Pump Motor Speed Control Using Variable Gain Thresholds
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Solution Overview
Problem
Existing pump systems face challenges in rapidly and accurately adjusting motor speed in response to changes in load, leading to potential over-speed conditions and inefficiencies in returning to target speed after load reduction.
Innovation Solution
A pump controller that adjusts the current applied to the motor based on a gain setting, switching between different gain values based on the difference between actual and target motor speeds, with higher gain values applied when the deviation exceeds specific thresholds to increase sensitivity and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a fixed gain value is used in the speed control system, then the control logic is simple, but the system cannot rapidly and accurately adjust motor speed in response to load changes
Solution Approach 1:
The patent applies dynamics by making the gain value adjustable based on operating conditions. The controller switches between a first gain value and a second gain value depending on whether the motor speed deviation exceeds a threshold, allowing the system to adapt its responsiveness to actual load changes rather than using a fixed gain setting.
Solution Approach 2:
The patent changes the control parameter (gain value) based on the magnitude of speed deviation. When the deviation exceeds the threshold, the controller uses a second gain value that is higher than the first gain value, enabling faster correction of large deviations while maintaining stability for small deviations.
2Measurement precision
If a high gain value is always applied, then the system is highly sensitive to speed deviations, but it causes oscillations and instability when the deviation is small
Solution Approach 1:
The patent applies local quality by using different gain values for different operating conditions. The controller selectively applies a first gain value when the speed deviation is within the threshold and a second (higher) gain value when the deviation exceeds the threshold, providing appropriate control sensitivity for each local operating state.
Solution Approach 2:
The control system dynamically adjusts the gain value based on the current speed deviation magnitude. This dynamic adjustment allows the system to be highly sensitive to small deviations (using the first gain value) while remaining stable during large deviations (switching to the second gain value), preventing both oscillation and excessive responsiveness.
3Adaptability or versatility
If the system uses a single threshold for gain switching, then the control logic is simple, but it cannot handle varying degrees of speed deviation effectively
Solution Approach 1:
The patent implements parameter changes by switching between two distinct gain values based on whether the speed deviation exceeds a threshold. This allows the system to adapt its control characteristics to match the severity of the deviation, providing effective response for both small and large load changes without requiring complex multi-level thresholds.
Data Source
AI summary
Systems and methods of controlling the speed of a pump configured to move liquid through a pump system are described. The actual motor speed of the pump motor is controlled by adjusting a current applied to the motor based on the difference between the actual motor speed and the target motor speed according to a gain setting. A first gain value is applied as the gain setting when the difference between the actual motor speed and the target motor speed does not exceed a first threshold. However, a second, higher gain value is applied when the difference between the actual motor speed and the target motor speed exceeds the first threshold.