Unit power factor operation of parallel operated AC to DC PWM converter for high power traction application

This paper deals with the parallel operation of several numbers of PWM converters for a high power traction application. Several considerations are made to reduce the transformer interaction which can cause a current control problem in a severe case. Also, in this paper, a novel control strategy is proposed to achieve a harmonic free primary-side current control under a light load condition using one current sensor independent of the number of converters. In addition, the modified predictive current controller, which is suitable for a digital current controller with a relatively large sampling period, is used. Finally, to verify the system validity, a digital control system with a TMS320C44 microprocessor and a small scale simulator are made and tested.