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power electronics(ii)
The document discusses various types of rectifier circuits including uncontrolled and controlled single phase and three phase rectifiers. It also discusses different power electronic converters such as inverters, choppers, and cycloconverters. Key devices for power electronics applications discussed include transistors, MOSFETs, IGBTs, and thyristors. Application areas mentioned include UPS, HVDC transmission, and motor drives. The document provides circuit diagrams, operating principles, and example calculations for different power electronic converters.
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power electronics(ii)
- 1. Uncontrolled & controlled Rectifiers Engr.Jahangeer badar soomro
- 3. CLASSIFICATION OF RECTIFIER CIRCUITS 1.Single Phase Half Wave Uncontrolled Rectifier 2. Single Phase Full Wave Uncontrolled Rectifier 3. Three Phase Full Wave Uncontrolled Rectifier 4. Single Phase Half Wave Controlled Rectifier 5. Single Phase Full Wave Controlled Rectifier 6. Three Phase Full Wave Controlled Rectifier.
- 4. Single Phase HalfWave Uncontrolled Rectifier
- 5. Single Phase FullWave Uncontrolled Rectifier using center tap
- 6. Single Phase FullWave Uncontrolled Rectifier using Bridge
- 17. Important Question • Explainthe operation of single phase half wave converter with RL load with the help of circuit diagrams and waveforms. Also discuss that why flywheel diode is connected in such type of circuits. • https://www.youtube.com/watch?v=F57tKwX 63M0
- 23. Also discuss thatwhy flywheel diode is connected in such type of circuits
- 31. Single Phase FullWave Controlled Rectifier Using Center tap/Two Pulse Converter/Mid point Converter
- 38. Single Phase FullWave Controlled Rectifier Using Bridge
- 42. Single Phase FullWave Controlled Rectifier Using Bridge • You guys now know very well about this circuit that how it will operate. • This is our today lab. • Design this circuit in MATLAB. And show the satisfactory results.
- 43. Three Phase FullWave Uncontrolled Rectifier • https://www.youtube.com/watch?v=Ij9aCSC8 QBY • It is your assignment to cover three phase uncontrolled rectifier from this video. • Very easily explained and informative. • You must listen this video.
- 44. Three Phase FullWave controlled Rectifier • https://www.youtube.com/watch?v=Ij9aCSC8 QBY • It is your assignment to cover three phase controlled rectifier from this video. • Very easily explained and informative. • You must listen this video.
- 45.
- 55. DC TO DCCONVERTER OR CHOPPER ENGR. JAHANGEER BADAR SOOMRO
- 59. Efficiency & PowerLosses • Efficiency is a good measure of the success of a given converter technology. • With very small amount of power lost, the converter elements can be packaged with high density, leading to a converter of small size and weight, and of low temperature rise. • How can we build a circuit that changes the voltage, yet dissipates negligible power?
- 76. Linear Regulators VsSwitch Mode Conversion Converter • Linear Regulators are inefficient • Linear Regulators have a high drop out voltage. • They are limited to output voltage smaller than input voltage . • Linear regulators can however provide a very high quality output voltage but they are used for application of low power level as low drop-out-voltage voltage regulators. • At higher power levels switching regulators are used. • Switched mode conversion offers you high efficiency as discussed in class. (Due to switching phenomenon)
- 81. Linear Regulators VsSwitch Mode Conversion Converter • A 7 minute video comparing beautifully linear regulator vs switch mode conversion converter. • https://www.youtube.com/watch?v=giGRrOD KJSE
- 82. Principle of StepDown Chopper
- 86. Design procedure forBuck Converter • Calculate D to obtain required output voltage. • Select a particular switching frequency: – –preferably >20KHz for negligible acoustic noise • Higher fs results in smaller L, but higher device losses. – Thus lowering efficiency and larger heat sink.
- 87. Design procedure forBuck Converter • Inductor requirement • C Calculation • Possible switching devices: MOSFET, IGBT and BJT. Low power MOSFET can reach MHz range. 𝑟 = 1 − 𝐷 8𝐿𝐶𝑓2 𝐿 ≥ 𝐿 𝑚𝑖𝑛 = 1 − 𝐷 2𝑓 𝑅
- 90. Example-2 • A buckconverter has an input voltage of 50V and output of 25V. The switching frequency is 10KHz. The power output is 125W. (a) Determine the duty ratio, (b) value of L to ensure continuous current, (c) value of capacitance to limit the output voltage ripple factor to 0.5%. 90 Solution (a) output voltage 𝑉𝑜 = 𝐷𝑉𝑠 (b) Value of L 𝐷 = 𝑉𝑜 𝑉𝑠 𝐷 = 25 50 = 0.5 𝐿 ≥ 𝐿 𝑚𝑖𝑛 = 1 − 𝐷 2𝑓 𝑅 𝐿 ≥ 𝐿 𝑚𝑖𝑛 = 1 − 0.5 2 × 10𝐾 𝑅 𝑃𝑜 = 𝑉2 𝑅
- 91. Example-2 • Resistance iscalculated as • L must at least be 10 times greater than Lmin. 91 𝑅 = 𝑉2 𝑃𝑜 = 252 125 = 5Ω 𝐿 ≥ 𝐿 𝑚𝑖𝑛 = 1 − 0.5 2 × 10𝐾 × 5 𝐿 ≥ 𝐿 𝑚𝑖𝑛 = 2.5 20𝐾 = 125𝜇𝐻 𝐿 = 1.25𝑚𝐻
- 92. Example-2 • Value ofcapacitance to limit the output voltage ripple factor to 0.5% can be calculated using following equation. 92 (c) Value of C 𝑟 = 1 − 𝐷 8𝐿𝐶𝑓2 0.005 = 1 − 0.5 8 × 1.25𝑚 × 𝐶 × (10𝐾)2 𝐶 = 1 − 0.5 8 × 1.25𝑚 × 0.005 × (10𝐾)2 𝐶 = 0.5 5000 = 100𝜇𝐹
- 114. Step-Up Converter (BoostConverter) • Boost Converter Design • Minimum inductor value • Capacitor Value 𝐿 𝑚𝑖𝑛 = 𝐷(1 − 𝐷)2 𝑅 2𝑓 𝑟 = 𝐷 𝑅𝐶𝑓
- 116. http://www.learnabout- electronics.org/PSU/psu33.php Buck-Boost Converter Please referto following link for excellent material on buck-boost.
