Final Project: Design of an Electric Vehicle

Electric vehicles have low running costs as they have fewer moving parts for maintenance and are also very environmentally friendly as they use little or no fossil fuels (petrol or diesel). While some EVs used lead-acid or nickel-metal hydride batteries, the standard for modern battery electric vehicles is now considered to be lithium-ion batteries a s they have greater longevity and are excellent at retaining energy, with a self-discharge rate of just 5% per month.

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What are the inner parts of an EV?

EVs have 90% fewer moving parts than an ICE (Internal Combustion Engine) car. Here's a breakdown of the parts that keep an EV moving:

• Electric Engine/Motor - Provides power to rotate the wheels. It can be DC/AC type, however, AC motors are more common.
• Inverter - Converts the electric current in the form of Direct Current (DC) into Alternating Current (AC)
• Drivetrain - EVs have a single-speed transmission that sends power from the motor to the wheels.
• Batteries - Store the electricity required to run an EV. The higher the kW of the battery, the higher the range.
• Charging - Plug into an outlet or EV charging point to charge your battery.

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Working principle of EV:

When the pedal of the car is pressed, then:

• The controller takes and regulates electrical energy from batteries and inverters
• With the controller set, the inverter then sends a certain amount of electrical energy to the motor (according to the depth of pressure on the pedal)
• An electric motor converts electrical energy into mechanical energy (rotation)
• Rotation of the motor rotor rotates the transmission so the wheels turn and then the car moves.

Blocks used to make EV model :

• Drive Cycle Source
• Longitudinal Driver
• Controlled Voltage Source
• Controlled PWM Voltage
• H- Bridge
• Current Sensor
• DC Motor
• Simple Gear
• 4 Tyres
• Vehicle Body
• Battery
• Controlled Current Source

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Model Design Of Electrical Vehicle :

Drive Cycle Source :

• Determining The Drive Cycle for the engine to run for given time
• Two Drive are,
• FTP75 and Wide Open Throttle (WOT),WORKSPACE VARIABLE

Longitudinal driver model:

It like a driver which is used to take the charge of driving its acceleration breaking commands as per the given conditions which is called as a reference.

VEL Ref is used to take the reference values for the driver to drive the vehicle.

Vel Fdbk is used to take the feedback from the output of the given data from the vehicle speed which is called as a velocity.

Accel Cmd is an output signal that gives as an input to the power control unit-controlled voltage source 1 which is connected to the PWM for the purpose of acceleration when the output is reduced to lower than the given reference value.

Decel Cmd is also an output signal that gives as an input to the power control unit-controlled voltage source 2 which is connected to the BRK for the purpose of breaking when the output is becoming higher than the given reference value.

Controlled Voltage Source :

The Controlled Voltage Source represents an ideal voltage source that is powerful enough to maintain the specified voltage at its output regardless of the current passing through it.

Controlled PWM Voltage :

It is used to give the Pulse Width Modulation signals to the H bridge circuit at the PWM terminal. The +ve reference terminal of the block is connecter to the controlled voltage source and -ve is connected to the electrical reference, the PWM is connected to the H bridge PWM as said above and REF is connected to the REF and REV terminals of the H bridge.

H - Bridge :

As the name indicates that the H symbol in the block is connected to the DC motor and the PWM, REF, REV, and BRK are used to control the block DC motor.

Current Sensor :

• The block represents an ideal current sensor, that is, a device that converts current measured in any electrical branch into a physical signal proportional to the current.

Electrical reference:

It is used to connect all the terminals of the negative signals and the reference values as the ground.

Ps-Simulink converter:

It is used to connect the line from the physical signal to Simulink which act as a converter.

DC Motor :

It is used to convert electrical energy to mechanical energy. In this electric vehicle model, we have used a type is permanent magnet DC motor. This motor can also act as a generator in the case of regenerative braking.

In this block, the motor's electrical side is represented with the blue color and the mechanical side is represented with green as well with the combination of shaft which is in the dotted line. here the motors +ve and -ve terminals are connected to the H-Bridge +ve and -ve terminals respectively with the electrical reference in the -ve side.

Mechanical rotational reference:

It is represented as a mechanical ground reference point that is as a frame part that is used to connect rotational parts to the ground.

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Vehicle Body :

• Connections B (base) and F (follower) are mechanical rotational conserving ports. Specify the relation between base and follower rotation directions with the Output shaft rotates parameter.

4 - Tyre :

Connection A is the mechanical rotational conserving port for the wheel axle

Connection N is a physical signal input port that applies the normal force acting on the tire

Connection S is a physical signal output port that reports the tire slip.

Vehicle Body :

• Connections V, NF, and NR are physical signal output ports for vehicle velocity and front and rear normal wheel forces, respectively. Wheel forces are considered positive if acting downwards.
• Connections W and beta are physical signal input ports corresponding to headwind speed and road inclination angle, respectively.

Battery :

In this subsystem we have used a battery block, a controlled current source block bus selector and Inport and outport blocks.

We can say that the battery is one of the main important parts or the block in the vehicle and model as well. By connecting this terminal to the controlled voltage source it supplies controlled signals to discharge and also charging in the regenerative type as well. The output signals of the battery are taken are SOC, current, and voltages.

Bus Selector :

The bus selector is used to block the output signals which are given as an input to that bus selector block

Here The left-side box shows the signals in the input bus, Use the Select button to select the output signals. The right-side box shows the selections, Use the Up, Down, or Remove buttons to reorder the selections.

powergui

It is used for the analysis and measurement of parameters like voltage, current, active power, reactive power like that.

Solver configuration:

It is placed in the power control unit for the mathematical values in the model solver settings at the simulation time

To get the results of this model we have to keep the stop time to 2474 sec or above because of the given drive cycle source with FTP (2474 seconds).

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RESULT......................................................................

It is the combination of both the drive cycle and the vehicle body velocity which is called as a feedback reference. Here the yellow represents the velocity and the blue is for drive cycle source. The both are looks in similar line different values. The changes of the values of this gives the acceleration and the deceleration values from the longitudinal driver model. Here if we observe that in given graph that in both values are changes in the changes in the accel and dec values but in the constant time they both are in same

• When the velocity and the drive cycle data can equally merged and the vehicle can control with respect the drive cycle FTP-75

SOC (%) :

It reduces based on the given input to the battery through the current signals

Voltage (V) :

Battery current:

if we observe here that accelerate goes up its current values increased and in it decelerates it value reduced respectively as above at the constant time that is from near value of 1400 to 2000 sec time it gets decreased slightly due to losses.