Halbach Array Position Sensor for LSM Immunity
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Solution Overview
Problem
Existing position sensing systems for linear synchronous motors, such as those using optical methods or radio signals, are prone to environmental interference like dirt and snow, and electrical interference from high-current drive pulses, which affects their accuracy and reliability.
Innovation Solution
A position sensor system utilizing permanent magnet material and load cells housed in a weatherproof container, immersed in the magnetic fields of Halbach arrays, which generates a measurable electrical signal due to the force exerted by the magnetic fields, and is shielded from environmental and electrical interference, allowing precise control of the motor's windings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical position sensing systems are used, then position detection capability is provided, but the system is affected by dirt and snow on the banded strip
Solution Approach 1:
The patent replaces the optical sensing system with a magnetic sensing system. Instead of using optical components (lasers, photocells, banded strips), the invention uses magnetic sensors to detect the position of the Halbach array by sensing the magnetic field gradient. This substitution eliminates the problem of optical components being affected by dirt and snow, as magnetic fields are not blocked by these environmental factors.
Solution Approach 2:
The patent changes the detection parameter from optical reflection (optical system) to magnetic field gradient (magnetic system). By measuring the gradient of the magnetic field produced by the Halbach array rather than detecting reflected light, the system achieves position detection that is immune to environmental contamination by dirt and snow.
2Measurement precision
If radio signal systems are used, then position determination is achieved, but the system is subject to interference from high-current drive pulses
Solution Approach 1:
The patent replaces the radio signal-based position determination system with a magnetic field-based sensing system. Instead of using radio transmitters and receivers that are vulnerable to electrical interference from high-current drive pulses, the invention uses magnetic sensors that directly detect the magnetic field gradient produced by the Halbach array, providing immunity to electrical interference.
3Reliability
If sensors are placed in gaps in LSM windings, then magnetic field interference from windings is avoided, but the sensor housing must be weatherproof to protect from environmental conditions
Solution Approach 1:
The patent segments the sensor system into a protected housing unit that contains the magnetic sensors and signal processing electronics. This encapsulation allows the sensors to be placed in the optimal location (gaps in LSM windings) while the weatherproof housing protects the internal components from environmental conditions, separating the functional requirements from the environmental protection requirements.
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 system provides accurate and reliable phase-locked acceleration and propulsion by sensing the position of Halbach arrays, unaffected by environmental conditions or electrical noise, enabling precise control of current pulses in the motor windings, even in harsh environments.
Implementation Method 1
the net longitudinal force on the magnet is proportional to the first derivative of the transverse magnetic field at the sensor
Implementation Method 2
immersed in the magnetic fields produced by Halbach arrays
Data Source
AI summary
A position sensor suitable for use in linear synchronous motor (LSM) drive systems employing Halbach arrays to create their magnetic fields is described. The system has several advantages over previously employed ones, especially in its simplicity and its freedom from being affected by weather conditions, accumulated dirt, or electrical interference from the LSM system itself.