ITSI Transactions on Electrical and Electronics Engineering (ITSI-TEEE)
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Soft-Switching Bidirectional Isolated Full-Bridge Converter with
Delicate Exchanging Methods for Battery Energy Storage System
1
R.Tagore Yadav, 2Murali Dasari, 3S.Sridhar
1,2,3
Department of EEE, Geethanjali Institute of Science & Technology, SPSR Nellore, AP, INDIA
Abstract: Separated bidirectional converter with fragile
trading with high change proportion, high yield force, and
delicate start-up ability is proposed in this paper. The
utilization of a capacitor, a diode, and a flyback converter
can clasp the voltage spike brought about by the present
distinction between the current-encouraged inductor and
spillage inductance of the detachment transformer, and
can lessen the present coursing through the dynamic
switches at the current-sustained side. Operational rule of
the proposed converter is initially portrayed, and after
that, the outline comparison is determined. A 1.5- kW
model with low-side voltage of 48 V and high-side voltage
of 360 V has been actualized, from which exploratory
results have checked its attainability.
Key words: Bidirectional converter, high conversion ratio,
coupled-inductor.
I. INTRODUCTION
IN RENEWABLE dc-supply systems, batteries are
reliably expected to move down power for electronic
outfit. Their voltage levels are typically much lower than
the dc-transport voltage. Bidirectional converters for
charging/discharging the batteries are thusly required.
For high-control applications, framework sort
bidirectional converters have transform into a basic
examination subject over the earlier decade [1]–[7]. For
raising power level, a twofold full-unite plan is for the
most part gotten [8]–[16], and its low side and high side
are typically planned with bolster sort and buck-sort
typologies, separately. The huge concerns of these
studies join reducing trade mishap, lessening voltage
and current weights, and diminishing conduction
adversity in light of the fact that obviously current. A
more extreme issue is a direct result of spillage
inductance of the withdrawal transformer, which will
realize high voltage spike in the midst of trading move.
Additionally, the present freewheeling as a result of the
spillage inductance will grow conduction incident and
reduce convincing commitment cycle. An alternative
methodology [9] is to empower the spillage inductance
to raise its available level up to that of the currentmaintained inductor, which can reduce their present
difference and, therefore, diminish voltage spike.
Regardless. Scattered on the resistor, thus achieving
lower viability buck converter was used to supplant a
RCD inert snubber, yet notwithstanding all that it needs
complex catching circuits [17], [18]. An immediate
component propping circuit was proposed [12], [19],
which suits for bidirectional converters. Then again, its
full present extends the present weight on switches
basically. In [20], Wang et al. proposed a topology to
finish fragile starting capacity, regardless it is not
suitable for attempt down operation.
The flyback snubber can reuse the held imperativeness
which is set away in the propping capacitor CC, while
without current traveling through the guideline switches.
It can in like manner clasp the voltage to a fancied
regard just barely higher than the voltage over the low
side transformer. Since the snubber current does not
course through the guideline switches, current tension
can be reduced significantly under generous weight
condition. In addition, the flyback snubber can be
controlled to precharge the high-side capacitor to stay
away from in-surge current in the midst of a start-up
period. In any case, the low- and high-side switches are
worked with hard trading side street, achieving highvoltage spikes.
To handle the already expressed issue, we first present
two bolster capacitors (Cb1 and Cb2) related in parallel
with the upper legs of the voltage-fed augmentation, as
showed in Fig. With these two cushion capacitors, the
low- and high-side switches can work with very nearly
zero-voltage trading (ZVS) and zero present trading
(ZCS). Regardless, when it is worked in venture down
change, these capacitors will resonate with spillage
inductance of the transformer, making EMI upheaval
and growing trading hardship. In this way, two isolates
capacitor–diode snubbers are proposed to supplement
the element flyback snubber, as exhibited in Fig. . The
proposed snubber configuration can't simply reduce the
voltage spike brought on by the present difference
between the spillage inductance and current-managed
inductor streams in any case, also can mitigate the
drawbacks of high-present and high-voltage pesters
obliged on the standard switches at both turn-on and side
street moves. Moreover, it can fulfill close ZVS and
ZCS for the switches on both sides of the transform.
Fig. 1. Proposed soft-switching bidirectional isolated
full-bridge converter with an active flyback and two
passive capacitor–diode snubbers.
