Vibration suppression of induction-motor-driven hybrid vehicle using wheel torque observer

The authors describe the vibration phenomenon occurring in indirect field-oriented control or vector control when induction motors drive inertia load through a spring under overload at high speed. The target system of this study is a hybrid vehicle consisting of a front engine-driven system and two rear motor-driven systems, which are designed to improve the driving stability. In this vehicle, violent vibrations occur when the induction motors drive under strict conditions of overload at high speed. The stability analysis and a mechanical system, revealed that the vector control system is essentially unstable under extreme overload and demagnetization when the induction motor loads the power train. Therefore, suppression of vibrations was attempted using an observer for estimating wheel torque and a regulator for state feedback from the outside of the vector control system. These methods suppressed the vibration well enough to drive under overload at high speed