Disturbance Rejection of IPMSM Drives by Simplified Taylor Series-Based Near Optimal Control Scheme in Wide Speed Range

This paper proposes a simplified near optimal control (NOC) scheme to reject the disturbances of interior permanent magnet synchronous motor (IPMSM) drives by minimizing the complex calculations in the Taylor series method required for solving the state-dependent Riccati equation (SDRE). Since the speed tracking performance of an IPMSM can be significantly degraded in the presence of the disturbances owing to the practical factors (e.g., external load torque, parameter uncertainties, and so on), an SDRE-based near optimal disturbance observer (NODO) is designed to accurately estimate and reject the disturbances associated with the speed and current in the feedforward control. The state-dependent coefficient matrices of the IPMSM are rearranged in the controller and observer to minimize the complex offline calculations of the Taylor series method used to solve the SDRE. By significantly simplifying the calculations, the proposed SDRE-based NOC scheme can be efficiently applied to the IPMSM drives. To verify the precise and robust control performance of the proposed NODO-based near optimal speed controller, experiments are conducted via a prototype IPMSM drive system with a TI-TMS320F28335 DSP under different disturbances. Finally, the comparative experimental results with the conventional NOC are presented under load change and wide speed range conditions.