Method and system for swapping drives of motor-driven units of a motor driven unit system
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Solution Overview
Problem
Existing HVAC systems with multiple compressors face inefficiencies due to differing maintenance schedules and energy consumption disparities between variable and fixed speed compressors, leading to increased maintenance time and operational costs, particularly in mobile applications.
Innovation Solution
A control system with a swapping component that alternates the power supply between variable and fixed speed motors, allowing synchronized maintenance and balanced working hours through a VFD and a powering switch, enabling motors to swap roles dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a HVAC system uses one variable speed compressor and one fixed speed compressor, then energy efficiency is improved during variable demand, but maintenance complexity increases due to different maintenance schedules
Solution Approach 1:
The system dynamically swaps the operational roles of the two compressors based on accumulated operating hours. The controller monitors hours of operation and periodically exchanges which compressor runs at variable speed and which runs at fixed speed, ensuring both units accumulate similar operating hours and require maintenance simultaneously.
Solution Approach 2:
The system changes the operational parameters of the compressors by swapping their control modes. One compressor operates with variable speed control while the other operates at fixed speed, and these parameters are periodically exchanged to balance wear and maintenance requirements across both units.
2Ease of operation
If two variable speed compressors are used, then maintenance scheduling is simplified, but system cost and complexity increase due to requiring two VFDs
Solution Approach 1:
The system achieves the benefit of synchronized maintenance schedules by making one fixed speed compressor functionally equivalent to a variable speed compressor through role swapping. The fixed speed unit periodically takes on the variable speed role, ensuring both compressors accumulate similar operating hours without requiring both to be equipped with VFDs.
Solution Approach 2:
The system creates a functional copy of the variable speed operation capability in the fixed speed compressor by periodically swapping their operational roles. This allows the fixed speed compressor to experience similar operational stress and wear patterns as the variable speed compressor, enabling synchronized maintenance scheduling without duplicating the expensive VFD hardware.
3Device complexity
If two fixed speed compressors are used, then system simplicity is maintained, but energy efficiency deteriorates during variable demand conditions
Solution Approach 1:
The system introduces dynamic operational flexibility by periodically swapping the roles of the two fixed speed compressors. One compressor operates at variable speed while the other operates at fixed speed, and this configuration is periodically exchanged. This allows the system to benefit from variable speed energy efficiency during part-load conditions while maintaining the simplicity of having only two compressors without requiring both to be variable speed units.
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a control system (14) and a method for controlling an operation of motor-driven units of an MDU system (15), the latter comprising a first motor-driven unit (151) comprising a first motor (152) and a second motor-driven unit (153) comprising a second motor (154), said control system (14) comprising: - a variable frequency drive - hereafter VFD - (141) configured for outputting an electrical signal E1 configured for powering one motor among said first and second motors (152, 154), wherein a frequency of said electrical signal E1 is configured for varying in function of a control signal CD received by the VFD (141); - a powering switch (142) comprising two states, namely an ON state and an OFF state, wherein in the ON state, the powering switch (142) is configured for outputting an electrical signal E2 configured for powering the other motor among said first and second motors (152, 154), and in the OFF state, the powering switch (142) is configured for switching off said FS motor; characterized in that it further comprises - a swapping component (143) configured for switching the powering of the first motor (152) from the electrical signal E1 to the electrical signal E2 and of the second motor (154) from the electrical signal E2 to the electrical signal E1, and vice versa.