Challenge

Week -2

PPalash Dhore11 Aug 2021

A).

1. Title :-

Make a Simulink model of Doorbell using solenoid block.

2. Introduction :-

Simulation of door bell using solenoid block with following condition :- The switch is closed for 2 seconds and then released. Observe the physical movement of the plunger.

While simulating this model following blocks are used :-

DC source
Switch
Solenoid
Ideal translational motion sensor
pulse generator
PS-Simulink converter/Simulink-PS converter
Electrical refrence
Mechanical translational refrence
Scope
Solver configuration

3. Workdone :-

In this simulation switch is controlled by external signal that is pulse generator.
As per given condition in the problem that switch is closed for 2 seconds and then open so,accordingly pulse generator block is modified .
DC source is used with amplitude of 12 V.
To sense the physical movement of plunger an ideal translational motion sensor is used.It has two outlet one for position and other for velocity.
Used position outlet to sense the physical movement of plunger.
To, see the results in scope use ps - simulink converter as motion sensor is from simscape library and scope is from simulink library.
For mechanical block we use mechanical refrence and for electrical block we use electrical refrence.

4. Result :-

As we see from the above graph , intially plunger is at rest that is at 0 value.
As switch is closed for 2 second the elctromagnet get charged and it attracts the plunger to hit the bell.So, for 0 to 2 second the plunger position
changed as shown in graph.
After 2 second as switch is open plunger goes to its intial position that is zero value.

5. Conclusion :-

Comprehensive simulation of above model is carried out in MATLAB/SIMULINK software and analysis is done thoroughly.

B).

1. Title :-

Use a thermistor to sense the temperature of a heater & turn on or turn off the fan.

2. Introduction :-

Simulation is done by considering the following condition :-

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.

While simulating this model following blocks are used :-

Signal builder .
Ideal temperature source.
Thermistor..
DC voltage source.
Resistor.
Solver configuration.
Thermal and electrical refrence.
Scope,Display.
goto,from.
Switch ,PS - simulink ,constant.
voltage sensor and pulse generator.

3. Workdone :-

Signal builder block is used to generate the input signal as per given condition .
This input is converted into physical signal using simulink -PS converter,and given to ideal temperature source.
output of ideal temperature source is then given to thermistor.
Thermistor is the sensor which sense the temperature as input and gives output in terms of resistance with respect to different temperature change.
A voltage sensor is used to sense the voltage across thermistor for different temperature .
As per operating condition of fan 298k is the threshold value, above which fan operate and below it is off.
So, by considering this condition a resistor of value 1005.9 ohm is connected in series with DC voltage source.Calculation of resistor is done by this formula :-
R(T) = R0*exp(B*(1/T-1/T0)
B= 3500k ,T0 =298.15k ,R0 = 1000 ohm, T =298k.
The voltage across this resistor is acts as thershold for switch and its value is 5.72V.
Switch has three port . port 1 and port 2 acts as data port .port 2 is control signal port , threshold value is given to port 2.