BLDC Motor Hall Sensor Positioning for Magnetic Flux Transmission
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Solution Overview
Problem
Conventional BLDC motors often fail to accurately detect the positional information of the rotor due to insufficient transmission of magnetic flux from the permanent magnet to the hall sensor, leading to inaccurate motor control and potential motor stoppage.
Innovation Solution
The BLDC motor design includes a stator with radially extending teeth and a rotor with permanent magnets, where hall sensors are positioned within the height range of the rotor's overhang to detect magnetic field changes, and the central height of the rotor is offset from the stator's core to enhance magnetic flux transmission, along with insulators and PCB housings to secure the sensors effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the overhang part of the rotor is increased to improve magnetic flux transmission to the hall sensor, then the sensing accuracy is improved, but the motor height increases
Solution Approach 1:
The hall sensor is positioned not only radially opposite the rotor but also vertically within the height range of the rotor's overhang portion. This three-dimensional positioning approach allows the sensor to detect magnetic flux more effectively without requiring an increased overall motor height, as the sensor utilizes the vertical space already present in the rotor structure.
Solution Approach 2:
The rotor core's overhang portion acts as an intermediary magnetic flux conduit between the permanent magnet and the hall sensor. By extending the magnetic path through the overhang structure, the patent improves flux transmission to the sensor without needing to increase the distance between the magnet and sensor, thus avoiding height increase.
2Measurement precision
If the hall sensor is positioned closer to the rotor to improve magnetic field detection, then the sensing accuracy is improved, but the motor control reliability deteriorates due to insufficient magnetic flux transmission
Solution Approach 1:
The rotor core's overhang portion serves as a magnetic flux intermediary that channels and concentrates magnetic flux toward the hall sensor. This ensures sufficient magnetic flux transmission even when the sensor is positioned at an optimal detection distance, thereby maintaining both sensing accuracy and motor control reliability simultaneously.
Solution Approach 2:
The overhang portion of the rotor core is specifically designed with enhanced magnetic properties in the local region where it interfaces with the hall sensor. This localized optimization of magnetic flux distribution ensures that the sensor receives adequate flux for accurate detection without compromising overall system reliability.
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 configuration ensures accurate detection of the magnetic field by the hall sensors, enabling precise control of the rotor's rotation without increasing the motor's height or weight, while reducing leakage magnetic flux and improving sensing accuracy.
Implementation Method 1
the hall sensor 50 is disposed to detect a change in the magnetic field in response to the rotation of the rotor 200
Implementation Method 2
the magnetic flux generated from the permanent magnet of the rotor
Data Source
AI summary
BLDC motor including a stator with teeth which extend toward an inner side of a core and have a coil wound therearound; rotors disposed at an inner side of the stator and spaced apart from each other having a plurality of permanent magnets coupled to a core thereof; and hall sensors disposed and spaced apart to be opposite to an outer circumferential surface of the core of the rotor and disposed within a height range between both surfaces in a height direction of the core of the rotor to detect a change in a magnetic field in response to a rotation of the rotor, thereby accurately grasping positional information of a rotor and accurately controlling a rotation of the rotor by transmitting a magnetic flux generated from a permanent magnet of the rotor to a hall sensor enabling the hall sensor to detect a change in a magnetic field.