Motor Air Volume Control Using Torque-Segmented Formulas
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Solution Overview
Problem
Existing methods for controlling air volume in household air-conditioners face challenges such as high costs, potential failures due to the need for air volume meters, and poor control accuracy, especially under varying static pressure conditions, which complicates the mathematical models and increases the computational requirements for motor controllers.
Innovation Solution
A method that determines low and high torque intervals for a motor, establishes functional relation formulas to calculate air volume based on torque and rotational speed, and uses a microprocessor control unit to adjust torque until the target air volume is achieved, with the ability to adapt to wide static pressure ranges and correct for individual air volume inaccuracies.
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 deteriorate 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-based control system. By using the static pressure sensor to infer air volume through mathematical models, the system eliminates the need for a separate air volume meter, thereby maintaining measurement capability while improving reliability and reducing cost.
Solution Approach 2:
The patent introduces mathematical models (first-order or second-order functions) as intermediaries that translate static pressure measurements into air volume calculations. These models act as a mediator between the static pressure sensor and the control system, enabling accurate air volume control without direct measurement, thus avoiding the reliability issues associated with additional sensing components.
2Measurement precision
If logarithmic computation or high-order polynomials are used to determine air volume from static pressure, then air volume calculation accuracy is improved, but device complexity and cost increase due to stronger MCU requirements
Solution Approach 1:
The patent changes the mathematical parameters from complex logarithmic or high-order polynomial functions to simpler first-order or second-order functions. This parameter simplification maintains adequate air volume calculation accuracy while significantly reducing the computational burden on the MCU, thereby lowering device complexity and cost without sacrificing essential control performance.
3Device complexity
If first-order or second-order functions are used to simplify the mathematical model, then device complexity and cost are reduced, but manufacturing precision deteriorates due to poor control accuracy in certain operating positions
Solution Approach 1:
The patent segments the torque range into multiple intervals (low torque interval and high torque interval), each with its own first-order or second-order function. This segmentation allows the system to use simpler mathematics overall while maintaining high precision at specific operating points by selecting the appropriate function for the current torque range, thus resolving the contradiction between simplicity and precision.
Solution Approach 2:
The patent applies different mathematical functions (first-order or second-order) to different torque intervals based on local requirements. Each interval has optimized parameters tailored to its specific operating characteristics, ensuring high control accuracy at each operating position while maintaining overall system simplicity. This local optimization approach prevents the need for overly complex global models.
4Device complexity
If a single mathematical model is used for the entire torque range, then device complexity is reduced, but adaptability deteriorates because the model cannot accurately represent different operating conditions
Solution Approach 1:
The patent implements a dynamic selection mechanism that automatically chooses the appropriate mathematical function (first-order or second-order) and parameters based on the current operating torque interval. This dynamic adaptation allows the system to maintain simplicity in structure while achieving high adaptability across the full range of static pressure conditions, as the model automatically adjusts to match current operating characteristics.
Data Source
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.