Powder Feeder Control for Faster Discharge Flow Stabilization
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Solution Overview
Problem
Conventional powdery-material feeding devices take a long time to stabilize the discharge flow rate of powdery materials after operation start, often resulting in inefficiencies and inaccuracies in supply.
Innovation Solution
The powdery-material feeding device employs a controller that alternates between constantly keeping-control and feedback-control to quickly stabilize the discharge flow rate. Initially, it conducts constantly keeping-control after startup or hopper filling, then shifts to feedback-control when the discharge flow rate difference from the target is within a threshold, and reverts to constantly keeping-control if the difference exceeds the threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If feedback-control is used to adjust the manipulated variable at predetermined cycles to reduce the difference between discharge flow rate and target value, then the discharge flow rate can be corrected, but it takes a long time to stabilize the discharge flow rate after operation start
Solution Approach 1:
The controller performs preliminary tuning by determining an estimated value of the discharge flow rate when the motor rotates at maximum speed before operation start. This preliminary action establishes a baseline that accelerates the subsequent stabilization process, reducing the time required to reach target discharge flow rate precision.
Solution Approach 2:
The controller dynamically switches between constantly keeping-control and feedback-control modes based on the absolute value of the difference between discharge flow rate and target value. This dynamic control strategy allows the system to quickly respond to large deviations while maintaining precision when close to the target, thereby reducing overall stabilization time.
2Stability of the object's composition
If constantly keeping-control is used immediately after motor start, then the manipulated variable remains stable, but the discharge flow rate cannot be corrected when the difference from target value is large
Solution Approach 1:
The controller dynamically transitions between constantly keeping-control and feedback-control modes based on real-time monitoring of the discharge flow rate difference from target value. When the absolute difference exceeds a predetermined threshold, the controller switches to feedback-control to correct the discharge flow rate, thereby maintaining both stability and accuracy.
Solution Approach 2:
The controller repetitively obtains the difference between discharge flow rate and target value, and when this difference exceeds the threshold, it adjusts the manipulated variable through feedback-control. This feedback mechanism ensures that discharge flow rate accuracy is maintained while allowing stability during periods when the system is already within acceptable parameters.
Data Source
AI summary
A powdery-material feeding device includes a controller configured to selectively conduct constantly keeping-control of constantly keeping rotational speed of a motor, current or voltage applied to the motor without any change as a manipulated variable for a predetermined period, or feedback-control of repetitively obtaining a difference between a discharge flow rate of the powdery material and a target value thereof at predetermined cycles and adjusting by increasing or decreasing the manipulated variable at each of the predetermined cycles in order to reduce the difference, the controller conducts the constantly keeping-control immediately after a motor starts, shifts to the feedback-control when the difference between the discharge flow rate of the powdery material and the target value thereof has an absolute value less than a threshold after the period for the constantly keeping-control elapses, and conducts constantly keeping-control without shifting to the feedback-control when the absolute value of the difference between the discharge flow rate of the powdery material and the target value thereof is more than the threshold after the period for the constantly keeping-control elapses, and the manipulated variable during the repeated constantly keeping-control is changed in accordance with the difference between the discharge flow rate of the powdery material and the target value thereof after elapse of the period for latest constantly keeping-control.