REVIEWER-IN-ELECTRONICS-3.docx

**REVIEWER IN ELECTRONICS 3** **What are power electronics?** - Is the application of electronics to control and conversion of electric power - Power electronics is regarded as an important subfield of electrical and electronics engineering **Concept of power electronics** The branc...

**REVIEWER IN ELECTRONICS 3** **What are power electronics?** - Is the application of electronics to control and conversion of electric power - Power electronics is regarded as an important subfield of electrical and electronics engineering **Concept of power electronics** The branch of electrical engineering is sub-classified into three categories namely: - Electronics , power and control - Electronics generally revolves around semiconductor devices and circuits and thus the arrival of various technologies has made electronics a crucial branch of engineering.  **POWER SEMICONDUCTOR DEVICES** - A power semiconductor device is a semiconductor device used as a switch or rectifier in power electronics. - Called a power device - Used in commutation mode **Classification of solid-state devices** - Two terminal device a. Diode - Three -- terminal device A. Silicon controlled rectifier (SCR) B. Thyristor C. Gate turn off thyristor D. Triac E. Bipolar Junction Transistor F. Power Mosfet - **Four Terminal Device** A. **IGBT** B. **MCT** C. **IGCT** **Power Semiconductor Devices** **Silicon-controlled rectifier (SCR)** \- This semi-controlled device turns on when a gate pulse is present and the anode is positive compared to the cathode. \- is a four-layer solid-state current-controlling device. The name \"silicon controlled rectifier\" is General Electric\'s trade name for a type of thyristor **3 states of thyristors** - **Forward conducting -** This is a thyristor\'s primary operating mode. It is switched to conducting mode and stays that way until the current falls below a specific level, called the *holding current*. - **Forward blocking -** The thyristor blocks the flow of current, despite voltage being applied in the direction that would signal a Diode to conduct it. - **Reverse blocking mode -** Current attempts to pass through the thyristor in the opposite direction. However, a diode blocks it, and the thyristor is not activated. **Triggering/Firing -** This method of securing SCR conduction is called triggering or firing, and it is by far the most common way that SCRs are latched in actual practice. **Reverse Triggering -** A variation of the SCR, called a Gate-Turn-Off thyristor, or GTO. **SCRs vs GTOs** A **thyristor** is a [solid-state](https://en.wikipedia.org/wiki/Solid_state_(electronics)) a solid-state [semiconductor](https://en.wikipedia.org/wiki/Semiconductor_device) a solid-state semiconductor device with four layers of alternating P- and [N-type](https://en.wikipedia.org/wiki/N-type_semiconductor) - FORWARD CONDUCTING - FORWARD BLOCKING - REVERSE BLOCKING MODE A **power MOSFET** is a specific type of metal oxide semiconductor field-effect transistor ([MOSFET](https://en.wikipedia.org/wiki/MOSFET)) designed to handle significant power levels. An **insulated-gate bipolar transistor** (**IGBT**) is a three-terminal [power semiconductor device](https://en.wikipedia.org/wiki/Power_semiconductor_device)) is a three-terminal power semiconductor device primarily used as an electronic switch which, as it was developed, came to combine high efficiency and fast switching. An **MOS-controlled thyristor (MCT)** is a voltage-controlled fully controllable [thyristor](https://en.wikipedia.org/wiki/Thyristor). It was invented by V.A.K. Temple. **Advantages of Power Electronics Converters** - Highly reliable - Less loss of power - Efficient - Fast response - Long life - Small size and less in weight **Disadvantages of Power Electronics Converters** - Low overload capacity - Harmonics are generated - Expensive **Applications of Power Electronics** - **Industries** - **Home appliances** - **Commercial** - **Medical** - **Automotive and Security Systems** - **Aerospace** - **Transportation** - **Telecommunications** - **Power Systems** **Lesson 1.b** **Bidirectional Thyristor devices** - Silicon controlled thyristor or SCRs - Gate turn off thyristors or GTOs - Emitter turn off thyristors or ETOs - Reverse conducting thyristors or RCTs - Bidirectional Triode Thyristors or TRIACs - MOS turn off thyristors or MTOs - Bidirectional phase controlled thyristors or BCTs - Fast switching thyristors or SCRs - Light activated silicon controlled rectifiers or LASCRs - FET controlled thyristors or FET-CTHs - Integrated gate commutated Thyristors or IGCTs **What is a Bidirectional Thyristor?