Linear Motor Position Detection via Inductance Changes
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Solution Overview
Problem
Linear-motor-based systems face high technical and software outlay for position sensing, leading to low positional accuracy, speed accuracy, and dynamics due to the need for extensive sensor configuration and cabling in multi-carrier systems.
Innovation Solution
A method utilizing a secondary-part winding on the secondary part to induce a secondary current at a test frequency, causing a change in the inductance of primary-part coils, allowing for the measurement of relative position without position sensors, by energizing primary-part coils with a primary current at a test frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position sensors are fitted to carriers in multi-carrier systems, then positional accuracy and speed accuracy are improved, but device complexity and technical outlay increase due to sensors, cabling, and software configuration requirements
Solution Approach 1:
The system uses the existing primary-part coils to generate test frequencies that induce secondary currents in the secondary-part windings, allowing the system to self-diagnose carrier positions without external sensors. The primary-part coils serve dual purposes: driving the carriers and detecting their positions through inductance changes.
Solution Approach 2:
Physical position sensors and their mechanical mounting structures are replaced with an electromagnetic field-based detection method. The system measures carrier positions by detecting changes in electrical inductance of the primary-part coils caused by induced secondary currents, substituting mechanical sensing with electrical measurement.
2Measurement precision
If position sensors and corresponding cabling are fitted to carriers, then measurement precision is improved, but device complexity and software outlay increase due to sensor evaluation system configuration
Solution Approach 1:
The primary-part coils perform multiple functions: they generate the traveling magnetic field for driving carriers and simultaneously serve as detection coils for position measurement by measuring their inductance changes. This eliminates the need for separate sensor evaluation software and integrates positioning functionality into the existing drive system.
Solution Approach 2:
The system automatically determines carrier positions by measuring inductance changes in the primary-part coils, eliminating the need for external sensor evaluation systems. The control unit directly processes the electrical measurements to obtain position information without requiring separate sensor configuration or evaluation software.
3Device complexity
If secondary parts are operated purely in a controlled manner without position sensors, then device complexity is reduced, but manufacturing precision deteriorates with low positional accuracy, speed accuracy, and dynamics
Solution Approach 1:
Physical position sensors are replaced with an electrical measurement method that detects carrier positions through inductance changes of the primary-part coils. This substitution maintains high positional accuracy while avoiding the complexity of mechanical sensor systems.
Solution Approach 2:
The system measures carrier positions by detecting changes in the electrical parameter (inductance) of the primary-part coils rather than using mechanical position sensors. By monitoring inductance variations caused by induced secondary currents, the system achieves precise position detection through electrical parameter measurement.
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 precise positioning of secondary parts with increased accuracy and dynamics, reducing the need for additional sensors and cabling, and allowing for sensorless regulation of linear-motor-based systems.
Implementation Method 1
the at least one primary part can be actuated using a drive current such that a primary-part magnetic field forms to achieve an advance of the secondary part
Implementation Method 2
the secondary part has a magnetic active part for forming a secondary-part magnetic field... with the result that an advancing force is produced
Implementation Method 3
at least one secondary-part winding is provided on the secondary part and induction of a secondary current in the secondary-part winding at a test frequency causes a change in the inductance of a primary-part coil situated in spatial proximity to the secondary part
Implementation Method 4
measured current changes in the current responses indicate the change in the inductance of the respective primary-part coil and a relative position of a secondary part to the respective primary-part coil
Data Source
AI summary
A method for locating a secondary part during use in a linear-motor-based system, wherein at least one primary part includes primary-part coils and is provided in the linear-motor-based system, the secondary part has a magnetic active part and the primary-part coils can be actuated via a drive current to achieve an advance of the secondary part, for locating the secondary part, the at least one primary part is energized via a primary current at a test frequency to induce a secondary current in at least one secondary-part winding provided on the secondary part and respective current responses of the primary-part coils are measured, where measured current changes in the current responses indicate the change in the inductance of the respective primary-part coil and a relative position of a secondary part to the respective primary-part coil.