Final Project: Design of an Electric Vehicle

OBJECTIVE:

The main objective of this project to model an electric vehicle utilising diffrent blocks of Simulink and conclude the performance of vehicle.

MODEL PARAMETERS:

Fig 1 Electric vehicle Blockset

Fig 1 Shows complete blockset and connection of an electric vehicle. It consists of FTP75 Drive source connected to Driver block. Driver block gets feedback velocity from Vehicle blockset and gives accelation and brake command as input to DC motor blockset. DC Motor is connected to Vehicle block and drives the vehicle. Vehicle velocity is taken as an input to calculate the Distance covered using FTP75 Cycle and also Velocity graph will be analysed using Scope block.

1. Drive cycle block

We had used FTP75 drive cycle block to give as a reference velocity source to our Driver block. Using scope we have obtained the velocity plot curve as shown below in Fig 2 for our drive cycle.

Fig 2 FTP75 Drive cycle

2. Longitudinal driver block

Fig 3 Longidudinal Driver

As shown in fig 3, various inputs are given to the Longitudinal block.

Vel ref- from Drive cycle

Vel Fdbk- from Vehicle block

Grade- grade angle is given as 0

Accleration command and Decelaration command are given by this block to DC Motor block using PI controller.

Fig 4 Accelaration command

3. DC Motor Block:

Fig 5 DC Motor Block

As seen in Fig , DC motor block diagram has been shown. It consists of PWM H bridgeController with controlled PWM Voltage input, DC Motor connctected with reference mechanical rotor(in green).

It gets input 1(decelaration) and Input 2 (accelaration) command from longitudal driver block and these inputs goes to PWM controller through controlled voltage source as these commands needs to work between voltage limit of controller. We are using internally powered PWM H bridge controller whose parameters are given in FIg 6 and Fig 7 below.

Fig 6 PWM H Bridge Block parameters

Fig 7 PWM H Bridge Block simulation mode and load assumptions

From above figures 6 and 7, we can summarize that an internally powered H bridge controller is used with Averaged type simulation mode having active regenerative braking. An internal power source of 330 V is used having 0.1 ohms resistance.

From PWM controller, power is supplied directly to a DC Motor, whose properties are shown in Fig 8 below :

Fig 8 DC Motor parameters

A permanent magnet field type DC Motor is used having 0.01 armature inductance. Its no load speed is taken as 7000 RPM and Rated speed is taken as 5000 RPM. Rated DC supply is taken same as PWM H bridge i.e. 330 V.

Its rated load is taken as 75 KW.

4. Vehicle Blockset

Fig 9 Vehicle Blockset

DC motor shaft is now connected with Gear box, whose gear ratio is taken as 4. It then connects the chassis with inertial load placed on its axle as 0.01 kg*m^2.

We are using rear wheel drive, thus rear wheels are connected using axle and takes power from DC Motor through Gear box. Front wheels are also connected using axles and hubs are connected to the Vehicle body block. Tire parameters are shown in Fig 10 below.

Fig 10 Tire parameters

Load dependent tire coefficients are taken using magic formula to automatically derive different coefficients of tyre.

Fig 11 Vehicle body parameters

Fig 11 shows different parameters used for Vehicle body or chassis such as mass =800kg and different center of gravities from vehicle designing.

OUTPUT :

1. VELOCITY

Fig 12 Vehicle velocity output

As observed from Fig 12, vehicle velocity(yellow graph) matches with the initial reference graph plot of FTP75 driving cycle. Thus it can be concluded that vehicle control is achieved suffiently using various parameters used in PWM controller ,DC motor, Vehicle block and overall EV block.

2. DISTANCE

Fig 13 Distance vs Time plot

Total Distance covered by the vehicle is plotted along the time using distance calculator blockset connected with vehicle block as seen in Fig 1. A distance of around 5.2 kms is travelled.

3. STATE OF CHARGE

State of charge is the measure of how much charge is used by running a certain drive cycle. It is calculated by integrating SOC calculator block with DC Motor as shown in Fig 14.

FIG 14 SOC Block

FIG 15 SOC Output

As seen from Fig 15, we can say that after completion of FTP75 cycle, a 75 hr A capacity battery's SOC will fall to nearly 62% i.e. around 28% of the charge will be utilized.

CONCLUSION:

An electric vehicle has been designed and analyzed effectively using Simulink and outputs are describing the performance of the vehicle efficiently.

ACKNOWLEDGEMENT:

I would like to acknowledge the whole team of Skill lync for providing me this platform, where I am able to gain experience and knowledge in Hybrid and electric Vehicle design. I would especially like to thanks my support engineer cum mentor Sathya mam for always helping me throughout my project.