Sensorless Multipump Flow Rate Estimation via VSD Power Curves
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Solution Overview
Problem
Current multipump systems require unsatisfactory methods to measure the total flow rate at the outlet passage, often relying on flowmeters, necessitating a simpler and more minimalistic approach to estimate this flow rate without the use of sensors.
Innovation Solution
A control method implemented in a processing unit determines the total flow rate by using characteristic curves and power measurements from a variable speed drive, estimating the flow rate of each pump and combining them to calculate the total flow rate, without the need for a flowmeter or additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a flowmeter is used to measure the total flow rate at the outlet passage, then measurement precision is improved, but device complexity and installation requirements worsen
Solution Approach 1:
The invention extracts the flow measurement function from the physical outlet passage and relocates it to the variable speed drive's processing unit. Instead of measuring flow directly at the outlet using a flowmeter, the system calculates flow rate by processing electrical parameters (current, voltage, frequency) already present in the variable speed drive, thereby eliminating the need for external flow measurement devices
Solution Approach 2:
The invention introduces an intermediary calculation method that uses the relationship between motor power consumption and pump flow rate. The processing unit acts as an intermediary, converting electrical parameter measurements into flow rate information through characteristic curves and calculations, bridging the gap between electrical measurements and hydraulic parameters without direct flow sensing
2Measurement precision
If existing flow measurement methods are used, then total flow rate can be determined, but ease of operation and minimal installation are worsened
Solution Approach 1:
The variable speed drive performs self-service by using its own existing sensors and processing unit to determine the total flow rate. The system leverages the current and voltage sensors already integrated into the variable speed drive for motor control, eliminating the need for separate flow measurement equipment and simplifying installation while maintaining measurement accuracy
Data Source
AI summary
The invention relates to a control method implemented in a processing unit (UC) used in the control of a multipump system, said multipump system comprising an inlet passage (IN) intended to receive a fluid, two pumps (P1, P2) connected in parallel to said inlet passage and an outlet passage connected to the outlets of the two pumps (P1, P2), at least one of the two pumps being controlled by a variable speed drive (VSD), each pump (P1, P2) being defined by a first characteristic curve (HQcurve_n), flow rate-manometric head at maximum speed, and by a second characteristic curve (PQcurve_n), flow rate-received power. The control method provides for determining the total flow rate (Qtotal) of the multipump system without using sensors such as flowmeters.