bridgeless buck boost converter-fed bldc motor drive with

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ISSN 2348–2370

Vol.08,Issue.03,

March-2016,

Pages:0505-0512

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Bridgeless Buck–Boost Converter-Fed BLDC Motor Drive with Fuzzy

Based Power Factor Correction B. V. P. CHAITANYA

1, AFROZ SHAIK

2

1PG Scholar, Dept of EEE, Guntur Engineering College, Yanamadala, Guntur (Dt), AP, India.

2Assistant Professor, Dept of EEE, Guntur Engineering College, Yanamadala, Guntur (Dt), AP, India.

Abstract: The devices typically utilized in industrial,

commercial and residential applications got to undergo

rectification for their correct functioning and operation.

Hence there's a requirement to cut back the line current

harmonics thus on improve the power factor of the system.

This has led to designing of Power factor Correction circuits.

This project presents a Power Factor Corrected (PFC)

bridgeless (BL) Buck–Boost converter fed Brushless Direct

Current (BLDC) motor drive as a cost-effective answer for

low-power applications. The conventional PFC scheme of

the BLDC Motor drive utilizes a Pulse Width Modulated -

Voltage Source Inverter (PWM-VSI) for speed control with

a constant dc link voltage. This offers higher switching

losses in VSI because the switching losses increase as a

square function of switching frequency. A BL configuration

of the Buck–Boost converter is proposed that offers the

elimination of the diode bridge rectifier, thus reducing the

conduction losses related to it. A PFC BL buck–boost

converter is designed to operate in discontinuous inductor

current mode (DICM) with Fuzzy logic controller to produce

an inherent PFC at ac mains. The simulation results are

given by using Matlab/Simulink software.

Keywords: Brushless Direct Current (BLDC) Motor,

Bridgeless (BL) Buck–Boost Converter, Discontinuous

Inductor Current Mode (DICM), Power Factor Corrected

(PFC), Power Quality.

I. INTRODUCTION

Brushless DC (BLDC) motors are recommended for many

low and medium power drives applications because of their

high efficiency, high flux density per unit volume, low

maintenance requirement, low EMI problems, high

ruggedness and a wide range of speed control.[1-2] Due to

these advantages, they find applications in numerous areas

such as household application, transportation (hybrid

vehicle), aerospace, heating, ventilation and air conditioning

(HVAC), motion control and robotics, renewable energy

application etc. The BLDC motor is a three phase

synchronous motor consisting of a stator having a three

phase concentrated windings and a rotor having permanent

magnets. It doesn‟t have mechanical brushes and

commutator assembly, hence wear and tear of the brushes

and sparking issues as in case of conventional DC machines

are eliminated in BLDC motor and thus has low EMI

problems.[3-5] This motor is also referred as electronically

commutated motor (ECM) since an electronic commutation

based on the Hall-Effect rotor position signals is used rather

than a mechanical commutation. A BLDC motor when fed

by a diode bridge rectifier(DBR) has higher conduction

losses. The high conduction loss caused by the high forward

voltage drop of the bridge diode begins to degrade the

overall system efficiency. The heat generated within the

bridge rectifier may destroy the individual diodes. Hence, it

becomes necessary to utilize abridge rectifier with higher

currenthandling capability or heat dissipating characteristics.

This increases the size and cost of the power supply,

which is unacceptable for an efficient design. Bridgeless

topology seems to be the best solution for reducing the

conduction and switching losses of the converter. Up to

now, more than 80% of the controllers are PI (Relative

and vital) controllers on the grounds that they are effortless

and straightforward . The velocity controllers are the routine

PI controllers and current controllers are the P controllers to

accomplish superior commute. Fuzzy Logic can be

considered as scientific hypothesis joining multi esteemed

rationale, likelihood hypothesis, counterfeit consciousness

to recreate the human approach in the arrangement of

different issues by utilizing an estimated thin king to

relate diverse information sets and to make choices. It

has been accounted for that fuzzy controllers are more

powerful to plant parameter changes than traditional PI

controllers and have better clamor dismissal capacities.

