Staggered Coil Linear Motor Reducing Magnetic Flux Leakage
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Solution Overview
Problem
Current photolithographic linear motors face challenges in achieving high-precision positioning and driving forces due to magnetic flux leakage and inconsistent magnetic flux density distribution, which limits their ability to provide desirable control forces and moments in three degrees of freedom.
Innovation Solution
A linear motor design featuring a magnet unit with symmetrically arranged first and second magnet arrays and a coil unit with staggered coil arrays in the Z-axis direction, generating control forces along the Y-axis and Z-axis directions and a moment about the X-axis, utilizing a Halbach array configuration with prismatic magnets to enhance magnetic flux density and reduce leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional NS magnet arrays and single-layered coil arrays are used, then the motor structure is simple, but magnetic flux leakage occurs and precision positioning is insufficient
Solution Approach 1:
The magnet array is segmented into multiple types (first-type, second-type, third-type magnets) arranged in specific patterns, and the coil array is divided into multiple layers. This segmentation allows optimization of magnetic flux distribution and elimination of leakage while maintaining controllable complexity through modular design.
Solution Approach 2:
The patent employs asymmetric magnet arrangements including Halbach arrays where magnet polarities are asymmetrically distributed to maximize magnetic flux in desired directions while minimizing leakage. The coil layers are also asymmetrically positioned at different heights to optimize force generation and reduce ripple effects.
2Ease of manufacture
If laterally aligned cuboid-shaped magnets are used, then manufacturing is simple, but magnetic flux leakage occurs at the magnetic yoke causing precision control difficulties
Solution Approach 1:
Different regions of the magnet array have different magnet shapes and orientations optimized for their specific functions. For example, magnets at boundaries may have different configurations than those in the center to prevent flux leakage, while maintaining overall manufacturing feasibility through standardized production techniques.
3Productivity
If high-speed movement capability is increased, then throughput is improved, but high-precision positioning becomes more difficult to achieve
Solution Approach 1:
The motor design incorporates dynamic control capabilities through multi-layer coil arrays that can be independently controlled, allowing the system to adapt to different operational modes. The magnetic field distribution is dynamically adjustable to optimize for either high-speed movement or high-precision positioning as needed.
Solution Approach 2:
The patent enables parameter changes in the magnetic field strength, coil current distribution, and magnet array configuration to optimize performance for different operational requirements. By adjusting these parameters, the system can achieve high-speed movement when throughput is prioritized and high-precision positioning when accuracy is critical.
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 achieves increased vertical and horizontal magnetic fluxes, allowing for higher driving forces in six degrees of freedom, improved precision positioning, and reduced mass, while eliminating torsional moments and magnetic flux leakage.
Implementation Method 1
the coil unit includes a first coil array and a second coil array arranged in a stacked manner in the Z-axis direction and the first and second coil arrays are staggered from each other by a distance of ΔP in the Y-axis direction, and ΔP is so set that when the coil unit is provided with a desired electrical current from a control system, the coil unit generates a first control force along the Y-axis direction, a second control force along the Z-axis direction, and a moment about the X-axis direction
Implementation Method 2
A linear motor design featuring a magnet unit with symmetrically arranged first and second magnet arrays and a coil unit with staggered coil arrays in the Z-axis direction, generating control forces along the Y-axis and Z-axis directions and a moment about the X-axis, utilizing a Halbach array configuration with prismatic magnets to enhance magnetic flux density and reduce leakage
Implementation Method 3
utilizing a Halbach array configuration with prismatic magnets to enhance magnetic flux density and reduce leakage
Data Source
AI summary
A linear motor includes a magnet unit and a coil unit. The magnet unit includes two magnet arrays oppositely parallel and symmetrically located on a magnetic yoke: a first and a second magnet array. The coil unit is disposed in a magnetic gap between the two magnet arrays. In a spatial rectangular coordinate system defined by X, Y and Z axes, the coil unit includes a first and a second coil array arranged in a stacked manner in the Z-axis direction and staggered from each other by a distance of ΔP in the Y-axis direction. ΔP satisfies: when a control system charges the coil unit with a desired current, the coil unit generates a control force along the Y-axis direction, another control force along the Z-axis direction, and a moment about the X-axis direction, which may reduce a magnetic flux leakage and provide higher driving forces, making the linear motor generate required three degrees-of-freedom control force or control torque, and further improve vertical and horizontal magnetic fluxes in the magnet array.