Position Detector for Moving Magnet Linear Motor
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Solution Overview
Problem
Conventional position detection methods in moving magnet type linear motors, such as those used in passenger elevators, face challenges in achieving high accuracy and reliability due to communication breakdowns and complex wiring requirements, especially in multi-car elevators.
Innovation Solution
A position detector system that uses a magnetic body fixed to the mover, where the position is determined by measuring changes in mutual inductance between coils caused by a magnetic field generated by applying voltage to selected coils, allowing for accurate position detection without the need for communication wires between the stator and mover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If wireless communication means is employed to transmit position detection signal from mover to stator, then communication complexity is reduced, but communication reliability deteriorates due to potential breakdowns during transmission
Solution Approach 1:
Instead of transmitting the position detection signal from the mover to the stator as in conventional systems, the present invention inverts the approach by detecting the position signal on the stator side through mutual inductance measurement between coils. This eliminates the need for communication means between mover and stator, resolving the contradiction between communication complexity and transmission reliability.
2Reliability
If wired communication means is employed to transmit position detection signal, then communication reliability is improved, but device complexity increases due to communication wire placement especially in multi-car elevators
Solution Approach 1:
The invention extracts and eliminates the communication wire component from the system by implementing position detection on the stator side through mutual inductance measurement. This removes the source of complexity associated with wire placement in towers, especially in multi-car elevator configurations, while maintaining reliable position detection.
3Measurement precision
If linear encoder with sensor on mover is used for position detection, then position detection accuracy is improved, but device complexity increases due to controller and communication means requirements
Solution Approach 1:
The invention merges the position detection function directly into the stator coil system by utilizing mutual inductance measurement. Instead of separate sensors on the mover and a dedicated controller, the position detection is integrated into the existing stator coil structure, reducing device complexity while maintaining high measurement precision through the magnetic body's position-dependent inductance changes.
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
Enables high-accuracy position detection of the mover relative to the stator, reducing the complexity of wiring and communication issues, and improving the reliability of position sensing in moving magnet type linear motors.
Implementation Method 1
a current or a voltage induced in a coil adjacent to the selected coil is measured
Data Source
AI summary
In a moving magnet type linear motor including a stator with a plurality of coils placed in one direction and a mover with a permanent magnet opposed to the stator, a position detector detects the position of the mover. The position detector includes a magnetic body fixed to the mover. One or two or more coils are selected and a voltage is applied to the selected coil while a current or a voltage induced in a coil adjacent to the selected coil is measured, and the position of the magnetic body that changes in response to the position of the mover is determined based on the measured current or the measured voltage.