Vertical Hall Sensor Offset Reduction via Insulated Electrodes
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Solution Overview
Problem
Vertical Hall Effect sensors face challenges in reducing offset errors due to asymmetries and self-generated parasitic magnetic fields, which are not effectively addressed by existing methods like sensor combination and spinning current techniques, especially when there are gradients or disturbances in current flow direction.
Innovation Solution
The introduction of electrodes insulated from the active region between contacts creates a counter gradient by controlling current flow, using a processor to apply voltages and manage the spinning current, thereby reducing offset errors and achieving balanced input resistance across phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If vertical hall effect sensors are used to detect rotor position in electric power steering systems, then the sensor structure can be compact and suitable for limited space, but offset errors occur due to misalignment between the sensor and magnet assembly
Solution Approach 1:
The system continuously monitors the detected rotor position and compares it with expected position values. When an offset error is detected, the system automatically compensates by adjusting the position readings in real-time, ensuring accurate control signals are sent to the motor despite physical misalignment between sensor and magnet assemblies
Solution Approach 2:
The patent changes the operational parameters of the hall effect sensor by applying different magnetic field strengths and analyzing the nonlinear relationship between sensor output and rotor position. By characterizing the sensor response across multiple operating points and using curve fitting algorithms, the system compensates for offset errors without requiring perfect physical alignment
2Productivity
If automated assembly processes are used to reduce manufacturing costs and improve consistency, then production efficiency increases, but precise alignment between sensor and magnet assemblies becomes more difficult to achieve
Solution Approach 1:
The system performs preliminary characterization of each sensor-magnet assembly during or immediately after assembly. By pre-measuring the offset error for each individual assembly and storing compensation values in memory, the system prepares correction data before actual operation begins, eliminating the need for high-precision alignment during automated assembly
Solution Approach 2:
The sensor system performs self-diagnosis and self-correction by automatically detecting its own offset errors and compensating for them through software algorithms. This self-service capability eliminates the need for external calibration equipment or manual adjustment procedures, making the system ideal for high-volume automated manufacturing
3Device complexity
If conventional hall effect sensors are used without offset compensation, then the device complexity remains low, but measurement accuracy deteriorates due to alignment errors
Solution Approach 1:
The control unit performs multiple functions: it processes the raw sensor signals, compensates for offset errors, determines rotor position, and generates motor control signals. By integrating the compensation algorithm into the existing control unit rather than adding separate hardware components, the system achieves high measurement precision without significantly increasing overall device complexity
Solution Approach 2:
The patent introduces a software-based intermediary layer between the physical sensor and the control system. This software layer processes the raw sensor data, applies offset compensation algorithms, and outputs corrected position information. This intermediary approach maintains simplicity in hardware while achieving high measurement accuracy through intelligent signal processing
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 effectively cancels offset errors and self-generated parasitic magnetic fields, ensuring accurate magnetic field measurements by creating a depletion region and applying symmetric voltages to maintain balanced input resistance, enhancing the reliability of vertical Hall Effect sensors.
Implementation Method 1
Vertical hall effect sensors have been used to detect the position of a rotor in an electric motor
Data Source
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AI summary
A vertical Hall Effect sensor assembly in one embodiment includes a first sensor with a first doped substrate, a first doped well, the first doped well having a doping opposite to the first doped substrate, a first endmost inner contact accessible at a first surface of the first sensor and located at a first end portion of the first doped well, a first intermediate inner contact accessible at the first surface and located between the first endmost inner contact and a second end portion of the first doped well, and a first electrode positioned on the first surface immediately adjacent to the first endmost inner contact and the first intermediate inner contact, the first electrode electrically isolated from the first doped well, and a first voltage source operably connected to the first electrode.