Controller-managed charging current within thermal budget

Abstract

A method includes obtaining, by a controller of a computing device, a present temperature of an outer surface of the computing device while a battery of the computing device is being charged. The method further includes determining, by the controller and based on the present temperature of the outer surface of the computing device and a target temperature of the outer surface of the computing device, a charging current for the battery and system of the computing device. The method further includes causing, by the controller, the battery to charge with the determined charging current.

Description

CONTROLLER-MANAGED CHARGING CURRENT WITHIN THERMAL BUDGETBACKGROUND

[0001] Computing devices, such as smartphones, laptops, wearable devices, and tablets, may include wireless charging capabilities. Computing devices may operate as wireless charging source devices that wirelessly provide power or wireless charging sink devices that wirelessly receive power. For instance, a wireless charging sink device may include a receiver coil and other components capable of transducing a magnetic field into an electrical power signal that may be used to charge a battery of the computing device or otherwise operate components of the computing device. Similarly, a wireless charging source device may include a power supply that outputs a signal to a transmitter coil that causes the transmitter coil to generate a magnetic field.SUMMARY

[0002] In general, aspects of this disclosure are directed to an electronic device that adjusts battery charging current based on an outer surface temperature and system load of the electronic device. While some electronic devices may adjust charging current based on internal temperature (e.g., battery temperature), outer surfaces of the electronic devices may still become undesirably hot.

[0003] In accordance with one or more aspects of this disclosure, an electronic device may determine a charging current of the electronic device based on an external surface temperature and system load of the electronic device. For instance, a controller of the electronic device may adjust the charging current based on the external surface temperature to maximize charging current without the exterior of the electronic device getting too hot. In some examples, the controller may use a relatively small step size when adjusting the current (e.g., steps of less than 10% of a maximum charging current). In this way, the electronic device may maximize charging current while staying within a thermal budget.

[0004] In one example, a method comprises obtaining, by a controller of a computing device, a present temperature of an outer surface of the computing device while a battery of the computing device is being charged; determining, by the controller and based on the present temperature of the outer surface of the computing device and a target temperature of the outer surface of the computing device, a charging current for the battery and systemof the computing device; and causing, by the controller, the battery to charge with the determined charging current.

[0005] In another example, a computing device includes a battery and one or more programmable processors, and configured to obtain a present temperature of an outer surface of the computing device while the battery of the computing device is being charged; determine, based on the present temperature of the outer surface of the computing device and a target temperature of the outer surface of the computing device, a charging current for the battery of the computing device; and cause the battery to charge with the determined charging current.

[0006] In another example, a non-transitory computer-readable medium is encoded with instructions that, when executed, cause one or more processors of a computing device to obtain a present temperature of an outer surface of the computing device while the battery of the computing device is being charged; determine, based on the present temperature of the outer surface of the computing device and a target temperahire of the outer surface of the computing device, a charging current for the battery of the computing device; and cause the battery to charge with the determined charging current.

[0007] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.BRIEF DESCRIPTION OF DRAWINGS

[0008] FIG. 1 is a block diagram illustrating a system that includes a wireless charging source device and a wireless charging sink device, in accordance with one or more aspects of this disclosure.

[0009] FIG. 2 is a block diagram illustrating an example electronic device with a charging controller, in accordance with one or more aspects of this disclosure.

[0010] FIG. 3 is a flowchart illustrating an example charging operation of an electronic in accordance with one or more aspects of this disclosure.

[0011] FIGS. 4A-4F are example graphs showing parameters of various charging techniques, in accordance with one or more aspects of this disclosure.

[0012] FIG. 5 is a flowchart illustrating an example operation of a computing device in accordance with one or more aspects of this disclosure.DETAILED DESCRIPTION

[0013] FIG. 1 is a block diagram illustrating a system that includes a wireless charging source device and a wireless charging sink device in accordance with one or more aspects of this disclosure. As shown in FIG. 1, system 100 may include wireless charging source device 102 (“source device 102”) and wireless charging sink device 104 (“sink device 104”).

[0014] Source device 102 may be any type of device that wirelessly provides power to another device. Examples of source device 102 include, but are not limited to, a charging pad, a charging stand, an alarm clock, a power bank, a mobile phone, a camera device, a tablet computer, a smart display, a laptop computer, a desktop computer, a gaming system, a media player, an e-book reader, a television platform, a vehicle infotainment system or head unit, a vehicle surface with integrated charging, or a wearable computing device. As shown in FIG. 1, source device 102 may include wireless charging (WLC) transmitter 106 and power source 114.

[0015] Power source 114 may be any component capable of providing electrical power to other components of source device 102. Examples of power source 114 include, but are not limited to, batteries, solar panels, wall adapters, wireless charging receive coils, etc. As shown in FIG. 1, power source 114 may provide electrical power (e.g., direct current (DC) electrical power) to WLC transmitter 106.

[0016] WLC transmitter 106 may be configured to wirelessly provide power to another device. In some examples, WLC transmitter 106 may be compliant with (e.g., operate in accordance with) a wireless charging standard such as the Qi specification published by the Wireless Power Consortium (e.g., available at https: / / www.wirelesspowerconsortium.com / knowledge-base / specifications / download-the- qi-specifications / ). As shown in FIG. 1 , WLC transmitter 106 may include power converter 116 and transmitter (Tx) coil 118.

[0017] Power converter 116 may be configured to convert a direct current (DC) signal into an alternating current (AC) signal (e.g., to energize Tx coil 118). For instance, power converter 116 may convert a DC power signal received from power source 114 into an AC power signal, and provide the AC power signal to Tx coil 118. In some examples, power converter 116 may be an active full-bridge or half-bridge power converter that includes a plurality of switches. Operation of the plurality of switches may be controlled by a controller.

