Neon lighting:

Introduction:

Neon lighting comprises of brightly illuminating glass tubes or bulbs that have been electrified and are filled with rarefied neon or other gases. A kind of cold cathode gas discharge light is a neon light. A sealed glass tube with a metal electrode at each end that is filled with one of many gases under low pressure is known as a neon tube. The electrodes are subjected to a high potential of several thousand volts, which ionises the gas inside the tube and causes it to generate colourful light. The gas inside the tube determines the hue of the light.Neon tubes can be crafted into curved creative shapes that can be used to create letters or images. They are mostly used to create neon signs, which were popular from the 1920s to the 1960s and again in the 1980s. Neon signs are spectacular, multicoloured glowing signage for advertising.

 

Neon lighting

The phrase can also be used to describe the tiny neon glow lamp, which was created in 1917—roughly seven years after neon tube lighting.

 

Unlike neon tube lights, which are normally metres long, neon lamps can be as small as one centimetre and glow considerably more subtly. They continue to be used as tiny indication lights. Neon glow lamps were widely utilised for small ornamental lamps, electronic numerical displays, and circuitry signal processing during the 1970s.

 

Although these lamps are now considered antiques, plasma displays and modern televisions were made using neon glow lamp technology.

 

The British physicists Morris W. Travers and William Ramsay discovered neon in 1898. Through the use of a "electrical gas-discharge" tube, a precursor to the tubes used for neon signs today, they first extracted pure neon from the environment and studied its properties. At the Paris Motor Show, held from December 3–18, 1910, French engineer and inventor Georges Claude unveiled neon tube lighting in virtually its contemporary form. In the years between 1920 and 1940, the new technology—often referred to as "the Edison of France"—became extremely popular for signage and exhibitions. Claude enjoyed a near-monopoly on this market.

 

By 1940, neon lights had become a significant part of American culture. Nearly every American city's downtown was lit up with neon signs, and Times Square in New York City was renowned for its extravagant use of neon. Nationwide, there were 2,000 businesses that created and manufactured neon signs. Following the Second World War (1939–45), neon signage for advertising became less common, intricate, and large-scale in the United States, while development was brisk in Japan, Iran, and some other nations. In recent years, neon tube lighting has been reintroduced into the works of architects, painters, and sign designers.

 

Fluorescent lighting, which emerged roughly 25 years after neon tube lighting, is closely related to neon lighting. In fluorescent lighting, the light emitted by rarefied gases inside a tube is only utilised to stimulate fluorescent materials that coat the tube. When these materials shine with their own colours, it creates the tube's apparent glow, which is typically white. Although fluorescent coatings and glasses offer an alternative for neon tube lighting, they are typically chosen to achieve vivid colours.

 

Science and history:

A small amount of the atmosphere on Earth is made up of the inert gas neon, a chemical member of the noble gas family. William Ramsay and Morris W. Travers, two British physicists, made the discovery in 1898. Ramsay and Travers employed a "electrical gas-discharge" tube, which is akin to the tubes used today for neon signs, to study the properties of pure neon after they were successful in extracting it from the environment. The blaze of crimson light emanating from the tube, Travers later penned, "told its own story and was a sight to dwell upon and never forget."Since the colours of light (the "spectral lines") emitted by a gas discharge tube are essentially fingerprints that identify the gases inside, the process of studying the colours of the light emitted from gas-discharge (or "Geissler") tubes was widely known at the time.

 

Neon tubes were utilised as scientific instruments and novelty items as soon as neon was discovered. Although Moore tubes, which utilised more widely available nitrogen or carbon dioxide as the working gas and had some commercial success in the US in the early 1900s, employed neon as the working gas, the lack of pure neon gas prevented its fast deployment for electrical gas-discharge lighting.After 1902, the French company Air Liquide founded by Georges Claude started manufacturing large amounts of neon as a byproduct of the air liquefaction industry. At the Paris Motor Show from December 3 to December 18, 1910, Claude displayed two substantial, bright red neon tubes measuring 12 metres (39 feet) in length.

