Design of a SI Cuk Converter based on Bridgeless Power Factor

Correction with Regenerative Braking

Swaliyabegum Mulla

1 a

and M. S. Aspalli

1 b

Department of Electrical and Electronics Engineering (Affiliated to VTU Belgaum)

Poojya Doddappa Appa College of Engineering, Kalaburagi (Affiliated to VTU Belgaum), Karnataka, India

Keywords: Cuk Converter, Power Factor Correction, High Gain Converter, Regenerative Braking.

Abstract: The size of a switched inductor (SI) based Cuk converter is lowered with increased power factor when the

bridge is removed from an electric car charging system. The traditional techniques for battery charging

involve two-stage power conversion. The single stage switching inductor topology improves the voltage

conversion ratio. A high gain bidirectional converter is introduced to power the motor for the operation of an

electric vehicle after the performance of the converter under steady state and transient situations is noted.

Software called MATLAB/Simulink is used to carry out the simulation job. In order to verify that the

suggested system operates as intended, a hardware model is created.

1 INTRODUCTION

Given the constantly increasing share of demand for

LEVs, the charging station outfitted utilizing a

superior method for improving power quality is

highly anticipated from the perspectives of both

power distributors and users. The current generation

of LEV chargers frequently begin with a dc-dc

converter that is either isolated or not, together with a

configuration of an unregulated rectifier and a dc bus

capacitor. When DBR and a big dc-link capacitor are

used together, the input's power factor (PF) and

overall system efficiency all suffer because they draw

harmonics-rich distorted current from the supply.

Power factor correction (PFC) largely eliminates

these flaws in conventional low power rating

converters. In an APFC approach, a dc-dc converter

is employed between DBR and CDC to improve the

source side of the converter's performance from the

standpoint of power quality(Lachvajderova et

al,2021)(Wang et al,2021). It is crucial to understand

that an APFC conversion, whether it is a single-stage

converter or a two-stage converter with

differentconfigurations, can perform a variety of tasks

in a charger. In a two -stage setup, an APF cuk

________________________

https://orcid.org/0009-0001-4998-6785

https://orcid.org/0000-0002-5483-6415

converter is utilized to satisfy source requirements,

while a second dc-dc converter is required to satisfy

load requirements. In single-stage converters,

however, a single APF cuk converter fulfils both

criteria. A number of two-stage converter designs

based on various APFC techniques have been

researched for the purpose of charging EVs and

LEVs. Each technique has benefits and drawbacks in

terms of component tally, conductance and switch

losses, control complexity, and effectiveness. To

improve efficiency by reducing conduction losses on

the APF cuk conversion stage, several bridgeless

APFC converters with partial or complete deletion of

the DBR have been recorded in the literature. The

presentation includes a full investigation of bridgeless

APF cuk converters (Bahrami et al,2020). Certain

bridgeless integrated charging techniques have

recently been presented as a way to keep the

advantages of two-stage converters while reducing

the number of parts and inefficiencies in the chargers

(Dulau at al.,2020). Integration of the power

electronic equipment reduces the overall number of

devices and associated losses. However, the rising

control complexity and high device pressures account

for their diminished appeal for LEV applications. The

ripple-free charging current is one of the two-stage

converter's primary advantages. The performance of

the battery, as has been asserted by a number of

authors, is unaffected by low-frequency fluctuations

in the pushing current when they are properly

Mulla, S. and Aspalli, M.

Design of a SI Cuk Converter Based on Bridgeless Power Factor Correction with Regenerative Braking.

DOI: 10.5220/0012524900003808

Paper published under CC license (CC BY-NC-ND 4.0)

In Proceedings of the 1st International Conference on Intelligent and Sustainable Power and Energy Systems (ISPES 2023), pages 107-115

