International Journal of Engineering Trends and Technology (IJETT) – Volume 28 Number 4 - October 2015
Controlling of Electronically Commuted Motor Drive Using DC-DC
Cuk Converter
Amit Dodke 1, R.G.Shriwastava2 , K.N.Sawalakhe
M.Tech.student, PEPS, SDCOE, Wardha(M.S.),India
Associate Prof &Head. Elect. Deptt. BDCOE, Sewagram( M.S.),India
Assistant Prof &Head. Elect. Deptt. SDCOE, Wardha(M.S.),India
Abstract- In this paper novel technique of DC-DC cuk
converter fed electronically commutated motor for
controlling the speed explain. A DC-DC converter topology
is employed for speed control and operated with voltage
follower control in discontinuous conduction mode (DCM).
A DC-DC converter is operated with voltage follower control
schemes for the operation of PMBLDCMD under wide
range speed control. MATLAB Simulation is studied to
simulate the model to study a wide range of speed control.
is impractical since the use of semiconductor device will be
very inefficient. Thus the problem has to be solved in a
different way to achieve cost effective Conventional dc
motors are highly efficient and their characteristics make them
suitable for use as servomotors. However, their only drawback
is that they need a commutator and brushes which are subject
to wear and require maintenance. When the functions of
Keywords - BLDC, Cuk Converter, Inverter, PI controller
commutator and brushes were implemented by solid-state
I. INTRODUCTION
The concepts behind converting electrical energy into
switches, maintenance-free motors were realised. These
mechanical energy have been known since the late 1820‟s
DC Motor was quite expensive when first introduced, the
when the first electric motor was successfully tested. British
advancements in design and materials drastically lowered
scientist Michael Faraday first experimented with the idea of
costs and made the Brushless DC Motor a popular selection
the electromagnetic induction motor in the early 1800‟s. By
for many different applications. Brushless DC (BLDC) motors
1828 the DC Motor was introduced with three main
are preferred as small horsepower control motors due to their
components: the stator, rotor, and commutator. During that
high efficiency, silent operation, compact form, reliability,
time, DC Motors operated similar to Brush DC Motors today,
and low maintenance. Being an electronically commutated
in that they had current flowing through the windings of the
motor, the commutation losses in the BLDC motor are
motor. In 1837 Americans Thomas and Emily Davenport
negligible BLDC motor when fed by an uncontrolled bridge
transformed Faraday‟s DC Motor into one that could be used
rectifier with DC link capacitor results in highly distorted
for commercial use. These DC Motors became popular in
supply current which results in low PF (Power Factor) and
printing presses and powered machine tools. However, with
high THD (Total Harmonic Distortion); hence various
the high cost of battery power, the demand was too small to
improved power quality DC-DC converters are used in these
keep them successful. In 1886, Frank Julian Sprague
drives[1]. However, the problems are encountered in these
introduced the first practical DC Motor that was capable of
motor for variable speed operation. Over last decades
constant speed under variable loads With the development of
continuing technology development in power semiconductors,
power electronics device it seemed to be feasible that the
microprocessors, adjustable speed drivers control schemes and
mechanical switching part of a brush type dc motor could be
permanent-magnet brushless electric motor production have
replace by electronic switching. However a simple translation
been combined to enable reliable, cost-effective solution for a
of a brush type motor designed to operate as a brushless type
broad range of adjustable speed applications. As of today
motors are now known as brushless dc motors. The Brushless
there are over 15 types of various DC and Ac motors that all
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International Journal of Engineering Trends and Technology (IJETT) – Volume 28 Number 4 - October 2015
serve the purpose of converting electrical energy into
compared with saw-tooth carrier wave of fixed frequency to
mechanical energy or vice versa. Permanent magnet brushless
generate a pulse width modulated signal for the switching
DC motors (PMBLDCMs) are preferred motors for a
device of the DC-DC converter.
compressor of an air-conditioning system due to its features
For the speed control, the speed signal derived from rotor
like high efficiency, wide speed range and low maintenance
position of the PMBLDCM, sensed using Hall effect sensor, is
requirements. The operation of the compressor with the speed
compared with a reference speed. The resultant speed error is
control results in an improved efficiency of the system while
passed through a speed controller to get the torque equivalent
maintaining the temperature in the air-conditioned zone at the
which is converted to an equivalent current signal using motor
set
torque constant [8].
reference
consistently.
