Brushless DC Motor Actuator Remote Commutation Sensing
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Solution Overview
Problem
Existing brushless DC motor commutation sensing technologies rely on discrete Hall Effect sensors, which are costly and require complex interconnections, necessitating a more reliable and cost-effective sensing method.
Innovation Solution
The use of ferromagnetic elements embedded in the stator to magnetically couple with surface-mount Hall Effect sensors on a circuit board, allowing for reliable sensing of the rotor magnet's magnetic fields without the need for leaded sensors, with embodiments featuring ferromagnetic elements at the radial and axial peripheries of the rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discrete Hall Effect sensors are used for commutation sensing, then reliable magnetic field sensing is achieved, but manufacturing costs increase and device complexity increases due to interconnections
Solution Approach 1:
The patent merges the Hall Effect sensors with the stator structure by embedding them directly into the stator body, eliminating the need for separate sensor housings and complex interconnection circuits. This integration maintains sensing reliability while reducing device complexity and manufacturing costs.
Solution Approach 2:
The patent introduces ferromagnetic elements as intermediaries between the rotor magnet and the Hall Effect sensors. These elements concentrate and guide the magnetic field lines, enabling reliable sensing at greater distances from the rotor, thereby simplifying the overall sensor arrangement and reducing interconnection complexity.
2Reliability
If Hall Effect sensors are positioned close to the rotor magnet, then sensing reliability improves, but manufacturing complexity increases due to precise positioning requirements
Solution Approach 1:
Ferromagnetic elements are introduced as intermediaries between the rotor magnet and the Hall Effect sensors. These elements concentrate and guide magnetic field lines, allowing the sensors to be positioned at greater distances from the rotor while maintaining sensing reliability, thereby reducing manufacturing precision requirements.
Solution Approach 2:
The patent extracts the magnetic field concentration function from the sensor positioning requirement and assigns it to separate ferromagnetic elements. This allows the sensors to be positioned more freely without compromising sensing reliability, reducing the need for precise positioning during manufacturing.
3Reliability
If embedded Hall Effect sensors are used in the stator, then sensing reliability improves, but manufacturing costs increase due to embedding process complexity
Solution Approach 1:
Ferromagnetic elements serve as intermediaries that amplify and guide the magnetic field, allowing the use of simpler, less expensive sensor embedding techniques while maintaining high sensing reliability. The ferromagnetic elements compensate for the reduced proximity between sensors and rotor.
Solution Approach 2:
The patent uses ferromagnetic elements to create a replicated or amplified version of the rotor's magnetic field pattern at the sensor location. This allows standard Hall Effect sensors to detect the magnetic field accurately without requiring complex embedding procedures or ultra-precise positioning.
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 reduces manufacturing costs while maintaining reliability by eliminating the need for discrete Hall Effect sensors and their interconnections, enabling efficient commutation sensing in brushless DC motors.
Implementation Method 1
ferromagnetic elements partially embedded in the stator in proximity to the periphery of the rotor magnetically couple the rotor magnet to the circuit board mounted Hall Effect sensors
Implementation Method 2
ferromagnetic elements partially embedded in the stator
Implementation Method 3
commutation sensing is achieved with an array of Hall Effect sensors responsive to magnetic field domains produced by the rotor magnet
Data Source
AI summary
A brushless DC motor and Hall Effect commutation sensors are mounted on a common circuit board, and ferromagnetic elements partially embedded in the motor stator in proximity to the periphery of the rotor magnetically couple the rotor magnet to the Hall Effect sensors. Preferably, the ferromagnetic elements are embedded in the stator adjacent the radial periphery of the rotor magnet. Alternately, the ferromagnetic elements can be embedded in the stator adjacent the axial periphery of the rotor magnet.