ISBN: 978-989-758-689-7

107

regulated (Rachid et al., 2022). To address these

issues with two-stage converters, numerous

researchers have proposed alternate single-stage

converter topologies for EVs/LEVs together with

enhanced power quality at the source side. The single-

stage converters provide a low component count, high

power density, and an easy-to-understand control

design (Habib,2018). A properly designed single-

stage converter configuration may also provide

superior efficiency compared to its two-stage

converter. The common buck converter's high supply

current distortion at the zero crossing and the standard

boost converter's constrained output voltage

capabilities exclude their possible usage as an APFC

in single-stage LEV converters. The disadvantages of

buck and boost derived converters are therefore

typically eliminated when utilizing buck-boost

derived converters. The Cuk model of buck-boost dc-

dc converters has the least amount of output and input

current ripple. Traditional buck-boost dc-dc

converters, on the other hand, are less suitable to

provide a transformerless single-stage conversion for

the LEVs due to their low gain capabilities. Due to

the low battery voltage, the transformerless charger

architecture in LEVs operates at an extremely low

duty ratio, which eventually affects the charger's

dynamic efficiency and performance. The common

buck converter's high supply current distortion at the

zero crossing and the standard boost converter's

constrained output voltage capabilities exclude their

possible usage as an APFC in single-stage LEV

converters. The disadvantages of buck and boost

derived converters are therefore typically eliminated

when utilizing buck-boost derived converters. The

Cuk model of buck-boost dc-dc converters has the

least amount of output and input current ripple.

Traditional buck-boost dc-dc converters, on the other

hand, are less suitable to provide a transformerless

single-stage conversion for the LEVs due to their low

gain capabilities. Due to the low battery voltage, the

transformerless charger architecture in LEVs

operates at an extremely low duty ratio, which

eventually affects the charger's dynamic efficiency

and performance. Therefore, the majority of single-

stage LEV converters based on conventional dc-dc

converters require a transformer in order to achieve

the required dc voltage gain. However, the

transformer drives up the cost and size of the charger.

The leakage inductance of the transformer also

increases the voltage stress between the parts. The

transformerless charger architecture for LEVs based

on improved power quality is still seldom ever

discussed in academia. coupling inductors, converter

cascading, the use of multipliers, interleaved front

end structures, switched inductors, and hybrid

switched inductor-capacitor structures are recent

developments (Khalid et,2021) (Das et al,2021).

However, in the case of linked inductors, the coupling

coefficient has a significant impact on the operational

parameters of the converter. The quadratic converter

is more effective than a cascaded converter at

adjusting for increasing voltage and current stresses.

As a remedy to these issues, a switching dual network

composed of two to three diodes, split type inductors,

or capacitors is proposed. This charger is costly, has

a challenging control system, and has larger magnetic

components due to the CCM operation. This research

presents a single-stage Cuk converter-based modified

power factor improved converter. Because the dcm

mode of operation eliminates the need for sensors, the

controller design is straightforward. The converter's

bridgeless design results in a significant reduction in

the number of components used. The proposed

converter is put to the test using constant voltage and

constant current control techniques with variable

input voltage conditions. Once the vehicle is running

on battery power, the motor is powered via a high

gain bidirectional converter. Regenerative braking

can be used and extend the vehicle's running time

because of the bidirectional property.

2 SYSTEM DESCRIPTION

The proposed system is provided below in Fig 1.

Fig 1: Proposed system Block diagram.

The ac supply is connected to the BSIC converter

in this case while the car is charging so that the battery

can be charged while switch 1 (S1) is ON and switch

2 (S2) is OFF. The battery serves as the load in this.

The control loop regulates the voltage and current of

the battery. S1 is OFF (the ac source is disconnected)

and S2 is ON (the motor is connected) when the car

starts. The battery serves as the supply in this. The

measured speed of the DC motor is fed into the speed

ISPES 2023 - International Conference on Intelligent and Sustainable Power and Energy Systems

108

control loop, which regulates the output voltage of the

bidirectional converter, causing the measured speed

to match the reference speed.

2.1 BSIC Converter and Control

The bridgeless Cuk converter circuit is provided

below:

Fig 2: circuit diagram for Single phase Single.

Stage Bridgeless switched Inductor Cuk

Converter (BSIC) Power Factor Correction(PFC)

Converter.

This configuration offers a single-stage ac-dc

converter with high voltage conversion capability and

superior power quality on the supply side for the LEV

charging application. The rated voltage (Vs)

specification for the single-phase supply that powers

the bridgeless construction on the front end is 220 V,

50 Hz. The source inductor (Li) serves as the input

inductor for the Cuk converter as well as a gradient

with the source current (Is). The leading leg of the

rectifier bridge is made up of diodes, D1 and D2,

while the second leg is made up of two active

switches, S1 and S2. This differs from the standard

DBR, which consists of a combination of four diodes.

In order to reduce control complexity, While the

switches (S1 and S2) run simultaneously regardless

of the supply voltage polarity, D1 and D2 operate

during each of the supply voltage's two half-cycles,

respectively.

