Fan Brake Circuit for Fast Stop Without Airflow Blockage
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Solution Overview
Problem
Conventional fan brake mechanisms fail to effectively brake fans that are power-off, leading to continued rotation due to inertia, which can block airflow and disrupt cooling functions, especially in dual-rotor or serial fans.
Innovation Solution
A fan brake circuit comprising a control module, motor driving module, and brake control module, which includes an energy storage unit and brake unit to quickly brake the fan by forming a short-circuit loop when power is off, allowing the fan to rotate via windmill effect and maintain cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional fan brake mechanism is used to brake the fan when power is off, then the fan rotation is suppressed, but the cooling function is blocked due to airflow resistance
Solution Approach 1:
The brake control module operates periodically rather than continuously - it activates the brake unit only during specific periods (when power is first off and fan inertia is high) and then deactivates it. This periodic operation allows the fan to be braked when necessary while maintaining airflow continuity for cooling during other periods
Solution Approach 2:
The brake control module dynamically adjusts the braking state based on real-time conditions. It monitors the power supply state and controls the brake unit to switch between braking and non-braking states, making the system adaptive rather than static. This dynamic control ensures optimal balance between stopping rotation and maintaining cooling
2Speed
If the brake unit continuously brakes the failed fan, then the fan rotation speed is suppressed, but airflow is blocked and cooling effect is lost
Solution Approach 1:
The brake control module applies preliminary braking action only when needed (when power is off and windmill effect would cause problematic rotation), and then removes the braking action. This preliminary and conditional anti-action prevents the harmful effect of continuous braking while still achieving the initial goal of controlling rotation speed
Solution Approach 2:
The brake control module extracts the brake unit from the main power circuit and controls it independently through a separate control circuit. This separation allows the brake unit to be selectively activated only when needed, rather than being continuously engaged, thus preventing airflow blockage while maintaining cooling functionality
3Reliability
If discrete transistor/capacitor brake circuit is used, then brake function is achieved, but device complexity increases and is not suitable for dual-rotor or serial fans
Solution Approach 1:
The brake control module merges the brake control functionality with the existing motor control structure. The brake unit shares the same control module and power circuits as the motor, eliminating the need for separate discrete transistor/capacitor brake circuits. This integration reduces device complexity while maintaining reliable brake function for dual-rotor and serial fan configurations
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
Enables quick fan braking without continuous resistance, ensuring airflow continuity and maintaining cooling functionality even when one fan fails.
Implementation Method 1
the motor forms a short-circuit loop and is braked
Implementation Method 2
allowing the fan to rotate via windmill effect and maintain cooling
Data Source
AI summary
A fan brake circuit includes a control module, a motor driving module electrically connected to the control module and a motor, and a brake control module including an energy storage unit, a stored energy supply control unit electrically connected to the energy storage unit and an input power supply, and a brake unit electrically connected to the stored energy supply control unit and the motor. When the fan is power off, the stored energy supply control unit controls the energy storage unit to output an operating voltage to the brake unit, which then transmits a brake signal to the motor for braking the fan quickly (or immediately) at the time of power off. The brake action ends once the fan stopped, but the fan is still rotatable by airflows produced by another fan as a result of windmill effect to keep providing a certain degree of cooling effect.