This paper presents a BL buck–boost converter fed BLDC

motor drive with variable dc link voltage of VSI for

improved Power Quality at ac mains with reduced

components and superior control.

II. PROPOSED SYSTEM

The proposed BL buck–boost converter based VSIfed

BLDC motor drive is shown in Fig.1. The parameters of

the BL Buck–Boost converter are made such that it operates

in Discontinuous Inductor Current Mode (DICM) to attain

an inherent Power Factor Correction at ac mains. The

speed control of BLDC motor is accomplished by the

dc link voltage control of VSI using a BL Buck–Boost

converter. This reduces the switching losses in VSI because

B. V. P. CHAITANYA, AFROZ SHAIK

International Journal of Advanced Technology and Innovative Research

Volume.08, IssueNo.03, March-2016, Pages: 0505-0512

of the low frequency operation of VSI for the electronic

commutation of the BLDC motor.

Single

phase AC

mains

LC

filterBL Buck - Boost

Converter

VSIBLDC MOTOR

HALL EFFECT

POSITION SENSING

CONTROL UNIT

SAW-TOOTH

GENERATOR

PWM

GENERATOR ELECTRONIC

COMMUTATION

REF VOLTAGE

GENERATORREF SPEEDVOLTAGE

CONTROLLER

+

Fig.1.Block diagram of PFC BL-BUCK BOOST

Converter fed BLDC motor drive.

In the proposed arrangement of bridgeless Buck -Boost

converter has the base number of parts and slightest

number of conduction gadgets amid every half cycle of

supply voltage which administers the decision of BL Buck-

Boost converter for this application. The operation of

the PFC bridgeless Buck-Boost converter is ordered into

two parts which incorporate the operation amid the positive

and negative half cycles of supply voltage and amid the

complete exchanging cycle as shown in Fig.2.

Fig.2. Proposed Circuit diagram of the Buck-boost

converter fed BLDC.

A. Operation during Positive and Negative Half Cycle of

Supply Voltage

In this mode converter switches Sw1 and Sw2 are work in

positive and negative half cycle of supply voltage

individually. Amid positive half cycle switch SW1, inductor

Li1 and diodes D1and D2are worked to exchange vitality to

DC join capacitor Cd. Thus in negative half cycle of supply

voltage switches Sw2, inductor Li2 and diode D2in

Discontinuous Inductor Current Mode (DICM) operation

of converter the present in the inductor Li gets to be

discontinuous for certain term in an exchanging period.

B. Operation During Complete Switching Cycle

In this exchanging cycle there are three methods of

operation.

ModeI: In this mode, switch Sw1 conducts for charging

the inductor Li1, thus the inductor current iLi1 increments

in this mode. Diode Dp finishes the information side

and the DC join capacitor Cd is released by VSI

nourished BLDC motor as shown in Fig.3.

Fig.3.Mode I operation.

Mode II: In this mode of operation switch Sw1 is killed

furthermore, the put away vitality from the inductor Li1

is exchanged to DC join capacitor Cd till the inductor

is completely released furthermore, current in the

inductor is completely lessened to zero as shown in Fig.4.

Fig.4. ModeII operation.

Mode III: In this method of operation inductor Li1 work in

intermittent conduction mode and diodes and switch are in

off condition. As of now DC join capacitor Cd begins

releasing. This operation can be proceeding up to switch

Sw1is turned on once more as shown in Fig.5.

Bridgeless Buck–Boost Converter-Fed BLDC Motor Drive with Fuzzy Based Power Factor Correction



Fig.5. Mode III operation.

Fig.6. Waveforms for positive and negative half cycles of

supply voltage.

Similarly, for the negative half cycle of the supply voltage,

switchSw2, inductor Li2, and diodes DnandD2operate for

voltage control and PFC operation as shown in Fig.6.

