An Improved Cascade Extended State Observer with CVGI Based SMESO for PMSM Sensorless Control

This paper presents a sensorless drive system for permanent magnet synchronous motor (PMSM) control. Including a sliding mode extended state observer (SMESO) based on complex vector generalized integrator (CVGI) for back-EMf estimating and an improved cascade extended state observer (ICESO) for speed, position estimation. Introducing CVGI into SMESO as part of its internal dynamics can take advantage of its phase-locked characteristics to eliminate chattering without introducing phase lag. ICESO solves the high frequency noise sensitivity and peaking phenomenon of the high gain observer by reducing the gain with cascade characteristics and introducing saturation function respectively. Besides, since load torque is set as the extended state of ICESO. The load torque value is also observed and feedforward compensated to the current loop, thus improving the load robustness and dynamic performance of the motor drive system. The effectiveness and performance of the proposed schemeis verified by the simulation results.