Environmental control system with anti-windup structure
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Solution Overview
Problem
Current HVAC systems face challenges in accurately delivering heating/cooling capacity due to air flow constraints, leading to over-provisioning by system demand controllers, which can result in inefficient operation and damper actuation.
Innovation Solution
A capacity controller is introduced to manage damper positions and equipment operation based on zone demands and available capacity, using proportional integral controllers and anti-windup techniques to optimize air flow and equipment usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the system demand controller increases heating/cooling capacity output, then the capacity demand of zones is met, but air flow constraints prevent effective delivery to zones
Solution Approach 1:
The system implements feedback control by continuously monitoring zone temperatures, damper positions, and air flow conditions. The capacity controller adjusts heating/cooling capacity output based on feedback from zone controllers and damper status, ensuring capacity is increased only when zones can effectively receive and utilize it, preventing the mismatch between capacity output and effective delivery.
Solution Approach 2:
The system dynamically adjusts damper positions and capacity controller settings in real-time based on changing zone demands and air flow conditions. The capacity controller modulates equipment operation dynamically, and dampers adjust their positions continuously rather than in fixed stages, allowing the system to adapt to varying conditions and maintain optimal matching between capacity output and delivery capability.
2Ease of operation
If the system uses exceptional rules to satisfy air flow constraints, then damper actuation is controlled, but system efficiency decreases due to over-provisioning
Solution Approach 1:
The capacity controller serves as an intermediary between the zone controllers and the heating/cooling equipment. It receives capacity requests from zone controllers, adjusts them based on overall system capacity and air flow constraints, and then commands the equipment accordingly. This intermediary role prevents over-provisioning by coordinating capacity output with actual delivery capability across all zones, eliminating the need for inefficient exceptional rules at the zone level.
Solution Approach 2:
The system performs preliminary assessment of air flow constraints and equipment capacity before commanding full capacity output. The capacity controller evaluates current damper positions, air flow conditions, and equipment capabilities in advance, and only commands heating/cooling capacity that can be effectively delivered. This preliminary action prevents energy waste from producing capacity that cannot be utilized.
3Productivity
If zone controllers open dampers to meet noise limits, then air flow to zones is controlled, but system demand controller cannot deliver sufficient capacity
Solution Approach 1:
The system merges the control functions of zone controllers and the system demand controller into a coordinated hierarchy. The capacity controller combines information from all zone controllers about their capacity demands and air flow constraints, then coordinates the overall equipment output and damper positioning. This merged control approach ensures that individual zone air flow control requirements do not conflict with system-wide capacity delivery needs.
Data Source
AI summary
An environmental control system is provided and includes equipment to generate an environmental control effect, a damper associated with a zone to control a portion of the environmental control effect permitted to affect the zone by assuming one of various damper positions and a capacity controller operably coupled to the equipment and the damper to control operation of the equipment and to adjust the damper to assume the one of the various damper positions based on a demand of the zone and a capacity of the equipment.