Week -2

Simulink model of Doorbell using solenoid

AIM:

Make a Simulink model of Doorbell using solenoid with a switch should be closed for 2 sec and then released.

BLOCKS USED IN MODEL:

• Scope
• Battery
• Pulse generator
• Switch
• Solenoid
• Mechanical translational reference
• Solver configuration
• Ideal Translational motion sensor
• PS Simulink converter
• Simulink PS converter
• Electrical reference

EXPLANATION:

When a Switch is pressed, the electrical circuit becomes closed circuit. Hence Current flows through the solenoid which inturn produces electromagnetic field results in the produce of Doorbell sound.

SIMULINK MODEL:

Pulse Generator is the input signal given to the switch with a phase delay of 2 seconds. DC battery and switch forms a closed circuit connected with the solenoid. The physical signal from pulse generator is converted to Simulink signal and gien to the Switch. When the Solenoid is excited , this results in the motion of plunger. This plunger moments is monitored using the Ideal Translation motion Sensor by connecting R and C ports with the sensor respectively. The Simulink signal is converted to the physical signal and displayed in Scope.

Graph:

Conclusion:

The plunger movement as recorded by the scope is shown above. The simulation was run for 10 sec. It is observed that for every 2 sec interval, the bell is ringing.

Modelling of Thermistor Controlled Fan

AIM:

Make a Simulink model of a thermistor controlled fan with 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

Blocks used in Model:

• Signal builder
• Solver configuration
• Thermal reference
• Electrical reference
• Simulink-PS converter
• PS-Simulink converter
• Controlled temperature source
• Thermistor
• Battery
• Voltage sensor
• Resistor
• Switch
• Scope
• Display
• lamp
• constants

Explanation:

When the temperature of the heater becomes more than 25, then the fan Should be on.Otherwise, It should be in Off state.

Simulink Model:

We give the input signal using the signal builder block.The input signal is made in way to allow the given conditions.

The signal is being fed to the S port of the controlled temperature source usingthe Simulink-PS converter block. The A port is connected to thermal reference. The B port is connected to the thermal port T of the thermistor. A resistor isconnected in series with the thermistor. A voltage sensor is connected in parallel to the resistor. A battery is connected in this circuit followed by a electrical reference. The output from voltage sensor is being fed to display block using a PS-Simulink converter. The display block displays the threshold value being measured by the voltage sensor. This threshold is being fed to a 3 pin switch. Constants 0 and 1 are being fed to the other two pins in the switch. Finally a scope is connected to the switch and the output of switch is connected to the lamp.

Conclusion:

WHEN FAN IS ON:

The fan turns on when temp is greater than 25°C. The stop time is 25 seconds

The graph above shows that from 0 - 10 seconds, the temperature is 20°C and

the fan is off. The fan gets turned on from 10 - 30 seconds where the

temperature is 27°C .

WHEN FAN IS OFF:

The fan turns off when the temp is less than 25°C. The stop time is 50 seconds

In the above plot at 30 seconds, the fan goes off again as the temperature

reaches 23°C.

If the resistance across is less than the switch threshold value, then fan goes to

off state and the lamp turns to red. If the resistance across is greater than the

threshold, then fan goes to on state and the lamp turns green.