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II. CONFIGURATION AND OPERATION
The proposed sensitive trading bidirectional isolated full
platform converter with an element flyback and two idle
capacitor–diode snubbers is demonstrated in Fig. 4. It
can be worked with two sorts of changes: wander up
change and wander down change. Fig. contains a
current-reinforced switch join, an element flyback
snubber at the low-voltage side, a voltage-supported
switch platform, and a dormant snubber pair at the highvoltage side. Inductor Lm performs yield filtering when
power stream from the high-voltage side to the lowvoltage side, which is implied as a stage down change.
Of course, it satisfies desires in the movement up
change. Also, snubber capacitor CC and diode DC are
used to hold the present qualification between currentmanaged inductor current iL and spillage inductance
current iP of separation transformer TP in the midst of
trading reward.
The flyback snubber is attempted to trade the
imperativeness set away in snubber capacitor CC to
support capacitors Cb1 and Cb2, and voltage VC can
drop to zero. Thusly, the voltage weights of switches M1
~ M4 can be obliged to a lower level, achieving close
ZCS side street. The central advantages of the proposed
snubber join no spike current hovering through the
switches and finishing fragile trading components. Note
that high spike current can achieve charge development,
over current thickness, and extra alluring force which
will go to pieces in MOSFET transporter thickness,
channel width, and wire holding and, hence,
manufacture its conduction resistance.
In the movement up change, switchesM1 ~ M4 are
controlled, and the body diodes of switches M5 ~ M8
serve as a rectifier. In the movement down change,
switches M5 ~ M8 are controlled, and the body diodes
of switches M1 ~ M4 fill in as a full-unite rectifier. To
adjust the steady state examination, a couple of
suspicions are made as takes after.
1) All parts are immaculate except for that the
transformer is joined with spillage inductance.
2) Inductor Lm is adequately broad to keep the current
IL reliable more than a trading period.
3) Snubber capacitor CC is much greater than the
parasitic capacitance of switches M1 ∼ M8.
1 Step-Up Conversion:
Exactly when switch sets (M1, M2) and (M3, M4) are
changed to (M1, M4) or (M2, M3), current refinement
iC (= iL − iP) will charge capacitor CC until iP rises to
iL, and capacitor voltage VC will be clamped to VHV •
(NP/NS), finishing close ZCS side street for M2 or M4.
In the interim, high-side current iS has the need
traveling through one of the two inactive capacitor–
diode snubbers, and either Cb1 or Cb2 will be totally
discharged before diode D5 or D7 conducts. Right when
switch pair (M1,M4) or (M2,M3) is changed back to
(M1,M2) and (M3,M4), switch M2 or M4 can have
close ZCS turn-on highlight in light of spillage
inductance Lll limiting the di/dt of high-side diodereverse-recovery current. The flyback snubber works in
the meantime to discharge snubber capacitor CC and
trade the set away imperativeness to bolster capacitors
Cb1 and Cb2. With the flyback snubber, the
essentialness expended in CC won't course through
switches M1 ~ M4, which can decrease their present
bothers altogether when the spillage inductance of the
detachment transformer is vital.
The key voltage and current waveforms of the converter
worked in the movement up change are shown in Fig.2.
A point by point depiction of the converter operation
more than a half trading cycle is displayed as takes after.
Mode 1 [t0 ≤ t < t1]:
Before t0, most of the four switches M1 ~ M4 are turned
on. Inductor Lm is charged by VLV. At t0, M1 and M4
stay driving, while M2 and M3 are murdered. By then,
clamping diode DC conducts, and snubber capacitor CC
is charged by the present differentiation iC. In this
mode, the flyback snubber still stays in the OFF state.
The tantamount circuit is demonstrated in Fig. 3(a).
Mode 2 [t1 ≤ t < t2]:
In this mode, spillage inductance current iP will start to
track current iL, and support capacitor Cb1 will start to
release essentialness. At time t2, current iP is equal to
current iL, the voltage of switches M2 and M3 and
capacitor CC will accomplish the best regard at the same
time, and its proportionate circuit is exhibited in Fig. 3
(b) A nearby ZCS sensitive trading is likewise fulfilled
in the midst of t0 to t2.
Mode 3 [t2 ≤ t < t3]:
Before t3, the essentialness set away in bolster capacitor
Cb1 is not totally discharged yet. Appropriately, the
capacitor won't stop discharging until Vb1 drops to zero.
The equivalent circuit is shown in Fig. 3(c).
In the movement up change, switches M1 ~ M4 are
worked like a help converter, where switch sets (M1,
M2) and (M3, M4) conduct to store essentialness in Lm.
