EV Charger SMPS Based.pdf

Project Report on SMPS Based EV Charger.

1. A
PROJECT REPORT
On
(ELECTRIC VEHICLE CHARGER)


UNDER THE SUPERVISION OF
Mr. Suneel Kumar
Assistant Professor (EED)



Submitted By:
Lalit Kapoor (1873520033)
Nikhil Kumar (1873520037)
Krishna Pratap (1873520030)
Maneesha (1873520034)


Bachelor of Technology
In
ELECTRICAL ENGINEERING



RAJKIYA ENGINEERING COLLEGE, BIJNOR
SESSION: 2021-22

1

2. CONTENT



1. Certificate [ 4 ]
2. Declaration [ 5 ]
3. Acknowledgement [ 6 ]
4. Abstract [ 7 ]
5. Introduction [ 8 ]
6. Why this type of charger?
7. Hardware Components
8. Theory of operation of EV
9. Some glimpse of designing
10. Charging profiles
11. Advantages of EV charger
12. Conclusion
13. References
[ 9 ]
[ 10-17 ]
[ 18 ]
[ 19 ]
[ 20-22 ]
[ 23 ]
[ 24 ]
[ 25 ]






























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3. 3 
TABLE OF FIGURES
1. Fig. (a) - Functional Groups of Battery Charger
2. Fig. (b) - PFC Choke
3. Fig. (c) - Main LLC Transformer
4. Fig. (d) - Resonant Choke
5. Fig. (e) - Block Diagram of EV Charger
6. Fig. (f) - Circuit Diagram of SMPS
7. Fig. (g) - Simulink Model of EV Charger
8. Fig. (h) - Operation of EV
9. Fig. (i) - Battery
10. Fig. (j) - Chassis
11. Fig. (k) - Differential with motor
12. Fig. (l) - Final EV Design
13. Fig. (m) - Charging profile of Lithium Ion Battery
14. Fig. (n) - Charging profile of Lead Acid Battery

4. 4 





CERTIFICATE

This is to certify that the project report entitled Electric Vehicle Charger submitted by
LALIT KAPOOR, NIKHIL KUMAR, KRISHNA PRATAP, MANEESHA to Rajkiya
Engineering College, Bijnor, in partial fulfillment for the award of the degree of B.
Tech in (ELECTRICAL ENGINEERING) is a bona fide record of project work carried out
by them under my supervision. The contents of this report, in full or in parts, have not been
submitted to any other Institution or University for the award of any degree or diploma.
















(SIGNATURE)

Mr. Suneel Kumar
(Assist. professor of E.E.)

5. 5 

DECLARATION

We do hereby declare that this submission is our own work and that, to the best of my knowledge and
belief, it contains no material previously published or written by another person nor material which
to a substantial extent has been accepted for the award of any other degree or diploma of the university
or other institute of higher learning, except where due acknowledgment has been made in the text.





Name Roll No. Signature
Krishna Pratap 1873520030  
Lalit Kapoor 1873520033  
Nikhil Kumar 1873520037  
Maneesha 1873520034  




Date:

6. 6 



ACKNOWLEDGEMENT

We would like to express our deep and sincere gratitude to Mr. Suneel Kumar (Assistant Professor
of Electrical Engineering) of Rajkiya Engineering College, Bijnor, who gave us his full support and
encouraged us to work in an innovative and challenging project for educational field. His wide knowledge
and logical thinking gave me right direction all the time.
We are deeply grateful our project mentor/coordinator for his/her help and support provided at every step
of the project.
Last but not the least, we thank to all the teachers of Rajkiya Engineering College, Bijnor for their
support and co-operation.








Thank You

Lalit Kapoor (1873520033)
Nikhil Kumar (1873520037)
Krishna Pratap (1873520030)
Maneesha (1873520034)

7. ABSTRACT

This report analyzes the plug-in electric vehicle battery charging system using a non-isolated DC-DC
SEPIC converter which operates as a switched mode power supply (SMPS). The control of dc voltage
output is by varying the gating pulses duty cycle of the switch in the dc-dc converter using PID
controller based PWM technique. The 60 V, 30 A DC-DC SEPIC converter is designed to provide
non-inverting voltage buck from the rectified AC mains for charging deep cycle battery bank in an
electric auto rickshaw. The charger system is implemented using required hardware.














































