Urban transportation has a solution in the form of electric vehicles (EVs) which can provide a solution to environmental as well as economic problems of the society which is the major discussion point now a day’s. Generally, for >400 W battery charging system two-stage cascaded ac-dc and isolated dc-dc converter for power conditioning is used. Moreover, to reduce conduction losses and variation in the DC link voltage many topologies but these are associated with drawbacks of a large number of passive element and reduced power density. In isolated dc-dc converter stage efficiency, reliability, power density, compliance, and isolation are some important features for selecting a suitable configuration.

1. Abstract
A choice of logical converter topology plays a notable role in the battery
charging of electric vehicles (EVs). In this paper, snubber less stage of
rectifier cascaded with snubber less stage of the dc-dc converter is proposed
in which stage I eliminates the need of front-end rectifier, and no further
circuitry is required for switching operation of rectifier stage. Due to pulse
width modulation (PWM) switches share the samegating signal for positive
as well as negative cycle operation. Second stage converter uses
asymmetrical pulse width modulation (APWM) technique in which zero
voltage switching (ZVS) is achieved for all active switches, and near zero
current switching (ZCS) for low side, active switches are attained duringthe
charging range of the battery. The size of auxiliary inductance required
is decreased for ZVS with APWM compared to previously proposed
APWM with snubber circuitry. Due to a reduction in the size of auxiliary
inductor andabsence of snubber circuit results in an efficient battery charger
topology. The MATLAB simulation is done of the proposed converter to
validate the results.

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CONTENTS
Title Page 1
Certificate 2
Declaration 3
Abstract 4
Acknowledgements 5
Contents 6
List of Figures 7
Chapter 1: INTRODUCTION 8-9
1.1 Introduction 8
1.2 Problem Statement 9
Chapter 2: PROPOSED MODEL 10
Chapter 3: CIRCUIT SWITCHING MODES 11-12
Chapter 4:CIRCUIT DESIGN AND OPERATION 13-20
4.1 Hardware
4.2 Software
13
13
4.3 Modes of operation
4.4 Simulink Representation
14-19
20
4.5 Subsystem 20
Chapter 5: RESULTS 21-25
5.1 Simulation Results 21-24
5.2 Global annual sales Graph 24
5.3 Benefits of EV battery charging 25
5.4 Advantages of EV battery charging 25
5.5 Disadvantages of EV battery charging 25
Chapter 6: CONCLUSION 26
Chapter 7: FUTURE SCOPE AND REFERENCES 27

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LIST OF FIGURES
Figure 1: Electric vehicle battery charging station 9
Figure 2: Block Diagram 10
Figure 3: Circuit structure 11
Figure 4: Circuit Diagram 13
Figure 5: Mode of operation -1 14
Figure 6: Mode of operation -2 15
Figure 7: Mode of operation -3 15
Figure 8: Mode of operation -4 16
Figure 9: Mode of operation -5 16
Figure 10: Mode of operation -6 17
Figure 11: Mode of operation -7 17
Figure 12: Mode of operation -8 18
Figure 13: Mode of operation -9 18
Figure 14: Mode of operation -10 19
Figure 15: Mode of operation -11 19
Figure 16: Simulink Representation Diagram 20
Figure 17: Subsystem diagram 20
Figure 18: Annual sales Graph 24

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CHAPTER 1
INTRODUCTION
1.1 INTRODUCTION
 Urban transportation has a solution in the form of electric vehicles
(EVs) which can provide a solution to environmental as well as
economic problems of the society which is the major discussion point
now a day’s.
 Generally, for >400 W battery charging system two-stage cascaded ac-
dc and isolated dc-dc converter for power conditioning is used.
 Moreover, to reduce conduction losses and variation in the DC link
voltage many topologies but these are associated with drawbacks of a
large number of passive element and reduced power density.
 In isolated dc-dc converter stage efficiency, reliability, power density,
compliance, and isolation are some important features for selecting a
suitable configuration.
 Usually, isolated dc-dc converters with phase shifted modulation
(PSM) has been preferred by many researchers, but it has various
drawbacks like duty cycle loss, secondary rectifier diode having high
voltage spikes, electromagnetic induction (EMI), zero voltage
switching (ZVS) is associating with narrow load range for active
switches.

