Inductive Position Sensor Assembly for Electric Machine Rotor Alignment
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Solution Overview
Problem
Existing rotary electric machines face complexity in calibration and real-time control due to the need for modulated sine/cosine signals from resolvers, which increases structural and control complexity.
Innovation Solution
A position sensor assembly that generates unmodulated sine/cosine signals using an inductive-based sensor with a sensor rotor and stator, aligned with the machine rotor and stator, simplifying calibration and reducing complexity by providing a calibrated reference angle for the controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resolver is used to provide sine/cosine signals, then rotor position and speed can be determined, but structural complexity and control complexity increase due to modulation requirements
Solution Approach 1:
The patent extracts and eliminates the modulation function from the sensor system. Instead of using a resolver that outputs modulated signals requiring demodulation, the invention uses an inductive sensor that directly outputs unmodulated sine and cosine signals, removing the complexity of modulation/demodulation circuits and control logic while maintaining accurate rotor position and speed measurement
Solution Approach 2:
The patent replaces the traditional resolver mechanism (which relies on mechanical rotation and magnetic coupling producing modulated signals) with an inductive sensor system that uses electromagnetic induction to directly generate unmodulated position signals. This substitution eliminates the need for complex signal processing while achieving the same measurement function
2Measurement precision
If a resolver with control logic is used, then accurate position sensing is achieved, but calibration complexity increases
Solution Approach 1:
The inductive sensor assembly is designed to self-calibrate by utilizing the existing magnetic field geometry of the motor. The sensor automatically establishes its reference frame based on the stator magnet positions during normal operation, eliminating the need for separate calibration procedures or complex calibration logic while maintaining accurate position sensing
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 simplifies sensor calibration efforts and reduces overall structural and control complexity, enabling accurate rotor position and speed control in electric machines, enhancing operational efficiency.
Implementation Method 1
an inductive-based sensor configured to output such unmodulated sine/cosine signals
Implementation Method 2
A resolver operating in accordance with the principle of reluctance and excitation in the 4-10 kHz range
Data Source
AI summary
An electric machine includes a machine rotor circumscribed by a machine stator, and having a rotor shaft, rotor stack, and end cap which rotate about an axis. The end cap includes lobes equal in number to a number of pole pairs of the machine rotor. A position sensor assembly has a predetermined alignment with the machine rotor and stator. The sensor assembly includes a sensor rotor formed by the lobes and a sensor stator having a printed circuit board with conductive sine and cosine traces. Machine rotor rotation causes the sensor assembly to output an unmodulated sine and cosine signals to a controller, which then calculates a calibrated reference angle. A magnetic axis of an electrical phase of the machine is aligned with and bisects a peak of the sine trace. A direct axis of the machine rotor aligns with an edge of a lobe.