Doubly Salient Permanent Magnet Machine with Segmented Movers
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Solution Overview
Problem
Conventional linear electric machines face increased production costs and pulsations of thrust and normal force due to the need for more permanent magnets as the mover distance increases, and they suffer from end effects that hinder precision position control.
Innovation Solution
The design incorporates a stator with alternating permanent magnets and salient poles, and includes first and second movers with a 60° phase angle difference, reducing the number of permanent magnets and mitigating thrust pulsations by arranging phase coils in specific configurations around mover teeth, with the option for integrated or separated movers and stators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the distance that the mover moves is increased, then the number of permanent magnets used is increased, but production cost increases
Solution Approach 1:
The mover is divided into two separate movers (first mover and second mover) that are arranged at positions spaced apart by an electrical phase angle of 60°. Each mover has its own phase coils, and together they cover a wider range while using fewer permanent magnets on the stator. This segmentation allows the system to achieve longer effective mover distance without proportionally increasing the number of permanent magnets.
2Length of moving object
If the number of permanent magnets is increased, then production cost increases, but this is required to increase mover distance
Solution Approach 1:
The system uses two movers with phase angle difference to extend the effective range without adding more permanent magnets. The phase coils of the two movers are controlled with 60° electrical phase difference, allowing them to operate in sequence or parallel to achieve longer travel distance while keeping the permanent magnet count fixed, thereby reducing production cost.
Solution Approach 2:
The invention changes the operational parameters by introducing a phase angle difference of 60° between the two movers. This parameter change allows the same permanent magnets to serve multiple positions along the travel path, effectively extending the mover distance capability without increasing the quantity of permanent magnets or production cost.
3Force
If conventional mover structure is used, then thrust pulsation occurs due to end effect, but precision position control is hindered
Solution Approach 1:
The thrust generation is segmented into two separate movers with phase angle difference. The end effects that cause thrust pulsation in a single mover are distributed and mitigated when the two movers operate with 60° phase difference. This segmentation smooths out the thrust profile and reduces pulsation, enabling better precision position control.
Solution Approach 2:
The two movers operate with a periodic phase difference of 60°, creating a combined thrust pattern that reduces pulsation. The periodic switching and coordination between the two movers with fixed phase difference smooths the overall thrust output, mitigating the end effect induced pulsations and improving position control precision.
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 reduces the number of permanent magnets needed by half, decreases thrust and normal force pulsations, and allows for precise position control by canceling attractive forces, while maintaining comparable thrust levels to conventional designs.
Implementation Method 1
each phase coil is wound around one of the mover teeth and the phase coils are arranged in the order of phases U, V, W, /V, /W and /U
Implementation Method 2
the stator comprises an iron core having a plurality of salient poles, with permanent magnets provided in depressions defined between the salient poles
Data Source
Figure 1~2
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Figure 5~6
AI summary
Disclosed herein is a linear, curved or rotary electric machine. The electric machine includes first and second movers which are adjacent to each other and have a phase angle difference of 60° therebetween. The first mover includes phases U, V and W and the second mover includes phases /U, /V and /W. The electric machine of the present invention can reduce pulsations of thrust caused by end effect. In particular, in the case where the stator includes permanent magnets having the same poles and salient poles which alternate with the permanent magnets, the number of permanent magnets used can be reduced to half of that of a conventional linear electric machine.