Week -2

Make a Simulink model of Doorbell using solenoid block with the following details:

Aim:

To Simulink model of Doorbell using solenoid block and thermistor to sense the temperature of a heater & turn on or turn off the fan as per the temperature condition.

Doorbell using Solenoid:

The Solenoid is a electromagnet. On passing current through the conducting wires a magnetic field is generated around it which attracts magnetic materials.This phenomenon is used in the bell. when the switch of the bell is pressed the current passes through the circuit, exciting the electromagnet and pulling the plunger towards the metal portion.This produce a ringing sound.

SIMULINK MODEL:

Condition:

Switch is closed for 2 second and then released

Model Explanation:

A pulse generator is given as input with the following specification:

The condition was that the bell is engaged for 2 s and then released same was implemented by giving period as 4 second and pulse width as 50% of 4 second. i.e, 2 seconds. Phase delay was given as 2 seconds, So the simulation starts from the unengaged condition of switch.

Pulse generator:

Solenoid:

The Solenoid block represents the electrical characteristics and generated force for the solenoid in the following figure:

The return spring is optional. To remove the effects of this spring from the model, set the Spring constant parameter to 0.

To show the direction in which the solenoid acts, the block icon changes dynamically based on value of the Motion direction under excitation parameter.

Input Current and Voltage Waveform:

.

Ideal Translational Motion Sensor block:

• The Ideal Translational Motion Sensor block represents a device that converts an across variable measured between two mechanical translational nodes into a control signal proportional to velocity or position. You can specify the initial position (offset) as a block parameter.The sensor is ideal since it does not account for inertia, friction, delays, energy consumption, and so on.
• Connections R and C are mechanical translational conserving ports that connect the block to the nodes whose motion is being monitored. Connections V and P are physical signal output ports for velocity and position, respectively.The block positive direction is from port R to port C. This means that the velocity is measured as v = v_R – v_C, where v_R, v_C are the absolute velocities at ports R and C, respectively.
• As we want the circuit to be close only in the interval of 2 seconds a switch block is used. The Switch block has a threshold value of 0.8.The threshold of the pulse generator is 1. The switch will only close if the value is more than 0.8. Then connected to Solenoid block which contains the plunger arrangement. Initially when the plunger is away from C the value of X is 5mm and when the plunger is near C the value of X is 0 mm. This can be seen from the output graph of plunger distance vs time.The position of the plunger is obtained by using the Ideal Translation Motion Sensor.

Velocity vs Time:

Position Vs Time:

When Switch is closed there may be Some electromagnetic Interferance due to that Spike may appear

2. Use a thermistor to sense the temperature of a heater & turn on or turn off the fan as per the below conditions

Signal Builder(Input):

In Signal Builder, giving input values as per the given condition

Given Inputs:

At Point1- Time 0 sec - Temperature-293K

At Point2- Time 10 sec - Temperature-293K

At Point3- Time 10 sec - Temperature-300K

At Point4- Time 30 sec - Temperature-300K

At Point5- Time 30 sec - Temperature-296K

At Point6- Time 50 sec - Temperature-296K

Simulink Model:

Explanation of Model:

Input are set in the Signal Builder and connected with Temperature controlled Source for maintaining the specified temperature difference across the source.Then input temperature flows through thermistor.

Thermistor is connected with Resistor, ensure that thermistor connected with positive terminal of the resistor and the voltage across the resistor is given by V(+) - V(-), and the sign of the current is positive when flowing through the device from the positive to the negative terminal.This convention ensures that the power absorbed by a resistor is always positive. Connected the Positive terminal of Voltage source to Positive terminal of the thermistor and connected the negative terminal of Voltage Source to negative terminal of Voltage Sensor and Resistor to get the values from the Voltage Sensor (Like Series Connection).

Output terminal of the voltage sensor is connected with Switch.Using the Switch Parameter for giving the condition as Fan must be ON if the temperature above 25 C off otherwise.Output is Successfully executed by connecting with Scope as per the given condition.

Voltage Sensor Measurement:

Output:

for 0-10 sec fan is in OFF condition, because temperature is 293k which is below 298k.After 10 sec temperature goes to 300K, So fan will turn on, because temperature exceeds 298k. After 30 secs fan will turn OFF because temperature goes to 296k which is below 298k.

From 0-10 sec lamp shows:

From 10-30 sec lamp shows:

From 30-50 sec lamp shows:

In the Simple dc motor Fan circuit we get Angular velocity and Angular displacement