Compressor Motor Drive Parameter Control for Lubricant Refinement
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Solution Overview
Problem
Compressor systems face inefficiencies in lubricant refinement due to low discharge temperatures and refrigerant solubility issues, particularly at low pressure and volume ratios, which affect lubricant quality and rheological properties.
Innovation Solution
A compressor system with a controller that varies drive parameters such as pulse width modulation switching frequency, torque/amp ratio, and induction saturation curve to increase heat production, enhancing lubricant refinement by increasing discharge superheat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If motor operates at efficient parameters to reduce heat output, then motor efficiency is improved, but discharge temperature decreases making lubricant refinement difficult
Solution Approach 1:
The system dynamically adjusts motor operating parameters (voltage, frequency, current) to change the heat generation characteristics. By modifying these parameters, the motor can operate in different efficiency points, allowing discharge temperature to be increased when lubricant refinement is needed while maintaining efficient operation during normal conditions
Solution Approach 2:
The motor operating parameters are made dynamic rather than fixed. The control system continuously monitors discharge temperature and lubricant conditions, adjusting motor parameters in real-time to maintain optimal operating point that balances motor efficiency with sufficient discharge temperature for lubricant refinement
2Use of energy by moving object
If compressor operates at low pressure ratios and volume ratios, then energy consumption is reduced, but discharge superheat decreases reducing lubricant quality
Solution Approach 1:
The system implements feedback control by monitoring discharge superheat and lubricant conditions. When low pressure ratio operation causes insufficient superheat and degraded lubricant quality, the control system detects this through sensors and adjusts motor parameters or compressor operation to restore adequate superheat, ensuring lubricant quality is maintained across all operating conditions
Solution Approach 2:
The system takes preliminary action by monitoring lubricant conditions and predicting quality degradation before it occurs. When signs of deteriorating lubricant quality are detected during low pressure ratio operation, the control system proactively adjusts operating parameters to prevent further degradation, rather than waiting for actual failure
3Productivity
If modern refrigerants with higher solubility are used, then refrigeration efficiency is improved, but lubricant rheological properties deteriorate requiring higher temperatures for refinement
Solution Approach 1:
The system compensates for the higher solubility of modern refrigerants by dynamically adjusting motor operating parameters to increase discharge temperature when needed. This elevated temperature facilitates the separation of refrigerant from lubricant, counteracting the negative effect of higher solubility and maintaining proper lubricant rheological properties
Solution Approach 2:
The control system creates a virtual model of lubricant conditions based on operating parameters and refrigerant properties. This model predicts when lubricant refinement will be needed, allowing the system to pre-adjust motor parameters to achieve the necessary discharge temperature for effective lubricant separation, even with high-solubility refrigerants
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Improves lubricant quality and rheological properties by increasing discharge superheat, effectively separating lubricant from refrigerant and maintaining sufficient lubrication across various compressor operational conditions.
Implementation Method 1
The operation of the motor and the drive may result in inefficiencies at the motor that cause losses that generate waste heat
Implementation Method 2
The waste heat from the motor may be transferred to refrigerant entering the compressor
Implementation Method 3
varying the one or more drive parameters increases a heat produced by at least one of the motor and the drive
Data Source
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AI summary
This disclosure is directed to systems and methods for controlling compressor motors, particularly varying the operation parameters of the motor to provide heat to a lubricant of the motor. The operation parameters include one or more of a pulse width modulation switching frequency, a pulse width modulation frequency switching pattern, or a torque/amp ratio of a drive of the compressor. The efficiency of the motor may be reduced to provide heat, with the heat improving lubricant quality and drive efficiency, to increase an overall efficiency of compressor operations. Methods may include determining a lubricant quality, and determining operational parameters that improve lubricant quality.