Project-1: Modelling an electric Car with Li-ion battery
Create a MATLAB model of electric car which uses lithium ion battery and suitable
motor. Choose suitable blocks from Simscape or Powertrain block set. Implement the
vehicle speed control using PI controller and generate brake and accelerator
commands. Avoid using readymade driver block for speed control.
Prepare a report about your model including following:
Objectives, System level configurations, Model parameters, Results, Conclusion.
(Note- The simulink model file should be compulsorily attached)
Your Answers
AIM:- Modelling an Electric Car with a Lithium-ion battery
INTRODUCTION:-
The electric vehicle is a vehicle, which uses one or more electric
motors for propulsion. Depending on the type of the vehicle motion may be provided by
rotary motor or by a linear motor (in the tracked vehicle). The electricity stored in
battery-powered by electric motor & battery can be charged by plugging it in the grid,
like our phone.
According to the degree of electricity used, an electric vehicle is divided into 3
categories-BEV, PHEV & HEV.
Battery Electric Vehicles (BEV)
BEVs are fully electric vehicles with rechargeable batteries with no engine. It stares
power in battery pack & this power is used to run the vehicle & other peripherals BEVs
are charged by electricity from external source BEVS don't emit any hazardous
emissions. Some most famous examples of these types of cars are BMW 13, Tesla
Model, 3. Kia Soul Toyota Rav4 etc.
Plug-In Hybrid Electric Vehicles (PHEV)
These types of vehicles are propelled by motor and gasoline engine Battery is charged
with regenerative braking & it can be charged with external source PHEVS can go from
10-40 miles before the assistance of engine Examples PHEVs-Chevy Volt. Audi A3 E-
Tron BMW i8. Toyota Prius etc
Hybrid Electric Vehicle (HEVs)
HEVS are powered with both gasoline & electricity. The battery can be charged with
regenerative power only. The motor supplies power from starting, the engine takes care
of high speed & heavy load. Controller used to ensure the best economy, HEVs are-
Honda Civic Hybrid, Toyota Prius Hybrid, Toyota Camry Hybrid.
OBJECTIVES:
• Create a MATLAB model of an electric car that uses a lithium-ion battery and a
suitable motor. Choose sustainable blocks from Simscape or Powertrain block set
• Implement the vehicle speed control using Pi controller and generate brake and
accelerator commands Avoid using readymade driver black for speed control
Prepare a report about your model including the following:
# Objectives
# System-level configurations
# Model parameters
# Results
# Conclusion.
CASE-STUDY
MATLAB Model of Electric Car which uses Li-ion Battery and Suitable Motor:
Electric Vehicle model Explanation
@ The electric vehicle model is represented by using MATLAB/Simulink. This model is
a complete representation of an electric vehicle that is built using Powertrain Blockset.
@ This model has vehicle dynamics & electrical system, the vehicle dynamics contains
subsystem relates to the vehicle body & tires whereas the electrical system contains a
subsystem related to the motor & battery pack This subsystem contains various other
components which we will understand further
PROCEDURE
1 Vehicle Dynamics Subsystem Model
The vehicle dynamics is nothing but the study of the vehicle motion & how the vehicle
behaves in motion
The vehicle Dynamics consist of 2 main subsystems.
1.1 Wheels & Brakes
1.2 Vehicle Body
1.1 Wheels & Brakes
• The wheels used in this vehicle are longitudinal wheels that have brakes of disk type.
• Disk brakes have great stopping power and cause less wear & tear & provide precise
braking. This block implements the longitudinal behaviour of the actual wheels.
• This vehicle is rear wheeled drive hence the axle torque is connected to the rear of the
wheels & the axle of the front wheel is grounded.
• The longitudinal forces of the tires are set to magic formula constant. A magic formula
is a separate form of a characteristic function of stiffness, shape, peak (BCDE). &
curvature
The magic formula is given as (F=f (k, F)=FDsin(C tan-1[{B-E[B-tan-1(B)]}])
The brake input command for the front & rear wheels is connected commonly as one
input port. Omega is the angular velocity of the wheels in the y-axis hence this form is
considered as torque input to the wheels.
Parameters for wheels as showing below.
1.2 Vehicle Body
# In this model Vehicle Body (1DOF) longitudinal block is implemented. This block helps
us to determine the vehicle inertia & drag load.
# There are mainly 2 forces acting on the axle of the wheels: longitudinal forces &
normal forces. These forces act on the rear & front of the wheels, the longitudinal forces
on the rear & front is given by (FwF, FwR).
# Whereas the normal forces are given by (FzF, FzR) These forces are connected to
the respective axle of the wheels.
# The vehicle body consists of Grade & Wind input ports which can be used to simulate
Slope & Wind Drag but this port is been grounded to minimize the complexity of the
model
# The X-Dot output port is a longitudinal force in the x-axis which acts as the
velocity/speed of the vehicle in m/s.
2. Torque Differential Subsystem Model
• The torque differential block is connected between the motor shaft & axle of the
wheels. The block consists of an open the and differential block & torsional compliance
• The open differential block is basically a set of Planetary gear systems, it matches the
drive shaft gear to the crown gear and couples the transmission driveshaft to the wheel
axle.
• The block uses a coordinate system that produces a positive tire & wheel motion.