[0018] Tx coil i 18 may be configured to generate a magnetic field proportional to a power signal flowing through Tx coil 118. For instance, Tx coil 118 may generate a magnetic field having properties proportional to the AC power signal output to Tx coil 118 from power converter 116.

[0019] Sink device 104 may be any type of device that operates at least in part using power wirelessly received from another device. Examples of sink device 104 include, but are not limited to, a power bank, a mobile phone, a camera device, a stylus, a tablet computer, a smart display, a laptop computer, a desktop computer, a gaming system, a media player, an e-book reader, a television platform, or a wearable computing device. As shown in FIG. 1, sink device 104 may include wireless charging (WLC) receiver 108, charger 110, battery 112, and housing 126.

[0020] WLC receiver 108 may be configured to wirelessly receive power from another device. In some examples, WLC receiver 108 may be compliant with (e.g., operate in accordance with) a wireless charging standard such as the Qi specification published by the Wireless Power Consortium (e.g., available at wirelesspowerconsortium.com / knowledge-base / specifications / download-the-qi- specifications.html). As shown in FIG. 1, WLC receiver 108 may include receiver (Rx) coil 122, and rectifier 124.

[0021] Rx coil 122 may be configured to transduce a magnetic field into a power signal. For instance, Rx coil 122 may transduce the magnetic field generated by Tx coil 118 into an AC power signal having properties proportional to the magnetic field (e.g., and thus proportional to AC power signal output to Tx coil 118 from inverter 116). Rx coil 122 may output the transduced AC power signal to one or more components of WLC receiver 108, such as rectifier 124.

[0022] Rectifier 124 may be configured to convert an AC signal into a DC signal. For instance, rectifier 124 may convert an AC power signal received from Rx coil 122 into a DC power signal, and provide the DC power signal to another component of sink device 104, such as charger 110. In some examples, rectifier 124 may be an active full-bridge or half-bridge rectifier that includes a plurality of switches. In this sense, rectifier 124 may be considered to be an active rectifier (e.g., as opposed to a bridge formed entirely of passive diodes). Operation of the plurality of switches may be controlled by a controller. In other examples, rectifier 124 may be a passive rectifier.

[0023] In operation, Tx coil 118 and Rx coil 122 may be moved into proximity of each other. Power converter 116 may output an AC electrical signal to TX coil 118 that causesTX coil 118 to generate a magnetic field. RX coil 122 may transduce the magnetic field into an AC electrical signal and output said AC electrical signal to rectifier 124, which may convert the AC electrical signal into a DC electrical signal for output to other components of sink device 104. Components of sink device 104 may utilize the DC power signal output by WLC receiver 108 to perform various operations. For instance, charger 110 may utilize the DC power signal output by WLC receiver 108 to output a DC power signal, with a regulated current, to charge battery 112.

[0024] Operations of sink device 104, such as the charging of battery 112, may generate substantial heat. In general, higher charging currents may enable faster charging of battery 112, but may result in high heat generation levels. While faster charging of battery 112 may be desirable, it may not be desirable for an exterior of sink device 104 such as housing 126 to get too hot. As such, it may be desirable to enable faster charging of battery' 112 without housing 126 of sink device 104 getting too hot (e.g., staying within a certain thermal level).

[0025] In accordance with one or more aspects of this disclosure, charger 110 may adjust a charging current provided to battery' 112 based on an exterior temperature of sink device 104 (e.g., in order to keep sink device 104 within a predetermined thermal budget). For example, charger 110, based on determining that the temperature of the exterior of sink device 104 is increasing and approaching a maximum allowed temperature, may reduce the charging current provided to battery 112. Similarly, based on determining that the temperature of the exterior of sink device 104 is below the maximum allowed temperature, charger 110 may increase the charging current provided to battery' 112.

[0026] As noted above, charger 110 may selectively adjust (e.g., increase and decrease) the charging current provided to battery 112. In some examples, charger 110 may alternate between two charging currents. For instance, charger 110 may cause battery' 112 to charge with a low current (e.g., 500 mA) where the exterior surface temperature is higher than a certain temperature threshold, and cause battery' 112 to charge with a high current (e.g., 1000 mA) where the exterior surface temperature is lower than a certain temperature threshold. The fluctuation of the external surface temperature maycause the oscillation of the charging current. However, such oscillation between charging currents may not be desirable.

[0027] In accordance with one or more aspects of this disclosure, charger 110 may use relatively small step changes in charging current. For example, charger 110 may adjust a charging current provided to battery 112 by steps of less than 10% of the maximumcharging current of sink device 104 (e.g., less than 100mA where the maximum charging current is 1000mA). By using small step changes in the charging current, charger 110 may more precisely control the charging of battery 112. This more precise control may enable battery 112 to receive higher average charging current, which may reduce charging time of battery 112. In this way, charger 110 may maximize charging current within a predetermined thermal level.

[0028] In accordance with one or more aspects of this disclosure, charger 110 or WLC receiver 108 may pause charging while Tx coil 118 and Rx coil 122 are close to each other. For example, WLC receiver 108 may pause charging for a predetermined period of time. In another example, WLC receiver 108 may pause charging until housing 126 reaches a predetermined temperature. In yet another example, WLC receiver 108 may pause charging when the charging current has reached a predetermined minimum current threshold but the temperature of sink device 104 is higher than a certain threshold. By temporarily pausing charging, the temperature of sink device 104 may decrease rapidly, and may allow the surface temperature of the housing 126 to fall back to a desired level.