On the load side, a SI network is provided that

combines two inductors (Lo1 and Lo2) with two

diodes (D3 and D4). The total gain of the charger is

improved by charging the output inductors in series

and discharging them in parallel. A battery with a 48

V and 1.3 Ah voltage rating serves as the load. The

converter control is also made simpler and less

expensive by employing the fewest number of

sensing devices possible to implement the charger's

control.

Fig 3: mode 1 operation of BSIC.

The following list includes the aforesaid converter's

operational modes:

Mode 1:

In this, the source side inductance and both power

electronic switches S1 and S2 are in operation. With

the help of the input voltage source, Li is being

charged, while C1 is being discharged to supply

power to the inductors Lo and battery.

Mode 2:

In this case, the input side inductor begins to

discharge while both power electronic switches are in

the OFF state. Along with conducting is the body

diode of S2, the diodes D1, D3, and D4. While the

inductors Lo are discharging, the capacitor C1 begins

to charge.

Fig 4: Operation of Mode 2 of BSIC.

Mode 3:

The diodes D3 and D4 stop conducting because of the

reverse bias. While C1 is still charging, the input side

inductance Li is still discharging. The inductors' Low

state allows the current to freely flow through them

without being charged or discharged.

Design of a SI Cuk Converter Based on Bridgeless Power Factor Correction with Regenerative Braking

109

Fig 5: Operation of Mode 3 of BSIC.

The voltage conversion ratio of the cuk converter is

provided below:

where D1 represents the diodes (D5 and D6) duty

ratio and M= Vbat/Vin.

The load side inductance value is calculated as

provided below:

The source side inductance value is calculated for

CCM is provided below:

The value of C1 is calculated as

where ωres is resonant frequency

CDC is calculated as

where f

line

is the supply frequency.

2.2 High Gain Boost Converter

Similar to a resistor, an inductor behaves as an

appliance and uses energy when it is charged, and

when it is discharged, it acts as a source of energy.

Because the voltage it creates during the phase of

discharge is based on the rate of current change rather

than the starting charging voltage, a variety of

voltages at the input and output are possible. The

following graphic shows the basic layout for a boost

converter with a high voltage conversion ratio:

Fig 6: Basic configuration of high gain boost converter.

The proposed converter operates in one of two

modes while the power electronic switch S is in

operation and in both modes when switch S is turned

off. Inductors L1 and L2 get charged simultaneously

by the source voltage Vin through Diodes D1 and D2,

respectively, when switch S is switched ON. A single

capacitor, four diodes, and a MOSFET switch with a

PWM switching rate make up the power circuit

approach. Capacitor C is discharged by the load. D3

and D4 reverse biased diodes were available. The

operation is depicted in the accompanying figure

while switch S is turned ON.

Fig 7: Operation of converter when switch is ON.

Both inductors are draining while the power

electronic switch S is turned off, and the voltage

source is connected in series by diodes D3 and D4.

D1 and D2 are not conducting at this time.

Fig 8: Operation of converter when switch is OFF.

The design equations for the high gain dc-dc

converter is provided below:

The duty ratio of the high gain converter is

provided below.

𝑉

𝑜

𝑉

𝑖𝑛

1 + 𝐷

1 − 𝐷

ISPES 2023 - International Conference on Intelligent and Sustainable Power and Energy Systems

110

The inductor ripple current is provided below

The inductor value is provided by the relation shown

below

The load capacitor value is calculated as follows:

Where ΔVOUT = desired output voltage ripple.

Switches Q2 and Q3 are used in place of the

diodes D2 and D3 for bidirectional power flow; Q3

works at a PWM frequency while Q2 operates at a

lower frequency solely to provide a path for the load

(the battery serves as the load during regenerative

braking).

Fig 9: circuit diagram of converter when diodes are placed

with switches Q1&Q2.