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1.2 PROBLE STATEMENT
 If the charging process is done without any control or balancing, which
results improper charging.
 Using a single converter, the battery cannot meet the ratings.
 For this reason, controlling techniques are introduced.
Fig 1. Electric vehicle battery charging station

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CHAPTER 2
PROPOSED MODEL
 The general overview of the proposed topology in which two stages of
the converter is controlled by using PI controller separately.
 Stage I can maintain constant dc link voltage with low conduction and
switching losses which acts as an input for stage II of the converter. In
stage II isolated dc-dc converter is used so that higher power
applications should easily achieve.
 In this paper, an EV battery charger topology is proposed which is
ideally suitable for 3.8 KW battery charging. Stage I of the proposed
topology does not contain a diode bridge rectifier, and stage II
comprises of the isolated dc-dc converter which ensures ZVS turn on
for all active switches and ZCS turn off for output diode switches over
the entire range of battery charging. This converter ensures high
efficiency, simple control, and high reliability.
 In this topology, inductor size, the current flowing through it and
conduction loss at the primary side is compared with previously
proposed topology Hence, the overall efficiency of the proposed
topology gets increases concerning conventionally used PSM gating
method topologies. To control switching simple PI controller is used in
the closed-loop analysis.
Fig 2. Block diagram

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CHAPTER 3
CIRCUIT SWITCHING MODES
1) Zero Voltage Switching.
 Zero Voltage Switching (ZVS) means that the power to the load (heater
or cooler or other device) is switched on or off only when the output
voltage is zero volts.
 The ZVS controls the load in a manner similar to the thermostat and
dimmer stat but the relative on/off times are measured in cycles.
 The zero voltage switch is designed to always switch the thyristors
(TRIACs or SCRs) as close as possible to the time when the supply
voltage waveform crosses the zero line, or passes through zero. If a
thyristor is triggered at the zero crossing, the RFI generated will be
almost negligible and this particular disadvantage of phase control is
overcome.
 Control over average load power is achieved by switching the load on
in bursts. For example, a low level of load power may be achieved by
switching the thyristor on for five cycles and off for twenty cycles.
Fig 3. Circuit Structure

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2) Zero current Switching.
 ZCS can eliminate the switching losses at turnoff and reduce the
switching losses at turn-on. As a relatively large capacitor is connected
across the output diode during resonance, the converter operation
becomes insensitive to the diode's junction capacitance.
 When power MOSFETs are zero-current switched on, the energy stored
in the device's capacitance will be dissipated. This capacitive turn-on
loss is proportional to the switching frequency.
 During turn-on, considerable rate of change of voltage can be coupled
to the gate drive circuit through the Miller capacitor, thus increasing
switching loss and noise. Another limitation is that the switches are
under high current stress, resulting in higher conduction loss. However,
it should be noted that ZCS is particularly effective in reducing
switching loss for power devices (such as IGBT) with large tail current
in the turn-off process.

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CHAPTER 4
CIRCUIT DESIGN AND OPERATION
4.1 HARDWARE:
 AC-DC Converter
 DC-DC Converter
 Li ion Battery
 Capacitors
 Diodes
 Inductors
 Transformers
 Switches
4.2 SOFTWARE:
 MATLAB SOFTWARE (R2009a)
• Design and implementation of circuit diagram by using Simulink.
Fig 4. Circuit Diagram

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4.3 MODES OF OPERATION:
 The operating principle of the proposed topology is divided into the
mode I to mode IX for understanding the working of topology.
 It is sub divided into eleven consecutive time intervals where change
is observed in voltage and current characteristics during charging of Li-
ion battery.
 S1,S2 are in ON condition and capacitor C1 discharge through S1 and
S2 switches.
Fig 5. Mode-1