[0029] In accordance with one or more aspects of this disclosure, WLC receiver 108 maycause sink device 104 may display a GUI that indicates sink device 104 is still charging while charging is paused by WLC receiver 108 and Tx coil 118 and Rx coil 122 are close to each other. In an example, WLC receiver 108 causes sink device 104 to display a GUI that indicates that the sink device 104 is still charging while WLC receiver 108 has paused charging. By causing sink device 104 to display a GUI that indicates that sink device 104 is still charging while charging is paused, WLC receiver 108 may reduce the likelihood that a user mistakenly removes sink device 104 from source device 102 in the belief that charging is completed or terminated when charging is only paused.

[0030] While described herein with regards to wireless charging, sink device 104 may perform similar operations when charging battery' 112 using electrical energy received via a wire / cable. For instance, while receiving electrical energy via a universal serial bus type C (USB-C) cable, charger 110 may adjust a charging current of battery 112 based on an external surface temperature of sink device 104.

[0031] FIG. 2 is a block diagram illustrating sink device 204 with controller 236, in accordance with one or more aspects of this disclosure. Sink device 204 includes processors 206, WLC receiver 208, charger 210, battery 212, temp sensors 216, storage devices 218, communication units 228, and user interface devices 230.

[0032] Processors 206 may implement functionality and / or execute instructions within sink device 204. For example, processors 206 may receive and execute instructions that provide the functionality of application modules 240A-240N (“modules 240”), operating system 220 (“OS 220”), and charging manager 222. These instructions executed by processors 206 may cause sink device 204 to store and / or modify information within storage devices 218 during program execution. Processors 206 may execute instructions of modules 240, OS 220, and charging manager 222 to perform one or more operations. That is, modules 240, OS 220, and charging manager 222 may be operable by processors 206 to perform various functions described herein.

[0033] Sink device 204 includes temp sensors 216. Temp sensors 216 may include one or more temperature sensors located within a housing of sink device 204. In an example, temp sensors 216 includes one or more multiple temperature sensors located at multiple locations within a housing of sink device 204. In another example, temp sensors 216 include a temperature sensor located within the housing of sink device 204 near battery 212.

[0034] Temp sensors 216 may provide temperature data to controller 236. In an example, temp sensors 216 may provide temperature data that includes individual temperature readings from one or more of temp sensors 216 to controller 236. In another example, temp sensors 216 provide a temperature reading that is a composite of temperature readings from multiple temperature sensors within sink device 204. Sink device 204 may process the multiple readings to generate a composite that is a virtualized skin surface temperature of sink device 204 (e.g., a temperature that may represent a temperature of the skin of the device, but may not actually be a measured temperature of the skin). In this way, temp sensors 216 may provide temperature data that reflects the temperature of an outer surface of sink device 204. Temp sensors 216 may provide a temperature data of an outer surface of sink device 204 to enable a more accurate determination of the temperature of sink device 204 that is less impacted by the temperature of individual components of sink device 204 (e.g., reducing the impact that a single heat-generating component such as a rectifier has on temperature readings). Temp sensors 216 may record the temperature of the outer surface of sink device 204 while sink device 204 is charging.

[0035] WLC receiver 208 may be configured to wirelessly receive power from another device. WLC receiver 208 may be substantially similar to WLC receiver 108 as illustrated in FIG. 1. WLC receiver 208 may include rectifier 224.

[0036] Rectifier 224 may be configured to convert an AC signal into a DC signal. For instance, rectifier 224 may convert an AC power signal received by WLC receiver 208 into a DC power signal, and provide the DC power signal to another component of sink device 204, such as charger 210. In some examples, rectifier 224 may be an active fullbridge rectifier that includes a plurality of switches. In this sense, rectifier 224 may be considered to be an active rectifier (e.g., as opposed to a bridge formed entirely of passive diodes). Rectifier 224 may be substantially similar to rectifier 124 as illustrated in FIG. I. Rectifier 224 may include one or more components controlled by charger 210.

[0037] Sink device 204 includes charger 210. Charger 210 may manage a charging current provided to battery 212 via WLC receiver 208 and rectifier 224. Charger 210 may manage the charging current provided to battery 212 based on one or more data points such as the temperature of the exterior of sink device 204, state of charge (SOC) of battery 212, maximum power output of a wireless charger, and other data points. Charger 210 may be substantially similar to charger 110 as illustrated in FIG. 1.

[0038] Charger 210 includes controller 236. Controller 236 may be configured to assist charger 210 in controlling the charging current provided to battery 212 in accordance with one or more aspects of this disclosure. Controller 236 may include one or more types of controllers such as a feedback controller (e.g., a PID controller, P controller, PI controller, PD controller). Controller 236 may cause charger 210 to adjust the charging current of battery 212.

[0039] In accordance with one or more aspects of this disclosure, controller 236 may cause charger 210 to modify charging current received by battery 212 using one or more feedback controllers. For example, controller 236 may obtain data regarding the charging current of battery 212 and temperature data from temp sensors 216 and process the data to determine a charging current of battery 212. In an example, controller 236, responsive to determining that there is available thermal budget, may increase the charging current of battery 212. In another example, controller 236, responsive to determining that the temperature of sink device 204 is rapidly approaching a maximum allowable threshold, may reduce or pause the charging current of battery 212.

[0040] Controller 236 may use one or more types of feedback controllers such as PID controller to determine a charging current for battery 212. In an example, controller 236 provides data from temp sensors 216 and a current charging current to a PID controller. Controller 236 may use the output of the PID controller to determine the charging current of battery 212.

