Inductive Position Sensor Sinusoidal Windings Harmonic Signal Strength
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Solution Overview
Problem
Inductive position sensors with square waveform windings face challenges in measuring smooth sinusoidal signals, especially when the coupling element is short or the airgap is small, leading to impractical increases in winding size and reduced linearity due to harmonic interactions.
Innovation Solution
Incorporating one or more scaled harmonics into sinusoidally shaped windings, allowing for improved signal strength and transfer function without increasing the winding width, by adding harmonics such as the third harmonic scaled to ⅙th of the sinusoidal waveform amplitude, which are naturally eliminated in differential measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If square waveform windings are used to enhance signal strength, then the measurement capability improves, but the linearity deteriorates due to harmonic interactions
Solution Approach 1:
The patent transforms the winding waveform from a square wave to a sinusoidal waveform, fundamentally changing the parameter of wave shape. This eliminates harmonic interactions while maintaining measurement capability through the sinusoidal signal's smooth characteristics, thereby resolving the contradiction between measurement precision and linearity.
2Reliability
If winding size is increased to improve signal strength for short coupling elements or small airgaps, then the transfer function improves, but the device complexity and size increase
Solution Approach 1:
The patent changes the waveform parameter from square to sinusoidal, which fundamentally alters the signal characteristics. This enables achieving the required transfer function with appropriately sized sinusoidal windings, avoiding the need to excessively increase winding size while maintaining reliability for short coupling elements or small airgaps.
3Measurement precision
If sinusoidal windings are used to maintain linearity, then the measurement accuracy improves, but the signal strength decreases for short coupling elements or small airgaps
Solution Approach 1:
The patent optimizes the sinusoidal winding parameters including amplitude, frequency, and spatial distribution to achieve the right balance. By carefully tuning these parameters, the sinusoidal windings generate sufficient signal strength for short coupling elements or small airgaps while preserving the linearity and measurement accuracy inherent in sinusoidal waveforms.
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 configuration enhances signal strength and transfer function while maintaining linearity, enabling more reliable detection of relative positions with reduced power consumption and smaller sensor size, allowing for longer measurement paths and easier integration into existing systems.
Implementation Method 1
the field generated by alternating current flowing through the transmit aerial induces an electromotive force in the receive aerial that generates a current that is dependent on the position of the coupling element relative to the transmit and receive aerials
Data Source
AI summary
An inductive position sensor may be configured to detect relative position between a first member and a second member. The inductive position sensor may include a transmit aerial configured to be disposed on the first member. The inductive position sensor may include a receive aerial configured to be disposed on the first member. The inductive position sensor may include processing circuitry configured to provide one or more signals indicative of the relative position between the first member and the second member based on a receive signal induced in the receive aerial resulting from a signal provided to the transmit aerial. One or more of the transmit aerial and the receive aerial may include one or more windings. A shape of the one or more windings can be a combination of a sinusoidal waveform and one or more scaled harmonics of the sinusoidal waveform.