Final Project: Design of an Electric Vehicle

• H this stands for hub and is used to connects the hubs of the wheels to the main body of the vehicle.
• V physical signal output port which stands for velocity and is used the output the velocity of the vehicle.
• W physical signal port and allow us to model a wind velocity that acts against the vehicle.
• NR physical signal output port to connect to the rear wheels.
• NF physical signal output port to connect the front wheels of the vehicle.
• Beta physical signal input port which allow the vehicle to undergo an inclination of hill climbing force. 

All the parameters are the same which we taken in this model as per mentioned above.

Tire block:- 

• Connection A is the mechanical rotational conserving port of the wheel axle.
• Connection H is the mechanical rotational conserving port of the wheel hub through which the Thurst developed. 
• Connection N is the physical signal input port that applies the normal force acting on the tire.
• Connection S is the physical sinal output port that reports the tire slip.

Simple gear:-

This block models a gear system with fixed gear ratio with no intertia effects. However we can modify the messing of the gear teeth, Here the follower to base teeth ratio has been set to 2 and the output shaft rotates in the same direction as the input shaft. 

These blocks are forming a subsystem which serves as a part of the whole vehicle. Four tires are connected where the right two tires are front wheel and the left two tires are rear wheel. They are interconnected with the vehicle by the Hub port and the axle are also connected accordingly. Here we have connected the rear axle with the gear as we want the model to be a rear wheel drive vehicle.  

Vehicle Body Subsystem:-

The above block is forming a subsystem which serves as a part of the whole vehicle. Four tires are connected where the right two tires are the rear wheels and left two tires are the front wheels. They are interconnected to the hub of the vehicle body block. And their respective axles are connected accordingly. We here have connected the rear axle with the gear as we want the model to be a rear wheel drive vehicle. Here the wind velocity part and hill climbing angle ports are connected to physical constant blocks which is kept as zero. 

Motor & Controller Subsystem:- 

DC motor:- 

For the EV model, i have selected to use a DC motor block because DC motors are easy to model a very few parameters to run for a particular application. There are two sides of the block, The machanical side is on the right and the electrical side is on the left. Mechanical side has two ports C and R, C stands for casing and is the stable part and R is the rotor which produce a Torque. The electrical side has a positive and negative side for the voltages to be applied. If positive voltage is applied to the motor block from the positive to the negative terminal then a positive torque will act from C to R port.  The diretion of the port can be changed by changing the sign of the back emf of the torque constant. Here i have connected the C port to the mechanical rotational reference because it will be stationary. The R port is connected to the gear in the vehicle body block. 

H-Bridge:- 

This is the power converter which is needed to provide power of the correct form and magnitude from one component to other. In case of EV,s a power converter is needed to provide a DC voltage from the battery of the EV to the DC motor, so that it can function properly at the required parameters. Here i have used an H-bridge motor drive as my power converter. The left side is for controlling the voltage signal stand the right side terminals to provide the controlled voltage to the DC motor the left side ports are.

• PWM-Pulse width modulation
• REF-Reference
• REV-Reverse
• BRL-Brake

Controlled PWM voltage:- 

Next i have used a controlled PWM voltage to provide a controlled pulse width modulated voltage to the H-bridge block. The pulse of voltage created by this block are dependent on the duty cycle which is in that ratio of the time that the switch is ON to the time taken for one cycle. The duty cycle formula is given by 

Duty cycle:- Ton/(Ton+Toff)

Ton/Tcyc, Where Tcyc= time taken for one cycle

Controlled Voltage Source:- 

This blocks provides the necessary voltage that is powerfull enough to maintain the voltage at the output regardless of the current that passes through it. In this subsystem  control voltage blocks have been used. One block is used for acceleration and the other to provide the voltage for deacceleration. 

Electrical reference block is used to create grounding effect for electrical circuit. In my model, we have used it in 2 parts. First one is electrical ground between controlled voltage source, Controlled PWM voltage, H-Bridge blocks. The second is for the battery system which will be modelled afterwards.

