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Power electronics

Power electronics is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Power electronics rather than just read about it. In short: Power electronics is the application of electronics to the control and conversion of electric power. The first high-power electronic devices were made using mercury-arc valves.

Power electronics — main illustration
Power electronics — illustration

Key takeaways

  • Power electronics belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Power electronics to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Power electronics from memory before moving on to harder problems.

Reference excerpt

Power electronics is the application of electronics to the control and conversion of electric power. The first high-power electronic devices were made using mercury-arc valves. In modern systems, the conversion is performed with semiconductor switching devices such as diodes, thyristors, and power transistors such as the power MOSFET and IGBT. In contrast to electronic systems concerned with the transmission and processing of signals and data, substantial amounts of electrical energy are processed in power electronics. An AC/DC converter (rectifier) is the most typical power electronics device found in many consumer electronic devices, e.g. television sets, personal computers, battery chargers, etc. The power range is typically from tens of watts to several hundred watts. In industry, a common application is the variable-speed drive (VSD) that is used to control an induction motor. The power range of VSDs starts from a few hundred watts and ends at tens of megawatts. The power conversion systems can be classified according to the type of the input and output power:

AC to DC (rectifier) DC to AC (inverter) DC to DC (DC-to-DC converter) AC to AC (AC-to-AC converter)

History Power electronics started with the development of the mercury-arc rectifier. Invented by Peter Cooper Hewitt in 1902, it was used to convert alternating current (AC) into direct current (DC). From the 1920s on, research continued on applying thyratrons and grid-controlled mercury-arc valves to power transmission. Uno Lamm developed a mercury valve with grading electrodes making them suitable for high-voltage direct current power transmission. In 1933 selenium rectifiers were invented. Julius Edgar Lilienfeld proposed the concept of a field-effect transistor in 1926, but it was not possible to actually construct a working device at that time. In 1947, the bipolar point-contact transistor was invented by Walter H. Brattain and John Bardeen under the direction of William Shockley at Bell Labs. In 1948 Shockley's invention of the bipolar junction transistor (BJT) improved the stability and performance of transistors, and reduced costs. By the 1950s, higher power semiconductor diodes became available and started replacing vacuum tubes. In 1956, the silicon controlled rectifier (SCR) was introduced by General Electric, greatly increasing the range of power electronics applications. By the 1960s, the improved switching speed of bipolar junction transistors had allowed for high-frequency DC/DC converters. R. D. Middlebrook made important contributions to power electronics. In 1970, he founded the Power Electronics Group at Caltech. He developed the state-space averaging method of analysis and other tools crucial to modern power electronics design.

Power MOSFET

In 1957, Frosch and Derick were able to manufacture the first silicon dioxide field effect transistors at Bell Labs, the first transistors in which drain and source were adjacent at the surface. Subsequently, Dawon Kahng led a paper demonstrating a working MOSFET with their Bell Labs team in 1960. Their team included E. E. LaBate and E. I. Povilonis who fabricated the device; M. O. Thurston, L. A. D'Asaro, and J. R. Ligenza who developed the diffusion processes, and H. K. Gummel and R. Lindner who characterized the device. In 1969, Hitachi introduced the first vertical power MOSFET, which would later be known as the VMOS (V-groove MOSFET). From 1974, Yamaha, JVC, Pioneer Corporation, Sony and Toshiba began manufacturing audio amplifiers with power MOSFETs. International Rectifier introduced a 25 A, 400 V power MOSFET in 1978. This device allows operation at higher frequencies than a bipolar transistor, but is limited to low voltage applications. The power MOSFET is the most common power device in the world, due to its low gate drive power, fast switching speed, easy advanced paralleling capability, wide bandwidth, ruggedness, easy drive, simple biasing, ease of application, and ease of repair. It has a wide range of power electronic applications, such as portable information appliances, power integrated circuits, cell phones, notebook computers, and the communications infrastructure that enables the Internet. In 1982, the insulated-gate bipolar transistor (IGBT) was introduced. It became widely available in the 1990s. This component has the power handling capability of the bipolar transistor and the advantages of the isolated gate drive of the power MOSFET.

Devices

… excerpt ends here. Continue reading the full article.

Illustrations

Power electronics: An HVDC thyristor valve tower 16.8 m tall in a hall at Baltic Cable AB in Sweden
An HVDC thyristor valve tower 16.8 m tall in a hall at Baltic Cable AB in Sweden
Power electronics: A battery charger is an example of a piece of power electronics.
A battery charger is an example of a piece of power electronics.
Power electronics: A PC's power supply is an example of a piece of power electronics, whether inside or outside of the cabinet.
A PC's power supply is an example of a piece of power electronics, whether inside or outside of the cabinet.
Power electronics: Figure 8: The AC input for an ASD
Figure 8: The AC input for an ASD
Power electronics: Figure 9: Single-phase half-bridge voltage source inverter
Figure 9: Single-phase half-bridge voltage source inverter

Worked examples

Example 1 — a first encounter with Power electronics

Start with the simplest possible case. Write down what Power electronics claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Power electronics before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Power electronics ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Power electronics

In research
Power electronics appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Power electronics in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Power electronics is common in secondary-school and first-year university syllabi. It links to neighbouring topics Electronics industry, Power electronics, so understanding it makes those chapters shorter.
In everyday life
Look for Power electronics outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Power electronics in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Power electronics means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Power electronics out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Power electronics in simple terms?

Power electronics is the application of electronics to the control and conversion of electric power. The first high-power electronic devices were made using mercury-arc valves.

Why does Power electronics matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Power electronics?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Power electronics.

Tags

  • Electronics industry
  • Power electronics

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