Russian Electrical Engineering

A functional diagram is presented, and the operation principle of a system for traction electric drive control with asynchronous motors providing motor torque setting based on the current restrictions of the locomotive energy facility is briefly described. Formulas are derived for setting the stator current and rotor-flux linkage providing a reduction in power loss in an asynchronous motor depending on the operating mode thereof. To verify the adequacy of the obtained formulas, a vector-control system for an asynchronous motor with the orientation of the coordinate axes according to the flux linkage of the rotor has been used. A two-level stand-alone voltage inverter with space-vector modulation has been used in the power channel of the electric drive. Simulation results are presented for an electric drive with a 637-kW motor. It is shown that the greatest reduction in power loss occurs at a rotation frequency close to the rated value, regardless of the value of the resistance torque.

This article deals with an algorithm for generating a set of acceptable values of energy supply indicators. This algorithm has been designed for use in intelligent systems to make decisions on the carrying of heavy trains on limiting sections. Using the generated sets of permissible parameters of operational indicators for weight, speed, and location of oncoming and passing trains will allow sending trains according to energy-efficient train paths. The algorithm contains sections of energy supply and cargo turnover, assessment of the acceptable parameters of electricity supply, and obtaining a set of acceptable parameters of operational parameters of train accommodation.

An electric drive based on a double-inverter-fed induction machine is presented. The control system of the electric drive minimizes the electromagnetic losses both at constant flux linkage in the gap and during its regulation at the optimal level. The considered variant of control permits one to significantly increase the acceptable electromagnetic torque during two-region rate regulation and to improve the energy characteristics.

The effect of ageing on the performance of insulation systems is studied. A program has been developed that determines the residual life of polymeric insulation taking into account all of the factors affecting the insulation’s state. Experimental data on the effect of the chemically active components of the substance adsorbed in the insulation microflaws and the effect of the epoxy oligomer on polyarylates during production are presented. A way to remove the structural and production flaws facilitating the active ageing process is considered.

Modern railway automation and remote control systems are equipped with advanced self-diagnostics facilities. This article is devoted to the development of continuous technical state control of turned-off signal lamps. Application of pulse control using special pulses is proposed. The advantage of such a control circuit is its low sensitivity to the shunting effect of the signal transformer magnetizing inductance. The correct selection of the pulse parameters allows one considerable decreasing the shunting influence of the cable line capacity. It is shown that the pulse test circuit can be implemented by means of the up-to-date contactless semiconductor component base. The pulse control principles of the turned off signal lamps are discussed. An engineering solution enabling one to generate test pulses 5 ms in duration with a time interval of 200 ms is given. The signal processing principles on the control circuit output are considered. The aforementioned solution is integrated to the structure of the signal lamp control power module.

Một phương pháp phát triển mô hình nhiệt của một mô-đun IGBT dựa trên phương pháp tương đồng điện nhiệt được xem xét. Khác với các mô hình nhiệt một chiều truyền thống, mô hình mới này được bổ sung các quan hệ nhiệt giữa các chip. Các tham số của quan hệ nhiệt được xác định bằng cách nghiên cứu mô hình 3D của mô-đun công suất trong môi trường ANSYS. Mô hình được đề xuất nhằm cải thiện chất lượng dự đoán nhiệt độ của các chip mô-đun công suất nhờ cân nhắc đến ảnh hưởng nhiệt tương hỗ giữa các chip.

A model of an electric drive and a grid model of an electric motor are presented. The grid model is used for forward substitution into equations of motion and the calculation procedure intended for calculation motion performance taking into consideration the electromagnetic torque is given. The electromagnetic torque is determined via a static analysis of the grid model of the induction motor operating as a stepper drive or as a drive of a dc brushless motor.

Results of research on the effect of magnetization-curve approximation of the electrotechnical steel and excitation frequency of an asynchronous inverter-fed induction motor (IFIM) on its energy performance with extremal control algorithms based on energy-saving criteria are presented in this article. An IFIM is a variant of a double-fed motor with static frequency converters in the stator and rotor circuits. Its application in a variable-speed drive meets to the greatest extent the main requirements for an ac machine in terms of speed regulation and providing high energy performance. It is shown that application of piecewise linear approximation by three sections and the spline function provides improved values of energy performance relative to the simple approximation by two linear sections due to becoming close to a real magnetization curve. It provides, under otherwise equal values of electromagnetic torque, a higher flux linkage with decrease in magnetization current. Control of the excitation frequency of the asynchronous inverter-fed induction motor has a significant influence on the steel losses of the machine. In the region of low loads, they are particularly important relative to the active losses in the motor windings.

An induction-type linear-pulse electromechanical converter with an external magnetic, electromagnetic, or combined magnetic–electromagnetic shield has been considered. A mathematical model of a converter, which takes into account rapid interconnected electromagnetic, thermal, and mechanical processes, has been developed using the finite-element method. The effect of the geometrical parameters of a shield on the converter performance has been considered. A criterion of efficiency that takes into account the relative values of the efficiency, mass, and stray field of a converter has been introduced. It has been shown that the efficiency of a converter with a combined shield is two to three times higher than that when using a magnetic or electromagnetic shield of the same dimensions.