IAETSD

1. Fuel cell based Single-InputMultiple-Output DC–
DC Converter for BLDC Motor
G.HARITHA
PG Scholar
Department of Electrical &Electronics Engineering,
Gudlavalleru Engineering College, JNTU K
Gudlavalleru, A.P, India.
e-mail: gangaharitha23@gmail.com
K.BHAVYA
Assistant Professor
Department of Electrical & Electronics Engineering,
Gudlavalleru Engineering college, JNTU K
Gudlavalleru, A.P, India.
e-mail: bhavya.eee.08@gmail.com
Abstract: Brushless dc motors have only a lot of history.
They are used in various industrial and household
appliance manufacturers because of its high efficiency,
low maintenance cost, silent operation, compact form,
and reliability. The aim of this project is to develop fuel
cell based single input multiple output DC-DC converter
for BLDC drive. The proposed converter can boost the
voltage of a low voltage input power source to a
controllable high voltage dc bus and middle voltage
output terminals. In this paper fuel cell connected as
input and total converter connected to BLDC drive.
The high-voltage dc bus can take as the main power for
a high-voltage dc load or the front terminal of a dc-ac
inverter. Moreover, middle-voltage output terminals can
supply powers for individual middle-voltage dc loads or
for charging auxiliary power sources (e.g., battery
modules). In this paper, a coupled-inductor-based dc-
dc converter scheme utilizes only one power switch with
the properties of voltage clamping and soft switching
techniques. The proposed topology will be developed by
using MATLAB/ SIMULINK and simulation results will
be presented.
Index Terms—Coupled inductor, single-input multiple-output
(SIMO) converter, soft switching, voltage clamping, fuel cell,
BLDC motor.
I. INTRODUCTION
DC-DC converters are used in many applications.
Boost converter is used to increase the voltage level of the
input voltage. Normal boost converter has single input
single output but obtain the various voltage levels to
combine the various single input single output DC-DC
converters with different voltage gains but control is
complicated. The existing system of the converter
generating buck, boost and inverted outputs [8] at a time
but over three switches are used for one output is required.
It is only suitable for low voltage and low power
applications.
Nami [9] is proposed DC-DC multi output boost
converter but two switches are required for one output and
control is complex. After to propose a multiple output DC-
DC converter with shared ZCS lagging leg.[10] It is used
to full bridge converters so cost is high.
Finally to propose single input multiple output
converter with coupled inductor [1]. It uses only single
switch and to obtain the different output voltage levels.
Soft switching and voltage clamping techniques are used to
reduce switching and conduction losses.
In this paper fuel cell is used as the input so to
eliminate the environment pollution [2]-[7]. Fuel cell is a
device; it converts chemical energy into electricity through
a chemical reaction with oxidizing agent or oxygen. Fuel
cell has many applications. They are used in automobiles,
airplanes, boats, submarines and hybrid vehicles.
II. PROPOSED CONVERTER
The proposed system can generate two different
voltage levels shown in fig 1. It has five parts, they are low
voltage side circuit (LVSC), clamped circuit, auxiliary circuit,
middle voltage circuit and high voltage side circuit (HVSC).
Equivalent circuit is shown in fig 2. It is used to define the
polarities of voltages and direction of currents. The turns ratio
N and coupling coefficient k of this ideal transformer is
= ⁄
=
( + )
Fig 1: single input multiple outputs DC-DC converter (SIMO)
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International Association Of Engineering & Technology For Skill Development
ISBN : 978 - 1502851550
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2. The coupling coefficient effect is less on the voltage gain and
capacitor c1 is selected to a completely absorb the leakage
energy [11]. The characteristic waveforms are shown in fig 3.
Fig 2: Equivalent circuit
III. MODES OF OPERATION
Mode 1: ( < < )
In this mode, the switch S1 is turned on. At the
time diode D4 was turned off because coupled inductor
winding polarity is positive, the diodeD3 turns on.
Middle voltage capacitor C2 charges and secondary current
reverses. At the end of this mode auxiliary inductor
releases its stored energy and the diode D2 turns off.
Mode 2: ( < < )
At time t=t1, the switch S1 is turned on during this
mode because the primary inductor is charged by the
input power source. In this way secondary voltage
charges the middle voltage capacitor C2 through the
diode D3. At mode 1 and 2
is equal to the input
voltage.
=
= =
=
Mode 3: ( < < )
At time t=t2, the switch S1 is turned off. The
voltage across the switch is higher than the voltage
across the clamped capacitor then diode D1 conducts. At
that time the primary side leakage inductor Lkp partial
energy is transmitted to the Laux, the diode D2 conducts.
When the leakage energy of the secondary side of the
coupled inductor releases completely then the diode D3
turns off.
Apply KVL
+ (1 − ) = 0
= [− /(1 − )]
= − = [ /(1 − )]
Mode 4: ( < < )
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International Association Of Engineering & Technology For Skill Development
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3. In this mode at t=t3, switch S1 is turned off.
