This paper proposes a new step-up DC-DC converter topology with a high voltage conversion ratio for renewable system applications. The desired high voltage gain and satisfactory performance can be achieved by employing only a single power switch with simple control technique. The proposed converter can be used to step up the low voltage generated from renewable energy sources, such as solar photovoltaic modules, to the high level of the dc bus voltage, obtaining low-to-high voltage conversion ratios of approximately 30 times without adopting extremely large duty cycle. Employing the proposed converter the low input voltage (20-50Vdc) can be boosted up to the high output voltage level about 600Vdc at the dc-link bus required for the three-phase inverter feeding the three-phase motor drive system. In this paper, the proposed converter configuration with only one active power switch is presented. The operating principleincluding analysis of the steady-state performance characteristics under continuous conduction mode (CCM) operating conditions is described. In addition, the control strategy is developed in order to obtain the satisfactory output voltage regulation. Finally, simulation results are shown to demonstrate the effectiveness of the proposed converter with its control strategy to achievehigh step-up conversion ratios under different operating conditions.