Bus-Based HVAC Control Architecture for Easier Unit Upgrades
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Solution Overview
Problem
Conventional air conditioning systems incur high costs due to separate control devices in indoor and outdoor units, making system upgrades difficult as all units must have the same control program version.
Innovation Solution
An air conditioning system with independently existing outdoor and indoor unit control sections that communicate via a common medium, allowing for simplified configurations, reduced costs, and easy upgrades, featuring a protection control mechanism for emergency stops and anti-frost functions, and virtualized control sections to optimize CPU resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If separate control devices are provided in each indoor unit and outdoor unit, then control functions can be distributed and system autonomy is improved, but device complexity and cost increase
Solution Approach 1:
The control system is segmented into a central control device that manages multiple indoor and outdoor units. Each unit has a simplified control section rather than a full control device, dividing the control functionality between central and distributed elements to reduce overall complexity while maintaining autonomy
Solution Approach 2:
Multiple control functions for different indoor and outdoor units are merged into a single central control device. This consolidation reduces the total number of control devices needed, simplifying the system while preserving distributed control capabilities through communication between the central device and unit-level control sections
2Reliability
If all indoor units and outdoor units have the same control program version, then system compatibility and stability are maintained, but adaptability to new control specifications is reduced
Solution Approach 1:
The control program is extracted from the individual units and placed in the central control device. This allows the central device to run updated control specifications while the units themselves maintain their hardware integrity, enabling independent software updates without requiring unit replacement
Solution Approach 2:
The control system is made dynamic by allowing the central control device to update its control program independently of the units. This enables the system to adapt to new specifications over time while maintaining backward compatibility with existing units through communication protocols
3Speed
If control sections are integrated into each unit, then real-time local control decisions can be made, but manufacturing cost and system complexity increase
Solution Approach 1:
Control functionality is segmented between a central control device that handles complex decision-making and simplified control sections in each unit that execute local commands. This segmentation allows real-time local response with minimal hardware in each unit, reducing manufacturing costs while maintaining speed
Solution Approach 2:
The central control device acts as an intermediary that sends control instructions to units and receives status information. This mediator approach allows complex control logic to reside centrally while units maintain simple, fast local execution capabilities, balancing response speed with manufacturing simplicity
Data Source
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AI summary
An air conditioning system (1) includes indoor units (A1, A2), an outdoor unit (B), and a control device (3). Indoor unit control sections (41, 42), which respectively control the indoor units (A1, A2), and an outdoor unit control section (43), which controls the outdoor unit (B), are consolidated into the control device (3). The outdoor unit (B) is provided with an outdoor protection control section (64) that stops a compressor when an emergency stop condition is satisfied. The control device (3), the indoor units (A1, A2), the outdoor unit (B), and sensors (20) are adapted to be able to send and receive information to and from one another via a common bus (5). The indoor unit control sections (41, 42) and the outdoor unit control section (43) in the control device (3) acquire information from the sensors (20) via the common bus (5), and respectively create control instructions to various equipment constituting the indoor units (A1, A2) and the outdoor unit (B) by executing respective control programs.