Inductive Rotor Angle Sensor Layout for Compact High-Accuracy Motors
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Solution Overview
Problem
Existing sensor arrangements for determining the angular position of rotatable components in electric drives are not compact enough and do not provide sufficient signal quality and accuracy.
Innovation Solution
A sensor arrangement featuring a first annular sensor target with teeth and grooves distributed equidistantly over the circumference, combined with a first inductive sensor having two coils that follow sinusoidal and cosinusoidal paths, and an energizable third coil, allowing for compact design and accurate angular position determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sensor arrangements are used for determining angular position, then the sensor can provide position information, but the axial space requirement is large and signal quality is insufficient
Solution Approach 1:
The sensor target is integrated directly into the rotor structure, with the target disc formed as part of the rotor assembly. The inductive sensor is positioned in the air gap between stator and rotor, nesting the sensing function within the existing motor structure rather than adding separate external sensor housings, thereby reducing axial space while maintaining measurement capability
Solution Approach 2:
The patent transitions from conventional magnetic field sensing to inductive sensing using coils arranged in specific spatial patterns (sinusoidal and cosinusoidal paths). This dimensional reconfiguration of the sensing approach in the air gap allows for more compact axial packaging while improving signal quality through optimized coil geometry and positioning
2Length of stationary object
If the sensor target is integrated into the rotor, then axial space is reduced, but the manufacturing complexity increases
Solution Approach 1:
The sensor target disc is merged with the rotor structure, forming an integrated assembly where the target features are directly formed on or as part of the rotor. This combining of functions reduces the number of separate components and assembly steps, offsetting the increased manufacturing precision requirements through structural integration
Solution Approach 2:
The rotor structure serves multiple functions: it provides mechanical rotation support, houses the sensor target features, and maintains the air gap geometry for inductive sensing. This multi-functionality reduces the need for separate dedicated sensor target components, simplifying the overall manufacturing process despite the integrated design
3Measurement precision
If inductive sensors with sinusoidal and cosinusoidal coil paths are used, then angular position accuracy is improved, but the device complexity increases
Solution Approach 1:
The coils are arranged with specific local geometric properties (sinusoidal and cosinusoidal paths) at specific locations in the air gap. This localized optimization of coil geometry provides the mathematical basis for accurate angular position determination through signal processing, while the rest of the motor structure remains conventional, balancing accuracy with overall system simplicity
Solution Approach 2:
The patent replaces complex mechanical position encoding mechanisms with an inductive sensing system using electromagnetic fields. The sinusoidal and cosinusoidal coil arrangements generate electromagnetic signals that directly encode angular position information, eliminating the need for mechanical encoders or complex target geometries while achieving high measurement precision
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 enables a compact and accurate determination of angular position, suitable for both relative and absolute positioning, with the sensor target being easily integrated into the rotatable component without affecting measuring accuracy, and a control unit for self-contained module design.
Implementation Method 1
the first inductive sensor comprises an energizable third coil
Implementation Method 2
the first inductive sensor has a first coil and a second coil, which respectively extend in a radial plane in relation to the axis of rotation
Data Source
AI summary
The invention relates to a sensor arrangement (1) for determining an angular position of a rotatable component, such as in particular a shaft (2), comprising a first annular sensor target (3) with a plurality of teeth (4) and grooves (5) distributed over the circumference and arranged alternately over the circumference, and also comprising a first inductive sensor (6), which is arranged at a distance axially from the first sensor target (3), and the sensor target (3) and the first inductive sensor (6) are rotatable in relation to one another about a common axis of rotation (7), wherein the first inductive sensor (6) has a first coil (8) and a second coil (9), which respectively extend in a radial plane (10) in relation to the axis of rotation (7), wherein the first coil (8) follows a sinusoidal path along a circular circumference (11) and the second coil (9) follows a path that is phase-offset thereto, in particular a cosinusoidal path, along the circular circumference (11), wherein the first inductive sensor (6) comprises an energizable third coil (12), wherein the energizable third coil (12) is arranged radially offset inside the first coil (8) and the second coil (9), and the grooves (5) are open radially inwards.