Linear Motor Magnetic Pole Position Detection via Pulse Energization
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Solution Overview
Problem
Linear motors face challenges in accurately detecting the magnetic pole position, especially when the mover is shifted by 180° or under external forces, leading to difficulties in generating thrust and controlling movement.
Innovation Solution
A control device and method that estimate the magnetic pole position through pulse energization, refine the estimation by changing the pole position in small increments, and use direct current excitation to determine the accurate position by matching movement increments, allowing for precise pole position detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct current excitation is applied to pull the mover to the magnetic pole position, then the mover can be positioned accurately under normal conditions, but the method fails when the mover is shifted by 180° or under external forces
Solution Approach 1:
The patent applies dynamics by switching from static direct current excitation to dynamic pulse energization. The control device performs pulse energization in multiple directions to dynamically test mover response, enabling the system to adapt to various initial positions and external force conditions. This dynamic approach allows the system to identify the correct magnetic pole position even when traditional static methods fail.
Solution Approach 2:
The patent implements feedback by monitoring the mover's movement direction and distance in response to pulse energization. The control device adjusts subsequent energization based on this feedback, refining the estimated magnetic pole position iteratively. This feedback mechanism enables accurate position detection under adverse conditions by continuously adapting to the actual mover state.
2Reliability
If pulse energization is performed to estimate magnetic pole position, then the system can handle 180° shifts and external forces, but the process becomes more complex compared to simple direct current excitation
Solution Approach 1:
The patent applies segmentation by dividing the magnetic pole position detection process into distinct stages: initial estimation through pulse energization in multiple directions, refinement of the estimated position, and final verification. This segmented approach breaks down the complex problem into manageable steps, making the control process more systematic and easier to implement despite the increased complexity compared to simple direct current excitation.
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
Improves the accuracy of magnetic pole position detection, enabling better control of thrust generation and movement in linear motors, even under external forces or initial misalignments.
Implementation Method 1
When a linear motor is not energized according to a relative positional relationship (magnetic pole position) between a plurality of coils provided in any one of a mover and a stator and a driving magnet provided in the other of the mover and a stator, a thrust according to a thrust constant of the linear motor cannot be generated.
Implementation Method 2
when the linear motor starts up, a current corresponding to a predetermined magnetic pole position is applied to the linear motor for a certain time and the mover is pulled to the magnetic pole position (direct current excitation)
Data Source
AI summary
A control device for linear motor where a range in which the current magnetic pole position of the linear motor exists is refined using the pulse energization with a suppressed amount of movement of the mover, direct current excitation is performed while changing the refined estimated magnetic pole position by a second amount of change smaller than a first amount of change used for refinement of the estimated magnetic pole position during pulse energization, and it is determined that the estimated magnetic pole position matches the current magnetic pole position of the linear motor when the amount of movement of the mover acquired each time the estimated magnetic pole position is changed matches the amount of movement of the second amount of change.