid draining its power capacity. In one embodiment, it is possible that the distance between the source coil 130 and the receiver coil 140 may be more than the predetermined range of distances that is required for effecting SCMR coupling 150 between the source coil 130 and 140. In such situations, the power transfer to the accessory device 300 may not be possible even with the application of voltage that is closer to maximum operating voltage at the source coil 130 until the source coil 130 and receiver coil 140 are positioned within the predetermined range of distances required for effecting SCMR coupling. Returning to block 455, when the voltage applied at the source coil 130 has not reached the maximum operating voltage, the method 400 continues to check whether charging is occurring at the accessory device 300 (as described in block 445) and increase voltage applied at the source coil 130 (as described in block 450) up to its maximum operating voltage or until it receives a positive acknowledgment indicating that charge is occurring at the accessory device 300.
Returning to block 445, when the power supplying device 110 determines that the charging is occurring at the accessory device 300, the method proceeds to block 465 where the power supplying device 110 determines whether the voltage level (referred to as device voltage in
Returning to block 475, when the power supplying device 110 determines that the charging is not completed at the accessory device 300, the power supplying device 110 determines whether it has received any interrupt either from within the device or from the accessory device 300 that requests for the wireless charging to be discontinued. In one embodiment, the power supplying device 110 may receive the interrupt when there is a user input requesting to discontinue the charging operation or when its battery capacity falls below a predetermined power threshold level or when the device needs to be switched for operation in RF communication mode. For example, as shown in block 485, the power supplying device 110 checks whether it needs to continue to charge the accessory device 300. When the power supplying device 110 receives an interrupt that requests for the wireless charging operation to be discontinued, the method proceeds to block 480 where the power supplying device 110 terminates the charge and de-energizes the source coil 130 at block 460. Otherwise, the method proceeds to block 465 and continues to perform the wireless charging operation until the charging at the accessory device 300 is completed or it receives an interrupt that request for charging operation to be discontinued.
As show in
Embodiments of the present disclosure described above with reference to
Embodiments of the present disclosure also adapt a portable radio (for example, a portable radio using a 28V power amplifier design) to function as a wireless charger with minimal changes in the existing circuitry of the portable radio. This ensures that the same power supply electronics used in existing two-way portable and mobile radios can be used to power an accessory device. Embodiments of the present disclosure implement a switch in the portable radio that allows the portable radio to switch between RF communication mode and wireless charging mode. The charging mode is enabled when the portable radio is in standby mode and not involved in RF communication.
In the foregoing specification, specific embodiments have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the 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 present teachings.
The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.
Moreover in this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” “has”, “having,” “includes”, “including,” “contains”, “containing” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises, has, includes, contains a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “comprises . . . a”, “has . . . a”, “includes . . . a”, “contains . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises, has, includes, contains the element. The terms “a” and “an” are defined as one or more unless explicitly stated otherwise herein. The terms “substantially”, “essentially”, “approximately”, “about” or any other version thereof, are defined as being close to as understood by one of ordinary skill in the art, and in one non-limiting embodiment the term is defined to be within 10%, in another embodiment within 5%, in another embodiment within 1% and in another embodiment within 0.5%. The term “coupled” as used herein is defined as connected, although not necessarily directly and not necessarily mechanically. A device or structure that is “configured” in a certain way is configured in at least that way, but may also be configured in ways that are not listed.
It will be appreciated that some embodiments may be comprised of one or more generic or specialized processors (or “processing devices”) such as microprocessors, digital signal processors, customized processors and field programmable gate arrays (FPGAs) and unique stored program instructions (including both software and firmware) that control the one or more processors to implement, in conjunction with certain non-processor circuits, some, most, or all of the functions of the method and/or apparatus described herein. Alternatively, some or all functions could be implemented by a state machine that has no stored program instructions, or in one or more application specific integrated circuits (ASICs), in which each function or some combinations of certain of the functions are implemented as custom logic. Of course, a combination of the two approaches could be used.
Moreover, an embodiment can be implemented as a computer-readable storage medium having computer readable code stored thereon for programming a computer (e.g., comprising a processor) to perform a method as described and claimed herein. Examples of such computer-readable storage mediums include, but are not limited to, a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a ROM (Read Only Memory), a PROM (Programmable Read Only Memory), an EPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically Erasable Programmable Read Only Memory) and a Flash memory. Further, it is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions and programs and ICs with minimal experimentation.
The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.
