Air Blower Motor Torque Control for Stable Airflow Convergence
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Solution Overview
Problem
Conventional motor control techniques for air blowers in air-conditioning systems face instability in achieving constant air flow rates due to varying pressure loss conditions, requiring optimal gain settings that can be excessive and lead to slow convergence of air flow rates to target values.
Innovation Solution
A motor control device that calculates and adjusts the torque command by multiplying the motor torque by the square of the ratio of the target air flow rate to the current air flow rate, ensuring rapid and stable convergence to the target air flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional motor control techniques with gain adjustment are used, then the air flow rate can be controlled to follow the target air flow rate, but the convergence becomes slow and unstable operation occurs
Solution Approach 1:
The invention changes the control parameter from linear gain multiplication to square of gain multiplication. Specifically, the torque command is calculated by multiplying the square of the gain by the ratio of target air flow rate to current air flow rate, rather than using linear gain adjustment. This nonlinear parameter transformation enables both rapid convergence and operational stability simultaneously
Solution Approach 2:
The invention introduces dynamic adaptation of the control gain based on the ratio between target and current air flow rates. The gain is not fixed but dynamically adjusted as the square of the flow rate ratio, allowing the system to automatically adapt its control strength according to the deviation from target, achieving both fast response and stability
2Loss of time
If the gain is increased to speed up convergence, then the air flow rate reaches target faster, but unstable operation occurs
Solution Approach 1:
The invention transforms the linear gain parameter into a squared gain parameter. By calculating the torque command as the square of the gain multiplied by the air flow rate ratio, the system achieves accelerated convergence without the instability caused by linear gain increases. This parameter transformation fundamentally changes the control characteristics to simultaneously reduce convergence time and maintain reliability
3Adaptability or versatility
If pressure loss conditions vary in the air-conditioning system, then the air flow rate deviates from target value, but conventional control cannot maintain constant air flow rate
Solution Approach 1:
The invention implements feedback control by continuously monitoring the current air flow rate and comparing it with the target air flow rate. The torque command is dynamically adjusted based on the ratio of target to current air flow rate, creating a closed-loop control system that automatically compensates for pressure loss variations and maintains precise air flow rate control
Solution Approach 2:
The invention uses nonlinear parameter transformation by squaring the gain factor in the torque command calculation. This transformation enhances the system's adaptability to pressure loss changes while maintaining control precision, as the squared gain provides more aggressive correction for larger deviations while still achieving stable convergence
Data Source
AI summary
A motor control device according to the present invention is a device for controlling a motor driving an air blower. The motor control device includes: an air flow rate calculator configured to calculate an air flow rate supplied by the air blower; and a torque command generator configured to multiply a motor torque by a square of a ratio of a target air flow rate to the air flow rate or multiply a previously outputted torque command by the square of the ratio of the target air flow rate to the air flow rate, and generate a result of the multiplication as a torque command.