Multi-gap Rotary Electric Machine with Segmented Magnetic Circuits
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Solution Overview
Problem
Conventional double-stator IPM motors face challenges in increasing power density due to inefficient use of reluctance torque and are prone to magnet demagnetization, particularly in the inner magnets, due to magnetic saturation and leakage, which impairs motor performance.
Innovation Solution
A multi-gap type rotary electric machine design with an annular rotor core and full-pitch windings in both stators, where inner and outer magnets are embedded at equal pitches, and salient poles are formed between adjacent magnets, ensuring the pole pitch of the rotor matches the magnetic field generated by the stators, thereby optimizing both magnet torque and reluctance torque usage, and minimizing magnetic saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the rotor yoke width is reduced to increase power density, then the motor size is reduced, but the rotor yoke becomes saturated with magnetic flux, which decreases the reluctance torque
Solution Approach 1:
The magnetic flux paths are segmented into separate inner and outer circuits with dedicated salient poles for each. This segmentation distributes the magnetic flux more evenly throughout the rotor yoke, preventing localized saturation and allowing the rotor yoke to be thinner without losing reluctance torque performance
2Device complexity
If the stator winding is configured as short-pitch winding, then the device complexity is reduced, but the pole pitch of the rotor does not coincide with the pole pitch of the magnetic field generated by the stator windings, which prevents full utilization of reluctance torque
Solution Approach 1:
The winding pitch parameter is changed from short-pitch to full-pitch configuration. This parameter change ensures that the pole pitch of the rotor coincides with the pole pitch of the magnetic field generated by the stator windings, enabling full utilization of reluctance torque while maintaining manageable device complexity
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 output torque, reduces motor size, and increases power density by effectively utilizing both magnet and reluctance torques while preventing magnet demagnetization, thus improving the motor's performance and resistance to demagnetization.
Implementation Method 1
The IPM motors can use reluctance torque that is a core attractive force, in addition to magnet torque that is generated by magnets
Implementation Method 2
The IPM motors can use reluctance torque that is a core attractive force, in addition to magnet torque that is generated by magnets
Data Source
AI summary
A multi-gap type rotary electric machine is provided, where the machine is provided a shaft supported rotatably by a baring secured to a housing. An annular rotor is secured to the shaft and configured to rotate together with the shaft. Double stators are secured to the housing and configured to have gaps between the stators and the rotor. Relationships of:3.5<P13/P6 (1) andP7/P6>1 (2)are met, where P6 denotes a circumferential width of each of outer salient poles, P7 denotes a circumferential width of each of inner salient poles, and P13 denotes a circumferential width of each of the outer magnets.