Linear Electromagnetic Motor Coil Layout for End-Effect Ripple
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Solution Overview
Problem
Existing linear motors with Halbach arrays require permanent magnets with different magnetization directions and widths to suppress thrust ripple caused by the end effect, which complicates the design and increases manufacturing complexity.
Innovation Solution
An electromagnetic device with a field system section featuring permanent magnets arrayed such that magnetization directions change sequentially by a specific angle, combined with armature coils of the same phase receiving the same current, effectively suppressing thrust ripple by connecting coils of the same phase in series to manage magnetic flux distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If permanent magnets with different magnetization directions and widths are used in a Halbach array, then thrust ripple caused by end effect is suppressed, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies local quality by configuring permanent magnets with specific magnetization directions only at the end portions of the field poles, while the central portions use different magnetization directions. This localized differentiation suppresses end effect without requiring all magnets to have complex configurations, thereby reducing overall device complexity while maintaining thrust ripple suppression.
Solution Approach 2:
The field poles are segmented into end portions and central portions with different magnetization configurations. The end portions use magnets with specific magnetization directions to counteract end effect, while the central portions use standard Halbach array magnets. This segmentation allows targeted suppression of thrust ripple without complicating the entire magnet array.
2Reliability
If permanent magnets with different widths are used to suppress end effect, then thrust ripple is reduced, but manufacturing precision requirements increase
Solution Approach 1:
Instead of requiring all permanent magnets to have different widths, the patent applies local quality by using uniform width magnets in the central portions and only differentiating the end portions' magnetization directions. This approach maintains thrust ripple suppression while eliminating the need for precise width variations across all magnets, thereby reducing manufacturing precision requirements.
3Reliability
If complex magnetization patterns are used in all permanent magnets, then end effect is suppressed, but ease of manufacture decreases
Solution Approach 1:
The patent segments the field poles into end portions and central portions, applying complex magnetization patterns only to the end portions where they are most needed for suppressing end effect. The central portions use simpler, standard Halbach array magnetization. This segmentation maintains end effect suppression while significantly improving ease of manufacture by limiting complex configurations to specific locations.
Solution Approach 2:
Complex magnetization patterns are applied locally only at the end portions of field poles rather than uniformly across all magnets. This localized approach suppresses end effect where it occurs most severely while maintaining simple, easy-to-manufacture magnet configurations in the central portions, thereby improving overall ease of manufacture.
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 solution effectively suppresses thrust ripple caused by the end effect, ensuring stable and efficient operation of the electromagnetic device by maintaining consistent current flow in armature coils, thereby reducing design complexity and enhancing performance.
Implementation Method 1
a plurality of permanent magnets are arrayed on a moving body moved relatively in a length direction of an elongated fixed body, the plurality of permanent magnets being arrayed such that a magnetization direction is changed in sequence each time by an angle resulting from dividing one cycle of electric angles corresponding to one cycle of magnetic poles by a division number n
Implementation Method 2
an armature section provided to the fixed body, the armature section including a plurality of sets of armature coils that are arrayed in the length direction of the fixed body within a movement range of the moving body with one set being a number of phases worth of armature coils, and that are fed with power such that the same current is flowed in each of the armature coils of the same phase
Data Source
AI summary
In an electromagnetic device, a field system section, including plural permanent magnets arrayed such that a magnetization direction is changed in sequence each time by a setting angle θ arrayed to give an array length that is a natural number of times a length of one cycle of magnetic poles, is disposed facing an armature section capable of relative movement. In the armature section, coils of each phase are arrayed in sequence, and are connected such that similar current is flowed in each of the coils of the same phase. In the electromagnetic device, even if a change in a distribution of magnetic flux linking with coils occurs at an end portion along the movement direction of the field system section, an end effect in which this change appears in some coils can be suppressed, enabling thrust ripple caused by the end effect to be effectively suppressed.