# Optimization Design and Control of Six-Phase Switched
## 5 Optimal Result and Experimental Verification  
As presented in Table 3, the ratio of stator yoke and teeth width for different designs are set between 0.89 and 0.92. Considering that the area of stator slots will be reduced if a large value of \(\lambda_{\text{hcs}}\) is selected. Thus, design 4 is selected as the final optimal solution, and \(\lambda_{\text{hcs}}\) is finally determined as 0.89 due to the manufacturing requirement. The initial and optimal values of the optimization parameters are tabulated in Table 5. It can be found that, compared with the initial design, the average toque has been improved while the toque ripple and the difference between the adjacent phase currents have been reduced after optimization.  
After the determination of the optimal design, the control angles of the SRM are divided into two groups and an asymmetric control is utilized. For the asymmetric control, it means that the windings in phases A, C, and E are conducted in advance for 5\({}^{\circ}\) (corresponding to \(\alpha_{\text{Aon}}=13^{\circ}\) in Table 5) and keep conducting for \(15.8^{\circ}\), while those in phases B, D and F phases are conducted in advance for \(5.5^{\circ}\) (corresponding to \(\alpha_{\text{Bon}}=18.5^{\circ}\) in Table 5) and keep conducting for \(15.3^{\circ}\).  
When the ratio of stator yoke and teeth width is defined as 0.89, the current and output torque under the proposed asymmetrical control (\(\alpha_{\text{Aon}}=13^{\circ}\), \(\alpha_{\text{Bon}}=18.5^{\circ}\)) and the traditional symmetric control (\(\alpha_{\text{Aon}}=13^{\circ}\), \(\alpha_{\text{Bon}}=19^{\circ}\)) methods are presented in Figure 8. In Figure 8, \(I_{\text{B1}}\), \(I_{\text{CL}}\), and \(T_{1}\) are the currents of phases B and C, and torque under the proposed asymmetric control, respectively, and \(I_{\text{B2}}\), \(I_{\text{C2}}\), and \(T_{2}\) are the currents of phases B and C, and torque under the traditional symmetric control, respectively. The difference is that, compared with the traditional symmetric control, the turn-on angle of phases B, D, and E of the proposed asymmetrical control is advanced by \(0.5^{\circ}\). Thus, the current values in these phases can be enlarged, and the torque has been improved. It can be verified in Figure 8, obtained by FEM. Compared with the traditional symmetric control, the current of phase B and the minimum value of output torque can be improved by the proposed asymmetric control.  
To validate the proposed method, the six-phase \(12/10\) SRM experimental platform based on dSPACE is constructed, as presented in Figure 9a. The rotational speed of  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \(T\) & \(T\_{  
the SRM is defined as 1000 r/min due to the accuracy of the torque and speed sensor. Figure 9b,c present the torque and phase currents based on symmetrical control and asymmetric control, respectively. Channels 1, 2, and 3 are output torque and currents of phases B and C, respectively. As presented in Figure 9b,c, the peak value of torque for symmetrical control and asymmetric control are similar, and the valley value of torque can be enhanced through asymmetric control. Moreover, the phase current is more symmetrical for asymmetric control.  
Figure 8: Comparison of (**a**) phase currents and (**b**) torque between the proposed asymmetric and the traditional symmetric control methods, where subscripts 1 and 2 represent the proposed asymmetric and the traditional symmetric methods, respectively.  
Figure 9: Experimental platform and results. (**a**) Test platform, (**b**) traditional symmetrical control, and (**c**) proposed asymmetric control.