Three phase to Co-phase railway electrification approach using voltage synthesizing electronic phase shifter (EPS)

In this paper, an electronically based three phase to Co-phase conversion approach for traction power supply application is presented. The low frequency transformer used to generate co-phase system is replaced with an electronic phase shifter (EPS) thus less space is needed and consequently higher power density. Moreover, the proposed system controllability of the EPS output voltage gives the advatage to increase the power quality of the locomotive-utility interface. The controllability achieved by harmonic injection PWM AC chopper to control the phase and amplitude of the output voltage. Harmonic trap is required to eliminate the harmonic generated by the modulation technique. Analyses of the system and simulation results are provided. Experimental verification of the electronic phase shifter concept is included.