Outdoor Fan Rotor Pre-Positioning for Counter-Wind Startup
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Solution Overview
Problem
Conventional startup methods for outdoor fans with high-speed rotating rotors against the wind face significant challenges, including low success rates and instability, especially when the external wind is strong.
Innovation Solution
A method for pre-positioning the rotor of an outdoor fan by sending signals to the inverter circuit to achieve a short-circuit brake, measuring phase currents, calculating back electromotive forces, and determining the position angle of the rotor to apply resistance torque and stop the rotor before starting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the outdoor fan starts directly when the rotor rotates at high speed against the wind, then the startup process can begin immediately, but the startup success rate becomes very low and the system becomes unstable
Solution Approach 1:
The patent applies preliminary action by performing rotor position detection and pre-positioning operations before the actual startup. The system detects the rotor position during high-speed counter-rotation and pre-positions the rotor to an optimal starting angle, ensuring that when startup commences, the motor is already in the correct state for successful operation, thus resolving the contradiction between immediate startup and startup success rate
Solution Approach 2:
The patent applies preliminary anti-action by counteracting the adverse effects of high-speed counter-rotation before startup. The system detects and compensates for the rotor position caused by high-speed rotation against the wind, pre-positioning the rotor to overcome the unfavorable starting conditions, thereby improving startup reliability without delaying the startup process
2Reliability
If the system waits for external wind to decrease before startup, then the rotor speed decreases to low speed and startup success rate improves, but the startup time increases and user convenience decreases
Solution Approach 1:
The patent applies parameter changes by transforming the rotor position parameters detected during high-speed counter-rotation into a pre-positioned angle suitable for startup. The system calculates the rotor position based on back electromotive force during high-speed rotation and converts this information into a predetermined starting position, enabling successful startup without waiting for wind conditions to change, thus eliminating the time loss while maintaining high startup success rate
Solution Approach 2:
The patent performs preliminary rotor position detection and calculation during the high-speed counter-rotation state, before startup is initiated. By detecting the rotor position and calculating the appropriate starting angle in advance, the system prepares all necessary parameters during the waiting period, so that when startup begins, no additional time is needed for position detection or adjustment, effectively eliminating the time loss associated with waiting for wind to decrease
3Speed
If the rotor rotates at high speed against the wind, then the fan can respond quickly to wind changes, but the startup stability deteriorates and startup failure occurs frequently
Solution Approach 1:
The patent applies feedback by continuously monitoring the rotor position during high-speed counter-rotation and using this information to determine the optimal startup moment. The system detects the back electromotive force, calculates the rotor position, and uses this feedback to pre-position the rotor and initiate startup at the most favorable moment, thereby maintaining startup stability even when the rotor is rotating at high speed against the wind
Solution Approach 2:
The patent applies dynamics by adapting the startup strategy based on the real-time rotational state of the rotor. Instead of using a fixed startup procedure, the system dynamically adjusts the startup parameters based on the detected rotor position and speed, enabling successful startup whether the rotor is stationary, rotating with the wind, or rotating against the wind at high speed, thus maintaining startup stability across all dynamic conditions
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 method allows for rapid stopping of the rotor during high-speed counter-wind rotation, improving the success rate of starting the permanent-magnet synchronous motor without waiting for external wind forces to decrease, ensuring stable and reliable operation.
Implementation Method 1
sending a signal to the inverter circuit to turn off all the upper electronic switching tubes and turn on all the lower electronic switching tubes, thereby achieving a short-circuit brake
Implementation Method 2
measuring a phase current of each phase coil winding in the stator assembly; calculating a back electromotive force of each phase coil winding in the stator based on the phase current
Data Source
AI summary
A method for pre-positioning a rotor of an outdoor fan in a counter-rotation state before operation includes: 1) during a counter-operation state, sending, by a microprocessor, a signal to the inverter circuit to turn off all upper electronic switching tubes and turn on all lower electronic switching tubes; 2) measuring a phase current of each phase coil winding in the stator assembly; 3) calculating a back electromotive force of each phase coil winding in the stator; 4) calculating a position angle of the rotor assembly; 5) checking if the phase current of each phase coil winding is all smaller than a preset threshold current; if not, return to 1); if yes, proceed to 6); and 6) calculating a resistance torque to stop the rotor assembly based on the position angle of the rotor assembly, and then stopping the rotor assembly to achieve pre-positioning of the rotor before starting.