Patent Application
20180026451
Embodiments of the invention relate to thermal management of a system that processes a workload while charging its battery.
Modern portable devices are typically equipped with a rechargeable battery that can be repeatedly drained and charged over a lifespan of several years. A rechargeable battery is typically connected to a charger, which converts input voltage and current to a level compatible with the battery. An intelligent charger may optimize the charging process by initially charging the battery at the maximum rate until a preset temperature is reached, then slowing down or stopping the charge so as not to exceed the temperature limit. By monitoring the temperature and regulating the charging process, permanent damage to the battery can be avoided.
One main contributor to the rise in temperature during the charging process is the charger's inefficiency. A typical charger is not 100% efficient, which means that a portion of its input power is converted into heat instead of being stored in the battery. Some advanced chargers are provided with fast charging capabilities. A fast charger draws in an increased amount of power (e.g., at an increased level of input voltage and/or current) than a regular charger during the charging process. The increased input power causes an increased heat output, which further heightens the need for thermal management.
Modern portable devices, such as laptops, tablets, smartphones, and other consumer electronics, are designed to run system and user space applications while their batteries are being charged. Concurrent charging and application executions can rapidly raise the device temperature and negatively impact the performance of the applications.
Thus, there is a need for improvement in thermal management for rechargeable devices to allow for concurrent workload execution and fast charging.
In one embodiment, a method of thermal management is provided for a mobile device. The method comprises: determining a thermal headroom, which is an amount of power in a form of heat that heat dissipation hardware in the mobile device is estimated to dissipate when the mobile device operates at a target temperature; determining a first power allocation to system loading caused by one or more applications running on the mobile device; subtracting the first power allocation from the thermal headroom to obtain a second power allocation to a charger that charges a battery module of the mobile device while the one or more application are running; and setting an input power limit of the charger based on the second power allocation.
In another embodiment, a mobile device is provided to perform thermal management. The mobile device comprises a memory; one or more processors coupled to the memory; and a charger for charging a battery module of the mobile device. The one or more processors are operative to: determine a thermal headroom, which is an amount of power in a form of heat that heat dissipation hardware in the mobile device is estimated to dissipate when the mobile device operates at a target temperature; determine a first power allocation to system loading caused by one or more applications running on the mobile device; subtract the first power allocation from the thermal headroom to obtain a second power allocation to the charger while the one or more application are running; and set an input power limit of the charger based on the second power allocation.
The embodiments of the invention enable a system, such as a mobile device, to concurrently charge its battery and execute system workload without negative performance impact on the workload. Advantages of the embodiments will be explained in detail in the following descriptions.
The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that different references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
In the following description, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure the understanding of this description. It will be appreciated, however, by one skilled in the art, that the invention may be practiced without such specific details. Those of ordinary skill in the art, with the included descriptions, will be able to implement appropriate functionality without undue experimentation.
Embodiments of the invention provide a system and method for thermal management of a system that is concurrently charging its battery and executing its workload. The system includes a thermal manager, which controls the allocation of power to the charger and system loading with minimized system performance impact. The thermal manager optimally utilizes the thermal headroom provided by the system hardware, and may dynamically adjust the thermal headroom when the system temperature cannot be maintained at a target temperature. The target temperature is a temperature at which the system hardware can operate safely, as excessive temperature can degrade the performance, life, and reliability of the system.
The thermal headroom, as used herein, is the amount of power in the form of heat that heat dissipation hardware in the system is estimated to dissipate when the system operates at a target temperature. The amount of thermal headroom that a system has may be calibrated and estimated by a hardware manufacturer, and provided to system designers as a default value with an error margin. The thermal headroom may be specified by the hardware manufacturer as a given power value; e.g., N watts. In one embodiment, the system may allocate a portion of the N watts to the power loss of the charger caused by charging inefficiency, and another portion of the N watts to workload execution. In one embodiment, the workload execution has a higher priority in the allocation of the N watts over the charging inefficiency. Prioritizing workload execution optimizes system performance during the charging process.
However, during system operation, there are various factors that may cause the system temperature to deviate from the target temperature; for example, the environment in which the system operates, whether the heat generating components in the system are spaced apart or concentrated in one area, etc. If the heat dissipation hardware does not bring the system to the target temperature, the thermal headroom may be adjusted based on the amount of temperature deviation from the target temperature. An operating temperature higher than the target temperature may damage the system hardware, and an operating temperature lower than the target temperature means that more power may be allocated to the system; e.g., more power may be allocated to the power loss of the charger, thereby allowing the charging speed to increase.
In one embodiment, the system 100 further includes a memory 140, such as a combination of volatile memory and non-volatile memory, and one or more processors 160, such as central processing units (CPUs), graphics processing units (GPUs), and/or other types of special-purpose and general-purpose processors. The system 100 also includes a display 185 and/or other I/O units 180; e.g., a touch screen, a keyboard, a home button, a touch pad, etc. Non-limiting examples of the system 100 may include smartphone, laptop, smartwatch, or other portable or wearable devices.
In one embodiment, the system 100 includes a power distributor 190 to distribute power to the functional components (e.g., processors 160, memory 140, display 185, I/O units 180, etc.) of the system 100. The power distributor 190 may receive power through the adapter 130 from a power outlet, and distribute power to the functional components for their operations. When the system 100 is not plugged into a power outlet, the power distributor 190 receives power from the battery 110 (e.g., via a path 105). The charger 120 and the power distributor 190 may concurrently receive power from the adapter 130 when the system 100 is plugged into a power outlet; for example, when the battery 110 is charging and the functional components are also executing a workload. In one embodiment, the thermal manager 150 determines the amount of power supplied to the charger 120 to charge the battery 110 and the amount of power supplied to the functional components for executing the workload.
