Multi level inverters topologies and their simulation in Matlab/Simulink

In this study, a review of cascaded H-bridge multilevel inverter topology and control schemes was conducted. Multilevel inverter topology (MLI) H-bridge cascade is implemented to reduce harmonic for high power applications. Applications of multilevel converters are able to reduce the number of harmonics contained in the system of low-voltage electrical distribution. Each topology has their own advantages and disadvantages. The cascaded H-bridge multilevel inverter topology requires only a single DC power source with both input and output, high availability, and the control of power flow in the regenerative version. The selected switching technique to control the inverter will also have an effective role on harmonic elimination while generating the ideal output voltage. Intensive studies have been performed on carrier-based, sinusoidal, space vector and sigma delta PWM methods in open loop control of inverters. The results from this study represent a beneficial basis for matching of inverter topology and the best control scheme according to different application areas. In general, increasing the switching frequency in voltage source inverters (VSIs) leads to better output voltage and current waveforms. Harmonic reduction in controlling a VSI with variable amplitude and frequency of the output voltage is important, and thus, conventional inverters which are referred as two-level inverters require increased switching frequency along with various PWM switching strategies. The multilevel fundamental switching scheme is used to control the needed power electronics switches. Also, a method is presented where switching angles are computed such that a desired fundamental sinusoidal voltage is produced and at the same time certain higher order harmonics are eliminated. The generalized multilevel inverter topology can balance each voltage level by itself regardless of the inverter control and load characteristics. The concept of multilevel converters has been introduced since 1975. The usage of these applications has become more diverse and affects a wide field of electrical engineering from a few watts to several hundred megawatts. Converting static structures that comprise mainly applications of power electronics is becoming increasingly powerful, and the technology has had to adapt to the growth of the power to convert. Multilevel inverter topologies are the Neutral-Point Clamped (NPC) inverters (or DiodeClamped inverters), the cascaded H- bridge inverters (CHB), and the Flying Capacitor (FC) inverters (or Capacitor Clamped inverters), as shown in Figure 1. In this paper, a review of multilevel inverter based on cascaded h-bridge topology and control schemes was conducted. The advantages of this multilevel approach include good power quality, good electromagnetic compatibility (EMC), low switching losses, and high voltage capability.