Page 336 - A Comprehensive Guide to Solar Energy Systems

Chapter 16 • Small-Scale PV Systems Used in Domestic Applications 341

FIGURE 16.6 The details of four primary power stages of a voltage-sourced grid-tied inverter.

FIGURE 16.7 The details of a self-commutated current-sourced grid-tied inverter with a series inductor.

16.3.3 Emerging Converter Topologies
16.3.3.1 Cascaded Multilevel Modular Integrated Converters in Small-scale Grid-Tied
PV Systems [1,4]
A hybrid of the central inverter and the micro inverter is known as a cascaded inverter,
and effectively is a set of multiple h-bridges in a cascaded configuration with the grid.
Cascaded multilevel modular integrated converters (MICs) (decentralized or not) have a
multitude of various factors affecting their performance. Changing the number of MICs in
a cascaded system has an effect on the transistor efficiency, capacitor reliability, switching
frequency, fault tolerance, modularity, MPPT capability, voltage gain requirements, and
ease of installation. The filter design is also affected by the cascaded nature of the system.
As it can be seen in Fig. 16.8, each MIC has five primary components, which are the PV
panel, boost converter, h-bridge, output filter, and controller. The PV panel, when paired
with the boost converter, produces a constant DC output voltage while allowing for MPPT.
The controller, which controls the boost converter, also coordinates the transistors of the
h-bridge to inject the correct amount of power through the filter and into the grid to sat-
isfy the PV, MPPT, and grid harmonic requirements. In this topology, each MIC requires