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8. INTRODUCTION

Switched mode power supplies (SMPS) are extensively used in charging batteries. Designing high
performance battery chargers using DC-DC non-isolated power converters with low cost, small size,
and high efficiency makes it a challenge due to the electro-magnetic interference (EMI). The design
becomes more difficult for applications that demand high voltage gains with low input and output
current ripple. The single-ended primary inductor converter (SEPIC) is a DC-DC voltage converter
that is able to boost or buck a dc input voltage. One of the merits of a SEPIC converter is its non
invertion of the output voltage unlike the buck-boost converter; it also offers easy implementation of
magnetic coupling. But they usually suffer from higher switch voltage stresses and their control can be
complex, due to the two pairs of undamped complex poles in its duty cycle to output voltage gain.
Lithium-ion battery use in plug-in electric vehicle battery technologies has been high due to its high
power density and good depth of discharge but its high cost has made it a reason why Electric Vehicles
(EVs) are expensive and not affordable. The Lead acid battery is cheap, affordable and easily available
for use especially in developing countries where cost is a major factor in making purchase decisions.
A wide voltage range of the on board charger is mapped to a wide voltage range of Lead acid cell.































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9. Why do we choose this type of Charger?

This application note provides a detailed description of the main features and operation under both
steadystate and abnormal operating conditions of a 2 kW highly efficient natural convection-cooled
industrial battery charger for 48 V lead-acid and Li-ion batteries.

• In case larger batteries need to be charged or faster charge capability is needed, the battery
charger canbe connected in parallel with another unit to achieve this.

• High Power Factor (PF) and low Total Harmonic Distortion (THD) response at high line.

• Efficiency higher than 92 percent from 20 percent of the rated load (2 kW) upward when Vin
= 230 V AC, and efficiency higher than 91 percent of the rated load (1 kW) upward when Vin = 90 V
AC, during CCM.

• In case higher battery voltages are required, section 6 provides a list of changes that would be
necessaryto make at hardware level. Two different battery voltage ratings are considered: a) 72 V
(range 67.2 V to
86.4 V at 30 A max.) and b) 144 V (range 134.4 V to 172.8 V at 15 A max.).



































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10. HARDWARE COMPONENTS
1. Batteries: The batteries provide power for the controller. Three types of batteries: lead-acid, lithium
ion, andnickel-metal hydride batteries. Batteries range in voltage (power). An electric-vehicle battery
(EVB, also known as a traction battery) is a battery used to power the electric motors of a battery
electric vehicle (BEV) or hybrid electric vehicle (HEV). These batteries are usually rechargeable
(secondary) batteries and are typically lithium-ion batteries. These batteries are specifically designed
for a high ampere-hour (or kilowatt- hour) capacity.
Electric-vehicle batteries differ from starting, lighting, and ignition (SLI) batteries as they are designed
to givepower over sustained periods of time and are deep-cycle batteries. Batteries for electric vehicles
are characterized by their relatively high power-to-weight ratio, specific energy and energy density;
smaller, lighter batteries are desirable because they reduce the weight of the vehicle and therefore
improve its performance. Compared to liquid fuels, most current battery technologies have much lower
specific energy, and this often impacts the maximum all-electric range of the vehicles.



Fig. (a) - Functional Groups of Battery Charger
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11. 2.Charger Main Components :-
2.1 Functional groups (Fig. (a)): CoolMOS™ P7 superjunction MOSFET The two high-current
CM chokes L3 and L4 arebased on high-permeability toroid ferrite cores. Each of these has 2
× 1.8 mH inductance. The relatively high number of turns causes a considerable amount of
stray inductance, which ensures sufficient DM attenuation. In case the fuse is blown due to any
abnormal conditions during the operation of the converter, the C3 X capacitor is fully
discharged through resistors R1, R2 and R4 in order to prevent any electric shock injuriesto the
operator of the demo board. The line filter includes circuitry that limits the start-up inrush
current on the first half-cycle to 25 A. During normal operation the inrush current limit
impedance is bypassed by a relaycontact K1. The relay K1 is controlled by the PFC controller.



