International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 11 Issue: 06 | Jun 2024
p-ISSN: 2395-0072
www.irjet.net
COMPARISON OF MODULATION STRATEGIES FOR MULTI LEVEL INVERTER-FED INDUCTION MOTOR DRIVE Nenavath Sunitha1 and Dr. S Tara Kalyani 2 1 M.Tech, Student, Dept. of Electrical and Electronics Engineering, JNTUHUCEST, Hyderabad, India. 2 Professor of Electrical and Electronics Engineering JNTUHUCEST, Hyderabad, India.
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use of MLIs can address these concerns, making the system more efficient and reliable. The primary goal of this study is to enhance the performance of induction motor drives by comparing various modulation schemes for multilevel inverters. Understanding the benefits and drawbacks of each strategy allows us to discover the best way for certain applications. By addressing restrictions in solid-state switching device ratings, multilevel PWM inverters enable higher-power adjustable-frequency drives to regulate bigger motors.
Abstract - Most multilevel inverter-fed motor drive systems
largely use pulse width modulation (PWM) techniques, which give a steady switching frequency, favorable total harmonic distortion (THD) characteristics, and lower ripple current. Harmonic loss is evaluated using several PWM strategies, including In-phase sinusoidal pulse width modulation (IPSPWM), phase opposite sinusoidal pulse width modulation (POSPWM) and space vector pulse width modulation (SVPWM). These techniques are then applied to an induction motor drive for comparison. The suggested methods employ a multilevel inverter to achieve better speed control for induction motor drives. The study compares several modulation strategies in terms of harmonic content, speed, and torque characteristics of the drive system. The major goal is to investigate the effects of various modulation approaches on the performance of a multilevel inverter-fed drive system and which is the best among them. The proposed techniques are implemented in the MATLAB/SIMULINK environment.
1.1 Principle of operation of NPC Inverter There are several uses for three-phase, three-level NPC converters with PWM control in ac machine drives and dc-toac power supplies. The performance criteria will be provided to evaluate and compare various PWM techniques [1]. Providing a point-by-point grasp of the neutral point clamped inverter, the three-level NPC inverter is designed and implemented with 12 IGBT switches which includes three phases: Each phase consists of four switching devices (usually IGBTs or MOSFETs), four diodes, and two capacitors. Switching Devices: Each phase leg contains four switches (S1, S2, S3, S4) and four diodes (D1, D2, D3, D4). DC Bus Capacitors: Two capacitors divide the DC bus voltage into two equal portions, forming a neutral point.
Key Words: PWM, Induction motor drive, Neutral Point Clamped (NPC) inverter, In-phase sinusoidal PWM, phase opposite sinusoidal PWM and space vector PWM.
1. INTRODUCTION Multilevel inverters (MLIs) have gained a lot of interest in recent years for their use in high-power and high-voltage applications because of their ability to generate higher voltage levels with less harmonic distortion and electromagnetic interference. They are becoming increasingly used in industrial applications, renewable energy systems, and electric drives. When used to drive induction motors, MLIs offer various advantages over standard inverters, including enhanced output voltage quality, increased efficiency, and lower motor stress. Induction motors are frequently utilized in industrial applications because of their reliability, robustness, and low control needs. However, when powered by typical two-level inverters, these motors frequently exhibit substantial total harmonic distortion (THD) and significant power losses. The
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Using clamping diodes, the center of each pair is clamped to the center-tapped capacitor's [2]. Controlling the switching devices produces three voltage levels: positive half DC bus voltage (+Vdc/2), zero (0), and negative half DC bus voltage (-Vdc/2). When the upper two switches (S1 and S2) are turned on and the lower two switches (S3 and S4) are turned off, the output voltage is +Vdc/2. When the middle switches (S2 and S3) are activated while the outer switches (S1 and S4) are turned off, the output voltage is 0, the current passes from the neutral point (NP) and when the lower two switches (S3 and S4) are turned on and the upper two switches (S1 and S2) are turned off, the output voltage is -Vdc/2. Fig. 1 shows the three phase NPC inverter and induction motor drive as load.
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