[0041] Controller 236 may use a feedback controller such as a PID controller to determine the charging current for battery 212 at specific time intervals. For example, controller 236 may cause a feedback controller to determine a charging current every' 30 seconds. Controller 236 may cause the feedback controller 236 to determine the charging current at specific time intervals to optimize the charging of battery 212 and quickly respond to changes in the temperahire of the exterior surface of sink device 204 (e.g., a drop in temperature that may allow for a higher charging current, an increase in temperature that may require that the charging current be reduced).

[0042] Controller 236 may clamp a minimum charging current. Controller 236 may clamp the minimum charging current to maintain a monotonic relationship between the exterior temperature of sink device 204 and a charging current of battery 212. In an example, controller 236, based on determining that the charging current has reached a minimum level, clamps the charging current to create a monotonic relationship between the charging current and the exterior temperature of sink device 204. Controller 236 may maintain the monotonic relationship between the exterior temperature and the charging current to aid in maximizing the charging current within a thermal budget.

[0043] Controller 236 may determine whether to temporarily pause charging of battery 212. Controller 236 may determine that one or more conditions have been met where pausing charging is more advantageous than reducing a charging current. For example, controller 236 may determine that while battery 212 is charging at a current substantially below a maximum charging current, the temperature of the exterior surface of sink device 204 is approaching or exceeds a certain temperature threshold. Controller 236 may temporarily pause charging to reduce the temperature of the exterior surface of sink device 204. In another example, controller 236 determines that the charging current of battery 212 has reached a minimum charging current, but that the exterior surface temperature of sink device 204 is approaching or exceeds a certain temperature threshold. Controller 236 may temporarily pause charging battery 212 until the exterior temperature of sink device 204 decreases to a predetermined threshold.

[0044] Controller 236 may cause sink device 204 to display a user interface that indicates that sink device 204 is charging while charging of battery' 212 is paused and sink device 204 is still located close to but disconnected from a source device. Controller 236, responsive to pausing charging of battery 212, may cause sink device 204 to generate a user interface (UI) that includes an indication that sink device 204 is still charging. For example, controller 236 may cause sink device 204 to generate a UI that includes a visualindication that sink device 204 is still charging (e.g., a visual element of battery with a lightning bolt, a blinking colored indicator, and other types of visual indicators). In another example, controller 236 may cause sink device 204 to play an auditory tone indicating that sink device 204 is still charging. Controller 236 may cause sink device 204 to display a UI that indicates that sink device 204 is still charging to discourage a user from removing sink device 204 from a source device. For example, controller 236 may cause sink device 204 to display a UI indicating that sink device 204 is still charging to prevent a user from mistakenly believing that charging is completed or terminated and removing sink device 204 from a source device.

[0045] FIG. 3 is a flowchart illustrating an example charging operation of an electronic in accordance with one or more aspects of this disclosure. In the example of FIG. 3, a feedback controller, such as PID controller 314, determines a charging current for sink device 304.

[0046] Sink device 304 may be a computing device such as a smartphone, smartwatch, laptop computer, tablet computer, or other type of computing device. Sink device 304 may be substantially similar to sink device 204 illustrated in FIG. 2. Sink device 304 may use PID controller 314 to determine a charging current for a batteiy of sink device 304 based on one or more data points such as a temperature of an exterior surface of sink device 304 and the weighted system load 368.

[0047] Sink device 304 may receive and process data from one or more temperature sensors located within sink device 304. For example, sink device 304 may receive data from temperature sensors located adjacent to a battery of sink device 304 in addition to a temperature sensor embedded within a housing, such as housing 326 of sink device 304. Sink device 304 may process the temperature data and determine an estimated temperature of the exterior surface of sink device 304. Sink device 304 may determine an exterior temperature that is a composite of temperatures from the one or more temperature sensors. Sink device 304 may further process the exterior surface temperature (“Virtual Skin Temp” as illustrated in FIG. 3).

[0048] Sink device 304 may process the exterior surface temperature along with data regarding previous exterior surface temperatures and determine an average exterior surface temperature as illustrated by temperature averaging 366. For example, sink device 304 may use data of exterior surface temperature over a 30 second period of time and determine an average surface temperature over the 30 second time period. Sink device304 may use a range of time periods from minutes to less than 30 milliseconds over which an average surface temperature is determined.

[0049] Sink device 304 may determine the difference between an averaged exterior surface temperature (e.g., from temperature averaging 366) and a target exterior surface temperature (e.g., target skin temp 360). Sink device 304 may determine the difference as part of a feedback loop that includes PID controller 314.

[0050] Sink device 304 may use the temperature difference data in PID controller 314.PID controller 314 may be a proportional-derivative-integral controller, or one or more of different types of feedback controllers. PID controller 314 may process data such as the temperature difference, weighted system load 368, predetermined offset 372, and determines an available thermal budget, the charging current of battery 312 that is delivered through charger 310 that is determined by thermal budget translator 370

[0051] PID controller 314 may include proportional control 350, integral control 352, and derivative control 356. PID controller 314 may use the difference of averaged exterior surface temperature (e.g., from temperature averaging 366) and target exterior surface temperature (e.g., target skin temp 360) for each of controls 350, 352, and 356. PID controller 314 may simultaneously perform controls 350, 352, and 356. Additionally, PID controller 314 may use a max / min clamp of thermal budget such as max / min value clamp 358 to limit the calculated value of integral control 352, and max / min value clamp 362 to limit the calculated value of PID controller 314.