2.2 Dual-boost semi-bridgeless: PFC converter Although active PFC can be achieved by several
topologies, the dual-boost semi-bridgeless converter is a very attractive solution for high-power
supply solutions for the following reasons:
Compared to the standard/classic PFC rectifier based on a diode bridge (with two active
rectification diodes atall times), a single PFC MOSFET and a PFC diode, the dual-boost has
lower conduction losses because thereare always two power semiconductors in the current path
per AC semi-cycle (e.g. Q1 or Q3 + complementarylow-side diode from D3). However, for
ease of control and taking into account impedance on the returning path, even three can be active
(e.g. Q1 + complementary low-side diode from D3 Q2 or Q2 + complementarylow-side
diode from D3 Q1). •Higher efficiency at a higher power density compared to the same rated
powerstandard/classic PFC rectifier, due to less cooling effort and better heat spot distribution.
More efficient and easier to control compared to an interleaved PFC rectifier, as this is a
bridgeless topology with
need for phase shedding between
the PFC legs.














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12. 2.3 PFC boost inductor: The PFC choke (Fig. (b)) design is based on a toroidal high-performance
magnetic powder core. Toroidal chokes have a large surface area and allow a good balance,
minimizing core and winding losses, and achieving a homogeneous heat distribution without
hot spots. Hence they are suitable for systems that are targeting the highest power density
without forced air cooling. The part number is HS467075, which indicates an outer diameter
of the core of 47.6 mm, with a corresponding height of 18.92 mm, and a 75 µ permeability. The
winding was implemented using enameled copper wire AWG 14 (1.8 mm diameter). The
winding covers approximately 1.5 layers. This arrangement allows a good copper fill factor,
while still having good AC characteristics, and is a preferred fill form factor for high-power
toroidal inductors. There are 46 turns, taking advantage of the high permitted DC bias. The
resulting small-signal bias inductance is 358 µH.


Fig. (b) - PFC choke

2.4 LLC resonant half-bridge converter: The LLC resonant converter design is realized by two
clamping diodesacross the two split resonant capacitors. This configuration offers a couple
of important benefits:
1- Greatly reduced input current ripple, switch current and resonant capacitor voltage stress. This
will protect theconverter from destructive damage. Another benefit of this method is that it
doesn’t need an active control, and very simple to implement. Its response speed is fast, which
can provide cycle by-cycle current protection.
2- The voltage stress on the resonant capacitor is limited so that a low-voltage capacitor can be
used; another benefit is that by limiting the voltage on the resonant capacitor, it automatically
limits how much current can go through the resonant tank during each half switching cycle,
which in turn will limit the output current. Therefore cost reduction and extended lifetime are
achieved.







12

13. 2.5 The main transformer: The final structure of the main transformer is shown in Fig. (c); the
selected core used is E65/32/27 and the core material is the ferrite TDK PC47. This has been
developed so that the primary is realized in a “sandwich” technique using 16 turns of four layers
of litz wire, 45 strands and 0.1 mm diameter.This minimizes the AC losses due to skin and
proximity effect. The secondary is done with a copper band 20
× 0.5 mm. The transformer is built with the following specifications:
•Turns ratio (n): 13:3:3
• Primary terminal voltage: 400 V AC
• Primary windings: min. 630 × 0.071 mm, 2 × parallel
• Secondary terminal voltage: 46 V AC
• Secondary windings: min. 2000 × 0.071 mm, 2 × bifilar
• Frequency at no load: 140 kHz
• Frequency at full load: 90 kHz



Fig. (c) - Main LLC transformer

2.6 Resonant choke: In the case of the current design as shown in the Fig. (d), it has been decided
to use an external resonant inductor Ls.This is because the demo board is intended to be modified
for higher output battery voltages, so having the resonant inductance externally enables changing
the resonant tank in a more flexible way. The overall value of Ls including the contribution of the
transformer primary leakage inductance shall be: [Ls = 7.5 µH +
1.5 µH (XFMR leakage) = 9 µH] The external resonant choke is realized using a PQ40/40 core
with TDK PC47 ferrite core material and air gap approx. 6 mm.




13

14. Fig. (d) – Resonant Choke


















































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15. 2.7 Bias power supply: The PFC and LLC controllers and gate drivers as well as the control board need
an auxiliary power supply for start-up and operation. An auxiliary power supply of 6 W is designed
on-board using the ICE5QR4780AZ QR DCM Flyback controller with primary-side control. This
controller offers a lowpart count and relatively low-cost solution, eliminating the need for optocoupler
and feedback circuitry. In addition, QR topology ensures high efficiency, and optimizes losses. The
converter is powered from the outputof the PFC stage and must be able to start up prior to the PFC
stage being operational. For this reason, the circuit is designed to operate over a wide input voltage
range, 125 V DC to 450 V DC.







