Magnetic Angle Sensor Interference Compensation
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Solution Overview
Problem
Magnetic angle sensors in electrical machines are sensitive to interfering magnetic fields, leading to errors in rotor angle measurement due to current interference and misalignment, which existing methods fail to adequately compensate.
Innovation Solution
A method that estimates and corrects current and misalignment errors in the measured angle signal of a magnetic angle sensor using a microcontroller, allowing for accurate calculation of the rotor angle by processing the sensor signals through digital filtering and error estimation, thereby compensating for interference and ensuring precise rotor position determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic angle sensors are used for rotor position detection, then cost is reduced and accuracy is improved, but the sensors become sensitive to interfering magnetic fields from live conductors and permanent magnets
Solution Approach 1:
The patent applies this principle by using the interfering magnetic fields from phase currents not as unwanted noise but as useful information. The method measures the phase currents and calculates their magnetic field contribution, then subtracts this calculated interference from the raw sensor signal to extract the true rotor position. This converts the harmful interference into a compensable parameter that improves measurement accuracy.
Solution Approach 2:
The patent introduces an intermediary calculation model that represents the magnetic field contribution of phase currents. This mathematical model acts as a mediator between the raw sensor signal and the corrected rotor position, allowing the system to separate the useful signal from the interfering components without requiring physical shielding or additional sensors.
2Reliability
If existing compensation methods are used, then some interference is reduced, but current errors up to 400 A and misalignment errors cannot be adequately compensated
Solution Approach 1:
The patent applies this principle by dynamically adjusting the compensation based on operating conditions. The method calculates the magnetic field contribution of phase currents in real-time and adapts the compensation amount according to the actual current magnitude and sensor misalignment parameters. This allows the system to maintain high accuracy across a wide range of operating conditions including high currents up to 400 A and various misalignment scenarios.
Solution Approach 2:
The patent implements feedback by continuously monitoring the phase currents and using this information to adjust the compensation applied to the sensor signal. The system creates a closed-loop compensation mechanism where the calculated current interference is fed back into the signal processing chain to correct the rotor position measurement, ensuring sustained accuracy under varying load conditions.
3Measurement precision
If complex compensation algorithms are applied, then measurement accuracy is improved, but computational time increases
Solution Approach 1:
The patent replaces complex iterative mathematical optimization algorithms with a direct analytical calculation approach. Instead of using computationally intensive methods to separate signal components, the invention uses a closed-form mathematical model that directly calculates the current interference based on phase current measurements and subtracts it from the sensor signal in a single computational step, dramatically reducing processing time.
Solution Approach 2:
The patent segments the signal processing into distinct independent calculations: measuring phase currents, calculating their magnetic field contribution, measuring the sensor signal, and subtracting the interference. This segmentation allows each step to be computed efficiently using simple arithmetic operations rather than requiring complex integrated algorithms, reducing overall computational burden while maintaining accuracy.
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 method achieves an error in rotor angle position of less than 1° at high speeds and up to 18,000 rpm, with angular velocity error less than 10 rpm/s, and can compensate for measurement errors up to 20%, radial misalignment of 1 mm, axial misalignment of 5 mm, and current errors of 400 A, while being computationally efficient with a measurement time of 100 μs.
Implementation Method 1
a magnetic angle sensor (12) arranged on the stator (12) opposite the rotor (16)... A magnetic field that changes over time is for example able to be generated in the angle sensor
Implementation Method 2
An angle sensor utilizes what is known as the magnetoresistive effect, as occurs for example in the permalloy alloy. In the case of this effect, the resistance changes as a function of the direction of the changing induced magnetic field
Data Source
AI summary
A method for compensating interference in a measured angle signal of a magnetic angle sensor of an electrical machine, wherein the method includes: receiving a measured angle signal, estimating a current error and/or a misalignment error in the measured angle signal, calculating an expected rotor angle from the measured angle signal, taking into account the estimated current error and/or the estimated misalignment error, such as during operation of the electrical machine. The present invention furthermore relates to a microcontroller for calculating interference in a measured angle signal of a magnetic angle sensor of an electrical machine, to an electrical machine having a magnetic angle sensor and a microcontroller and to a computer program product.