Diode-Based PWM Signal Selection for Fan Speed Control
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Solution Overview
Problem
Conventional fan speed control systems in computing systems with multiple processing units are either costly due to the need for multi-channel fan controller ICs or inefficient as they lack the ability to selectively control fan speed for the processing unit dissipating the highest level of heat when using DC voltage controlled fans.
Innovation Solution
A system that includes sensors to generate pulse-width modulation signals for each processing unit, direct current voltage converters to convert these signals, and diodes on transmission lines to determine which voltage passes through, allowing the fan to be driven by the amplified voltage from the processing unit with the highest temperature, thereby controlling its speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a multi-channel fan controller IC and a fan capable of interpreting PWM signal directly are used, then the fan speed control precision is improved, but the system cost increases
Solution Approach 1:
The patent replaces expensive multi-channel fan controller ICs with inexpensive discrete components (diodes, resistors, capacitors) that can be easily obtained and implemented. The solution uses basic electronic components that are widely available and cost-effective, eliminating the need for specialized expensive controller ICs while achieving the same functional goal of selecting the highest temperature signal to control fan speed.
Solution Approach 2:
The patent divides the temperature monitoring and fan control function into separate discrete components for each processing unit. Each processing unit has its own temperature sensor and PWM signal generation, and the selection of the highest temperature signal is achieved through individual diode connections rather than a centralized multi-channel controller. This segmentation allows for simpler, cheaper implementation while maintaining the ability to control fan speed based on the hottest processing unit.
2Reliability
If the fan operates at full speed all the time, then the cooling reliability is improved, but the power consumption increases and fan life is shortened
Solution Approach 1:
The patent implements dynamic fan speed control by using PWM signals that vary in duty cycle based on the temperature of the processing units. Instead of operating at fixed full speed, the fan speed is dynamically adjusted according to real-time temperature conditions. The PWM duty cycle is modulated to provide just enough cooling power, reducing unnecessary power consumption and fan wear while maintaining adequate cooling reliability.
Solution Approach 2:
The system uses temperature sensors to continuously monitor the temperature of each processing unit and feeds this information back to the fan control circuitry. The feedback loop ensures that the fan speed is automatically adjusted based on actual thermal conditions, providing sufficient cooling when needed and reducing speed when temperatures are lower, thereby optimizing power consumption and fan life while maintaining cooling reliability.
3Device complexity
If a DC voltage controlled fan is used instead of PWM controlled fan, then the system cost is reduced, but the ability to control fan speed for specific processing units is lost
Solution Approach 1:
The patent introduces diodes as intermediary components that allow multiple PWM signal sources (from different processing units) to be selectively connected to a single DC voltage controlled fan. The diodes act as one-way valves that prevent signal interference while allowing the highest temperature signal to pass through and control the fan speed. This intermediary approach enables a simple DC controlled fan to achieve adaptive speed control based on multiple temperature sources.
Solution Approach 2:
The patent merges multiple PWM signal paths from different processing units into a single control path for the DC voltage controlled fan. By using diode-based signal combining, the system integrates temperature information from multiple sources into one unified control signal that drives the fan. This merging allows a single fan to respond to the thermal conditions of multiple processing units without requiring a complex multi-channel controller.
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 solution effectively and efficiently controls fan speed based on the highest temperature processing unit, reducing noise and power consumption while extending fan lifespan, suitable for systems with multiple processing units.
Implementation Method 1
a first diode coupled to the first direct current voltage converter, wherein the first diode determines whether the first direct current voltage passes through the first diode
Data Source
AI summary
A system for controlling the fan speed is described. Specifically, one embodiment of the present invention set forth a computing system, which includes a first processing unit including a first sensor, wherein the first processing unit is configured to generate a first pulse-width modulation signal, and a first transmission line further including a first direct current voltage converter configured to convert the first pulse-width modulation signal to a first direct current voltage and a first diode coupled to the first direct current voltage converter, wherein the first diode determines whether the first direct current voltage passes through the first diode. The computing system further includes an amplifier coupled to the first diode, wherein the amplifier is configured to amplify a selected direct current voltage to drive a fan.