VCMIPWM Scheme to Reduce the Neutral-Point Voltage Variations in Three-Level NPC Inverter

ABSTRACT

This paper presents variable common mode injection pulse width modulation (VCMIPWM) technique to reduce the neutral-point voltage variations in three-level neutral-point-clamped (NPC) inverter. The neutral-point voltage varies with the modulation index and the variation is high in the low modulation index region. Therefore, proper common mode voltages are calculated for various modulation index regions and are carefully injected with the reference phase voltages. The calculation is based on equalizing the switching times of the zero/redundant vectors in a switching cycle for various modulation index regions. The simulation results show the improvement in the neutral-point voltage balancing of the inverter in the VCMIPWM scheme compared with the sinusoidal pulse width modulation (PWM). The proposed PWM is implemented in field programmable gate array (FPGA) and the experimental results are shown to verify the practicability of the proposed method.

Keywords:

• Common mode injection PWM
• Common mode voltages
• FPGA
• Neutral-point clamped inverter
• Neutral-point potential
• Zero/redundant

Additional information

Notes on contributors

S. Nageswari

S.Nageswari received the BE degree in Electrical and Electronics Engineering from Government College of Engineering, Tirunelveli, India, in 1997, and the ME degree in Power Electronics and Drives from Government College of Technology, Coimbatore, India, in 2005. She then obtained her PhD degree in Power Electronics and Drives from Anna University, Chennai, India, in 2014. She has 14 years of experience in teaching. She is currently working as an assistant professor in the Department of Electrical and Electronics Engineering in AC College of Engineering and Technology, Karaikudi, India. She has published many papers in national and international journals and conferences. Her fields of interest include power quality, power electronics, PWM techniques for power converters, and multilevel inverters.

E-mail: [email protected]

V. Suresh Kumar

V. Suresh Kumar graduated in Electrical & Electronics Engineering from Thiagarajar College of Engineering, Madurai, India, in 1994, and postgraduated in Power Systems from National Institute of Technology, Tiruchi, India, in 1995. He then obtained his PhD degree in Power Quality & Harmonics from Madurai Kamaraj University in 2006. From 1997, he has been faculty of Electrical and Electronics Engineering at Thiagarajar College of Engineering, India, and currently working as an associate professor. He received Carrier Award for Young Scientist (2006) from Ministry of HRD, India, and Young Scientist Fellowship award (2007) from Tamil Nadu State Council for Science & Technology, India. As a member of energy audit cell, he conducts power quality studies at various industries. He has published 40 papers in national and international journals and conferences. His fields of interest include power quality, distributed generation, and power electronics.

E-mail: [email protected]