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.
