Sensorless Centrifugal Machine BEP Control Using Estimated Torque
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Solution Overview
Problem
Existing fluid management systems lack efficient control mechanisms for centrifugal machines that do not rely on sensors and can optimize operating points based on pre-determined performance data to achieve optimal efficiency.
Innovation Solution
A control system that includes a controller to determine the operating point of a centrifugal machine using estimated torque and speed, comparing it to a best efficiency point (BEP), and adjusting the motor speed to optimize efficiency without sensor input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor-based feedback control is used to optimize operating points, then control precision is improved, but device complexity and cost increase
Solution Approach 1:
The centrifugal machine determines its own operating point by calculating head and efficiency from readily available operational parameters (flow rate, power consumption, speed) without requiring external sensors for direct measurement. The system uses pre-determined performance data and mathematical relationships to self-assess its operating state and identify the best efficiency point.
Solution Approach 2:
The patent replaces physical sensor-based measurement systems with a computational approach that uses electrical power measurements and flow rate data combined with pre-stored performance characteristics to determine operating points. This substitution eliminates the need for complex mechanical or physical sensing infrastructure while achieving the same control objective.
2Device complexity
If pre-determined performance data is used to determine operating points, then device complexity is reduced, but measurement precision may be compromised
Solution Approach 1:
Performance data including head-flow relationships and efficiency characteristics are pre-determined and stored in memory during manufacturing or commissioning. This preliminary action allows the control system to quickly reference accurate performance curves without performing complex real-time calculations or requiring extensive sensor arrays, thereby simplifying the operational control system while maintaining precision.
Solution Approach 2:
The patent creates a digital copy of the centrifugal machine's performance characteristics (head curves, efficiency maps) and stores it in the controller's memory. This copied performance data serves as a reference model that the system uses to determine operating points by comparing actual operational parameters against the stored performance profiles, achieving accurate control without complex real-time sensing.
3Loss of energy
If motor speed is adjusted to maintain operating point at BEP, then energy efficiency is improved, but device complexity increases due to speed control mechanisms
Solution Approach 1:
The system dynamically adjusts the motor speed to maintain the centrifugal machine's operating point at or near the best efficiency point (BEP). By continuously monitoring flow rate and power consumption against pre-stored performance data, the controller modifies operational parameters in real-time to optimize efficiency while adapting to changing system conditions and demands.
Solution Approach 2:
The patent optimizes energy efficiency by changing the operational parameters (motor speed, flow rate) to keep the operating point aligned with the best efficiency point characteristics stored in memory. This parameter adjustment approach allows the system to achieve optimal energy efficiency across varying load conditions without requiring complex additional control hardware, as it leverages the existing drive system's ability to adjust speed.
Data Source
AI summary
A control system includes: a controller configured to: access an estimated torque and estimated speed of a motor mechanically coupled to an impeller of a centrifugal machine; access at least one set of pre-determined performance data values associated with a known speed of the impeller, where each set of pre-determined performance data values includes: a plurality of flowrate values and a plurality of performance metric values; determine an operating point of the centrifugal machine based on the estimated torque, the estimated speed, and the at least one set of pre-determined performance data values; compare the determined operating point to a best efficiency point (BEP) associated with the centrifugal machine; and determine whether to change the speed of the motor based on the comparison.