## 3 Results
### Results for the Designed BLDC Motor
#### 3.1.1 Calculated Parameters and Performance  
At the beginning of the work, machine parameters were determined; according to that, the machine flux, current, and air-gap flux density were calculated. In addition, the machine torque and speed are critical for the flight dynamics of UAVs. Because of this, these values were observed and collected during the simulation. After the simulation of the designed machine, the results showed that the simulation results were close enough to the calculated parameters. In Table 7, the calculated and simulated parameter results are shown. In addition, dynamic simulation results containing the speed, current, and torque with respect to time are presented in Figures 7-9. \begin{table}
\begin{tabular}{c c} \hline \hline
**Variable** & **Value** \\ \hline Nominal Voltage & 345 [V] \\ Cell Capacity & 78 [Ah] \\ Cell Configuration & 96S12P \\ Maximum Continuous Discharge Power & 40 [kW] \\ Battery Weight & 70 [kg] \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Specifications of the newly created battery model. Figure 6: Combined model for flight simulation. Figure 8: Torque\(-\) time response of the designed BLDC motor. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Variable** & **Calculated Value** & **Simulation Results** \\ \hline Flux [mWb] & 14.49 & 13 \\ Current [A] & 107.52 & 100.6 \\ Torque [Nm] & 152 & 162 \\ Air-Gap Flux Density [T] & 0.8 & 0.76 \\ Flux Density in stator Yoke [T] & 1.4 & 1.329 \\ Flux Density in stator Tooth [T] & 1.6 & 1.623 \\ Current Density [A/mm\({}^{2}\)] & 5.6 & 5.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Comparison of the calculated and simulated values. Figure 7: Current\(-\) time characteristics of the designed BLDC motor. The designed machine's torque and current with respect to time are presented in Figures 7 and 8; similarly, they were obtained in the dynamic simulation. The dynamic simulation was conducted with a simple drive circuit that was based on the rotor position while creating a switching signal and aiming to observe the machine characteristics under the determined torque load and inertia. These results are compared with calculated parameters that were determined at the beginning of the work, as shown in Table 7.  
The magnetic flux density is another critical parameter that affects machine performance in terms of thermal effects, loss, and saturation issues. The values of magnetic flux densities were also matched with the calculated parameters, as shown in Table 7.  
Another parameter that affects machine performance is the cogging torque. To reduce the cogging torque values in the designed machine, a skewed design was implemented in the rotor. The rotor skew angle was set to 1.714. The skewed and initial condition effects are shown in Figure 9. With a skewed-angle rotor, the cogging torque was significantly reduced. To measure machine performance, the correlations between the torque, power, and speed were observed. A graphic of the power and speed is shown in Figure 10. In the related graphic, the power values with respect to speed are shown with the advance angle of electric phases. In a related study, a phase advance angle of 0 to 60 with an incremental rate of 10 degrees was considered and referenced as 0. According to the related graphic, the power and speed values matched with the initial design values. The torque-speed characteristic is another important parameter because it is a crucial parameter for propulsion systems. Torque values and machine speed affect thrust force, and they are important for UAV performance. As shown in Figure 11, the torque and speed values matched with the calculated values at the beginning of the study. The same situation  
Figure 10: Power\(-\)speed values with respect to advance angles. Figure 9: Cogging torque with skewed and normal rotors. occurred for the advance angle of the electrical phase with power-speed characteristics shared before.