ISSN: 2393-994X
KARPAGAM JOURNAL OF ENGINEERING RESEARCH (KJER)
Volume No.: II, Special Issue on IEEE Sponsored International Conference on Intelligent Systems and Control (ISCO’15)
High Voltage-Boosting Converters Using Bootstrap Capacitors and
Boost Inductors
N.Santhipriya1, J.Velmurugan2
1
PG Scholar,Dept of EEE,santhipriya1992@gmail.com, PSNA CET,Dindigul, India
J.Velmurugan,Associate professor,vel_76@yahoo.co.in,PSNA CET,Dindigul,India
2
Abstract
The high-voltage gain converters plays an important role in many industrial applications, such as
photovoltaic systems, fuel cell systems, electric vehicles, and high-intensity discharge lamps. This project
proposes high voltage-boosting converters using bootstrap capacitors and boost inductors. By changing
the connection position of the anode of diode and by using different pulse-width modulation control
strategies, different voltage conversion ratios can be obtained. In this proposed converters there are two
boost inductors with different values, connected in series, can still make the converters work
appropriately. Although there are three switches in each converter, only one half-bridge gate driver and
one low-side gate driver are needed, but no isolated gate driver would be needed. The basic operating
principle of the proposed converters is presented along with some experimental results to demonstrate the
effectiveness of these converters.
Keywords: Boost converter, bootstrap capacitor, pulse-width-modulation (PWM), voltage-boosting converter, voltage
conversion ratio.
1. Introduction
The high step-up converters have been widely used in many applications, such as battery powering device,
uninterruptible power supply, and solar system [2] etc. The solar cell system needs the high voltage-boosting
converter to transfer the low voltage to the high voltage which will be transferred to the ac output voltage via the dcac converter. Such a high voltage-boosting converter consists of the traditional boost or flyback converter. The boost
converter is simple in structure, but the voltage conversion ratio is not so high, whereas the flyback converter
possesses a high voltage conversion ratio but the corresponding leakage inductance is large. A method of improving
the voltage conversion ratio is proposed, and this is based on the fact that the number of inductors is increased, and
these inductors are connected in series during the demagnetizing period, thereby pumping the energy created by the
input voltage and the energy stored in the inductors into the output terminal to obtain high voltage conversion ratio.
The current in each inductor can be considered as a current source. Consequently inductors with different values,
connected in series, imply that current sources with different values are connected in series, thereby conflicting with
the Kirchhoff’s current law (KCL) and failing such a circuit. The high voltage conversion ratios are achieved by
coupling inductors [5], but the voltage spikes due to the accompanying leakage inductances and the complexity in the
corresponding circuit analysis are unavoidable. The voltage-lift technique is used to boost the output voltage, but the
voltage conversion ratios are not high. The voltage conversion ratios can be upgraded by increasing the number of
voltage-boosting cells, additional components or floating active switches are required. This would make the overall
circuits complicated and would require the corresponding isolated drivers.
For the reasons stated above, two high voltage-boosting circuits, based on two bootstrap capacitors and two
inductors, are used. Above all, although two inductors are connected in series during the demagnetizing period,
variations in values of these inductors allow such converters to work appropriately. In addition, based on different
switch turn-on types and different diode connections, two voltage-boosting converters with different voltage
conversion ratios are generated under similar circuit structure. Under the same condition that two inductors and two
capacitors are used except the input capacitor, any one of the proposed voltage conversion ratios is higher than all the
other voltage conversion ratios in the KY boost converter, in the self- circuit and re-lift circuit, and in the positive
output self-lift Luo converter, positive output super lift converter and positive output re-lift Luo converter. In addition,
for each converter, only one half-bridge gate driver and one low side gate driver are needed, but no isolated gate
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Volume No.: II, Special Issue on IEEE Sponsored International Conference on Intelligent Systems and Control (ISCO’15)
driver would be needed. In this paper, the principle operation of these two converters is given along with some
experimental results provided to demonstrate the effectiveness of such converters.
2. Proposed Converter Topology
The proposed two high voltage-boosting converters have individual voltage conversion ratios and individual
pulse-width modulation (PWM) control strategies. It is noted that the difference in circuit between figure 1(a) and (b)
is the location of the anode of D1.Each converter contains three MOSFET switches S1, S2, and S3, two bootstrap
capacitors Cb and Ce, three bootstrap diodes Db, D1, and D2, one output resistor RL. In addition, the input voltage is
signified by Vi, the output voltage is represented by Vo.
It is noted that the proposed converters are based on the charge pump of the KY converter and the series boost
converter.
(a)
(b)
Fig. 1.
Proposed voltage-boosting converters: (a) type 1; (b) type 2.
By doing so, the conversion ratios can be upgraded further. Above all, if the anode of the diode D 1 is
connected to the cathode of the diode Db, the conversion voltage ratio in continuous conduction mode (CCM) is
(3+D)/(1-D),where D is the duty cycle of the PWM control signal created from the controller, whereas if the anode of
the diode Db with switch turn-on types different from those of the former, the conversion ratio in CCM is (3-D)/(1D).Therefore, the proposed converters can be used according to industrial applications.