 

Essentially, these neon bulbs were in their modern configuration. The glass tubes used in neon lighting have exterior diameters that range from 9 to 25 mm, and they can be as long as 30 metres when powered by normal electrical equipment (98 ft). The partial vacuum in the tubing is caused by the gas's pressure, which varies from 3 to 20 Torr (0.4 to kPa) within. Additionally, Claude had found solutions to two technical issues that significantly reduced the operating lifespan of neon and other gas discharge tubes, effectively creating the neon lighting industry.

 

The design of the electrodes for gas-discharge lighting was the subject of Claude's 1915 US patent, which served as the foundation for the neon sign monopoly that his business, Claude Neon Lights, had in the US during the first few years of the 1930s.

 

In his inventions, Claude proposed using gases like argon and mercury vapour to achieve hues other than those of neon. For instance, blue is produced when metallic mercury and neon gas are combined. Then, uranium (yellow) glass can be used to create green. Argon and helium can also be used to produce white and gold.

 

The range of colours and effects for tubes using argon gas or argon-neon mixtures was further expanded in the 1920s with the development of fluorescent glasses and coatings. Typically, fluorescent coatings are used with an argon/mercury vapour mixture, which emits ultraviolet light that activates the fluorescent coatings. By the 1930s, neon tube light colour combinations were successful in Europe but not in the US. They were now suitable for some general interior lighting applications. Since the 1950s, approximately 100 new hues for neon tube lighting have been produced thanks to the development of phosphors for colour televisions.

 

Neon lighting

The tiny neon lamp was created by Daniel McFarlan Moore, who was then employed by General Electric, in the early 1920s. The design of the glow lamp differs significantly from the much larger neon tubes used for signage; in 1919, a separate US patent was granted for the lamp. "These compact, low power devices exploit a physical mechanism termed "coronal discharge,"" according to a Smithsonian Institution website. Moore put neon or argon gas into a bulb with two electrodes placed closely together. Depending on the gas, the electrodes would emit a brilliant red or blue glow, and the lamps would survive for years.

 

Fanciful decorative lamps have been a popular application since the electrodes might assume practically any shape imaginable. Until the advent of light-emitting diodes (LEDs) starting in the 1970s, glow lamps were used in practical ways as electrical components, indicators in instrument panels, and in many home appliances.

 

Although certain neon lamps are now considered antiques and their application in electronics has significantly decreased, the technology has continued to advance in the realms of art and entertainment. Long tubes used for neon lighting have been transformed into thin flat panels for plasma displays and plasma televisions.

 

 

 

 

Electronic engineering:

Introduction:

The early 20th century saw the emergence of the subfield of electrical engineering known as electronics engineering. It is defined by the extra use of active components like semiconductor devices to amplify and regulate electric current flow. Until recently, passive components like mechanical switches, resistors, inductors, and capacitors were the only ones utilised in electrical engineering.

 

Electronic engineering

It includes topics like power electronics, embedded systems, consumer electronics, digital electronics, and analogue electronics. It also has a significant presence in a number of allied subjects, including solid-state physics, radio engineering, telecommunications, control systems, signal processing, systems engineering, computer engineering, instrumentation engineering, electric power control, and robotics.

 

One of the most significant professional organisations for electronics professionals is the Institute of Electrical and Electronics Engineers (IEEE), which is also known as the Institution of Engineering and Technology in the UK (IET). Electronic engineering electrical standards are published by the International Electrotechnical Commission (IEC).

 

The past and present:

Following the discovery of the electron in 1897 and the subsequent development of the vacuum tube, which could amplify and rectify minuscule electrical impulses, the discipline of electronics was introduced, and electronic engineering as a career arose. Ambrose Fleming and Lee De Forest's inventions of the diode and triode in the early 1900s opened the door for practical applications since they allowed for the non-mechanical detection of modest electrical voltages like radio signals from a radio antenna. Electronics experienced a quick expansion. Early in the 1920s, commercial radio broadcasting and communications had spread widely, and a variety of uses for electronic amplifiers had emerged, including long-distance telephony and the music recording industry.

 

The extensive development of electronic equipment during World War II, including radar and sonar, as well as the ensuing consumer revolution during peacetime, significantly improved the discipline.

 

Specialized fields:

There are numerous subfields in electronic engineering. The most well-known are described in this section.

