Holistic Consideration and Optimization of Signal Processing on a Resolver-based Rotor Position Sensor Systems in Electric Drive Trains

Abstract

Rotor position sensor systems based on resolvers are state-of-the-art in electric drive train applications, e.g. for permanent magnet synchronous motors, due to their robustness and accuracy. However, the effort for signal processing in terms of angle determination has a great complexity. Electric powertrains in automotive applications make high demands on the quality of control, which requires a precise detection of the current motor shaft position and speed. Different types of influences, like sensor signal cables, interfaces, sensor signal quantization, conditioning (e.g. filtering) and processing, cause error accumulation that interacts with the general mechanical-based disturbing factors, e.g. displacements, shock, vibrations and temperature influences. This work introduces a holistic view of the sensor signal measurement chain in terms of analysis of signal processing and error characteristics, exemplary shown on a state-of-the-art resolver system of an electric powertrain architecture. The second emphasis of this work investigates the mechanisms of signal processing and the signal processing - based effects that provoke additional errors to the measured rotor position information. The methods developed in the scope of this work are based on both, simulations of the entire electric drive train sensor system and verifications under realistic conditions by use of a highly accurate reference system on a specifically developed position sensor system test bench. The developed methods support measures of optimization to reduce the angular rotor position error of the entire sensor system based on an integration of computational and experimental investigations. As a result, causes and consequences of signal processing characteristics are pointed, which provides fundamental knowledge about the different contributing factors in terms of rotor position distortion. In this way, an approach is introduced that enables improvement and optimization of the resolver-based rotor position sensor system and thus the overall quality of control of electric traction motors even in the early design phase of electric drivetrain systems.