Voltage utilization ratio increasing and Neutral Point Potential Balancing of NPC inverter based on zero sequence voltage for linear induction motor drive

This paper presents the ways to improve the performance of linear induction motors based on the three-level neutral point clamped inverter. In SPWM control method, the low DC-link output voltage utilization ratio causes the inefficiency of power. Moreover, the unbalance of neutral point potential would cause the output voltage out of control. Due to these problems, a zero sequence voltage inserting strategy is introduced, to enhance the output voltage utilization ratio, which also reveals the relationship between SPWM and SVPWM, and to balance the neutral point potential. In addition, the simulation and experiment results prove the strategy in order to solve the voltage utilization ratio problem and the neutral point potential problem. At last, the experiment results for LIM drive are given, which show the good performance characteristics of LIM that demonstrate the strategy mentioned before.