Primary side of the coupled inductor leakage energy is
released then flows through the diode D4 to the HVSC. In
this time the current passes through the diode D2 to
output load in the auxiliary circuit.
= + + −
Mode 5: ( < < )
At t=t4, the switch S1 is turned off and diode D1 is
off because primary leakage current equals to the
current of auxiliary inductor. In this time, input source,
primary winding of the coupled inductor and auxiliary
inductor connect in series to supply the power for auxiliary
circuit through diode D2. At that time, secondary winding
of the coupled inductor, clamped capacitor C1 and C2
connect in series to release the energy in to the HVSC
through the diode D4.
+ (1 − ) = 0
Mode 6:( < < )
At t=t5, the switch S1 is on. To select the diode as
a low voltage schottky diode, it will be cut off prompty
without a reverse recovery current. Soft switching is used to
alleviating the switching loss. Remaining is same as the
mode 5.After operation of mode 1 is repeated.
Voltage gain formulas:
= =
+ 1
1 −
= =
1
1 − +
Fig 3: characteristic wave forms of proposed converter
Proceedings of International Conference On Current Innovations In Engineering And Technology
International Association Of Engineering & Technology For Skill Development
ISBN : 978 - 1502851550
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4. IV. SIMULATION RESULTS
The simulation circuit of single input multiple outputs DC-
DC converter is shown in below and to observe the low
power DC to DC converter and high power DC to DC
converter waveforms of voltage and current across the high
voltage side, auxiliary circuit and main switch are shown in
below.
Case-1 Low power DC to DC Converter
Fig.4 Matlab/simulink model of Low power DC to DC converter
Fig.5 Simulated output wave form of the VS1,iS1 in Low power DC
to DC converter
Fig.6 Simulated output wave form of the VD2,iD2 in Low power DC
to DC converter
Fig.7 Simulated output wave form of the VD3,iD3 in Low power DC
to DC converter
Fig.8 Simulated output wave form of the VD4,iD4 in Low power DC
to DC converter
Fig.9 Simulated output wave form of Inductor leakage current in
Low power DC to DC converter
Fig.10 Simulated output wave form of Secondary side current in
Low power DC to DC converter
Fig.11 Simulated output wave form of Inductor auxiliary current in
Low power DC to DC converter
Proceedings of International Conference On Current Innovations In Engineering And Technology
International Association Of Engineering & Technology For Skill Development
ISBN : 978 - 1502851550
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5. Fig.12 Simulated output voltage wave form of the Low power DC
to DC Converter
Case-2 High power DC to DC Converter
Fig.13 Simulated output wave of the Primary side current in High
power DC to DC Converter
Fig.14 Simulated output wave forms of the Secondary side current
in High power DC to DC Converter
Fig.15 Simulated output wave forms of the auxiliary inductor
current in High power DC to DC Converter
Fig.16 Simulated DC output voltage wave form in High power DC
to DC Converter
V. BLDC MOTOR
BLDC motor is one of the popular motor. These
motors are used in industries such as automotive, medical,
aerospace, industrial automation equipment and instrument-
tation. In this motor brushes are not use for the commutation
instead, they are electronically commutated. In this motor
back emf shape is trapezoidal [12]-[13].
Hall sensors are used to sense the rotor position
and to know which winding is energized in energizing
sequence. In this paper, high voltage dc load is connected to
BLDC motor and to observe the performance of BLDC
motor.
Speed torque characteristics:
In continuous operation, motor is loaded up to the
rated torque. In BLDC motor, the torque is remains constant
for a speed range up to rated speed.
Fig 17: speed torque characteristics of BLDC motor
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International Association Of Engineering & Technology For Skill Development
ISBN : 978 - 1502851550
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6. VI. SIMULATION RESULTS
The simulation circuit of single input multiple outputs DC-
DC converter with BLDC motor is shown in fig 10 and to
observe the response of speed and torque are shown in
below.
Fig 18: proposed converter with BLDC motor
Fig 19:input voltage of BLDC motor
Fig 20: stator current and back emf waveforms
Fig 21: speed response of BLDC motor
Fig 22: Torque response of BLDC motor
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International Association Of Engineering & Technology For Skill Development
ISBN : 978 - 1502851550
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7. VII. CONCLUSION
This paper is to develop a single input multiple
output DC-DC converter. Two output terminals are
auxiliary battery module and high voltage dc bus. In this
proposed converter uses only single switch with soft
switching, so to reduce the switching losses. The high
voltage dc bus is connected to the BLDC motor and the
performance of the BLDC motor is observed. The auxiliary
battery module is used to other DC loads.
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Proceedings of International Conference On Current Innovations In Engineering And Technology
International Association Of Engineering & Technology For Skill Development
ISBN : 978 - 1502851550
www.iaetsd.in
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