- 117. Concept Of Commutation Engr.Jahangeer Badar Soomeo
- 123. Power Converters Engr. JahangeerBadar Soomro
- 128. One particular reasonwhy you need Power Electronics is that you do not have DC transformers and AC batteries.
- 134. DC TO ACCONVERTER OR IINVERTER ENGR.JAHANGEER BADAR
- 135.
- 137. • Thyristor basedinverters are used for high power applications. • For low and medium power inverters fully controlled devices such as Power BJT and Power Mosfet, IGBT, GTO, SIT are used. In addition to having fully controlled these devices high switching frequencies. • Therefore these devices may be employed very efficiently in inverters where the output voltage is controlled using PWM techniques.
- 146. TYPICAL APPLICATIONS – Un-interruptiblepower supply (UPS) 146
- 147. TYPICAL APPLICATIONS – HVDC(High Voltage Direct Current) 147
- 148. Types of Inverters •There are three basic types of dc-ac converters depending on their AC output waveform: – Square wave Inverters – Modified sine wave Inverters – Pure sine wave Inverters 148
- 149. Square Wave Inverters –The square wave is the simplest and cheapest type, but nowadays it is practically not used commercially because of low power quality (THD≈45%). 149
- 150. Modified Sine waveInverters • The modified sine wave topologies provide rectangular pulses with some dead spots between positive and negative half-cycles. • They are suitable for most electronic loads, although their THD is almost 24%. • They are the most popular low-cost inverters on the consumer market today, 150
- 151. Pure Sine WaveInverters – A true sine wave inverter produces output with the lowest total harmonic distortion (normally below 3%). – It is the most expensive type of AC source, which is used when there is a need for a sinusoidal output for certain devices, such as medical equipment, laser printers, stereos, etc. – This type is also used in grid-connected applications. 151
- 152. Simple square-wave inverter •To illustrate the concept of AC waveform generation
- 153.
- 154.
- 155. Output voltage harmonics •Harmonics may cause degradation of equipment (Equipment need to be “de-rated”). • Total Harmonic Distortion (THD) is a measure to determine the “quality” of a given waveform. 155 𝑇𝐻𝐷𝑣 = 𝑛=2 ∞ 𝑉𝑛,𝑅𝑀𝑆 2 𝑉1,𝑅𝑀𝑆 𝑇𝐻𝐷𝑖 = 𝑛=2 ∞ 𝐼 𝑛,𝑅𝑀𝑆 2 𝐼1,𝑅𝑀𝑆
- 156. Fourier Series • Studyof harmonics requires understanding of wave shapes. • Fourier Series is a tool to analyse wave shapes. • Where, 156 𝑣 𝑡 = 𝑎 𝑜 + 𝑛=1 ∞ 𝑎 𝑛 cos 𝑛𝜃 + 𝑏 𝑛 sin 𝑛𝜃 𝑎 𝑛 = 1 𝜋 0 2𝜋 𝑣 𝑡 cos 𝑛𝜃 𝑑𝜃 𝑏 𝑛 = 1 𝜋 0 2𝜋 𝑣 𝑡 sin 𝑛𝜃 𝑑𝜃 𝑎 𝑜 = 1 𝜋 0 2𝜋 𝑣 𝑡 𝑑𝜃
- 157. Filtering • Low-pass filteris normally fitted at the inverter output to reduce the high frequency harmonics. 157
- 158. 1-∅ Voltage sourceInverters • Single phase voltage source inverters are of two types. – Single Phase Half Bridge voltage source inverters – Single Phase full Bridge voltage source inverters 158
- 162.
- 181. Power Transistors &Power MOSFETS Engr. Jahangeer Badar Soomro
- 183. INSULATED GATE BIPOLAR TRANSISTOR(IGBT) IGBT is a voltage controlled device. It has high input impedance like a MOSFET and low on-state conduction losses like a BJT. Figure below shows the basic silicon cross-section of an IGBT. Its construction is same as power MOSFET except that n+ layer at the drain in a power MOSFET is replaced by P+ substrate called collector. n epi n Bufferlayer p p n n Gate Gate Emitter Collector G E C
- 207.