Super-Twisting Sliding Mode Control and Inverter Modulation in PMSM Traction Drives: A Review and Research Gaps

Permanent magnet synchronous motors (PMSMs) are widely used in electric-vehicle traction, and theirspeed controllers must tolerate parameter drift and load disturbance. Sliding mode control (SMC) is widely proposedfor this task, and its chattering has motivated boundary-layer smoothing and higher-order designs such as the SuperTwisting Algorithm (STA). This narrative review examines how the speed controller and the inverter pulse-widthmodulation (PWM) are treated together. It covers field-oriented control, classical SMC and the STA, space-vectorand discontinuous PWM (DPWM), drive-cycle and hardware-in-the-loop (HIL) validation, and five recent fractionalorder SMC studies. In the sources reviewed, four gaps emerge. No study compares the STA with PI and classicalSMC on a PMSM under a standard drive cycle. The controller studies do not vary the modulator, and the DPWMcomparisons hold switching frequency, not switching loss, constant. The fractional-order studies compare mainlywith their own integer-order counterparts or not at all. Most results are validated in simulation only. The reviewcloses with open questions for a controller–modulation comparison validated in HIL. No simulation or experimentalresults are reported here; such a comparison is under way and will be reported separately. Preprint, not peer reviewed. This article reports no original results; the comparison it motivates is ongoing.