Download IEEE Transactions on Magnetics

1
Two-phase Boost converter fed DC motor
1
Divyashree.V, 2Ashwini.A, 3Sumathi.S
1
Student, Dept. of EEE, BNM Institute of Technology, Bangalore, India.
2
Assistant Professor, Dept. Of EEE, BNM Institute of Technology, Bangalore, India.
3
Assistant Professor, Dept. Of EEE, BNM Institute of Technology, Bangalore, India.

Abstract--Multi-phasing of dc-dc converters has been
power to an output load and a duty cycle controller for
known to give technical and economic benefits to low
controlling the duty cycle of the power switch. These known
voltage high power buck regulator modules. The major
design commonly allow input current to be split among the
advantage of multi-phasing dc-dc converters is the
phase circuits, thereby increasing the efficiency of the power
improvement of input and output performances in the
converter, in addition, the operation of the phase circuits at
boost converter. The conventional boost converter is
the different phase angles can cancel input ripple current and
cascaded to step-up the voltage to higher level and the
output ripple voltage of the power converters.
first boost stage is multi-phased to avoid high input
current
stress
on
the
switch.
The
multi-phase
Power supplies based on the paralleling a number of
configuration significantly reduces the input current
switching converters offer several advantages over a single
ripple and the output voltage ripple due to the operation
high power centralized power supply, such as low
of the parallel paths and hence reducing the filter size.
component
stresses,
increased
reliability
,ease
of
maintenance and repair, improved thermal management,etc.
Index Terms-- Boost converter, parallel operation of boost
Paralleling of standardized converters will continue to be a
converter, input current ripple, output voltage ripple.
popular approach adopted in distributed power systems for
both front-end and load converters. One basic objective of
I. INTRODUCTION
parallel connected converters is to share the load current
DC to DC converters are widely used in regulated switch
among the constituent converters. A variety of approaches,
mode power supplies, telecommunications and dc motor
with varying complexity and current sharing performance,
drive applications and are extremely important in battery
have been proposed in the past two decades. In general,
powered electronic devices. The electronic devices often
methods for paralleling dc-dc converters are described in
contain several sub-circuits, each requiring a voltage level
terms of connection styles, control configurations and
different than that supplied by the battery. It is always
feedback functions.
desired to produce well regulated output voltage in the
presence of variations in the input voltage and load current
DC-DC converters being widely used, it was much preferred
[5].
to design a dc to dc boost converter with an interleaved or
multiphase technique to meet the higher power demands.
Various multiphase power converters are known having a
This type of circuit is used to ‘step-up’ a source voltage to a
plurality of phase circuits connected in parallel. Typically,
higher regulated voltage, allowing one power supply to
each phase circuits includes a power switch for delivering
provide different driving voltages and meeting the increased
2
power demands. In this work, parallel operation of the boost
an inductor to resist changes in current by creating and
converter
using
destroying a magnetic field. In a boost converter, the output
are
voltage is always higher than the input voltage. A schematic
fed
to
MATLAB/SIMULINK
DC
drive
software
is
and
simulated
the
results
compared with that of conventional boost converter fed to
of a boost power stage is shown in Figure 1.
DC drives. Converter controlled electrical machine drives
are very important in modern industrial applications. The
speed of the DC motor is controlled by controlling DC
voltage across its armature terminals. Hence two phase boost
converters can be used to control the speed of the DC drives.
II. BOOST CONVERTER
A boost converter is simply a particular type of dc to dc
converter with an output DC voltage greater than the input
DC voltage. This type of circuit is used to ‘step-up’ a source
voltage to a higher, regulated voltage, allowing one power
Figure 1. Boost converter
supply to provide different driving voltages. Step up
A. DESIGN EQUATIONS
choppers for DC to DC power conversion find widespread
The duty ratio (D) of a typical boost converter is given by
applications in different areas. However its operation mode
[9]:
and control scheme strongly depend on the specific
D=
--- (1)
application and the available components. This work
presents a detailed design and analysis of the two-phase
boost converter fed DC motor.
Where Vout - output voltage and Vin - input voltage.
