What are Power Electronics?
The goal of an energy conversion process is to best serve the needs of a consumer, while supporting highly efficient generation and transport of energy. Consider a few subdiciplines of electrical engineering, with their conversion roles:
- Signal processing engineers consider conversions between information and electricity.
- Antenna engineers consider the most efficient, reliable ways to convert the energy in electromagnetic waves into circuit currents and voltages.
- Electromechanics engineers consider conversions between mechanical and electrical energy forms.
- Quantum electronics engineers often concern themselves with the interaction of optical signals with electronic circuits.
There are many other examples, but the basic issue has been left out: What about conversion, with emphasis on energy flow, among the various forms of electrical sources? This is the framework of power electronics. Power electronics engineers design circuits to convert electrical energy among its many useful forms. The discipline is defined in terms of electrical energy conversion, applications, and electronic devices. This suggests that power electronics is one of the broadest subdisciplines of electrical engineering. Many students find that the study of power electronics shows them how electrical engineering fits together as a cohesive discipline.
It is helpful to have a more specific definition. Power electronics involves the study of electronic circuits intended to control the flow of electrical energy. These circuits handle power flow and levels much higher than the individual device ratings.
The subject represents a median point combining topics in energy systems, electronics, and control. In the study of electrical engineering, power electronics must be listed on a par with digital electronics, analog electronics, and radio-frequency electronics to reflect its distinct nature.
Although power electronics stands distinct from other electronics areas, most students and engineers have some familiarity with a few of the major applications. Rectifiers, or circuits for ac to dc conversion, are well-known examples of energy conversion circuits. Since the 1960s, new semiconductor technologies have dramatically broadened practical possibilities for conversion circuits. A universal characteristic of power electronic circuits is that they manage the flow of electrical energy between some sort of source and a load. The parts in a circuit must direct electrical flows, not impede them. Small components able to manipulate heavy energy flows are of interest, analogous to valves in a plumbing system.
Power electronics designers tend to look mainly at voltage and current ratings of a device. Semiconductors of modest size can handle the energy levels in a typical home or commercial establishment. Semiconductor circuits for lighting, industrial motors, and even locomotives are in regular use.
High-power applications lead to some interesting issues. For example, in an inverter, the semiconductors often manipulate 20 times their rated power or more. A small change might put large additional stresses on the devices, leading to quick and catastrophic failure. The flip term ‘smoke test’ has a clear and direct meaning when the circuit under test is a power converter. The associated excitement leads to a black magic view of the subject. Many engineers find out the hard way that power semiconductors make fast, but expensive, fuses.