Segmented Rotor Transverse Flux Machine for Steer-by-Wire
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Solution Overview
Problem
Existing steer-by-wire systems for vehicles lack an efficient and cost-effective handwheel actuator that can provide the necessary torque and feedback to the driver, especially in direct drive applications where high torque and low speed are required.
Innovation Solution
The use of a transverse flux machine (TFM) as a handwheel actuator in steer-by-wire systems, which features a rotor assembly with axially stacked segments and a stator assembly with transverse flux cores directing magnetic flux in both axial and radial directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional actuators are used in steer-by-wire systems, then the system can provide steering assist, but the handwheel actuator cannot provide sufficient torque density for direct drive applications
Solution Approach 1:
The rotor assembly is divided into multiple axially stacked segments, each containing rotor cores and permanent magnets. This segmentation allows for increased torque density while maintaining manufacturing simplicity, as each segment can be independently manufactured and then assembled. The segmented structure enables better utilization of magnetic materials and optimizes the magnetic flux path.
Solution Approach 2:
The patent transitions from conventional radial flux machines to transverse flux machines, fundamentally changing the dimensionality of magnetic flux flow. The flux now travels in both axial and radial directions simultaneously, creating a three-dimensional magnetic circuit that significantly increases torque density without proportionally increasing machine size or complexity.
2Force
If high torque is achieved through conventional means, then the actuator can provide sufficient force, but torque ripple increases
Solution Approach 1:
The rotor is segmented into multiple identical or near-identical sections stacked axially. This segmentation creates multiple parallel magnetic circuits that operate simultaneously, averaging out the torque fluctuations and significantly reducing torque ripple while maintaining high total torque output.
Solution Approach 2:
Multiple rotor segments are combined axially to work together as a unified structure. The combined effect of multiple segments produces smooth, continuous torque with reduced ripple, as the individual torque pulses from each segment overlap and reinforce each other rather than creating gaps.
3Power
If complex actuator designs are used to achieve high torque density, then direct drive capability is improved, but manufacturing cost and complexity increase
Solution Approach 1:
By segmenting the rotor into standardized modules, the manufacturing process is simplified. Each segment can be manufactured using the same processes and then assembled through straightforward stacking, reducing tooling costs and enabling volume production while achieving high torque density.
Solution Approach 2:
The transverse flux machine design serves multiple functions within a single actuator structure: it provides high torque density for direct drive, inherently reduces torque ripple through its segmented construction, and maintains manufacturing simplicity through modular assembly. This multi-functionality eliminates the need for separate components that would increase complexity.
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 TFM handwheel actuator achieves high torque density and reduced torque ripple, making it suitable for direct drive low-speed operations while simplifying manufacturing and reducing costs.
Implementation Method 1
a stator assembly including a transverse flux core configured to direct a magnetic flux in each of an axial direction and a radial direction toward the rotor assembly
Implementation Method 2
The TFM includes: a rotor assembly configured to rotate about an axis and including a plurality of segments stacked axially, each segment of the plurality of segments includes a plurality of rotor cores and a plurality of permanent magnets
Implementation Method 3
each segment of the plurality of segments includes a plurality of rotor cores and a plurality of permanent magnets
Data Source
AI summary
A transverse flux machine (TFM) includes a rotor assembly configured to rotate about an axis and including a plurality of segments stacked axially. Each segment of the plurality of segments includes a plurality of rotor cores and a plurality of permanent magnets. The TFM also includes a stator assembly including a transverse flux core configured to direct a magnetic flux in each of an axial direction and a radial direction toward the rotor assembly. A steer-by-wire system for a vehicle includes a handwheel actuator coupled to apply a torque to a steering wheel. The handwheel actuator includes a transverse flux machine (TFM) which includes a stator assembly and a rotor assembly configured to rotate about an axis. The rotor assembly includes a plurality of segments stacked axially. Each segment of the plurality of segments includes a plurality of rotor cores and a plurality of permanent magnets.