Final Project: Design of an Electric Vehicle

Electric Vehicle design

System-level configuration

An electric vehicle consists of the following system

1. Drive cycle
2. PID controller
3. Battery (Energy source)
4. PWM average motor controller
5. DC Motor
6. Vehicle Dynamics

1. Drive cycle;

Description

The Drive Cycle Source block generates a standard or user-specified longitudinal drive cycle. The block output is the specified vehicle longitudinal speed, which you can use to:

• Predict the engine torque and fuel consumption that a vehicle requires to achieve desired speed and acceleration for a given gear shift reference.
• Produce realistic velocity and shift references for closed-loop acceleration and braking commands for vehicle control and plant models.
• Study, tune, and optimize vehicle control, system performance, and system robustness over multiple drivecycles.

• The time period for the drive cycle is 2474 sec

PID Controller

PID controller is an instrument used in industrial control applications to regulate temperature, flow, pressure, speed and other process variables. PID (proportional integral derivative) controllers use a control loop feedback mechanism to control process variables and are the most accurate and stable controller.

Here reference velocity and feedback velocity is compared and controlled.

PID controller act as the accelerator

PWM average motor controller

For all motor to run we need a motor controller which controlled the continues voltage and current level from the battery. here we have used PWM average model that takes input from duty cycle.

DC MOTOR

Here simple DC motor is used with the following parameters

Battery

A simple Li-ion battery is taken with the following parameters

Vehicle Dynamics

Vehicle dynamic subsystem block consists of the vehicle body block, 4 tire block and one simple gear block

1) Vehicle body

The vehicle body consists of various input to have a basic model

NR; Normal force

NF; Normal force front

H; Hub connection

V; Speed of the vehicle body

Beta; Grade angle

W; Wind velocity;

Here wind velocity is taken as1 m/s and the grade angle is kept 0 through out the cycle.

Vehicle body block parameter

2) Tire

The tire has 4 inputs which are connected to the vehicle body

A- Axles

S- Slip

H- Hub

N-Normal

3) Simple Gear

The vehicle body is connected to a simple gear system to transmit the power from the motor to the wheels. Block parameter for the gear is

All subsystem are connected to form complete Electric vehicle

Result

1)Duty cycle curve from the PID controller to the motor controller, based on this motor controller controls the motor voltage, in turn, it controls the motor rotational output

2) Distance covered by the vehicle is 17.7 km which is the actual distance of the FTP75 drive cycle

3) Feedback motor speed exactly traces reference speed of the drivecycle

Conclusion

The Electric vehicle model is simulated successfully and from this, we can conclude that the model is depended on many factors such as drive cycle, battery modelling, controller types , vehicle parameters etc.

These factors are responsible for the efficient output of the vehicle. These can be altered to make them even more efficient, more complex and efficient battery management systems and the motor controller can be used for future scope of the studies.