Solenoid Inductance Sensing for Sensorless Position Estimation
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Solution Overview
Problem
Traditional solenoid systems require a separate sensor to determine solenoid position, which is not always necessary or efficient.
Innovation Solution
An inductance module is configured to input an AC excitation signal to the solenoid, compare the current-voltage phase shift between solenoid current and voltage, and output a signal indicative of solenoid inductance, allowing for the determination of solenoid position without an independent position sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate sensor is used to determine solenoid position, then position measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The solenoid coil serves dual purposes: actuating the solenoid and sensing its position through inductance measurement. The same coil that generates the magnetic field for actuation also provides the inductance signal that indicates plunger position, eliminating the need for separate position sensors.
Solution Approach 2:
The solenoid coil is made multi-functional by using it both for actuation and for position sensing. The system measures inductance changes of the coil to determine plunger position, allowing one component to perform multiple functions and reducing overall system complexity.
2Measurement precision
If an AC excitation signal is applied to measure inductance, then position estimation accuracy is improved, but energy consumption increases
Solution Approach 1:
An AC excitation signal is applied periodically to the solenoid coil to measure inductance changes. The periodic excitation allows for accurate inductance measurement while enabling the system to return to its steady state between measurements, balancing accuracy with energy efficiency.
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 method enables accurate solenoid position estimation by correlating solenoid inductance to the phase shift, providing a sensorless solution for determining solenoid position, which is robust against external factors like temperature and resistance changes.
Implementation Method 1
determine and/or compare a current-voltage (CV) phase shift between a solenoid current and solenoid voltage
Implementation Method 2
input an AC excitation signal to the solenoid, determine and/or compare a current-voltage (CV) phase shift between a solenoid current and solenoid voltage, and output an output signal indicative of solenoid inductance
Implementation Method 3
The synchronous demodulator module can be operatively connected to the zero-cross comparator module to receive the clock signal at a quadrature clock thereof to output a quadrature clock signal, to sum the AC component and the quadrature clock signal at a quadrature comparator, and to output a demodulator signal having a modified wave shape with an average amplitude indicative of inductance of the solenoid
Implementation Method 4
the quadrature clock can allow the synchronous demodulator to be sensitive to the imaginary portion of the solenoid voltage which is indicative of the solenoid inductance
Data Source
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AI summary
A system (100) can include an inductance module (101) configured to operatively connect to a solenoid (103). The inductance module can be configured to input an AC excitation signal to the solenoid, determine and/or compare a current-voltage (CV) phase shift between a solenoid current and solenoid voltage, and output an output signal indicative of solenoid inductance based on the CV phase shift.