Rotary Electric Machine Rotor Core Segmentation for Torque and Stress
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Solution Overview
Problem
Rotating electric machines with embedded magnets face challenges in generating large reluctance torque while maintaining low stress and high power factor, leading to increased inverter and battery capacity requirements.
Innovation Solution
A rotating electric machine design featuring a rotor core with distributed winding and strategically placed permanent magnets, which reduces stress and enhances power factor by utilizing reluctance torque effectively across a wide range of rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the rotor core structure is made complicated to obtain larger reluctance torque, then the reluctance torque is improved, but the stress generated due to centrifugal force increases and rotational speed becomes difficult to increase
Solution Approach 1:
The rotor core is segmented into multiple yokes (first yoke, second yoke, third yoke, fourth yoke) arranged circumferentially, with permanent magnets positioned between them. This segmentation allows the rotor to achieve large reluctance torque through the magnetic circuit configuration while distributing centrifugal stress across multiple smaller components rather than one large complex structure, enabling high-speed rotation.
2Force
If the rotor core structure is made complicated to obtain larger reluctance torque, then the reluctance torque is improved, but the inductance increases causing power factor deterioration
Solution Approach 1:
The invention positions permanent magnets specifically in the q-axis direction between the yokes, creating localized magnetic fields that generate reluctance torque without requiring a complicated overall rotor structure. This localized approach maintains simpler magnetic circuits with lower inductance, thereby improving power factor while still achieving large reluctance torque through strategic magnet placement and yoke configuration.
3Stress or pressure
If simpler rotor core structure is used to reduce stress and improve power factor, then stress is reduced and power factor is improved, but reluctance torque becomes smaller
Solution Approach 1:
The invention creates a dynamic magnetic circuit configuration where four yokes are arranged circumferentially with permanent magnets positioned between them. This dynamic arrangement allows the magnetic flux to change direction and magnitude as the rotor rotates, generating large reluctance torque through the interaction between the permanent magnets and the stator magnetic field, while maintaining a relatively simple rotor core structure that reduces centrifugal stress and improves power factor.
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
The design achieves improved reluctance torque, reduced stress, and enhanced power factor, enabling high output performance without the need for increased inverter and battery capacity.
Implementation Method 1
a rotor (250) including: a rotor core (252); permanent magnets (254)
Implementation Method 2
can generate a large torques in low-speed rotation regions and can achieve high output also in high-speed rotation regions
Data Source
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AI summary
A rotating electric machine, which can achieve improvement of a reluctance torque, reduction of stress and improvement of a power factor at the same time, and can also realize high output, and an electrically driven vehicle having the rotating electric machine are provided. A permanent magnet is arranged on a q-axis that connects magnetic poles of a rotor; a gap is formed in a radial direction of the permanent magnet; another permanent magnet is arranged facing the said permanent magnet so that these permanent magnets may sandwich a d-axis which connects centers of the magnetic poles; and another gap is formed at a position corresponding to a position of the said gap. Further, a first virtual line that coincides with a boundary of a permanent magnet insertion hole, which is arranged facing the d-axis, on an inner circumference side of a rotor core; and a second virtual line that is concentric with an inner circumference of the rotor core and contacts the first vertical line are set so that the second virtual line on the innermost circumference and the first virtual line have two or more tangent points.