 

Analyzing and modifying signals is the subject of electronic signal processing. Signals can be either analogue or digital, with the former varying continuously in accordance with the information while the latter fluctuates in accordance with a series of discrete values that correspond to the information.

 

 

 

Signal processing for analogue signals can include radio frequency signal modulation and demodulation for telecommunications as well as audio signal amplification and filtering for audio equipment. Signal processing for digital transmissions may include compression, error checking, error detection, and error correction.

 

Information transfer via a medium, such as a coaxial cable, an optical fibre, or free space, is the subject of telecommunications engineering. Information must be encoded in a carrier wave for transmission across empty space; this process is referred to as modulation. Amplitude modulation and frequency modulation are two common types of analogue modulation.

 

Telecommunication engineers design the transmitters and receivers required for such systems after the transmission characteristics of a system are established. A transceiver, a two-way communication device, is occasionally created by combining these two. The power consumption of transmitters is an important factor to take into account throughout the design process because it is closely related to the signal intensity.A transmitter's insufficient signal strength will cause noise to tamper with the signal's information.

 

Aerospace applications are the focus of aviation-electronic engineering and aviation-telecommunications engineering. Engineers in aviation and telecommunications may also be experts in ground-based or airborne avionics. Computer, networking, IT, and sensor knowledge are the most important skills for specialists in this industry. Such colleges as Civil Aviation Technology Colleges provide these courses.

 

From the flight and propulsion systems of commercial aeroplanes to the cruise control found in many contemporary cars, control engineering is used in a wide variety of electronic applications. It is crucial to industrial automation as well. Feedback is a common tool used by control engineers while creating control systems.

 

Designing instruments to monitor things like pressure, flow, and temperature is the domain of instrumentation engineering.

 

Such instruments need to be designed with a solid understanding of electronic engineering and physics; radar guns, for instance, use the Doppler effect to gauge the speed of approaching vehicles. The Peltier-Seebeck effect is also used by thermocouples to gauge temperature differences between two sites.

 

Instrumentation is frequently utilised as the sensors of bigger electrical systems rather than by itself. For instance, a thermocouple could be used to help maintain a furnace's constant temperature. Because of this, control engineering and instrumentation engineering are frequently seen as complementary disciplines.

 

Designing computers and computer systems is the focus of computer engineering. This could involve developing new computer gear, creating PDAs, or using computers to manage an industrial facility. This field also includes the creation of embedded systems, or systems designed for particular purposes (such as mobile phones). The microcontroller and its applications fall under this category. The software of a system may also be developed by computer engineers.

 

Engineering VLSI design Very large scale integration is known as VLSI. It deals with the production of ICs and different electronic parts. Electronics engineers first create circuit schematics, which list the electrical components and explain how they are connected, before building an integrated circuit. Once finished, VLSI experts turn the schematics into layouts that depict the layers of different semiconductor and conductor materials required to build the circuit.

 

Electronic engineering

 

Education and training:

A branch of the larger academic field of electrical engineering is called electronics. Electronic engineering is a common major for academic degrees held by electronics engineers. Depending on the university, the degree earned after completing the required three or four years of study may be known as a Bachelor of Engineering, Bachelor of Science, Bachelor of Applied Science, or Bachelor of Technology. Graduate-level Master of Engineering (MEng) degrees are also offered by many UK universities.

 

Some electronics engineers additionally decide to pursue a postgraduate degree, such as an engineering doctorate, master of science, or doctor of philosophy in engineering. In several American and European universities, the master's degree is being offered as the first degree, and it might be challenging to distinguish between an engineer with graduate and postgraduate studies. Experience is taken into consideration in certain situations. Research, coursework, or a combination of the two may make up a master's degree. The doctor of philosophy degree, which frequently serves as a stepping stone into academia, includes a sizeable portion of research.

 

The initial step for certification in the majority of nations is a bachelor's degree in engineering, and the degree programme itself is accredited by a professional body. Engineers can legally certify designs for initiatives compromising public safety when they are certified. The engineer must fulfil a number of requirements after finishing a certified degree programme, including work experience requirements, before being certified. Professional Engineer (in the US, Canada, and South Africa), Chartered Engineer or Incorporated Engineer (in the UK, Ireland, India, and Zimbabwe), Chartered Professional Engineer (in Australia and New Zealand), or European Engineer are the titles given to engineers when they have been certified (in much of the European Union).

