I am proudly presenting this special issue to the professional communities of the world. Power electronics is an extremely important element in modern smart grid and renewable energy systems. Basically, it uses high-efficiency switching power semiconductor devices to convert and control electrical power with the help of dc-to-dc, dc-to-ac, ac-to-dc, and ac-to-ac converters that are applied extensively in industrial, commercial, residential, transportation, aerospace, military, and utility systems. Power electronics plays significant role in modern industrial automation and high-efficiency energy systems that include renewable energy systems (such as wind and photovoltaic), bulk energy storage, electric and hybrid vehicles, and energy-efficiency improvement of electrical equipment. In modern electric power grid, power electronics is indispensable in high-voltage dc (HVDC) system, static VAR compensators (SVCs), flexible ac transmission system (FACTS)-based active and reactive power flow control, uninterruptible power system (UPS), fuel-cell-based energy system, etc. After a dynamic technology evolution for nearly five decades, power electronics has now grown possibly as the most important technology in the 21st century. Currently, most of our energy comes from fossil fuels and nuclear power plants. Fossil fuels cause environmental pollution that causes global warming or climate change problems. Nuclear energy is clean in that respect, but it has safety and radioactive waste disposal problems. For these reasons, the whole world is now turning toward renewable energy, where power electronics is an indispensable ingredient.

The paper is basically an introduction of power electronics and its applications with emphasis on renewable energy systems and smart grid. The advent of modern power electronics has brought tremendous impact on power systems, besides the usual industrial applications to improve productivity. Power electronics is possibly the most important element in modern smart grid and renewable energy systems. The discussion in the paper will include modern power semiconductor devices and applications of power electronics in energy saving, electric vehicles, renewable energy systems, and grid energy storage. Finally, the basic elements of smart grid will be reviewed.

Artificial intelligence (AI) techniques, such as expert systems (ESs), fuzzy logic (FL), and artificial neural networks (ANNs or NNWs) have brought an advancing frontier in power electronics and power engineering. These techniques provide powerful tools for design, simulation, control, estimation, fault diagnostics, and fault-tolerant control in modern smart grid (SG) and renewable energy systems (RESs). The AI technology has gone through fast evolution during last several decades, and their applications have increased rapidly in modern industrial systems. This special issue will remain incomplete without some discussion on AI applications in SG and RESs. The paper will discuss some novel application examples of AI in these areas. These applications are automated design of modern wind generation system and its health monitoring in the operating condition, fault pattern identification of an SG subsystem, and control of SG based on real-time simulator. The concepts of these application examples can be expanded to formulate many other applications. In the beginning of the paper, the basic features of AI that are relevant to these applications have been briefly reviewed.

Artificial intelligence (AI) tools, such as expert systems, fuzzy logic, and neural networks are expected to usher a new era in power electronics and motion control in the coming decades. Although these technologies have advanced significantly and have found wide applications, they have hardly touched the power electronics and machine drives area. The paper describes these AI tools and their application in the area of power electronics and motion control. The body of the paper is subdivided into three sections which describe, respectively, the principles and applications of expert systems, fuzzy logic, and neural networks. The theoretical portion of each topic is of direct relevance to the application of power electronics. The example applications in the paper are taken from the published literature.>

A comprehensive review of power electronics technology that includes a discussion of power semiconductor devices, topologies of different classes of converters, and some selected applications is given. The modern power semiconductor devices that appeared in the 1980s, i.e., IGBTs, SITs, SITHs, and MCTs, are emphasized. Tables comparing the numerical ratings of the devices are included. Although modern converters are emphasized, phase-controlled converters, which are now very commonly used, are included for completeness. Tables comparing the features of AC-AC converters, particularly for AC drive applications are given. A few selected applications indicate in general the complexity of power electronics systems.>