Magnetic Field Sensor Gain Setting for Electric Motor Positioning
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Solution Overview
Problem
Existing methods for setting gain in magnetic field sensors for electric motor position determination face challenges due to mechanical and dynamic tolerances, requiring two microcontrollers for varying gain, which increases costs and affects functional safety, and struggle to reliably preset gain for different actuator embodiments, leading to potential signal saturation or poor signal-to-noise ratios.
Innovation Solution
A method and apparatus where the evaluation unit on a printed circuit board adjusts the gain of the magnetic field sensor by emitting signals for coarse and fine adjustments, allowing for adaptive correction of static tolerances and dynamic changes in the magnetic field signal, even without a programming voltage, using an analog interface to transmit gain settings via unused connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed gain value is preprogrammed in the evaluation unit, then the device complexity is reduced, but the reliability deteriorates due to inability to correct mechanical and dynamic tolerances
Solution Approach 1:
The patent implements dynamic gain adjustment by introducing a gain adjustment register that can be modified during operation. The evaluation unit can write different gain values to this register based on detected rotor positions and operating conditions, allowing the system to adapt to mechanical tolerances and dynamic changes without adding complex hardware structures.
Solution Approach 2:
The evaluation unit performs self-calibration by detecting rotor positions and automatically adjusting the gain value stored in the gain adjustment register. This self-service mechanism allows the system to compensate for its own mechanical tolerances and maintain reliable operation without external intervention or complex additional components.
2Adaptability or versatility
If two microcontrollers are used to vary gain dynamically, then the adaptability is improved, but the device complexity and cost increase
Solution Approach 1:
The evaluation unit is designed to perform multiple functions: it evaluates rotor position signals, controls commutation of the electric motor, and simultaneously adjusts the gain of the magnetic field sensor. This multi-functionality eliminates the need for a separate microcontroller dedicated solely to gain adjustment, reducing device complexity while maintaining adaptability.
Solution Approach 2:
The patent merges the gain control function with the existing evaluation unit by integrating a gain adjustment register into the same hardware structure. This consolidation combines position evaluation and gain control into a single integrated unit, avoiding the need for two separate microcontrollers and reducing overall system complexity.
3Reliability
If a large slope is used for gain setting, then the reliability is improved for actuators with small air gaps, but the measurement precision deteriorates due to sensor saturation
Solution Approach 1:
The patent implements dynamic gain adjustment that adapts to the specific actuator configuration. By detecting rotor positions and operating conditions, the evaluation unit automatically selects appropriate gain values from the gain adjustment register, ensuring optimal measurement precision across different air gap conditions without causing sensor saturation.
Solution Approach 2:
The system changes the gain parameter dynamically based on detected operating conditions. The evaluation unit modifies the gain value stored in the gain adjustment register according to the specific actuator embodiment and operating state, allowing the system to maintain high measurement precision across varying conditions without fixed compromise values.
4Measurement precision
If a small slope is used for gain setting, then the measurement precision is improved for weak signals, but the reliability deteriorates due to poor signal-to-noise ratio
Solution Approach 1:
The patent implements dynamic gain adjustment that adapts to the specific actuator configuration. By detecting rotor positions and operating conditions, the evaluation unit automatically selects appropriate gain values from the gain adjustment register, ensuring optimal measurement precision across different air gap conditions without causing sensor saturation.
Solution Approach 2:
The system changes the gain parameter dynamically based on detected operating conditions. The evaluation unit modifies the gain value stored in the gain adjustment register according to the specific actuator embodiment and operating state, allowing the system to maintain high measurement precision across varying conditions without fixed compromise values.
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 flexible and reliable gain setting for magnetic field sensors, correcting static tolerances and adapting to changes over time, ensuring accurate position determination of the rotor in electric motors, while reducing costs and improving functional safety by eliminating the need for two microcontrollers.
Implementation Method 1
a magnetic field sensor (9) designed as a rotor position sensor for determining a position of a rotor (7) of the electric motor (4) from a magnetic field signal from the magnetic field sensor (9)
Data Source
AI summary
A method for setting a gain of a magnetic field sensor includes providing the magnetic field sensor and an evaluation unit on a same printed circuit board, generating a magnetic field signal with the magnetic field sensor, transmitting the magnetic field signal to the evaluation unit, evaluating the magnetic field signal with the evaluation unit, and transmitting a signal for setting the gain from the evaluation unit to the magnetic field sensor. In an example embodiment, the magnetic field sensor is a rotor position sensor of an electric motor.