[0052] PID controller 314 may combine the output of controls 350, 352, and 356. Weighted system load 368 and offset 372 in PID controller 314 may adjust the combined output of controls 350, 352, and 365. PID controller 314 may output the adjusted combined output of controls 350, 352, and 356 to another component such as thermal budget translator 370. Thermal budget translator 370 may process the adjusted output of controls 350, 352, and 356 to determine a charging current for one or more batteries of sink device 304.

[0053] PID controller 314 may use a thermal budget clamp such as max / min value clamp 362 to determine a charging current for one or more batteries such as battery 312 of sink device 304. For example, PID controller 314 may use a max'inin value clamp 362 to override a thermal budget determined by values of 350, 352, 356, 358, 368 and 372 that is higher than the value of the maximum allowed thermal budget. In another example, controls of components 350, 352, 356, 358, 368 and 372 determine a thermal budget that is lower than a minimum thermal budget value of max / min value clamp 362. PIDcontroller 314 sets the thermal budget to the value of the minimum allowed thermal budget.

[0054] Sink device 304 may apply output clamping after integral control 352 and before the output of PID controller 314. Sink device 304 may apply clamping of a minimum output current value based on one or more virtual-skin temperatures of housing 326. For example, sink device 304 may apply clamping with 1 -degree Celsius hysteresis.

[0055] Charger 310 sets the charging current for one or more batteries to the charging current determined by thermal budget translator 370. Charger 310 may determine the thermal budget and therefore charging current and cause the one or more batteries to charge at the charging current.

[0056] FIGS. 4A-4F are example graphs showing parameters of various charging techniques, in accordance with one or more aspects of this disclosure. FIG. 4A illustrates an example circuit of a charger and FIGS. 4B-4L illustrate example parameters of various charging techniques in the context of the circuit of FIG. 4A.

[0057] FIG. 4A illustrates an example circuit of a computing deGee, in accordance with the one or more techniques of this disclosure. In the example of FIG. 4A, power source 402 provides power to charging circuit 480. Power source 402 may be one or more types of power source such as a wireless power receiver, USB charger, or LIGHTNING charger, or other types of chargers. Power source 402 may provide power to charging circuit 480 for charging circuit 480 to charge battery 412 and power one or more components of a computing device. Power source 402 may be configured by charging circuit 480.

[0058] Charging circuit 480 may include one or more components that facilitate the charging of battery 412 and provide power to other components of a computing device. For example, charging circuit 480 may include one or more transistors, diodes, switches, and other components in addition to those illustrated. Charging circuit 480 may receive power at a charging voltage as indicated by “CHARGING VOLTAGE” with respect to ground as illustrated in FIG. 4A.

[0059] Charging circuit 480 may provide power to one or more components of a computing device that are represented by system load 482. System load 482 may include one or more components such as CPUs, GPUs, RAM, storage devices, input / output devices, communication devices, and other components. System load 482 may represent a resistive load, capacitive load, or inductive load generated by the one or more components of the computing device.

[0060] Charging circuit 480 may manage a charging current provided to battery 412 and system load 482. Charging circuit 480 may use one or more components to manage the flow of current from charging circuit 480 to battery 412 and system load 482. In the example of FIG. 4A, charging circuit 480 provides a current, labeled as “CHARGING CURRENT” to battery 412 and system load 482.

[0061] Charging circuit 480 may manage the charging current provided to battery 412 based on one or more factors. For example, charging circuit 480 may cease providing a charging current once battery 412 reaches a predetermined state of charge (illustrated as “BATTERY SOC”). In another example, charging circuit 480 may increase the charging current responsive to determining that there is available thermal budget. In yet another example, charging circuit 480 may decrease the charging current of battery 412 responsive to determining that system load 482 has increased.

[0062] FIGS. 4B-4F are example graphs showing parameters of various charging techniques, in accordance with one or more aspects of this disclosure. For the purposes of clarity, FIGS. 4B-4F are discussed in the context of FIG. 4 A.

[0063] FIG. 4B is an example graph showing parameters of various charging techniques in accordance with one or more aspects of this disclosure. In the example of FIG. 4B, charging circuit 480 manages the flow of current to battery 412 and system load 482 from power source 402 while maintaining the temperature of a housing that includes charging circuit 480, battery 412, and system load 482 below a specific thermal limit when the system load is stable. For example, charging circuit 480 may modify a charging current (“CHARGING CURRENT” as illustrated in FIG. 4A, “Charging Current” as illustrated in FIG. 4B) to keep the temperature of the housing (labeled as “Exterior Temp”) below 25°C+AT degrees Celsius.

[0064] FIG. 4C is an example graph showing parameters of various charging techniques in accordance with one or more aspects of this disclosure. In the example of FIG. 4C, charging circuit 480 adjusts a charging current to maintain the temperature of a housing (“Exterior Temp” as illustrated in FIG. 4C) below a specified temperature when the system load is fluctuating. Charging circuit 480 may cause battery 412 to charge with a charging current that is adjusted in step changes to maximize the charging current within a thermal budget as battery 412 charges.

[0065] Charging circuit 480 may adjust charging current with relatively small step changes to maximize use of a thermal budget. For example, as illustrated in FIG. 4C, charging circuit 480 may modify charging current by step sizes of less than 5% of themaximum allowed charging current. Charging circuit 480 may modify the charging current by step sizes of less than 5% of the maximum allowed charging current to keep Exterior Temp below a maximum temperature while not ceasing charging entirely (e.g., as illustrated by Exterior Temp oscillating within a temperature range in FIG. 4C).

