Magnetic Sensor Position Estimation for Dust-Resistant Motor Control
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Solution Overview
Problem
Existing position detection systems for motors, such as those using optical encoders, are susceptible to environmental influences like dust particles and require larger motor sizes to accommodate encoders, leading to precision issues and inefficiencies.
Innovation Solution
A method and device utilizing N magnetic sensors displaced in phase by 360 degrees/N to detect the position of a mover, where N is an integer of 3 or more, which generates corrected detection signals to estimate the position through crossing and subdivision detection, eliminating the need for environmental susceptibility and reducing motor size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical encoders are used for position detection, then position detection capability is provided, but the system becomes susceptible to environmental influences like dust particles and the motor size increases
Solution Approach 1:
The patent replaces optical encoders with magnetic sensors that detect magnetic fields generated by the motor's rotor. This substitution eliminates the need for optical components that are susceptible to dust and environmental factors, while maintaining position detection capability through magnetic field sensing.
Solution Approach 2:
The invention extracts the position detection function from the optical encoder system and implements it through magnetic sensors integrated into the motor structure. This removes the vulnerable optical components while preserving the essential position measurement capability.
2Measurement precision
If optical encoders are used for position detection, then position detection capability is provided, but the motor size increases to accommodate the encoder
Solution Approach 1:
The patent merges the position detection function directly into the motor structure by using the motor's own magnetic field for sensing. The magnetic sensors are integrated with the motor components, eliminating the need for separate optical encoder assemblies and reducing overall motor size.
Solution Approach 2:
The motor's magnetic field serves dual purposes: generating motor torque and providing position detection signals. This multi-functionality eliminates the need for separate detection components, thereby reducing motor size while maintaining position detection precision.
3Object-affected harmful factors
If N magnetic sensors are used with phase displacement for position estimation, then environmental resistance is improved, but device complexity increases
Solution Approach 1:
The patent divides the position detection task among N magnetic sensors that are phase-displaced around the motor. Each sensor provides localized magnetic field information, and the combined data from all sensors enables comprehensive position estimation while maintaining environmental resistance.
Solution Approach 2:
The patent introduces a position estimation unit that processes the signals from multiple magnetic sensors. This intermediary component synthesizes the phase-displaced sensor signals to generate accurate position information, managing the complexity through systematic signal processing.
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 approach provides improved precision in position detection, resistant to environmental factors like dust, and allows for a more compact motor design without the need for high-precision optical encoders.
Implementation Method 1
N (where N is an integer of 3 or more) sensors each detect a magnetic field which is in accordance with a position of a mover and output an electrical signal
Data Source
AI summary
A method of position estimation including: a signal detection step in which N (where N is an integer of 3 or more) sensors each detect a magnetic field which is in accordance with a position of a mover and output a detection signal as an electrical signal, the detection signals being displaced in phase by an angle obtained by dividing 360 degrees by N; a crossing detection step in which a crossing detection section sequentially detects a crossing at which each detection signal having been output through the signal detection step crosses another; a subdivision detection step in which a subdivision detection section detects a portion of the detection signal that connects from a crossing to another crossing which is adjacent to that crossing, as one or more subdivision signals; and a line segment joining step in which a line segment joining section sequentially joins the subdivision signals and estimates the position of the mover based on the plural subdivision signals having been joined, to generate an estimated position value signal.