Week -2

Aim:

• To create a simulink model of doorbell using solenoid
• To create a simulink model using a thermistor to record temperature

Objective:

Doorbell

• To create a simulink model using solenoid block
• The condition used is to halt 2 secto observe the movement of plunger

Thermistor:

• To create a simulink modelusing thermistor block
• The thermistor is used to sense temperature of heater to turn ON or OFF the fan as per input conditions

Condition for Operation:

Doorbell model:

• The switch is closed for 2 seconds and it is released.

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 temperature > 25 C ,else OFF

Doorbell simulink model:

Working:

• Pulse generator is used to give input condition
• Simulink to PS convertor is used to pass input signal from simulink to simscape block through the switch
• The input signal is given through switch and battery is connected to a solenoid to generate the magnetic field for plunger movement and switch is connected to electrical reference as ground.
• The plunger movement is observed using the translational motion sensor
• The output of the solenoid block is given as inout to motion sensor whose output is observed through scope
• Translation reference block and solver configuration is used to solve the model with simscape block
• Display block shows the last value of output

Inputs:

Outputs:

Solenoid value setting:

Plunger position:

The value of damping is changed to eliminate the excessive oscillations and vibrations for smooth signal intensity. Thus by changing the input parameters to get smooth intensity signal.

Result:

The model is run for 10 seconds. The plunger will be at 0 position due to the time delay of 2 sec initially.Then the plunger will undergo displacement and again back to zero. The process repeats till the stop time of 10 seconds.

Thermistor Simulink model:

Working:

• NTC thermistor is used to sense temperature change in heater & turn on or turn off the fan
• The given temperature range the repeating sequence block is used with the sample time of 10 sec with the required temperature values.
• To convert the Simulink block to Simscape the simulink to PS converter is used to convert the physical signal to thermistor through temperature source
• The thermistor uses resistance for temperature sensing, a resistor is connected in series with thermistor and voltage is across the resistor by connecting voltage sensor parallel to resistor
• Battery is connected as an electric source reference
• Constant output for voltage sensor is 298K which is the threshold value for switch to turn the fan ON or OFF
• If the value is above 298 K then the switch is activated to turn the fan ON
• When the temperature signal is greater than 298 K its resistance decreases and voltage increases
• Switch with 3 inputs is used and value of threshold is given in middle port
• Two constant blocks of 1 and 0 are connected to turn switch ON and OFF
• Now when condition is satisfied the switch will ON and the signal will be 1 which can be seen through scope
• Different reference blocks and solver configuration blocks are used to solve the simscape model

Inputs:

Output graphs:

Results:

• From the graph it is seen that fan is turned on if the temperature is above 25 C
• When it goes below then the fan is turned off