Week -2

1. Simulink model of Doorbell using solenoid block

Aim:

To make a Simulink model of doorbell using solenoid block with the condition of creating a situation where the switch is closed for 2 seconds and then released.

Objective:

To create a Simulink model of the doorbell using solenoid block and operate the model with the input and plot the result.

Blocks used in this model:

Solenoid Block - This solenoid block represents the electrical characteristics and mechanical fore for the solenoid. This block has two inputs, Port R and Port C.

Ideal Translational Motion Sensor - It is used to observe the physical movement of the plunger

Solver Configuration - This block monitors each physical network represented by a connected Simscape block diagram. Every Simscape model needs a solver configuration block for simulation.

Pulse generator - The pulse generator block generates square wave pulses at desired intervals. We can vary the parameters of the pulse generator such as amplitude, pulse width, period, and phase delay.

Switch - The switch performs simple ON and Off operations, the physical signal is greater than the specified value.

Scope - The scope block generates output as waveforms represented as graphs.

Simulink Model:

Pulse Input:

The pulse input has a time period given as per the condition 2 Sec. In this case, the pulse generator is closed for two seconds and releaded. The pulse generator gives the pulse signal amplitude of 1 with no phase delay.

Output:

Plunger observation:

When the switch is closed the solenoid block receives electrical power from the batter. Then plunger moves from Port R to Port C to hit the bell and produce sound. Here the ideal translational motion sensor observes the plunger and sends a physical signal. Then the physical signal is converted to a Simulink signal and displayed in the scope. The above graph shows the condition of the plunger should be ON for 2 seconds is successfully achieved.

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

Aim:

To sense the temperate of a heater and turn ON or turn OFF the fan by using a thermistor with the Fan condition: ON if the temperature is above 25 °C, OFF otherwise.

Objective:

To sense the temperature of a heater and turn On or turn OFF the fan by using a thermistor with the fan conditions, plot the graph with the temperature source.

Blocks used in the model:

Signal Builder - The Signal Builder block is used to create linear signal sources and define output waveforms.

Controlled Temperature Source - The controlled Temperature Source block represents ideal thermal energy that is powerful and maintains a specified temperature difference across the power source. It has two thermal ports A and B.

Thermistor - A thermistor is a type of resistor that varies the output with the heat observed.

Resistor - The resistor is used to resist the flow of current.

Voltage Sensor - The voltage Sensor block converts the voltage measured between two points of an electrical circuit into a physical signal.

Explanation:

The signal builder is given with the input signal with the condition of the temperature source, connected to the controlled temperature source.

Inputs:

The signal builder is given with the input from temperature source conditions

Point 1 - At time 0 Sec the temperature is 293K

Point2 - At time 10 Sec the temperature is 293K

Point 3 - At time 10 Sec the temperature is 300K

Point 4 - At time 30 Sec the temperature is 300K

Point 5 - At time 30 Sec the temperature is 296K

Point 6 - At time 50 Sec the temperature is 296K

Then the input from the controlled temperature source is given to the thermistor. Then thermistor is connected with a resistor. The positive of the resistor is connected to the negative of the thermistor. Then Voltage sensor is connected in parallel with the resistor. The battery is used as a power source for the model and the positive terminal of the battery is connected to the positive of the thermistor. The output terminal of the voltage sensor is connected with switch. The switch decides the output and sends the output to the scope.

Output:

From the above graph, the temperature of the thermistor is 293K so, the fan is OFF for 0-10 seconds. Then temperature increases to 300K after 10 seconds so, the fan is ON because the fan exceeds the threshold value. Then, the temperature goes to 296K after 30 seconds when the fan is OFF. The threshold is around 298K. So, the fan is ON if the temperature exceeds 298K and turns OFF when the temperature is below 298K. From the above results, the given conditions have been achieved.