Adaptive super-twisting sliding mode observer based positionless direct torque control strategy for PMSM

A novel rotor position estimation technique utilising the super-twisting sliding mode observer (STSMO) was introduced to address diminishing reliability in position sensors of permanent magnet synchronous motors (PMSMs). A cutting-edge direct torque control (DTC) strategy for PMSM functioning without reliance on a position sensor was proposed to address the challenges of increased chattering and limited perturbation resistance resulting from fixed sliding mode parameters in standard STSMOs. This strategy employed an adaptive super-twisting sliding mode observer (ASTSMO). This method enhanced the system’s response speed and estimation accuracy by facilitating online adjustment of sliding mode coefficients. A rigorous stability analysis of the observer was presented. A hyperbolic tangent function of the segmented square root was introduced as a substitute for the conventional sign function to mitigate chattering and eliminate the need for low-pass filters and phase compensation. This approach simplified the system’s complexity while improving angle estimation accuracy, response speed, and observer stability. Additionally, a phase-locked loop (PLL) was used to estimate the rotor angle, which improved the accuracy of the rotor angle estimation. Comprehensive simulations and experimental validations demonstrated that the proposed ASTSMO could suppress system’s chattering under varying operational conditions, exhibiting superior estimation accuracy and stability compared to the traditional STSMO.