III. PROPOSED FUZZY LOGIC CONTROLLER

The control framework is in light of fuzzy logic. FL

controller is an one sort non straight controller and

programmed. This kind of the control drawing closer

the human thinking that makes the utilization of the

acknowledgement, vulnerability,imprecision and fuzzinessin

the choice making procedure, figures out how to offer an

exceptionally tasteful execution, without the need of a

definite numerical model of the framework, just by

fusing the specialists' learning into the fuzzy. Fig.7

demonstrates the FL controller piece outline. This fuzzy

rationale control framework is in view of the MAMDHANI

fuzzy model. This framework comprises of four principle

parts. To begin with, by utilizing the info enrollment

capacities, inputs are Fuzzified then in view of standard

bases and the inferencing framework, yields are delivered

lastly the fuzzy yields are Defuzzified and they are

connected to the principle control framework.

Fig.7.Proposed circuit diagram BL Buck-Boost converter

& BLDC motor with fuzzy controller.

Error of inputs from their references and error deviations

in any time interval are chosen as MATLAB. The output

of fuzzy controller is the value that should be added to

the prior output to produce new reference output.

IV. FUZZY LOGIC CONTROL

L. A. Zadeh presented the first paper on fuzzy set theory in

1965. Since then, a new language was developed to describe

the fuzzy properties of reality, which are very difficult and

sometime even impossible tobe described using conventional

methods. Fuzzy set theory has been widely used in the

control area with some application to power system. A

simple fuzzy logic control is built up by a group of rules

based on the human knowledge of system behavior.

Matlab/Simulink simulation model is built to study the

dynamic behavior of converter. Furthermore, design of fuzzy

logic controller can provide desirable both small signal and

large signal dynamic performance at same time, which is not

possible with linear control technique. Thus, fuzzy logic

controller has been potential ability to improve the

robustness of compensator. The basic scheme of a fuzzy

logic controller is shown in Fig. 8 and consists of four

principal components such as: a fuzzification interface,

which converts input data into suitable linguistic values; a

knowledge base, which consists of a data base with the

necessary linguistic definitions and the control rule set; a

decision-making logic which, simulating a human decision

process, infer the fuzzy control action from the knowledge of

the control rules and linguistic variable definitions; a de-

fuzzification interface which yields non fuzzy control action

from an inferred fuzzy control action [10].




FUZZYFICATION DECISION MAKING DEFUUZZYFICATION

D(k)=d(k-i)+di(k)

De(k)=e(k)-e(k-i)

KNOWLEDGE

Rule Base Data Base

FLC

Error Amplifier

Crisp Value

Real

Input e(k)

Real Di(k)

Vdc_actual

Vdc_ref

Fuzzy µ(k)

Fuzzy µ(e)

Fig.8. Block diagram of the Fuzzy Logic Controller

(FLC) for proposed converter.

Fig.9. Membership functions for Input, Change in input,

Output.

Rule Base: The elements of this rule base table are

determined based on the theory that in the transient state,

large errors need coarse control, which requires coarse in-

put/output variables; in the steady state, small errors need

fine control, which requires fine input/output variables as

shown in Fig.9. Based on this the elements of the rule table

are obtained as shown in Table I, with „Vdc‟ and „Vdc-ref‟ as

inputs.

TABLE I: Rule Table For Fuzzy Controller

V. MATLAB/SIMULINK RESULTS

Here simulation results presented for (i)BLDC drive with

bridgeless buck boost converter with PI controller and

(ii)BLDC drive with bridgeless buck boost converter with

fuzzy controller and results as shown in Figs.10 to 24.

CaseI: BLDC Drive with Bridgeless Buck Boost

Converter with PI Controller

Fig.10.Simulink circuit for proposed BLDC drive with

bridgeless buck boost converter.

