## 3 Results
### Measurements with External Load  
The same measurements were repeated in the motor brake load condition. The waveforms for the various control methods in the loaded condition are shown in Figure 7. \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Control Mode**} & \multicolumn{2}{c}{**Energy Efficiency**} \\ \cline{2-3}  & \multicolumn{2}{c}{**E\({}_{\text{SF}}\)**} \\ \cline{2-3}  & **Transient State Average** & **Steady State Average** \\ \hline V/f & 0.34 & 0.34 \\ VFC without encoder & 0.33 & 0.33 \\ VFC n-control & 0.66 & 0.66 \\ CFC & 0.45 & 0.45 \\ CFC with torque control & 0.47 & 0.47 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Characteristics of the energy efficiency E\({}_{\text{SF}}\) in the steady state (without an external load). Figure 7: Characteristics of the output current intensity (I\({}_{\text{O}}\)) and the active current intensity (I\({}_{\text{A}}\)) in various control modes (with the external load): (**a**) V/f, (**b**) VFC without an encoder, (**c**) VFC n-control, (**d**) CFC, (**e**) CFC with torque control. Figure 8 shows a comparison of the load state currents for various control modes. There is a characteristic current peak visible in the scalar mode due to its lack of precision in the control over the motor dynamics. Table 11 shows the peak values of the output current (I\({}_{\text{O}}\)) and the active current (I\({}_{\text{A}}\)) of the frequency converter in a transient state in the loaded condition. Table 12 shows the characteristics of the output current (I\({}_{\text{O}}\)) and the active current (I\({}_{\text{A}}\)) in a steady state in the loaded condition. Table 13 shows the time characteristics of the output current (I\({}_{\text{O}}\)) and the active current (I\({}_{\text{A}}\)) in the transient state in the loaded condition. The comparison of the rotational speed (n\({}_{\text{A}}\)) for various control modes is presented in Figure 9.  
Table 14 shows the values of the overshoot of the rotational speed in the transient state in the loaded condition. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Control Mode**} & \multicolumn{4}{c}{**Current Intensity [A]**} \\ \cline{2-5}  & \multicolumn{2}{c}{**I\({}_{\text{O}}\)**} & \multicolumn{2}{c}{**I\({}_{\text{A}}\)**} \\ \cline{2-5}  & **[A]** & **[\%] * & **[A]** & **[\%] * \\ \hline V/f & [A] & [\%] * & [A] & [\%] * \\ VFC without encoder & 1.64 & 91.10 & 1.44 & 80.00 \\ VFC n-control & 1.55 & 86.10 & 0.91 & 50.50 \\ CFC & 1.97 & 109.40 & 0.86 & 47.70 \\ CFC with torque control & 1.25 & 69.40 & 1.07 & 59.40 \\ \hline \hline \end{tabular}
* Value related to the full range of the motor rated current (I\({}_{\text{O}}\)).  
\end{table} 
Table 11: Peak values of the output current (I\({}_{\text{O}}\)) and the active current (I\({}_{\text{A}}\)) of the frequency converter in a transient state (with the external load). Figure 8: Comparison of: (**a**) output current intensity values (I\({}_{\text{O}}\)) for various control modes, (**b**) active current intensity values (I\({}_{\text{A}}\)) for various control modes. \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Control Mode**} & \multicolumn{2}{c}{**Tome [ms]**} \\ \cline{2-3}  & **to\_S** & **t\_A,S** \\ \hline V/f & 200.00 & 176.00 \\ VFC without encoder & 199.00 & 114.00 \\ VFC n-control & 94.00 & 190.00 \\ CFC & 336.00 & 212.00 \\ CFC with torque control & 330.00 & 228.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 13: Time characteristics of the output current (I\({}_{\text{O}}\)) and the active current (I\({}_{\text{A}}\)) in the transient state (with the external load).