Polyphase Motor Rotor Position Sensor Using Radial Field Detection
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Solution Overview
Problem
Existing methods for determining the angular position and speed of rotation of a rotor in motor vehicle polyphase electric motors face challenges in precision and parasitic influence elimination, particularly with high-cost equipment and complex alignment procedures.
Innovation Solution
A device comprising multiple magnetic field sensors fixed to the stator with an L-shaped sensor carrier and tongues for precise detection of the radial component of the magnetic field, integrated with Hall effect sensors and a compact design to simplify signal processing and installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resolver is used to determine angular position and speed, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The invention extracts only the necessary measurement function from a complete resolver system. Instead of using a full resolver with both sine and cosine windings, the patent uses a simplified sensor arrangement that directly measures the magnetic field components, eliminating unnecessary components while maintaining measurement precision.
Solution Approach 2:
The invention creates a simplified copy of the resolver functionality using Hall effect sensors that directly measure magnetic field components. This copy performs the same angular position determination function but with simpler hardware, avoiding the complexity of a complete resolver system.
2Device complexity
If Hall effect sensors are used to determine angular position, then device complexity is reduced, but measurement precision deteriorates due to parasitic influences
Solution Approach 1:
The invention introduces an intermediary processing step that separates the useful magnetic field signals from parasitic influences. By measuring both radial and tangential components and processing these signals together, the system eliminates parasitic effects while maintaining the simplicity of Hall effect sensors.
Solution Approach 2:
The invention changes the measurement parameters by simultaneously measuring both radial and tangential magnetic field components instead of relying on a single component. This parameter change allows the system to eliminate parasitic influences through signal processing while using simple Hall effect sensors.
3Object-affected harmful factors
If sensors are arranged with large housing faces extending in tangential planes, then parasitic influences are eliminated, but manufacturing precision requirements increase
Solution Approach 1:
The invention segments the magnetic field measurement into two independent components: radial and tangential. By using separate sensor arrangements for each component, the system eliminates parasitic influences while using simple alignment references (stator teeth) that are easy to manufacture.
Solution Approach 2:
The invention uses the stator teeth structure itself as the alignment reference for sensor placement. The sensors are positioned relative to the easily manufacturable stator teeth, which automatically provide the correct geometric reference, eliminating the need for complex external alignment procedures.
4Measurement precision
If complex alignment procedures are used to position sensors, then measurement precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The invention uses the stator teeth structure itself as the alignment reference for sensor placement. The sensors are positioned relative to the easily manufacturable stator teeth, which automatically provide the correct geometric reference, eliminating the need for complex external alignment procedures.
Solution Approach 2:
The invention changes the alignment reference from complex external fixtures to the simple stator teeth structure. This parameter change in the reference system makes the alignment procedure simple while maintaining measurement precision through the geometric relationship between sensors and stator teeth.
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 provides precise angular position and speed determination with reduced parasitic influences and cost-effectiveness, ensuring efficient operation of the motor without complex alignment, suitable for high-power hybrid vehicle applications.
Implementation Method 1
a plurality of magnetic field sensors fixed relative to the stator, the sensors being arranged in notches defining successive stator teeth and having large housing faces extending in tangential planes of the stator magnetic mass so that the sensors detect only a radial component of the magnetic field within the stator magnetic mass
Implementation Method 2
Means for processing first signals delivered by Hall effect sensors supply second signals representative of the angular position of the rotor, of the speed of rotation and of other information useful for the operation of the inverter
Data Source
Figure 1
Figure 2~3
Figure 4a
AI summary
The invention relates to a polyphase electric motor (1) of a motor vehicle which includes a rotor (6) and a stator (2, 5, 13) surrounding the rotor and including a plurality of stator windings (5) around stator teeth (4, 19) defined by notches (3) in a stator magnetic mass (2). According to the invention, the motor includes a device for determining an angular position (17) and/or the speed of rotation of the rotor, including a plurality of magnetic field sensors (18) which are stationary relative to the stator. The sensors are arranged in notches (3) and comprise large casing surfaces extending in planes that are tangential to the stator magnetic mass, such that the sensors detect only a radial component of the magnetic field inside the stator magnetic mass.