The Traction Induction Motor Magnetic Circuit Saturation Influence on the Variable Electric Drive Energy Efficiency

Currently, variable frequency induction motors (IM) are widely used as traction machines. This is primarily due to the semiconductor devices improvement, with the help of which the traction IM are powered and the its operation modes are regulated. During the frequency-controlled IM operation, the problem arises at determining their optimal control parameters when the load on the IM shaft changes. As a rule, traction IMs are characterized by a change in the load over a wide range and, therefore, to increase their energy efficiency, it is necessary to use the optimal regulation for the supply voltage and the current magnetization reversal frequency in the IM windings. With wide supply voltage regulation, the magnetic flux saturation in the IM stator core changes in proportion to it. With an increase in the magnetic flux saturation, the stator winding current the reactive component grows nonlinearly, causing an magnetic losses increase and a decrease in the IM efficiency. The article analyzes the frequency-controlled IM operation modes in order to determine their operation optimal mode when the voltage and supply voltage frequency change, taking into account the nonlinear change in the saturation for the IM magnetic system.