AC locomotive conversion systems without heavy transformers: is it a practicable solution?

All actual AC locomotives have an onboard line transformer to reduce line voltages to levels suitable to power electronic devices and to guarantee galvanic insulation to the on board equipment. Unfortunately, such a transformer is heavy, expensive and represents one of main reasons why traction vehicles often exceed the targets for weight and dimensions. Two innovative conversion systems have been studied, which permit the use of transformers of greatly reduced size. Suitable control and modulation techniques have been also developed, and some simulation results are presented. In addition, a further analysis has been carried out to allow a fair comparison between one of the two innovative loco electrical drive systems and a conventional one, taking into account their reliability performances. Some important achievements are shown and the complete set of the results is presented and discussed.