Permanent Magnet Rotary Machine Thermal Management
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Solution Overview
Problem
Permanent magnet rotating machines face thermal degradation due to heat generated by windings and iron cores, leading to decreased efficiency and reliability, as the temperature rise from the air intake to the exhaust port side affects the magnetic properties of the magnets.
Innovation Solution
The design incorporates a housing with an air intake port and an air exhaust port, where the permanent magnet at the air exhaust port side has a higher coercivity than at the air intake port side, utilizing a surface treatment by grain boundary diffusion to maintain remanence levels while increasing coercivity, and using a blower to feed cooling air through the machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is fed through the housing from air intake port to air exhaust port, then heat generated by windings and iron core is cooled, but the temperature rise of cooling air causes thermal degradation of permanent magnets especially at the air exhaust port side
Solution Approach 1:
The patent applies local quality by differentiating the coercivity requirements of permanent magnets based on their position relative to the air exhaust port. Specifically, permanent magnets located at or near the air exhaust port side are designed with higher coercivity than those at the air intake port side. This localized differentiation addresses the thermal gradient caused by cooling air temperature rise, providing enhanced thermal stability where it is most needed while maintaining cost-effectiveness throughout the entire magnet array.
2Reliability
If alloying process by grain boundary diffusion is used to increase coercivity, then heat resistance and demagnetization resistance are improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent implements local quality in the manufacturing approach by applying the alloying process by grain boundary diffusion selectively only to permanent magnets located at or near the air exhaust port side, rather than uniformly to all permanent magnets. This targeted application reduces manufacturing complexity and cost while still achieving the necessary coercivity enhancement in the specific regions where thermal degradation is most severe.
Solution Approach 2:
The patent utilizes parameter changes by modifying the coercivity parameter of permanent magnets based on their spatial position and thermal environment. By adjusting the coercivity parameter (through selective alloying) in regions experiencing higher temperatures, the patent optimizes the balance between magnetic performance and thermal resistance without unnecessarily increasing complexity throughout the entire device.
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 configuration effectively suppresses thermal degradation and efficiency drops in permanent magnet rotating machines, allowing for improved reliability and performance by maintaining magnetic properties and reducing costs through targeted coercivity enhancement.
Implementation Method 1
an alloying process by grain boundary diffusion is known as a method for manufacturing an R-Fe-B sintered magnet having a high coercivity
Implementation Method 2
a permanent magnet is cooled by feeding cooling air thereto by use of a blower
Implementation Method 3
a blower for feeding the cooling air to the air intake port
Data Source
Figure 1~2
Figure 3
Figure 4(A)~4(C)
AI summary
Provided is a technology for enhancing the reliability of a permanent magnet rotating machine against thermal degradation of a permanent magnet. Specifically, provided is a permanent magnet rotating machine comprising a housing which houses a rotation shaft, a rotor connected to the rotation shaft and configured to rotate together with the rotation shaft, a stator, and permanent magnets fastened to the rotor or the stator; an air intake port provided at one end of the housing and an air exhaust port provided at the other end of the housing, the air intake port and the air exhaust port being configured to allow cooling air to flow through the housing; and a blower for feeding the cooling air to the air intake port; wherein the permanent magnet rotating machine is configured to be driven by magnetic force of the permanent magnets, and among the permanent magnets, a permanent magnet in the air exhaust port side has a higher coercivity than a permanent magnet in the air intake port side.