 

The majority of degrees in electronics contain courses in physics, chemistry, arithmetic, project management, and certain areas of electrical engineering. These subjects initially cover the majority, if not all, of the electronic engineering subfields. Towards the end of their degree, students then decide whether to specialise in one or more subfields.

 

Physics and mathematics are fundamental to the field since they aid in obtaining both a qualitative and quantitative description of how such systems will function. Nowadays, computers are used for the majority of engineering labour, and building electrical systems frequently makes use of computer-aided design and simulation tools. Although the majority of electronic engineers are familiar with fundamental circuit theory, engineers typically use different theories depending on the type of work they conduct. For instance, whereas solid state physics and quantum mechanics may be pertinent to an engineer working on VLSI, they are generally unimportant to engineers working with embedded systems.

 

Electronic engineering

Other topics on the syllabus, besides electromagnetics and network theory, are exclusive to the electronics engineering degree. Other areas of focus in electrical engineering courses include machines, power generation, and distribution. The substantial engineering mathematics programme that is a requirement for a degree is not included in this list.

 

 

 

Power electronics:

Introduction:

The use of electronics in the conversion and control of electric power is known as power electronics.

 

Power electronics

Mercury-arc valves were used to create the first high-power electronic gadgets. In contemporary systems, the conversion is carried out by power transistors like the power MOSFET and IGBT and other semiconductor switching devices such diodes, thyristors, and diodes. In contrast to electronic systems that deal with the transmission and processing of signals and data, power electronics processes a significant amount of electrical energy.The most prevalent power electronics component present in many consumer electronics products, such as television sets, personal computers, battery chargers, etc., is an AC/DC converter (rectifier). Tens of watts to several hundred watts is the usual power range. The variable speed drive (VSD), which is used to regulate an induction motor, is a popular use in the industrial sector. VSDs have a power range that ranges from a few hundred watts to tens of megawatts.

 

The kind of input and output power can be used to categorize power conversion systems:

a) Ac to Dc (rectifier)

b) Dc to Ac  (inverter)

c) Dc to Dc (DC-to-DC converter)

d) Between AC (AC-to-AC converter)

 

Power electronics

History:

The mercury arc rectifier was the first power electronic device. It was created in 1902 by Peter Cooper Hewitt to change alternating current (AC) into direct current (DC). Thyratrons and grid-controlled mercury arc valves for power transmission have been studied since the 1920s. Mercury valves with grading electrodes were created by Uno Lamm to be used for high voltage direct current power transmission. Selenium rectifiers were created in 1933.

 

Field-effect transistors were first conceptualized by Julius Edgar Lilienfeld in 1926, but no practical devices could be built at that time. Walter H. Brattain and John Bardeen created the bipolar point-contact transistor in 1947 at Bell Labs with the help of William Shockley. The bipolar junction transistor (BJT), developed by Shockley in 1948, increased the stability and performance of transistors while lowering their price. Higher power semiconductor diodes became accessible in the 1950s and began to take the place of vacuum tubes. The field of power electronics applications was significantly expanded in 1956 when General Electric released the silicon controlled rectifier (SCR). High frequency DC/DC converters were made possible by the improved switching speed of bipolar junction transistors by the 1960s.

 

Power electronics benefited greatly from R. D. Middlebrook's innovations. He started the Power Electronics Group at Caltech in 1970. Along with other techniques essential to contemporary power electronics design, he created the state-space averaging method of analysis.

 

Power MOSFET:

The development of the MOSFET (metal-oxide-semiconductor field-effect transistor) by Mohamed Atalla and Dawon Kahng at Bell Labs in 1959 marked a significant advance in the field of power electronics. Power designers were able to achieve performance and density levels with MOSFET transistor generations that were not feasible with bipolar transistors. The power MOSFET was first made accessible in the 1970s as a result of advancements in MOSFET technology, which was initially utilized to create integrated circuits.

