Rotor Position Sensing with Dynamic Hall Signal Normalization
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Solution Overview
Problem
The precision of rotor position estimation in rotary electric machines is compromised by amplitude gaps between Hall effect sensors, leading to harmonic generation in control loops, which are not robust across the machine's operating range, especially with temperature changes.
Innovation Solution
A dynamic normalization circuit is introduced to process signals from position sensors by demodulating and normalizing them based on the amplitude of the first harmonic, ensuring consistent harmonic amplitude, thereby reducing or eliminating harmonics and improving signal precision within the control loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fixed correction coefficients are assigned to the transformation matrix to correct amplitude gaps between sensors, then the amplitude uniformity is improved at a specific operating point, but the robustness across the entire operating range deteriorates
Solution Approach 1:
The patent transforms the static correction approach into a dynamic one by continuously adapting the normalization coefficients based on real-time operating conditions. The correction values are no longer fixed but are dynamically adjusted according to temperature, rotational speed, and other operating parameters, allowing the system to maintain optimal performance across the entire operating range rather than being optimized for a single point.
Solution Approach 2:
The patent changes the correction parameters from fixed values to variable values that adapt to operating conditions. By monitoring temperature, rotational speed, and other parameters, the system adjusts the normalization coefficients accordingly, transforming the correction mechanism from a static parameter set to a dynamic parameter set that responds to environmental and operational changes.
2Measurement precision
If multiple Hall effect sensors are used to determine rotor position, then the measurement coverage is improved, but the signal amplitude inconsistency between sensors worsens
Solution Approach 1:
The patent applies individual normalization to each sensor signal based on its specific characteristics. Rather than applying a uniform correction to all sensors, the system determines separate normalization coefficients for each sensor, accounting for local variations in sensor performance, positioning, and electrical characteristics, thereby maintaining signal consistency across multiple sensors.
Solution Approach 2:
The patent implements a feedback mechanism where the actual sensor signals are monitored and used to dynamically adjust the normalization coefficients. The system continuously evaluates the signal amplitudes from multiple sensors and adjusts the correction factors accordingly, creating a closed-loop system that maintains signal consistency through real-time feedback and adaptation.
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 enhances the precision of rotor position signals, improving control loop performance and robustness across varying operating conditions, including temperature changes and rotational speeds.
Implementation Method 1
demodulate each signal originating from a position sensor by the image of the signal representative of the position of the rotor
Implementation Method 2
The low-pass filter can have a cutoff frequency of between 0.3 Hz and 50 Hz for a magnetic target borne by the rotor with eight pairs of poles
Implementation Method 3
to use a plurality of Hall effect sensors, the signals of which are processed
Data Source
AI summary
Device for determining the angular position of a rotor of a rotary electric machine on the basis of signals delivered by a plurality of position sensors, including a circuit producing a control loop for estimating position of the rotor, delivering at output a signal representative of the position, and a circuit for dynamic normalization by the amplitude of the first harmonic of each signal originating from a position sensor. The circuit receives as input each signal originating from a position sensor, and at least one image of the signal representative of the position of the rotor and is configured to demodulate each signal by the image of the signal, determine, at the end of this demodulation, amplitude of the first harmonic of this signal originating from a position sensor, and normalize each signal by dividing it by the amplitude of the first harmonic of the previously determined signal.