Cascaded Multilevel Inverter Based Transformerless Traction Drive

Electric railways have been introduced as a solution to the environmental problem caused by the diesel engines. Generally, in an electrified railway system, a transformer is used to step down the AC supply which can be used by the traction motors. This magnetically coupled transformer lead to high weight, several losses and reduced efficiency. This book presents the application of the cascaded multilevel inverter in the railway traction drive, thus leading to a transformer less traction drive. An IGBT based-cascaded multilevel inverter can be used to lower the supply voltage to a level convenient for the induction motors. This eliminates the need of a transformer in the railway traction drives and also results in the reduction in the Total Harmonic Distortion of the voltage to be supplied to the traction motors.