Whereas,
the
existing
air
conditioners mostly have a single-phase induction motor to
This current signal is multiplied with a rectangular unit
drive the compressor in on/off control mode. This results in
template waveform which is in phase with top flat portion of
increased losses due to frequent on/off operation with
motor‟s back EMF so that reference three phase current of the
increased mechanical and electrical stresses on the motor,
motor are generated .These reference current are compared
thereby poor efficiency and reduced life of the motor.
with the sensed motor current and current error are generated
Moreover, the temperature of the air conditioned zone is
which is amplified and compared with triangular carrier
regulated in a hysteresis band. Therefore, improved efficiency
waves to generate the PWM signals for the VSI switches [7].
of the Air-Conditioning system will certainly reduce the cost
MOSFET is use for its high frequency operation whereas
of living and energy demand to cope-up with ever-increasing
an IGBT‟s (Insulated Gate Bipolar Transistor) are used in the
power crisis [2].
VSI for low frequency operation The proposed scheme
maintains high power factor and low THD of the AC source
II. METHODOLOGY
current while controlling rotor speed equal to the set reference
speed. A voltage follower approach is used for the control of
DC-DC converter operating DICM. [2]
. Fig. 1. Block diagram for Cuk converter fed BLDC motor
drive
The proposed buck-boost converter based PMBLDCM drive
operated with voltage follower control. The proposed
controller is operated to maintain a constant DC link voltage
Fig.2.Trapezoidal BLDC motor Fed from VSI
with PFC action at AC mains. The DC link voltage is sensed
and compared with a reference voltage which results in a
voltage error. This voltage error is passed through a voltage
controller to give a modulating signal which is amplified and
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International Journal of Engineering Trends and Technology (IJETT) – Volume 28 Number 4 - October 2015
III. THE ROLE OF HALL EFFECT SENSORS
IV. MODELLING OF THE PROPOSED PMBLDCM DRIVE
Unlike a brushed DC motor, the commutation of a BLDC
The modelling of proposed PMBLDCM drive involves
motor is controlled electronically. To rotate the BLDC motor,
modelling of the PFC converter and PMBLDCM drive. These
the stator windings should be energized in a sequence. It is
components are modelled in the form of mathematical
important to know the rotor position in order to understand
equations and the complete drive is represented as a
which winding will be energized following the energizing
combination of these models.
sequence. Rotor position is sensed using Hall effect sensors
embedded into the stator.
I. PFC CONVERTER
Most BLDC motors have three Hall sensors embedded
into the stator on the non-driving end of the motor. Whenever
the rotor magnetic poles pass near the Hall sensors, they give
a high or low signal, indicating the N or S pole is passing near
The PFC converter consist of a DBR at front end and a buckboost converter with an output ripple filter.The PFC converter
modeling consists of the modeling of a voltage controller and
a PWM controller as a given below.
sensors. Based on the combination of these three Hall sensor
signals, the exact sequence of commutation can be determined.
Commutation feedback devices provide current rotor position
information to the control unit in the form of U, V, and W
a.
Voltage Controller
The voltage controller is a proportional integral (PI) controller
which closely monitors the voltage error and generates control
signals. These feedback devices can also send other
signal (Ic) to minimize the voltage error. If at kth instant of
information to the control unit, e.g., speed, acceleration,
time, V*dc(k) is reference DC link voltage, V dc(k) is sensed
rotational direction, number of revolutions, etc. Hall effect
sensors are the most widely used devices. This cost-effective
sensing system had matured since its introduction in the late
1970s. One of the more recent alternatives is the optical
commutation encoder. This encoder generates precise angular
encoding signals and is often recommended where greater
resolution is desired. This means the commutation tracks of
the code disc need to be aligned to the rotor position.
Magnetic hall effect sensors and optical commutation
encoders are the preferred feedback devices in today‟s
industry, although these encoders have some limitations and
drawbacks.
Hall
sensors
detect
movement
of
the
commutation magnet, while the optical commutation
encoder
senses
movement
of
the
code
wheel.
