Valve control in an HVAC system with sensors
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Solution Overview
Problem
HVAC systems face reduced efficiency due to high fluid flow rates and are vulnerable to sensor faults, which can lead to incorrect control of valve openings, affecting energy exchange and system performance.
Innovation Solution
A method and device that control the opening of a valve in an HVAC system by switching between default and fallback control modes based on sensor signal validity, using a default control mode under normal conditions and a fallback mode when sensor signals are faulty, ensuring continued operation and dynamic switching back to default mode when sensors become valid again.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors are used to control HVAC system parameters, then measurement precision and control accuracy are improved, but the risk of sensor faults increases
Solution Approach 1:
The control device stores alternative control strategies in advance that can be activated when sensor faults occur. These pre-prepared fallback strategies ensure continuous system operation without requiring real-time complex decision-making during fault conditions.
Solution Approach 2:
The system dynamically changes control parameters based on sensor availability. When sensors are functional, the system uses precise sensor-based control parameters; when sensors fail, it switches to alternative parameters such as fixed valve positions or simplified control algorithms that do not depend on the faulty sensors.
2Reliability
If complex control algorithms are used to handle sensor faults, then system reliability is improved, but device complexity increases
Solution Approach 1:
The control system is segmented into multiple independent control strategies: a primary control mode using sensor data, and several fallback control modes that can be activated independently when specific sensors fail. Each segment handles specific fault conditions, avoiding the need for a single complex fault-tolerance algorithm.
Solution Approach 2:
The system uses simple, easily implementable fallback control strategies that sacrifice some control precision but ensure continuous operation. These fallback strategies are designed to be computationally simple and easy to implement, prioritizing system availability over optimal performance during fault conditions.
3Productivity
If valve opening is continuously adjusted based on sensor feedback, then energy exchange efficiency is improved, but system vulnerability to sensor faults increases
Solution Approach 1:
The control system dynamically adapts its behavior based on sensor status. When sensors are functional, the valve opening is continuously adjusted for optimal energy exchange. When sensor faults are detected, the system automatically transitions to a less dynamic control mode with fixed or coarsely adjusted valve positions, maintaining stability while accepting reduced efficiency.
Solution Approach 2:
The system implements feedback not only from process sensors but also from the control system's own performance monitoring. When sensor faults are detected through feedback mechanisms, the system adjusts its control strategy to maintain stable operation, using feedback from alternative sensors or performance metrics to guide valve positioning.
Data Source
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AI summary
The present disclosure is directed towards a method of controlling opening of a valve (10) in an HVAC system (100). The method includes controlling the opening of the valve (10) according to a default control mode in dependence of a default sensor signal. The method further includes determining, while controlling the opening of the valve (10) according to the default control mode, whether the default sensor signal is faulty and switching, in case of the default sensor signal being faulty, to controlling the opening of the valve (10) according to a fallback control mode, with the opening of the valve (10) being controlled independently of the faulty sensor signal in the fallback control mode. The present invention is further directed towards a corresponding control device opening of a valve (10) in an HVAC system as well as a corresponding computer program product.