Linear Motor Cogging Compensation Using Stored Position Force Maps
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Solution Overview
Problem
Existing linear motors suffer from cogging effects due to position-dependent reluctance differences, which disrupt shuttle movement, especially at lower speeds, and current compensation methods increase computational complexity and cost.
Innovation Solution
Determine cogging forces without energizing drive coils, store them in the control unit, and use these forces to compensate for cogging during operation, considering transverse directions and adjacent shuttle interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If drive coils are energized to generate propulsive force, then shuttle movement is achieved, but cogging effects occur due to position-dependent reluctance differences
Solution Approach 1:
The patent determines and stores cogging forces in advance during a calibration phase before actual operation. During operation, these pre-determined cogging forces are used to compensate for position-dependent reluctance differences, eliminating the need to calculate complex magnetic field interactions in real-time and reducing computational complexity
2Object-affected harmful factors
If skewing is applied to drive magnets or teeth to reduce cogging, then cogging forces are reduced, but propulsion forces are also reduced and manufacturing complexity increases
Solution Approach 1:
The patent changes the parameter being compensated from the physical geometry of components to the electromagnetic field parameters. By determining cogging forces as a function of position and compensating through control parameters rather than physical skewing, the patent maintains standard manufacturing while achieving cogging reduction
3Measurement precision
If computational methods are used to compensate cogging effects, then movement precision is improved, but computational complexity and cost increase
Solution Approach 1:
The patent performs the computationally intensive determination of cogging forces in advance during a calibration phase. The results are stored and reused during operation, transforming a complex real-time computational problem into a simple lookup and compensation application, thereby reducing operational computational complexity while maintaining precision
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
Simplifies cogging compensation by reducing magnetic interference, improving shuttle movement efficiency, and minimizing computational complexity.
Implementation Method 1
the drive coils in the region of the at least one shuttle are energized under control of a control unit to produce an electromagnetic field that interacts with a drive magnetic field produced by the drive magnets in order to generate a propulsive force
Implementation Method 2
so called cogging effects may occur. The reason for such cogging effects are position dependent reluctance (magnetic resistance) differences
Data Source
AI summary
A linear motor and method for operating a linear motor are disclosed. The linear motor comprises a stator and a shuttle. Cogging forces in at least one direction of movement of the shuttle along the stator are determined as a function of the relative position of the shuttle with respect to the stator in the at least one direction of movement and while the drive coils in the region of the shuttle are non-energized. The determined cogging forces are stored in a control unit. The stored cogging forces are used by the control unit to compensate the cogging forces during operation of the linear motor in dependence of the relative position between a shuttle for which the cogging forces are compensated and the stator.