Bearingless Motor Support for Compressor Driveshaft Shock Loads
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Solution Overview
Problem
HVACR compressors face challenges in managing increased loads on driveshafts due to abnormal flow conditions such as stall, surge, and shock loads, which can lead to instability and require larger magnetic bearings.
Innovation Solution
The use of a bearingless motor in combination with magnetic bearings, where the magnetic support is adjusted based on compressor operation, allows for efficient management of increased loads without the need for larger magnetic bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If larger magnetic bearings are used to support increased loads on the driveshaft during abnormal flow conditions, then the driveshaft stability is improved, but the device complexity and size increase
Solution Approach 1:
The magnetic bearing system dynamically adjusts its support characteristics based on operating conditions. During abnormal flow conditions (stall, surge, shock loads), the bearingless motor provides enhanced magnetic support to stabilize the driveshaft. This dynamic adaptation allows the system to maintain stability without requiring permanently larger magnetic bearings, thus resolving the contradiction between stability and device complexity.
Solution Approach 2:
The bearingless motor serves multiple functions: it provides rotational drive to the compressor and simultaneously provides magnetic support to the driveshaft. During abnormal flow conditions, it activates to provide additional stabilizing magnetic support. This multi-functionality allows the same component to address both drive and support needs, eliminating the requirement for separately oversized magnetic bearings.
2Reliability
If larger magnetic bearings are used to manage increased loads, then the compressor reliability under abnormal conditions is improved, but the electrical power consumption increases
Solution Approach 1:
The bearingless motor operates dynamically, providing magnetic support only when needed during abnormal flow conditions. This on-demand operation allows the system to maintain high reliability under stall, surge, and shock load conditions while consuming electrical power only during these abnormal conditions, rather than continuously operating at higher power levels that would be required by permanently larger magnetic bearings.
Solution Approach 2:
The system changes operational parameters by activating the bearingless motor's magnetic support function during abnormal conditions. This parameter change (from normal operation to enhanced magnetic support mode) provides the necessary reliability improvement without the continuous energy penalty that would result from using permanently oversized magnetic bearings.
3Device complexity
If traditional bearings are used to support the driveshaft, then the device complexity is reduced, but the ability to handle abnormal flow conditions and maintain stability deteriorates
Solution Approach 1:
The patent replaces traditional mechanical bearings with a magnetic bearing system integrated into the bearingless motor. This substitution provides enhanced stabilizing capability during abnormal flow conditions while maintaining relatively simple device architecture. The magnetic field-based support eliminates the need for complex mechanical bearing structures, thus resolving the contradiction between simplicity and stability under abnormal conditions.
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
This solution enables the compressor to operate efficiently at conditions near stall and surge, reducing electrical power consumption and maintaining stability without increasing magnetic bearing size.
Implementation Method 1
a bearingless motor configured to rotate the driveshaft to compress a working fluid
Implementation Method 2
one or more magnetic bearings for magnetically supporting the driveshaft when rotating
Data Source
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AI summary
A compressor includes a driveshaft, a bearingless motor, one or more magnetic bearings, and a controller for the bearingless motor. The bearingless motor configured to rotate the driveshaft to compress a working fluid. The one or more magnetic bearings magnetically support the driveshaft when rotating. The controller is configured to adjust magnetic support provided by the bearingless motor to the driveshaft based on operation of the compressor. A method of operating a compressor includes rotating, with a bearingless motor, a driveshaft to compress a working fluid and magnetically supporting, with one or more magnetic bearings, the driveshaft. The method also includes magnetically supporting, with the bearingless motor, the driveshaft in which the magnetic support provided by the bearingless motor is adjusted based on operation of the compressor.