Thermal Management Using Digital Filter and Lookup Table
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Solution Overview
Problem
Portable handheld wireless communications devices face challenges in managing thermal behavior due to high heat generation from components like RF power amplifiers, leading to battery and external case temperature increases, which can reduce battery life and user comfort, and existing thermal management techniques are not sufficient to address these issues effectively.
Innovation Solution
A thermal management process that uses multiple temperature sensors and digital filters to estimate real temperature behavior at target locations within the device, applying thermal time constants and mathematical relationships to adjust power consumption of components such as the RF transceiver, CPU, and display backlight, thereby controlling temperature without significantly impacting user experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If power consumption of components is increased to improve performance, then device functionality and speed are improved, but temperature of battery and external case increases
Solution Approach 1:
The system performs preliminary thermal characterization during manufacturing to establish look-up tables that map temperature sensor readings to target location temperatures. This pre-computed data enables real-time thermal management without adding complex runtime computation, allowing the device to proactively adjust power consumption before excessive heating occurs.
Solution Approach 2:
The system implements continuous feedback by monitoring temperature at remote sensor locations and using this information to dynamically adjust the power consumption of heat-generating components. The feedback loop processes temperature readings, consults look-up tables to estimate target location temperatures, and automatically modifies component power levels to maintain safe operating temperatures.
2Measurement precision
If temperature sensors are placed at target locations to directly monitor temperature, then temperature measurement precision is improved, but device complexity increases due to additional sensors and space requirements
Solution Approach 1:
The system uses remote temperature sensors as intermediaries to indirectly monitor temperatures at target locations. By placing sensors at accessible remote locations and using look-up tables to correlate these readings with target location temperatures, the system achieves accurate thermal monitoring without requiring direct sensor placement at difficult-to-access hot spots.
Solution Approach 2:
The system creates a thermal model copy of the device's thermal behavior through pre-characterization data. The look-up tables represent a simplified copy of the complex thermal relationships between various components and locations, enabling accurate temperature estimation without physically replicating sensors at every critical point.
3Temperature
If power consumption actions are applied to reduce temperature, then thermal management effectiveness is improved, but device performance and user experience deteriorate
Solution Approach 1:
The system applies partial power consumption reductions only when and where needed, rather than uniformly throttling all components. By targeting specific heat-generating components based on actual thermal conditions and using graduated power reduction levels from the look-up tables, the system achieves effective temperature control while minimizing impact on overall device performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively manages thermal behavior by reducing heat generation, extending battery life, and maintaining user comfort by dynamically adjusting power consumption based on real-time temperature readings and correlations, ensuring temperatures remain within safe limits.
Implementation Method 1
A thermal management process uses multiple temperature sensors and digital filters to estimate real temperature behavior at target locations within the device, applying thermal time constants and mathematical relationships
Data Source
Figure 1
Figure 2A
Figure 2B~2C
AI summary
A thermal manager has a digital filter whose input is to receive raw temperature values from a sensor and whose output is to provide processed or filtered temperature values according to a filter function that correlates temperature at the sensor with temperature at another location in the device. The thermal manager has a look-up table that further correlates temperature at the sensor with temperature at said another location. The look-up table contains a list of processed temperature sensor values, and/or a list of temperatures representing the temperature at said another location, and their respective power consumption change commands. The thermal manager accesses the look-up table using selected, filtered temperature values, to identify their respective power consumption change commands. The latter are then evaluated and may be applied, to mitigate a thermal at said another location. Other embodiments are also described and claimed.