 

The first vertical power MOSFET, subsequently known as the VMOS, was introduced by Hitachi in 1969. (V-groove MOSFET). Yamaha, JVC, Pioneer, Sony, and Toshiba all started making audio amplifiers utilizing power MOSFETs in 1974. A 25 A, 400 V power MOSFET was first offered by International Rectifier in 1978. Compared to a bipolar transistor, this device can operate at greater frequencies, however it can only be used in low voltage applications.

 

Due to its low gate drive power, quick switching speed, simple advanced paralleling capability, wide bandwidth, robustness, easy drive, simple biasing, ease of application, and ease of maintenance, the power MOSFET is the most widely used power device in the world. It has a wide range of power electronic applications, including mobile phones, laptop computers, portable information appliances, power integrated circuits, and the network that makes the Internet possible.

 

Insulated-gate bipolar transistors (IGBTs) were first introduced in 1982. In the 1990s, it was readily accessible. This component combines the benefits of the isolated gate drive of the power MOSFET with the power handling capacity of the bipolar transistor.

 

Power electronics

Devices:

The available active devices dictate the capabilities and efficiency of a power electronics system. A crucial component in the design of power electronics systems is their characteristics and constraints. Power electronics previously made extensive use of the mercury arc valve, high-vacuum and gas-filled diode thermionic rectifiers, and triggered devices like the thyratron and ignitron. Vacuum devices have been mostly supplanted with solid-state devices as their ratings in terms of voltage and current-handling capabilities have increased.

 

Power electronic components can be utilized as amplifiers or switches. An ideal switch is either open or closed, dissipating no power; it can either pass no current while being applied with a voltage, or it may flow any current with no voltage drop. The majority of power electronic applications rely on switching devices on and off because semiconductor devices employed as switches may approximate this perfect quality. This results in extremely efficient systems because very little power is lost in the switch. In contrast, the current flowing through an amplifier varies continually in response to a controlled input.The power dissipation inside the device is significant relative to the power given to the load, and the voltage and current at the device terminals follow a load line.

 

How gadgets are used is determined by a number of factors. Devices like diodes start conducting when a forward voltage is provided; there is no external control over this process. Power devices like mercury valves and thyratrons, as well as silicon-controlled rectifiers and thyristors, enable control of the onset of conduction but depend on periodic reversal of current flow to turn them off.Devices that offer full switching control and may be turned on or off regardless of the current flow through them include gate turn-off thyristors, BJTs, and MOSFET transistors. Although proportional amplification is also possible with transistor devices, it is rarely employed for systems with a power rating higher than a few hundred watts. The design of a device is also greatly influenced by its control input characteristics; occasionally, the control input is at a very high voltage relative to ground and needs to be powered by an isolated source.

 

The losses produced by a power electronic device should be as small as feasible because efficiency is crucial in a power electronic converter.

 

Device switching rates vary. Diodes and thyristors can be used for power frequency switching and control at relatively low speeds; certain thyristors work well at a few kilohertz. In power applications, devices like MOSFETS and BJTs can switch at frequencies ranging from tens of kilohertz to a few megahertz, but with diminishing power levels. Applications requiring high power (hundreds of kW) at extremely high frequency (hundreds or thousands of megahertz) are dominated by vacuum tube devices. Faster switching mechanisms reduce the energy lost during the switchovers from on to off and back, but they may cause issues with radiated electromagnetic interference.To obtain the maximum switching speed a device is capable of, gate drive (or comparable) circuits must be built to generate enough drive current. Excessive heating could ruin a device that lacks the drive to switch quickly.

 

Practical devices require some time to travel through an active zone before they reach the "on" or "off" state, have a non-zero voltage drop, and dissipate power when turned on. These losses account for a sizeable portion of the overall power lost in a converter.

 

 

 

Device power handling and dissipation are important design considerations as well. Power electrical equipment may need to dissipate tens or even hundreds of watts of waste heat while switching between conducting and non-conducting states as effectively as feasible.The power controlled in the switching state is significantly greater than the power lost in the switch. Heat must be released as a result of the forward voltage drop in the conducting condition. Exotic semiconductors like silicon carbide have an advantage over straight silicon in this regard, and germanium, once the mainstay of solid-state electronics, is now little used because of its unfavorable high-temperature properties. High power semiconductors need specialized heat sinks or active cooling systems to manage their junction temperature.