The inductor shown in figure 1 can be designed using the
expression:
This is an interesting technique, having the features of
parallel operation, and increased frequency of operation. In
multiphase operation, converters are connected in parallel
and are controlled by interleaved switching signals, which
L=
--- (2)
Where L–Inductance, f–switching frequency and Irippleinductor input ripple current.
The value of capacitance [9] is given by the expression:
have the same switching frequency and the same phase
shifting. The switching instants are sequentially phase
shifted by equal fractions of a switching period. This
C=
--- (3)
Where ∆V- output ripple voltage.
arrangement lowers the net ripple amplitude and raises the
effective ripple frequency of the overall converter without
III. PARALLEL BOOST CONVERTER
increasing switching losses or device stresses. The resulting
Even though the input inductor makes the source current
cancellation of low frequency harmonics allows eventually
smooth the boost converter suffers from the disadvantage of
the reduction of size and losses of the filtering stages. The
discontinuous current injected to the load. The size of the
obvious benefit is an increase in the power density without
capacitor is therefore large. Further, the ripple current in the
the penalty of reduced power conversion efficiency. There is
capacitor is as much as the load current. Hence the ripple
still a penalty of increased circuit complexity [3].The key
current and the ESR specification of the tank capacitor are
principle that drives the boost converter is the tendency of
quite demanding. In standard designs it is uncommon to see
3
tank capacitors one or two orders of magnitude higher than
Figure 3 illustrates the timing signals for the two phases
the ideally required capacitance. A way to overcome this
(switches Q1 and Q2) for the duty cycles 50% and 30%
problem is using parallel operation. Each phase of the
respectively. The frequency multiplication effect is clearly
parallel boost converter works in the same way as that the
shown on the combined Iin waveform as having its period
single phase boost converter does. The two power stages
half that of individual inductor current. One advantage that
operate 180ᵒ out of phase, cancelling the ripple in the input
is not apparent from the figure is the amount of peak to peak
current and output voltage. The inductor current varies twice
ripple on the input current which should be half that of each
in every cycle of the input current. Input voltage varies twice
individual inductor current. This is called the ripple
in every cycle of the input voltage. The duty cycle therefore
cancellation effect in multiphase scheme [4].
varies in the full range of zero to one. The parallel-boost
approach which uses forced current sharing between the
power stage could deliver substantially more power than the
other, which would defeat the ripple cancellation[1].
Figure 2 shows the basic 2-phase boost converter. One
advantage that is evident from the figure is that the
multiphase configuration allows the combination of output
capacitor from each individual boost into just a single
capacitor Co. Due to the frequency multiplication property
of the multiphase, the output voltage will actually have
ripple component twice the operating switching frequency of
each individual boost converter. This may further reduce the
output filtering requirement. The frequency multiplication
effect also occurs at the input side of the boost and hence
reducing the input filtering requirement as well as improving
the quality of the input current. In turns, both input and
output sides of the multiphase boost will emit less dv/dt and
Figure 3: Inductor current waveforms of two phase
boost converter.
di/dt noises back to the system connected to them.
IV. SIMULATION AND RESULTS
The simulation block diagram of the single phase boost
converter fed dc motor is as shown in figure 4. For the given
DC motor, the MOSFET is designed to have a switching
frequency of 25 kHz with 50% duty cycle. The input current
waveform and output voltage waveform of a single phase
boost converter is as shown in figure 5 and figure 6
respectively.
It can be seen from figure 5 that the input ripple current in
Figure 2: Two phase boost converter
the single phase boost converter is 0.5 Amps and from the
4
figure 6 it can be inferred that the output voltage ripple is
output voltage. The inductor current varies from zero to
0.0125Volts.
nominal current twice in every cycle of the input current as
shown in figure 8. The input ripple current and output ripple
voltage in the two phase boost converter is found to be
0.1Amps and 0.001Volts respectively and the corresponding
waveforms are as shown in figure 9 and 10 respectively.
