Automotive Electric Fluidic Pump Rotor Position Detection
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Solution Overview
Problem
Existing automotive electric fluidic pumps with brushless and electronically commutated electric drive motors face challenges in accurately detecting the rotational rotor position, leading to potential start-up problems and increased energy consumption due to inefficiencies in magnetic field detection.
Innovation Solution
The implementation of a ferromagnetic back iron member with axial protrusions that directly magnetically couple Hall sensors, reducing magnetic resistance and improving signal quality for precise rotor position detection, while allowing for economic manufacturing by simplifying the magnetic circuit and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall sensors are arranged on a printed circuit board to detect rotor position, then rotor position detection is enabled, but magnetic resistance increases and signal quality deteriorates
Solution Approach 1:
A ferromagnetic back iron member is introduced as an intermediary component between the Hall sensors and the rotor poles. This back iron member provides a dedicated magnetic conduction path that mediates the magnetic field transmission, reducing magnetic resistance and improving signal quality while enabling accurate rotor position detection through the printed circuit board mounting structure.
2Measurement precision
If Hall sensors are positioned closer to the rotor to improve detection accuracy, then measurement precision improves, but magnetic interference from other components increases
Solution Approach 1:
The ferromagnetic back iron member acts as a magnetic shield and intermediary, positioned between the Hall sensors and surrounding components. It directs magnetic field lines through controlled paths, reducing interference from adjacent magnetic components while maintaining strong coupling with the rotor poles for accurate detection.
Solution Approach 2:
The back iron member features localized protrusions that extend into specific openings in the printed circuit board, creating optimized magnetic conduction paths directly to each Hall sensor. This local quality enhancement ensures strong magnetic coupling at critical detection points while isolating sensors from general magnetic interference in the assembly.
3Measurement precision
If a complex magnetic circuit structure is used to improve signal quality, then measurement precision improves, but manufacturing complexity increases
Solution Approach 1:
The back iron member is integrated with the printed circuit board assembly, combining the magnetic circuit function with the existing sensor mounting structure. The protrusions of the back iron member align with openings in the PCB, creating a unified structure that provides both mechanical support and optimized magnetic conduction without requiring separate complex magnetic circuit components.
Solution Approach 2:
The design optimizes magnetic circuit parameters by controlling the geometry of the back iron member protrusions and their alignment with PCB openings. By adjusting parameters such as protrusion height, diameter, and positioning, the magnetic resistance and signal quality are optimized while maintaining a relatively simple manufacturing structure.
4Measurement precision
If multiple Hall sensors are arranged on the same side of the printed circuit board, then rotor position detection is enabled, but magnetic coupling between sensors is insufficient
Solution Approach 1:
The ferromagnetic back iron member serves as a common magnetic intermediary for multiple Hall sensors arranged on the same side of the PCB. It provides a shared magnetic conduction path that couples all sensors to the rotor poles, ensuring consistent and strong magnetic coupling across all sensor positions without requiring sensors on opposite sides of the board.
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 solution enhances the accuracy of rotor position detection, reduces undesired operational states, and minimizes energy consumption by improving the signal/noise ratio and magnetic coupling, enabling more efficient and cost-effective motor control.
Implementation Method 1
a ferromagnetic back iron member arranged at a distal side of the printed circuit board to provide a direct magnetic coupling of the at least two stator-sided Hall sensors with each other
Implementation Method 2
The ferromagnetic back iron member comprises axial protrusions. A respective one of the axial protrusions is arranged to extend into a respective one of the openings of the printed circuit board
Implementation Method 3
at least two stator-sided Hall sensors arranged on a proximal side of the printed circuit board to face the permanent-magnetic motor rotor. The at least two stator-sided Hall sensors are arranged eccentrically to detect axial magnetic fields of the plurality of rotor poles
Implementation Method 4
The Hall sensors thereby detect the passing rotating magnetic fields generated by the rotor poles
Data Source
AI summary
An automotive electric fluidic pump includes a brushless and electronically commutated electric drive motor. The electric drive motor includes a permanent-magnetic motor rotor which rotates around a rotation axis and includes rotor poles, stator-sided electro-magnetic coils, a printed circuit board with openings, at least two stator-sided Hall sensors arranged on a proximal side of the printed circuit board to face the permanent-magnetic motor rotor, and a ferromagnetic back iron member arranged at a distal side of the printed circuit board to provide a direct magnetic coupling of the Hall sensors with each other. The Hall sensors are arranged eccentrically to detect axial magnetic fields of the rotor poles. The ferromagnetic back iron member comprises axial protrusions. An axial protrusion extends into an opening of the printed circuit board. Each axial protrusion faces a Hall sensor.