Week -2

AIM:To Make a Simulink model of Doorbell using solenoid block and also to Use a thermistor to sense the temperature of a heater & turn on or turn off the fan as per conditions by using simulink.

Objectives:the objective of first model is to make a model of doorbell using a solenoid block with the situation to create where the switch is closed for 2seconds and then released and also abserve the position of the plunger.

b.after to make a model to use thermistor to sense the temperature of a heater & turn on or turn off the fan as per the below conditions:

Temperature source:1)20 °C from 0 to 10 seconds

 2)27 °C from 10 to 30 seconds,

3)23 °C from 30 to 50 seconds

Fan conditions: ON if the temperature above 25 °C, OFF otherwise

EXPLANATION:

Solenoid:1.A solenoid is a basic term for a coil of wire that we use as an electromagnet. We also refer to the device that can convert electrical energy into mechanical energy as a solenoid.Actually it generates a magnetic field for creating linear motion from the electric current With the use of a magnetic field.

2.Solenoids are extremely useful and incredibly versatile. We can find them almost everywhere from doorbells to paintball guns and even in automated factory equipment. In doorbell, the audible sound generates because the metal piston strikes at a tone bar.

3.The magnetic field of solenoids is the force that moves the piston and this force receives the electric current when we ring the doorbell.

4.As the electric current passes through the solenoid’s coils, the creation of a magnetic field takes place. The magnitude’s strength is measured by the number of coils are featured by the solenoid.

5.The armature in a solenoid is movable: therefore, a voltage passes through the coils and the armature increases the flux linkage by its movement.

6.This happens due to the closing of the air gap between the two cores which are movable or the armature. They come with the spring so that the voltage is switched off to the solenoid, and then it gets back to its initial position.

7.the basic components used in the setup a simple door bell circiut are:

a.Battery

b.switch

c.solenoid

d.a bell with plunger.

EXPLANATION OF CODES:1.The doorbell circiut needs a solenoid,switch,battery and plunger.these components are taken from the simulink library.

2.it is a transitional part so we used a transitional motion sensor which is used to sense.and scope is used to defined the context of a model.The Trigger block Function visibility parameter is set to scoped.

3.the electrical and mechanical transitional block reference are used to represents a reference point, or frame, for all mechanical translational ports.

4. The Pulse Generator block generates square wave pulses at regular intervals.

5.The Solver Configuration block specifies the solver parameters that your model needs before you can begin simulation.

6.Simulink-PS Converter block converts the input Simulink signal into a physical signal. Use this block to connect Simulink sources or other Simulink blocks to the inputs of a Simscape physical network.

7.The PS-Simulink Converter block converts a physical signal into a Simulink output signal.Use this block to connect outputs of a Simscape physical network to Simulink scopes or other Simulink blocks.

MODEL:

pulse genertor block:The below diagram is the pulse genertor parameters the period is changes to 4sec along with a pulse width of 50% to get the 2seconds of pulse. which means the condition of the switch is closed in  2seconds so we created.

plot:from the below graph is represent the switch on and off position.when the x-axis is represent the 'Time' in seconds and the y-axis is represent the position of the plunger in mm.the graph represents the switch is closed for 2seconds.the value will changes with respect to time.due to recoil of the spring the value gets change and the process moves on.

Thermistor:1.A Thermistor is a type of resistor,whose resistance is strongly dependent on temperature, more so than in standard resistors. The word is a combination of thermal and resistor. Thermistors are widely used as inrush current limiters, temperature sensors (negative temperature coefficient or NTC type typically), self-resetting overcurrent protectors, and self-regulating heating elements (positive temperature coefficient or PTC type typically). With NTC thermistors, resistance decreases as temperature rises; usually due to an increase in conduction electrons bumped up by thermal agitation from the valence band. An NTC is commonly used as a temperature sensor, or in series with a circuit as an inrush current limiter.

2.As an inrush current limiter device in power supply circuits, they present a higher resistance initially, which prevents large currents from flowing at turn-on, and then heat up and become much lower resistance to allow higher current flow during normal operation. These thermistors are usually much larger than measuring type thermistors, and are purposely designed for this application.

The basic components used to setup a simple cooling fan circuits are:

1.Battery

2.Thermistor

3.Fan

4.Transistor

5.Resistor

Explanation:1.The simple cooling fan model is created by using the blocks of the thermistor, battery,reistor,signal builder,votage sensor ,control voltage source,dc motor,idel rotional sensor and controlled temperature source. 

2.the component blocks of the cooling fan are connected.

3.when simulink block connected with physical network by using the simulink-ps converter.otherwise connect directly.

4.The PS-Simulink Converter block converts a physical signal into a Simulink output signal.Use this block to connect outputs of a Simscape physical network to Simulink scopes or other Simulink blocks.

5.The Solver Configuration block specifies the solver parameters that your model needs before you can begin simulation.

6.The electrical and mechanical transitional block reference are used to represents a reference point, or frame, for all mechanical translational ports.

7.The constant is used to switch ON and OFF position.Temperature source: 20 °C from 0 to 10 seconds, 27 °C from 10 to 30 seconds, 23 °C from 30 to 50 seconds.

8.Along with the Fan conditions is ON if the temperature above 25 °C, otherwise  OFF.

9.Three port switch is used.

10.The signal builder block is used to quickly develop and modify test input data that you want to incorporate with your model.

11.the voltage sensor is used sense the voltage across them and the control voltage source is used to assigned the motor to run with our given condition of 25degree celsius to switch on fan.

12.finally all the connections are connected. the current pass through the thermistor through the resistor the voltage should measured with voltage meter and the it will be controlled with given condition.once the temperature is reached the sensor indicates and it will switch is on otherwise the switch get closes. 

Model:

PLOT:The below graph is represent the position of the switch.

conclusion:The given model is created successfully along with the given conditions by using the simulink