PE & S Lab Manual(Student Copy)

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Transcript of PE & S Lab Manual(Student Copy)

Power Electronics & Simulation Lab INDEX

Add-on Experiments Sl.No. 1 2 3 4 5 6 7 8 9 1- AC voltage controller using RLE loads 10 PSPICE Simulation of Resonant pulse commutation circuit and Buck chopper EXPERIMENT NAME 1- Dual converter with R & RL loads. PSPICE Simulation of single phase Inverter with PWM control Forced commutation circuits of SCR 1- Cyclo converter with R & RL loads 41 EXPERIMENT NAME Characteristics of SCR, BJT and MOSFET GATE firing circuits of SCR 1- AC voltage controller with R & RL loads 1- Fully controlled bridge Converter with R & RL loads DC JONES chopper 1- Parallel inverter with R & RL loads 1- Half-controlled Converter with R & RL loads 1- Series inverter with R & RL loads PSPICE Simulation of 1- Full converter using RLE loads and 35 Page No. 2 11 15 18 22 25 28 32

Sl.No. 11 12 13 14

Page No. 48 52 56 66

EEE Department, SVEC, Tadepalligudem

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Power Electronics & Simulation Lab

1. CHARACTERISTICS OF SCR , BJT and MOSFET(a) STATIC CHARACTERISTICS OF SCR AIM : To plot the characteristics of SCR and to find the forward resistance holding current and latching current. APPARATUS : 1) 2) 3) 4) CHARACTERISTICS STUDY UNIT 0-50V DC voltmeter 0-500mA DC ammeter 0-25mA DC Ammeter

CIRCUIT DIAGRAM:

PROCEDURE : 1) Make the connections as per the circuit diagram 2) Now switch on the supply and initially keep v1 and v2 at minimum 3) Set load potentiometer R1 in the minimum position.

EEE Department, SVEC, Tadepalligudem

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Power Electronics & Simulation Lab4) Adjust Ig1 to some value say 10mA by varying V 2 or gate current potentiometer

R2 vary V1 and note down VAK and IA READINGS. 5) Further vary V1 till SCR conducts, this can be noted by sudden drop of V AK and IA readings. 6) Draw the graph VAK vs IA . 7) Repeat the same procedure for different gate currents. MODEL GRAPH:

TO FIND LATCHING CURRENT AND HOLDING CURRENT :1) Apply about 20V between anode and cathode by varying V1. 2) Keep the load potentiometer R1 in minimum position.

3) The device must be in the OFF state with gate open. 4) Gradually increase gate voltage V2 till the device turns ON. This is the minimum gate current required to turn ON the device. 5) Adjust the gate voltage to a slightly higher value and set the load potentiometer at the maximum resistance position, the device should come to OFF state. 6) The gate voltage should be kept constant in this experiment. 7) By varying R1, gradually increase anode current IA in steps. 8) Open and close the gate voltage V2 switch after each switch. 9) If the anode current is greater than the latching current of device, the device stays ON even after the gate switch is opened otherwise the device goes in to blocking mode as soon as the gate switch is opened. 10) Note down the latching current.EEE Department, SVEC, Tadepalligudem Page 3

Power Electronics & Simulation Lab11)Increase the anode current from the latching current level by load pot R1 or V1. 12)Open the gate switch permanently, the thyristors must be carefully ON. 13)Now start reducing the anode current gradually by adjusting R1. 14)If the thyristor does not turns OFF even after the R1 at maximum position then reduce

V1. 15) Observe when the device goes to blocking mode. 16) The anode current at this instant is holding current of the devices. 17)Repeat the steps again to get the holding current IH. TABULAR FORM : S.NO. VBO1= , IG1= VAK (V) IA (A) VBO2= , IG2= VAK (V) IA (A)

RESULT :

EEE Department, SVEC, Tadepalligudem

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Power Electronics & Simulation Lab

(b) CHARACTERISTICS OF IGBT AIM : To plot the input and transfer characteristics of an IGBT to find ON state resistance and the transfer conductance. APPARATUS : 1) IGBT 1RG BC 20S 2) Resistors 10K/25w, 75/25W 3) DC voltmeter 0-50V 4) DC voltmeter 0-15V 5) DC ammeter 0-500mA THEORY : It is a new development in the area of power MOSFET technology. This device combines in to advantages of both MOSFET and BJT. So an IGBT has high input impedance like as MOSFET and low ON state power like BJT. Further IGBT is free from second breakdown problem present in BJT. IGBT is also known as metal oxide insulated gate transistor. It was also called as insulated gate transistor. The static characteristics or output characteristics of IGBT shows plot of collector current IC vs collector emitter voltage VCE for various values of gate emitter voltage. In the forward direction the shape of output characteristics is similar to that of BJT and have the controlling parameter is gate-emitter voltage VGE because IGBT is a voltage controlled device. The device developed by combining the areas of field effect concept and technology. CIRCUIT DAIGARAM:

EEE Department, SVEC, Tadepalligudem

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Power Electronics & Simulation Lab