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3. Basic Operating Principles
There are some assumptions are given as follows: a) the blanking times between the switches are omitted b)
during the turn-on period the voltage drop across the switches and diodes are negligible and c) since the bootstrap
capacitor Cb and Ce, operating based on the charge pump principle, are abruptly charged to some voltage within a
very short time, which is much less than the switching period Ts, the values of Cb and Ce are large enough to keep the
voltages across themselves constant at some values, and hence it is reasonable that the voltages across the capacitors
Cb and Ce are Vi and 2Vi for type 1,respectively,and the voltages across the capacitors Cb and Ce are both Vi for type
2. For these two converters to be considered, the PWM turn-on types for three switches and the voltages on the bootstrap capacitors are tabulated
in Table I.
Table 1
PWM Turn-on Types for Switches and Voltages on Bootstrap Capacitors
Above all converters operated in the continous conduction mode (CCM) and in the discontinuous conduction mode
(DCM).
3.1. Type 1(Proposed voltage-boosting converter)
3.1.1. CCM(Continous Conduction Mode)operation:
a) Mode 1: In this mode switches S1 and S3 are turned on the capacitor Ce is immediately charged and the
inductors are magnetized as the diode Do is reverse biased due to turning on the S3 switch, during this period the
output voltage capacitor will supply the power to the load.
b) Mode 2: In this mode switch S2 is turned on the capacitor Cb is immediately charged to input voltage.
The capacitor Ce is going to be discharged and the inductors are demagnetized. The total voltage will be
appeared across the load.
Fig. 2.
Power flow of type 1 operated in mode 1 with CCM.
The voltage conversion ratio in the continous conduction mode is given by
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3.1.1. DCM(Discontinous Conduction Mode)operation:
a) Mode 1: In this mode the operating principle is same as that for type 1 operated in CCM in mode 1.
b) Mode 2: In this mode, the operating principle is same as that for type 1 operated in CCM in mode 2.
Fig. 3.
Power flow of type 1 operated in mode 2 with CCM.
Fig. 4.
Power flow of type 1 operated in mode 3 with DCM.
c) Mode 3: In this mode, all the switches and diodes are turned off and the currents in two inductors are
zero. Hence, the energy needed by the load is supplied from Co.
3.2.Type 2(Proposed voltage-boosting converter
3.2.1. CCM(Continous Conduction Mode)operation:
a) Mode 1: In this mode switches S2 and S3 are turned on the capacitors and will be charged to input
voltage and the inductors and will be magnetized as the switch is turned on the diode is reverse biased, during
this period the output capacitor will deliver the power to the load.
b) Mode 2: In this mode, the switch S1 is turned on and remaining switches will be in off condition. Here,
both the capacitors will be discharged and the inductors L1 and L2 will be demagnetized and the output capacitor
will be charged. Hence, the output voltage will be boosted and is higher than the input voltage .
3.2.2. DCM(Discontinous Conduction Mode)operation:
a) In this mode, the operating principle is same as that for type 2 operated in CCM in mode 1.
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b) Mode 2: In this mode, the operating principle is same as that for type 2 operated in CCM in mode 2.
Fig. 5.
Power flow of type 2 operated in mode 1 with CCM.
Fig. 6.
Power flow of type 2 operated in mode 2 with CCM.
Fig. 7.
Power flow of type 2 operated in mode 3 with DCM.
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c) Mode 3: In this mode, all the switches and diodes are turned off, and the currents in two inductors are
zero. Hence the energy needed by the load is supplied from Co.
Fig. 8.
Proposed overall system block diagram for type 1
4. Simulation Results
MATLAB/SIMULINK is used for the simulation results. It is a high performance language for technical
computing. It integrates computation, visualization, and programming in an easy to use environment where problems
and solutions are expressed in familiar mathematical notation.
Figure 9 shows the simulation diagram of type 1 converter circuit. By observing the figure 11 the capacitor
voltage Cb and Ce are approximately equal to Vi and 2Vi respectively for type 1circuit.In figure 15 the capacitor
voltage Cb and Ce are equal to Vi for type 2 circuit. Figure 12 shows the output voltage for type 2 circuit
Fig. 9.
Simulation diagram for type 1 converter
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250
200
Vout(v)
150
100
50
0
0
1
Fig. 10.
2
3
4
5
Time(s)
6
7
8
9
10
Simulation waveform for the output voltage of type 1 converter
30
25
Vc1(v)
20
15
10
5
0
-5
0
1
2
3
4
5
Time(s)
6
7
8
9
10
(a)
100
90
80
Vc2(v)
70
60
50
40
30
20
10
0
1
2
3
4
5
time(s)
6
7
8
9
10
(b)
Fig. 11.
(a) & (b) Simulation waveform for capacitor voltages Cb and Ce
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Fig. 12.
