Andrienko D. Asynchronous electric drive of mismatched rotation with pulsecurrent limitation in the circuit of electrically coupled rotor rectifiers

Dissertation for the degree of candidate of technical sciences in the specialty 05.09.03 – electrical complexes and systems. National University «Dnipro Polytechnic», Dnipro, 2021. 20 In the dissertation work, a scientific and practical problem was solved related to the study and creation of a new type of electric drive of coordinated rotation based on asynchronous motors with pulse-current limitation with electrically connected rectifiers in phase rotors, which have self-synchronization properties under uncertain types of mechanical effects with high energy and relatively small weight, dimension and cost indicators in comparison with known systems of electric drives of mismatched rotation. A dimensionless generalized parameter (coefficient) of synchronization is obtained, which depends on the design features of the circuit solution, the parameters of the rotor circuit of the asynchronous motor with wound rotor (AMWR) and the ratio of the static moments of an asynchronous electric drive of matched rotation and analytical expressions for determining the equalizing torque and current between the rotors of the motors. The parameters of the electrical circuit of the inverter of a network-controlled converter of mismatched rotation with electrically connected rectifiers in the rotor circuit have been determined, at which reliable operation of the inverter and its protection from emergency currents are ensured. A simulation computer model has been developed that takes into account the interrelated electromagnetic and electromechanical processes in the electric drive system of mismatched rotation with pulse-current limitation in the circuit of electrically connected rotor rectifiers, and allows to establish effective methods and methods for controlling the converter to obtain the best synchronizing properties of the AMPR while maintaining a high level of efficiency and drive power factor. Analytical ratios of the electromechanical process in an electric drive of mismatched rotation were obtained due to which it was found that the inconsistency in the steady state is inversely proportional to the product of the synchronization coefficient and the nominal slip of the motor, and the electromechanical time constant is proportional to this product. A method is proposed for determining the speed mismatch of AMPR in the system of an electric drive of mismatched rotation, which takes into account the presence of both static and dynamic disturbing high-frequency moments acting on the AMPR. This allows, with sufficient accuracy up to 6.6% in constant, and up to 25.7% in transient modes of their operation, to assess the inconsistency of the AMPR speeds depending on the passport data and parameters of the AMPR equivalent circuit. The conducted experimental studies confirm the operability and efficiency of the proposed technical solution for an asynchronous electric drive with a pulse-current limitation in the circuit of electrically connected rotor rectifiers.