Variable Inductance Position Sensor Current Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing radial shaft position sensors face challenges with noise, coupling, and linearity issues, particularly requiring high excitation voltage and power consumption, and are prone to noise due to high impedance sensing wires, which increases cost and complexity.
Innovation Solution
A variable inductance type position sensor system that uses current sensing instead of voltage sensing, with induction coils connected to AC voltage sources and a detector device to measure current changes, allowing for simplified electronic circuitry and reduced power consumption, and incorporates capacitors to improve linearity and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage sensing is used in radial shaft position sensors, then measurement capability is provided, but noise and coupling issues occur due to high impedance sensing wires
Solution Approach 1:
The patent replaces voltage sensing with current sensing in the radial shaft position sensor system. By measuring current through the sensing wires instead of voltage, the system avoids the high impedance problems that cause noise and coupling issues. The current sensing approach uses low impedance connections that are inherently more immune to electrical noise and interference.
2Measurement precision
If high excitation voltage is used to achieve good signal to noise ratio, then measurement quality improves, but power consumption increases
Solution Approach 1:
The patent substitutes voltage sensing with current sensing, which fundamentally changes the electrical characteristics of the measurement system. Current sensing allows for lower excitation voltages because the measurement is based on current magnitude rather than voltage magnitude, directly reducing power consumption while maintaining or improving signal quality.
3Object-affected harmful factors
If shielded cables are used to reduce noise, then immunity to electrical noise improves, but cost and complexity increase
Solution Approach 1:
The patent replaces voltage sensing with current sensing, which changes the electrical impedance characteristics of the sensing circuit. Current sensing uses low impedance connections that are naturally immune to electrical noise and interference, eliminating the need for expensive and complex shielded cables. The low impedance current measurement paths inherently reject noise without requiring additional shielding components.
4Measurement precision
If conventional voltage sensing circuitry is used, then position detection is achieved, but linearity and sensitivity are limited
Solution Approach 1:
The patent substitutes voltage sensing with current sensing, which provides different electrical characteristics for position measurement. Current sensing through the sensing wires allows for improved linearity because the current magnitude directly reflects the position-dependent impedance changes without the high impedance effects that cause non-linearity in voltage sensing systems.
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 enhances linearity and signal/noise ratio, reduces power consumption and costs, and eliminates the need for shielded cables, providing improved performance and immunity to electrical noise.
Implementation Method 1
Each sensing element 31 to 34 includes two pole pieces and should include at least one coil 5
Implementation Method 2
a detector device being interposed between said first connection point and said second end of said first AC voltage source in order to deliver information about the magnitude of the current flowing between said first connection point and said second end of said first AC voltage source
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
The variable inductance type position sensor system comprises a rotor target (104) of ferromagnetic material fixed on a rotary shaft (110) and a stationary magnetic circuit (103) which is placed around the rotor target (104). The stationary magnetic circuit (103) comprises a sensing element (131) located along an axis X-X' in front of the rotor target (104) while leaving an air gap. The sensing element (131) receives an induction coil (105). A first end of the induction coil (105) of the sensing element (131) is connected to a first end (198) of an AC voltage source (101), and a second end of the induction coil (105) of the sensing element (131) is connected to a connection point (199), which is connected to a second end (181) of the AC voltage source (101), the second end (181) of the AC voltage source (101) being connected to a reference voltage. A detector device (162) is interposed between the connection point (199) and the second end (181) of the AC voltage source (101) in order to deliver information about the magnitude of the current flowing between the connection point (199) and the second end (181) of the first AC voltage source (101), this information representing the value of a modification x to the width of the air gap that presents a predetermined nominal value go along said first axis X-X'.