A New Interleaved Three-Phase Single-Stage PFC AC-DC Converter with Flying Capacitor

ABSTRACT:

A new interleaved three-phase PFC AC-DC single-stage multilevel is proposed in this paper. The proposed converter can operate with reduced input current ripple and peak switch currents due to its interleaved structure, a continuous output inductor current due to its three-level structure, and improved light-load efficiency as some of its switches can be turned on softly. In the paper, the operation of the converter is explained, the steady-state characteristics of the new converter are determined and its design is discussed. The feasibility of the new converter is confirmed with experimental results obtained from a prototype converter and its efficiency is compared to that of another multilevel converter of similar type.

KEYWORDS:

1.      AC-DC power factor correction

2.      Single-stage converters

3.      Three-Phase Systems

4.      Three level converters

5.      Phase shifted modulation.

SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

Fig. 1. An interleaved three-phase three-level converter.

Fig. 2. Proposed single-stage three-level ac-dc converter.

 EXPECTED SIMULATION RESULTS:

(a) Input current and voltage (V: 100 V/div, I: 4 A/div)

(b) Primary voltage of the main transformer (V:100V/div.,t: 4 µs/div.)

(c) V_ds and I_d current of S₄ (V: 100V/div., I:5A/div, t:10 µs/div.s)

Fig. 3. Typical converter waveforms.

Fig. 4. Efficiency of PWM and PSM three-level single-stage ac-dc converters

CONCLUSION:

A new interleaved three-phase, three-level, single-stage power-factor-corrected AC-DC converter using standard phase-shift PWM was presented in this paper. In this paper, the operation of the converter was explained and its feasibility was confirmed with experimental results obtained from a prototype converter. The efficiency of the new converter was compared to that of another converter of the same type. It was shown that the proposed converter has a better efficiency, especially under light-load conditions, and it was explained that this is because energy from the output inductor can always be used to ensure that the very top and the very bottom switches can be turned ON with ZVS, due to a discharge path that is introduced by its flying capacitor.

REFERENCES:

 [1] “Limits for Harmonic Current Emission (Equipment Input Current>16A per Phase),” IEC1000-3-2 International Standard, 1995.

[2] J.M. Kwon, W.Y. Choi, B.H. Kwon, “Single-stage quasi-resonant flyback converter for a cost-effective PDP sustain power module,” IEEE Trans. on Industrial. Elec., vol. 58, no. 6, pp 2372-2377, 2011.

[3] H.S. Ribeiro and B.V. Borges, “New optimized full-bridge single-stage ac/dc converters,” IEEE Trans. on Industrial. Elec., vol. 58, no. 6, pp. 2397-2409, 2011.

[4] N. Golbon, and G. Moschopoulos, “A low-power ac-dc single-stage converter with reduced dc bus voltage variation”, IEEE Trans. on Power Electron., vol. 27, no.8, pp. 3714–3724, Jan. 2012.

[5] H. M. Suraywanshi, M.R. Ramteke. K. L. Thakre, and V. B. Borghate, “Unity-power-factor operation of three phase ac-dc soft switched converter based on boost active clamp topology in modular approach,” IEEE Trans. on Power Elec., vol. 23, no. 1., pp. 229-236, Jan. 2008.

Analysis of Active Islanding Methods for Single phase Inverters

 ABSTRACT:

This paper presents the analysis and comparison of the main active techniques for islanding detection used in grid-connected single phase inverters. These techniques can be divided into two classes: techniques introducing positive feedback in the control of the inverter and techniques based on harmonic injection by the inverter. The algorithms mentioned in this work are simulated in PSIMTM in order to make a comparative analysis and to establish their advantages and disadvantages according to IEEE standards.

KEYWORDS:

1.      Single phase inverter

2.      Active Islanding Detection Methods

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

 Fig.1. Block diagram of the developed inverter

 EXPECTED SIMULATION RESULTS:

Fig. 2. (a) Active power injection. PCC voltage, RMS Voltage and islanding detection. (b) Reactive power injection. PCC voltage, frequency and islanding detection.

