## 5 Experimental Results and Discussion  
The model parameters of the SPMSM are listed in Table 4.  
\begin{table}
\begin{tabular}{c c} \hline
**Parameter** & **Value** \\ \hline rated power & 4 kW \\ rated speed & 2000 rpm \\ max power & 5 kW \\ poles & 10 \\ phase resistance & 0.12 \(\Omega\) \\ phase inductance & 1.67 mH \\ DC bus voltage & 270 V \\ stator outer diameter & 150 mm \\ Stator inner diameter & 100 mm \\ axial length & 68 mm \\ PWM frequency & 5 kHz \\ \hline \end{tabular}
\end{table}
Table 4: Model parameters of SPMSM.  
Figure 9: Flowchart of the golden section search procedure.  
To verify the proposed control strategy, the experiment is implemented by a PMSM test platform, which is shown in Figure 10.  
The efficiency of the PMSM in SPWM is shown in Figure 11.  
Figure 11: _Cont._  
Figure 10: PMSM test platform: (a) Experimental platform; (b) Block diagram of test platform.  
Figure 11a,b show the efficiency of the PMSM using the traditional \(i_{d}=0\) control and proposed MEPT control, respectively, where the maximum efficiency of the PMSM using \(i_{d}=0\) control is 94%. It can be seen that the MEPT control can broaden the high-efficiency field of the PMSM and obtain a higher efficiency in each operation condition of the PMSM. It is shown in Figure 11c that the efficiency can be increased in the whole operation range of the PMSM and the maximum efficiency enhancement is 0.36%.  
The efficiency of the PMSM in SVPWM is shown in Figure 12.  
The efficiency of the PMSM using the traditional \(i_{d}=0\) control and proposed MEPT control is shown in Figure 12. From Figure 12a,b, the MEPT control can also enhance the high-efficiency field of the PMSM. Compared with the efficiency of the PMSM using the \(i_{d}=0\) control, Figure 12c shows that the efficiency of the PMSM is increased by the MEPT control in the whole operation range, and the maximum efficiency enhancement is 0.51%.  
From Figures 11 and 12, it can be seen that the operation speed range is different between SPWM and SVPWM, because the DC bus voltage utilization of SVPWM is higher than SPWM. It can be also seen that the efficiency optimization performance of MEPT control in SVPWM is greater than the performance in SPWM.  
Figure 11: Results of the PMSM in SPWM: **(a)** Efficiency of PMSM in traditional \(i_{d}=0\) control; **(b)** Efficiency of PMSM in proposed MEPT control; **(c)** Difference of efficiency between \(i_{d}=0\) control and MEPT control.  
Figure 12: Results of the PMSM in SVPWM: (**a**) Efficiency of PMSM in traditional \(i_{d}=0\) control; (**b**) Efficiency of PMSM in proposed MEPT control; (**c**) Difference of efficiency between \(i_{d}=0\) control and MEPT control.  
It is generally observed that the MEPT control strategy can increase the efficiency performance of the PMSM in the whole operation range in both SPWM and SVPWM. For the experimental 5 kW high-efficiency PMSM, although the motor efficiency has achieved as great as 94% efficiency using the traditional \(i_{d}=0\) control, the proposed MEPT control can also enhance the motor efficiency by 0.51%. The MEPT control strategy is a fast and efficient way to increase the efficiency of the PMSM and decrease the loss of the motor system without damage to the dynamic performance in the aviation and aerospace field.