Southwest Jiaotong University
The main new developments compared to the KTX-I are in the traction equipment and the carbody. The motors are newly developed three-phase asynchronous induction motors, rather than synchronous motors as in the KTX-I. The motors are supplied by traction converters with integrated gate-commutated thyristor (IGCT) rather than silicon-controlled rectifier (SCR) components as in the KTX-I. IGCT was the most advanced version of the Gate turn-off thyristor (GTO) used for control of high-power applications at the time, and the use of ABB-supplied IGCTs as the switching element in the rectifier and inverter modules of HSR-350x converters was a world's first in rail vehicles. However, testing found limited improvements in efficiency and noise levels, and problems with reliability. Each traction converter consists of two parallel-switched four-quadrant converters, which function as rectifier modules by converting single-phase alternating current (AC) from one main transformer winding each to direct current (DC), a 2,800 V DC intermediate circuit, one inverter module converting the DC supply to the three-phase AC supply for traction motors, an auxiliary inverter for the supply of motor and converter cooling fans, and resistors for rheostatic braking that are also connected to the DC circuit. The variable voltage variable frequency (VVVF) inverters are voltage-sourced with pulse-width modulation (PWM) control, rather than current-sourced with phase fired control (PFC) as in the KTX-I. Each converter supplies the motors on two axles of a bogie, providing for individual bogie control. New main transformers with a 15% weight reduction and a 20% power increase were also developed. The single-arm pantograph is a new development for the planned higher speed. The redesigned bogies and suspensions were tested on the roller rig of Southwest Jiaotong University in China at simulated speeds of up to .