Fig. (e) - Block Diagram of EV Charger







Fig. (f) - Circuit Diagram of SMPS







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16. Fig. (g) - Simulink Model of EV Charger
3. Potentiometer: It is circular in shape and it is hooked to the accelerator pedal. The potentiometer,
also calledthe variable resistor, provides the signal that tells the controller how much power is it
supposed to deliver. Potentiometers are commonly used to control electrical devices such as volume
controls on audio equipment. Potentiometers operated by a mechanism can be used as position
transducers, for example, in a joystick. Potentiometers are rarely used to directly control significant
power (more than a watt), since the power dissipated in the potentiometer would be comparable to the
power in the controlled load.

4. DC Controller: The controller takes power from the batteries and delivers it to the motor. The
controller candeliver zero power (when the car is stopped), full power (when the driver floors the
accelerator pedal), or anypower level in between. If the battery pack contains twelve 12-volt batteries,
wired in series to create 144 volts, the controller takes in 144 volts direct current, and delivers it to the
motor in a controlled way .
The controller reads the setting of the accelerator pedal from the two potentiometers and regulates the
power accordingly. If the accelerator pedal is 25 percent of the way down, the controller pulses the
power so it is on 25 percent of the time and off 75 percent of the time. If the signals of both
potentiometers are not equal, the controller will not operate .


5. Motor: The motor receives power from the controller and turns a transmission. The transmission
then turns the wheels, causing the vehicle to run. An electric motor is an electrical machine that
converts electrical energy into mechanical energy. Most electric motors operate through the
interaction between themotor's magnetic field and electric current in a wire winding to generate force
16

17. in the form of torque applied on the motor's shaft. Electric motors can be powered by direct current
(DC) sources, such as from batteries, or rectifiers, or by alternating current (AC) sources, such as a
power grid, inverters or electrical generators. An electric generator is mechanically identical to an
electric motor, but operates with a reversed flow of power,converting mechanical energy into electrical
energy.




















































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18. THEORY OF OPERATION OF EV

When the driver steps on the pedal the potentiometer activates and provides the signal that tells the
controllerhow much power it is supposed to deliver. There are two potentiometers for safety. The
controller reads the setting of the accelerator pedal from the potentiometers, regulates the power
accordingly, takes the power fromthe batteries and delivers it to the motor. The motor receives the
power (voltage) from the controller and usesthis power to rotate the transmission. The transmission
then turns the wheels and causes the car to move forward or backward.
If the driver floors the accelerator pedal, the controller delivers the full battery voltage to the motor. If
the driver takes his/her foot off the accelerator, the controller delivers zero volts to the motor. For any
setting in between, the controller chops the battery voltage, thousands of times per second to create an
average voltage somewhere between 0 and full battery pack voltage.
See Figure 1.



Fig. (h) - Operation of EV

















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19. SOME GLIMPSE OF DESIGNING







Fig. (j) - Chasis














Fig. (k) - Differential with motor Fig. (l) - Final EV Design
















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Fig. (i) - Battery

20. CHARGING PROFILES

Charging profile for Li-ion battery: In case of a deep-discharged battery, the charging profile starts
with a pre-charging state (S0). In this state a low charging current is used to rebuild the cell voltage up
to the normal range. If the cell voltage reaches the normal operating area in the given time, the main
charging (S1) starts with a current ramp (Dt1 = 120 s). The preset current value in the main charging
state is 0.5 × Cnom. This value is valid for all Li-ion cells. For Li-ion batteries with a boost charge
capability (I1 greater than or equal to 1.0 × Cnom) you can choose a higher Cnom value and/or use the
parallel charging option. The S1 state is divided into two sections. The main section is charging with
the maximum current (0.5 × Cnom) or the maximum power (Pmax = 2000 W) up to a cell voltage of
3.9 V (equates to a capacity of ~ 90 percent). For the remainder of this state the charging current is
reduced to 0.1 × Cnom. If the charging voltage reaches a value of 4.1 V/cell, the battery charger
switches to the saturation stage (S2). Now the charging voltage remains constant until the charging
current goes below the cut-off limit (0.05 × Cnom). In this case the charging profile is complete and
the charging process is finished. The implemented charging profile for Li-ion batteries favors a gentle
charging to achieve a maximum count.