Fig. 3. GEFS. PCC voltage, frequency and islanding detection.

Fig. 4. Impedance detection. PCC voltage and islanding detection.

CONCLUSION:

In this paper was presented an analysis of various active methods resident in the inverter for islanding detection in single phase inverters. It became evident that for the same test conditions as established by the IEEE 929 all methods met, however the positive feedback based methods have a longer trip time that those based on harmonic injection because positive feedback methods should reach the threshold of UOV or UOF, whereas methods based on harmonic injection what is sought is to detect variations in the impedance of the grid, which allows to work with smaller detection thresholds. On the other hand, despite these methods are based on disturbing the system and degrading the power quality, their effect is not significant and they are within the harmonic distortion limits set by standards.

REFERENCES:

[1] M, Pietzsch, “Convertidores CC/CA para la conexión directa a red de sistemas fotovoltaicos: comparación entre topologías de 2 y 3 niveles,” Bachelor thesis, Universidad Politécnica de Cataluña, España, Dec. 2004.

[2] V. Task, "Evaluation of islanding detection methods for photovoltaic utility-interactive power systems," Tech. Rep. IEAPVPS T5-09:2002, March. 2002.

[3] P. Mahat, C. Zhe and B. Bak-Jensen, “Review of islanding detection methods for distributed generation,” in Third International Conference on Electric Utility Deregulation and Restructuring and Power Technologies, 2008, pp.2743-2748.

[4] Mohan, N., Underland, T.M.& Robbins, W.P. 2003 Power electronics: converters, applications, and design. 3th ed. International. John Wiley & Sons.

[5] T. Esram and P.L. Chapman, “Comparison of Photovoltaic Array Maximum Power Point Tracking Techniques,” Energy Conversion, IEEE Transactions on , vol.22, no.2, pp.439-449, June 2007.

Analysis and Mathematical Modelling Of Space Vector Modulated Direct Controlled Matrix Converter

ABSTRACT:

Matrix converters as induction motor drivers have received considerable attention in recent years because of its good alternative to voltage source inverter pulse width modulation (VSI-PWM) converters. This paper presents the work carried out in developing a mathematical model for a space vector modulated (SVM) direct controlled matrix converter. The mathematical expressions relating the input and output of the three phase matrix converter are implemented by using MATLAB/SIMULINK. The duty cycles of the switches are modeled using space vector modulation for 0.5 and 0.866 voltage transfer ratios. Simulations of the matrix converter loaded by passive RL load and active induction motor are performed. A unique feature of the proposed model is that it requires very less computation time and less memory compared to the power circuit realized by using actual switches. In addition, it offers better spectral performances, full control of the input power factor, fully utilization of input voltages, improve modulation performance and output voltage close to sinusoidal.

KEYWORDS:

1.      Matrix Converter

2.      Space Vector Modulation

3.      Simulation Model

4.       Induction Motor

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1: Block diagram of simulation model for direct matrix converter

EXPECTED SIMULATION RESULTS:

Figure 2: Result for sector identification

Figure 3: Input and output voltage with passive load for q=0.5; R=135.95Ω, L=168.15mH, V_im=100 V, f_o = 60Hz, f_s = 2kHz

Figure 4: Input and output voltage with passive load for q=0.866; R=135.95Ω, L=168.15mH, V_im=100 V, f_o = 60Hz, f_s = 2kHz

Figure 5: Input and output voltage with loaded induction motor for q=0.5; 3hp, R_s =0.277Ω, R_r=0.183Ω, N_r=1766.9rpm, L_m=0.0538H, L_r=0.05606H, L_s=0.0533H,

f_o=60Hz, f_s=2kHz

Figure 6: Input and output voltage with loaded induction motor for q=0.866; 3hp, R_s =0.277Ω, R_r=0.183Ω, N_r=1766.9rpm, L_m=0.0538H, L_r=0.05606H, L_s=0.0533H, f_o=60Hz, f_s=2kHz

