Fan Air Volume Control Using Torque and Speed Feedback
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Solution Overview
Problem
Existing air-conditioning fan systems face challenges in maintaining constant air volume due to varying static pressures, which requires costly and complex microprocessor control units to measure and adjust torque, increasing costs and risk of failure.
Innovation Solution
A method that establishes a functional relation formula Q=F (T, n, V) to calculate air volume by testing torque and rotational speed relationships, using a microprocessor control unit to adjust torque based on target air volume, allowing the motor to operate at constant torque states and adjusting coefficients through table look-up methods to achieve accurate air volume control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an air volume meter is installed to maintain constant air volume, then air volume control accuracy is improved, but system cost and failure risk increase
Solution Approach 1:
The patent extracts the air volume measurement function from a dedicated air volume meter and integrates it into the existing motor control system. By using the motor's rotational speed sensor and torque data to calculate air volume through the formula Q=F(T, n, V), the system eliminates the need for separate air volume meters, thereby reducing cost and failure risk while maintaining control accuracy
Solution Approach 2:
The motor control system is given multiple functions: it not only controls motor speed but also measures air volume by utilizing existing sensors (rotational speed sensor) and calculations based on torque and speed relationships. This multi-functional approach eliminates the need for dedicated air volume measurement devices
2Measurement precision
If a powerful microprocessor control unit is used to measure static pressure and calculate torque for speed adjustment, then air volume control accuracy is improved, but system cost increases
Solution Approach 1:
Instead of directly measuring static pressure with complex sensors and powerful microprocessors, the patent creates a computational model that copies the air volume measurement function using existing motor control data. The functional relation formula Q=F(T, n, V) allows the system to calculate air volume from torque and rotational speed, which are already measured by the motor control system's existing sensors
Solution Approach 2:
The patent replaces the mechanical/static pressure measurement approach with a computational/mathematical approach. By establishing the functional relationship between torque, rotational speed, and air volume, the system substitutes complex pressure sensing and calculation with simpler rotational speed measurement and mathematical modeling
3Adaptability or versatility
If the system adapts to a wide range of static pressures, then adaptability is improved, but control complexity increases
Solution Approach 1:
The patent achieves adaptability to wide static pressure ranges by making the control system adjustable through parameter changes. The functional relation formula Q=F(T, n, V) includes an adjustment coefficient V that can be modified to accommodate different static pressure conditions. The system allows users to input different target air volumes and adjusts torque accordingly, providing flexibility without requiring complex hardware changes
Data Source
AI summary
A method for controlling air volume including: inputting a target air volume into the microprocessor control unit of the motor controller; starting a motor by the motor controller under a torque to enable the motor to work in a steady state; recording the rotational speed in the steady state, and establishing a functional relation formula Q=F (T, n, V) to calculate an air volume in the steady state; comparing the target air volume with the calculated air volume; re-recording a steady rotational speed after the motor falls on a new steady state under an increased or reduced torque, and recalculating the air volume in the new steady state; and repeatedly adjusting the torque until the calculated air volume is equal or equivalent to the target air volume.