Sensorless Control of High-Speed PMSM Based on Cascade High-Order Extended State Observer for Flywheel Energy Storage System

Sensorless control of high-speed permanent magnet synchronous motors (HSPMSMs) using the conventional extended state observer (ESO) exhibits limitations in accurately estimating the back electromotive force (BEMF). Such phase delays adversely affect the performance and dynamic response of HSPMSMs. To address this issue, a cascade high-order extended state observer (CHESO) is proposed to enhance position estimation and speed control of HSPMSMs. The effectiveness of the CHESO in extending the observation bandwidth and improving control accuracy is demonstrated. In the proposed two-level CHESO architecture, the BEMF is accurately estimated at the first level, while position, load torque, and uncertain disturbances are concurrently estimated at the second level. Subsequently, the estimated disturbances and load torque are employed in an adaptive feedforward control strategy to enhance the dynamic performance and anti-disturbance capability of the HSPMSM control system. Compared to the conventional ESO, the proposed CHESO minimizes position estimation errors and improves the estimation accuracy of high-speed regions, as verified by experimental results.