## 2 Materials and Methods
### Conditions of Measurements  
In terms of the available methods of controlling drive parameters, several basic variants can be distinguished including [6; 11]:  
* Scalar control: \(\bigcirc\) V/f (Volts/Hertz) = const.;
* Indirect Field-Oriented Control (IFOC): \(\bigcirc\) Voltage Mode Flux Control (VFC);
* Direct Field-Oriented Control (FOC): \(\bigcirc\) Current Mode Flux Control (CFC);
* Direct Torque Control (DTC): \(\bigcirc\) SERVO.  
The extended characteristics of the modes are presented in Table 1.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Method** & **General Characteristics** \\ \hline \multirow{8}{*}{V/f} & Scalar control—the stator flux is constant due to the proportionality of voltage and frequency \\  & Default setting for asynchronous motors without encoder feedback \\  & Suitable for general applications (conveyor belts, trolleys, hoists with counterweight), with low \\ \cline{1-1}  & dynamic response requirements \\ \cline{1-1}  & The simplicity makes it widely used in industry \\ \cline{1-1}  & A flux-oriented motor model is not used for V/f characteristic \\ \cline{1-1}  & Possible control of a group of electric motors \\ \hline \multirow{8}{*}{VFC} & Belongs to the group of IFOC methods \\ \cline{1-1}  & A flux-oriented motor model is used for VFC characteristic \\ \cline{1-1}  & Suitable for general applications (conveyor belts, trolleys, hoists with counterweight) \\ \cline{1-1}  & Possible control of a group of electric motors \\ \cline{1-1}  & Dynamic response may be improved in comparison to the scalar method \\ \cline{1-1}  & Voltage and current harmonics may be reduced in comparison to DTC methods \\ \hline \multirow{4}{*}{VFC and hoist/VFC n-control and hoist} & The hoist function automatically provides all functions necessary for operating an unbalanced hoist \\ \cline{1-1}  & Monitoring functions are activated (preventing the drive from starting): monitoring the output \\ \cline{1-1}  & current during the pre-magnetization phase, avoiding sag when the brake is released through load \\ \cline{1-1}  & Braking using a direct current injection (without braking resistor on the converter) \\ \cline{1-1}  & A constant current with a rotating field frequency of 5 Hz is supplied during the braking process \\ \cline{1-1}  & A greater braking torque acts at a slower speed but it drops as the speed increases \\ \cline{1-1}  & The braking time and consequently the duration of the braking current depends on the load \\ \cline{1-1}  & connected to the motor \\ \hline \multirow{2}{*}{VFC and flying start} & Synchronization of the converter to a motor that is already running \\ \cline{1-1}  & Used in drives that are not braked actively, run on for a long time or are turned by a flowing \\ \cline{1-1}  & medium, (e.g., pumps and fans) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of motor control modes [2; 6; 9; 11].  
The analysis of the characteristics (Table 1) shows significant differences in the control modes and the quality of the drive operating parameters (in particular, the rotational speed overshoot in the start-up phase, the accuracy of keeping the speed in a steady state, and the start-up time). Due to the described differences in each of the motor test runs, the following control modes were checked: scalar (V/f), vector (VFC without encoder, VFC n-control with encoder, CFC, and CFC with torque control) [2; 6; 9; 11].