Solver configuration block is used to solve any necessary equation in a model. I have used them in the connection to the REV port of the H-Bridge block. 

Motor controller subsystem:- 

Battery:- 

The battery will be the energy store of the EV and will contain the electrical energy in DC form and provide this energy to operate. 

Nominal voltage has been set to 12 volts, internal resistance has been set to 2 ohms and an infinite charging capacity.

Controlled current source:- 

Similar to the voltage source this block provides the ideal current that is powerfull enough to manintain the specified current regardless of the voltage across it. 

SOC subsystem:- 

To measure the state of charge of the battery, a sub system was created of various blocks. The first block is integrator block used to handle data transfer and integrat the value of the current signal with respect to time and next is the Gain block is used in order to multiplier divide the signal coming from integrator block. This block will divide the current signal with the ampere rating of battery which is 150(AH)*3600(secs in hour). Assuming the battery is always fully charged, i have added the constant block with a value of 1 representing 100% . Next a sum block is used to perform addition and substraction operation of these blocks are made into a subsystem called SOC estimate. A scope block is used at the junction at the PS-Simulink converter block to plot the output signal of the current from the battery. 

Battery Subsystem:- 

Speed measurement:- 

In order to measure the speed i have modified the scope blck to have two input ports where one port takes the output velocity signal from the vehicle sub system block and other part takes the output signal from the drive cycle to the reference velocity port on the longitudinal driver block. This has been done to compare the two speeds and check weather they overlap and achieve the same speed.

Mathmatical block and scope block is used to measure the distance travelled by the vehicle. firstly use integrator to integrate the velocity signal that is output of the velocity sub system. Divident block along with constant block having some value of 3600 used to divide the intergrated speed. This will give us distance travelled in Km. 

Longitudinal driver block:- 

The longitudinal driver block is used for giving normalized acceleration and deacceleration commands to a controoler based two sets of data. The first data is the reference velocity and the second data is the feedback velocity. The reference velocity data coming from drive cycle source and is comapred to the feedback velocity data coming from the vehicle body.If the reference velocity is greater than the feedback velocity. An acceleration command will be given as an output to the controlled voltage source. If the reference velocity is lesser than the feedback velocity, a deacceleration command is given as the output to another controlled voltage source. For the output acceleration and deacceleration command i have used simulink-PS converter block. In this case the input signal is velocity data and this is logic data which have to be converted to a voltage signal the parts in this block one. 

• velref:- This stands for the reference velocity and it is the velociy data provided from a drive cycle source.
• Velfdbl:- This stands for feedback velocity and it is coming from the vehicle's body velocity part.
• Grade:- This part provides a grade or inclination angle on which the vehicle is travelling in degrees.
• Info:- This part is for the bus signal which consist of block calculation.
• Accelcmd:- This port provides the acceleration command to a controlled voltage source.
• Deacclcmd:- This port provides the deacceleration command to another voltage source.

 Driver cycle:- 

A drive cycle is a data set that contains velocity and time data for the purpose of modeliing the motion of the vehicle. it is a plot of the vehicle against the time and it is made to resemble typical during condition that a consumer may experience themselves. 

Result:- 

SOC:-

Battery current:- 

Conclusion:- The EV model has been created with necessary block components using the simulink softwar and the model have been simulated for an industrial drive cycle. Results are the velocity of te vehicle, current flowing from the battery and state of charge as well as the dsitance travelled in simulation time. 

The EV model was able to follow the command given by reference velocities from the drive cycle data. The distance travelled by my EV was about 16Km. The SOC of the battery is about 99%. According to this drive cycle i have also enabled regenrative mode too which is helpful for the battery capacity. Regenrative behaviour can bee see in the current scope as well. 

Model link-:

https://drive.google.com/file/d/1uWXLSA-m0N50RDY7gTm23fMQ7Hc2GX0F/view?usp=sharing