Double Air Gap Vernier Machine Ferrite Torque
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Solution Overview
Problem
The increasing cost of neodymium and dysprosium ore has led to a search for topologies that provide good torque density using ferrite magnets, resulting in bulky machines due to lower flux densities compared to rare earth magnet machines, necessitating alternative designs for permanent magnet machines.
Innovation Solution
The vernier permanent magnet machine design, featuring a rotor with multiple permanent magnets mounted as spokes and two stators with offset teeth and windings, synchronizes space harmonics to produce additional torque components, enhancing torque density without increasing machine size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ferrite magnets are used instead of rare earth magnets, then cost is reduced, but flux density decreases resulting in bulky machines
Solution Approach 1:
The patent transitions from a conventional single air gap topology to a double air gap vernier topology, adding a dimensional change in the magnetic circuit path. This allows the machine to achieve higher torque density with ferrite magnets by creating two separate magnetic paths that interact through the rotor, effectively compensating for the lower flux density of ferrite materials without increasing overall machine volume
Solution Approach 2:
The invention combines ferrite magnets with a specific double stator configuration to create a composite magnetic system. By using ferrite magnets in conjunction with the vernier effect produced by two offset stators, the system achieves performance comparable to rare earth magnets while maintaining the cost advantage of ferrite materials
2Quantity of substance
If ferrite magnets are used instead of rare earth magnets, then cost is reduced, but torque density decreases
Solution Approach 1:
The double air gap vernier topology introduces an additional magnetic interaction dimension. The two stators with offset teeth create vernier effects that multiply the torque production capability, allowing ferrite magnets to achieve high torque density through the combined effect of two magnetic paths rather than relying solely on the intrinsic properties of the magnet material
Solution Approach 2:
The patent merges two separate magnetic circuits (one from each stator) into a unified torque production system. The two stators with their respective windings and offset configurations work together synergistically, combining their magnetic fields to produce enhanced torque density that compensates for the lower flux density of ferrite magnets
3Device complexity
If conventional single air gap topology is used, then structure is simpler, but torque density is lower
Solution Approach 1:
The patent adds a second air gap dimension to the conventional single air gap topology. This creates a double air gap structure where two stators interact with the rotor through separate magnetic paths, enabling the system to achieve higher torque density by utilizing two independent magnetic circuits that can be optimized separately while maintaining overall structural coherence
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 achieves higher torque and back-EMF compared to conventional machines, with the potential for more compact and efficient low-speed applications, particularly suitable for motor and generator use with ferrite magnets.
Implementation Method 1
The vernier machine includes, but is not limited to, a rotor, a plurality of permanent magnets mounted as spokes in pole pairs within the rotor, a first stator, a second stator, a first stator winding, and a second stator winding
Implementation Method 2
A first plurality of teeth is offset from a second plurality of teeth by a half slot pitch relative to the rotor
Data Source
AI summary
A vernier machine includes a rotor, permanent magnets mounted as spokes in pole pairs within the rotor, a first stator, a second stator, a first stator winding wound about the first stator to form a number of poles between a first set of terminals, and a second stator winding wound about the second stator to form the number of poles between a second set of terminals. The first stator and the second stator each include slots and teeth. The first stator and the second stator are mounted on opposite sides of the rotor with each separated by an air gap. The teeth of the first stator are offset from the teeth of the second stator by a half slot pitch relative to the rotor. A number of the pole pairs of the rotor is greater than the number of poles of the first stator winding.