State and disturbance estimator based feedback controller synthesis for hybrid electric vehicle

The development of an output feedback controller (OFC) for a hybrid electric vehicle (HEV) is presented in this paper. The light-weighted DC motor-driven model of HEV is considered which includes a high degree of nonlinearity as uncertainty. The nonlinearity, uncertainty, and non-assessable states of the HEV plant model are estimated using a state and uncertainty estimator (SUE). The proposed controller is designed for speed control of the motor for optimal operation of HEV to meet the model range specifications based on SUE and output feedback. A suitable reference trajectory has been obtained for a smooth tracking response of motor speed. The uncertainty considered in this paper is significantly large and does not require satisfying the constraints (bounded/finite derivative to be zero, etc). The estimator-based OFC is synthesized for the attenuation of the effect of nonlinearity and uncertainty to stabilize the HEV. For the analysis of stability, sufficient conditions for the synthesis of OFC have been obtained using the Lyapunov theory and linear matrix inequality approach. The simulation study has been done to show the efficacy of the proposed OFC control scheme. The performance of the proposed scheme has been analyzed by a comparative evaluation with the existing control schemes in terms of tracking performance, lesser tracking error, bounded control input under actuator limit, attenuation of the effect of nonlinearity and uncertainty, etc. Finally, it is concluded that the HEV performance using the proposed control scheme has been enhanced in comparison with existing schemes.