Encoderless Five-phase PMa-SynRM Drive System Based on Robust Torque-speed Estimator with Super-twisting Sliding Mode Control

In this paper, a robust torque speed estimator (RTSE) for linear parameter changing (LPC) system is proposed and designed for an encoderless five-phase permanent magnet assisted synchronous reluctance motor (5-phase PMa-SynRM). This estimator is utilized for estimating the rotor speed and the load torque as well as can solve the speed sensor fault problem, as the feedback speed information is obtained directly from the virtual sensor. In addition, this technique is able to enhance the 5-phase PMa-SynRM performance by estimating the load torque for the real time compensation. The stability analysis of the proposed estimator is performed via Schur complement along with Lyapunov analysis. Furthermore, for improving the 5-phase PMa-SynRM performance, five super-twisting sliding mode controllers (ST-SMCs) are employed with providing a robust response without the impacts of high chattering problem. A super-twisting sliding mode speed controller (ST-SMSC) is employed for controlling the PMa-SynRM rotor speed, and four super-twisting sliding mode current controllers (ST-SMCCs) are employed for controlling the 5-phase PMa-SynRM currents. The stability analysis and the experimental results indicate the effectiveness along with feasibility of the proposed RTSE and the ST-SMSC with ST-SMCCs approach for a 750-W 5-phase PMa-SynRM under load disturbance, parameters variations, single open-phase fault, and adjacent two-phase open circuit fault conditions.