# Super Twisted Sliding Mode Observer for Enhancing Ventilation Drive Performance
## 3 Experimental Setup and Results
### Results and Discussion  
In the following cases, the drive was equipped with a sensorless STSMO, where the estimated speed was used for speed control, and the speed sensor was employed primarily for performance assessment. The stability and efficacy of STSMO-based speed observers were evaluated through experiments conducted at low and near-zero speeds, as well as across a broad range of rotor speeds. * Case 1: Sensorless vector control encounters challenges at near-zero speed during no-load operation. Figure 4a compares the performance of the traditional MRAS with the STSMO-based MRAS. Notably, the STSMO-based MRAS demonstrates stable steady-state performance under the given conditions. * Case 2: This scenario examines the system's response to a predetermined reference speed, which challenges the drive's ability to maintain field orientation at low stator frequencies. The corresponding results are illustrated in Figure 5. As depicted in Figure 5b, the standard SMO demonstrates unsteady performance, with fluctuations  
Figure 3: Experimental setup for the speed control of an IMD using the STSMO. Figure 2: Control strategy for the sensorless vector control of an IMD using the proposed observer. observed between \(-140\) and \(130\) rpm. In contrast, the STSMO-based MRAS achieves stable operation without oscillations (Figure 5a). * Case 3: This scenario evaluates the encoderless drive's performance between reference speeds of \(345\) rpm and \(-200\) rpm. The results for the proposed model are depicted in Figure 6a, while Figure 6b presents the results for the traditional SMO technique. Compared to the traditional SMO with a PI controller, the proposed STSMO-based MRAS achieves consistent performance with minimal steady-state error. Figure 4: (**a**) Sensorless control performance using the proposed STSMO model in the speed range of \(-35\) rpm to \(5\) rpm. (**b**) Sensorless control performance using the conventional SMO model in the speed range of \(-35\) rpm to \(5\) rpm. (**c**) Change of the flux during the change of the speed from \(-35\) rpm to \(5\) rpm in proposed method. The results indicate that the STSMO-based speed estimator for the ventilation system drive and control algorithm demonstrates improved performance in the low- and medium-speed operational ranges. The efficacy and reliability of the proposed algorithm are validated using various operational cases. Figure 5: (**a**) Sensorless control performance using the proposed STSMO model in the speed range of \(-140\) to \(130\) rpm. (**b**) Sensorless control performance using the conventional SMO model in the speed range of \(-150\) to \(120\) rpm. (**c**) Change of the flux during the change of the speed from \(-35\) rpm to \(5\) rpm in proposed method. Figure 7 clearly shows that the proposed method has a low THD value of current profile. Table 2 shows the Gain sweep analysis at a\({}_{2}\) = 500, 1000, 1500, and 2000, and it clearly demontrates that a\({}_{2}\) = 1000 has low convergence time and chattering index. Figure 6: (**a**) Sensorless control performance using the proposed STSMO model in the 345 rpm and \(-200\) rpm speed range. (**b**) Sensorless control performance using the conventional SMO model in the 345 rpm and \(-200\) rpm speed range. (**c**) Change of the flux during the change of speed from 345 rpm and \(-200\) rpm in the proposed method. Table 3 compares the performance of the proposed model with that of other speed estimators. This investigation focuses on the proposed model's ability to track speed at low operating speeds. The STSMO-based drive outperforms the previously proposed speed estimators in terms of complexity, robustness, and the minimization of maximum speed estimation error. Consequently, the STSMO is more efficient and reliable than alternative approaches for low-power, high-performance, and cost-effective industrial applications. Our findings conclude that the STSMO model outperforms other speed observers in the low- and medium-speed ranges.