 

There are semiconductor devices with single-device ratings of up to a few kilovolts. Multiple devices must be connected in series to regulate very high voltage, and networks must be employed to maintain an even voltage across every device.Once more, switching speed is important since the device with the slowest switching will need to withstand a disproportionate amount of the total voltage. Mercury valves were originally offered with 100 kV ratings in a single unit, making it easier to use them in HVDC systems.

 

Heat created in the dies and heat developed in the resistance of the interconnecting leads limit the current rating of a semiconductor device. The internal junctions (or channels) of semiconductor devices must be equally spread with current; otherwise, breakdown processes can quickly kill the device once a "hot spot" forms. There are certain SCRs that can handle currents of up to 3000 amps in a single unit.

 

Converters for DC/AC (inverters):

DC to AC converters turn a DC source into an AC output waveform. Uninterruptible power supplies (UPS), flexible AC transmission systems (FACTS), voltage compensators, and solar inverters are a few examples of applications. Voltage source inverters and current source inverters are two unique groups of topologies for these converters. The independently regulated output of voltage source inverters, often known as VSIs, is a voltage waveform. The controlled AC output of current source inverters (CSIs) is unique in that it has a current waveform.

Power switching devices, which are frequently completely programmable semiconductor power switches, are responsible for converting DC to AC power. Due to the discrete values used in the output waveforms, quick transitions rather than smooth ones are produced. Even a crude approximation of the sinusoidal waveform of AC power suffices for some purposes. The switching devices are run much faster than the desired output frequency when a nearly sinusoidal waveform is required, and the amount of time they spend in each state is adjusted to provide an output that is nearly sinusoidal on average. The carrier-based technique, often known as pulse-width modulation, the space-vector technique, and the selective-harmonic technique are all common modulation methods.

 

Both single-phase and three-phase applications can effectively use voltage source inverters. Power supplies, single-phase UPSs, and complex high-power topologies when utilized in multicell arrangements are all common uses for single-phase VSIs, which employ half-bridge and full-bridge configurations. Applications requiring sinusoidal voltage waveforms, such ASDs, UPSs, and some FACTS devices like the STATCOM, use three-phase VSIs. Additionally, they are utilized in situations where arbitrary voltages are necessary, such as voltage compensators and active power filters.

 

Current source inverters are employed to convert a DC current source into an AC output current. When three-phase applications need for high-quality voltage waveforms, this kind of inverter can be useful.

 

Multilevel inverters, a comparatively new class of inverters, have drawn a lot of attention. Due to the fact that power switches connect to either the positive or the negative DC bus, CSIs and VSIs operate normally as two-level inverters. The AC output would more closely resemble a sine wave if there were more than two voltage levels available at the inverter output terminals. Because of this, multilevel inverters perform better despite being more complicated and expensive.

 

Different inverter types use different DC connections and have different requirements for freewheeling diodes. Depending on the application, either can be configured to run in square-wave or pulse-width modulation (PWM) mode. Square-wave mode is more straightforward, whereas PWM may be used in a variety of ways and generates waveforms of superior quality.

 

Voltage Source Inverters (VSI) provide a roughly constant voltage source for the output inverter portion.

 

 

 

For a particular application, the appropriate modulation technique is determined by the desired quality of the current output waveform. A VSI's output is made up of discrete values. The loads must be inductive at the chosen harmonic frequencies to provide a smooth current waveform.A capacitive load will result in a choppy current waveform with significant and frequent current spikes if there is no inductive filtering between the source and load.

 

Three basic categories of VSIs exist:

l a half-bridge inverter for one phase.

l full-bridge single-phase inverter

l voltage source inverter for three phases

 

A half-bridge inverter for one phase:

The single-phase voltage source half-bridge inverters are frequently used in power supply and are designed for lower voltage applications.

The inverter's functioning causes low-order current harmonics to be injected back into the source voltage. This indicates that two substantial capacitors are required in this design for filtering, and that only one switch can be activated simultaneously in each leg of the inverter. The DC source would be shorted out if both switches in a leg were on at once.