At the high-voltage side, body diodes D5 ~ D8 of
switchesM5 ~ M8 will direct to trade vitality to CHV.
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discharging time of capacitor CC. The expectation is to
ensure that the essentialness set away in capacitor CC
can be completely released, making a ZCS operational
open entryway for switch M2 or M4 at the
accompanying side street move. The equivalent circuit is
exhibited in Fig. 3(f).
Mode 7 [t6 ≤ t < t7]:
At t6, the imperativeness set away in the charging
inductance of transformer TS was completely traded to
support capacitor Cb1, and the circuit operation is
indistinct to a standard turn-on state of a normal
Fig.2. Key voltage and current waveforms of the
proposed converter operated in the step-up conversion.
Mode 4 [t3 ≤ t < t4]:
Right when the essentialness set away in Cb1 has been
completely released to the yield at t3, diode D5 will
coordinate. The circuit operation over this time interval
is vague to a general side street state of a common
current-reinforced full-unite converter. The relative
circuit is shown in Fig. 3(d).
Mode 5 [t4 ≤ t < t5]:
At t4, most of the four switches M1 ~ M4 are turned on
afresh, and switch MS of the flyback snubber is turned
on synchronously. SwitchesM2 andM3 finish a ZCS
turn-on fragile changing component on account of Lll,
and current iP drops to zero consistently. In the flyback
snubber, the essentialness set away in capacitor CC will
be passed on to the polarizing inductance of transformer
TS. The equivalent circuit is shown in Fig. 3(e).
Mode 6 [t5 ≤ t < t6]:
Right when switch MS is slaughtered at t5, capacitor
voltage VC drops to zero, and the essentialness set away
in the charging inductance will be traded to support
capacitor Cb1. In this mode, the time break of driving
sign Vgs(Ms) is insignificantly more than the
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The key voltage and current waveforms of the converter
worked in the movement down change are shown in Fig.
7. A positive depiction of its operation more than a halftrading cycle is shown as takes after.
Mode 1 [t0 ≤ t < t1]:
Fig.3. Operation modes of the step-up conversion (a)
Mode 1 (b) Mode 2# (c) Mode 3 (d) Mode 4 (e) Mode 5
(f) Mode 6 (g) Mode 7
current-reinforced converter. Its indistinguishable circuit
is shown in Fig. 3(g). The circuit operation stops at t7
and completions a half-trading cycle.
In this mode, switchesM5 andM8 are turned on,
whileM6 andM7 are in the OFF state. The high-side
voltage VHV is crossing the transformer, and it is, to be
completely frank, crossing the equivalent inductance
L*eq and drives current iS to rise with the inclination of
VHV/L*eq. With the transformer current extending
toward the store current level at t1, the body diodes (D1
and D4) are prompting trade power and the voltage over
the transformer terminals on the low-voltage side
changes quickly to reflect the voltage from the highvoltage side. The equivalent circuit is exhibited in
Fig.5(a)
Mode 2 [t1 ≤ t < t2]:
At t1, switchM8 stays driving, while M5 is executed.
The body diode of M6 then starts coordinating the
freewheeling spillage current. The transformer current iS
accomplishes the load current level at t1, and VAB
climbs to the reflected voltage (VHV • NP/NS). Cutting
diode DC starts driving the full current of L*eq and the
parasitic capacitance ofM1 ∼ M4. At
Fig.4. Key voltage and current waveforms of the
proposed converter operated in the step-down
conversion.
2. Step-Down Conversion:
In the examination, the spillage inductance of the
transformer at the low-voltage side is reflected to the
high-voltage side in which proportionate inductance
L*eq levels with (Llh + Lll • N2s/N2p).
In the movement down change, switches M5 ∼ M8 are
worked like a buck converter in which switch sets (M5,
M8) and (M6, M7) exchange guiding to trade power
from capacitor CHV to battery BLV. For decreasing
spillage inductance affect on voltage spike, switches M5
~ M8 are worked with stage development control,
fulfilling ZVS turn-on segments. Yet there is no
convincing motivation to hold the present complexity
amidst iL and iP , capacitor CC can help snap the
voltage ringing in view of L*eq and the parasitic
capacitance of M1 ∼ M4. With the two unapproachable
capacitor–diode snubbers, switches M6 and M8 can
perform close ZCS side street.
