Fan Synchronization via Feedback Control to Eliminate Beating Noise
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Solution Overview
Problem
Existing fan systems in large-scale communication devices experience noise issues due to fluctuations in fan rotation rates caused by variations in smoothing circuit characteristics, leading to beating sounds, which are difficult to control effectively with existing PWM control methods.
Innovation Solution
The implementation of a fan system with a pulse signal generation portion and rotation rate control circuit that uses reference and actual rotation pulse signals to achieve synchronized fan rotation rates through FLL or PLL control, ensuring all fans operate in harmony and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PWM control is used to control fan rotation rates, then fan rotation can be adjusted according to temperature, but fluctuation in smoothing circuit characteristics causes rotation rate instability and beating noise
Solution Approach 1:
The patent implements feedback control by detecting the actual rotation rate of each fan and comparing it with the target rotation rate. The control apparatus adjusts the PWM duty cycle based on the detected rotation rate to maintain stable and synchronized fan operation, eliminating the beating noise caused by characteristic variations in smoothing circuits.
2Stability of the object's composition
If rotation rates of multiple fans are controlled to be the same, then fans should operate in harmony, but characteristic variations in smoothing circuits cause different fluctuations and produce beating sounds
Solution Approach 1:
The control apparatus detects the rotation rate of each fan individually and provides feedback control to adjust the PWM signal. This ensures that all fans maintain the same rotation rate despite variations in smoothing circuit characteristics, preventing the generation of beating noise and achieving harmonious operation.
3Stability of the object's composition
If constant rotation rates are maintained for all fans, then operational harmony is achieved, but any slight variation in rotation rates still produces beating noise
Solution Approach 1:
The system continuously monitors the rotation rate of each fan and adjusts the PWM duty cycle in real-time to maintain precise synchronization. This feedback mechanism ensures that even slight variations in rotation rates are corrected, preventing beating noise while maintaining operational harmony.
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 reduces unusual sounds like beat noise by ensuring all fans rotate at the same rate, even with slight variations, thereby improving operational harmony and noise reduction.
Implementation Method 1
a rotation detection portion arranged to detect a rotation of the motor portion
Implementation Method 2
a drive circuit arranged to drive the motor portion; an impeller arranged to be rotated by the motor portion
Data Source
AI summary
A fan system includes a pulse signal generation portion and a plurality of fans. Each of the plurality of fans preferably includes a motor portion; an impeller arranged to be rotated by the motor portion; a drive circuit arranged to drive the motor portion; a rotation detection portion arranged to detect rotation of the motor portion; and a rotation rate control circuit arranged to, based on a reference pulse signal supplied from the pulse signal generation portion and an actual rotation pulse signal supplied from the rotation detection portion, exercise feedback control on a rotation rate of the motor portion in accordance with a period of the reference pulse signal.