Hall Sensor Thermo-EMF Compensation via Differential Temperature Sensing
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Solution Overview
Problem
Conventional sensor systems face challenges in accurately compensating for thermal electromotive force (EMF) effects, which lead to residual offset errors in magnetic field sensing, particularly in Hall effect devices, due to temperature-related charge movements and gradients, making it difficult to maintain signal accuracy over the device's operational lifetime.
Innovation Solution
A sensor system is designed with temperature or temperature gradient sensors arranged proximate to the Hall plate, which senses temperature changes in each operating phase and combines these signals to provide a compensation signal, effectively reducing thermal EMF-related errors by quantifying the Seebeck coefficient of materials used and using differential temperature measurements across contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional temperature compensation methods are used with spinning Hall schemes, then some offset correction is achieved, but residual offset errors remain due to stochastic nature and temperature changes over device lifetime
Solution Approach 1:
The patent changes the parameter being measured from simple temperature to temperature difference (ΔT) between two specific points. By measuring the temperature gradient rather than absolute temperature, the system adapts to temperature changes over time and maintains compensation accuracy throughout the device lifetime, resolving the reliability issue while maintaining measurement precision.
Solution Approach 2:
The patent introduces a second temperature sensor as an intermediary element to measure the temperature at a reference point. This intermediary sensor enables differential measurement that cancels out common-mode temperature variations, providing stable long-term compensation without requiring absolute temperature accuracy.
2Object-generated harmful factors
If polarity inversion is used in sequential operating phases, then thermal EMF effects are presumed to be canceled, but temperature distribution changes when polarity is inverted, preventing complete cancellation
Solution Approach 1:
The patent implements feedback by measuring the actual temperature difference between contacts and using this measurement to calculate and apply a compensation signal. This closed-loop approach accounts for the actual temperature distribution regardless of polarity inversion effects, completely canceling thermal EMF-induced offset errors rather than merely presuming cancellation.
3Measurement precision
If residual offset compensation is added to spinning Hall schemes, then device complexity increases, but this enables correction of stochastic offset errors
Solution Approach 1:
The patent makes the temperature sensors serve multiple functions: they simultaneously provide temperature information for compensation calculations and enable detection of temperature gradients. This multi-functionality reduces the need for separate specialized components, achieving accurate offset compensation without proportionally increasing device complexity.
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 approach significantly reduces residual offset errors by accurately accounting for thermal EMF effects, enhancing the accuracy and reliability of sensor output signals over the device's operational lifetime, even as temperature conditions change.
Implementation Method 1
a temperature sensor arranged proximate a Hall plate configured to sense a temperature change in each operating phase
Implementation Method 2
Hall plates which are operated in sequential operating phases
Implementation Method 3
thermal electromotive force (thermo-EMF), which relates to the effects temperature can have on the movement of electric charge in a material
Data Source
AI summary
A method for correcting the output of a Hall effect device for thermal electromotive force (thermo-EMF) utilizing the steps of: (1) supplying energy to the Hall effect device, (2) measuring a first output of the Hall effect device as a result of the supplying energy, (3) stopping the supply of energy to the Hall effect device, (4) waiting a period of time, (5) measuring a second output of the Hall device in response to a temperature difference between the output measurement location and a reference point, and (6) combining the first and second outputs to determine an output corrected for thermo-EMF.