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 At the end of mode1 lower capacitor discharge takes place as same as
upper capacitor.
 S3 is in OFF state and S6 is in ON state.
Fig 7. Mode-3
Fig 6. Mode-2

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 In this mode the upper capacitor '2Ca' charges through switch S5.
 Both the upper and lower capacitors are discharged through S5 and S6
switches respectively.
Fig 8. Mode-4
Fig 9. Mode-5

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 S1 and S2 are in OFF state and C1 is in charging condition.
Fig 10. Mode-6
Fig 11. Mode-7

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 Conduction takes place through S6 and S4 is conducting.
Fig 12. Mode-8
Fig 13. Mode-9

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 Upper capacitor is charged through body Diode S3 and lower capacitor
gets discharged through S4.
Fig 14. Mode-10
Fig 15. Mode-11

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4.4 SIMULINK REPRESENTATION:
4.5 SUB SYSTEM:
Fig 16. Simulink Representation Diagram
Fig 17. Subsystem Diagram

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CHAPTER 5
RESULTS
5.1 SIMULATION RESULTS:
 Pulse signals which are applying to the switch (MOSFET).
 Voltage waveforms across the switch S3.
 Voltage waveforms across the switch S4.

18. An Efficient Topology For Electric Vehicle Battery Charging
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 Voltage waveforms across the switch S5.
 Voltage waveforms across the switch S6.
 Current waveforms across the capacitor C1 while charging and
discharging time.

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 Current waveforms across the capacitor C2 while charging and
discharging time.
 Charging and discharging current of resonant capacitor.
 Current waveforms are across the auxiliary inductor.

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 Waveforms across input current for the DC-DC converter.
5.2 GLOBAL ANNUAL SALES OF EV’S:
Fig 18. Annual sales graph

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5.3 BENEFITS OF EV BATTERY CHARGING:
 Charging process is managed and controlled.
 Provides a cost-effective solution.
 Indirectly provides a eco friendly alternative.
 Exploits maximum use of already available infrastructure thus enables
a quick market penetration of EV’s.
5.4 ADVANTAGES OF EV BATTERY CHARGING:
 One of the best advantages of using the EV is it saves the environment
to be polluted from the fossil fuels. With the increase in the population
and their desires which is causing global warming can be reduced with
the EV.
 More quiet.
 Cheaper and easy to charge.
 Best speed experience.
5.5 DISADVANTAGES OF EV BATTERY CHARGING:
 It consumes time depending on the charger source is used.
 The unavailability of the required charging stations in India.
 Apart from AC chargers, DC chargers are more powerful and faster,
they can charge an electric car with a maximum range of 40 miles in
just one hour. But, DC chargers are very expensive.
 Though EV has better facilities to its consumers it also has both
advantages and disadvantages.

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CHAPTER 6
CONCLUSION
 The performance of the EV battery charging strategy considering
operating modes are demonstrated through simulation of resonant
converters.
 These converters with various configurations are shown in MATLAB
software to obtain the exact result of the battery charging.
 A more sophisticated control strategy for different levels with new
configurations can be extended from the result of this work.
 Li-ion batteries can be recharged according many different charging
techniques which can more or less complicate the charger architecture
and control.
 In particular, the standard charging strategy are simplest since they
don’t require model information to charge the battery. Furthermore,
they can be realized with very basic circuits, keeping the costs of the
charger to a minimum.
 On the other hand, the charging strategies based on electrochemical
models, taking into account the internal dynamics of the battery,
consider also the aging of the battery and other constraints, hence
resulting in greater accuracy and. All this is at the expense of cost and
computational difficulty.
 Finally, the silicon switching devices are expected to be replaced by
wide bandgap silicon carbide (SiC) devices in order to allow a
remarkable reduction in charger’s weight and volume.

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CHAPTER 7
FUTURE SCOPE
 This project will enhance the efficient usage of wastage power while
charging the battery.
 To provide an eco-friendly environment.
 To implement the charging stations instead of Filling stations.
 Beneficiary in conservation of Renewable sources.
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