Pump Head Control at Low Flow Rates to Cut Idle Power
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Solution Overview
Problem
Existing pump control methods consume unnecessary power when operating at very low volume flows, as they maintain a high target delivery head even when valves are closed, leading to inefficient energy use.
Innovation Solution
A method that adjusts the target delivery head of an electric motor-driven pump based on a preset characteristic curve, reducing it when volume flow falls below a reference value, allowing for targeted reduction in pump output and energy efficiency by lowering the delivery head or reducing pump speed, and switching to a minimum delivery head value or temporarily switching off the pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the pump is controlled along a preset characteristic curve with target delivery head kept constant or linearly dependent on volume flow, then the hydraulic performance adapts to volume flow requirements, but unnecessary power is consumed at very low volume flows when valves are closed
Solution Approach 1:
The control method dynamically adapts the target delivery head based on the actual operating conditions. When volume flow drops below a reference value (at most one tenth of maximum volume flow), the controller lowers the target delivery head below the preset characteristic curve. This dynamic adjustment allows the pump to reduce power consumption at very low flows while maintaining sufficient pressure for system observability through minimum delivery head values.
Solution Approach 2:
The invention changes the control parameter (target delivery head) based on the operating regime. By detecting when volume flow falls below the reference value, the system transitions from following the preset characteristic curve to operating with a lowered target delivery head, eventually reaching a minimum delivery head value that ensures system observability while minimizing energy consumption.
2Use of energy by moving object
If the target delivery head is lowered at very low volume flows to reduce power consumption, then energy efficiency improves, but the pump may lose ability to maintain sufficient pressure for system observability
Solution Approach 1:
The pump delivers a minimum delivery head value that is sufficient for system observability rather than the full delivery head that would be required for maximum performance. This partial action approach maintains just enough pressure to detect system changes and observe pump operation, while avoiding the excessive power consumption that would result from maintaining higher delivery head at very low volume flows.
Data Source
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AI summary
The invention relates to a method for operating a pump that is driven by an electric motor in a hydraulic system in a power-optimized manner in the event of very low volumetric flow rates (Q). The target delivery head (H) of the pump is regulated along a preset characteristic curve (K) dependent on the volumetric flow rate (Q). The target delivery head (H) is reduced compared to the preset characteristic curve (K) if the volumetric flow rate (Q) falls short of a reference value (Q_ref) that is maximally a tenth, preferably a twentieth of the maximum volumetric flow rate (Q_max) on the characteristic curve (K). The reduction is carried out as long as the volumetric flow rate (Q) lies below the volumetric flow rate reference value (Q_ref) and a delivery head minimum value (H_min) has not been reached. The invention further relates to a pump that is driven by an electric motor, comprising a control and regulating electronic system that is equipped to carry out said method, and to a computer program product with instructions for carrying out the method for operating a pump that is driven by an electric motor when said method is carried out in a control and regulating electronic system of the pump.