 

Several modulation methods can be used by inverters to regulate their switching protocols. A carrier voltage signal, v, and an AC output waveform, vc, are compared using the carrier-based PWM approach. S+ is activated when vc exceeds v, and S- is activated when vc is less than v. The PWM transforms into a specific sinusoidal case of the carrier based PWM when the triangle carrier signal is at frequency f with its amplitude at v and the AC output is at frequency fc with its amplitude at vc. The term for this situation is sinusoidal pulse-width modulation (SPWM). The modulation index, also known as the amplitude-modulation ratio.

 

A larger basic AC output voltage will be seen, albeit at the cost of saturation, if the over-modulation region, ma, surpasses one. The output waveform's harmonics for SPWM have well-defined frequencies and amplitudes. This makes it easier to design the filtering parts required for the low-order current harmonic injection resulting from the inverter's operation. In this mode of operation, the maximum output amplitude is equal to half the source voltage. When the maximum output amplitude, ma, is greater than 3.24, the inverter's output waveform changes to a square wave.

 

Both switches in a leg of square wave modulation cannot be switched on simultaneously since doing so would result in a short across the voltage source, as was the case with pulse-width modulation (PWM). S+ and S- must both be on for a half cycle of the AC output period in order for the switching method to function.

 

As a result, the inverter does not control the AC output voltage; rather, the inverter's DC input voltage magnitude does.

 

Selective harmonic elimination (SHE) is a modulation method that enables the inverter to be switched while removing specific inherent harmonics. Additionally, the basic element of the AC output voltage can be changed within a desired range. Even harmonics do not occur since the AC output voltage created using this modulation approach has odd half-wave and odd quarter-wave symmetry.  It is possible to remove any unwelcome odd (N-1) intrinsic harmonics from the output waveform.

 

Full-bridge single-phase inverter:

Similar to the half bridge inverter, the full bridge inverter contains an extra leg that connects the neutral point to the load.

 

S1+ and S1-, as well as S2+ and S2-, cannot be turned on at the same time in order to prevent shorting out the voltage source. When using a modulation method for a full-bridge configuration, only one of the switches on each leg should be active at any given time—either the top switch or the bottom switch. The additional leg causes the output waveform's maximum amplitude, Vi, to be twice as large as the half-bridge configuration's maximum practicable output amplitude.

 

Bipolar SPWM is utilized to produce States 1 and 2 from Table 2 for the AC output voltage. There are only two possible options for the AC output voltage: Vi or -Vi. Using a half-bridge design, a carrier-based method can be employed to obtain the same states. S1+ and S2 are on for the full-bridge when S+ is on for the half-bridge. Similar to how S- is on for the full bridge, S1- and S2+ are on for the half bridge. This modulation method produces an output voltage that is roughly sinusoidal, with a fundamental component whose amplitude in the linear area is less than or equal to one.

 

The unipolar approach generates its AC output voltage using states 1, 2, 3, and 4 from Table 2 as opposed to the bipolar PWM method. Consequently, the AC output voltage can be Vi, 0 or -Vi. As shown in Figure 4, two sinusoidal modulating signals, Vc and -Vc, are required to produce these states.

 

VaN is produced by Vc, whereas VbN is produced by -Vc. The relationship described below is known as unipolar carrier-based SPWM.

 

VaN and VbN's phase voltages are identical but 180 degrees out of phase with one another. There are no even harmonics in the output voltage, which is equal to the difference between the two-phase voltages. As a result, if mf is measured, even the harmonics of the AC output voltage will manifest at normalized odd frequencies, fh. The center of these frequencies is two times the normalized carrier frequency. When attempting to produce an output waveform of higher quality, this particular feature enables smaller filtering components.

 

Due to its odd half-wave and odd quarter-wave symmetry, the AC output voltage does not contain any even harmonics, as was the case for the half-bridge SHE.

 

 

 

 

Voltage source inverter for three phases:

While three-phase VSIs span both the medium and high power ranges, single-phase VSIs are typically employed for low power applications.

 

This prevents switches from being turned off simultaneously in any of the three legs of the inverter, which causes the voltages in each leg to rely on the polarity of the corresponding line current. Zero AC line voltages are produced by states 7 and 8, which cause AC line currents to freely flow through either the upper or lower components. The line voltages for states 1 through 6, however, result in an AC line voltage that is made up of the discrete values Vi, 0 or -Vi.

