Energy losses in steady-state operating modes of electric drives, energy characteristics and their improvement

Abstract

The article presents an analysis of energy losses in steady-state operating modes of electric drives and an increase in energy performance. It is shown that the task of correctly determining/calculating the required electric drive power and selecting motors with sufficient power and overload capacity is of extremely important practical importance. The performance, reliability and efficiency of driven machines significantly depend on the correct choice of engines during design. The authors indicated that the passage of energy flow from the network to the working body of the mechanism is accompanied by energy losses in all elements of the electric drive. The need to calculate energy losses during design and operation is due to the fact that the determination of unproductive energy costs is the most important characteristic of the efficiency of the mechanism, and their analysis is the basis for finding ways to save energy. It is indicated that losses in electric machines are divided into constant and variable. Variable motor losses are caused by the flow of currents through the resistances of the power circuit, and therefore are directly related to the motor load. Losses in three types of engines are analyzed. It is shown that to check the engine for heating, it is necessary to take into account only the heating losses that are generated directly in the engine. Relationships are given that allow you to calculate energy losses in the engine to check its operating conditions. An example of a calculation is considered and a number of recommendations are given to further simplify the determination of losses for specific conditions. The article notes that the efficiency of the electromechanical system determines the efficiency of the electric drive, as well as the power factor, which takes into account the efficiency of active energy use. The main measures to increase the power factor of asynchronous motors are considered. The performance of asynchronous electric drives with rheostatic speed control can be achieved by choosing optimal sliding during starting and braking. Since the mechanical characteristics of an asynchronous motor are nonlinear, there is an optimal value of the critical torque that provides a minimum of acceleration and deceleration time for the drive.