Motor Air Volume Control Without Static Pressure Measurement
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Solution Overview
Problem
Existing methods for controlling air volume in household air-conditioners face challenges such as high cost, low accuracy, and the need for complex calculations due to varying static pressures, especially when dust deposition or filter blockages occur, leading to inconsistent air volume delivery.
Innovation Solution
A method that determines low and high torque intervals for a motor, establishing functional relation formulas to calculate air volume based on torque and rotational speed, allowing for adaptive control without real-time static pressure measurement, using a microprocessor to adjust torque and achieve target air volume with high accuracy and low computational requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an air volume meter is installed to achieve constant air volume control, then air volume control accuracy is improved, but system cost and reliability are worsened due to increased components and potential meter failure
Solution Approach 1:
The patent extracts the air volume measurement function from a dedicated air volume meter and integrates it into the existing static pressure sensor measurement system. By using the static pressure sensor to infer air volume through established relationships rather than direct measurement, the system eliminates the need for additional air volume meter components while maintaining control accuracy.
Solution Approach 2:
The patent introduces a mathematical model as an intermediary between static pressure measurement and air volume control. The model Q = k1 * n + k2 * n^2 / P establishes the relationship between static pressure (P), rotational speed (n), and air volume (Q), allowing the system to calculate air volume indirectly through the mediator model rather than requiring direct measurement.
2Measurement precision
If logarithmic computation or high-order polynomials are used to calculate air volume from static pressure, then air volume control accuracy is improved, but device complexity and manufacturing cost are worsened due to stronger MCU requirements
Solution Approach 1:
The patent changes the mathematical parameters from complex logarithmic or high-order polynomial computations to a simplified linear and quadratic model Q = k1 * n + k2 * n^2 / P. This parameter transformation maintains sufficient calculation accuracy for air volume control while dramatically reducing the computational burden on the MCU, allowing implementation on low-cost, low-power microcontrollers.
3Device complexity
If a single mathematical model is used for air volume calculation across all torque ranges, then device complexity is reduced, but manufacturing precision is worsened due to inability to correct individual air volume accuracy at specific operating positions
Solution Approach 1:
The patent segments the torque range into multiple intervals (low torque interval 0-Tm and high torque interval Tm-T0) and establishes different functional relation formulas for each interval. This segmentation allows the system to optimize the mathematical model for specific operating conditions, improving air volume calculation accuracy at different torque levels while maintaining manageable system complexity through modular formula selection.
Data Source
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AI summary
A method for controlling air volume output by a motor. The method includes: 1) establishing functional relation formulas for air volume in a low torque interval and a high torque interval; 2) inputting a target air volume into a microprocessor control unit; 3) starting a motor under a torque to enable the motor to reach a steady state; 4) acquiring an adjustment coefficient under the torque, and calculating the air volume; 5) comparing the target air volume with the calculated air volume; 6) re-recording a steady rotational speed after the motor reaches a new steady state under an increased or reduced torque, and recalculating the air volume in the new steady state; and 7) repeating steps 5) and 6) to adjust the torque until the calculated air volume is equal or equivalent to the target air volume.