Figure 4: Simulation block diagram of Single phase
boost converter
Figure 7: Simulation block diagram of two phase boost
converter
Figure 5: Input current waveform of single phase boost
converter
Figure 8: Inductor currents in two phase boost converter
Figure 6: Output voltage waveform of single phase boost
converter
The simulation block diagram of two phase boost converter
is as shown in figure 7. The circuit is designed for the same
requirements as that of single phase boost converter shown
in figure 4. But the two power stages operate 180ᵒ out of
Figure 9: Input current waveform of two phase boost
phase, cancelling the ripple in the input current and the
converter
5
Table II
Specifications of Motor and Various Parameters
Armature resistance (Ra)
02.581Ω
Armature inductance(La)
0.028 H
Armature voltage (Va)
240 V
Mechanical inertia (Jm)
0.10225Kg.m2
Friction coefficient (Bm)
0.002953N.m/rad/sec
Rated speed
1750 rpm
Field voltage (Vf)
300 V
Input voltage(Vin)
120V
Duty cycle
50%
L
3.131mH
C
1277.95uF
Figure 10: Output voltage waveform of two phase boost
converter.
Table I
Comparison of Performance of Single Phase Boost
Converter and Two Phase Boost Converter
CONVERTER
SINGLE PHASE
INPUT RIPPLE
OUTPUT RIPPLE
CURRENT
VOLTAGE
(Amperes)
(Volts)
0.5
0.0125
V1.REFERENCES
[1]
R.Mirzaei and V.Ramanarayananm “Polyphase Boost
Converters for automotive and UPF applications”,
BOOST
European
CONVERTER
Power
Electronic
Conference,
Dresden,
Germany, September 2005.
TWO PHASE
0.1
0.001
[2]
BOOST
Dodi Garinto, “New converter architecture with multiinterleaving technique for future microprocessors.”IEEE
CONVERTER
INTELEC 2006.
V.CONCLUSION
[3]
Marcos
Prudente,
Luciano
L.
Pfitscher,
Gustavo
Parallel boost converters are used in high power applications
Emmendoerfer, Eduardo F. Romaneli, and Roger Gules,
where it is not possible to obtain the required power level
“Voltage Multiplier Cells Applied to Non Isolated DC–
with a single stage converter. There are two advantages of
DC Converters,” IEEE TRANSACTIONS ON POWER
multi-phase or interleaving technique. The first point lies in
ELECTRONICS, VOL. 23, NO. 2, MARCH 2008
the parallel architecture, which allows higher power
[4]
Taufik, Tadeus Gunawan, Dale Dolan and Makbul
operation, and the second point is increasing the net
Anwari ,“Design and Analysis of Two-Phase Boost DC-
operating frequency in input/output of the system without
DC Converter “, International Science Index Vol:4, No:7,
increasing the switching frequency. By paralleling the
2010 waset.org/Publication/9970.
converter, characteristics such as maintenance, repair, loss-
[5]
J. Chen, D. Maksimovi´c, and R. W. Erickson, “Analysis
heat dissipation, reliability and fault tolerance are improved.
and design of a low-stress Buck-Boost Converter in
Thus parallel boost topology provides superior performance
Universal-Input PFC Applications,” IEEE Trans. on
over single phase.
Power Electronics, vol. 21, pp. 320– 329, Mar. 2006.
6
[6]
W. Wen and Y. S. Lee, “A Two-Channel Interleaving
Boost Converter with Reduced Core Loss and Copper
Loss,” IEEE Power Electronic Specialist Conference, pp.
1003–1009, 2004.
[7]
S. Luo, Z. Ye, R. L. Lin, and F. C. Lee, “A Classification
and Evaluation of Paralleling Methods for Power Supply
Modules,” IEEE Power Electronic Specialist Conference,
vol. 2, pp. 901–908, Jun.-Jul. 1999.
[8]
R.
and
Seyezhai
B.L.
Mathur
,“Design
and
implementation of fuel cell based Interleaved Boost
Converter”,
At
the
International
Conference
on
Renewable Energy, University of Rajasthan, Jaipur, ICRE
2011 Jan 17-21, 2011.
[9]
W. Li, Y. Zhao, Y. Deng, and X. He, “Interleaved
converter with voltage multiplier cell for high step-up
and high-efficiency conversion”, Trans. on Power
Electronics IEEE 1, 2397–2408 (2010).