CALCULATION OF A MECHANICAL CHARACTERISTIC OF ELECTRIC TRACTION MOTOR OF ELECTRIC VEHICLE

Abstract

The traction characteristic of an electric vehicle is the main characteristic of mechanical system that reflects its key performance indicators. Implementation of the traction characteristic is based on controlling angular speed and torque of electric traction motor in an automatic control system. The static mechanical characteristic of an electric traction motor in an automatic control system is the most important characteristic that determines weight, size and operating characteristics of an electric traction motor and serves as the basis for design. The most common variants of constructive implementation of a traction electric drive are analyzed, and a scheme is chosen for further design. Lagrange’s equation for electric mechanical system with one degree of freedom is written in generalized coordinates. In order to determine the generalized forces, elementary operation of all moments influencing on a moving car has been calculated. The resulting equation of motion of the electric vehicle corresponding to the design scheme, as well as the expressions for calculation of characteristic points of static mechanical characteristics of traction motor (i.e. the maximum and minimum time, minimum power) are obtained. In order to determine the nominal values of the angular velocity and the power of electric traction motor, a method based on ensuring the movement of the vehicle in the standard cycle has been developed. The method makes it possible to calculate characteristic points of the mechanical characteristic with the lowest possible power rating. The algorithm for calculation of mechanical characteristics of the motor is presented. The method was applied to calculate static mechanical characteristic of an electric traction motor for a small urban electric truck.