Fan Control Nonlinear Function Generation via Lookup Table
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Solution Overview
Problem
Existing fan control systems using PWMs face increased noise when duty cycle changes, and previous solutions like linear algorithms or piecewise linear equations are computationally intensive and hardware-expensive.
Innovation Solution
A system and method that converts a linear fan control function to a nonlinear function using a lookup table and bit manipulation to generate PWM or RPM values, reducing noise and computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If linear algorithms are used to control PWM duty cycle changes, then the control is simple, but fan noise increases when duty cycle changes
Solution Approach 1:
The patent transforms the linear duty cycle control parameter into a nonlinear parameter using a lookup table. The lookup table maps linear temperature values to nonlinear duty cycle values, enabling smoother transitions that reduce fan noise while maintaining simple control logic. This parameter transformation allows the system to achieve nonlinear control characteristics without complex computational algorithms.
2Object-generated harmful factors
If piecewise linear equations are used to control fan speed, then fan noise is reduced, but computational complexity and hardware cost increase
Solution Approach 1:
The patent uses a lookup table that stores pre-computed nonlinear duty cycle values corresponding to linear temperature inputs. Instead of performing complex piecewise linear calculations in real-time, the system copies pre-stored values from the lookup table based on the current temperature, achieving smooth nonlinear control with minimal computational overhead and simple hardware implementation.
3Speed
If PWM duty cycle is changed to control fan speed, then fan speed control is achieved, but fan noise increases
Solution Approach 1:
The patent applies a nonlinear transformation to the PWM duty cycle parameter through a lookup table. The lookup table contains pre-calculated duty cycle values that create smoother transitions between speed levels, reducing the abrupt changes that cause fan noise while maintaining effective speed control across the full operating range.
Data Source
AI summary
System and method for controlling a fan. A value may be received for controlling the fan. The value may include a first number of bits and may correspond to a linear function of temperature. A first value may be determined using a first number of bits of the value. A modification to the first value may be determined based on a second number of bits of the value. A new output value may be generated based on the first value and the modification to the first value. The new output value may correspond to a first nonlinear function of temperature. The new output value may be provided for controlling the fan.