In one embodiment, the charger 120 is not 100% efficient when it charges the battery 110. That is, when the charger 120 sends power to the battery 110 to store electric charges in the battery cells, a portion of the power is lost (e.g., to chemical reactions) in the form of heat. The term “charging inefficiency” refers to the percentage of lost power by the charger 120 over its received power when charging the battery 110. In one embodiment, the charging inefficiency stays substantially the same (e.g., 10%) for a range of power levels received at the input of the charger 120. That is, if the charger 120 receives 10 watts of input power, 1 watt of power is lost in the form of heat due to charging inefficiency. Thus, the higher the input power level is, the more heat is generated due to the charging inefficiency.
In addition to the charging inefficiency, the system 100 also generates heat due to system loading; i.e., the workload executed by its functional components. The system 100 is designed to safely operate at or below a target temperature. To maintain the temperature at or below this target temperature, the system 100 includes heat dissipation hardware 155 (e.g., cooling fans, heat pipes, etc.) for dissipating a predetermined amount of heat over a given time period. Thermal headroom is the amount of power in the form of heat that heat dissipation hardware 155 is estimated to dissipate when the system 100 operates at the target temperature. To ensure safe operation of the system 100, the power allocation of the system 100, including system loading and power loss from charging inefficiency, is kept within the system's thermal headroom.
The system 100 further includes a number of sensor 170, such as temperature sensors to monitor the temperature within the system, the printed circuit board (PCB) or the system-on-a-chip (SoC) on which the system 100 is located, and the like. The measured system temperature can be used to adjust the thermal headroom, the system power allocation, and/or the power input to the charger 120.
In one embodiment, the system 100 provides a fast charging mode, which draws a higher amount of current (e.g., higher than a threshold) into the charger 120 than a regular charging mode. The input voltage to the charger 120 may be fixed, variable, or tiered across the different charging modes. The faster charging time is enabled by a higher amount of power that the charger 120 receives at its input. However, more power is lost due to charging inefficiency in the fast charging mode than in the regular charging mode.
The system 100 may execute a system workload when charging the battery 110. This system workload is also referred to as system loading. For example, the system 100 may execute a gaming application, display a video, or perform other power-consuming operations in the system space or the user space.
In one embodiment, given the thermal headroom 210 (e.g., provided by a hardware manufacturer) and an estimation of the system loading 220, the charger power loss 230 can be calculated by subtracting the system loading 220 from the thermal headroom 210. Since the charging inefficiency is known (e.g., provided by a hardware manufacturer), the amount of power input to the charger 110 can be calculated by dividing the charger power loss 230 by the charging inefficiency.
In one embodiment, the sensors 170 also include temperature sensors 340, which monitor the temperature in the system 100 to ensure safe operation of the system 100. The output of the temperature sensors 340 may be relied on for adjusting the thermal headroom 210, as will be described in more detail with reference to
The process 400 begins with the thermal manager 150 receiving system status information at step 410. The system status information includes temperature information. Using the temperature information, the thermal manager 150 determines whether to adjust the thermal headroom at step 420. Detailed operations of step 420 are described in connection with
The process 500 begins with the thermal manager 150 receiving system temperature data (“SysTemp”) at step 510; e.g., from the temperature sensors 340 of
More specifically, if SysTemp is greater than the target temperature by TH, the thermal headroom is decreased at step 530. A higher-than-target temperature means that the power allocated to the heat generating components in the system 100 is more than the capacity of the heat dissipating hardware. In some cases if the temperature issue is not resolved in time, the system temperature may keep increasing and cause permanent damage to the system hardware.
If SysTemp is less than the target temperature by TH, the thermal headroom is increased at step 540. In some cases SysTemp may stay at a stable temperature below the target temperature, or in some other cases SysTemp may continue to decrease below the target temperature. That is, the system temperature does not reach the target temperature during concurrent workload execution and battery charging. A lower-than-target temperature means that the power allocated to the heat generating components in the system 100 is less than the capacity of the heat dissipating hardware, and it also means that more power may be allocated to the heating generating components. Since the system loading is given priority over the charger power loss in power allocation, the increased thermal headroom may be provided to the charger such that the charger is allowed to draw in more power and charge at a faster rate. The process 500 proceeds from step 530 or step 540 to step 430 of
In one embodiment, the method 600 may be performed by a processing system, such as the system 100 of
The operations of the flow diagrams of
Various functional components or blocks have been described herein. As will be appreciated by persons skilled in the art, the functional blocks will preferably be implemented through circuits (either dedicated circuits, or general purpose circuits, which operate under the control of one or more processors and coded instructions), which will typically comprise transistors that are configured in such a way as to control the operation of the circuitry in accordance with the functions and operations described herein.
While the invention has been described in terms of several embodiments, those skilled in the art will recognize that the invention is not limited to the embodiments described, and can be practiced with modification and alteration within the spirit and scope of the appended claims. The description is thus to be regarded as illustrative instead of limiting.
This application claims the benefit of U.S. Provisional Application No. 62/364,903 filed on Jul. 21, 2016, the entirety of which is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 62364903 | Jul 2016 | US |
