Electric Machine Controller Calibration for Torque Ripple Without Sensors
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Solution Overview
Problem
Existing methods for calibrating control systems of electrical machines require significant application and calibration effort, especially when precise model descriptions are lacking, and often rely on expensive torque sensors, which are not standard in many applications.
Innovation Solution
A method involving specifying a sinusoidal phase current signal, superimposing test signals to generate harmonic oscillations, detecting response signals, and determining a calibrated signal to minimize mechanical vibrations and noise by analyzing a response surface constructed from these signals, allowing for self-calibration without external sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque sensors are used for calibration, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses current sensors and mathematical models as intermediaries to indirectly measure torque ripple, avoiding the need for direct torque sensor measurement. The control system superimposes test signals on phase currents, measures the resulting voltage responses through existing current sensors, and calculates torque ripple characteristics through mathematical evaluation, thereby achieving precise measurement without expensive torque sensors.
Solution Approach 2:
The patent replaces the mechanical torque sensor measurement system with an electrical measurement and calculation system. Instead of mechanically measuring torque ripple with a torque sensor, the system uses electrical test signals superimposed on phase currents, measures voltage responses through electrical sensors, and computes torque ripple characteristics through mathematical evaluation, substituting mechanical measurement with electrical and computational methods.
2Manufacturing precision
If iterative parameter determination is performed, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The patent performs preliminary determination of current harmonic parameters by superimposing test signals with predetermined excitation amplitudes and phase positions, and evaluating the resulting response surfaces to identify minima before actual operation. This preliminary calibration establishes optimal parameters in advance, avoiding the need for time-consuming iterative adjustments during manufacturing or operation, thereby reducing calibration time while maintaining precision.
3Ease of manufacture
If model-based parameter determination is used, then ease of manufacture is improved, but measurement precision may worsen
Solution Approach 1:
The patent implements feedback by measuring the actual response signals from the electrical machine during test signal superposition, evaluating the response surface based on these measured values, and using the identified minima to determine optimal current harmonic parameters. This feedback loop ensures that the model-based determination is grounded in actual machine characteristics, maintaining high measurement precision while simplifying the manufacturing process.
Data Source
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AI summary
The invention relates to a method (400) for calibrating a controller of an electric machine (120). The method comprises the following steps: specifying (410) a first signal (S_1) for generating a sinusoidal phase current for energising a winding of an electric machine (120); superposing (420) the first signal (S_1) with a test signal (S_Test_i) in order to generate a harmonic oscillation with a predetermined excitation amplitude and/or phase position relative to the phase current, which harmonic oscillation superposes the phase current; detecting (430) a response signal (S_Antw_i), resulting from the superposition of the phase current and the harmonic oscillation, by means of a sensor (130); determining (450) a calibrated signal (S_kal) for generating a harmonic oscillation with a predetermined excitation amplitude and a phase position relative to the phase current on the basis of a determined minimum of a response plane (A_Antw); operating (460) the controller (110) of the electric machine (120) on the basis of the determined minimum.