Dual-Airgap Motor Layout for Higher Torque Density
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Solution Overview
Problem
Current motor and generator designs face challenges in achieving high efficiency, power density, and reduced size while maintaining low cost, particularly in variable speed systems, due to complex design and control requirements for multiple airgap configurations.
Innovation Solution
The design incorporates a stator with multiple slots and teeth, featuring dual rotors and airgaps, along with advanced winding arrangements and power converters to optimize torque production and efficiency, allowing for dynamic reconfiguration of the number of poles and phases through software-defined control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple airgaps are implemented in motor/generator design, then power density and torque production are improved, but design and control complexity increases significantly
Solution Approach 1:
The motor is divided into multiple independent airgap regions (first airgap between stator inner surface and first rotor, second airgap between stator outer surface and second rotor), each functioning as a separate submotor. This segmentation allows each airgap to contribute independently to torque production, increasing overall power density while maintaining manageable control through modular architecture
Solution Approach 2:
The dual-rotor configuration places one rotor inside another, with the first rotor positioned within the stator inner surface and the second rotor positioned outside the stator outer surface. This nested arrangement maximizes the use of available space within the motor housing, allowing both airgaps to be utilized simultaneously without proportionally increasing overall motor size, thereby improving power density
2Force
If multiple rotors and airgaps are used, then torque density is enhanced, but system size and manufacturing cost increase
Solution Approach 1:
The stator structure serves multiple functions simultaneously: it provides the magnetic circuit for both airgaps, supports the winding conductors, and contains both the inner and outer rotor assemblies. This multi-functionality reduces the need for additional separate components, simplifying manufacturing and reducing costs despite the enhanced torque density achieved through dual airgaps
Solution Approach 2:
The windings are arranged such that first conductors are positioned in first slots facing the first airgap and second conductors are positioned in second slots facing the second airgap, with both sets of conductors belonging to the same winding structure. This merging of the winding system allows a single electrical input to drive both airgaps simultaneously, reducing the need for separate control systems and reducing overall manufacturing complexity and cost
3Loss of energy
If dual rotor configuration is implemented, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The magnetic flux paths through both airgaps are continuously active during motor operation, with the windings generating rotating magnetic fields that simultaneously interact with both rotors. This continuous utilization of both airgaps ensures that the structural complexity of the dual-rotor configuration is continuously justified by energy conversion in both paths, improving overall energy efficiency without idle components
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 enhances power and torque density, improves energy efficiency, and reduces system size and cost, enabling better performance across a wide range of operating conditions, including in complex applications like electric vehicles.
Implementation Method 1
a plurality of windings is located between the inner surface and the outer surface, each of the plurality of windings comprising a plurality of first conductors located in a first slot and a plurality of second conductors located in a second slot adjacent to the first slot
Implementation Method 2
the plurality of first conductors, the first airgap, and the first rotor form a first submotor, and the plurality of second conductors, the second airgap, and the second rotor form a second submotor
Implementation Method 3
a plurality of rotors magnetically coupled to the stator, wherein a first rotor of the plurality of rotors faces the inner surface of the stator and a second rotor of the plurality of rotors faces the outer surface of the stator
Data Source
AI summary
An apparatus includes a stator with an inner surface and an outer surface, a plurality of rotors magnetically coupled to the stator, wherein a first rotor faces the inner surface of the stator and a second rotor faces the outer surface of the stator, and a first airgap between the inner surface of the stator and the first rotor, and a second airgap between the outer surface of the stator and the second rotor, wherein first conductors, the first airgap, and the first rotor form a first submotor, and second conductors, the second airgap, and the second rotor form a second submotor, and wherein the first submotor and the second submotor are so configured that the first rotor and the second rotor produce mechanical torques in a same direction when currents flow in the plurality of windings in an operation mode.