Energy Balance Control of a Cascaded Multilevel Inverter for Standalone Solar Photovoltaic Applications

Abstract

This paper presents a clock phase-shifting (CPS) energy balance control (EBC) method for cascaded half-bridge multilevel inverters in standalone solar photovoltaic (PV) systems. It is based on the conservation of energy in each cascaded unit. By shifting the phase of the clock pulse of each cascaded unit, a staircase-like output voltage is obtained. The CPS EBC not only regulates the staircase-like output voltage of the cascaded multilevel inverters accurately under static conditions, but also suppresses the fluctuations of DC sources and improves its dynamic responses to load steps. Thus, the problems existing in solar PV systems using the cascaded multilevel inverters are avoided. Results obtained from simulations and experiments are presented to verify the feasibility and advantages of the proposed control method.

Fault‐tolerant modular multilevel converter for a seamless transition between stand‐alone and grid‐connected microgrid

“… $$$$\begin{equation}\alpha = \left( {\frac{{{{180}}^\circ }}{{N - 1}}} \right)\ \end{equation}$$$$where N is the voltage level from 0 to positive peak, and in this case, N equals 21, and the phase displaced angle is 9°. When the unipolar scheme is used, the carriers are compared with the 50‐Hz sinusoidal reference and its 180° anti‐phase part to decide PWM switching times [18, 19]. The first carrier applied for phase A upper first SM has been highlighted for observation as shown in Figure 5.…”

Design and Implementation of a New Multilevel Inverter Employing Reduced Components

“…This topology is considered for comparisons by " 1 R ". Another topology is presented in [22] which offers symmetry and asymmetry from its structure is described in " 2 R ". [33] which is described by " 9 R ".…”

“…Each one of these topologies has merits and demerits due to the number of used components such as power switches and DC voltage sources, power losses and voltage stress on the switches. Using a large number of power switches, gate drive circuits in [22] leads to increased circuit size and manufacturing costs. By using the bidirectional switches to obtain more number of levels, the number of power switches and drive circuits in [23] is reduced.…”

“…In order to overcome the aforementioned issues, a new multilevel inverter has been presented in this paper. The proposed topology has an optimum number of power components and hence fewer gate drive circuits in addition to less circuit layout complexity for a high number of levels compared with other topologies mentioned in [22] Figure 1 shows a modified structure for the proposed single-phase MLI which reduces the overall circuit by one power switch compared with the proposed circuits in [26] [27]. The proposed MLI comprises of "n" segments each segment is composed of a DC voltage source in series with one power switch without fast recovery diode.…”

Optimized RNN-oriented power quality enhancement and THD reduction for micro grid integration of PV system with MLI: Crow Search-based Harris Hawks Optimization concept

“…This raises the PWM's intricacy and necessitates more computing power. Low switching frequency approaches, in which the needed switching angles are predicted previously, can be, employed rather (Wang et al, 2017). They want to produce a waveform that nearly mimics a pure sinusoid by obtaining the most precise switching angles.…”