Rotor Flux Passage Layout for Saturation-Resistant SynRM Motors
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Solution Overview
Problem
Magnet-assisted synchronous reluctance motors face challenges with excessive magnetic flux saturation in the rotating direction, affecting performance, and the use of magnets of varying sizes complicates mass production and can weaken reluctance torque.
Innovation Solution
A rotor design featuring a stack of electromagnetic steel plates with through-hole groups, where magnets are placed in some holes and electrically conductive material fills others, with varying magnetic flux passage widths to manage magnetic flux density and maintain self-starting characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If magnets are inserted into magnetic flux barriers to generate magnetic flux torque, then motor efficiency and power coefficient increase, but magnetic flux density becomes excessively saturated in the rotating direction
Solution Approach 1:
The magnetic flux barrier is designed with non-uniform thickness, being thinner at the pole tip side and thicker at the opposite side. This local variation in geometry allows the barrier to effectively control magnetic flux distribution: the thinner region reduces flux saturation at the pole tip where saturation is most problematic, while the thicker region maintains adequate barrier function elsewhere. This resolves the contradiction by optimizing the local structure rather than using a uniform design throughout.
Solution Approach 2:
The invention changes the geometric parameter of the magnetic flux barrier from a uniform thickness to a variable thickness profile. By adjusting the thickness parameter along the circumferential direction, the design optimizes magnetic flux density distribution, preventing excessive saturation while maintaining the torque-enhancing benefits of magnet insertion.
2Object-affected harmful factors
If magnets of different sizes are inserted into magnetic flux barriers to adjust optimal number of usable magnets, then magnetic flux saturation is suppressed, but device complexity increases and mass production becomes difficult
Solution Approach 1:
Instead of varying magnet sizes, the invention uses a uniform magnet design combined with a magnetic flux barrier of non-uniform thickness. The local quality variation is achieved through the barrier geometry rather than magnet dimensions, simplifying manufacturing while maintaining the ability to control flux saturation through the tailored barrier profile.
Solution Approach 2:
The invention changes the parameter being optimized from magnet size to magnetic flux barrier thickness. This parameter substitution maintains the capability to control magnetic flux density and suppress saturation, while using a single magnet size simplifies the manufacturing process and enables easier mass production.
3Power
If larger size magnets are used to improve motor performance, then power coefficient increases, but self-starting characteristic is affected
Solution Approach 1:
The magnetic flux barrier with non-uniform thickness creates localized magnetic flux control that balances the effects of magnet size. The thinner region at the pole tip allows sufficient flux for self-starting, while the overall magnet presence provides the power coefficient enhancement. This local geometric modulation resolves the contradiction between magnet size and self-starting capability.
4Object-affected harmful factors
If rib structure is added to magnetic flux barrier to distribute magnetic flux, then flux distribution improves, but rotor structure is significantly changed and reluctance torque may be weakened
Solution Approach 1:
The invention achieves flux distribution through local variation in the magnetic flux barrier thickness itself, rather than adding separate rib structures. The non-uniform barrier profile naturally guides and distributes magnetic flux along the desired path, achieving the flux distribution benefit while maintaining a simpler rotor structure that preserves reluctance torque characteristics.
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 improves magnetic flux density saturation, enhances reluctance torque, and optimizes motor performance by effectively utilizing magnets while ensuring ease of mass production.
Implementation Method 1
The magnet generates an extra magnetic flux to produce a magnetic flux torque
Implementation Method 2
A magnet is inserted in a magnetic flux barrier for further improving the efficiency of a motor
Implementation Method 3
the magnetic flux significantly increases in the rotating direction of a rotor, so that a magnetic flux density in the rotating direction is excessively saturated
Implementation Method 4
These air gaps cause a difference in reluctance. When an electric current is fed to the motor, the motor produces a reluctance torque owing to the difference in reluctance
Data Source
AI summary
A rotor includes a stack of electromagnetic steel plates each including through-hole groups with through-holes extending through the respective electromagnetic steel plates. In each of the through-hole groups, at least one of the through-holes accommodates a magnet and at least a portion of the through-holes that does not accommodate any magnet is filled with an electrically conductive material. When the rotor is seen axially, at two circumferential sides of a magnetic flux passage that is adjacent to the magnet, a width of the magnetic flux passage adjacent a first side of the magnet is larger than a width of the magnetic flux passage near a second side of the magnet.