EEE-454, Power Electronics Laboratory

Experiment 1

Switching Mechanism of Unidirectional Power Switches

Part 02


2. MOSFET AS A Switch:


EQUIPMENT:

  1. MOSFET - [Model: IRF 840].
  2. Resistor - [1K].
  3. Ceramic Resistor - [220Ω]
  4. Power Supply - [10V].                                
  5. Connecting Wire.
  6. Multimeter.
  7. Trainer Board.
  8. Variable DC Power Supply.


CIRCUIT DIAGRAM: 



Fig. MOSFET as a switch.


IG = (VGG - VGS)/RG, ID = (VDD - VDS)/RL

a. We set RL=220 Ohm (ceramic resistor), VDD=30V, and VGG from 0to 10V, Record VGG, VGS, VDS, IG, ID. When VD= 0, the switch is ON and ID= (VDD - 0)/RL, and it will not change unless RL or VDD is changed.

b. Repeated (a.) with RL=100 Ohm and 50 Ohm respectively.


DATA TABLE:


VGG

VGS

VDS

IG ­= (VGG­ - VGS)/RG

ID = (VDD – VDS)/RL

0.1 V

31.5 mV

9.67 V

0.068 mA

1.5 mA

1.1 V

0.9 V

9.71 V

0.2 mA

1.32 mA

4.0 V

3.5 V

9.70 V

0.5 mA

1.36 mA

5.0 V

4.33 V

6.5 V

0.67 mA

15.9 mA

5.3 V

4.5 V

239.2 mV

0.8 mA

44.36 mA

6.3 V

5.5 V

5.4 mV

0.8 mA

45.43 mA

9.7 V

8.6 V

2.7 mV

1.1 mA

45.44 mA



PRACTICAL WORK:




DISCUSSION: This lab is related to how MOSFET works as a switch. We can use a MOSFET as a switch. By using a MOSFET as a switch, we can automate the process of switching or switching on or off the load remotely operated instead of using an electromechanical switch that is operated by hand. While doing this experiment, we follow all the rules of the laboratory. First of all, we connect all equipment by following a circuit diagram. Then we connect all the equipment with the AC supply for our experiment. The two MOSFETs are configured to produce a bi-directional switch from a dual supply with the motor connected between the common drain connection and ground reference. When the input is LOW the P-channel MOSFET is switched ON as its gate-source junction is negatively biased so the motor rotates in one direction. We take all the values perfectly and put them on the table. We are very careful to take the value of voltages and currents. Sometimes multimeter was not capable to read the short-range value of current. So, we take an effective ammeter to measure the short range of the current value. Finally, we disconnect all the connections carefully and return the equipment to the lab assistant.



PART - 01 CLICK HERE