High voltage three PWM rectifiers-seven-level NPC voltage source inverter cascade. Application to the induction machine drive

In the paper, we study a new high voltage cascade constituted by three PWM rectifiers and a seven-level NPC voltage source inverter. This cascade is applied to the induction machine drive. In the first case, we analyse the performances of this cascade in the open loop of the DC output voltage of each PWM rectifier, and we compare these, with the cascade: one PWM rectifier-seven-level NPC VSI. In the second case, we propose to enslave the output DC voltage of the PWM rectifier using classical regulator (PI). Therefore, we analyse the performances of this cascade in the closed loop of the output DC voltage of each PWM rectifier. The result obtained are full of promise to use this cascade in high power fields such as electrical traction.