Variable-Speed Pump Control for Pressure-Stable Displacement Changes
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Solution Overview
Problem
Variable-speed variable displacement pumps face challenges in maintaining constant pressure and volume flow due to inadequate speed dynamics, leading to potential drops in pressure when adjusting displacement volume per working cycle, requiring frequent controller intervention.
Innovation Solution
Implementing a pilot control that adjusts the speed setpoint and torque setpoint using model predictive control, taking into account parameters like maximum and minimum displacement volume, pressure, and drive speed, to pre-control the speed and torque adjustments, ensuring constant variables without needing higher-level controller intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the displacement volume per operating cycle is adjusted, then energy efficiency is improved, but pressure stability deteriorates due to insufficient speed dynamics
Solution Approach 1:
The control device adjusts the speed setpoint before the displacement volume adjustment is completed, anticipating the upcoming change in hydraulic torque. This preliminary speed adjustment ensures that the drive is already optimized to handle the changing load conditions, preventing pressure drops and maintaining system stability throughout the transition.
Solution Approach 2:
The system dynamically adjusts both the displacement volume and speed setpoint based on real-time operating conditions. The control device continuously monitors the actual displacement volume and相应地 adjusts the speed setpoint, creating a dynamic control strategy that adapts to changing system requirements and maintains optimal performance.
2Adaptability or versatility
If the speed adjustment is delayed, then displacement volume can be adjusted, but pressure drops occur due to slow speed response
Solution Approach 1:
The control device proactively adjusts the speed setpoint based on the current displacement volume and anticipated changes, rather than waiting for pressure drops to occur. This forward-looking approach ensures speed response is synchronized with displacement adjustments, preventing pressure instability.
Solution Approach 2:
The control device uses feedback from the actual displacement volume and system conditions to continuously optimize the speed setpoint. This closed-loop control ensures that speed adjustments are timely and appropriate, maintaining pressure stability while enabling full displacement adjustment capability.
3Stability of the object's composition
If higher-level controller intervention is used, then pressure can be maintained, but system complexity increases
Solution Approach 1:
The control device autonomously manages speed adjustments based on displacement volume changes without requiring external intervention. The system self-regulates by continuously monitoring its own state and making appropriate speed setpoint modifications, eliminating the need for higher-level controllers and reducing overall system complexity.
Solution Approach 2:
The control device performs multiple functions: it monitors displacement volume, calculates optimal speed setpoints, and executes speed adjustments all in one unit. This multi-functionality consolidates control tasks, reducing the need for additional controllers and simplifying the overall system architecture.
Data Source
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AI summary
Method for operating a variable speed pump (120) in which a conveyor (122) adjustable in a displacement volume per working cycle is driven by means of a variable speed drive (121), wherein, within the framework of a control system, at least one variable is controlled by specifying a speed setpoint (nsetpoint) for a speed of the drive and a setpoint (αsetpoint) for a characteristic parameter determining the displacement volume per working cycle to a setpoint (psetpoint), wherein the speed setpoint (nsetpoint) is adjusted by means of a feedforward control as a function of a current speed of an adjustment of the conveyor (122) when the setpoint (αsetpoint) for the characteristic parameter determining the displacement volume per working cycle changes.