A High Step-Up DC to DC Converter Under Alternating Phase Shift Control for Fuel Cell Power System

ABSTRACT

This paper investigates a novel pulse width modulation (PWM) scheme for two-phase interleaved boost converter with voltage multiplier for fuel cell power system by combining alternating phase shift (APS) control and traditional interleaving PWM control. The APS control is used to reduce the voltage stress on switches in light load while the traditional interleaving control is used to keep better performance in heavy load. The boundary condition for swapping between APS and traditional interleaving PWM control is derived. Based on the aforementioned analysis, a full power range control combining APS and traditional interleaving control is proposed. Loss breakdown analysis is also given to explore the efficiency of the converter. Finally, it is verified by experimental results.

 KEYWORDS: Boost converter, Fuel cell, Interleaved, Loss breakdown, Voltage multiplier.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

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Fig. 1. Grid-connected power system based on fuel cell.

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Fig. 2. Main theoretical waveforms at boundary condition.

EXPERIMENTAL RESULTS:

 image003image004 image005 image006Fig.3 Experimental results at boundary condition with traditional interleaving control (L = 1158 μH, R = 2023 Ω, and D = 0.448). (a) CH1-S1 Driver Voltage, CH2 L1 Current, CH3-S1 Voltage Stress, CH4-Output Voltage, (b) CH1-S1 Driver Voltage, CH2 C1 Current, CH3-S1 Voltage Stress, CH4-OutputVoltage, (c) CH1-S1 DriverVoltage,CH2 D1 Current,CH3-S1 Voltage Stress, CH4-Output Voltage, (d) CH1-S1 Driver Voltage, CH2 DM1 Current, CH3-S1 Voltage Stress, CH4-Output Voltage.

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Fig. 4. Traditional interleaving control at nominal load (L = 1158 μH and R = 478 Ω).]

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Fig. 5. Traditional interleaving control in Zone A (L = 1158 μH and R = 1658 Ω).

CONCLUSION

The boundary condition is derived after stage analysis in this paper. The boundary condition classifies the operating states into two zones, i.e., Zone A and Zone B. The traditional interleaving control is used in Zone A while APS control is used in Zone B. And the swapping function is achieved by a logic unit. With the proposed control scheme, the converter can achieve low voltage stress on switches in all power range of the load, which is verified by experimental results.

 REFERENCES

[1] N. Sammes, Fuel Cell Technology: Reaching Towards Commercialization. London, U.K.: Springer-Verlag, 2006.

[2] G. Fontes, C. Turpin, S. Astier, and T. A. Meynard, “Interactions between fuel cells and power converters: Influence of current harmonics on a fuel cell stack,” IEEE Trans. Power Electron., vol. 22, no. 2, pp. 670–678, Mar. 2007.

[3] P. Thounthong, B. Davat, S. Rael, and P. Sethakul, “Fuel starvation,” IEEE Ind. Appl. Mag., vol. 15, no. 4, pp. 52–59, Jul./Aug. 2009.

[4] S.Wang,Y.Kenarangui, and B. Fahimi, “Impact of boost converter switching frequency on optimal operation of fuel cell systems,” in Proc. IEEE Vehicle Power Propulsion Conf., 2006, pp. 1–5.

[5] S. K. Mazumder, R. K. Burra, and K. Acharya, “A ripple-mitigating and energy-efficient fuel cell power-conditioning system,” IEEE Trans. Power Electron., vol. 22, no. 4, pp. 1437–1452, Jul. 2007.

A High Step-Up Converter with Voltage-Multiplier Modules for Sustainable Energy Applications

ABSTRACT

This paper proposes a novel isolated high step-up converter for sustainable energy applications. Through an adjustable voltage-multiplier module, the proposed converter achieves a high step-up gain without utilizing either a large duty ratio or a high turns ratio. The voltage-multiplier modules are composed of coupled inductors and switched capacitors. Due to the passive lossless clamped performance, leakage energy is recycled, which alleviates a large voltage spike across the main switches and improves efficiency. Thus, power switches with low levels of voltage stress can be adopted for reducing conduction losses. In addition, the isolated topology of the proposed converter satisfies electrical-isolation and safety regulations. The proposed converter also possesses continuous and smooth input current, which decreases the conduction losses, lengthens life time of the input source, and constrains conducted electromagnetic-interference problems. Finally, a prototype circuit with 40 V input voltage, 380 V output, and 500 W maximum output power is operated to verify its performance. The maximum efficiency is 94.71 % at 200 W, and the full-load efficiency is 90.67 % at 500 W.

 KEYWORDS

  1. High Step-Up
  2. Voltage-Multiplier Module
  3. Isolated Converter

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

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Fig. 1. Block diagram of a typically sustainable energy system.

CIRCUIT DIAGRAM:

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Fig. 2. Proposed isolated high step-up converter for sustainable e
nergy applications.

EXPERIMENTAL RESULTS:

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(a) Measured waveforms of vDS1, vDS2, iLin and iLk

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(b) Measured waveforms of vDc, vDr and iDr

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(C)Measured waveforms of vDf1, vDf2, iDf1 and iDf2

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(d) Measured waveforms of vDo, iDo and Vo

Fig.3 The experimental waveforms measured at a full load of 500 W.

