Angular Position Sensor Error Correction for E-Machine Control
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Solution Overview
Problem
Rotating electric machine systems in vehicles face performance reduction due to errors in rotor position signals from angular position sensors like resolvers, which are exacerbated by mechanical and digital converter-related issues, leading to inadequate dynamic torque control and phase shift effects.
Innovation Solution
A system and method that dynamically corrects rotor position sensor errors by isolating harmonics related to the position sensor and digital converter, determining their magnitude and phase, and applying a total position error signal to produce a corrected output for accurate control of the rotating electric machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital filtering techniques are used to filter position sensor errors, then measurement precision may be improved, but additional undesirable phase shift and lag effects are introduced
Solution Approach 1:
The system performs preliminary characterization of the position sensor errors by measuring harmonics at different angular speeds during a calibration phase. This preliminary action creates an error model that can be applied during operation without requiring real-time filtering, thus avoiding phase shift and lag effects while still improving measurement precision
Solution Approach 2:
The patent introduces an intermediary error correction signal that is generated based on pre-characterized harmonic measurements. This intermediary signal is added to the original position sensor output to cancel out errors, providing a way to improve accuracy without using traditional filtering methods that cause phase shift and time delays
2Device complexity
If the system accepts position sensor errors, then device complexity is reduced, but performance is reduced
Solution Approach 1:
The system uses feedback from harmonic measurements taken at different angular speeds to automatically characterize and correct position sensor errors. The controller measures harmonics, determines their magnitude and phase, calculates correction signals, and applies them to the position output, creating a self-correcting system that improves reliability without requiring complex manual calibration or additional hardware
Data Source
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AI summary
A system and method for controlling a rotating E-machine and for correcting a rotational position signal output by an angular position sensor operatively connected to the E-machine in conjunction with a sensor digital converter is disclosed. For each angular operating speed of interest, a set of signals as a function of position is taken such that the harmonics (or sub-harmonics) related to the position sensor may be determined and isolated from errors due to an associated digital converter. From this information, the magnitude and phase of the position sensor harmonics is determined. The effects of the sensor digital converter (or other signal processing equipment) are then determined and accounted for, allowing the control system to apply the total position error signal to the position sensor output signal to determine a corrected position sensor signal for use in controlling the E-machine.