Vector control system of electric traction drive with power losses minimization

Abstract

Based on the operating conditions analysis of electric traction drives of locomotives, it has been established that the vector control systems for an asynchronous motor fully satisfy all the requirements. On the basis of a T-shaped equivalent circuit, a mathematical model of an induction motor is presented, taking into account losses in the stator steel, the effect of the rotor current and saturation displacement. An algorithm for the formation of the optimal, from the point of view of power losses, task for the rotor flux linkage when using a vector control system with the orientation of the axes of the coordinate system along the rotor magnetic field, is developed. The limiting factors are the limitations on the current and voltage of the motor stator, the diesel generator set power. A shared control system for an electric traction drive with asynchronous motors has been developed, which provides direct control of wheel slip with a subordinate vector control system that minimizes power losses. The results of modeling in a steady-state operation and a start-up mode for an electric traction drive of a two-axle bogie with axial support and 630 kW asynchronous motors with the use of various options for organizing circuit reentrances are presented.

Modeling of energy-efficient direct torque control system for traction induction motor

“…Analysis of expression (2) shows that the optimal rotor flux ratio is usually below the nominal value for low resistance torques and greater than the nominal value for low speeds and high resistance torques. The range of variation of the rotor flux ratio is limited to 30...100% of the nominal value to ensure the highly dynamic operation and no saturation of the magnetic system.…”

“…The efficiency of electric drives is determined primarily by the efficiency of motors, the power loss of which depends not only on the resistance torque, which directly affects the values of stator and rotor currents but also on the parameters of the motor substitution scheme, rotor speed, power source parameters, motor power, modes of operation, operating conditions, etc. Nowadays traction electric drive has, as a rule, three variants of asynchronous motor control systems-scalar control system, a vector control system, and a direct torque control system [1,2,3,4].…”