Linear Motor Stator Shifting for Uneven Coil Load Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multi-phase linear motors used in lithography apparatuses experience local deterioration and performance reduction due to uneven power loads on coils during acceleration and deceleration, leading to temperature rises and reduced motor life.
Innovation Solution
A control method for a driving apparatus that adjusts the position of the stator with respect to a predetermined range and determines output ratios of coils based on this position, distributing current loads more evenly between coils at acceleration and deceleration points to reduce local deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If multi-phase excitation driving is used to reduce thrust unevenness, then constant thrust is achieved, but power load concentration on single phase coils during acceleration/deceleration causes temperature rise and performance deterioration
Solution Approach 1:
The patent applies dynamics by making the stator position adjustable rather than fixed. The stator can be shifted in the traveling direction to change which coils are positioned at the acceleration point and deceleration point. This dynamic repositioning allows the system to adapt coil usage patterns, distributing power loads more evenly across multiple coils over time and reducing localized deterioration.
Solution Approach 2:
The patent changes the physical parameter of stator position to alter the operational characteristics of the motor. By shifting the stator position, the phase angles and output ratios of individual coils change, allowing different coils to share the burden of acceleration and deceleration forces. This parameter change transforms the fixed load distribution into a variable one that can be optimized for reliability.
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
This method effectively reduces the bias of current loads on coils, thereby minimizing local deterioration and extending the life of the linear motor by distributing power loads more evenly during the driving process.
Implementation Method 1
a multi-phase excitation driving type that utilizes the principle of sin2(x)+cos2(x)=1. When driving the stage, the multi-phase excitation driving type linear motor simultaneously applies, to the coils of two phases whose phase angles of the magnetic flux densities are separated by 90°, currents corresponding to the respective magnetic flux densities
Implementation Method 2
the multi-phase excitation driving type linear motor simultaneously applies, to the coils of two phases whose phase angles of the magnetic flux densities are separated by 90°, currents corresponding to the respective magnetic flux densities (performs two-phase excitation). With this, it is possible to obtain a constant thrust with reduced thrust unevenness.
Data Source
AI summary
The present invention provides a control method of a driving apparatus that repeatedly performs a process of driving a target object in a predetermined range by a linear motor, wherein the linear motor includes a stator in which a plurality of coils are arrayed, and a mover provided with the target object, the control method comprising: changing a position of the stator with respect to the predetermined range at an arbitrary timing; and determining, in accordance with the changed position of the stator, output ratios of the plurality of coils in the process.