Simulation Analysis of Three, Five, Thirteen, Fifteen, Twenty One and Thirty One Level Cascaded H-Bridge Multilevel Inverter

K. Rajani
2017 International Journal for Research in Applied Science and Engineering Technology  
Multilevel inverters (MLI) becomes more accepted over the last few years in high power application of electrical engineering with the advantage of less disturbances and the possibility to work at lower switching frequencies as compared to conventional two-level inverters. In this paper the simulation of single phase multilevel inverter is present. Simulation of three level, five level, seven level, nine level, eleven level, thirteen level and fifteen level inverters are done in MATLAB. These
more » ... in MATLAB. These different level inverters are realized by neutral point clamped (NPC) or diode clamped topology of multilevel inverter. In this paper pulse width modulation control strategy is used for control the switches at appropriate conducting angles. The comparative results are presented for multilevel inverter up-to fifteen level which shows the total harmonic distortion is reduces as the number of level increases. I. INTRODUCTION Multilevel converters (or inverters) have been used for dc-to-ac power conversion in high power applications such as utility and large motor drive applications. Multilevel inverters provide more than two voltage levels. A desired output voltage waveform can be synthesized from the multiple voltage levels with less distortion, less switching frequency, higher efficiency, and lower voltage devices. There are three major multilevel topologies: cascaded, diode-clamped, and capacitor-clamped [l-11]. For the number of levels (M) or some applications such as reactive and harmonic compensation in power systems, these multilevel converters do not require a separate dc power source to maintain each voltage level. Instead, each voltage level can be supported by a capacitor and proper control [6-7, 1]. However, for M>3 and applications involved in active power transfer, such as motor drives, these multilevel converters all require either isolated dc power sources or a complicated voltage balancing circuit and control to support and maintain each voltage level [7] . In this aspect, the three existing multilevel converters are neither operable nor complete for real (active) power conversion because they all depend on outside circuits for voltage balancing. For the number of levels (M) no greater than 3 (i.e., M13), or some applications such as reactive and harmonic compensation in power systems, these multilevel converters do not require a separate dc power source to maintain each voltage level. The purpose of this paper is to increase the voltage level to achieve sinusoidal waveform & compare different voltage level by increasing the level through simulation. II. TOPOLOGIES OF MULTILEVEL INVERTER HAVE BEEN INVESTIGATED IN THE LITERATURE. A. Flying Capacitor Multilevel Inverter (FCMLI) Many capacitors are required which makes this topology heavy and cumbersome. In this, load cannot be directly connected to generate the zero voltage level. Instead, the zero level is obtained by connecting the load to the positive or negative bar through the flying capacitor with opposite polarity with respect to the dc-link [4] as shown in Fig.1a . Figure 1a.A 3-level flying capacitor inverter[4]
doi:10.22214/ijraset.2017.8327 fatcat:p4rjifgannalfaxlrndobcuiha