Figure 7: Input current with passive load; R=135.95Ω, L=168.15mH, V_im=100 V, f_o = 60Hz, f_s = 2kHz (a) q=0.5, (b) q = 0.866

                 

Figure 8: Input current with loaded induction motor for q=0.866; 3hp, R_s =0.277Ω, R_r=0.183Ω, N_r=1766.9rpm, L_m=0.0538H, L_r=0.05606H, L_s=0.0533H, f_o=60Hz, f_s=2kHz

CONCLUSION:

The main constraint in the theoretical study of matrix converter control is the computation time it takes for the simulation. This constraint has been overcome by the mathematical model that resembles the operation of power conversion stage of matrix converter. This makes the future research on matrix converter easy and prosperous. The operation of direct control matrix converter was analysed using mathematical model with induction motor load for 0.866 voltage transfer ratio.

 REFERENCES:

[1]. A. Alesina, M.G.B.V., Analysis And Design Of Optimum-Amplitude Nine – Switch Direct AC-AC Converters. IEEE Trans. On Power. Electronic, 1989. 4.

[2]. D. Casadei, G.S., A. Tani, L. Zari, Matrix Converters Modulation Strategies : A New General Approach Based On Space-Vector Representation Of The Switch State. IEEE Trans. On Industrial Electronic, 2002. 49(2).

[3]. P. W. Wheeler, J.R., J. C. Claire, L. Empringham, A. Weinstein, Matrix Converters : A Technology Review. IEEE Trans. On Industrial Electronic, 2002. 49(2).

[4]. H. Hara, E.Y., M. Zenke, J.K. Kang, T. Kume. An Improvement Of Output Voltage Control Performance For Low Voltage Region Of Matrix Converter. In Proc 2004 Japan Industry Applications Society Conference, No. 1-48, 2004. (In Japanese). 2004

[5]. Ito J, S.I., Ohgushi H, Sato K, Odaka A, Eguchi N., A Control Method For Matrix Converter Based On Virtual Ac/Dc/Ac Conversion Using Carrier Comparison Method. Trans Iee Japan Ia 2004. 124-D: P. 457–463.

Analysis and Design of High-Frequency Isolated Dual-Bridge Series Resonant DC/DC Converter

 ABSTRACT:

Bidirectional dual-bridge dc/dc converter with high frequency isolation is gaining more attentions in renewable energy system due to small size and high-power density. In this paper, a dual-bridge series resonant dc/dc converter is analyzed with two simple modified ac equivalent circuit analysis methods for both voltage source load and resistive load. In both methods, only fundamental components of voltages and currents are considered. All the switches may work in either zero-voltage-switching or zero-current-switching for a wide variation of voltage gain, which is important in renewable energy generation. It is also shown in the second method that the load side circuit could be represented with an equivalent impedance. The polarity of cosine value of this equivalent impedance angle reveals the power flow direction. The analysis is verified with computer simulation results. Experimental data based on a 200 W prototype circuit is included for validation purpose.

KEYWORDS:

1.      Analysis and simulation

2.      Dc-to-dc converters

3.      Modeling

4.      Renewable energy systems

5.       Resonant converters

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1. Hybrid renewable energy generation system with battery back-up function.

 EXPECTED SIMULATION RESULTS:

Fig. 2. Output power versus phase-shift angle φ. (a) F = 1.1, M = 0.95,

and different Q. (b) F = 1.1, Q = 1, and different converter gain M.

Fig. 3. Operation in charging mode (V_i = 110 V, V_o = 100 V), simulated waveforms of v_AB and v_CD , resonant current i_S , resonant capacitor voltage v_Cs , output current before filter capacitor i_o for output power (a) P_o = 200W, (b) P_o = 100 W, and (c) P_o = 20 W.

Fig. 4. Operation in regeneration mode (V_i = 110V, V_o = 100 V). Simulated waveforms of v_AB and v_CD , resonant current i_S , resonant capacitor voltage vC_s , output current before filter capacitor i_o for output power P_o = −200 W.

