Improving the energy characteristics of a four-quadrant converter with pulse-width modulation

Abstract

The characteristics of the input energy converter of an electric locomotive with an induction traction electric drive were studied. The efficiency of the 4QS converter has been increased and the level of current harmonic distortions in the power supply system has been reduced. The research resulted in proposals for improving the control algorithm of the input energy converter to improve the traction-energy indicators of the electric drive and reduce the emission of high-frequency harmonics into the contact network. The results were obtained on the basis of simulation modeling of the "traction transformer – 4QS-converter" system on the example of the alternating current electric locomotive DS3 (Dnipro-Simens-3). Modeling of the operation of the 4QS-converter of the electric locomotive was performed for the case of the maximum load of the drive under a traction mode. Two versions of the input converter control algorithm were studied and compared: the basic version of the DS3 electric locomotive and the modified version proposed by us. It was found that in the case of the basic variant of the converter control algorithm, conditions are created at certain time intervals when the capacitor of the constant voltage link on the secondary winding of the traction transformer is discharged under a traction mode. The consequence of this is a decrease in the efficiency factor of the converter and a deterioration of the harmonic distortion factor of the rectified voltage. In the modified algorithm, the discharge time of the capacitor of the constant voltage link on the secondary winding of the traction transformer is significantly reduced and the efficiency of the 4QS converter is increased