Controller and method for managing a flow unit
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Solution Overview
Problem
Conventional building automation systems face challenges in maintaining optimal control performance across varying system conditions, often resulting in either over-cycling or slow reaction times, especially when dealing with airflow control in HVAC systems, which can lead to higher energy costs and inefficient operation.
Innovation Solution
A dynamic calculation of nominal flow approach is implemented, allowing for consistent control performance across changing conditions by calibrating and adjusting the control loop parameters based on measured flows and positions of the flow control elements, eliminating the need for extensive tuning in high-performance systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed nominal setpoint is used for control tuning, then the device is optimized for a fixed system design condition, but it does not work well when the system resets the design condition to optimize for other conditions such as energy efficiency
Solution Approach 1:
The patent implements dynamic nominal flow calculation that automatically adjusts control parameters based on real-time measured flow and position data. The system transitions from fixed control tuning to adaptive control by continuously calculating dynamic nominal flow values using the relationship between measured flow, calibration data, and current operating conditions. This enables the controller to maintain optimal performance across varying system conditions including energy efficiency optimizations.
2Speed
If the controller is tuned at the upper end of the design operating condition range, then it responds in a timely manner to errors at that range, but it is slow to react when the system is in the lower end of the design condition range
Solution Approach 1:
The patent applies local quality by tailoring control parameters to specific operating conditions. The dynamic nominal flow calculation uses calibration data collected at multiple flow control element positions to create position-specific control characteristics. This ensures optimal reaction speed at each operating point rather than compromising performance across the entire range, as the controller adapts its nominal flow values based on the current position and measured flow.
3Adaptability or versatility
If a Venturi air valve is used for self-adjustment, then the valve can adapt to changing system conditions, but it comes at a higher energy operating cost for the system
Solution Approach 1:
The patent replaces the mechanical Venturi air valve self-adjustment mechanism with a control system that uses sensors and computational algorithms. Instead of relying on differential pressure drops across a Venturi geometry to drive self-adjustment, the system uses measured flow data and calibration information to calculate dynamic nominal flow values electronically. This substitution eliminates the energy penalty associated with Venturi valve operation while maintaining adaptability to changing system conditions.
Data Source
AI summary
There is described a controller and method for managing a flow unit. A measured full flow corresponding to a full open position of a flow control element of the flow unit is detected. A calibration nominal is established based on the measured full flow, and calibration relative flows are calculated based on the calibration nominal and calibration measured flows corresponding to calibration positions of the flow control element. Subsequent to calibration, an operation measured flow of the flow unit and an operation position of the flow control element are detected. A dynamic nominal is determined based on the operation measured flow and a particular calibration relative flow corresponding to the operation position of the flow control element. The operation position of the flow control element is controlled based on the operation measured flow and the dynamic nominal.