Electric Motor Position Sensor Calibration via Magnetic Field Offset
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Solution Overview
Problem
Manufacturing tolerances and environmental factors introduce position indication errors in the relative positioning of the rotor and stator in electric motors, affecting optimal performance and efficiency.
Innovation Solution
A method for calibrating the position sensor by determining an offset in the indicated position of the rotor relative to the stator and controlling the angular difference between the magnetic fields based on a calibration test, ensuring accurate alignment for maximum torque production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position sensors are installed to detect rotor position, then motor performance and efficiency can be optimized, but position indication errors occur due to manufacturing tolerances and environmental influences
Solution Approach 1:
The patent changes the operational parameters of the motor by controlling the angular difference between rotor and stator magnetic fields at specific test speeds. By running the motor at a first test speed with a first angular difference and a second test speed with a second angular difference, the system creates varying operational conditions that allow detection and correction of sensor offset errors, thereby improving position indication accuracy despite manufacturing tolerances
2Measurement precision
If the angular difference between magnetic fields is controlled based on calibration test, then sensor accuracy is improved, but motor performance may be compromised during calibration
Solution Approach 1:
The calibration process is performed as a preliminary action before normal motor operation. The motor is run at test speeds with controlled angular differences to determine the optimal angular difference for maximum torque production. Once calibrated, the system stores this information and operates normally, thus sacrificing minimal performance during the initial calibration phase to achieve optimal performance afterward
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
The calibration method improves the accuracy of the position sensor, leading to enhanced motor performance and efficiency by optimizing the angle between the magnetic fields, thereby increasing torque output and reducing underperformance due to errors.
Implementation Method 1
at least one electric motor supported by the chassis and configured to convert electrical power into mechanical power. The motor has a rotor and a stator. The rotor has a magnetic field and the stator has a magnetic field.
Implementation Method 2
The rotor has a magnetic field and the stator has a magnetic field. The vehicle includes a controller controlling at least one of the magnetic field of the rotor and the magnetic field of the stator to cause an angular difference between the magnetic fields of the rotor and the stator.
Data Source
AI summary
A method is provided of calibrating a position sensor of an electric motor of a vehicle.