ZCS concept of single-phase traction supply converters

At the present time the major part of traction systems uses single-phase 25kV/50Hz or 15kV/16,66Hz circuitry to traction vehicles supply. The supply stations of traction systems were made in different ways like rotary converters, cycloconverters and actually DC-link converters. The paper compares the static converter features and introduces the new concept of current-type soft switching DC-link frequency converter. This concept uses the three-phase zero current switch pulse rectifier, current-type, as a modern input unit of current indirect frequency converters including soft switching. The converter has many advantages e.g. the low emissions of harmonic components into the mains, the controlled power factor, the convenient current control in the DC link and low switching losses. This type of converter solves some problems of EMC and can control the converter power factor on the mains side. The suitable delta modulation of the converter is also described in the paper. The measured results were done in the application of the realized pulse rectifier as the input unit of the zero current switching indirect frequency converter with the series resonant DC link.