## 1 Introduction
### Selecting Direct Torque Control Imitation Model
Figure 7: Dependencies of currents (**a**) and flux linkages (**b**) of the stator on the degree of deviation of the phase A voltage amplitude of the stator in case of damage to 5 turns of the phase A winding of the stator in steady-state mode. is the angular velocity of the magnetic field. Since the investigations were carried out at a constant angular velocity of the field, the change in the coherence will be directly proportional to the change in the supply phase voltage. The flux linkages of all phases showed an upward trend at higher than the nominal value of the phase A voltage amplitude. At the same time, the flux linkage value of the damaged phase was lower than the flux linkage values of other phases. It should be noted that the phase flux linkages of the intact stator phases were the same, i.e., \(\psi_{\text{sb}}=\psi_{\text{sc}}\). Investigation of the Effect of Simultaneous Asymmetry of the Feed Voltage System and Motor Windings in the Different Phases  
In the investigation of the effect of asymmetry of the feed voltage system on the starting characteristics of the asynchronous motor under conditions of asymmetry of the stator windings, the following adjustments were made in the simulation model. Adjustments of active resistance and inductance of leakage of the damaged phase equal to five turns of the phase A winding of the stator were introduced into the \"Unit for determining motor phase currents\". The number of turns of the damaged turns was reduced by five turns in the \"Block for calculating mutual inductances and total inductance of the magnetization circuit\". Respective variations of the amplitude were entered into the sinusoidal voltage source of phase B U\({}_{\text{sc}}\). As a result of the variations for phase B voltage amplitude equal to the nominal value, \(+2\%\), \(+1\%\), \(-1\%\), and \(-2\%\) deviations from the nominal value, the starting characteristics of phase current system and phase flux linkages of the motor in the steady-state mode were taken. The data are included in Table 5. Based on the experiment results, the following dependency was observed in the phase currents and phase flux linkages. In the steady-state mode, constant ratios of the amplitudes of stator current and amplitudes of the stator flux linkages of the phase with the deviation of the voltage amplitude from the nominal value and phases with the nominal value of the voltage amplitudes were detected. Hence, the diagrams of the instantaneous values of currents and flux linkages are not presented here. The results in Table 5 were used to build the dependencies of currents (Figure 8a) and flux linkages of the stator (Figure 8b) on the degree of deviation of the phase B voltage amplitude of the stator in case of the asymmetry of stator windings in the steady-state mode. As suggested in Figure 8a, the dependencies of the stator currents of all phases on the degree of deviation of the phase B voltage amplitude are non-linear. It should also be noted that when the voltage amplitude of phase B was equal to the nominal value, the currents  
Figure 8: Dependencies of currents (**a**) and flux linkages (**b**) of the stator on the degree of deviation of the phase B voltage amplitude of the stator in case of damage to 5 turns of the phase A winding of the stator in the steady-state mode. of all phases had a local maximum. With the phase B voltage amplitude increasing, the current of this phase was also increasing while the currents of other phases were decreasing. With the phase A voltage amplitude decreasing, the current of this phase decreased, with the currents of other phases initially decreasing down to the local minimum and increasing afterwards. It should be noted that the current of the damaged phase A was higher than the current of the intact phase C in all sections of the diagram. The variation in the flux linkages of all phases caused by the deviation of the voltage in one of the phases (Figure 8b) was linear.