The paper solves the problem of increasing the accuracy of measuring torque and use of an electronic torque meter as a feedback sensor of synchronous and induction machines of an electric traction drive. Relevance of the problem and methods for its solving by indirect means using simulation models of electric machines are considered. The theoretical development of the meter is based on the energy model of electric machines in the form of differential equations for active and reactive power balance. This eliminates the direct influence of instability and nonlinearity of inductive elements and takes into account electrical, magnetic, mechanical, and harmonic losses using the simplest algorithms. Key variables of the model in the form of total active power and angular velocity are measured directly, and the high nominal efficiency of traction machines (95%) provides a wide tolerance range for calculating total losses. The information support of the meter is based on the traditional equipment of the traction electric drive, supplemented by voltage sensors of the three-phase inverter circuit. Accuracy characteristics of the meter are predicted under the assumption that the reduced torque measurement error does not exceed (2.5…3.0)% with an error of current, voltage, and speed measuring transducers of 1.5%. A tolerance range of (35…40)% determined for total losses satisfies the accepted conditions. Problems of adapting the meter to the technical characteristics and operating modes of traction machines are considered. Direct torque control algorithms have less accuracy.
The concept of using an electronic meter in a closed control system of a traction electric drive with torque feedback is considered. The purpose of this proposal is to improve the accuracy of torque control to the level of an electronic meter.