Fig. 5. Full-load test results (V_i = 110 V, V_o = 100 V). (a) From top to bottom v_AB (100V/div), v_CD (100V/div), is (2A/div). (b) v_C (100V/div). (c) Primary switch current (1A/div). (d) Secondary switch current

(1A/div).

Fig. 6. (a) Half-load test results (Vi = 110 V, Vo = 100 V): from top to bottom: vAB (100 V/div), vCD (100 V/div), is (2 A/div), primary switch current (1 A/div), secondary switch current (1 A/div). (b) 10% load condition test results (Vi = 110 V, Vo = 100 V): from top to bottom: waveforms of (a) repeated.

Fig. 7. Output current of secondary converter under different load levels (Vi = 110 V, Vo = 100 V). (a) 200 W (2A/div). (b) 100 W (2A/div). (c) 20 W (1A/div).

 CONCLUSION:

In this paper, a HF isolated dual-bridge series resonant dc/dc converter has been proposed, which is suitable for renewable energy generation applications. Two modified ac equivalent circuit analysis methods were presented to analyze the DBSRC. First method used was voltage-source type of load, whereas, second method uses a controlled rectifier with resistive load. It was shown that an equivalent impedance could be used to represent the secondary part circuit in the case of resistive load to include the bidirectional feature. Detailed analysis has been presented for both the methods. Same results were obtained from both the methods. ZVS turn-ON for primary-side switches and ZCS turn-OFF for secondary-side switches could be achieved for all load and input/output voltage conditions. Design procedure has been illustrated by a 200Wdesign example. Through the SPICE simulation and experimental results, the theoretical results have been verified.

In the DAB converter, performance of the converter is heavily dependent on the leakage inductance of the transformer (used for power transfer and should be as small as possible) [15], [19], whereas, in the DBSRC, leakage inductance is used as part of resonant tank. If the DAB converter is used for application with wide input/output voltage variation, ZVS of primary-side converter may be hard to achieve [19]. DBSRC has low possibility of transformer saturation due to the series capacitor (that can be split as mentioned earlier). The disadvantage of DBSRC is the size of resonant tank (additional capacitor), which brings extra size and cost. Further work is required to compare the DAB converter with the DBSRC for such applications. In the future, more study will be done based on the DBSRC. Efforts will focus on modifications to realize ZVS on the secondary side to reduce the switching losses further. With all two quadrant switches replaced with four-quadrant switches [23], the converter could be controlled as an ac/ac electronic transformer, which can be used in doubly fed induction generator (DFIG) based wind generation system. For high-power applications, multicells of the converter may be used to meet high power density requirements.

REFERENCES:

[1] L. H. Hansen, L. Helle, F. Blaabjerg, E. Ritchie, S. Munk-Nielsen, H. Bindner, P. Sørensen, and B. Bak-Jenseen, “Conceptual survey of generators and power electronics for wind turbines,” Risø Nat. Lab., Roskilde, Denmark, Tech. Rep. Risø-R-1205(EN), ISBN 87-550-2743-8, Dec. 2001.

[2] N. Kasa, Y. Harada, T. Ida, and A. K. S. Bhat, “Zero-current transitions converters for independent small scale power network system using lower power wind turbines,” in Proc. IEEE Int. Symp. Power Electron., Electric Drives, Autom. Motion 2006, May 23–26, pp. 1206–1210.

[3] J. Lai and D. J. Nelson, “Energy management power converters in hybrid electric and fuel cell vehicles,” Proc. IEEE, vol. 95, no. 4, pp. 766–777, Apr. 2007.

[4] H. Tao, A. Kotsopoulos, J. L. Duarte, andM. A.M. Hendrix, “Multi-input bidirectional dc-dc converter combining dc-link and magnetic-coupling for fuel cell systems,” in Proc. 40th IEEE IAS Annu. Meet., Oct. 2005, vol. 3, pp. 2021–2028.

[5] F. Z. Peng, H. Li, G.-J. Su, and J. S. Lawler, “A new ZVS bidirectional dc–dc converter for fuel cell and battery application,” IEEE Trans. Power Electron., vol. 19, no. 1, pp. 54–65, Jan. 2004.