Application of matrix converter in auxiliary drive system for diesel locomotives

Auxiliary drive system is one of the most important parts in diesel locomotives. In order to enhance system efficiency, an auxiliary drive system using 3-phase to 3-phase matrix converter and 3-phase to 1-phase matrix converter is proposed for diesel locomotive. A 10 kW 3-phase to 3-phase matrix converter prototype is implemented to feed AC motors in the drive system. According to different working condition requirements of AC motors, three control methods (constant voltage constant frequency control, variable voltage variable frequency control and slip frequency closed loop control) have been employed in the control system of 3-phase to 3-phase matrix converter. A 3-phase to 1-phase matrix converter using reverse blocking IGBT is applied to provide single phase AC facilities with power supply. A simplified average voltage pulse width modulation strategy is proposed to modulate the 3-phase to 1-phase matrix converter, and a novel commutation method is proposed to shorten commutation time and reduce power losses of bi-directional switches. Compared with conventional mechanical drive, fluid drive and DC drive, the power density, efficiency and reliability of the auxiliary drive system are enhanced by use of matrix converter. Experimental tests have been carried out which demonstrate the advantages and feasibility of the proposed auxiliary drive system.