Short Convergence Time Super-Twisting Sliding Mode Speed Control of Permanent Magnet Synchronous Motor

One of the most popular motors for precise control applications, such as electric vehicles, is the permanent magnet synchronous motor (PMSM). Under harsh conditions, PMSM and its drives are expected to provide robust control response against internal and external disturbances. Conventional controllers used in the vector control method have difficulty providing superior control responses due to the nonlinear structure of the PMSM. Although sliding mode control is a good control method to fulfill these control requirements, it has a chattering effect due to high-speed switching phenomenon. To reduce this effect and to obtain a better dynamic response, super-twisting sliding mode control (ST-SMC) is one of the control method candidates. In the classical ST-SMC control method, since the sliding surface consists of error or error-integral of the error, the finite time convergence to the equilibrium point is not fast enough. In this study, a new nonlinear sliding surface is designed in the ST-SMC controller for speed control of PMSM. In addition, equivalent control terms and an error-dependent exponential term are added to the control input to speed up the output response. In this way, the ST-SMC algorithm is experimentally applied to control the speed of the PMSM under harsh operating conditions with reduced chattering, shortened convergence time, and increased robustness against internal and external disturbances. The experimental implementation of the designed controller is carried out on a 400 W PMSM motor test setup. The superiority of the proposed control algorithm is comparatively demonstrated under operating conditions such as step speed reference and load torque.