CONCLUSION

This paper has presented the theoretical analysis of steady-state and experimental results for the proposed converter, which successfully demonstrates its performance. A prototype isolated converter has been successfully implemented with a high step-up ratio and high efficiency for sustainable energy applications. The presented circuit topology inherently makes the input current continuous and smooth, which decreases the conduction losses, lengthens the life time of the input source, and constrains conducted EMI problems. In addition, the lossless passive clamp function recycles the leakage energy and constrains/lowers the voltage spikes across the power switches. Meanwhile, the voltage stress on the power switch is restricted and is much lower than the output voltage Vo, which is 380 V. Furthermore, the full-load efficiency is 90.67% at Po =500 W, and the maximum efficiency is 94.71% at Po = 200 W. Thus, the proposed converter is suitable for renewable-energy applications that need high step-up conversion and have electrical-isolation requirements.

 REFERENCES

  1. Kefalas, and A. Kladas, “Analysis of transformers working under heavily saturated conditions in grid-connected renewable energy systems,” IEEE Trans. Ind. Electron., vol. 59, no. 5, pp. 2342–2350, May 2012

2. Jonghoon Kim, Jaemoon Lee, and B. H. Cho, “Equivalent circuit modeling of pem fuel cell degradation combined with a lfRC,” IEEE Trans. Ind. Electron., vol. 60, no. 11, pp. 5086–5094, Nov. 2013.

3. Prasanna U R, and Akshay K. Rathore, “Extended range zvs active-clamped current-fed full-bridge isolated dc/dc converter for fuel cell applications: analysis, design, and experimental results,” IEEE Trans. Ind. Electron., vol. 60, no. 7, pp. 2661–2672, July 2013.

4. Shih-Jen Cheng, Yu-Kang Lo, Huang-Jen Chiu, and Shu-Wei Kuo, “High-efficiency digital-controlled interleaved power converter for high-power pem fuel-cell applications,” IEEE Trans. Ind. Electron., vol. 60, no. 2, pp. 773–780, Feb. 2013.

5. Changzheng Zhang, Shaowu Du, and Qiaofu Chen, “A novel scheme suitable for high-voltage and large-capacity photovoltaic power stations,” IEEE Trans. Ind. Electron., vol. 60, no. 9, pp. 3775–3783, Sept. 2013.

 

A High Gain Input-Parallel Output-Series DC/DC Converter with Dual Coupled Inductors

ABSTRACT

High voltage gain dc–dc converters are required in many industrial applications such as photovoltaic and fuel cell energy systems, high-intensity discharge lamp (HID), dc back-up energy systems, and electric vehicles. This paper presents a novel input-parallel output-series boost converter with dual coupled inductors and a voltage multiplier module. On the one hand, the primary windings of two coupled inductors are connected in parallel to share the input current and reduce the current ripple at the input. On the other hand, the proposed converter inherits the merits of interleaved series-connected output capacitors for high voltage gain, low output voltage ripple, and low switch voltage stress. Moreover, the secondary sides of two coupled inductors are connected in series to a regenerative capacitor by a diode for extending the voltage gain and balancing the primary-parallel currents. In addition, the active switches are turned on at zero current and the reverse recovery problem of diodes is alleviated by reasonable leakage inductances of the coupled inductors. Besides, the energy of leakage inductances can be recycled. A prototype circuit rated 500-W output power is implemented in the laboratory, and the experimental results shows satisfactory agreement with the theoretical analysis.

 KEYWORDS

  1. DC–DC converter
  2. Dual coupled inductors
  3. High gain
  4. Input-parallel output-series.

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

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Fig. 1. Equivalent circuit of the presented converter.

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Fig.2 Key theoretical waveforms.

 EXPERIMENTAL VERIFICATIONS:

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Fig.3 Key experimental current waveforms.

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Fig.4 Voltage stress waveforms of power components.

CONCLUSION

For low input-voltage and high step up power conversion, this paper has successfully developed a high-voltage gain dc–dc converter by input-parallel output-series and inductor techniques. The key theoretical waveforms, steady-state operational principle, and the main circuit performance are discussed to explore the advantages of the proposed converter. Some important characteristics of the proposed converter are as follows: 1) it can achieve a much higher voltage gain and avoid operating at extreme duty cycle and numerous turn ratios; 2) the voltage stresses of the main switches are very low, which are one fourth of the output voltage under N = 1; 3) the input current can be automatically shared by each phase and low ripple currents are obtained at input; 4) the main switches can be turned ON at ZCS so that the main switching losses are reduced; and 5) the current falling rates of the diodes are controlled by the leakage inductance so that the diode reverse-recovery problem is alleviated. At the same time, there is a main disadvantage that the duty cycle of each switch shall be not less than 50% under the interleaved control with 180phase shift.

 REFERENCES

[1] C.Cecati, F. Ciancetta, and P. Siano, “A multilevel inverter for photovoltaic systems with fuzzy logic control,” IEEE Trans. Ind. Electron., vol. 57, no. 12, pp. 4115–4125, Dec. 2010.

[2] X. H. Yu, C. Cecati, T. Dillon, and M. G. Simoes, “The new frontier of smart grid,” IEEE Trans. Ind. Electron. Mag., vol. 15, no. 3, pp. 49–63, Sep. 2011.

[3] G. Fontes, C. Turpin, S. Astier, and T. A. Meynard, “Interactions between fuel cell and power converters: Influence of current harmonics on a fuel cell stack,” IEEE Trans. Power Electron., vol. 22, no. 2, pp. 670–678, Mar. 2007.

[4] J. Y. Lee and S. N. Hwang, “Non-isolated high-gain boost converter using voltage-stacking cell,” Electron. Lett., vol. 44, no. 10, pp. 644–645, May 2008.

[5] Z. Amjadi and S. S. Williamson, “Power-electronics-based solutions for plug-in hybrid electric vehicle energy storage and management systems,” IEEE Trans. Ind. Electron., vol. 57, no. 2, pp. 608–616, Feb. 2010.