## 3 Results
### Measurements without External Load  
The waveforms for the various control methods in the unloaded condition are shown in Figure 2.  
Figure 2: Cont. Figure 3 shows a comparison of the no-load state currents for various control modes. Figure 3: 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. Figure 2: Characteristics of the output current intensity (I\({}_{\text{O}}\)) and the active current intensity (I\({}_{\text{A}}\)) in various control modes (without an external load): (**a**) V/f, (**b**) VFC without encoder, (**c**) VFC n-control, (**d**) CFC, (**e**) CFC with torque control. Table 4 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 unloaded condition. Table 5 shows the characteristics of the output current (I\({}_{\text{O}}\)) and the active current (I\({}_{\text{A}}\)) in a steady state in the unloaded condition. Table 6 shows the time characteristics of the output current (I\({}_{\text{O}}\)) and the active current (I\({}_{\text{A}}\)) in the transient state in the unloaded condition. The comparison of the rotational speed (n\({}_{\text{A}}\)) for various control modes is presented in Figure 4. \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Control Mode**} & \multicolumn{2}{c}{**Time [ms]**} \\ \cline{2-3}  & \(\mathbf{t_{\text{O},S}}\) & \(\mathbf{t_{\text{O},S}}\) \\ \hline V/f & 224.00 & 216.00 \\ VFC without encoder & 198.00 & 236.00 \\ VFC n-control & 116.00 & 268.00 \\ CFC & 144.00 & 400.00 \\ CFC with torque control & 135.00 & 252.00 \\ \hline \hline \end{tabular} \(\mathbf{t_{\text{O},T}}\), \(\mathbf{t_{\text{A},T}}\)—duration of the transient state (respectively output current and active current).  
\end{table} 
Table 6: Time characteristics of the output current (I\({}_{\text{O}}\)) and the active current (I\({}_{\text{A}}\)) in the transient state (without an external load). \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}{\(\mathbf{I_{\text{O}}}\)} & \multicolumn{2}{c}{\(\mathbf{I_{\text{A}}}\)} \\ \cline{2-5}  & [**A**] & [\%] * & [**A**] & [\%] * \\ \hline V/f & 0.86 & 47.70 & 0.53 & 29.40 \\ VFC without encoder & 1.77 & 98.30 & 0.49 & 27.20 \\ VFC n-control & 1.99 & 110.50 & 0.29 & 16.10 \\ CFC & 1.05 & 58.30 & 0.45 & 25.00 \\ CFC with torque control & 1.05 & 58.30 & 0.47 & 26.10 \\ \hline \hline \end{tabular}  
* Value related to the full range of the motor rated current (I\({}_{\text{N}}\)).  
\end{table} 
Table 4: Peak values of the output current (I\({}_{\text{O}}\)) and the active current (I\({}_{\text{A}}\)) of the frequency converter in a transient state (without an external load). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Control Mode**} & \multicolumn{4}{c}{**Current Intensity [A]**} \\ \cline{2-7}  & \multicolumn{2}{c}{\(\mathbf{I_{\text{O}}}\)} & \multicolumn{2}{c}{\(\mathbf{I_{\text{A}}}\)} \\ \cline{2-7}  & \(\mathbf{I_{\text{O},MIN}}\) & \(\mathbf{I_{\text{O},MAX}}\) & \(\mathbf{I_{\text{O},AVE}}\) & \(\mathbf{I_{\text{A},MIN}}\) & \(\mathbf{I_{\text{A},MAX}}\) & \(\mathbf{I_{\text{A,AVE}}}\) \\ \hline V/f & 0.58 & 0.51 & 0.55 & 0.16 & 0.12 & 0.14 \\ VFC without encoder & 0.61 & 0.52 & 0.56 & 0.08 & 0.01 & 0.04 \\ VFC n-control & 1.44 & 0.53 & 0.57 & 0.05 & 0.03 & 0.04 \\ CFC & 0.77 & 0.60 & 0.63 & 0.10 & 0.01 & 0.06 \\ CFC with torque control & 0.68 & 0.59 & 0.63 & 0.10 & 0.02 & 0.06 \\ \hline \hline \end{tabular}  
\(\mathbf{I_{\text{O},A}}\),MIN—minimum value, I\({}_{\text{O,A}}\),MAX—maximum value, I\({}_{\text{O,A}}\),AVE—average value.  
\end{table} 
Table 5: Characteristics of the output current (I\({}_{\text{O}}\)) and the active current (I\({}_{\text{A}}\)) in a steady state (without an external load).