ISSN 2348–2370
Vol.08,Issue.03,
March-2016,
Pages:0505-0512
www.ijatir.org
Bridgeless Buck–Boost Converter-Fed BLDC Motor Drive with Fuzzy
Based Power Factor Correction
B. V. P. CHAITANYA1, AFROZ SHAIK2
1
2
PG Scholar, Dept of EEE, Guntur Engineering College, Yanamadala, Guntur (Dt), AP, India.
Assistant 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
Copyright @ 2016 IJATIR. All rights reserved.
B. V. P. CHAITANYA, AFROZ SHAIK
of the low frequency operation of VSI for the electronic
voltage switches Sw2, inductor Li2 and diode D2in
commutation of the BLDC motor.
Discontinuous Inductor Current Mode (DICM) operation
of converter the present in the inductor L i gets to be
discontinuous for certain term in an exchanging period.
Single
phase AC
mains
LC
filter
BL Buck - Boost
Converter
VSI
BLDC MOTOR
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.
CONTROL UNIT
SAW-TOOTH
GENERATOR
B. Operation During Complete Switching Cycle
In this exchanging cycle there are three methods of
operation.
PWM
GENERATOR
ELECTRONIC
COMMUTATION
VOLTAGE
CONTROLLER
+
REF VOLTAGE
GENERATOR
Fig.1.Block diagram of PFC BL-BUCK
Converter fed BLDC motor drive.
HALL EFFECT
POSITION SENSING
REF SPEED
BOOST
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 BuckBoost 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.3.Mode I operation.
Mode II: In this mode of operation switch Sw1 is killed
furthermore, the put away vitality from the inductor L i1
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.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
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.
International Journal of Advanced Technology and Innovative Research
Volume.08, IssueNo.03, March-2016, Pages: 0505-0512
Bridgeless Buck–Boost Converter-Fed BLDC Motor Drive with Fuzzy Based Power Factor Correction
Fig.5. Mode III operation.
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.
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.
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 defuzzification interface which yields non fuzzy control action
from an inferred fuzzy control action [10].
International Journal of Advanced Technology and Innovative Research
Volume.08, IssueNo.03, March-2016, Pages: 0505-0512
FLC
KNOWLEDGE
Rule Base Data Base
FUZZYFICATION
Fuzzy µ(e)
DECISION MAKING
B. V. P. CHAITANYA, AFROZ SHAIK
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 µ(k)
fuzzy controller and results as shown in Figs.10 to 24.
DEFUUZZYFICATION
CaseI: BLDC Drive with Bridgeless Buck Boost
Converter with PI Controller
Di(k)
Real
D(k)=d(k-i)+di(k)
Real
De(k)=e(k)-e(k-i)
Crisp Value
Input e(k)
Vdc_actual
Vdc_ref
Error Amplifier
Fig.8. Block diagram of the Fuzzy Logic Controller
(FLC) for proposed converter.
Fig.10.Simulink circuit for proposed BLDC drive with
bridgeless buck boost 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 input/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
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.
International Journal of Advanced Technology and Innovative Research
Volume.08, IssueNo.03, March-2016, Pages: 0505-0512
Bridgeless Buck–Boost Converter-Fed BLDC Motor Drive with Fuzzy Based Power Factor Correction
Fig.12.Simulation results for iLi1, iLi2, Vsw1, isw1, Vsw2, isw2
of PFC converter under steady state performance.
Fig.14. Simulation result of dynamic performance of
proposed system during Speed control condition.
Fig.13.Simulation result of proposed system under
dynamic performance during starting condition.
Fig.15.Simulation result of dynamic performance of
proposed system during supply voltage variation.
International Journal of Advanced Technology and Innovative Research
Volume.08, IssueNo.03, March-2016, Pages: 0505-0512
B. V. P. CHAITANYA, AFROZ SHAIK
Fig.16. Power factor With PI controller.
CaseII: BLDC Drive With Bridgeless Buck Boost
Converter With Fuzzy Controller
Fig.19.Simulation results for iLi1, iLi2, Vsw1, isw1, Vsw2, isw2
of PFC converter under steady state performance with
fuzzy logic controller.
Fig.17.Simulink circuit for proposed system by using
fuzzy controller.
Fig.20. Power factor With fuzzy logic 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.21.FFT analysis by using PI controller at 50V dc ref
voltage.
International Journal of Advanced Technology and Innovative Research
Volume.08, IssueNo.03, March-2016, Pages: 0505-0512
Bridgeless Buck–Boost Converter-Fed BLDC Motor Drive with Fuzzy Based Power Factor Correction
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.
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.
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International Journal of Advanced Technology and Innovative Research
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B. V. P. CHAITANYA, AFROZ SHAIK
[11]B. Singh, S. Singh, A. Chandra, and K. Al-Haddad,
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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.
International Journal of Advanced Technology and Innovative Research
Volume.08, IssueNo.03, March-2016, Pages: 0505-0512