Week -2
AIM :- 1.Make a Simulink model of Doorbell using solenoid blocK &
2.Make Simulink model Use a thermistor to sense the temperature of a heater & turn on or turn off the fan.
Ojective:-
1.Make a Simulink model of Doorbell using solenoid block with the following details:
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 sound.
Create a situation where the switch is closed for 2 seconds and then released. Observe the physical movement of the plunger. Assume remaining parameters.
Theory :-
DOORBELL :- A doorbell is a singnaling device typically placed near a door to a building's entrance. When a visitor presses a button the bell ring inside the building , alerting the occupant to the presence of the visitor. The heart of adoorbell is an electromagnet. Electromanget are coil of wire wrapped areound a small peice of magnet metal. When electricity passes through the wire . it creates a magnetic metal. when you press a doorbell button, you complete an electrical circuit that allow household electricity to flow through the doorbell's internal electromagnet. the magnetic feild generated by the electromagnet is then used to power a mechanism that creates the doorbell sound.
Doorbell are low voltage device. this mean they require relatively little energy to operate. An important part of a doorbell mechanism is the transformer. the transformer converts regular 120volt household current to the lower voltage (usually somewhere between 6-16 volts) required by the doorbell.
Solenoid:- A solenoid is a 3-dimensional structure of wire. When this wire is wrapped around a metallic block in a coil and electricity is passed through it, it has some special magnetic properties. electromagnetic induction makes it an electromagnet that can be switched on or off. the side in which the current appears to be passing clockwise is the South Pole, and the side in which the current seems to be passing anticlockwise is the Northern Pole. The solenoid works just like a bar magnet and therefore has many uses. this principle is used to create valve, among other things. where the solenoid operates an electric switch, it is a relay.
Fig 1 :- Simple diagram of doorbell
Fig 2 :- Traditional doorbell
Simulink Model of Objective:-
Fig 3:- Simulink Model of Objective 1
1. Pulse Generator:- The pulse generator block generates square wave form pulse at regular intervals. the block waveform parameter, amplitude, pulse width, period, and phase delay, determine the shape of the output waveform.
2.Simulink-PS Converter:- Convert the unitless Simulink input signal to a Physical Signal.
3.Scope:- Display signals generated during simulation.
4.Switch:- Switch controlled by an external physical signal.
5.Solenoid:- Model electrical characteristics and generated force of solenoid.
6.Battery:- The battery block represents a simple battery model.
7.Ideal Translation Motion Sensor:- The Ideal Translation Motion Sensor block represents a device that convert an across variable measured between two mechanical translational node into a control signal proportional to velocity or position .The sensor is ideal since it does not account for inertia, friction, delay, enegry consumption, and so on.
8.Solver Configuration:- The Solver Configuration block specifies the solver parameter that you can being the simulation.
9.PS-Simulink Coverter:- Convert physical signal into Simulink output signal.
10.Electrical Reference:- The electrical reference block represents an electrical ground. Electrical conserving port of all the block directly connected to the ground must be connected to an electrical reference block.
11.Mechanical Translational Reference:- The Mechanical Translational Reference block represents e reference point, for all Mechanical Translational port. All translational ports that are rigidly clamped to the frame must be connected to a Mechanical Translational Reference block .
Model Explanation:-
1.The pulse generator is used to give the signal input where, Amplitude=1,Period=4sec,Pulse width=50%,and Delay=2sec.
2.After that, the input signal is converted into physical form with the use of "Simulink-PS Converter" and futher send to the switch of the electrical circuit.
3.The electrical circuit consist of solenoid, a battery ,and a switch. One end of the solenoid is connected to the battery and its other end is connected to the switch. An electrical reference is provided in the electrical circuit.
4.The mechanical part of the solenoid is connected to an ideal translation motion sensor and Mechanical Translational Reference.
5.The P-port of the sensor makes a connection with the "PS-Simulink Converter" to provide the output in the signal form. Further, the converter is connected with scope to display our output signal.
6.A solver configuration is connected to an electrical circuit to solve all parameter before the beginning of the simulation.
Fig-4:- Pulse generator
Fig-5:- Signal input in doorbell
OUTPUT:-
Fig-6:- Output of doorbell
Objective 2:-
2.Make Simulink model Use a thermistor to sense the temperature of a heater & turn on or turn off the fan.
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
Theory:- A thermistor (or thermal resistor) is defined as a type of resistor whose electrical resistance varies with temperature changes. Although all resistors resistance will fluctuate slightly with temperature, a thermistor is particularly sensitive to temperature changes.
Thermistors act as a passive component in a circuit. they are an accurate, cheap,and robust way to measure temperature. while thermistors do not work well in extremely hot or cold temperature, they are the sensor of choice for many different application.
fig:- Different types of thermistor
Simulink Model of Objective 2:-
Fig:- Simulink model of Thermistor
This figure shows the representation of thermistor connection which senses the temperature of a heater and passes the signal to a switch where a threshold limit is already set. if the temperature is above or equal to the threshold limit, then it gives "1" as output which is "Switch On" . ifthe temperature is below the threshold limit, then it will give "O" as output which mean "Switch off" The input signal is generated with the help of a "Signal Bulider" block .This input signal is created according to the conditions given inthis challenge. The condition are as following:
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.
Here the temperature is converted in Kelvin from degree Celcius because the signal converter does not take °C value as input. I also have to set the signal unit as "Kelvin" in Simulink-PS Converter.
THE FORMULA FOR CONVERSION : 1°C=273.15 K
The Signal 1 is :-
From 0-10 sec - Temperature is 293.15 K
From 10-30 sec - Temperature is 300.15 K
From 30-50 sec - Temperature is 296.15 K
Fig:- Input signal create on Signal Builder Block
Fig:- Switch(Threshold limit is set here)
Model Explanation :-
1.At first the signal is created in "Signal Bulider" and furter passes to "Simulink-PS Converter" to covert the input signal into the physical signal.
2.this physical signal is connected to a block " Controlled Temperature Source" .This block is connected to the thermistor and a "Thermal Reference" block.
3.The thermistor is a part of an electric circuit where a battery , a voltage sensor , a resistor connected parallel to the voltage sensor, an electria; reference are connected to make a complete circuit. A solver configuration is connected to that electrical circuit to solve all parameters before the beginning of the simulation.
4.The voltage sensor senses the temperature in the form of voltage and sends the data to its port "V".
5.From this port we get our output and send it to two different "PS-Simulink Converter" .
6.From converter-1 the signal is sent to the threshold switch the threshold limit then it gives "1" as output which is "Switch On" If the temperature is below the threshold limit then it will give "0" as output which means "Switch Off" The input signal is generated with the help of a "Signal Builder" block.
7.The switch is connected to the scope where we can see our output plot.
8.From converter-2 it converts the physical signal into a Simulink signal and sends the voltage data from the Voltage sensor to display. This display gives us the threshold value of voltage. this value is set in the switch.
OUTPUT:-
It can be seen that the value of the signal is "0" from 0-10 sec because in this time the temperature was 20°C which is below 25°C means "Switch Off the fan". After that the signal value gives "1" as output from 10-30 sec because in this time the temperature was 27°C which is above 25°C means "Switch On the fan". The value of the signal is again goes to "0" from 30-50sec because in this time the temperature was 23°C which is below 25°C means "Switch Off the fan".
Fig:- Output signal