Week -2

AIM:

1. To Make a Simulink model of Doorbell using solenoid block.
2. To use a thermistor to sense the temperature of a heater & turn on or turn off the fan

OBJECTIVE:

1. To Create a situation where the switch is closed for 2 seconds and then released and then observe the physical movement of the plunger.
2. To sense the temperature of a heater by using the condition given below 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.

THEORY:

When the switch is energised the current flows through the circuit and the doorbell rings, if it is deenergised the doorbell does not ring. It has an electromagnet internally where the magnetic field is generated by the electromagnet when the current passes and releases the plunger to ring the bell.

Solenoid – converts electrical energy into mechanical energy.

BLOCKS USED:

• Pulse generator - It generates square wave pulses at regular intervals, the block have parameter, amplitude, pulse width, phase delay and determine the shape of the waveform.
• Simulink - PS converter- Converts Simulink input signal to a physical signal
• Switch – The switch is controlled by an external physical signal is greater than the threshold then the switch is opened otherwise switch is closed.
• Battery – It gives voltage to the system.
• Solenoid Block – It shows the position of the plunger with respect to which depends on the condition gets true.
• Ideal translational motion sensor – This block converts a variable measured between two mechanical translational modes into a control signal is proportional to velocity and position.
• Mechanical & electrical reference – This gives reference to the respective signals.
• Scope – This shows the output in a graph or plot with respect to simulation time.
• Solver Configuration – Each physical network represented by a connected simscape block diagrams requires solver configuration. Solver configuration runs a background equation for every simscape block.

SIMULINK MODEL FOR DOORBELL:

SIMULINK MODEL EXPLANATION FOR DOORBELL:

• The pulse generator is used to create square wave pulses at regular intervals. This block give waveform parameters such as amplitude, pulse width, period and phase delay, determines the shape of the output waveform.
• The switch block is controlled by external physical signal. If the external signal is greater than the threshold, the switch is closed otherwise switch is opened.
• The positive terminal of the switch is connected to switch and the negative terminal is connected to the electrical reference.
• The solenoid block is connected with switch and battery, the electrical circuit is closed. The common port C is connected with the mechanical reference.
• The ideal translational sensor is connected with the solenoid block R to observe the movement of the plunger.
• Scope is connected with ideal translational sensor to get the output result.
• PS Simulink converter is used to convert the physical signal into Simulink signal.
• Each physical network is represented by a simscape block requires solver setting information from the simulation that is given by solver configuration block.

The above figure is obtained by running the Simulink model and when seeing the scope block it shows the pulse generated after 2 seconds time interval.

• Now run the model and double click on scope1 block which is connected to the ideal translational sensor

• This represents amplitude is 1 that means switch will close and current start flows, when amplitude is 0 that means switch will open and current stop flowing.
• Our objective is to observe the change in plunger after 2 seconds.
• Pulse generator block generates Simulink as output so we can convert by using the Simulink ps converter block.
• The switch takes only the physical value as inputs, the port p of ideal translational motion sensor block to the scope1 block and a solver configuration block is connected as which generates equations and solve the whole mode internally to give the result.
• Finally we get the result

THERMISTOR:

• A thermistor is a resistance thermometer where resistance is dependent on temperature.
• Thermistor are easy to use, inexpensive, sturdy. They are used in hot or cold appliances.
• It is widely used in Pulp and paper industries, cement industry
• It has wide range of appliances.

SIMULINK MODEL FOR THERMISTOR:

SIMULINK MODEL EXPLANATION OF THERMISTOR:

• Signal Builder block is used to input the values as per given conditions
• At point 1,Time=0 seconds, Temperature=293 K
• At point 2,Time=10 seconds, Temperature=293 K
• At point 3,Time=10 seconds, Temperature=300 K
• At point 4,Time=30 seconds, Temperature=300 K
• At point 5,Time=30 seconds, Temperature=296 K
• At point 6,Time=50 seconds, Temperature=296 K

• Controlled Temperature source represents an ideal source of thermal energy, that can maintain a controlled temperature difference regardless of the heat flow rate.
• The temperature difference is set by the physical signal port S. A positive temperature difference causes the temperature at port B to be greater than the temperature at port A.

• Thermistor is a type resistor whose resistance is based upon temperature

linear resistor is used is used in order to control the amount of current from the battery.

• The voltage sensor is used to convert the voltage measured between two points into a physical signal.
• Voltage source which represents dc or ac electrical reference block is given Solver Configuration.
• Each physical network represented by a connected simscape blocks requires solver setting information for simulation

CONCLUSION:

• The Physical movement of the Plunger of solenoid was observed when switch is close for 2 seconds .
• Simulink particularly helps to improve the performance by Analysing it on plot and changing the suitable
• configuration, as in above case of Solenoid operated bell "Spring constant" and "Damping" was varied.
• Thermistor is used to sense the temperature of a heater & turn on or turn off the fan as per above conditions
• Therefore the fan conditions are executed by SWITCH block and plotted in scope block.