In a simple way, we define power electronics as a science dedicated to the study and development of static electricity converters, such as frequency inverters, rectifiers and DC-DC converters, aiming at maximum efficiency and quality in the transformation processes of electric energy, reducing the number of losses and interferences in energy conversion processes, as well as technologies linked to clean energy sources such as photovoltaic and wind power. The emergence of power electronics and drives provided an alternative that brought advantages for power processing, thanks to the little need for maintenance of the semiconductor switches and along with low power loss in switching.
Power electronics came in around and for a few decades, there was little evolution, because the technology of switching devices available at the time was expensive, very bulky and unreliable. With the invention of the thyristor, began the great technological growth of Power Electronics. During this phase of growth, the theoretical bases of the Power Electronics were launched, with numerous researches and development works. Since then the field of applications of Power Electronics has been growing more and more. The main purpose of power electronics is to process and control the flow of electrical energy, using semiconductor devices operating as switches, to control the flow of electricity and conversion of waveforms of voltages and currents between sources and charges. The main semiconductor switches are diodes, bipolar transistors, SCR's, GTO's, MOSFET and IGBT's.
Static converters are electronic devices that convert energy without using mobile components, defined as a system consisting of passive elements such as resistors, capacitors and inductors and the active element which are switches. There are several types of converters, such as the chopper that transforms fixed voltage DC to variable voltage DC, there is the AC voltage controller, which transforms AC from fixed voltage to AC of variable frequency and voltage, in addition to the cycle converters, which transform AC from fixed frequency into AC of varying frequency and voltage. There are rectifiers, which transform alternating current into direct current and inverters, which transform direct current into alternating current. There are a excess of applications for power electronics such as switched power supplies, control of alternating and direct current motors, emergency power, battery chargers, power transmission, electronic ballasts, active filters, static compensators, alternative energy processing, power amplifiers, temperature controls, lighting, aircraft power system, AC drive, household utilities, robotics, drive systems for electric and hybrid vehicles, dc charging stations and other applications.
A large part of power electronics is used in the industrial area, such as power transmission over long distances in direct current, electric drives, electric traction, uninterrupted power sources, and can be used in the building area as well as building automation, as control of temperature, lighting, security systems, in addition to photovoltaic energy production. It has the advantage of not causing leaks in the system, limiting the starting current, avoiding current spikes and still incorporate smooth stop and protections. These keys contribute to reduced stress on couplings and transmission devices during startup and to increase the life of the engine and mechanical equipment of the driven machine due to the elimination of mechanical shocks.
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