Multistage HVAC system with modulating device demand control
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Solution Overview
Problem
Existing building control systems for multistage heating or cooling processes often lead to user dissatisfaction due to suboptimal control decisions, resulting in reduced device lifetime and performance.
Innovation Solution
A controller system that identifies desired heating or cooling capacity, generates combinations of discrete and modulating device operations, sets make and break points, and generates control signals to optimize device usage, thereby ensuring efficient and prolonged operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If discrete devices are turned on and off in various combinations to achieve various capacities, then the desired heating or cooling capacity can be provided, but the lifetime and performance of devices suffer due to frequent switching and suboptimal control decisions
Solution Approach 1:
The system dynamically adjusts the operation of modulating devices based on real-time capacity requirements, transitioning from static on/off control to dynamic variable capacity control. This allows the system to meet varying heating or cooling demands while reducing frequent switching of discrete devices, thereby extending device lifetime and maintaining reliability.
Solution Approach 2:
The invention changes the control parameter from binary on/off states to continuous capacity modulation. By controlling modulating devices to operate at different capacity levels rather than simply on or off, the system can precisely meet capacity requirements while minimizing the number of discrete device transitions, thus improving device lifetime and performance.
2Productivity
If modulating devices are used to provide variable capacity, then the desired capacity can be achieved smoothly, but the system complexity increases due to coordination between discrete and modulating devices
Solution Approach 1:
The control system is segmented into distinct functional modules: a capacity identifier module that determines required capacity, a combination finder module that identifies suitable device combinations, and a controller module that executes the control logic. This modular segmentation manages system complexity by dividing the control task into manageable, independent functions while enabling smooth variable capacity provision.
Solution Approach 2:
The invention introduces an intermediary control system that acts as a mediator between the capacity requirements and the physical devices. This intermediary controller coordinates the operation of discrete and modulating devices, translating capacity demands into appropriate device combinations and modulation levels, thereby managing complexity while achieving smooth variable capacity output.
3Reliability
If optimal control decisions are implemented to extend device lifetime, then device performance is improved, but the control system complexity and computational requirements increase
Solution Approach 1:
The system performs preliminary actions by pre-identifying combinations of devices that can meet capacity requirements and pre-determining optimal control strategies. The combination finder module proactively identifies suitable device combinations before capacity demands change, allowing the controller to make optimal decisions without complex real-time calculations, thus extending device lifetime while managing control complexity.
Solution Approach 2:
The control system serves itself by automatically identifying capacity requirements, finding appropriate device combinations, and executing control decisions without external intervention. This self-service capability manages complexity through automated algorithms that systematically evaluate device combinations and select optimal configurations, extending device lifetime through consistent optimal control while reducing the burden of manual control management.
Data Source
AI summary
A controller for a plurality of devices of a building control system that operate in parallel to provide a desired capacity of heating or cooling for a building space includes a capacity identifier configured to identify the desired capacity of heating or cooling for the building space. The controller further includes a combination finder configured to generate a list of device combinations that can be energized to provide the desired capacity of heating or cooling. The controller further includes a combination filter configured to remove any combinations from the list of combinations that do not meet one or more requirements. The controller further includes a make and break point selector configured to set a series of make and break points. The controller further includes a signal generator configured to generate one or more control signals in accordance with the make and break points used to operate the plurality of devices.