DC link voltage then the voltage error Ve(k) is calculated as,
Vc(k) = V*dc(k)-Vdc(k)
………..(1)
th
The output of the controller Ic(k) at k instant is given as,
Ic(k) = Ic(k-1) +Kpv {Ve(k)-Ve(k-1)}+KivVe(k)………(2)
Where Kpv and Kiv are the proportional and integral gains of
the voltage PI controller.
b.
PWM Controller
The output of PI controller is amplified by gain kdc and
compared with fixed frequency (fs) saw-tooth carrier
waveform md(t) to get the switching signals for the MOSFET
o the buck-boost PFC converter shown in Fig.3 and given as,
If kdcIc(k) > md(t)
If kdcIc(k) <= md(t)
then S = 1
then S = 0
………..(3)
………..(4)
The
Where S is the switching function representing “ON” position
commutation magnet pole pair and code wheel track patterns
of the MOSFET of the PFC converter with S = 1 and its
are fixed and matched to BLDC rotor pole pairs. This
“OFF” position with S = 0.
prohibits the end user from configuring the commutation
magnet or codewheel pattern when matching up a different
pole pair BLDC motor [8].
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International Journal of Engineering Trends and Technology (IJETT) – Volume 28 Number 4 - October 2015
c.
PWM Current Controller
The current errors
ia,
ib, ic are amplified by gain k1 and
compared with carrier waveform m(t) of a fixed frequency in
the PWM current controller to generate the switching
sequence for the voltage source inverter. The switching
sequence is generated based on the logic given for phase “a”
Fig.3.PWM controller signals of proposed cuk PFC converter
as,
II. PMBLDCM Drive
If k1 ia >m(t) then Sa = 1 („IGBT ON‟) ……….
The PMBLDCM drive has a speed controller, a reference
If k1 ia
winding current generator, a PWM current controller, a
voltage source inverter (VSI) and a PMBLDC motor as the
logic for other two phases of the motor.
d.
reference speed. If at kth instant of time,
reference speed,
e(k)
r(k)
*r(k) is the
is the rotor speed then the speed error
m(t) then Sa = 0 („IGBT OFF‟) ………..(10)
The switching sequence Sb and Sc are generated using similar
main components.
The speed controller is a PI controller which closely tracks the
Voltage Source Inverter
Fig 2. shows an equivalent circuit of a VSI fed PMBLDCM.
The output of VSI to be fed to phase „a‟ of the PMBLDC
motor is given as,
vao= (Vdc/2)
can be calculated as,
=
*r(k) -
………..(5)
r(k)
get desired control signal.
a.
Where, Kp
and Kj
{we(k)-
e(1)}+Kj
e(k)………..(6)
are the proportional and integral gains
link.
Using similar logic vbo, vco, vbn, vcn are generated for other two
phases of the VSI feeding PMBLDC motor. The voltages
van,vbn and vcn are voltages of three phases with respect to the
of the PI speed controller.
b.
……….. (14)
van = va0-vn0
neutral terminal (n) with respect to virtual mid point of the DC
th
The speed controller s output at k instant T(k) is given as,
T(k)=T(k-1)+Kp
……… ..(13)
for Ia =0
Where vao, vbo, vco and vno are voltages of three phases and
Speed controller
‟
……….. (12)
for Sa = 0
*
vao=0
This speed error is processed through the speed controller to
……… ..(11)
for Sa = 1
vao = (-Vdc/2)
e(k)
(9)
motor neutral terminal (n).
Reference Winding Current Generator
The amplitude of stator winding current is calculated as,
I*=T(k)/(2Kb)
………..(7)
Where, Kb is the back emf constant of the PMBLDCM.
V. RESULT
Result obtained cuk converter fed BLDC motor drive are
as follow which show the output voltage , speed of BLDC
motor, electromagnetic torque and stator current.
The reference phase currents of the PMBLDCM are the
PMBLDCM are denoted by ia*,ib*,ic* for phases a, b,c
300
respectively. For duration of 0-60 the reference current can
200
………..(8)
ia* = I*, ib* = -I* and ic* = 0
(ia,ib,ic) to generate the current errors
*
ia=(ia*-ib),
ic=(ic -ic) for three phases of the motor.
