Dual PID Controller for Thermal Management in Portable Computing Devices
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Solution Overview
Problem
Portable computing devices face thermal management challenges due to the lack of active cooling, leading to performance degradation through throttling, and battery current limitations that can cause voltage drops and device failures.
Innovation Solution
A dual proportional integral derivative (PID) loop controller system that monitors temperature and adjusts operating parameters such as frequency, transmission power, and data rates to mitigate thermal issues while minimizing performance impact, using on-chip and off-chip thermal sensors to maintain optimal device operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If thermal mitigation algorithms throttle components to reduce heat generation, then temperature control is improved, but device performance deteriorates
Solution Approach 1:
The patent implements dynamic thermal mitigation by using a dual PID loop controller that continuously adjusts operating parameters (frequency, transmit power, data rate) based on real-time temperature feedback. Instead of static throttling, the system dynamically optimizes the balance between temperature control and performance by adapting parameters to current thermal conditions, thereby reducing performance degradation while maintaining effective cooling.
Solution Approach 2:
The system employs feedback mechanisms through temperature sensors (TSENS) that provide real-time temperature data to the thermal mitigation algorithm. The dual PID controller uses this feedback to continuously adjust operating parameters, creating a closed-loop control system that optimizes both temperature management and performance by responding to actual thermal conditions rather than using fixed throttling rules.
2Productivity
If components draw high current to maintain performance, then device performance is improved, but voltage drop increases causing device failure
Solution Approach 1:
The patent applies preliminary action by proactively monitoring current draw and predicting potential voltage drop conditions before they cause device failure. The dual PID controller anticipates high-current scenarios and pre-adjusts operating parameters to prevent voltage drops, rather than reacting after the problem occurs. This predictive approach maintains performance while preventing reliability issues.
Solution Approach 2:
The system uses feedback from voltage and current monitoring to continuously adjust operating parameters. When voltage drops are detected or predicted, the system responds by adjusting frequency, transmit power, or data rate to reduce current demand, thereby maintaining reliability while minimizing performance impact through real-time adaptive control.
3Speed
If operating frequency is increased to improve performance, then processing speed is improved, but thermal generation increases
Solution Approach 1:
The patent implements dynamic frequency scaling through the dual PID controller that continuously adjusts operating frequency based on real-time temperature feedback. Instead of static high-frequency operation, the system dynamically optimizes frequency to achieve maximum processing speed within thermal constraints, thereby improving both speed and temperature management through adaptive control.
Data Source
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AI summary
A temperature of a component within the portable computing device (PCD) may be monitored along with a parameter associated with the temperature. The parameter associated with temperature may be an operating frequency, transmission power, or a data flow rate. It is determined if the temperature has exceeded a threshold value. If the temperature has exceeded the threshold value, then the temperature is compared with a temperature set point and a first error value is then calculated based on the comparison. Next, a first optimum value of the parameter is determined based on the first error value. If the temperature is below or equal to the threshold value, then a present value of the parameter is compared with a desired threshold for the parameter and a second error value is calculated based on the comparison. A second optimum value of the parameter may be determined based on the second error value.