Week -2

Aim:- 1. A Simulink model of doorbell using solenoid block.
              2. To use a thermistor to sense the temperature of a heater and turn on or turn off the fan as per the condition.

        1. A Simulink model of doorbell using solenoid block.

Objective:

• When the switch is closed the electromagnet receives electric power from the battery and pulls the metal arm to hit the bell producing sound. 

Theory:

• In the above arrangement, when the switch is closed the electromagnet receives electrical power from the battery and pulls the metal arm to hit the bell producing the sound. A situation where the switch is closed for 2 seconds and then released. And observe the physical movement of the plunger.
  

Simulink model of Doorbell:

             

Explanation of Simulink:

• The command is given by a pulse generator to the circuit. We had connected a scope to display the pulse which was generated by a pulse generator.
• Then we had to use a simulink PS converter to convert the input simulink signal into physical signal.
• Simulink PS converter is now connected to a switch which is opened and shut by pulse which is generated by pulse generator. The power to the circuit is given by the battery.
• The battery end terminal is connected to the electrical references.
• Solver configuration is given to solve configuration equations.
• A Solenoid converts electrical energy into mechanical work. One end of the solenoid converts with a switch and one is connected with electrical reference.
• The other end of the solenoid is connected with an ideal translational motion sensor.
• ideal translational motion sensor a device that converts an across variable measured between two mechanical translational nodes into a control signal proportional to acceleration, velocity, or position.
• And we had connected a mechanical translational reference with solenoid and ideal translational motion sensors.
• After that we had PS Simulink to convert the physical signal into Simulink signal.
• Here, how we had got the result in the scope, as represented in the graphical form.

Result:

• Solenoid output
  
• Pulse generated output
  

       2. To use a thermistor to sense the temperature of a heater and turn on or turn off the fan as per the condition.

Objective:

• Use a thermistor to sense the temperature.
• To turn on or turn off the fan as per given temperature coundistion.

Given conditions:

• Temperature source: 20c from 0 to 10 seconds.
• Temperature source: 27c from 10 to 30 seconds.
• Temperature source: 23c from 30 to 50 seconds.
• Fan conditions: a fan should be on if temperature above 25c. and off otherwise.

A simulink model of thermistor sensor

Explanation of simulink blocks

• Components:
  1. Signal builder
  2. Controlled temperature source
  3. Thermal reference 
  4. Solver configuration
  5. Thermistor
  6. Resistor
  7. Battery
  8. Electrical reference
  9. Voltage sensor
  10. Constant
  11. Switch
  12. Simulink PS converter
  13. PS simulink converter
  14. Scope
• Signal builder is used to generate a Groupe signal to a Simulink block. To convert a Simulink PS converter to convert the input Simulink signal into physical signal.
• Then it is connected to a controlled temperature source, an ideal source of thermal energy that is powerful enough to maintain specified temperature difference across the source regardless of the heat flow consumed by the system.
• Other end is connected to a thermal reference.
• A solver configuration is attached to an ongoing circuit line to the thermistor.
• The thermistor therefore heats up, and its resistance decreases thereby increasing the voltage across the PWM reference pins.
• Supply is given by battery to the thermistor and the other end is connected with resistor and voltage as shown in the given figure.
• A voltage sensor is a device that is used to measure the voltage of an electrical circuit or system.
• To convert a physical signal to a Simulink signal we had attached a PS Simulink converter.
• To set a threshold value we had added a scope before the switch, after getting a maximum value of 27c we had set a threshold at max point to start a fan according to the max temperature.
• The constant value is provided to the switches to match the temperature conditions.
• A result is shown in the scope to show the output plot of the graph of the actual conditions.

Different conditions of time vs temperature

1. T1 = 20c = 293.15k – 0 to 10 sec
2. T2 = 27c = 300.15k – 10 to 30 sec
3. T3 = 23c = 296.15k – 30 to 50 sec
   
   

Result:

Conclusion:

• A Threshold value is 0.012559Hz.
• From 0 – 10secound fan is off because the temperature is 20c or 293.15k.
• Which is below 23c or 296.15k, after 10 second it goes to 27c or 300.15k so the fan will turn ON because u2 is greater than the threshold.
• After 30 second fan will turn OFF because the temperature goes down.