Power electronics

Power electronics are devices that convert electricity from one form to another. These devices control the electricity to convert electric power. Power electronics can include objects such as a battery charger for a laptop or solar panels connected to the electric grid. Power electronics have helped change human society, as they have led to the development of devices that can run off of converted electricity. These devices also have a great deal of promise for the future. Engineers believe they will help alternative energy sources, such as solar energy, better integrate onto the electric grid. The US Office of Energy Efficiency & Renewable Energy estimates that by 2030, roughly 80 percent of the electricity used in the United States will flow through power electronics. Humans’ increased reliance on power electronics has spurred innovation and has led to an increase in battery storage and improvements in power conversion. Creating efficient, long-lasting power electronics could help modernize the electrical grid and save money and resources in the process. The term power electronics can also be used to refer to the field of electrical engineering dealing with converting electrical power from one form to another.

Background

Electricity is a vital part of daily life. The technology used to create, deliver, and convert electricity is necessary for Americans to be able to use most of the devices that provide modern conveniences. Although scientists had studied electricity throughout history, they were not able to generate and convert it for personal use until the 1800s. In the 1830s, British scientist Michael Faraday discovered the basic system of generating electricity. Thomas Edison, working in his lab in the 1870s, created the first commercially useable incandescent electric light bulb, which helped make electricity a much sought after commodity. By the early 1900s, the first electrical grids were being built in the United States. Technological improvements made during the 1900s and 2000s have helped to dramatically increase the demand for and use of electricity in the United States. By 2022, Americans used an average of 4.7 trillion kilowatt-hours (kWh) of electricity each year.

Overview

Most engineers point to a 1902 invention as the beginning of the power electronics. The cathode mercury-arc rectifier was invented by American Peter Cooper Hewitt. It converted alternating current (AC) into direct current (DC). This invention helped people use electrical power in their homes. The mercury-arc rectifier was attached to a DC distribution line for the first time in 1905. In the 1930s, scientists at Westinghouse invented the ignitron tube, which was able to handle power at high voltages. In the 1950s, one new development in power electronics was the semiconductor diodes, which started replacing vacuum tubes. The silicon controlled rectifier (SCR) from General Electric also changed power electronics. Advancements in the 1960s helped increase the switching speed of transistors and allowed for high-frequency DC-DC converters.

Thyristor converters, introduced in the 1970s and still sometimes used in the 2020s, also helped revolutionize power electronics. These converters improved in 1995 to make them multilevel converters. This change allowed the converters to switch megawatts of power at a time, making them capable to become the main parts of high-voltage direct current (HVDC). HVDC and other advances made possible through power electronics have changed the modern electric grid. Today, people can convert electricity to different connected grids, to charge electric vehicles, to use renewable energy sources, to use in motor homes, and more. These applications of electricity are possible only because of the conversion done by power electronics.

Power electronics need a load and a source to be able to function. The load is the object or system to which the power electronic is transmitting the power. For example, think of a laptop charger. The laptop is the load in this case because the charger is converting the electricity from the source (which is the electricity going into the charger) and converting it before sending it to the laptop. Power electronic devices all have at least two terminals, as the electricity flows through the terminals in a circuit. Power electronics often reduce power as they convert it. This conversion is typically accomplished by switching states. Switching states can cause electricity to be lost in the process, which creates waste. Electrical engineers have worked to help reduce the waste associated with the conversion. Power electronics covert AC and DC power. A power electronic that does AC-AC conversion changes fixed AC voltage to a variable AC electrical signal. A DC-DC converter changes the DC signal to a variable DC voltage. An AC-DC converter, which is also called an inverter, change DC signals to AC signals.

The conversion from power electronics has changed the way people live because it has allowed many modern conveniences—such as computers and cell phones—to run off of the electricity people have in their homes. Furthermore, these converters have allowed people to use alternative energy sources, such as solar panels, to create electricity and put it back onto the public grid. It is likely that alternative power sources will become even more popular in the future. As a result, scientists have focused on creating devices that can efficiently and effectively convert power to and from the grid.

Scientists also believe that power electronics will help increase the reliability of the electrical grid. Advances in power electronics will allow the use of more distributed energy resources—such as solar farms—that are not as large as traditional power plants but that can still provide an important source of energy. Advancements in power electronics could also help the power grid because they can help implement new devices onto the grid.

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