Electric Machine Controller Calibration for Harmonic Ripple Reduction
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Solution Overview
Problem
Existing methods for calibrating electric machine controllers require significant application or calibration effort on a test bench, often involving costly torque sensors, to determine parameters for current harmonics that minimize mechanical and acoustic oscillations, which is not feasible in many applications due to the absence of standard torque sensors.
Innovation Solution
A method involving specifying a sinusoidal phase current and superimposing test signals with harmonic oscillations to detect response signals, repeating with varying amplitudes and phases to ascertain a calibrated signal that minimizes mechanical oscillations, allowing for calibration without external sensors or test benches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque sensors are used to measure torque ripple for calibration, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical torque sensor measurement system with an electrical measurement system. Instead of using a torque sensor to directly measure torque ripple, the method uses current sensors to measure phase currents and calculates torque ripple indirectly through mathematical processing of current signals and machine parameters, thereby eliminating the need for expensive torque sensors.
Solution Approach 2:
The patent introduces mathematical models and calculation algorithms as intermediaries between the measurable quantity (phase current) and the target quantity (torque ripple). By using machine parameters and current signals as intermediaries, the system can derive torque ripple information without direct mechanical measurement.
2Manufacturing precision
If extensive calibration on test benches is performed to determine current harmonic parameters, then manufacturing precision is improved, but loss of time and productivity decrease
Solution Approach 1:
The patent performs preliminary characterization of the electric machine by determining machine parameters (such as inductances, resistances, and magnetic characteristics) during the manufacturing process or initial setup. These pre-determined parameters are then used in subsequent operational calibration, reducing the need for extensive real-time test bench calibration.
Solution Approach 2:
The calibration system uses the electric machine's own operational data (phase currents, voltages, and performance characteristics) to automatically determine and optimize current harmonic parameters. The machine essentially calibrates itself by processing its own operational information, eliminating the need for external test bench equipment and extensive manual calibration procedures.
3Measurement precision
If high sensitivity torque sensors are used to access low torque ripple, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces high-sensitivity mechanical torque sensors with electrical current measurement systems. By measuring phase currents with standard current sensors and using mathematical processing to extract torque ripple information, the system achieves the same measurement precision without requiring expensive, high-sensitivity mechanical sensors.
Solution Approach 2:
The patent shifts the measurement from the mechanical torque dimension to the electrical current dimension. Instead of measuring torque directly in the mechanical domain, the system measures electrical currents and transforms this information into torque ripple data through mathematical relationships, effectively changing the measurement dimension.
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 efficient calibration of electric machine controllers by minimizing mechanical and acoustic oscillations through a self-learning process, reducing metrological and computational effort, and allowing for recalibration based on operating conditions, thus optimizing drivetrain operation without the need for expensive sensors or test benches.
Implementation Method 1
superimposing the first signal with a test signal to generate at least one harmonic oscillation having a predetermined excitation amplitude and/or phase position relative to the phase current
Implementation Method 2
detecting a response signal resulting from the superposition of the phase current and the harmonic oscillation, in particular its response amplitude
Data Source
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.