Multi-DOF Electromagnetic Machine Torque and Thermal Design
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Solution Overview
Problem
Current spherical motor designs for multi-degree-of-freedom applications, such as UAVs and robotics, face limitations in torque generation, thermal handling, and complexity in winding configurations, leading to inefficient performance in applications requiring precision actuation.
Innovation Solution
A multi-degree-of-freedom electromagnetic machine design featuring an outer and inner case, stator and rotor with radially extending/stator poles, voice coil winding, and tilt magnets, allowing for improved torque generation, thermal management, and simplified winding configurations, enabling rotation about multiple axes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a spherical motor design with orthogonally placed coils and multi-pole magnets is used, then multi-degree-of-freedom motion is achieved, but torque generation is limited due to large air gap and heavy spherical stator
Solution Approach 1:
The motor is divided into separate functional components: a spherical rotor assembly containing the spherical stator with orthogonally placed coils, and a separate multi-pole magnet assembly. This segmentation allows the heavy spherical stator to be isolated from the rotor, reducing rotor weight and improving torque generation while preserving multi-DOF motion capabilities.
Solution Approach 2:
The invention transitions from a conventional spherical motor configuration to a hybrid design that combines spherical geometry with planar magnetic arrays. The multi-pole magnets are arranged in planar arrays on opposite sides of the spherical rotor, creating a three-dimensional magnetic field structure that enhances torque generation while maintaining spherical motion capabilities.
2Adaptability or versatility
If conventional spherical motor designs are used, then multi-axis rotation is achieved, but winding configurations become complicated and time-consuming
Solution Approach 1:
The winding system is segmented into modular coil assemblies that are pre-configured and then integrated into the spherical rotor. This modular approach simplifies the winding process by allowing standardized coil units to be assembled rather than requiring complex custom windings for each axis, reducing manufacturing time and complexity.
Solution Approach 2:
The spherical stator with orthogonally placed coils serves multiple functions: it generates magnetic fields for all three axes of rotation and provides a unified structure that simplifies the winding configuration. This universal design eliminates the need for separate winding systems for each axis, reducing overall manufacturing complexity.
3Stability of the object's composition
If a metal post is used to hold the coil assembly axially and vertically, then structural support is provided, but the structure becomes heavier
Solution Approach 1:
The heavy metal post support structure is extracted and replaced with magnetic field-based positioning. The spherical stator is held axially and vertically through magnetic forces generated by the coil assemblies and interacting with the multi-pole magnets, eliminating the need for mechanical metal post support and significantly reducing the weight of the moving components.
Solution Approach 2:
The mechanical metal post support system is replaced with a magnetic field-based support system. The coil assemblies and multi-pole magnets create magnetic forces that provide axial and vertical positioning of the spherical stator, substituting mechanical support with electromagnetic forces and reducing overall structure weight.
4Device complexity
If spherical motors are used to replace complicated multi-DOF assemblies, then device complexity is reduced, but thermal handling capabilities deteriorate due to high winding temperatures
Solution Approach 1:
The thermal management system is segmented into dedicated cooling channels integrated with the spherical stator structure. These channels provide direct coolant flow paths to the coil windings, efficiently removing heat generated during operation while maintaining the simplified spherical motor design.
Solution Approach 2:
A coolant intermediary is introduced to transfer heat from the winding assemblies. The cooling channels carry coolant through close proximity to the coils, acting as a thermal intermediary that efficiently removes heat from the windings without adding mechanical complexity to the spherical motor structure.
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 enhances torque output, thermal efficiency, and reduces complexity, resulting in improved performance and stability for precision actuation systems.
Implementation Method 1
The stator windings are wound around the stator poles and are operable, upon being energized, to generate a magnetic field
Implementation Method 2
The voice coil winding is fixedly coupled to the inner surface of the outer case. The tilt magnet is fixedly coupled to the outer surface of the inner case
Data Source
AI summary
A multi degree-of-freedom electromagnetic machine includes an outer case, an inner case, a stator, stator windings, a voice coil winding, a tilt magnet, a rotor, and rotor magnets. The inner case is disposed within an inner cavity of the outer case and is mounted to rotate relative to the outer case about one or more rotational axes. The stator is fixedly mounted within the inner case, and the stator windings are wound thereon. The voice coil winding is fixedly coupled to either the inner surface of the outer case or the outer surface of the inner case. The tilt magnet is fixedly coupled to either the outer surface of the inner case or the inner surface of the outer case. The rotor is rotationally mounted within the inner case and is operable to rotate, relative to the stator, about a rotational axis.