power electronics*

power electronics

power electronics*TEXT BOOKS

Power Electronics by M. D. Singh & K. B. Kanchandhani, Tata Mc Graw Hill Publishing company, 1998.

Power Electronics : Circuits, Devices and Applications by M. H. Rashid, Prentice Hall of India, 2nd edition

power electronics

power electronics*REFERENCE BOOKS Power Electronics - by V.R.Moorthy , 1st edition -2005, OXFORD University Press

Power Electronics by Vedam Subramanyam, New Age International (P) Limited, Publishers

Power Electronics-by P.C.Sen,Tata Mc Graw-Hill Publishing

power electronics

power electronics*UNIT-1POWER SEMI CONDUCTOR DEVICES

power electronics

power electronics*Introduction to Power Electronics Lecture-1

power electronics

power electronics*

power electronics

power electronics*

power electronics

power electronics*

power electronics

power electronics*

power electronics

power electronics*

power electronics

power electronics*

power electronics

power electronics*Power Electronics*History of Power ElectronicsMercury arc rectifier (year 1900).Metal tank rectifier.Grid controlled vacuum tube rectifier.Ignitron, Phanatron, ThyratronSCR (Silicon Controlled Rectifier) - The 1st Thyristor developed by Bell labs in 1956. 1st Commercial grade SCR developed by General Electric Co. in 1958.

power electronics

power electronics*Power Electronics*Power Electronic ApplicationsCommercial ApplicationsAir conditionersCentral refrigeration.UPSElevatorsEmergency lampsHeating systemsDomestic ApplicationsCooking equipments.Lighting & heating ckts.Air conditioners.Refrigerators.Freezers.Personal Computers.

power electronics

power electronics*Power Electronic ApplicationsTelecommunicationsBattery chargers.DC power supply & UPSMobile cell phone battery chargers.TransportationTraction control of electric vehicles.Battery chargers for electric vehicles.Electric locomotives.Street cars & trolley buses.

power electronics

power electronics*Power Electronics*Power Electronic ApplicationsUtility SystemsHigh voltage DC transmissions (HVDC).Static VAR compensation.Fuel cells.Energy storage systemsBoiler feed water systems.

power electronics

power electronics*Power Electronics*Power DevicesPower DiodePower BJTPower MOSFETIGBTThyristor (SCR)

power electronics

power electronics*Power Electronics

Applications of Power Devices*

power electronics

power electronics*Power Electronics*Thyristorised Power Converter

power electronics

power electronics*Power Electronics*AdvantagesEasy and flexibility in operation due to digital controls.Faster dynamic response compared to the electro mechanical converters.Lower acoustic noise when compared to electro magnetic controllers, relays and contactors.

power electronics

power electronics*Power Electronics*ContdHigh efficiency due to low losses in the Thyristors.Long life and reduced/minimal maintenance due to the absence of mechanical wear.Control equipments using Thyristors are compact in size.

power electronics

power electronics*Power Electronics*DisadvantagesGenerate unwanted harmonics.Harmonics are injected into power supply lines affecting the performance of other loads and equipments.Unwanted interference with communication circuits due to electromagnetic radiation.

power electronics

power electronics*Power Electronics*Special protection circuits must be used to protect the thyristor devices.

Thyristors must be rated for maximum loading conditions.

Special steps are to be taken for correcting line supply power factor.

power electronics

power electronics*Power Electronics*Different types of Power ConvertersDiode rectifiers (uncontrolled rectifiers).Line commutated converters or AC to DC converters (controlled rectifiers).AC voltage (RMS voltage) controllers (AC to AC converters).

power electronics

power electronics*Power Electronics*Cyclo converters (AC to AC converters at low output frequency).

DC choppers (DC to DC converters).

Inverters (DC to AC converters).

power electronics

power electronics*Power Electronics*AC to DC Converter

Type of input: AC supply (fixed voltage & frequency)Type of output: DC voltage (variable)

power electronics

power electronics*Power Electronics*AC to DC Converter

power electronics

power electronics*Power Electronics*

power electronics

power electronics*

Application Of Power Electronics

power electronics

power electronics*Power Electronics*Speed control of DC motor in DC drives.UPS.HVDC transmission.Battery Chargers.Application Of Power Electronics

power electronics

power electronics*Power Electronics*AC Voltage Regulators

Type of input: AC supply (fixed voltage & frequency).Type of output: Variable AC RMS O/P voltage.

power electronics

power electronics*Power Electronics*

power electronics

power electronics*Power Electronics*ApplicationsSpeed control of ac motors.Speed control of fans (domestic and industrial fans).AC pumps.

power electronics

power electronics*Power Electronics*Cyclo Converters

Type of input: AC supply (fixed voltage & frequency).Type of output: Variable frequency ac O/P voltage.

power electronics

power electronics*Power Electronics*Applications Traction vehicles Gearless rotary kilns.

power electronics

power electronics*Power Electronics*DC Choppers

Type of input: Fixed DC supply voltage.Type of output: Variable DC voltage.

power electronics

power electronics*Power Electronics*

power electronics

power electronics*Power Electronics*ApplicationsSpeed control of DC motors from a DC supply.DC drives for sub-urban traction.Switching power supplies.

power electronics

power electronics*Power Electronics*Inverters

Type of input: Fixed DC supply voltage.Type of output: AC O/P voltage.

power electronics

power electronics*Power Electronics*

power electronics

power electronics*Power Electronics*Applications Industrial AC drives using induction and synchronous motors.Uninterrupted power supplies (UPS system) used for computers, computer labs.

