Rotary Compressor Torque Control for Axial Thrust Limits
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Solution Overview
Problem
Rotary compressors in refrigeration systems experience axial thrust forces due to rapid changes in rotational velocity, leading to potential failure and excessive wear, as the rotors can contact unintended surfaces, increasing the load on bearings and reducing compressor reliability.
Innovation Solution
Implementing a control method that regulates the acceleration and deceleration torque of the rotors within predefined limits by controlling the motor's speed and torque, using sensors to monitor operational parameters and adjust the speed profile to prevent axial thrust movement, thereby reducing wear and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the rotational velocity of the rotors changes rapidly to improve compressor responsiveness, then the compressor can adapt faster to load changes, but axial thrust forces increase causing rotor contact with unintended surfaces and excessive wear
Solution Approach 1:
The control system pre-establishes acceleration and deceleration torque limits to prevent excessive axial thrust forces before they occur. By setting predefined torque boundaries during system initialization or operation, the controller proactively prevents rotor contact with unintended surfaces, thereby maintaining reliability while allowing responsive speed changes.
Solution Approach 2:
The system dynamically adjusts the acceleration and deceleration torque commands based on real-time operating conditions while maintaining predefined limits. The controller continuously monitors rotor speed and torque, adjusting the rate of change dynamically to prevent axial thrust forces from exceeding safe thresholds, thus resolving the contradiction between rapid responsiveness and reliability.
2Productivity
If the acceleration and deceleration torque limits are increased to improve compressor responsiveness, then the compressor can change speed faster, but axial rotor movement increases causing contact with unintended surfaces
Solution Approach 1:
The system changes the operational parameters by establishing predefined acceleration and deceleration torque limits that constrain the rate of change of rotor speed. By modifying these torque parameters, the controller enables faster responsiveness while preventing axial rotor movement from exceeding safe thresholds, thus avoiding contact with unintended surfaces.
Solution Approach 2:
The control system continuously monitors rotor position, speed, and torque, and uses this feedback to adjust acceleration and deceleration commands in real-time. When approaching predefined torque limits that would cause excessive axial movement, the controller reduces the rate of change, thereby maintaining productivity while preventing harmful rotor contact.
3Force
If bearing capacity is increased to support higher axial thrust forces, then the compressor can tolerate greater axial loads, but the device complexity and cost increase
Solution Approach 1:
Instead of designing bearings to withstand high axial thrust forces, the invention converts the potentially harmful axial forces into beneficial controlled torque commands. By limiting acceleration and deceleration torque within predefined boundaries, the system transforms what would be destructive forces into controlled operational parameters, eliminating the need for complex high-capacity bearings.
Solution Approach 2:
The invention replaces the mechanical solution of increasing bearing capacity with a control system solution. Rather than relying on mechanical robustness to handle axial thrust forces, the system uses electronic control to preemptively limit torque commands, thereby substituting a complex mechanical bearing system with a simpler control algorithm that achieves the same protective function.
Data Source
AI summary
Systems and methods are used to control operation of a rotary compressor of a refrigeration system to limit or prevent movement of rotors due to axial thrust loading resulting from rapid changes in speed of the rotors of the compressor. The operational profile of the motor is controlled to maintain acceleration torque and deceleration torque within predefined limits. The acceleration torque and deceleration torque are maintained within the predefined limits by controlling the speed of the motor, or by controlling the torque applied by the motor to the rotors during acceleration or deceleration.