Simulation diagram for type 2 converter
Vo (v)
250
200
150
100
50
0
Fig. 13.
0
1
2
3
4
5
6
7
8
Time(s)
9
10
Simulation waveform for the output voltage of type 2 converter
VCb (v)
40
35
30
25
20
15
10
5
0
-5
0
1
2
3
4
5
6
7
8
9
Time(s)
(a)
200
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VCe (v)
45
40
35
30
25
20
15
10
5
0
1
2
3
4
5
6
7
8
9
10
Time(s)
Fig. 14.
a) & (b)Simulation waveform for capacitor voltages Cb and Ce
From the simulation results, the both converters exhibit good performances and different voltage conversion ratios
obtained. The output voltage of type 2 converter is higher than that of type 1 converter.
5. Conclusion
The high voltage-boosting converters are used, which is based on inductors connected in series with
bootstrap capacitors. There are two types of high voltage-boosting converters, depending on the circuit connection
and the PWM control strategy. By changing the connection position of the anode of the diode and by using different
pulse-width modulation control strategies, different voltage conversion ratios can be obtained. In addition, for each
converter, the power switches are easy to drive via one half-bridge gate driver and one low-side gate driver. From the
simulation results, such converters exhibit good performances even with different inductances, and hence are suitable
for industrial applications. Other converters have complicated circuit and their conversion ratios are too low. In future
the simulation results will be verified by using hardware.
References
[1] W. Li and X. He, “Review of non-isolated high step-up dc/dc converters in photovoltaic grid-connected
applications,” IEEE Trans.
Ind. Electron, vol. 58, no. 4, pp. 1239-1250, Apr. 2011.
fuel cell as the primary
source,” IEEE Trans. Ind... Electron, vol. 55, no.8, pp.3012-3021, Aug. 2008.
B. Axelrod, Y. Berkovich, and A. Ioinovici, “Switched –capacitor/ switched-inductor structurs for getting
transformerless hybrid dc-dc PWM converters,” IEEE Trans. Circuits Syst. I, Reg. Papers, vol. 55, no. 2,
pp.687-696, Mar, 2008.
K.I. Hwu and Y. T. Yau, “Voltage-boosting converter based on charge pump and coupling inductor with
passive voltage clamping,” IEEE Trans. Ind. Electron, vol. 57, no. 5, pp. 1719-1727, May 2010.
K.C.Tseng and T. J. Liang, “Novel high-efficiency step-up converters” Proc. Inst. Elect. Eng.-Elect. Power
Appl., vol. 151, no. 2, pp. 182-190, Mar. 2004.
W. Li and X. He, “A family of isolated interleaved boost and buck converters with winding-cross-coupled
inductors,” IEEE Trans. Power Electron, vol. 23, no. 6, pp. 3164-3173, Nov. 2008.
L.S. Yang, T. J. Liang, and J. F. Chen, “Transformerless dc-dc converters with high step-up voltage gain,”
IEEE Trans. Ind. Electron, vol. 56, no. 8,pp. 3144-3152,Aug.2009.
[2] H. Tao, J. L. Duarte, and M. A. M. Hendrix, “Line-interactive UPS using a
[3]
[4]
[5]
[6]
[7]
201
ISSN: 2393-994X
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Volume No.: II, Special Issue on IEEE Sponsored International Conference on Intelligent Systems and Control (ISCO’15)
[8] Y. Park, S. Choi, W. Choi, and K. B. Lee, “Soft-switched interleaved boost converters for high step-up and
high power applications,” IEEE Trans. Power Electron, vol. 26, no.10, pp. 2906-2914, Oct. 2011.
[9] K. I. Hwu and Y. T. Yau, “Performance enhancement of boost converter based on PID controller plus
linear-to-nonlinear translator,” IEEE Trans. Power Electron, vol. 25, no 5.5, pp. 1351-1361, May 2010.
[10] K. I. Hwu and Y. T. Yau, “Improvement of one-comparator counter-based PWM control by applying a saw
toothed wave injection method,” in Proc. IEEE.APEC, 2007, vol. l, pp. 478-481.
[11] C.E. Silva, R.P. Bascope, and D.S. Oliveira, “Proposal of a new high voltage-boosting converter for UPS
application,” in Proc.IEEE ISIE, 2006, pp. 1288-1292
[12] R. Gules, L. L. Pfitscher, and L. C. Franco, “An interleaved boost dc-dc converter with large conversion
ratio,” in Proc.IEEE ISIE, 2003, pp.411-416.
[13] K.I. Hwu and Y.T. Yau, “High step-up converter based on charge pump and boost converter,” in
Proc.IEEEIPEC, 2010, pp. 1038-1041.
[14] M. Cacciato, A. Consoli, and V. Crisafulli, “A high voltage gain dc/dc converter for energy harvesting in
single module photovoltaic applications,” in Proc. IEEE ISIE, 2010, pp. 550-555.
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