PROCEDURE : TRANSFER CHARACTERISTICS : 1) Make connections as per the circuit diagram. 2) Initially keep V1 and V2 minimum and set V1 ( VCE1) = 10V. 3) Slowly vary V2 i.e., VGE and note down IC and VGE reading for every 1V. 4) Repeat the same procedure for different values of VCE and draw the graph VGE vs. IC . COLLECTOR CHARACTERISTICS :1) Initially set V2 i.e., VGE to 5V. Slowly vary V1 and note down IC and VCE . 2) For a particular value of VGE1 there is a pinch off voltage VP between collector and

emitter. 3) Repeat the same for different values of VGE and draw the graph between VCE vs IC

MODEL GRAPH:

EEE Department, SVEC, Tadepalligudem

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Power Electronics & Simulation Lab TABULAR FORM :

S.NO VCE1= VGE (V) IC (mA)

VCE2= VGE (V) IC (mA)

S.NO VGE1= VCE (V) IC (mA)

VGE2= VCE (V) IC (mA)

RESULT :

(c) CHARACTERISTICS OF MOSFETEEE Department, SVEC, Tadepalligudem Page 7

Power Electronics & Simulation Lab

AIM: To plot the input and transfer characteristics of a MOSFET to find ON state resistance and the transfer conductance. APPARATUS: 1) MOSFET IRF 740 2) Resistors 10K/25w, 75/25W, 4K/25W 3) DC voltmeter 0-50V 4) DC voltmeter 0-15V 5) DC ammeter 0-500mA THEORY: A metal oxide semiconductor field effect transistor is a recent device developed by combining the areas of field effect concept and technology. The transfer characteristics of MOSFET shows the variation of drain current ID as a fuction of gate source voltage VGS. The device is in OFF state upto some voltage called threshold device voltage. The output characteristics of Power MOSFET indicate the variation of Drain current ID as a function of Drain source voltage VDS as a parameter. This device combines into advantages of IGBT and BJT. So this device has high impedence and low ON state power like BJT. It is a new development in the ared of power MOSFET technology. All the devices are mounted on proper heat sink. Each device is protected by snubber circuit. PROCEDURE: TRANSFER CHARACTERISTICS: 1) Make connections as per the circuit diagram. 2) Initially keep V1 and V2 minimum and set V1 ( VDS1)= 10V. 3) Slowly vary V2 i.e., VGS and note down ID and VGS reading for every 1V. 4) Repeat the same procedure for different values of VDS and draw the graph V GS vs ID . COLLECTOR CHARACTERISTICS:1) Initially set V2 i.e., VGS to 3.5V. 2) Slowly vary V1 and note down ID and VDS . 3) For a particular value of VGS1 there is a pinch off voltage VP between drain and

source.

4) Repeat the same for different values of VGS and draw the graph between VDS vs ID

EEE Department, SVEC, Tadepalligudem

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Power Electronics & Simulation Lab CIRCUIT DAIGRAM:

MODEL GRAPH:

TABULARFORM:EEE Department, SVEC, Tadepalligudem Page 9

Power Electronics & Simulation Lab TRANSFER CHARACTERISTICS :

S.NO VDS1= VGS (V) ID (mA)

VDS2= VGS (V) ID (mA)

DRAIN CHARACTERISTICS: S.NO VGS1= VDS (V) ID (mA) VGS2= VDS (V) ID (mA)

RESULT :

2. GATE FIRING CIRCUITS OF SCREEE Department, SVEC, Tadepalligudem Page 10

Power Electronics & Simulation Lab AIM: To study and compare resistance firing circuit with the resistance-capacitance firing circuits. APPARATUS: 1) Control HWR and FWR using resistance circuits. 2) Rheostat 50/2A 3) CRO 4) connecting wires THEORY: The most common method for controlling the onset of conduction in an SCR is by means of gate voltage control. The gate control circuit is also called as firing or triggering circuits. These gating circuits are usually low power electronic circuits. The firing circuit should fulfill the functions. An SCR can be switched from OFF state to ON state in several ways. These are forward voltage triggering, dv/dt triggering, light triggering is used in some applications particularly in a series connected string gate triggering is the most common method of turning ON the SCR at desired instant of time. PROCEDURE: R-TRIGGERING: 1) Make connections as per the circuit diagram. 2) Connect the rheostat of 50/2A between the load points. 3) Vary the control pot and observe the voltage waveform across the load, SCR and different points of circuits. 4) We can vary the firing angle from 0 to 90 degrees only in R-triggering. In this synchronized firing angle can be obtained easily and economically in the halfcycle of the supply. 5) But there is a drawback that firing angle can controlled at the most at 900 since the gate current is in phase with the applied voltage. 6) A resistance is connected in series with the control pot so that the gate current does not cross the maximum possible value IG max. 7) Draw the waveform across the load and device for different values of firing angles.

RC-TRIGGERING: 1) Connect a capacitor to R-triggering circuit to realize RC triggering.EEE Department, SVEC, Tadepalligudem Page 11

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