Brushless DC Motor Hall Sensor Positioning via Convex Support Ring
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Solution Overview
Problem
Conventional Hall-effect brushless DC motors face challenges with high manufacturing costs and inaccurate position measurement due to the close proximity of the Hall element to the magnetic ring, which is affected by coil winding currents and has a complex mounting structure.
Innovation Solution
A Hall-effect brushless DC motor design featuring a convex support ring spaced apart from the permanent magnet on the rotor's end surface, allowing the magnetic ring to be mounted with minimal interference, and the Hall element positioned outside the coil winding for improved accuracy and simplified mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Hall element is mounted inside the coil winding to measure rotor position, then the position measurement can be implemented, but the coil winding current interferes with the magnetic ring's secondary magnetic field causing measurement inaccuracy
Solution Approach 1:
The Hall element is extracted from the interior of the coil winding and relocated to the exterior. This removes the Hall element from the harmful electromagnetic environment created by the coil current, eliminating the interference that caused measurement inaccuracies while preserving the position sensing function.
Solution Approach 2:
A magnetic ring is introduced as an intermediary component between the rotor and the Hall element. The magnetic ring generates a secondary magnetic field that carries the rotor position information to the Hall element, enabling accurate measurement without requiring the Hall element to be positioned where it would be directly exposed to harmful coil currents.
2Measurement precision
If the Hall element is positioned close to the magnetic ring for accurate measurement, then position sensing is improved, but the mounting structure becomes complicated and costs increase
Solution Approach 1:
The mounting structure merges multiple functions into integrated components. The stator core incorporates both the coil winding mounting slots and the Hall element mounting cavity, while the magnetic ring serves dual purposes as both a structural support and a magnetic field generator. This integration simplifies the overall mounting structure and reduces component count.
Solution Approach 2:
Components are designed with multi-functionality to reduce overall system complexity. The magnetic ring provides both structural support for positioning the Hall element and generates the secondary magnetic field for sensing. The stator core structure serves both mechanical support and magnetic circuit functions, eliminating the need for separate mounting structures.
3Force
If a long magnetic tile is used to generate the main magnetic field, then the magnetic field strength is sufficient, but the manufacturing cost increases
Solution Approach 1:
Instead of relying solely on a long magnetic tile to generate the main magnetic field, the system creates a copied or replicated magnetic field through the magnetic ring. The magnetic ring generates a secondary magnetic field that replicates the necessary magnetic flux patterns, allowing the use of a shorter, less expensive magnetic tile while achieving sufficient magnetic field strength for operation.
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 design enhances measurement accuracy, reduces costs, and simplifies the structure while minimizing vibration noise, resulting in a more efficient and cost-effective Hall-effect brushless DC motor.
Implementation Method 1
Conventional Hall-effect brushless DC Motors (BLDC Motors) include a stator on which a Hall plate is usually disposed to directly induce a main magnetic field and feed back the position signal of the rotor
Implementation Method 2
the stator assembly is mounted in the casing and comprises a stator core, a coil winding, and an end insulation plate; the rotor assembly comprises a rotor core and a permanent magnet
Data Source
AI summary
A brushless DC motor including a casing, a stator assembly, a rotor assembly, a magnetic ring, and a circuit board with a Hall element. The stator assembly mounted in the casing and includes a stator core, a coil winding, and an end insulation plate. The rotor assembly includes a rotor core and a permanent magnet, and the end surface of the rotor core is coupled to a magnetic ring support. A convex support ring spaced apart from the permanent magnet is mounted on the edge of the magnetic ring support. The top of the convex support ring is sheathed with the magnetic ring and the Hall element extending out of the circuit board is located on the side of the magnetic ring. The motor minimizes the interference of the magnetic tile and improves measuring accuracy of the Hall element, all while having a simple structure, convenient mounting, and low costs.