#5 DC Machine Characteristics

1. Implement DC machine torque speed characteristics equations in MATLAB script file. It asks user to input data and plots speed (RPM) versus torque (Nm). Submit the .m file for evaluation and attach the screenshots of all the required plots.
2. How can you distinguish between power cables and signal cables and also prepare a table where these cables are used in the wiring of an electric vehicle?
3. What voltage levels are considered as high & low for a battery pack of electric vehicles?

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1.Implement DC machine torque speed characteristics equations in MATLAB script file. It asks user to input data and plots speed (RPM) versus torque (Nm). Submit the .m file for evaluation and attach the screenshots of all the required plots.

close all
clc
motor_speed = linspace(0,250,75);
%inputs
speed_constant=input('enter values of motor speed_constant: ');
V=input('enter the value of total battery voltage supply: ');
ra=input('enter the value of armature resistance: ');
back_emf=1;
%formula to calaculate motor constant
k_fi = ((back_emf)*60)./((speed_constant)*6.28);
%formula to calculate Torque
T=(((V*k_fi)/ra)- ((k_fi^2)/ra).*motor_speed);
%formula to calculate motor speed
motor_speed=motor_speed *(60/6.28);
%Total current (I=V/R)
Ia=(V-back_emf)/ra;
%max torque for total current
Tmax=k_fi*Ia;
plot( motor_speed,T,'LineWidth',3 );
title('speed Vs Torque');
ylabel('speed (rpm)');
xlabel('Torque(Nm)');
axis([0 2000 0 250]);

The given input values are

The results are

from the plot, the speed torque characteristics is a straight line with negative slope.

when the speed increases, the toque value decreases which means speed and torque is inversely proportional to each other.

2.How can you distinguish between power cables and signal cables and also prepare a table where these cables are used in the wiring of an electric vehicle?

Power cables:

Power cables are basically electrical conductors that are held together in order to transmit electric power on a large scale. It has many industrial applications which makes the wires a popular choice to be used in ships, hospitals, industrial areas and many others.

Signal Cables:

Signal cable is used in data transmission applications that demand superior signal protection. These applications require some of the smallest, most flexible, and highly-screened cables on the market. Signal cables are used in a multitude of industries and can be found in everything from computers, medical equipment, and appliances.

The main difference between power and control cables is that control cables are plain annealed conductors whereas the power cables are conductors of copper and aluminum. Where power cables are made for transmitting electricity, the control cables act as controlling agents in the different process automation fields.

A simple example for understanding is, In our mobile phones the wires used in the charger is a power cable and the wire used for earphones is a signal cable.

Incase of the electric vehicle, the cables used to connect engine, motor and battery are power cables because it has to transmit the required propulsion power whereas the signal cables are used in test and measurement applications.

3.What voltage levels are considered as high & low for a battery pack of electric vehicles?

An electric vehicle battery is often composed of many hundreds of small, individual cells arranged in a series/parallel configuration to achieve the desired voltage and capacity in the final pack. A common pack is composed of blocks of 18-30 parallel cells in series to achieve a desired voltage. For example, a 400V nominal pack will often have around 96 series blocks (as in the Tesla Model 3).

Common nominal pack voltages in current vehicles range from 100V-200V for hybrid/plug-in hybrid vehicles and 400V to 800V and higher for electric-only vehicles.

Filname	Size	Action
Torquea…achine.m	723 B