PWM converters employing GTO"s are proposed to be used for the currently planned Korean High-Speed Train system. In this paper, operating methods and harmonic spectrums are investigated for the PWM modulated voltage controlled GTO AC/DC converter used in the High-Speed Train System. It is shown that harmonic components can be controlled by varying carrier frequency in PWM modulation schemes. Then the input power-factor control scheme is suggested and analyzed. It is found that the power-factor can be varied by controlling the converter input voltage and phase angles between the input supply voltage and the converter input voltage. Finally, simulation programs are developed and converter systems are implemented.