• Input for the open differential drive shaft torque which accepts input from the motor
drive shaft & axle torque which are connected to the axle of the wheels
• On the other side torsional compliance is basically a spring-damper which is a shaft
that connects between the open differential & axle wheels.
3. Electrical Subsystem Model
The electrical system is the most important in the whole drive cycle.
The electrical system is subdivided by -
3.1. Induction Motor and Controller
3.2. Battery (Lithium-Ion Battery)
3.1. Induction Motor and Controller
This vehicle uses a three-phase induction motor as the main driving source The
Induction Motor is also called an asynchrony motor
It is an AC motor that works on the principle of electromagnetic induction most electric
cars use IP as their man die because as they offer high power torque density and speed
range and compact size.
• Induction Motor performance in field weakening constant power region but IM has low-
speed performance efficiency, heat loss which lead to low power factor and efficiency.
• Hence to control the speed and torque of the motor we need to use an IM controller.
The IM controller blocks implemented a torque based field-oriented controller with an
outer speed loop control.
The controller also implements the equation for speed control. torque determination
regular some basic formula that the blocks implements are
To calculate speed, frequency and poles formula required to calculate losses in the
motor
o The corresponding phases (AB) is connected to the motor controller the speed of
the motor is constantly regulated by its controller closed-loop speed control
(SpdFdk port)
o The vehicle speed in (m/s) is converted to motor speed in (rad) with the help of
unit conversion and signal specification block
o Taking a product of motor speed and acceleration a torque command is
generated. The lookup table takes input as (VehSpd) in rad which is then scaled
by accelerator command and the product of two is implemented as a torque
command
3.1.1 Torque Command Data
• The resultant motor torque signal is obtained from the bus selector.
• The resultant motor torque signal is obtained from the bus selector.
3.2. Battery (Lithium-Ion Battery)
• The Battery is the energy source of any system the battery used in the system is a
Datasheet battery which implements a model for the lithium-ion battery.
• The question arises that why most of the EVs uses lithium-ion cells as a source, like
any other battery because battery like a lead-acid battery which required constant
maintenance and monitoring, hydrogen cells which are quite bulky and expensive also
capacitor banks are used as a battery pack but they have a high discharge rate and
drain quickly.
• Hence the Lithium-Ion Battery eliminates all such disadvantages and requires less
maintenance and operational cost are less.
• Longevity-The average lithium-ion battery life span for a large capacity is more than
years. Safety-reduce the risk of accidents by eliminating exposures to flammable fuels
able to withstand even in the high temperature without explosions.
• Environment Impact-Lithium-Ion batteries provide significant environmental benefits
over fossil fuels. With the steady increase in electric vehicles, we can see an immediate
impact on the reduction in carbon emission. Hence knowing all such advantages of
lithium-ion manufacturers prefer using lithium cells as their main source of energy.
. The battery pack is packed with 30 numbers cells in series and 2 numbers of cells in
parallel each Ah and the rated voltage is 12.
• The Battery rated capacity is 100 volt the battery provides 1200kwh considering its
charging/ discharging
• Charging of battery if the applied current is to ampers, then it would be 100Ah/10A-10
hrs approximately. Discharging Battery Ah X Battery Volt/ Applied load say, 100Ah X
12V/100 watts-12 hrs (With 40% loss at the max-12-40).
The BattCurr and the BattVolt are connected to the motor controller respectively, the
batt SOC can be determined by the bus selector SOC is scaled to 100 by using gain
black.
4. Driver Subsystem Model
• The Driver block is basically a controller for the vehicle, it controls the acceleration,
and braking of the vehicle. The block is implemented with a PID controller which is
basically the main controller in the whole drive cycle
• The PID controller works as closed-loop speed control, it takes the input as a
reference speed and connects the error generated by the vehicle speeds.
• PID controller is tuned for adequate acceleration and deacceleration commandant is
done by limiting its output to upper and lower saturation Separating the output of the
PID to accelerate and deacceleration command
• We Tune a situation block for each command for acc command we use an upper
saturation value and for the deaccelerate command, we use a lower saturation value
• Tuning is Proportional, derivative and integral values we should be able to track the
reference speed. The below table gives us an idea for the manual tuning of the
controller.
Results
Output Plots:
Vehicle Speed Plot
Martiq Plot:
PwrLoss Plot :
BattCurr Plot :
MtrSpd Plot:
BattSoc Plot:
BattVolt Plot:
i. The simulation was run for about 2500 sec and we have obtained the result
shown above. There are 6 individual graphs showing the result for the motor and
the battery in this result, we see that a max torque was obtained The graph of the
battery SOC shows a linear and a slow discharge rate, we also observe a peak
of charging spik as a cause by the regenerėtive braking of the vehicle.
ii. The Result for the Vehicle speed and reference speed is shown below we can
see that the vehicle speed tracks the reference speeds of Artemis Motorway
thanks to the PID controller, the manual tuning of the PID controller help to track
the reference speeds.
CONCLUSION:
• We Create a MATLAB model of an electric car that uses a lithium-ion battery with a
suitable motor. By using suitable blocks from Simscape or Powertrain block set and we
Implement the vehicle speed control using Pl controller and generate brake and
accelerator commands configurations Model parameters
• we have seen System level the model run as per our reference input given with less
error in it due to PID controller.