Full-Speed-Range Sensorless Direct Torque Control of a Two-Level Interior Permanent Magnet Synchronous Motor Drive Using Hybrid High-Frequency Injection Model Reference Adaptive Control Estimation

This work develops a hybrid sensorless control scheme for a two-level voltage-source-inverter (VSI)-fed interior permanent magnet synchronous motor (IPMSM) operating under constant-switching-frequency direct torque control (DTC). It combines a stator-current model-reference adaptive control (MRAC) estimator with high-frequency signal injection to secure reliable speed and position estimation over the entire operating range—including standstill and low speed, where back-EMF (electromotive force)-based MRAC breaks down. The MRAC estimator employs a parallel adjustable stator current model driven by a cross-product-error PI adaptation law for accurate tracking from medium to high speed, while at low speed, a high-frequency (HF) carrier superimposed on the reference flux exploits rotor saliency independently of the back-EMF magnitude. The principal novelty is a hysteresis-based, debounced switching logic that hands control authority between the two estimators without disturbance; it is exercised at staged low-speed set-points (20 and 30 rad/s) before transferring to the rated 52.38 rad/s reference, yielding bump-free transitions free of sustained torque or speed error. The estimator is embedded in a modified six-sector switching-table DTC that uses a carrier-intersection torque comparator and active–passive vector pairing at a fixed 2 kHz switching frequency, together with a maximum-torque-per-ampere (MTPA) flux-reference generator that curtails copper loss. The scheme is verified by processor-in-the-loop (PIL) testing on a TI F280039C C2000 LaunchPad at a 50 µs control step, with the controller compiled through Embedded Coder and run in closed loop against a Simulink plant model at a 150 V DC link, confirming stable torque regulation, phase currents contained within a ±20 A envelope, and practical deployability for encoder-free EV (electric vehicle) traction.