[0066] Charging circuit 480 may use a feedback controller, such as controller 236 as illustrated in FIG. 2, to determine a charging current for battery' 412. Charging circuit 480 may provide data regarding the exterior surface temperature to controller 236. Controller 236 may process the data and determine a new thermal budget. Controller 236 may include a feedback controller such as a PID controller to determine the new thermal budget. Charging circuit 480 may cause battery 412 and system load 482 to charge at the new charging current based on the new thermal budget.

[0067] FIG. 4D is an example graph showing parameters of various charging techniques in accordance with one or more aspects of this disclosure. In the example of FIG. 4D charging circuit 480 adjusts a charging current (“CHARGING CURRENT” as illustrated in FIG. 4A, “Charging Current” as illustrated in FIG. 4D) to maintain the temperature of a housing (labeled as “Exterior Temp”), such as the exterior surface of the housing, below a specified temperature.

[0068] Charging circuit 480 may temporarily pause providing power to battery 412 and system load 482 to reduce the exterior surface temperature. For example, as illustrated in FIG. 4D, charging circuit 480 may temporarily set the charging current at 0 mA (e.g., sink device 304 requests the source device to stop generating magnetic fields) to reduce the exterior surface temperature. Responsive to determining that the exterior surface has dropped below a certain temperature, charging circuit 480 resumes providing power to battery 412 and system load 482.

[0069] A computing device that includes charging circuit 480, such as sink device 204 as illustrated by FIG. 2, may generate a GUI that indicates that sink device 204 is still charging while charging is paused. Sink device 204 may generate the GUI while charging circuit 480 pauses the charging of battery 412 to discourage a user from disconnecting sink device 204 from power source 402 while charging circuit 480 pauses charging. Responsive to an exterior surface temperature falling below a threshold and / or predetermined temperature, charging circuit 480 may resume causing battery 412 to charge with a charging current.

[0070] FIG. 4E is an example graph showing parameters of various charging techniques in accordance with one or more aspects of this disclosure. In the example of FIG. 4E,charging circuit 480 provides power to battery 412 and system load 482 through a charging current (“CHARGING CURRENT” as illustrated in FIG. 4A, “Charging Current” as illustrated in FIG. 4E) and adjusts the charging current based on the exterior surface temperature. In some examples, charging circuit 480 may adjust charging current with relatively large step changes in response to rapid temperature changes of the exterior surface. For example, charging circuit 480 briefly reduces the charging current with large steps due to a spike in the exterior surface temperature. Responsive to the exterior surface temperature falling back to the target temperature, charging circuit 480 increases the charging current to maximize charging current.

[0071] FIG. 4F is an example graph showing parameters of various charging techniques in accordance with one or more aspects of this disclosure. In the example of FIG. 4F, charging circuit 480 provides power to battery 412 and system load 482 through a charging current (“CHARGING CURRENT” as illustrated in FIG. 4A, “Charging Current” as illustrated in FIG. 4F).

[0072] Sink device 204 may determine the minimum charging current of the charging circuit 480 and ensure a monotonic relationship between the charging current and the exterior surface temperature of the housing. For example, as illustrated in FIG. 4F, charging circuit 480 provides power to battery 412 and system load 482 at different stepped currents ranging from 0 to maximum allowed charging current over time. In some examples, charging circuit 480 may provide power to battery 412 and system load 482 at a charging current that is stepped in value by 10% of the maximum charging current of the sink device. In another example, the sink device determines a minimum threshold of charging current when the exterior surface temperature reaches its lowest temperature value

[0073] FIG. 5 is a flowchart illustrating an example operation of a computing device in accordance with one or more aspects of this disclosure. For the purposes of clarity, FIG. 5 will be described with respect to FIG. 2.

[0074] A controller of a sink device, such as controller 236 of sink device 204, obtains a present temperature of an outer surface of sink device 204, such as a housing of sink device 204, while a battery of sink device 204, such as battery 212, is being charged (502). Sink device 204 may obtain the present temperature based on measurements performed by one or more temperature sensors such as temp sensors 216. Sink device 204 may obtain one or more present temperatures from temp sensors 216 and determine a composite temperature from the obtained one or more present temperatures.

[0075] Sink device 204 determines, based on the present temperature of the outer surface of sink device 204, a charging current for battery 212 (504). Sink device 204 may use controller 236 to determine the charging current for battery 212, where controller 236 includes a PID controller. In addition, sink device 204 may determine the charging current based on a system load of sink device 204.

[0076] Sink device 204 causes battery 212 to charge with the determined charging current (506). Sink device 204 may cause battery 212 to pause charging (e.g., sink device 204 sets the charging current to zero by requesting the source device to stop generating magnetic fields). Sink device 204 may cause battery 212 to charge with the determined charging current for a predetermined period of time before determining a second charging current.

[0077] The following numbered examples may illustrate one or more aspects of this disclosure:

[0078] Example 1: A method includes obtaining, by a controller of a computing device, a present temperature of an outer surface of the computing device while a battery of the computing device is being charged; determining, by the controller and based on the present temperature of the outer surface of the computing device and a target temperature of the outer surface of the computing device, a thermal budget and an associated charging current for the battery and system of the computing device; and causing, by the controller, the battery to charge with the determined charging current.

[0079] Example 2: The method of example 1, wherein the controller of the computing device is a proportional-integral-derivative controller, and wherein the proportional- integral-derivative controller determines a clamp for one of a maximum charging current for the battery and system or minimum charging current for the battery and system of the computing device.

[0080] Example 3: The method of any of examples 1 and 2, wherein causing the battery to charge further comprises causing the battery to charge via a power transmitter.

