Final Project: Design of an Electric Vehicle
A MATLAB model of an electric car has been developed using battery and a DC motor along with other elements from Simulink library and enclosed herewith vide New_El_Car.The various blocks being used include the followings:
1.Drive Cycle Source:1
2.Longitudinal Driver:1
3.Power Converter Subsystem
4.Battery:1
5.Controlled Current Source:1
6.SoC Estimation Unit
7.Curent Sensor:1
8.Permanent Magnet DC Motor:1
9.Mechanical Subsystem
10.Scope:3 nos
11.Integrator:1
12.Constant:1
13.Product Unit:1
14.Display Unit:1
Power Converter Subsystem comprises of a Controlled PWM Voltage,a H-Bridge,two Controlled Voltage Sources, a Solver Configuration and a Simulink-PS Converter.
SoC Estimation Unit is made of an Inport,a Rate Transition Unit,a Gain Unit,a Discrete Integrator,a Sum Unit,a Constant and an Output Unit.
The Mechanical Subsystem comprises of a Vehicle Body,four Tyres, a Simple Gear (ratio:3.7),a PMC port,an Output Unit, two PS Constants(one for wind velocity and one for inclination) and an Inertia Unit.
As far as parameterization is concerned the Battery AmpereHour has been taken as 80 and Battery Nominal Voltage has been taken as 330V.The Power rating of the DC motor is taken to be 75 kW,rated speed as 5000 rpm,no-load speed as 7000 rpm and supply voltage 330 V DC.For all of the other blocks mostly default settings have been used.
Simulation of the model was run successfully.The following observations have been made:
From the Speed Graph we find that the EV model which has been designed traced the Drive Cycle very closely.The Vehicle attains speed value of 30 in about 7 seconds and speed drops to 5 after 20 seconds.The Drive Cycle speed is 100 in 5 seconds and this becomes zero in 20 seconds onward.So the conclusion is only when the Drive Cycle speed suddenly drops to zero the model takes time to catch up.On other occasions it traces the Drive Cycle closely.
Looking at the SoC graph it is seen that the value is reduced slightly from initial level(100%).Also sudden spikes are observed during the simulation run.The spikes represent regenerative braking which is a situation when the motor acts as a generator and the current direction is back to the battery.
It is seen from the Current graph that current rises from (-)130 to zero in about 8.4 seconds and remains steady thereafter.Offset is 20 and Time Period is 30.
The output graphs from the three Scope Units can be visualized after running the simulation and separate screenshots can be taken when required.
The display unit shows the total distance travelled by the vehicle.The maximum speed that can be attained by the vehicle is limited by the capacity/rating of the Permanent Magnet type DC motor.This can be increased by increasing the motor power and voltage.