Six-Way Valve Fallback Control for HVAC Sensor Fault Tolerance
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Solution Overview
Problem
HVAC systems face reduced efficiency and increased risk of sensor faults due to high fluid flow rates and complex sensor systems, which affect the accuracy of energy exchange regulation in heat exchangers.
Innovation Solution
A method and device for controlling the opening of a valve in HVAC systems that switches between default and fallback control modes based on sensor signal integrity, using a default control mode under normal conditions and switching to a fallback mode when sensor signals are faulty, allowing independent operation without faulty signals, and dynamically switching back when the sensors become valid again.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of sensors or sensor systems is increased to improve measurement precision, then the reliability of the HVAC system decreases due to increased risk of sensor faults
Solution Approach 1:
The patent implements a fallback control mode that is prepared in advance to compensate for potential sensor faults. When a sensor fault is detected, the system automatically switches to the fallback mode, which maintains HVAC operation using alternative control strategies that do not depend on the faulty sensor, thereby cushioning the impact of sensor failures on system reliability
Solution Approach 2:
The patent changes the control parameters dynamically based on sensor status. In normal operation, the system uses default sensor signals for precise control. When sensor faults occur, the system transitions to using alternative parameters or simplified control logic in the fallback mode, allowing the system to maintain functionality with reduced measurement precision but improved reliability
2Measurement precision
If complex sensor systems are used to improve measurement precision, then the device complexity increases
Solution Approach 1:
The patent segments the control system into two distinct modes: a default control mode for normal operation with full sensor functionality, and a fallback control mode for operation with sensor faults. This segmentation allows the system to use complex sensor systems when available while having a simplified alternative ready, reducing the need for continuously managing complex sensor configurations
3Productivity
If high fluid flow rates are used to increase productivity, then the efficiency of heat exchangers decreases
Solution Approach 1:
The patent implements dynamic control of valve opening based on actual system conditions and sensor feedback. The system continuously adjusts the valve position to optimize the balance between productivity and energy efficiency, preventing the fluid flow rate from becoming excessively high and causing heat exchanger efficiency to drop, while still maintaining high productivity when conditions permit
Data Source
AI summary
A method of controlling opening of a valve in an HVAC system is provided. The method includes controlling the opening of a six-way-valve according to a default control mode in dependence of a default sensor signal, the six-way-valve fluidicly coupling an inlet side and an outlet side of the heat exchanger alternatively with a first fluidic circuit in a first default control mode or a second fluidic circuit in a second default control mode; selecting a selected default control mode from the first default control mode and the alternative second default control mode; determining, while controlling the valve in the selected default control mode, whether the sensor signal is faulty; and switching, in case the signal is faulty, to controlling the opening according to a first fallback control mode or an alternative second fallback control mode, where the opening is controlled independently of the faulty sensor signal.