Dual-Data PWM Encoding for Eddy-Current Sensor Temperature Compensation
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Solution Overview
Problem
Eddy current sensors face challenges in accurately measuring both position and temperature of conductive targets due to temperature-induced changes in impedance, often requiring additional temperature sensors, which increase cost and complexity.
Innovation Solution
Encoding temperature and position data in a single pulse width modulation (PWM) signal using duty cycle, frequency, and logic levels, allowing the eddy current sensor to correct for temperature variations and output combined data to a controller for actuator control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an auxiliary dedicated temperature sensor is used to measure temperature, then temperature measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The eddy current sensor is designed to perform dual functions: measuring both position and temperature. The sensor coil measures impedance changes caused by both target position and temperature variations. By encoding both position duty cycle and temperature frequency information in a single PWM output signal, the system eliminates the need for separate temperature and position sensors, reducing device complexity while maintaining measurement capabilities
Solution Approach 2:
The patent combines temperature measurement and position measurement into a single integrated sensing and output system. The PWM signal merges position data (duty cycle) and temperature data (frequency) into one communication channel, eliminating the need for multiple separate sensors and signal lines, thus reducing overall system complexity
2Measurement precision
If an auxiliary dedicated temperature sensor is used to measure temperature, then temperature measurement accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The eddy current sensor is designed to perform dual functions: measuring both position and temperature. The sensor coil measures impedance changes caused by both target position and temperature variations. By encoding both position duty cycle and temperature frequency information in a single PWM output signal, the system eliminates the need for separate temperature and position sensors, reducing device complexity while maintaining measurement capabilities
Solution Approach 2:
The patent combines temperature measurement and position measurement into a single integrated sensing and output system. The PWM signal merges position data (duty cycle) and temperature data (frequency) into one communication channel, eliminating the need for multiple separate sensors and signal lines, thus reducing overall system complexity
3Reliability
If temperature compensation is implemented using a separate temperature sensor, then temperature compensation accuracy is improved, but the number of components increases
Solution Approach 1:
The eddy current sensor performs self-diagnosis by measuring its own impedance temperature coefficient. The sensor uses its inherent thermal response to temperature changes as a natural reference, eliminating the need for external temperature sensors. The microcontroller calculates the temperature coefficient by comparing impedance changes at different temperatures, enabling the sensor to compensate for its own temperature drift without additional components
Solution Approach 2:
The eddy current sensor is designed to perform dual functions: measuring both position and temperature. The sensor coil measures impedance changes caused by both target position and temperature variations. By encoding both position duty cycle and temperature frequency information in a single PWM output signal, the system eliminates the need for separate temperature and position sensors, reducing device complexity while maintaining measurement capabilities
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
Enables efficient communication of both position and temperature without the need for additional temperature sensors, reducing manufacturing costs and enhancing system performance by integrating temperature compensation within the PWM signal.
Implementation Method 1
The sensor coil may be configured to output a magnetic field extending outward from the eddy current sensor. The electrically conductive target may interact with the magnetic field resulting in an eddy current resulting in a change of impedance at the sensor coil
Implementation Method 2
The electrically conductive target may interact with the magnetic field resulting in an eddy current resulting in a change of impedance at the sensor coil which is proportional to a distance between the electrically conductive target and the sensor coil
Data Source
AI summary
Methods and systems are provided for encoding position and temperature in a pulse width modulation (PWM) signal. The method includes acquiring a PWM signal from an eddy current sensor, and determining the temperature of the eddy current sensor based on a PWM signal feature. The PWM signal feature is a PWM frequency and/or a PWM logic level.