Electric Machine Hall Sensor Layout for Precise Rotor Position Detection
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Solution Overview
Problem
Synchronous motors with Hall-effect sensors face measurement uncertainty and adjustment errors, leading to motor torque oscillations due to imprecise detection of the rotor's angular position, especially at high speeds and in large machines.
Innovation Solution
A magnetic field amplifying part is integrated with the stator to enhance the normal component of the magnetic field near the sensors, reducing measurement uncertainty and allowing for precise detection of the rotor's position without altering the existing sensor architecture, and enabling easier adjustment by ensuring congruent angular separation between sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If Hall-effect sensors are used to detect rotor position, then the system structure remains simple, but measurement precision deteriorates due to uncertainty and adjustment errors
Solution Approach 1:
A magnetic field amplifying part is introduced as an intermediary element between the rotor magnets and the Hall-effect sensors. This part concentrates and amplifies the magnetic field lines in the region where the sensors are located, thereby enhancing the magnetic field intensity without modifying the sensors themselves or the rotor structure. The amplifying part acts as a mediator that transforms the weak magnetic field into a stronger one, improving measurement precision while keeping the overall system structure relatively simple.
Solution Approach 2:
The invention changes the magnetic field parameter (intensity) in the sensor region by introducing the amplifying part. By modifying the magnetic field distribution and concentration in the air gap, the system achieves better sensor performance. The amplifying part alters the magnetic field parameters locally without changing the global system configuration, thereby improving measurement precision while maintaining structural simplicity.
2Power
If the size of the electrical machine is increased, then power output is improved, but measurement precision deteriorates due to increased measurement uncertainty
Solution Approach 1:
The magnetic field amplifying part is designed to provide localized magnetic field enhancement only in the specific region where the Hall-effect sensors are positioned. This local quality improvement allows the system to maintain high measurement precision in the sensor region while the overall machine size can be increased for higher power output. The amplifying part creates a localized zone of enhanced magnetic field intensity without affecting the global machine dimensions.
3Ease of manufacture
If sensor adjustment tolerance is relaxed, then ease of assembly is improved, but measurement precision deteriorates due to polarity detection errors
Solution Approach 1:
The magnetic field amplifying part serves as a mediator that compensates for sensor misalignment and adjustment errors. By concentrating and amplifying the magnetic field lines, it creates a more robust magnetic field signature that is less sensitive to small variations in sensor position and orientation. This allows for relaxed assembly tolerances while maintaining accurate polarity inversion detection, as the amplified field provides clearer signal transitions even when sensors are not perfectly positioned.
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 solution improves the precision of rotor position detection, reduces torque oscillations, and maintains the system's lightweight and minimal bulk, making it suitable for applications like aeronautics by amplifying the magnetic field gradient, thus minimizing the impact of sensor uncertainty and adjustment errors.
Implementation Method 1
The part (7) comprises a zone (7b) configured to amplify the normal component of the magnetic field at the magnetic sensor (6b), in particular the gradient of the normal component of the magnetic field
Implementation Method 2
magnetic sensors such as Hall-effect sensors. These sensors can measure the orientation of a normal component of the magnetic field
Data Source
AI summary
The invention relates to an electric machine comprising a rotor and a stator. The rotor (40, 4) comprises a plurality of permanent magnets (4), the stator comprises a plurality of coils suitable for being powered by an electric current and two Hall effect sensors (6) on supports (60). The sensors are configured to detect a change in gradient of the normal component of a magnetic field generated by the permanent magnets (4). The stator comprises a part (7) comprising —a first zone (7a), —a second zone (7b), and a third zone (7c) extending from the first zone (7a) up to the second zone (7b). The maximum radial thickness of the third zone (7c) is less than the minimum radial thickness of the first zone and the second zone.