 

In order to create out-of-phase load voltages for three-phase SPWM, three modulating signals that are 120 degrees out of phase with one another are used. The normalized carrier frequency, mf, must be a power of three greater than the single carrier signal in order to maintain the PWM features. As a result, the phase voltages remain the same size but remain 120 degrees out of phase with one another. The linear region's highest phase voltage amplitude, ma less than or equal to one.

 

Changing the input DC voltage is the sole technique to regulate the load voltage.

 

Semiconductor device:

Introduction:

A semiconductor device is an electronic component that operates primarily on the electronic properties of silicon, germanium, gallium arsenide, as well as organic semiconductors. Its conductivity falls in the range of insulators and conductors. Vacuum tubes have mostly been supplanted by semiconductor devices. Instead of conducting electricity as free electrons through a vacuum (usually released by thermionic emission) or as free electrons and ions via an ionized gas, they do so in the solid state.

 

Semiconductor device

Both discrete single semiconductor devices and integrated circuit (IC) chips—which contain two or more devices that can range in number from the hundreds to the billions—are produced in the semiconductor industry (also called a substrate).

 

Semiconductor materials are advantageous because doping, or the intentional addition of impurities, can quickly change their behavior. Semiconductors make great sensors because they have the ability to control conductivity through the application of an electric or magnetic field, exposure to light or heat, or mechanical deformation of a doped monocrystalline silicon grid. Charge carriers, also referred to as mobile or "free" electrons and electron holes, are responsible for current conduction in semiconductors. The amount of free electrons or holes within a semiconductor is significantly increased by doping it with a little amount of an atomic impurity, such as boron or phosphorus.A doped semiconductor is referred to as a p-type semiconductor (p for positive electric charge) when it has an excess of holes, and an n-type semiconductor when it has an excess of free electrons (n for negative electric charge). Most mobile charge providers use a negative charge. The placement and concentration of p- and n-type dopants are precisely controlled during semiconductor fabrication. P-n junctions are created when n- and p-type semiconductors are connected.

 

The metal-oxide semiconductor field-effect transistor, also known as the MOS transistor, is the most popular semiconductor device in use today. As of 2013, every day billions of MOS transistors are produced. Since 1978, the number of semiconductor devices produced annually has increased by 9.1% on average. In 2018, shipments are expected to reach 1 trillion for the first time, suggesting that well over 7 trillion semiconductor devices have been produced overall.

 

Common semiconductor devices are listed as:

n DIAC

n Diode (rectifier diode)

n Gunn diode

n IMPATT diode

n Laser diode

n Light-emitting diode (LED)

n Photocell

n Phototransistor

n PIN diode

n Schottky diode

n Solar cell

n Transient-voltage-suppression diode

n Tunnel diode

n VCSEL

n Zener diode

n Zen diode

n Bipolar transistor

n Darlington transistor

n Field-effect transistor

n Insulated-gate bipolar transistor (IGBT)

n Silicon-controlled rectifier

n Thyristor

n TRIAC

n Unijunction transistor

n Hall effect detector (magnetic field sensor)

n Photocoupler (Optocoupler)

 

Semiconductor device

Applications for Semiconductor Devices:

The building blocks of logic gates, which are essential in the creation of digital circuits, can be any form of transistor. Transistors serve as on-off switches in digital circuits like microprocessors; in the case of a MOSFET, for example, the voltage provided to the gate decides whether the switch is on or off.

 

Instead of functioning as on-off switches, analog circuit transistors respond to a continuous range of inputs with a continuous range of outputs. Amplifiers and oscillators are examples of typical analog circuits.

 

Mixed-signal circuits are those that interface or translate between digital and analog circuitry.

 

Semiconductor device

Identifiers for components:

 

Devices made of semiconductors frequently have manufacturer-specific component numbers. However, some devices adhere to the type code standards that have been attempted to be created. There are three standards, for instance, for discrete devices: Pro Electron in Europe, JEDEC JESD370B in the United States, and Japanese Industrial Standards (JIS).

 

Discrete or integrated circuits designed for high current or high voltage applications are known as power semiconductor devices. Power integrated circuits, sometimes known as "smart" power devices, combine power semiconductor technology with IC technology. Power semiconductor production is a niche industry with several manufacturers.