[0081] Example 4: The method of any of examples 1-3, further includes obtaining, by the controller, a plurality of temperatures over a period of time of the outer surface of the computing device while the battery of the computing device is being charged; determining, by the controller and based on the plurality of temperatures of the outer surface, that the temperature of the outer surface of the computing device has reached a predetermined thermal threshold while the battery is charging with at least a minimum charging current; determining, by the controller, whether the computing device isconnected to a power source or within a predetermined proximity of a power transmitter; and based on determining that the computing device is connected to the power source or is within the predetermined proximity of the power transmitter power transmitter, causing, by the controller, the battery to cease charging for a period of time.

[0082] Example 5: The method of example 4, further includes based on causing the battery to cease charging for a period of time, generating, by the computing device, a graphical user interface, wherein the graphical user interface indicates that the computing device is still charging; and outputting, for display and by the computing device, the graphical user interface.

[0083] Example 6: The method of any of examples 1-5, further includes clamping, by the controller, the determined minimum / maximum charge current.

[0084] Example 7: The method of example 6, further includes causing, by the controller, the battery to charge at a variable charging current, wherein the variable charging current is based on a monotonic relationship between the variable charging current and the present temperature of the outer surface of the computing device.

[0085] Example 8: The method of any of examples 1-7, wherein the present temperature is a moving average of a plurality of temperatures of the outer surface of the computing device.

[0086] Example 9: The method of any of examples 1-8, wherein the present temperature is a composite of a plurality of temperatures from one or more temperature sensors.

[0087] Example 10: The method of example 1, further includes obtaining, by the controller, a plurality of temperatures of the outer surface of the computing device while the battery of the computing device is being charged, and wherein determining the charging current comprises, determining a minimum charging current based on the plurality of temperatures; and causing the battery to charge with a charging current at least that of the minimum charging current.

[0088] Example 11 : A computing device includes a battery and one or more programmable processors configured to: obtain a present temperahire of an outer surface of the computing device while the battery of the computing device is being charged; determine, based on the present temperature of the outer surface of the computing device and a target temperahire of the outer surface of the computing device, a charging current for the battery and system of the computing device; and cause the battery to charge with the determined charging current.

[0089] Example 12: The computing device of example 11, wherein the one or more programmable processors determine, using a proportional-integral-derivative controller, a clamp for one of a maximum charging current or minimum charging current for the battery and system of the computing device.

[0090] Example 13: The computing device of example 11, wherein to cause the battery to charge further comprises to cause the battery to charge via a power transmitter.

[0091] Example 14: The computing device of example 11 , wherein the one or more processors are further configured to: obtain, by the controller, a plurality of temperatures over a period of time of the outer surface of the computing device while the battery' of the computing device is being charged; determine, by the controller and based on the plurality of temperatures of the outer surface, that the temperature of the outer surface of the computing device has reached a predetermined thermal threshold while the battery is charging with at least a minimum charging current; determine, by the controller, whether the computing device is connected to a power source or is within a predetermined proximity with a power transmitter; and based on determining that the computing device is connected to the power source or is within the predetermined proximity with a power transmitter, causing, by the controller, the battery to cease charging for a period of time.

[0092] Example 15: The computing device of example 14, wherein the one or more processors are further configured to: based on causing the battery to cease charging for a period of time, generating, by the computing device, a graphical user interface, wherein the graphical user interface indicates that the computing device is still charging; and output, for display and by the computing device, the graphical user interface.

[0093] Example 16: The computing device of example 11, wherein the one or more processors are further configured to: clamp, by the controller, the determined charging current at a minimum / maximum charge current.

[0094] Example 17: The computing device of example 16, wherein the one or more processors are further configured to: cause, by the controller, the battery' to charge at a variable charging current, wherein the variable charging current is based on a monotonic relationship between the variable charging current and the present temperature of the outer surface of the computing device.

[0095] Example 18: The computing device of example 11, wherein the present temperature is an average of a plurality of temperatures of the outer surface of the computing device.

[0096] Example 19: The computing device of example 11, wherein the present temperature is a composite of a plurality of temperatures from one or more temperature sensors,

[0097] Example 20: The computing device of example 11, wherein the one or more processors are further configured to: obtain, by the controller, a plurality of temperatures of the outer surface of the computing device while the battery of the computing device is being charged, and wherein to determine the charging current comprises, determine a minimum charging current based on the plurality of temperatures; and cause the battery to charge with a charging current at least that of the minimum charging current.

[0098] Example 21: A non- transitory computer-readable medium encoded with instructions that, when executed, cause one or more processors of a computing device to obtain a present temperature of an outer surface of the computing device while a battery of the computing device is being charged; determine, based on the present temperature of the outer surface of the computing device and a target temperature of the outer surface of the computing device, a charging current for the battery and system of the computing device; and cause the battery to charge with the determined charging current.

[0099] Example 22: The non-transitory computer-readable medium of example 21, wherein the instructions further cause the one or more processors to determine, using a proportional-integral-derivative controller, a clamp for one of a maximum charging current or minimum charging current for the battery' and system of the computing device.

[0100] Example 23: The non-transitory computer-readable medium of example 21 , wherein the instructions further cause the one or more processors to cause the battery to charge via a power transmitter.

[0101] Example 24: The non-transitory computer-readable medium of example 21, wherein the instructions further cause the one or more processors to: obtain a plurality of temperatures over a period of time of the outer surface of the computing device while the battery of the computing device is being charged; determine, based on the plurality of temperatures of the outer surface, that the temperature of the outer surface of the computing device has reached a predetermined thermal threshold while the battery is charging with at least a minimum charging current; determine whether the computing device is connected to a power source or is within a predetermined proximity with a power transmitter; and based on determining that the computing device is connected to the power source or is within the predetermined proximity with a power transmitter, cause the battery to cease charging for a period of time.