power electronics

power electronics*Power Electronics*Peripheral Effects

power electronics

power electronics**ContdInduced current and voltage harmonic into supply system, and at the output of the converters.Distortion in the output voltage.Unwanted electromagnetic radiation.Interference with communication circuits.

power electronics

power electronics*

Basic theory of operation of SCR Static characteristics

power electronics

power electronics*

power electronics

power electronics*

power electronics

power electronics*

power electronics

power electronics*Modes of operation of ThyristorReverse Blocking mode

Forward Blocking mode

Forward Conduction Mode

power electronics

power electronics*

power electronics

power electronics* HOLDING CURRENT

After an SCR has been switched to the on state a certain minimum value of anode current is required to maintain the thyristor in this low impedance state. If the anode current is reduced below the critical holding current value, the thyristor cannot maintain the current through it and reverts to its off state usually is associated with turn off the device.

power electronics

power electronics*ContdThus holding current may be defined as the minimum value of anode current below which it must fall for turning off the thyristor.

power electronics

power electronics*

LATCHING CURRENT

After the SCR has switched on, there is a minimum current required to sustain conduction. This current is called the latching current and it is associated with turn on and is usually greater than holding current.

Latching current is defined as the minimum value of anode current which it must attain during turn-on process to maintain conduction when get signal is removed

power electronics

power electronics*

power electronics

power electronics* Turn-on and turn-off methods

power electronics

power electronics*

power electronics

power electronics*Thermal Turn onIf the temperature of the thyristor is high, there will be an increase in charge carriers which would increase the leakage current. This would cause an increase in current flow & and the thyristor may turn on. This type of turn on may cause thermal run away and is usually avoided.

power electronics

power electronics*Light Turn If light be allowed to fall on the junctions of a thyristor, charge carrier concentration would increase which may turn on the SCR.LASCR Light activated SCRs are turned on by allowing light to strike the silicon wafer.

power electronics

power electronics*High Voltage TriggeringThis is triggering without application of gate voltage with only application of a large voltage across the anode-cathode such that it is greater than the forward breakdown voltage. This type of turn on is destructive and should be avoided.

power electronics

power electronics*TriggeringUnder transient conditions, the capacitances of the p-n junction will influence the characteristics of a thyristor. If the thyristor is in the blocking state, a rapidly rising voltage applied across the device would cause a high current to flow through the device resulting in turn-on.

power electronics

power electronics*If is the current through the junction and is the junction capacitance and is the voltage across , then

power electronics

power electronics*From the above equation, we see that if is large, will be large. A high value of charging current may damage the thyristor and the device must be protected against high . The manufacturers specify the allowable .

power electronics

power electronics*Dynamic characteristics of SCR And Characteristics Of BJT

power electronics

power electronics*

power electronics

power electronics*

power electronics

power electronics*

Characteristics Of BJT

power electronics

power electronics*

power electronics

power electronics*Steady state Characterictics

power electronics

power electronics*INPUT CHARACTERISTICS

power electronics

power electronics*OUTPUT CHARACTERICTICS

power electronics

power electronics*ADVANTAGES OF BJT

power electronics

power electronics*ADVANTAGES OF BJT

power electronics

power electronics*Power MOSFET and its characteristics

power electronics

power electronics*Power MOSFETPower MOSFET is a metal oxide semiconductor field effect transistor. It is a voltage controlled device requiring a small input gate voltage. It has high input impedance. MOSFET is operated in two states viz., ON STATE and OFF STATE. Switching speed of MOSFET is very high. Switching time is of the order of nanoseconds.

power electronics

power electronics*Types of MOSFETMOSFETs are of two types (a) Depletion MOSFETs (b) Enhancement MOSFETs.

MOSFET is a three terminal device. The three terminals are gate (G), drain (D) and source (S

power electronics

power electronics*DEPLETION MOSFET

Fig. : n-channel depletion type MOSFETSymboL

power electronics

power electronics*P-channel Depletion Type MOSFETFig. : P-channel depletion type MOSFETSymbol

power electronics

power electronics*CHARACTERISTICS OF n-Channel Depletion MOSFETFig: n-channel Depletion MOSFET

power electronics

power electronics*Drain Characteristic

power electronics

power electronics*Transfer characteristic

power electronics

power electronics*Characteristics Of n-channel enhancement MOSFETFig: n-channel Enhancement MOSFET

power electronics

power electronics*Transfer CharacteristicGate Source Threshold VoltageFig.: Transfer Characteristic

power electronics

power electronics*Drain Characteristic

Fig. : Drain Characteristic

power electronics

power electronics*Lecture-7IGBT and its characteristics

power electronics

power electronics*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

power electronics

power electronics*Structure And Symbol of IGBT Fig (a) Structure Fig (b) Symbol

power electronics

power electronics*Characteristic of IGBT Fig.: Circuit Diagram to Obtain Characteristics

power electronics

power electronics*Output Characteristics

power electronics

power electronics*Transfer Characteristic

power electronics

power electronics*Lecture-8Characteristics Of Other Devices

power electronics

power electronics*Power Electronics*Power Semiconductor Devices, their Symbols & Characteristics

power electronics

power electronics*Contd

power electronics

power electronics*Power Electronics*DEVICE SYMBOLS & CHARACTERISTICS

power electronics

power electronics*Power Electronics*

power electronics

*Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics**Power Electronics*