Saturday, September 1, 2018

Power Electronics


What is Power Electronics?

Power electronics is a part of electrical engineering that includes control, conditioning and transformation of electric power using semiconductor devices like; FETs, SiC, GaN and passive components like; resistors, inductors and capacitors. Semiconductor devices used for switching and control. Passive components used for sensing and filtering.

In other words we can say that, power electronics is the use of solid-state electronic components like; transistor, diodes, integrated circuits, etc. to the control and conversion of electric power.

Power Electronics
An assembled Power Converter Circuit

Difference between Electronics and Power Electronics

Electronics means study of flow of electrons in electrical circuits i.e. in this we learn how an electron behaves under different conditions of externally applied fields.

Purpose of Electronics is to handle data signals by the means of amplifier, oscillator, filters, audio & video transmitters and receivers etc. We can also say that it deals with signal processing instead of power conversion. Here transistor works in active region.

Though in Power Electronics, the attention is more on productive use of electrical power. This system uses converters like; rectifiers and inverters to control load operation by providing proper voltage and current. Here transistor works in cut-off or saturation region.

Power Electronics
Three Segments of Power Electronics

Importance of Power Electronics

Power Electronics is important because different types of systems require different types of power. For example, your average microcontroller would require about 3.3V of DC voltage but your mains would supply only voltage 230V, 50Hz AC. In these cases, you would need a converter or rectifier to rectify the mains to a DC voltage.

Power Electronics use is in high voltage applications, such as connecting two power systems of a different frequency.

Power Electronics is completely essential to incorporate renewable energy with power systems. It is required to connect renewable energy sources to conventional power grids because such energy sources like solar cells and wind turbines do not produce electric power that is well-suited with today’s power grids.

Semiconductors used in Power Electronics

Different types of semiconductors (usually dived in three groups) have been used in Power Electronics;

Power Electronics
Power Electronics Devices
Diodes – They are used in rectifiers, dc–dc converters, and carries current in only one direction and always blocks current in the other direction.

Transistors – These are appropriate for control of single-polarity circuits. Several forms of transistors are applied to power converters. One of the type is IGBT which is unique to power electronics and has good features for applications such as DC to AC inverters.

Thyristors – These are multi-junction semiconductor devices with latching behaviour. In general, thyristors can be switched ON with small pulses and then keep their state same until current is removed. They perform only as a switch. The features are mainly well suitable to high-power controllable rectifiers; they have been useful to all power-conversion applications.

Examples of Semiconductor Devices used in Power Electronics

Below mentioned components are mostly used in Power Electronics;

Diode = It carries current in only one direction and always blocks current in the other direction. Applications are ac to dc rectifiers and dc to dc circuits.

BJT = Bipolar Junction Transistor. It conducts collector current (in one direction) when sufficient base current is applied. The application applies to dc–dc circuits.

FET = Field effect transistor. It conducts drain current when sufficient gate voltage is applied. The application applies to dc–dc conversion, where the FET is in wide use, and to inverters.

IGBT = Insulated gate bipolar transistor. It is a special type of transistor that has the function of a BJT with its base driven by an FET. It is faster than a BJT of similar ratings, and easy to use. The IGBT is popular in inverters.

SCR = Silicon-controlled rectifier. It is a thyristor that conducts like a diode after a gate pulse is applied. It turns off only when current becomes zero. It prevents current flow until a pulse appears. It is widely used for controlled rectifiers.

GTO = Gate turn-off thyristor. It is a SCR that can be turned off by sending a negative pulse to its gate terminal.

TRIAC =Triode for Alternating Current. It is a semiconductor constructed to resemble two SCRs connected in reverse parallel. It is used in many AC applications like; lamp dimmers, home appliances, and hand tools.

IGCT = Integrated gate commutated thyristor. It is a combination device that includes a high-power thyristor and external electronics to control it. This device is a member of a larger family of combination devices, in which multiple semiconductor chips packaged together perform a single power function.

Power Electronics
Power Electronics Components

Power Electronics Applications

Power Electronics applications varies from high power conversion equipment such as dc power transmission to daily appliances, such as wireless screwdrivers, power supplies for computer systems, mobile phone chargers, lighting systems and electric vehicles.

Power electronics can process milliwatts or Megawatts applications easily Usual applications of power electronics contains conversion of AC to DC, conversion of DC to AC, transformation of an unregulated DC voltage to a regulated DC voltage and transformation of an AC power source from one amplitude and frequency to a different amplitude and frequency.

Power electronics includes applications of circuit theory, control theory, electronics, electromagnetics, microprocessors or microcontrollers (for control) and heat transfer.

Conclusion

Power Electronics progresses in its every application field. The main reason behind this is advancement of semiconductor switching components, filter components, controlling components, ferrite materials and other electronic components. These developments improve the efficiency and performances of electrical and electronic devices and have made power electronics a significant and fast-growing area in electrical and electronics engineering.

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Hi, welcome to my blog, “Power Electronics Talks”.

I am an Electronics Engineer. I am passionate about Power Electronics and latest Technology. By profession I am design and application engineer and play with circuits.

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