## 2 Materials and Methods
### Development of a Simulation Model of the Traction Drive Without a Control System  
The simulation model of the inverter was developed in the MATLAB18b/Simscape/Specialized Power Systems environment. The power stage of the inverter is implemented using \"IGBT/Diode\" components, while the pulse-width modulation (PWM) algorithm is realized using the \"PWM Generator (2-level)\" block. In the development of the comprehensive model of the traction drive's output section (Figure 6), a simulation model of the asynchronous motor implemented in three-phase coordinates was used, as described in [14]. This model is not presented in detail in the current work, as it has been extensively documented in the referenced study. The validation of this model was carried out in the study [14], where the simulation results under nominal operating conditions--namely, the amplitudes of stator phase currents, rotor speed, and electromagnetic torque--were compared with the manufacturer's data. The deviation in the amplitude of the stator phase currents was 1.7%, in the rotor speed 0.3%, and in the torque 0.74%, indicating a high level of accuracy in the obtained results. It is important to note that the stator and rotor windings of the asynchronous motor in this model were implemented using the MATLAB18b/Simscape/Specialized Power Systems environment, while all other components were developed within the MATLAB18b/Simulink environment. The parameters of the STA-1200 series asynchronous motor required for the development of the simulation model are listed in Table 1. In the comprehensive traction drive model, the simulation model of the asynchronous motor's output section is incorporated within the \"Asynchronous Motor\" block, while the simulation model of the standalone voltage inverter is embedded in the \"Inverter\" block. Since the comprehensive model of the traction drive output section utilizes elements from the MATLAB18b/Simscape/Specialized Power Systems library and operates in continuous-time mode, the simulation was implemented using a continuous solver. The \"Voltage Harmonic Compensation Control Block\" (Figure 6) emulates the functionality of the harmonic voltage compensation control scheme (Figure 2). The operational principle of this control scheme involves comparing a reference signal u with the signal u generated by the reactive power compensator's control system. The resulting error signal is then fed into a PWM modulator. The output of the modulator provides gate signals for the transistors of the active filter. As the objective of the active filter is to eliminate higher-order harmonics in the stator voltage system of the asynchronous motor, the reference signals are proposed to be the fundamental components of the three-phase supply voltage system, defined as follows: \(\mathrm{U_{a}=U_{nom}\cdot exp(j0^{\circ})}\), \(\mathrm{U_{b}=U_{nom}\cdot exp(-j120^{\circ})}\), \(\mathrm{U_{c}=U_{nom}\cdot exp(j120^{\circ})}\). These reference voltages represent an ideal sinusoidal supply and serve as the basis for maintaining voltage quality in the stator circuit. Figure 5: High-pass filter structural circuit. In the process of developing the simulation model within the MATLAB18b/Simulink environment, it is technically incorrect to connect multiple voltage sources in parallel. Since the power circuit of the compensator is implemented as an inverter, the configuration shown in Figure 1 is not suitable for direct simulation due to these limitations. Consequently, two alternative implementation approaches for modeling the compensator's power circuit are proposed:  
1. By using a controlled voltage source connected in opposition to the stator phase voltages of the asynchronous motor. 2. By employing a controlled current source. Figure 6: Comprehensive simulation model of the traction drive with field-oriented control and reactive power compensator.