# An Improved Hybrid Control Scheme of a Switched Reluctance Motor for Torque Ripple Reduction
## 5 Experimental Result  
The effectiveness of the proposed hybrid control scheme was evaluated through detailed experiments. In this study, a decoupled \(12/14\) bearingless SRM was chosen as the research object, which was studied in our recent project. The prototype including the stator and the rotor is shown in Figure 7, and additional details regarding the two-phase motor can be found in [44]. The torque drive control of this motor is suitable for SRMs, as the torque is independent of the suspension system. Figure 8 shows the experiment platform consisting of a prototype, a magnetic powder brake, the torque and speed sensors, controller, power supply, power converter, and oscilloscope. A prototype, a magnetic powder brake, and the torque and speed sensors are connected by two couplings. The position signal detected by the Hall sensor is input to the controller, and the controller outputs the switching signal based on the compiled control system. To verify the superiority of the hybrid control scheme (method 3),MPTC with cosine TSF using conventional LADRC (method 1) and MPTC with modified TSF using conventional LADRC (method 2) are selected for experimental comparison. Figures 9-11 show the experimental results including speed and total output torque with three MPTC schemes under different operation conditions. The speed (\(\omega\)) and total output torque are detected by a torque and speed sensor. The value of the output torque is basically equal to the sum of the predicted phase torques (\(T_{p,k+1}\)). For the fairness of the comparison of the three methods, the same control requirements are applied for each operational condition. Figure 9 shows the speed and torque results when reference speed and load torque are set as 1000 r/min and 0.4 Nm, respectively, considering that the TSF is more suitable for low- and medium-speed ranges. The startup time of method 3 is 0.11 s, whereas that of method 1 and 2 require 0.2 s and 0.18 s, respectively. The proposed scheme has a shorter dynamic response time without overshoot in the initial stage. The torque ripple ranges (the difference between the maximum and minimum torque values) of three methods are 0.47 Nm, 0.38 Nm, and 0.31 Nm, respectively. The torque ripple range of method 3 is reduced by 34% and 18% compared with method 1 and 2, respectively. The proposed method behaves well in terms of dynamic response, speed tracking, and torque ripple reduction. Figure 8: The experimental platform. Figure 7: The prototype. Figure 10: Speed and torque under speed change. (**a**) Method 1, (**b**) method 2, and (**c**) method 3. Figure 9: Speed and torque under 1000 r/min and 0.4 Nm. (**a**) Method 1, (**b**) method 2, and (**c**) method 3. Figure 10 illustrates the speed and torque results when the speed changes from 800 to 1000 rpm with a constant load torque (0.4 Nm). All three methods can reach the steady state after the speed change, and the startup time of three methods are 0.19 s, 0.18 s, and 0.14 s, respectively. Similar to the condition described above, method 3 exhibits the fastest acceleration during the startup stage. The response time of the proposed method requires 0.13 s, and methods 2 and 3 require 0.2 s and 0.17 s, respectively, when the speed change occurs at 0.25 s. The torque ripple range does not change significantly under variable speed. Moreover, the same conclusion can be obtained as that described above. Method 3 behaves well in terms of torque ripple reduction. Figure 11 shows the output speed and torque results of three control methods when load torque changes from 0.4 Nm to 0.6 Nm under 1000 r/min. The speed responses of method 1 and 2 are 0.17 s and 0.16 s, respectively, to return the reference speed, which are much slower than that of method 3 (0.13 s). The speed overshoots of the three methods are 98 r/min, 80 r/min, and 45 r/min, respectively, when load torque change occurs at 0.25 s. Moreover, the torque ripple ranges of the three methods are 0.5 Nm, 0.42 Nm, and 0.36 Nm, respectively, under 0.6 Nm.