IPM Rotor Core Lamination for Torque and Centrifugal Strength
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Solution Overview
Problem
The challenge in IPM rotors is the difficulty in setting the positions and shapes of connection portions of the rotor core, which leads to magnetic flux leakage and reduced strength of outer core portions due to enlarged torque requirements.
Innovation Solution
A rotor design with laminated core sheets featuring first through-holes with connection portions and second through-holes without connections, supporting outer core portions at three locations, including newly-added connection portions and inherent connections, using bonded magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the widths of the connection portions are set to be small to reduce magnetic flux leakage, then magnetic flux leakage is reduced, but the connection portions become structurally weak and the strength of the outer core portions against centrifugal force decreases
Solution Approach 1:
The rotor core is divided into multiple core sheets that are laminated together. Each core sheet contains through-holes with connection portions that connect inner peripheral edges. This segmentation allows the magnetic flux leakage to be localized to specific connection portions while the overall structure maintains strength through the distributed lamination pattern.
Solution Approach 2:
The connection portions are formed by connecting inner peripheral edges in the width direction of the through-holes, creating a three-dimensional structural reinforcement. This dimensional approach allows the connection portions to provide structural support in multiple directions while maintaining small widths to minimize magnetic flux leakage.
2Power
If the outer core portions are enlarged to increase torque, then torque is increased, but the connection portions become more structurally weak against centrifugal force
Solution Approach 1:
The rotor core is segmented into multiple laminated core sheets, each contributing to the overall torque generation while distributing the centrifugal force loads. The through-holes with connection portions are strategically positioned to provide structural support to the enlarged outer core portions without compromising the torque-generating mass.
Solution Approach 2:
The connection portions are strategically positioned at specific locations within the rotor core structure to provide localized reinforcement. This allows the outer core portions to be enlarged for increased torque while maintaining structural integrity at critical connection points through the laminated core sheet design.
3Ease of manufacture
If a single type of core sheet is used for manufacturing, then manufacturing is simplified, but the ability to optimize both magnetic flux leakage and structural strength is reduced
Solution Approach 1:
A single type of core sheet is designed to perform multiple functions: generating torque through the folded permanent magnets, providing structural support through the laminated construction, and controlling magnetic flux leakage through the strategically positioned connection portions in the through-holes. This universal design simplifies manufacturing while addressing multiple technical requirements.
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 design enhances the strength of outer core portions against centrifugal force while maintaining torque generation, minimizing magnetic flux leakage, and simplifying manufacturing by using a single type of core sheet.
Implementation Method 1
The IPM rotors are configured to generate both magnet torque by the permanent magnets and reluctance torque by outer core portions
Implementation Method 2
The IPM rotors are configured to generate both magnet torque by the permanent magnets and reluctance torque by outer core portions
Implementation Method 3
Each of the first through-holes has a connection portion formed at an intermediate position in the folded shape of a corresponding one of the magnet-receiving holes to connect inner peripheral edges
Data Source
AI summary
A rotor includes: a rotor core including a plurality of core sheets that are laminated together and having a plurality of magnet-receiving holes formed in a folded shape; and a plurality of permanent magnets embedded respectively in the magnet-receiving holes. Each of the core sheets has a plurality of first through-holes and a plurality of second through-holes. Each of the first through-holes has a connection portion formed at an intermediate position in the folded shape of a corresponding one of the magnet-receiving holes to connect inner peripheral edges of the first through-hole that face each other in a width direction of the first through-hole. Each of the second through-holes has no connection portion. The core sheets are identical in configuration to each other. The core sheets are laminated so that each of the magnet-receiving holes is constituted of a mixture of the first and second through-holes of the core sheets.