[0102] Example 25: The non-transitory computer-readable medium of example 24, wherein instructions further cause the one or more processors to; based on causing the battery to cease charging for a period of time, generate a graphical user interface, wherein the graphical user interface indicates that the computing device is still charging; and output, for display, the graphical user interface.

[0103] Example 26; The non-transitory computer-readable medium of example 21 , wherein the instructions are further configured to cause the one or more processors to clamp the determined charging current at a minimum / maximum charge current.

[0104] Example 27; The non-transitory computer-readable medium of example 26, wherein the instructions are further configured to cause the one or more processors to: cause the battery to charge at a variable charging current, wherein the variable charging current is based on a monotonic relationship between the variable charging current and the present temperature of the outer surface of the computing device.

[0105] Example 28; The non-transitory computer-readable medium of example 21 , wherein the present temperature is a moving average of a plurality of temperatures of the outer surface of the computing device.

[0106] Example 29: The non-transitory computer-readable medium of example 21 , wherein the present temperature is a composite of a plurality of temperatures from one or more temperature sensors.

[0107] Example 30; The non-transitory computer-readable medium of example 21, wherein the instructions are further configured to cause the one or more processors to: obtain a plurality of temperatures of the outer surface of the computing device while the battery of the computing device is being charged; and wherein determine the charging current comprises determine a minimum / maximum charging current based on the plurality of temperatures; and cause the battery to charge with a charging current at least that of the minimum charging current. Various aspects have been described in this disclosure. These and other aspects are within the scope of the following claims.

Claims

CLAIMS:

1. A method comprising: obtaining, by a controller of a computing device, a present temperature of an outer surface of the computing device while a battery of the computing device is being charged; determining, by the controller and based on the present temperature of the outer surface of the computing device and a target temperature of the outer surface of the computing device, a charging current for the battery and system of the computing device; and causing, by the controller, the battery' to charge with the determined charging current.

2. The method of claim 1, wherein the controller of the computing device is a proportional-integral-derivative controller, and wherein the proportional-integral- derivative controller determines a clamp for one of a maximum charging current or minimum charging current for the battery and system of the computing device.

3. The method of any of claims 1 and 2, wherein causing the battery to charge further comprises causing the battery to charge via a power transmitter.

4. The method of any of claims 1-3, further comprising: obtaining, by the controller, a plurality of temperatures over a period of time of the outer surface of the computing device while the battery of the computing device is being charged; determining, by the controller and based on the plurality of temperatures of the outer surface, that the temperature of the outer surface of the computing device has reached a predetermined thermal threshold while the battery is charging with at least a minimum charging current; determining, by the controller, whether the computing device is connected to a power source or is within a predetermined proximity with a power transmitter; and based on determining that the computing device is connected to the power source or is within the predetermined proximity with a power transmitter, causing, by the controller, the battery to cease charging for a period of time.

5. The method of claim 4, further comprising: based on causing the battery to cease charging for a period of time, generating, by the computing device, a graphical user interface, wherein the graphical user interface indicates that the computing device is still charging; and outputting, for display and by the computing device, the graphical user interface.

6. The method of any of claims 1-5, further comprising: clamping, by the controller, the determined charging current at a minimum / maximum charge current.

7. The method of claim 6, further comprising: causing, by the controller, the battery to charge at a variable charging current, wherein the variable charging current is based on a monotonic relationship between the variable charging current and the present temperature of the outer surface of the computing device.

8. The method of any of claims 1-7, wherein the present temperahire is an average of a plurality of temperatures of the outer surface of the computing device.

9. The method of any of claims 1-8, wherein the present temperature is a composite of a plurality of temperatures from one or more temperahire sensors.

10. The method of any of claims 1 -9, further comprising: obtaining, by the controller, a plurality of temperahires of the outer surface of the computing device while the battery of the computing device is being charged, and wherein determining the charging current comprises determining a minimum or maximum charging current based on the plurality of temperahires; and causing the battery to charge with a charging current at least that of the minimum charging current and at most that of the maximum charging current.i 1 . A computing device, comprising a battery; and one or more programmable processors, and configured to: obtain a present temperature of an outer surface of the computing device while the battery of the computing device is being charged; determine, based on the present temperature of the outer surface of the computing device and a target temperature of the outer surface of the computing device, a charging current for the battery and system of the computing device; and cause the battery to charge with the determined charging current.

12. The computing device of claim 11 , wherein the one or more programmable processors determine, using a proportional-integral-derivative controller, a clamp for one of a maximum charging current or minimum charging current for the battery and system of the computing device.

13. The computing device of any of claims 11-12, wherein the one or more programmable processors are further configured to: obtain a plurality of temperatures over a period of time of the outer surface of the computing device while the battery of the computing device is being charged; determine, based on the plurality of temperatures of the outer surface, that the temperature of the outer surface of the computing device has reached a predetermined thermal threshold while the battery is charging with at least a minimum charging current; determine whether the computing device is connected to a power source or is within a predetermined proximity with a power transmitter; and based on determining that the computing device is connected to the power source or is within the predetermined proximity with a power transmitter, causes the battery to cease charging for a period of time.

14. The computing device of claim 13, wherein the one or more programmable processors are further configured to: based on causing the battery to cease charging for a period of time, generate a graphical user interface, wherein the graphical user interface indicates that the computing device is still charging; and output, for display, the graphical user interface.

15. A non-transitory computer-readable medium, encoded with instructions that, when executed, cause one or more processors of a computing device to perform any of the methods of claims 1-10.

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