Constant Air Volume Control Using Interpolation Without Flowmeter
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Solution Overview
Problem
Existing methods for controlling constant air volume in electric devices, such as air conditioners and blower systems, are costly due to the need for air flowmeters and complex motor controllers, and complicate installation, affecting ventilation efficiency.
Innovation Solution
A method that integrates constant air volume control functions on a system controller's main control circuit board, eliminating the motor controller from the motor body, using a microprocessor, inverter circuit, and operation parameter detecting circuit to regulate motor parameters and rotational speed through interpolation and curve fitting, ensuring constant air suction or output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an air flowmeter is directly installed in an air duct to ensure constant volume air flow, then air volume control accuracy is improved, but production cost increases and device complexity increases
Solution Approach 1:
The patent extracts the air flowmeter from the motor body and relocates it to the air duct, separating the measurement function from the motor control system. This allows the motor controller to be simplified while maintaining air volume measurement capability through the relocated flowmeter and pressure sensor arrangement.
Solution Approach 2:
The main control circuit board is designed to perform multiple functions: motor control, air volume measurement, and constant volume regulation. By integrating these functions into a single control system, the patent eliminates the need for a separate motor controller, reducing device complexity while maintaining control accuracy.
2Measurement precision
If a motor controller is installed on the motor body with complex computing capacity to achieve constant air volume control, then control accuracy is improved, but production cost increases and device complexity increases
Solution Approach 1:
The patent merges the motor controller functions with the main control circuit board, combining motor control and air volume regulation into a single integrated system. This eliminates the need for a separate high-computing-capacity motor controller, reducing production costs while maintaining control accuracy through the unified control algorithm.
Solution Approach 2:
The control algorithm transitions from requiring real-time complex computing to using pre-calculated lookup tables with interpolation. By changing the computational approach from dynamic calculation to table-based retrieval with linear interpolation, the patent reduces the required computing capacity while maintaining sufficient control accuracy.
3Speed
If the motor controller is installed on the motor body, then control response is improved, but installation complexity increases and ventilation efficiency is affected
Solution Approach 1:
The patent extracts the motor controller from the motor body, separating the control functions from the motor assembly. This simplifies motor installation in the air duct while the control functions are handled by the existing main control circuit board, reducing installation complexity without significantly impacting control response.
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 approach simplifies the product structure, reduces production costs, and maintains accurate air volume control without requiring powerful computing capacity, ensuring efficient ventilation and cost savings.
Implementation Method 1
A motor drives the wind wheel to rotate under the driving of the main control circuit board
Implementation Method 2
An operation parameter detecting circuit inputs real-time operation parameters into the microprocessor
Data Source
AI summary
A method for controlling air volume of an electric device to be constant, the device being adapted to exhaust or supply air, the method including: A) establishing M constant air volume control functions Qi=F(n) corresponding to M air volume points CFMi in the microprocessor of the system controller; B) allowing the microprocessor to receive or preset a target air volume IN-CFM; C) starting the motor, when the motor operates in a stable state, comparing M air volume points CFMi with the target air volume IN-CFM, and ensuring that the target air volume IN-CFM falls within two known air volume points CFMi and CFMi−1; D) using the two known air volume points CFMi and CFMi−1 to calculate a constant air volume control function Q0=F(n) corresponding to the target air volume IN-CFM by interpolation method; and E) controlling a motor parameter Q0 and a rotational speed n.