Week -2

WEEK 2

AIM:

• To make a Simulink model of doorbell using a solenoid block.
• To build a model using a thermistor to sense the temperature.

OBJECTIVE:

• To make a Simulink doorbell model using a solenoid block with a situation of 2-sec halt & then continued further to observe the physical movement of the plunger.
• To build a model using a thermistor to sense the temperature of a heater & turn on or off the fan as per conditions mentioned in the problem for the Simulink model.

OPERATING CONDITIONS:

A. For Door Bell model:

The switch is closed for 2 seconds and then released.

Here, Doorbell consists of the main parts which include a solenoid, battery as a source, switch & bell. Here, the important part is the Solenoid on which the working of the plunger i.e movement depends. A solenoid is just an electromagnet where the coiled wire surrounds a metal piston. The piston contains magnetically conductive metal, so it can be moved backward or forward by the electromagnetic field. A magnetic field is produced here with the help of battery source.

SIMULINK MODEL:

Working:-

• Here we use a pulse generator for the input condition given in the question.
• To pass the input signal from the Simulink block to the simscape block through the switch, a Simulink to PS converter block is used.
• The input signal is provided to a switch. A battery is connected to a solenoid to generate the magnetic field for movement of the plunger and the switch with electrical reference as a ground.
• To track the position of the plunger, a Translational motion sensor is used. The output of the solenoid block from connector R is given to the motion sensor as an input which will ultimately give an output of position that can be observed in the graph through the scope block.
• Translational Reference block is used for fixed point and also solver configuration is provided to solve the model with simscape block. In addition, the display block is applied which shows the output for the last value.

The above model uses the following blocks:

1.Pulse Generator

The Physical signal controls the switch shown below

The blue colored circuit is the electrical circuit is controlled by the switch. the circuit is closed the current flows from the battery to the solenoid plunger.

Doorbell mechanism

Solenoid

Ideal Translational Motion Sensor

Results:

Position Signal

Velocity Signal

B. For the Thermistor model:

Temperature source: 20 °C from 0 to 10 seconds, 27 °C from 10 to 30 seconds, 23 °C from 30 to 50 seconds.

Fan conditions: ON if the temperature above 25 °C, OFF otherwise.

A thermistor is a resistance thermometer or a resistor whose resistance is dependent on temperature. The term is a combination of “thermal” and “resistor”.

There are two types of thermistors: Negative Temperature Coefficient (NTC) and Positive Temperature Coefficient (PTC). With an NTC thermistor, when the temperature increases, resistance decreases. Conversely, when the temperature decreases, resistance increases. This type of thermistor is used themost.

A PTC thermistor works a little differently. When temperature increases, the resistance increases, and when temperature decreases, resistance decreases. This type of thermistor is generally used as a fuse.

SIMULINK MODEL:

Temperature is

20 °C from 0 to 10 seconds,

27 °C from 10 to 30 seconds,

23 °C from 30 to 50 seconds.

Fan should be on if the temperature above 25 °C, off otherwise.

Result:

CONCLUSION:

1) For the Doorbell model, from the graph, it can be concluded that the situation for 2 seconds delay is satisfied and the plunger movement is also observed.

2) For the Thermistor model, from the angular velocity graph, we can conclude that the fan is in motion only when the thermistor will sense the temperature greater than that of the 25-degree Celcius which satisfies the required conditions.

https://drive.google.com/drive/folders/17LL1D7KinIgDDPnBo-Hsfd_zid0dn_vk