Mitigation of DC-Link Voltage Oscillations Caused by Resolver Error in an Electric Vehicle Drivetrain

Abstract

Resolvers are commonly used to measure the rotor position in motor drive applications. However, manufacturing imperfections introduce a position measurement error, which manifests itself as relatively small oscillations primarily at the fundamental and second harmonic frequencies. This affects the field orientation control in machines, leading to oscillations in currents and electromagnetic torque. This research focuses on the impact of position error in a series-hybrid drivetrain architecture. In this topology, substantial oscillations in dc-link voltage are induced, which are further exacerbated by reducing the dc-link capacitance in a bid to lower the overall inverter size and weight. This work sets forth various methods to mitigate the aforementioned dc-link oscillations based on control modifications. To this end, a linearized small-signal detailed model of the drivetrain is developed first to support the analysis of the phenomenon. The effectiveness of these techniques is validated by analytical and experimental results.