In this paper, we investigate the reduction of shaft induced voltage using both active and passive filters. An RLC circuit for passive filter and a DC-DC buck converter for active filter is used which can remove the high-frequency spikes leading to the reduction in induced shaft voltage. Buck converter has a minimum-phase behavior and therefore is preferred to any other converters. A static excitation system using 6-pulse thyristor rectifier is employed for 5 kW synchronous generators. Active and passive filters are placed between rectifier and excitation winding of the synchronous generator. As simulation and experimental results show, both filters are capable to remove the parasitic capacitance efficaciously and so induced shaft voltage is mitigated significantly. However, in contrast to the passive filter, active filter shows the better performance to reducing the shaft induced voltage. This reduction can increase the life time of generator's bearing.