Week -2
AIM:
1.Make a Simulink model of Doorbell using solenoid block.
2.Use a thermistor to sense the temperature of a heater & turn on or turn off the fan.
1.
Objective:
In the arrangement, when the switch is closed the electromagnet receives electrical power from the battery and pulls the metal arm to hit the bell producing sound.
Create a situation where the switch is closed for 2 seconds and then released. Observe the physical movement of the plunger.
Solenoid:
A solenoid is a type of electromagnet, the purpose of which is to generate a controlled magnetic field through a coil wound into a tightly packed helix. Solenoid may also refer to a variety of Transducer devices that convert energy into linear motion.In simple terms, a solenoid converts electrical energy into mechanical work.
Main Components:
1.Solenoid
2.Switch
3.Battery
4.Bell with Plunger
Procedure:
1.Import the Battery,switch,Solenoid blocks to Simulink from the Library browser to make a connection of a Door bell.
2.Now connect the blocks of Battery and Solenoid with the positive terminals of Battery and Solenoid.Add the switch block between the Battery and the Solenoid to make an ON and OFF operation.
3.An 'Electrical reference' block is imported from the Library and connected to the negative terminal of the Battery which represents earthing of the circuit.
4.In order to sense the motion of the plunger an 'Ideal Translational Motion Sensor Block' is connected to the Solenoid.
5.In Solenoid 'R' and 'C' are two variable which represent plunger and the fixed point.Now the 'R' of Solenoid is connected to the 'R' of Motion Sensor to sense the motion of the Plunger and gives the Output from Solenoid.
6.'C' in Motion sensor is connected to the 'C' in Solenoid with a 'Mechanical Translational Reference block'.
7.As an input connects the 'Pulse Generator' to generate the signals to the switch for the operation.So when the switch gate is closed, the plunger moves with respect to the Input signals.
8.The input signals for the Pulse Generator are Amplitude '3', Period '2', Pulse width '50' and Phase delay '0' as the phase delay is 0 the Pulse will start from 0 for a period of 2sec.
9.To minimize the Damping effect in the Pulse Damping coefficient is adjusted to 5.
10.In order to convert the signal of Simulink value from the Pulse Generator into Physical signal for switch 'Simulink-PS converter' is used and vice versa which means 'PS-Simulink converter' to convert the signals from 'Ideal Translational Motion Sensor Block' to 'Scope' where it generates the Graph for change in position and 'Display' block to display the Numeric format.
11.The output 'P' from the 'Ideal Translational Motion Sensor Block' is connected to Scope and Display block.
Output:
As the Phase delay is 0 with a Pulse width of 50% of period and period of 2, the signal starts from 0 with a 2 sec period which means the signal starts from every 2 sec and Pulse width will be 1 as it was 50% of period.
2.
Objective:
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
Thermistor:
A thermistor is a resistance thermometer, or a resistor whose resistance is dependent on temperature. The term is a combination of “thermal” and “resistor”. It is made of metallic oxides, pressed into a bead, disk, or cylindrical shape and then encapsulated with an impermeable material such as epoxy or glass.
There are two types of thermistors:
1.Negative Temperature Coefficient: With an NTC thermistor, when the temperature increases, resistance decreases. Conversely, when temperature decreases, resistance increases. This type of thermistor is used the most.
2.Positive Temperature Coefficient: 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.
Procedure:
1.Import the Battery,Thermistor, Resistor, Voltage sensor blocks to Simulink from the Library browser to make a connection of a Temperature regulated Fan.
2.Battery positive terminal is connected to the 'Thermistor' positive terminal and the 'Resistor' is connected to the Thermistor and the negative terminal of the Resistor is connected to the Battery negative terminal.
3.'Electrical reference' block is connected to the negative terminal of the Battery which represents the earthing of a circuit.
4.'Voltage Sensor' block is connected parallel to the resistor to measure the voltage across the component.
5.To provide the Temperature to the System a 'Controlled Temperature Source' is used to maintain the controlled temperature difference regardless of the heat flow rate and it is connected to the Thermistor.
6.Now to provide the different temperatures to the system a 'Signal Builder' block is used to send the signals to the Temperature source as inputs.
7.In Signal Builder the inputs of temperature is given as
273K+20=293k - 0 to 10sec
273K+27=300K - 10 to 30sec
273K+23=296K - 30 to 50sec
8.'Temperature Source' is connected to the 'A' port of Controlled Temperature Source which represents an ideal energy source in a thermal network that can maintain a constant absolute temperature at the port regardless of the heat flow rate.'Solver Configuration' block is connected to the Temperature Source connection.
9.In order to convert the signal of Simulink value from the 'Signal Builder' into Physical signal for Controlled Temperature Source 'Simulink-PS converter' is used and vice versa which means 'PS-Simulink converter' to convert the signals from 'Voltage Sensor Block' to 'Scope' where it generates the Graph of output from the Voltage sensor.
10.From the above condition that Fan conditions are ON if the temperature is above 25 °C, OFF if temperature is below 25°C.In order to operate this condition we need a switch that can turn On when the temperature is above 25°C.
11.Import the switch from the Library and now connect the Middle port of the switch with the Output of PS-Simulink converter and other two ports with the constant blocks '1' and '0'.The threshold value for the switch will be the Voltage at 25°C to turn ON the Fan which is 2.01.
12.Now connect the Scope block and the Display block from the Switch
Output:
From the Graph it can be seen that Voltage changes with respect to the Temperature.So from the condition that Fan is to be turn ON only at above 25°C,the voltage at 25°C/298K is 2.01.
From this Graph it can be seen that Fan turns ON above 25°C in the period of 10-30sec.