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Diode ratings:
R_ON=0.001 Ohm
Vfd=0.8V
Snubber: Rs=500 Ohm; Cs=250nF
Flyback transformer ratings:
100VA 50Hz
n=1/ 4.25
Fig.8. Operation methods of the progression down
change (a)Mode 1 (b)Mode 2 (c) Mode 3 (d) Mode 4 (e)
Mode 5
Winding-1: R=4.3 Ohm, L1=0.4H
Windinf-2: R=0.793 Ohm, L2=0.08H
the same time, switch MS of the flyback snubber is
turned on and starts trading the imperativeness set away
in capacitor CC to support capacitors Cb1 and Cb2. The
technique closes at t2 when the resonation encounters a
half resonating cycle and is blocked by securing diode
DC. With the flyback snubber, the voltage of capacitor
CC will be cut to a needed level just fairly higher than
the voltage of Vds(M4). The corresponding circuit is
shown in Fig. 5(b).
Rm=1Mohm; Lm=2866H
Mode 3 [t2 ≤ t < t3]:
Winding-1 : 50V, R1=4.3 Ohm, L1=0.45H
At t2, the body diode of switchM6 is coordinating, and
switchM6 can be turned on with ZVS. The
indistinguishable circuit is shown in Fig. 5(c)
Winding-2: 150V, R2=0.793 Ohm, L2=0.084H
Mode 4 [t3 ≤ t < t4]:
At t3, switch M6 stays coordinating, while M8 is
slaughtered. Support capacitor Cb2 is discharging by the
freewheeling current. Exactly when Cb2 is totally
discharged, a nearby ZCS side street condition is hence
accomplished, and the body diode ofM7 then starts
driving the freewheeling current. The corresponding
circuit is demonstrated in Fig. 5(d).
Active snubber prameters :
Li=500uH
Cc=100nF
Three Winding Transformer
100VA, 50Hz
Winding-3: 150V, R3=0.793 Ohm, L3=0.084H
Turns ration , n=1:3
IV. WAVEFORMS AND CALCULATIONS
1.
INPUT VOLTAGE
Vin=48V
Mode 5 [t4 ≤ t < t5]:
At t4, with the body diode of switch M7 coordinating,
M7 can be turned on with ZVS. Over this time interval,
the dynamic changes change to the following pair of
switches, and the voltage over the transformer pivots its
limit. The circuit operation stops at t5 and completions a
half-trading cycle. The corresponding circuit is shown in
Fig. 5(e).
2.
OUTPUT VOLTAGE
Vout=100V
III SIMULATION PARAMETERS
Simulation is performed using MATLAB/SIMULINK
software. Simulink liabrary files include inbuilt models
of many electrical and electronics components and
devices such as diodes, MOSFETS, capacitors, power
supplies and so on. The circuit components are
connected as per design without error, parameters of all
components are configured as per requirement and
simulation is performed.
DC input voltage=48V
This high voltage at output side is due to step up
operation of the converter circuit
Source side inductance Lm=500uH
Conversion ratio Calculation :
Capacitance Cc=100nF
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DC converter with variable input voltage,” IEEE
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The step up conversion ration in case-a of proposed
converter system is the ratio of output voltage to input
voltage.
Voltage step up gain, G= Vo/Vi
[2]
D. V. Ghodke, K. Chatterjee, and B. G.
Fernandes, “Modified soft switched three-phase
three-level DC–DC converter for high-power
applications having extended duty cycle range,”
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[3]
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pp. 4058–4061.
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signal analysis of a dual half bridge isolated ZVS
bi-directional DC–DC converter for electrical
vehicle applications,” in Proc. IEEE Power
Electron. Spec. Conf., 2005, pp. 2777–2782.
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L.-S. Yang and T.-J. Liang, “Analysis and
implementation of a novel bidirectional DC–DC
converter,” IEEE Trans. Ind. Electron., vol. 59,
no. 1, pp. 422–434, Jan. 2012
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D. Liu and H. Li, “Design and implementation of
a DSP based digital controller for a dual half
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in Proc. IEEE Appl. Power Electron. Conf., 2006,
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Here,
Vo=100V
Vin=48V
Therefore, G=100/48
=2.08
3.
BATTERY PARAMETERS
a)
State of charge(%SOC):
b)
c)
Charging current
Charging Voltage
V. CONCLUSION
A high gain converter with inherent soft-switching
capability is studied. Here voltage with high step up
gain is obtained with this circuit is used to charge up the
super capacity lead-acid batteries. These batteries after
charged, can be used as backup in the substations for
proper relay operations or can be used in automobile
driving applications.
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