Week -2

Question-01

SAYIRAAM KS

Simulink Model for a Doorbell using Solenoid Block

AIM:

To make a Simulink Model of Doorbell using Solenoid Block.

SOLENOID:

A Solenoid is a type of electromagnet, the purpose of which is to generate a controlled magnetic field through a coil wound into a tightly packed helix. The coil can be arranged to produce a uniform magnetic field in a volume of space when a current is pass through it. The term solenoid was coined in1823 by Andre-Marie Ampere to designate a helical coil. In Engineering the term may also refer to variety of transducer device that convert energy into linear motion. The term is also often use to refer to a solenoid valve, an integrated device containing an electromechanical solenoid which actuate either a pneumatic value or hydraulic valve, or a solenoid switch, which is specific type of Relay that internally uses an electromagnetic solenoid to operate an electric switch for example an automobile starter solenoid or linear solenoid, solenoid bolts, a type of electromechanical locking mechanism, also exist. In electromagnetic technology, a solenoid is an actuator assembly with a sliding ferromagnetic plunger inside the coil. Without power, the plunger extends for part of its length outside the coil; applying power pulls the plunger into the coil. Electromagnet with the fix core is not considered solenoids.

Basic Component used to generate a simple Doorbell circuit is:

GIVEN CONDITION: IN the arrangement, when the switch is closed the electromagnet receives electrical power from the Battery and pulls the metal arm to hit the bell producing sound by creating a situation where the switch is closed for 2 secs and then released.

Components used

Pulse Generator:

The Pulse Generator block generates square wave pulses at regular intervals. The block waveform parameters, Amplitude, Pulse Width, Period, and Phase delay, determine the shape of the output waveform. The following diagram shows how each parameter affects the waveform.

Battery:

In Battery positive terminal is connected with switch and negative terminal is connected to “Electric Reference”.

Switch:

The switch Block model a switch is controlled by an external physical signal.

Solenoid Block:

Solenoid Block is connected with Switch and Battery and electrical circuit will be formed.

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 as from 0 to 10. To show the direction in which the solenoid acts the block icon changes dynamically based on value of the Motion direction under excitation parameter. The Port ‘C’ is connected with Mechanical Translation reference.

Ideal Translation Motion Sensor Block:

Ideal Translation Motion Sensor Block is connected with Solenoid Block ‘R’ to observe the Physical movement of the Plunger.

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 = vR – vC, where vR, vC are the absolute velocities at ports R and C, respectively. Port C is connected with Mechanical translational reference.

Scope:

Scope is connected with Ideal Translation Motion Sensor to get the output. The real-time Scope block acquires data in chunks of size Number of samples from the real-time application that is executing on the target computer.

PS-Simulink Converter:

The PS-Simulink Converter block converts a physical signal into a Simulink output signal. Use this block to connect outputs of a Physical Network diagram to Simulink scopes or other Simulink blocks.

Simulink-Ps Converter:

This Block convert simulink signals into physical signal for operational use in Model.

Electrical Reference Block:

The Electrical Reference block represents an electrical ground. Electrical conserving ports of all the blocks that are directly connected to ground must be connected to an Electrical Reference block. A model with electrical elements must contain at least one Electrical Reference block.

Mechanical Translation Reference Block:

The Mechanical Rotational Reference block represents a reference point, or frame, for all mechanical rotational ports. All rotational ports that are rigidly clamped to the frame (ground) must be connected to a Mechanical Rotational Reference block.

Solver Configuration:

Each physical network represented by a connected Simscape block diagram requires solver settings information for simulation. The Solver Configuration block specifies the solver parameters that your model needs before you can begin simulation.

OBJECTIVES:

For Doorbell- Create a situation where the switch is closed for 2 sec and then released. Observe the physical movement of the plunger.

SIMULINK MODEL:

Model Explanation:

A pulse generator is given as input with the following specifications. The condition was that the bell is engaged for 2 s and then released. Same was implemented by giving period as 4 seconds and pulse width as 50% of 4 seconds, i.e, 2 seconds. Phase delay was given as 2 seconds, so the simulation starts from the unengaged condition of switch.

The signal from the pulse generator was converted using a Simulink-PS converter and is given as the input to the switch. A Solenoid is introduced and battery is connected to it. The voltage of the battery connected was made as the same as that of the rated voltage of the solenoid. The Switch is also connected to the same circuit. The position of solenoid plunger is measured using an ideal translational motion sensor connected to the circuit. Initial position was set to 5mm in translational motion sensor. Both mechanical and electrical references were connected to the respective circuits. The output from the ideal translational motion sensor is converted using a PS-Simulink converter and is given to the scope to display the results. A scope was also connected to the input to visualize its behaviour. The spring constant and damping parameters of the solenoid block was altered to obtain desired graph

Input signal

Output signal

Question-02

SAYIRAAM KS

Simulink model of Thermistor to sense the temperature of a heater & trigger a fan.

Aim:

Create a simulink model of thermistor to sense the temperature of a heater & turn on or turn off the fan.

Conditions:

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.

Blocks used in model:

• Signal builder
• Controlled Temperature Source
• Thermistor
• Resistor
• Voltage sensor
• Battery
• Switch
• Lamp
• Scope
• Display
• PS-Simulink Converter
• Simulink-PS Converter
• Solver Configuration

Simulink Model:

Model Explanation:

A signal builder is given as input to the thermistor through a controlled temperature source. The definition of Signal builder block is given below.

The conditions of the temperature source is defined inside the above window. The sample time was taken as 10s and the whole simulation time was taken as 50s.

Battery and a resistor is connected in the thermistor circuit. A voltage sensor was given across this resistor to measure the voltage change during different temperature inputs. The resistance of this resistor can be set to any value, but it should not be changed once the threshold voltage is found. The threshold temperature was given as 25 degree Celsius and the corresponding voltage over the resistor was found out, through a display connected to the voltage sensor. At this time the Signal builder was given only one value, i.e, 25 degree Celsius or 298 K. The output from the voltage was also given into a switch which is linked to a lamp which displays different colours based on the logical conditions. The lamp colour was set to red if the temperature was below 298K and to green when the temperature is above 298K.

Results:

When the temperature is below 298K

When the temperature is above 298K

Graph

Graph

.