Altyn Besterekova

This paper addresses the problem of improving the efficiency of the traction electric drive of an agricultural electric vehicle operating under variable load conditions typical of agricultural transportation. The study substantiates the feasibility of employing a low-power (2 kW) induction motor as a cost-effective, technically robust, and reliable solution for mobile power systems. Particular attention is given to the operating characteristics of the traction drive under fluctuating loading conditions, which significantly affect the energy efficiency and overall performance of agricultural electric vehicles. A comprehensive structural and mathematical model of the induction motor was developed based on a proprietary implementation without the use of standard MATLAB R2020b/Simulink library blocks. The model was formulated using the transformation of a three-phase coordinate system into a two-phase stationary α–β reference frame, enabling a more accurate representation of the electromagnetic and electromechanical processes occurring within the machine. The analysis was carried out with consideration of transient processes, dynamic characteristics, and energy performance under realistic conditions regarding the influence of control strategies on the energy consumption of the electric drive system. The results of this can be applied to the design and optimization of electric transportation systems for agricultural applications, as well as to the development of energy-efficient control algorithms for traction electric motors.

This study considered the issue of increasing the synchronizing capacity of a system for the coordinated rotation of asynchronous motors. Electromechanical relationships were obtained for changes in the value of the supply voltage of individual motors, the total rotor resistance (Ra), and the angular positions of the rotors (φ₁, φ₂, and φ₃), with possible changes in angular misalignment. Additionally, we created an algorithm for calculating the currents and torques of the system’s motors within 0 and 90° and constructed the relevant mechanical characteristics. Ultimately, we developed various versions of multi-motor asynchronous electric drives with regulation and supply voltages (U_n = 0.7 ÷ 1.0), featuring increasing and equalizing torques (M_n = 1.0 ÷ 1.4) in the system as a whole, along with the preliminary synchronization and synchronous braking of all motors.

In the proposed article, the issues of increasing the synchronizing ability of the system of coordinated rotation of asynchronous motors are considered. Based on the T-shaped equivalent circuit, electromechanical relationships were obtained with changes in the value of the total rotor resistance and the supply voltage of individual motors. An algorithm for calculating the torques, stator and rotor currents of the motors of the system has been compiled. Based on the calculations obtained, the mechanical characteristics of the system asynchronous motors are constructed for various values of total resistance, supply voltages and rotor positions. The obtained data and graphs confirm the adequacy of the theory obtained in an analytical way. Functional and structural diagrams in small scales have been compiled, which allow simulating transient operation modes of multi-motor asynchronous electric drives in the Matlab application package. Multi-motor asynchronous electric drives with adjustable supply voltages, as well as with preliminary synchronization and synchronous braking, have been developed. Compilation of a program for the stability of a nonlinear system of a multi-motor asynchronous electric drive (MAEDs) with a thyristor voltage converter (TVC) in Matlab. Also, the modes of soft start, load shedding and surge on the motor shaft are simulated, confirming the stability of the system.