2.3 Control Structure of Basic

Converter

The suggested converter is used to control the

battery's charging current in both CC and CV modes,

depending on the circumstance. While the outer loop

controls variations in Vbat, the inner loop controls

Ibat and maintains UPF operation with the least

amount of distortion. The reference battery current

(Ibat) is obtained by matching the Vbat and Vbat for

the outer loop, and the error (Vbate) is fed into the

proportional-integral (PI) control as an input. The

voltage PI controller's output serves as Ibat. The

specified outer loop expressions are:

where kpV stands for the proportional gain of the

voltage PI controller, kiV for the integral gain, and k

for the sampling moment. Inner loop control is

implemented by comparing the current used to charge

Ibat to Ibat, and sending the error (Ie) to the control

circuit after that.The needed duty ratio (mc) is

provided by the PI controller's output as

where kpI and kiI, respectively, are the gains of the

current PI controller. Next, the duty ratio (mc) is

compared to a carrier waveform. Switch (S1 and S2)

receive the relevant gate drive signals from the

comparison.

2.4 Speed Control Strategy

The DC reference voltage (𝑉

∗

𝑑𝑐

) is provided below is

calculated with the help of reference speed.

The reference voltage (𝑉

∗

𝑑𝑐

) is compared with the

actual load voltage (𝑉

𝑑𝑐

) and the error voltage (𝑉

𝐸

) is

provided below as

The generated error is given to proportional–integral

(PI) control, which provides the reference voltage 𝑉

𝐶

as follows:

The pulses generated for the boost converter is as

follows:

{If 𝑀

𝐶

< 𝑉

𝐶

gating pulse is HIGH}

{If 𝑀

𝐶

≥ 𝑉

𝐶

gating pulse is LOW}

3 SIMULATION SETUP &

RESULTS

The simulation parameters for the proposed

converter are shown below in Table I:

Input Voltage

(160 -230) V

Input power

1500W

Switching Frequency

2 KHZ

Inductor

9.1mH

Coupling Capacitor

55.6µF

Output Capacitor

2mF

Battery voltage

48V

Battery capacity

1.5Ah

Design of a SI Cuk Converter Based on Bridgeless Power Factor Correction with Regenerative Braking

111

DC Motor parameters

150V, 500W, 1500

rpm

The simulation circuit for the cuk converter with

PI controller is provided below in fig.10.

Figure 10: Simulation circuit.

In this, the supply voltage of 230V is applied to

the proposed converter from t=0 to t=0.3s. Then the

supply changed from 230V to 160V at t=0.3s. During

this two modes, the battery will be charging and the

motor will be in standstill condition. The simulation

circuit for the high gain bidirectional converter with

PI controller is provided below:

Figure 11: Bii-directional converter simulation.

The motor begins to function in the forward

direction and the battery begins to discharge at t=0.6s

(mode 3). Regenerative braking is performed to the

motor at t=0.95s (mode 4), and the charge stored in

the motor windings is extracted to recharge the

battery.

In mode1 and 2, the supply is connected and

charges the battery of the EV. The supply voltage and

current is provided is provided below:

Figure 12: Supply voltage and current.

The supply voltage in this is around 220V and 7A.

The supply charges the battery, and the waveforms of

its voltage and%SOC are shown below

voltage), and the SOC:

This keeps the battery voltage at 52V (which is

greater than the 48V battery nominal percentage is

rising. At t=0.6s, the supply is cut off, and as the

battery begins to discharge and deliver power to the

car, the%SOC starts to fall. Below are the motor

voltage and current values:

Figure 13: Motor voltage and current.

ISPES 2023 - International Conference on Intelligent and Sustainable Power and Energy Systems

112

At t=0.6s, the motor begins to run in the forward

direction with a positive current flow, and at t=0.95s,

regenerative braking is performed with a negative

current flow, or it is supplied back to the battery to

charge it. Below is a list of the battery voltage and

SOC during regenerative braking:

Figure 14: battery voltage and SOC.

The battery is first charged by the source until

t=0.6s, resulting in a high battery voltage and rising

SOC. The soc starts to decrease as the engine turns on

at time t=0.6s as a result of battery discharge.

Regenerative braking is used at time 0.95 seconds,

which recharges the battery once more and raises the

voltage and %SOC.The %THD of the supply current

is provided below:

Figure 15: Total Hamonic Distortion.

The %THD of the supply current is around 2.01%.

The efficiency of the proposed system is provided

below: With an efficiency of about 95%, the input

power is in the range of 1570W and the output power

is about 1500W.

Figure 16: Simulation results.

Using a battery of 12V, 2.2Ah and a BSIC

converter with an output voltage of 24V, 50 Hz, a

hardware prototype model of the proposed converter

is created. When the battery is being discharged, the

input voltage of the battery is 12V, and the load

voltage of the high gain converter is 48V. The

hardware specifications are listed in Table II below.

