Embedded permanent magnet-type electric motor, compressor, and refrigeration/air-conditioning device
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Solution Overview
Problem
The use of arc-shaped permanent magnets in motors leads to unbalanced magnetic flux density on the rotor outer peripheral surface, causing vibration due to the concentration of magnetic flux and demagnetization of surface ends, resulting in unbalanced rotor magnetic attraction force.
Innovation Solution
The formation of slits on the rotor outer peripheral surface, extending from the magnet insertion holes, reduces the linkage of stator magnetic flux with the core regions on the radially outer side of the permanent magnets, thereby reducing unbalance in magnetic attraction force and vibration, while maintaining high magnetic flux density through sinusoidal distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If arc-shaped permanent magnets are arranged with convex portion toward radially inner side to increase magnetic flux and driving torque, then driving torque increases, but unbalance in magnetic flux density occurs on rotor outer peripheral surface causing vibration
Solution Approach 1:
The rotor core is segmented into multiple core regions by forming slits that extend from the radially outer side of magnet insertion holes toward the rotor outer peripheral surface. This segmentation divides the core regions located on the radially outer side of permanent magnets into separate sections, preventing concentrated magnetic flux and reducing unbalance in magnetic flux density on the rotor outer peripheral surface, thereby reducing vibration while maintaining the arc-shaped magnet configuration for high driving torque
Solution Approach 2:
Different regions of the rotor core are given different magnetic properties through selective slit formation. The core regions on the radially outer side of permanent magnets are modified with slits to reduce magnetic flux concentration, while other regions maintain their original properties. This local modification allows the system to reduce vibration in specific areas without compromising the overall magnetic flux generation capability of the arc-shaped permanent magnets
2Object-affected harmful factors
If slits are formed in rotor core to reduce unbalance in rotor magnetic attraction force, then vibration decreases, but magnetic flux linkage is reduced
Solution Approach 1:
Slits are formed only in specific core regions located on the radially outer side of permanent magnets, while leaving other core regions intact. This localized approach modifies magnetic flux distribution only where needed to reduce unbalance and vibration, without significantly impacting the overall magnetic flux linkage between stator and rotor
Solution Approach 2:
The slits segment the core regions into smaller sections, creating multiple flux paths rather than blocking flux entirely. This segmentation approach reduces magnetic flux concentration and unbalance while maintaining adequate magnetic flux linkage for driving torque generation
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 unbalance in magnetic flux density, reducing vibration and demagnetization, while maintaining high driving torque and efficiency by optimizing the slit shape and arrangement to minimize stator magnetic flux linkage.
Implementation Method 1
the magnetic flux generated by a stator coil is hardly linked
Implementation Method 2
when the slits are formed, a path of the magnetic flux is blocked
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Provided is an interior permanent magnet motor, including: a rotor including a permanent magnet; and a stator. The rotor further includes a rotor core. The rotor core has a magnet insertion hole and a plurality of slits. The plurality of slits are arranged in a region of the rotor core, which is located on a radially outer side of each magnet insertion hole. The magnet insertion hole is curved into an arc shape, and a convex portion side of the arc shape is arranged on a center side of the rotor. The magnet insertion hole has a first line, a second line, and a pair of third lines. The first line is located on the radially outer side of the second line. Each of the third lines connects the first line and the second line to each other. The first line includes an arc portion and a pair of concave portions. Each of the concave portions is located at an end of the arc portion of the first line.