Server Fan Control With a Delay Circuit for Voltage-Drop Stalling
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Solution Overview
Problem
In server systems, when alternating current voltage drops, it leads to insufficient power supply to fans, causing a reduction in fan speed, which triggers overcurrent protection switches, resulting in fan stalling and potential overheating of critical components.
Innovation Solution
A fan control system utilizing a delay circuit and energy storage unit to prevent overcurrent protection switch triggering, ensuring fan operation resumes after voltage recovery, maintaining heat dissipation efficiency and preventing component damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the fan controller performs closed-loop control to increase PWM duty cycle when voltage drops, then fan rotating speed is maintained, but surge current increases and triggers overcurrent protection switch
Solution Approach 1:
The delay circuit performs preliminary action by delaying the closing signal to the overcurrent protection switch when voltage drops are detected. This prevents the switch from closing during voltage fluctuations, avoiding surge current and overcurrent protection triggering, while allowing the fan controller to maintain fan speed through closed-loop control.
2Reliability
If the overcurrent protection switch is triggered to protect the fan, then fan stalling is prevented, but heat dissipation capability is lost and critical components may overheat
Solution Approach 1:
The delay circuit performs preliminary action by anticipating voltage drops and delaying the overcurrent protection switch closing signal. This prevents unnecessary fan stalling while maintaining protection capability, ensuring continuous heat dissipation and preventing critical component overheating.
3Reliability
If the mainboard immediately responds to voltage drop by stopping fan operation, then power supply safety is ensured, but heat dissipation continuity is compromised
Solution Approach 1:
The delay circuit performs preliminary action by delaying the response to voltage drops. When voltage drops are detected, the delay circuit postpones the stopping signal to the overcurrent protection switch, allowing the fan to continue operating temporarily and maintaining heat dissipation continuity while power supply safety is still ensured.
Data Source
AI summary
A fan control system, a server system, and a fan control method and apparatus. The fan control system includes a measurement circuit and a delay circuit, the measurement circuit acquiring a first voltage of an alternating current power supply and/or a second voltage output by a power supply unit during rotating of a fan; when the first voltage and/or the second voltage drops, a mainboard stops outputting a closing signal to the delay circuit, whereby an energy storage unit discharges within a preset time, the delay circuit being provided between an output end of the mainboard and an enabling end of an overcurrent protection switch, and the delay time of the delay circuit being the preset time. The mainboard is used for outputting, when the server system satisfies a preset cooling condition, the closing signal to the overcurrent protection switch by means of the delay circuit.