Orthogonal Hall Sensor Differential Interference Rejection
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Solution Overview
Problem
Hall sensors used for current sensing in motor drives are susceptible to magnetic field interference, which existing differential configurations fail to fully attenuate, leading to increased circuit complexity, cost, and power consumption due to the need for additional circuitry.
Innovation Solution
A system comprising two Hall-effect sensors with orthogonal bias current directions and out-of-phase sense output terminals, coupled to a shared amplifier, which effectively subtracts interference signals without requiring separate amplifiers or additional signal processing circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple Hall elements are used in differential sensing configurations, then first order magnetic field interference is attenuated and offset cancellation is improved, but gradient interference is not attenuated and circuit complexity increases
Solution Approach 1:
The patent divides the sensing function into two separate Hall effect sensors positioned at different locations, with each sensor handling a portion of the differential measurement. This segmentation allows the system to process interference rejection at the sensor level rather than requiring complex post-processing circuitry for multiple elements.
Solution Approach 2:
The patent introduces spatial positioning as a new dimension for interference rejection. By placing Hall effect sensors at different physical locations and using out-of-phase connections, the system creates a spatial differential that naturally rejects gradient interference, moving beyond traditional electrical differential approaches.
2Measurement precision
If multiple Hall sensors are used with duplicated switching networks and preamplifiers, then sensing accuracy is improved, but cost and power consumption increase
Solution Approach 1:
The patent merges the signal processing resources by using a single shared amplifier and switching network to serve both Hall effect sensors. This consolidation maintains the differential sensing accuracy while eliminating the need for duplicated preamplifiers and signal chain components, directly reducing power consumption and cost.
Solution Approach 2:
The shared amplifier and switching network perform multiple functions: they process signals from both Hall sensors, implement the out-of-phase differential measurement, and provide interference rejection. This multi-functionality eliminates redundant components and reduces overall system power consumption while maintaining measurement precision.
3Object-affected harmful factors
If multiple Hall sensors are used with duplicated circuitry, then interference rejection is improved, but circuit area increases
Solution Approach 1:
The patent combines the signal processing circuitry into a shared amplifier and switching network that serves both Hall effect sensors. This merging approach maintains effective interference rejection through the out-of-phase differential configuration while minimizing the total circuit area by eliminating redundant components.
Solution Approach 2:
Instead of duplicating circuitry for each sensor, the patent inverts the approach by having multiple sensors share a single processing chain. The interference rejection is achieved not through redundant amplifiers but through the spatial and phase differential created by the sensor configuration and out-of-phase connections to the shared amplifier.
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 reduces interference effects while maintaining differential sensing capabilities with minimal increase in circuit complexity or power consumption, compatible with high-bandwidth architectures and scalable to systems using multiple Hall-effect sensors.
Implementation Method 1
Hall sensors are used for current sensing in a variety of applications, such as providing current feedback signals in motor drives
Data Source
AI summary
A system comprises first and second Hall-effect sensors and an amplifier. The first Hall-effect sensor has a first bias current direction parallel to a first direction, a pair of first bias input terminals spaced along the first direction, and a pair of first sense output terminals spaced along an orthogonal second direction. The second Hall-effect sensor has a second bias current direction parallel to the second direction, a pair of second bias input terminals spaced along the second direction, and a pair of second sense output terminals connected out of phase with the first sense terminals. The amplifier has a pair of amplifier input terminals coupled to the first and second sense terminals.