Week -2
Aim 1 - Make a Simulink model of Doorbell using solenoid block.
Objective - Switch is closed for 2 seconds and then released.
Observe the physical movement of the plunger.
Theory -
Doorbell - It is a device having mechanical and electrical component to produce sound on pressing a button. A switch is pressed manually to complete a circuit loop in which causes the current to flow through the circuit, While the switch is pressed a Solenoid generates electromagnet at desired space, which allows the plunger to move, due to which the bell produce sound.
Solenoid - A Solenoid is a device comprised of a coil of wire, housing, and a moveable plunger (armature). When an electrical current is introduced, magnetic field forms around the coil which draws the plunger in. More simply, a solenoid converts electrical energy into mechanical work output.
Explaination of Components used -
1. Battery - It is DC power supply which will power up the circuit.
2. Switch - It is a external physical signal controller.
3. Pulse Generator - It generates waveform parameters, Amplitude, Pulse Width, Period, and Phase delay, determine the shape of the output waveform.
4. Solenoid - It is a type of device which form electromagnet by a helical coil of wire whose length is substantially greater than its diameter, which generates a controlled magnetic field.
5. Ideal translational Motion Sensor - It is a motion sensor in mechanical translational systems.
6. Simulink-PS Converter - It Converts the Simulink input signal into a physical signal.
7. PS-Simulinlk Converter - It Converts physical signal into Simulink output signal.
8. Scope - It displays signals generated during simulation.
9. Electrical Reference - It is a reference conntection for electrical ground source.
10 . Mechanical Translational References - Reference connection for mechanical translational ports.
SIMULINK Model of Doorbell -
Conclusion -
Successfully completed the model of Doorbell using solenoid block.
Aim 2 - To use a thermistor as a temperature sensor of a heater & turn on or turn off the fan as per the objectives.
Objectives - 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
Explaination -
1. Switch - A Switch block passes through the first input or the third input signal based on the value of the second input. The second input is a control input. using PS-Simulink converter we convert output voltage signal from voltage sensor to simulink output signal and fed it into switch . we change the threshold value of switch to 0.012 so that switch only works for the given condition.
2. Resistor - Linear resistor in electrical systems.
3. Thermistor - Thermistor block represents an NTC thermistor using the B-parameter equation, controlled temperature source is directly connected to thermistor, the positive terminal of thermistor is connected to positive terminal of DC Voltage source and negative terminal of thermistor is connected to positive terminal of resistor.
4. DC voltage source - The DC Voltage Source block maintains a time-invariant (constant) voltage across its output terminals, independent of the current through the source. Voltage is 12V here.
5. Signal builder - The Signal Builder block allows you to create interchangeable groups of piecewise linear signal sources and use them in a model. You can quickly switch the signal groups into and out of a model to facilitate testing. In the Signal Builder window, create signals and define the output waveforms.
In this signal builder we are creating the following signals :
Temperature source: 20 °C from 0 to 10 seconds, 27 °C from 10 to 30 seconds, 23 °C from 30 to 50 seconds.
6. Simulink-PS-Converter - Converts the Simulink input signal to a Physical Signal, this is connected to signal builder which then connects to controlled temperature source.
7. Controlled temperature source - This block represents an ideal energy source in a thermal network that maintain a controlled temperature difference regardless of the heat flow rate. A signal builder block is connected to this block through a simulink-ps- converter.
8. PS-Simulink-Converter - Converts the input Physical Signal to a Simulink output signal.
9. Scope - Display signals generated during simulation.
10. DC Motor - This block represents the electrical and torque characteristics of a DC motor. we are using this block for representing fan.
11. Constant - The Constant block generates a real or complex constant value signal. Use this block to provide a constant signal input. We use constant block 1 for ON condition.
12. Controlled voltage source - The block represents an ideal voltage source that is powerful enough to maintain the specified voltage at its output regardless of the current passing through it. The signal from switch is converted to physical signal and given to controlled voltage source.
13. Ideal rotational motion sensor - This block measures angular velocity or angle in a mechanical rotational network. The sensor is ideal since it does not account for inertia, friction, delays, energy consumption, and so on. This block is connected parallel to dc motor to measure its properties.
14. Voltage sensor - The block represents an ideal voltage sensor, i.e., a device that converts voltage measured between any electrical connections into a physical signal proportional to the voltage. Connections + and - are conserving electrical ports through which the sensor is connected to the circuit. Connection V is a physical signal port that outputs voltage value. Voltage sensor is connected across resistor.
15. Solver configuration - Each physical network represented by a connected Simscape block diagram which requires solver settings information for simulation. The Solver Configuration block specifies the solver parameters that your model needs before you can begin simulation.
16. Electrical reference - The Electrical Reference block represents an electrical ground.
17. Thermal reference - The Thermal Reference block represents a thermal reference point, i.e., a point with an absolute zero temperature, with respect to which all the temperatures in the system are determined.
18. Mechanical rotational reference - This block represents a mechanical rotational reference point, i.e., a frame (ground). Use it to connect mechanical rotational ports that are rigidly affixed to the frame (ground).
19. Display - Displays the input values.
SIMULINK Model of Thermistor as a Temperature Sensor -
Here x-axis represents time (seconds) and y- axis represents temperature (kelvin).
Here x-axis represents time (seconds) and y- axis represents amplitude. When the amplitude is 1, then the switch is ON state and when the amplitude is 0, then the switch is OFF state. From this plot it is clear that the switch is in ON position between 10 and 30 seconds when the temperature is above 25 degree celcius.
Here x-axis represents time (seconds) and y- axis represents voltage. The reason for threshold value 0.012V in switch is because when we observe plot above we can see that in order to satisfy our on/off condition the value should be greater than 0.11.
Here x-axis represents time (seconds) and y- axis represents Angular Velocity of dc motor .
Conclusion -
Successfully completed the challenge of Thermister as a Temperature sensor for a given time period.
Google_Drive Link -
Link for Google Drive to access Files of the current challege - Google_Drive Link