2018-01-0766 Published 0 3 Apr 2018 © 2018 SAE International. All Rights Reserved.Energy Method for Torque Control of a Synchronous Traction Motor Viktor Smolin and Irina Topolskaya South Ural State University Sergey P. Gladyshev University of Michigan-Dearborn Citation: Smolin, V., Topolskaya, I., and Gladyshev, S.P., “Energy Method for Torque Control of a Synchronous Traction Motor,” SAE Technical Paper 2018-01-0766, 2018, doi:10.4271/2018-01-0766. Abstract The problem of increasing the accuracy of determining the torque and the load angle of the permanent magnet synchronous motor of an electric traction drive to the predicted level (2.5...3)% of the full-scale error is solved by an indirect method. We considered the algorithms for calculating the generalized current and voltage of the electric motor, the total power, the instantaneous values of the power factor, and the sine of the phase angle between the first harmonics of voltages and currents. We determined the requirements for the accuracy of determining these values at the level of 1% of the full-scale error. We considered the algorithms for determining the total instantaneous power losses by the indirect method at the predicted level (15...20)% of the full-scale error with the efficiency of the motor (90...95)%. The obtained results are inte - grated into the energy model of the electric motor as differential equations of the instantaneous active and reactive power balance of the electromagnetic system and the single-mass mechanical load. The equation of active power balance under - lies the algorithms for controlling the torque and the voltage amplitude of the motor. Basing on the reactive power balance equation, we formed the algorithm for monitoring the induc - tances of the electrical machine stator. The obtained algorithms are adapted to the mode of power-efficient control of the motor by the criterion of the zero-equal phase angle between the first harmonics of voltage and current and to the mode of the zero-equal phase angle between the electromotive force and the stator current. We considered the problems of adapting the algorithm for controlling the voltage amplitude to the mode of power limitation of the permanent magnet synchronous motor at the nominal level. The work contains the results of modeling the control modes of the real traction motor. Introduction The electric traction drive, on the analogy with the piston engine, performs the basic function of control - ling the running torque T at the free coordinate ω r (angular speed). Such operating principle ensures a smooth development impulse loads and the connectability of elec - trical machines into a multi-engine unit. High accuracy torque meters [ 1-3] used in test units of the electric traction drive. Indirect methods of determining the torque and load angle are mainly used [ 4] in the AC electric drive with the vector control [ 5], direct torque control [ 6] and instantaneous power control [ 7]. The accuracy of indirect methods is not high and estimated by the value of ±10% of the full-scale error [ 8]. The reason for this is the failure to consider a number of factors in energy transformations of synchronous machines. The most significant are magnetic and mechanical power losses, temperature changes in the parameters and the disturbing effect of the magnetization energy of synchro - nous machines. Consideration of these factors enables to increase the accuracy of determining the torque and the load angle in the steady-state conditions of medium- and high-power electrical machines up to (1 ... 3)% of the full-scale error [ 9, 10]. The paper solves the problem of the development of algorithms to determine the torque and the load angle in the dynamic modes of the synchronous machine at a predict - able level (2.5 ... 3)% of the full-scalle error in order to achieve a high quality of control by the coordinates of the electric traction drive. Problem Statement The method of determining the e