Double Stator Permanent Magnet Machine Torque Optimization
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Solution Overview
Problem
Conventional switched reluctance machines suffer from undesirable vibrations and high manufacturing costs due to inefficient use of rare earth permanent magnets, limiting their industrial applicability and torque density.
Innovation Solution
A double stator permanent magnet machine design with an inner and outer stator, a rotor with segments of rare earth magnets, and strategically placed windings to optimize magnetic flux distribution, allowing for a higher proportion of electromagnetic forces to contribute to motion while minimizing magnet material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional switched reluctance machines are used, then manufacturing cost is low and structure is robust, but electromagnetic forces create undesirable vibrations and limited industrial applicability
Solution Approach 1:
The machine is divided into two independent stators (inner and outer) that can be controlled separately, allowing independent optimization of torque production and vibration reduction for each stator-rotor interface
Solution Approach 2:
The patent changes the magnetic circuit parameters by introducing permanent magnets in the rotor and using differential winding configurations in the two stators, transforming the force distribution to reduce harmful vibrations while maintaining manufacturing feasibility
2Power
If surface mount permanent magnet synchronous machines are used, then torque density is higher, but rare earth permanent magnet material is expensive and ineffective placement results in high cost and wasteful use
Solution Approach 1:
Permanent magnets are placed only in specific rotor segments where they are most effective for torque production, rather than uniformly distributing them throughout the rotor, thereby reducing total magnet material while maintaining high torque density
Solution Approach 2:
The rotor segments with permanent magnets serve multiple functions: they generate reaction torque through magnetic interaction with stator windings and also contribute to reluctance torque, maximizing the utility of each magnet element
3Use of energy by moving object
If Lipo et al. motor design is used, then permanent magnet excitation is provided, but significant amount of permanent magnet material is required making manufacture expensive
Solution Approach 1:
The rotor is segmented with permanent magnets placed only in specific segments rather than the entire rotor circumference, reducing the total quantity of permanent magnet material while maintaining effective magnetic excitation for torque production
Solution Approach 2:
The patent introduces a dual-stator configuration (inner and outer stators) that creates additional magnetic interaction pathways, allowing reduced magnet material in the rotor to still provide sufficient excitation through enhanced flux paths
4Use of energy by moving object
If Lipo et al. motor design is used, then permanent magnet excitation is provided, but electromagnetic forces contributing to rotational motion are limited
Solution Approach 1:
The dual stator configuration with segmented rotor allows independent control of inner and outer stator windings, enabling optimized current distribution that maximizes the proportion of electromagnetic forces contributing to useful rotational motion
Solution Approach 2:
The patent optimizes magnetic circuit parameters including air gap dimensions, pole arc ratios, and winding distributions to enhance the effectiveness of permanent magnet excitation in generating torque, thereby improving productivity
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 a torque ratio of at least 1:3, reducing manufacturing costs and enhancing power density by effectively utilizing magnetic forces for motion, with the ability to operate as both a motor and generator.
Implementation Method 1
A set of phases, each phase including a subset of the set of inner stator windings and a subset of the set of outer stator windings selectively energize the set of phases with a current to rotate the rotor with respect to the inner stator and the outer stator
Implementation Method 2
strategically placed windings to optimize magnetic flux distribution, allowing for a higher proportion of electromagnetic forces to contribute to motion
Data Source
AI summary
A double stator permanent magnet machine includes an inner stator having a back iron and a set of inner stator poles connected to the back iron, a rotor having a shaft and a set of segments, each segment having a permanent magnet, adjacent the inner stator and rotatively coupled to the inner stator, an outer stator having a set outer stator poles, adjacent the rotor and rotatively coupled to the rotor, a set of inner windings disposed between each of the inner stator poles, and a set of outer windings disposed between each of the outer stator poles.