** A bidirectional control thyristor (BCT) consists of two thyristors integrated on the same silicon wafer with separate gate contacts. **What is a DIAC?** - A DIAC is a full-wave or bi-directional semiconductor switch that can be turned on in both forward and reverse polarities. - The name DIAC comes from the words **[DI]**ode **[AC]** switch. **Advantages** - The DIAC can be turned on and off by reducing the voltage below its avalanche voltage. - It is easily available at low cost. - It has very small size. **Disadvantages** - It works above a specific voltage. - Low power handling capacity. - It cannot protect circuits from high voltage. **What is the difference between a DIAC and a TRIAC ?** 1. Both DIAC and TRIAC are from thyristor family. 2. A DIAC is a two terminal device whereas a TRIAC is a three terminal device. 3. A DIAC is generally connected to base pin of TRIAC that triggers it ON / OFF. **What is a TRIAC?** -  TRIAC is a bidirectional, three-electrode AC switch that allows electrons to flow in either direction. - A TRIAC is triggered into conduction in both directions by a gate signal like that of an SCR. TRIACs were designed to provide a means for the development of improved AC power controls. **LESSON 2** **Optoelectronic Devices** Optocouplers or opto isolators consisting of a combination of an infrared [LED] (also IRED or ILED) and an infrared sensitive device such as a photo [diode] or a photo transistor. **Divisions of the electromagnetic spectrum**  **Optical Spectrum: ** extend beyond what the eye can detect and include wavelengths between about *1 nm and 105 nm* which interact with materials in similar ways. **Wave-Photon Duality:** Light is unusual in that it readily displays both wave-like and quantum behavior. Ep = hf = hc/ λ where h is Planck's constant **Interaction with Semiconductors ** - Absorption -- loss due to energy conversion as light passes through a material. - Emission -- Conversion of energy into light. **Analysis of Optical Phenomena ** - **Ray Optics** - a geometric representation of the behavior of light - **Electromagnetic (EM) Optics** - or physical optics, an electromagnetic representation of the behavior of light using Maxwell's equations - **Quantum Optics** - the most general representation of the behavior of light in terms of photons **Semiconductor Optical Devices** - **Photodetectors** 1. Photodiodes 2. Phototransistor - **Semiconductor Light Sources** 1. Light emitting Diodes 2. LASER DIODE **Semiconductor structures -** Incident photons are converted by semiconductor structures into usable electrons. **Optocouplers** or **opto isolators** consisting of a combination of an infrared LED (also IRED or ILED) and an infra red sensitive device such as a photodiode or a phototransistor. - Communication within an optocoupler occurs when an applied CMOS logic input generates an input-side current, which then creates a proportional LED output for transmission through the molding compound barrier to the receiving photodetector and output. **Types of Optocouplers** - AC input Phototransistor - Photo Darlington output optocoupler - Bi-Directional linear output optocoupler - PhotoSCR output optosoupler - PhotoTRIAC output optocoupler - Schmitt-Trigger output optocoupler **Application Circuits** - Input Current control - AC Optocoupler - Analog or Digital Conversion - Optocoupler Digital interfacing - Interfacing TTL with Optocoupler - Interfacing CMOS with Optocoupler - Interfacing Arduino Microcontroller and BJT with Optocoupler - Interfacing Analog signal with Optocoupler - Interfacing TRIAC with Optocoupler Credits: bubby pookie wookie mwa mwa! thank you for printing, call me when it's 10:30 na, love you!