Table 2: Hardware Parameters.

The suggested converter uses an Arduino uno

control to generate the pulses, which are then sent to

the driver circuit (TLP 250) to drive the mosfets IRF

250. Below are the input voltage waveforms:

Figure 17: Voltage.

Design of a SI Cuk Converter Based on Bridgeless Power Factor Correction with Regenerative Braking

113

In this the voltage division is 10V/div and the input

voltage is around 24V. It is provided to charge the

battery. The battery voltage is provided below:

Figure 18: Battery charging and Discharging.

In battery discharging mode, the battery voltage is

provided as input and the load voltage is provided

below:

Figure 19: Load voltage.

The load voltage of the high gain converter is

around 40.4V.

Fig 20: Prototype model of proposed converter.

4 CONCLUSION

The size of the converter is decreased as the bridge is

removed from the switched inductor (SI) based Cuk

converter that was designed in this research for use

with electric vehicles. A high gain bidirectional

converter is introduced to power the motor for the

operation of an electric vehicle after the performance

of the converter under steady state and transient

situations is noted. Regenerative braking is used to

extend the vehicle's range by restoring energy from

the motor to the battery. The simulation results show

that the proposed converter is 95% efficient. A

hardware prototype model was created, and the

suggested system's functionality was checked.

REFERENCES

Lachvajderova, Laura & Kadarova, Jaroslava.

(2021)Analysis Of Internal Combustion Engine

Vehicle, Battery Electric Vehicle And Emissions From

Transport. 21. 21-33.

Wang, L., Qin, Z., Slangen, T., Bauer, P., & van Wijk, T.

(2021). Grid Impact of Electric Vehicle Fast Charging

Stations: Trends, Standards, Issues and Mitigation

Measures - An Overview. IEEE Open Journal of Power

Electronics, 2, 56–74. https://doi.org/10.1109/

ojpel.2021.3054601

Bahrami, Ali. (2020). EV Charging Definitions, Modes,

Levels, Communication Protocols and Applied

Standards. 10.13140/RG.2.2.15844.53123/11

Dulau, Lucian Ioan & Bica, Dorin. (2020). Effects of

Electric Vehicles on Power Networks. Procedia

Manufacturing. 46. 370-377.

10.1016/j.promfg.2020.03.054.

Khalid, Mohd & Khan, Irfan & Hameed, Salman & Asghar,

M. & Ro, Jong-Suk. (2021). A Comprehensive Review

on Structural Topologies, Power Levels, Energy

Storage Systems, and Standards for Electric Vehicle

Charging Stations and Their Impacts on Grid. IEEE

Access. PP. 1-1. 10.1109/ACCESS.2021.3112189.

Das, Manoj & Jain, Sachin. (2021). Review on

Optimization Techniques used for Scheduling of

Electric Vehicle Charging. 1-6.

10.1109/CAPS52117.2021.9730621.

Rachid, A., El Fadil, H., Gaouzi, K., Rachid, K., Lassioui,

A., El Idrissi, Z., & Koundi, M. (2022). Electric Vehicle

Charging Systems: Comprehensive

Review. Energies, 16(1), 255. https://doi.org/10.3390/

en16010255

Habib, S., Khan, M. M., Abbas, F., Sang, L., Shahid, M. U.,

& Tang, H. (2018). A Comprehensive Study of

Implemented International Standards, Technical

Challenges, Impacts and Prospects for Electric

Vehicles. IEEE Access, 6, 13866–13890.

https://doi.org/10.1109/access.2018.2812303

ISPES 2023 - International Conference on Intelligent and Sustainable Power and Energy Systems

114

Sanguesa, J. A., Torres-Sanz, V., Garrido, P., Martinez, F.

J., & Marquez-Barja, J. M. (2021). A Review on

Electric Vehicles: Technologies and Challenges. Smart

Cities, 4(1), 372–404. MDPI. https://doi.org/10.3390/

smartcities4010022

Sanguesa, J. A., Torres-Sanz, V., Garrido, P., Martinez, F.

J., & Marquez-Barja, J. M. (2021). A Review on

Electric Vehicles: Technologies and Challenges. Smart

Cities, 4(1), 372–404. MDPI. https://doi.org/10.3390/

smartcities4010022

Design of a SI Cuk Converter Based on Bridgeless Power Factor Correction with Regenerative Braking

115