Scroll Compressor Capacity Modulation With PWM Scroll Separation
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Solution Overview
Problem
Traditional capacity modulation systems in scroll compressors result in inefficient energy usage as the compressor continues to consume power during unloaded periods, even though it is not compressing or circulating refrigerant.
Innovation Solution
A method and system that modulate the capacity of a scroll compressor by determining target capacity ranges and operating the motor at different speeds, using pulse width modulation to periodically separate intermeshing scroll members and selectively releasing pressure from intermediate chambers, and optionally injecting refrigerant at higher pressure to match refrigeration system load, thereby optimizing compressor efficiency and power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If capacity modulation is achieved by separating scroll members or venting intermediate chambers, then compressor capacity is reduced to match system load, but the compressor continues to consume power during unloaded periods
Solution Approach 1:
The patent applies periodic action by using pulse width modulation (PWM) to periodically separate the scroll members and vent intermediate chambers. Instead of continuous operation, the system uses periodic on/off cycles where the compressor operates only when needed to match system load, reducing energy consumption during low-demand periods while maintaining capacity modulation effectiveness
Solution Approach 2:
The system dynamically adjusts compressor capacity by varying the PWM duty cycle based on real-time system load conditions. The control system continuously monitors refrigeration system requirements and dynamically modulates the separation frequency and duration of scroll members, transitioning from static capacity settings to adaptive dynamic control that optimizes both capacity and energy efficiency
2Speed
If the compressor operates at full speed to maintain readiness, then it can respond quickly to load changes, but energy consumption increases when full capacity is not needed
Solution Approach 1:
The system dynamically adjusts compressor speed and capacity modulation based on real-time load conditions. By using PWM control, the compressor can operate at optimal speeds only when necessary, rather than maintaining constant full-speed readiness, thereby reducing energy consumption while maintaining the ability to respond to load changes
Data Source
AI summary
A system and method for modulating capacity of a scroll compressor having a motor includes determining a target capacity of the scroll compressor, operating the motor at a first speed when the target capacity is within a first predetermined capacity range and at a second speed when the target capacity is within a second predetermined capacity range, determining a pulse width modulation cyclic ratio based on the target capacity and the first or second speed, and periodically separating intermeshing scroll members of the compressor according to the pulse width modulation cyclic ratio to modulate the capacity of the scroll compressor.