ISSN: 2231-5381
ib=(ib*-ib),
Voltage(V)
be given as,
Vo
100
0
-100
0
0.02
0.04
0.06
0.08
0.1
Time (Sec)
0.12
0.14
0.16
0.18
0.2
Fig.4. Output voltage og cuk conveter
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International Journal of Engineering Trends and Technology (IJETT) – Volume 28 Number 4 - October 2015
Rotor speed (rpm)
2000
APPENDIX
Speed (rpm)
1500
1000
BLDC Motor Rating: 4 pole, Prated (Rated Power) =
251.32W, Trated (Rated Torque) = 1.2 Nm, ωrated (Rated
Speed) = 2000 rpm, Kb (Back EMF Constant) = 78 V/krpm,
Kt (Torque Constant) = 0.74 Nm/A, Rph (Phase Resistance)
=14.56Ω, L (Phase Inductance) = 25.71 mH, J (Moment of
Inertia) = 0.00013 kg-cm2.
500
0
-500
0
0.02
0.04
0.06
0.08
0.1
Time (sec)
0.12
0.14
0.16
0.18
0.2
Fig.5. speed of BLDC motor
REFERENCES
[1] Singh, S.; Singh, B., "A Voltage-Controlled PFC Cuk Converter-Based
PMBLDCM Drive for Air Conditioners," Industry Applications, IEEE
Transactions on , vol.48, no.2, pp.832,838, March-April 2012.
[2] Simonetti, D. S L; Sebastian, J.; dos Reis, F.S.; Uceda, J., "Design criteria
for SEPIC and Cuk converters as power factor preregulators in discontinuous
conduction mode," Industrial Electronics, Control, Instrumentation, and
Automation, 1992. Power Electronics and Motion Control., Proceedings of
the 1992 International Conference on, vol., no., pp.283, 288 vol.1, 9-13 Nov
1992.
[3] Singh, B.; Singh, B.N.; Chandra, A; Al-Haddad, K.; Pandey, A; Kothari,
D.P., "A review of single-phase improved power quality AC-DC
converters," Industrial Electronics, IEEE Transactions on, vol.50, no.5,
pp.962, 981, Oct. 2003.
[4] Bist, V.; Singh, B., "An Adjustable-Speed PFC Bridgeless Buck–Boost
Converter-Fed BLDC Motor Drive," Industrial Electronics, IEEE
Transactions on , vol.61, no.6, pp.2665,2677, June 2014.
[5] Singh, S.; Singh, B., "PFC buck converter fed PMBLDCM drive for low
power applications," Power India Conference, 2012 IEEE Fifth , vol., no.,
pp.1,5, 19-22 Dec. 2012 .
[6] Rong-Jong Wai; Kun-Huai Jheng, "High-Efficiency Single-Input
Multiple-Output DC–DC Converter," Power
[7]B.Chandra Krishna, And M. Nageswara Rao, “Speed Control of BLDC
Motor using Modified Buck Boost Converter” IJSETR, Vol. 3, pp. 92849293, Dec 2014.
[8]G. K Dubey, “Fundamental of Electrical Drive”, Narosa Publishing
House, pp.65-66.
[9]Khanchandani and M. D. Singh, “Power Electronics”, Dhanpat Rai
Publication, IInd Edition copyright 2011-12,pp.43.
Stator current ia
6
current
4
2
0
-2
-4
0
0.02
0.04
0.06
0.08
0.1 0.12
Time(sec)
0.14
0.16
0.18
0.2
Fig.6. stator curent
Electromagnetic Torque (Nm)
2.5
Tm
2
1.5
1
0.5
0
0
0.02
0.04
0.06
0.08
0.1
0.12
Time (sec)
0.14
0.16
0.18
0.2
Fig.7.Electromagnetic torque
VI. CONCLUSION
The design, modelling and simulation of cuk converter fed
PMBLDCM drive has been carried out in detail for its with
voltage follower control to get a reduced sensor controller.
Therefore, the non-isolated cuk converter fed PMBLDC
voltage follower control has potential operation under speed
control. The cuk converter is operated for many low cost and
low voltage speed control application operated for utility AC
mains. It is conclude that the proposed drive has best
performance with reduced sensor as a variable speed and
improved power quality at input AC mains.
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