Fig.11.Simulation results for source voltage, current, dc

link voltage, and speed, torque, stator current of BLDC

motor under steady state performance with PI controller.




Fig.12.Simulation results for iLi1, iLi2, Vsw1, isw1, Vsw2, isw2

of PFC converter under steady state performance.

Fig.13.Simulation result of proposed system under

dynamic performance during starting condition.

Fig.14. Simulation result of dynamic performance of

proposed system during Speed control condition.

Fig.15.Simulation result of dynamic performance of

proposed system during supply voltage variation.




Fig.16. Power factor With PI controller.

CaseII: BLDC Drive With Bridgeless Buck Boost

Converter With Fuzzy Controller

Fig.17.Simulink circuit for proposed system by using

fuzzy controller.

Fig.18. Simulation results for source voltage, current, dc

link voltage, and speed , torque, stator current of BLDC

motor under steady state performance with fuzzy logic

controller.

Fig.19.Simulation results for iLi1, iLi2, Vsw1, isw1, Vsw2, isw2

of PFC converter under steady state performance with

fuzzy logic controller.

Fig.20. Power factor With fuzzy logic controller.

Fig.21.FFT analysis by using PI controller at 50V dc ref

voltage.




Fig.22.FFT analysis by using fuzzy controllerat 50V dc

ref voltage.

Fig.23.FFT analysis by using PI controller at 200V dc ref

voltage.

Fig.24.FFT analysis by using fuzzy controller at 200V dc

ref voltage.

VI. CONCLUSION

The dynamic characteristics of the brushless DC motor

such as speed, torque, current and voltage of the

inverter components are observed and analyzed using

the developed MATLAB model . Proposed fuzzy logic

controller system has a good adaptability and strong

robustness whenever the system is disturbed. The

simulation model which is implemented in a modular

manner under MATLAB environment allows dynamic

characteristics such as phase currents, rotor speed, and

mechanical torque to be effectively considered . Finally, a

best suited mode of Buck-Boost converter with output

inductor current operating inDICM has been selected for

experimental verifications. The proposed drive system has

shown satisfactory results in allaspects and is a

recommended solution for low power BLDCmotor drives.

VII.REFERENCES

[1]VashistBist and Bhim Singh 2014.An Adjustable-Speed

PFC Bridgeless Buck–BoostConverter-Fed BLDC Motor

Drive . IEEE transactions on industrial electronics, vol. 61,

no. 6, june 2014.

[2]G. Sakthival, T.S. Anandhi and S.P. Natarjan. 2010.

Real time imp lementation of DSP based Fuzzy logic

controller for Speed control of BLDC motor. International

Journal of Co mputer Applications (0975 - 8887). 10(8).

[3]K. Naga Su jatha, K. Vaisakh and Anand. G. 2010.

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motor. IEEE 978- 1- 4244- 6551-4/10 2003. AN885 -

Brushless DC (BLDC) Motor Fundamentals. Microchip

Technology Inc.

[4]R. Akkaya, A.A. Kulaksız, and O Aydogdu, DSP

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Author’s Profile:

B.V.P.Chaitanya received, B.Tech degree

in Electrical and Electronics Engineering

through Gudlavalleeru Engineering College

in 2009. He is now pursuing his M.Tech

(Power Systems) in Guntur Engineering

College. His areas of interest are Power

Electronics Control of Drives, Electrical

Machines, Power Systemsand PLC‟s.

Mr. AfrozShaikis now working as

Assistant Professor in Electrical &

Electronics Engineering Department in

Guntur Engineering College. He received

his M.Tech degree through Nimra College

of Engineering And Technology in 2012.

He is having an experience of 5 years in teaching. He

received his B.Tech degree through RVR&JC College of

Engineering in 2009. His areas of interest are Power

Electronic Control of Drives, Advanced Technologies in

Transmission and Distribution Systems, Electrical Machines.

bridgeless buck boost converter-fed bldc motor drive with

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