Minimization of Electric Heating of the Traction Induction Machine Rotor

The article solves the problem of reducing electric power losses of the traction induction machine rotor to prevent its overheating in nominal and high-load modes. Electric losses of the rotor power are optimized by the stabilization of the main magnetic flow of the electric machine at a nominal level with the amplitude-frequency control in a wide range of speeds and increased loads. The quasi-independent excitation of the induction machine allows us to increase the rigidity of mechanical characteristics, decrease the rotor slip at nominal loads and overloads and significantly decrease electrical losses in the rotor as compared to other control methods. The article considers the technology of converting the power of individual phases into a single energy flow using a three-phase electric machine equivalent circuit and obtaining an energy model in the form of equations of instantaneous active and reactive power balance. The quasi-independent excitation of the induction machine is performed according to the model by stabilizing the current of the magnetizing branch using the algorithms to control the voltage amplitude, synchronous frequency and electromagnetic moment. The magnetizing branch contains resistances of magnetic power losses, which allows us to increase control accuracy. The article considers issues of adapting the energy model to the traction electric drive modes by the criterion of the main magnetic flow constancy. The information support task is solved by a measuring observer, which allows us to calculate the parameters of the generalized energy flow using the measurements of the primary current and voltage sensors and to implement the aforesaid model and control algorithms in software. The article presents the results of modeling traction and energy characteristics of the induction machine and shows the effect of reducing electric losses in the rotor in the main magnetic flow constancy modes.