Magnetic Field Sensor for Absolute Position Detection
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Solution Overview
Problem
Existing magnetic field sensors used in electric motor drive applications, such as those in electrical automobiles, do not provide accurate enough determination of the rotational angle or position of an electric motor shaft, leading to inaccuracies in rotation direction and speed measurements.
Innovation Solution
A magnetic field sensor system that includes multiple magnetic field sensing elements disposed proximate to different portions of a target object with varying features, generating distinct magnetic field signals to determine absolute position through a position detection module and output format module, which processes these signals to provide precise rotational angle and position information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a gear tooth sensor is used to detect rotation of an electric motor shaft, then speed and direction information can be obtained, but the accuracy of rotational angle and position determination is insufficient
Solution Approach 1:
The target object is divided into multiple portions, each with a distinct quantity of features. This segmentation allows the sensor to detect different portions and use the varying feature quantities to determine absolute position and rotational angle with higher accuracy, resolving the limitation of gear tooth sensors that can only provide relative position information.
Solution Approach 2:
Different portions of the target object are given different local qualities by assigning different quantities of features to each portion. This enables the magnetic field sensor to distinguish between different portions and calculate absolute rotational angle based on the specific feature quantity detected, thereby improving both measurement precision and reliability.
2Measurement precision
If multiple magnetic field sensing elements are used to sense position of an electric motor shaft, then position information can be obtained, but the accuracy of angle of rotation and direction of rotation determination remains insufficient
Solution Approach 1:
The target object is segmented into multiple portions with different feature quantities, and multiple magnetic field sensing elements are positioned to detect different portions. This allows the system to not only determine position but also calculate rotational direction and absolute angle by comparing signals from different sensing elements, thereby improving both precision and reliability.
Solution Approach 2:
The system uses feedback from multiple magnetic field sensing elements detecting different portions of the target object. By processing the signals from these elements and comparing them against the known feature quantities of different portions, the system can accurately determine absolute position, rotational angle, and direction, resolving the accuracy limitations of conventional approaches.
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 enhances the accuracy of rotational angle and position detection of a target object, improving the precision of electric motor control by providing reliable position, speed, and direction data, addressing the limitations of existing sensors in electric motor drive applications.
Implementation Method 1
Magnetic field sensors provide an electrical signal representative of a sensed magnetic field
Implementation Method 2
Various types of magnetic field sensing elements are known, including Hall Effect elements
Implementation Method 3
Various types of magnetic field sensing elements are known, including Hall Effect elements and magnetoresistance elements
Implementation Method 4
the magnetic field generated by the magnet and sensed by the magnetic field sensor varies in accordance with a shape or profile of the moving ferromagnetic object
Data Source
AI summary
A magnetic field sensor for sensing an absolute position of a target object can include one or more magnetic field sensing elements disposed proximate to a mechanical intersection of first and second portions of a target object, wherein the one or more magnetic field sensing elements are operable to generate a first magnetic field signal responsive to the movement of both the first and second portions. The magnetic field sensor can also include a position detection module operable to use the first magnetic field signal to generate a position value indicative of the absolute position. The magnetic field sensor can also include an output format module coupled to receive the position value and to generate an output signal from the magnetic field sensor indicative of the absolute position.