Fig. (m) – Charging profile of Lithium Ion Battery


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21. Charging profile of lead-acid battery: The implemented charging profile for lead-acid batteries is
also valid for various types of this battery. So it is possible to charge: WET, GEL, AGM, EFB and
VRLA batteries each with a nominal number of cells in series = 24. In case of a deep-discharged


battery, the charging profile starts with a pre-charging state (S0). In this state a low charging current is
used to rebuild the cell voltage up to the normal range. If the cell voltage reaches the normal operating
area in the given time, the main charging (S1 + S2) starts with a slow current ramp (Dt1 = 120 s). The
preset current value in the main charging state is (0.2 × Cnom). This value is valid for all lead-acid
types. The main charging state is divided into two sections (S1 and S2). The S1 section is the constant
current charging with the maximum current (0.2 × Cnom) or the maximum power (Pmax = 2000 W).
Up to a cell voltage of 2.35 V/cell the charging current (or power) is to remain constant.


The battery charger then switches to the absorption stage (S2). Now the charging voltage remains
constant until the current goes below the switch-over limit (0.02 × Cnom). If the main charging time
t1 (in S1) is greater than 30 min the charger switches to the after-charging state (S3); otherwise, the
charging process is finished and the charger begins trickle-charging without after-charging. After-
charging state (S3) the current remains constant (0.02 × Cnom) and the battery voltage can rise up to
2.45 V/cell. The S3 state is either finished by a time limitation [t3 = 1.0 × (t1 + t2); with t3min = 30
min and t3max = 240 min] or by a DU/Dt condition [DU/Dt less than 0.2 V/15 min]. When the charging
process has finished (S0 to S3), the charger enters a trickle-charging state (also called “ alancing”).
This state replaces the otherwise often-used float charging. Now the battery voltage is monitored and
in case it falls below 2.25 V/cell a constant current charging starts (0.02 × Cnom) until the battery
voltage reaches 2.35 V/cell again. This can be done an unlimited number of times. The implemented
charging profile for lead-acid batteries favors universal charging to suit a maximum number of battery
types. It is not optimized for fast charging or maximum capacity.













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22. Fig. (n) – Charging profile of Lead-Acid Battery


































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23. ADVANTAGES OF EV CHARGER


 Clean air commitment.
 Lower cost of driving for your community.
 EVs pave the way to other forms of clean transportation.
 Electric vehicles support environmental justice.
 EV charging increases property value.
 EVs help your community achieve climate change goals.
 Electric vehicles and smart charging help create a resilient local grid.










































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24. Conclusion

A module-based reconfigurable battery system (RBS) for high-voltage charging and low-voltage
driving is presented. It demonstrates a possible charging solution without additional power converters
for a safe-to-touch 48 V electric vehicle (EV) that uses existing high-voltage charging infrastructure.
For a scaled-up version of the designed demonstrator, the overhead cost of the reconfiguration system
is about 3% for a full-size EV. The performance loss in a World harmonized Light-duty vehicles Test
Procedure (WLTP) drive cycle is 0.24% due to the additional resistive losses. The cost savings
achieved through the reduced isolation effort required for low-voltage EVs may compensate for the
increased cost of the reconfiguration system. The interconnects between battery and drive are always
kept below 60 V. During charging, however, some interconnects inside the battery pack are applied to
high potential and need to be disconnected in case of a malfunction. During driving operation, the
highest voltage in the vehicle and battery remains below 60 V, making the EV safe-to-touch in accident
situations. Without special effort in battery selection and connection wire matching, the module
balancing was within ±10% and could be improved further. The module imbalances observed were not
found to systematically associate with switch and wire resistances, and thus should therefore relate to
the production spread of the used cells and modules.





























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25. References

1. Bubert, A.; Oberdieck, K.; Xu, H.; De Doncker, R.W. Experimental Validation of Design Concepts for
Future EV-Traction Inverters. In Proceedings of the 2018 IEEE Transportation Electrification
Conference and Expo (ITEC), Long Beach, CA, USA, 13–15 June 2018; pp. 795–802.
2. Turska, M. High Voltage Components in Commercial Vehicles; Lapin Ammattikorkeakoulu: Rovaniemi,
Finland, 2017.
3. Skoog, S. Component and System Design of a Mild Hybrid 48 V Powertrain for a Light Vehicle.
Ph.D. Thesis, Chalmers University of Technology, Gothenburg, Sweden, 2020.

4. Hayslett, S.; Van Maanen, K.; Wenzel, W.; Husain, T. The 48-V Mild Hybrid: Benefits, Motivation, and
the Future Outlook. IEEEElectrif. Mag. 2020, 8, 11–17.






































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