In this paper, we analyzed and simulated performance enhancement scheme of electric-vehicle (EV) charging system based on power line communication (PLC). For reliable EV charging system, impulsive noise which is generated by random on-off pattern of various electric devices in EVs should be mitigated efficiently. Impulsive noise can deteriorate the frame synchronization performance and bit error probability. So, in this paper, we propose a simple frame synchronization scheme based on repeated orthogonal Kasami sequence (ROKS). From the simulation results, it is confirmed that the results of the paper can be applied to design of various applications for in-home, in-plane, in-ship, and in-vehicle scenarios.