**A MULTILEVEL INVERTER TOPOLOGY FOR A FOUR-POLE INDUCTION-MOTOR DRIVE USING DC-LINK
**

Author’s Name : D Lakshmi Devi

Volume 05 Issue 04 Year 2018 ISSN No: 2349-2503 Page no: 9 – 12

**Abstract:**

A multilevel inverter topology for a four-pole induction-motor drive is presented in this paper, which is constructed using the induction-motor stator winding arrangement. A single dc source with a less magnitude when compared with conventional five-level inverter topologies is used in this topology. Therefore, power balancing issues (which are major challenges in conventional multilevel inverters) are minimized. As this configuration uses a single dc source, it provides a path for zero-sequence currents because of the zero- sequence voltages present in the output, which will flow through the motor phase winding and power electronic switches. To minimize these zero-sequence currents, sine–triangle pulse width modulation (SPWM) is used, which will shift the lower order harmonics near to switching frequency in the linear modulation region. However, in the case of over modulation, harmonic voltages will be introduced close to the fundamental frequency. In this regard, a modified SPWM technique is proposed in this paper to operate the drive in the over modulation region up to the modulation index of 2 /*√*3. The proposed quad two-level inverter topology is experimentally verified with a laboratory prototype on a four-pole 5-hp induction motor. Experimental results show the effectiveness of the proposed topology in the complete linear modulation region and the over modulation region.

**Keywords:**

Back-to-Back Converter, Dynamic Performance, Induction Machine Drives, Open-End Winding and Unity Power

Factor

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