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

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 of resolver true electrical position. This affects the field orientation control in machines, leading to oscillations in currents and electromagnetic torque. This paper 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. A novel method to mitigate the aforementioned dc-link oscillations by estimating the position error of any desired harmonic is set forth. The method is validated by simulated and experimental results.