PV BALANCERS: CONCEPT, ARCHITECTURES, AND REALIZATION

ABSTRACT:

This paper presents a new concept of module integrated converters called PV balancers for photovoltaic applications. The proposed concept enables independent maximum power point tracking (MPPT) for each module, and dramatically decreases the requirements for power converters. The power rating of a PV balancer is less than 20% of its counterparts, and the manufacturing cost is thus significantly reduced. In this paper, two architectures of PV balancers are proposed, analyzed, realized, and verified through simulation and experimental results. It is anticipated that the proposed approach will be a low-cost solution for future photovoltaic power systems.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

(a) Architecture I of PV balancers

(b) Architecture II of PV balancers

Figure 1. Two possible architectures of PV balancers

EXPECTED SIMULATION RESULTS:

Figure 2. Output voltages of PV balancers in Architecture I

Figure 3. Output voltages of PV balancers in Architecture II

CONCLUSION:

A new concept of module-integrated converters called PV balancers has been proposed and verified in this paper. The proposed concept enables independent maximum power point tracking (MPPT) for each module, and dramatically decreases the requirements for power converters. PV balancers may have a significant economic value for photovoltaic systems in the future. Future work will be focused on power converter optimization, dc bus voltage control, and developing a highly efficient inverter for PV balancers.

 REFERENCES:

[1]         S. Kjaer, J. Pedersen and F. Blaabjerg, “A review of single-phase grid-connected inverters for photovoltaic modules,” IEEE Trans. Ind. App., vol. 41, no. 5, pp. 1292-1306, Sept. 2005.

[2]         L. Linares, R. Erickson, S. MacAlpine, and M. Brandemuehl, “Improved energy capture in series string photovoltaic via smart distributed power electronics,” APEC’09, pp. 904-905, 2009.

[3]         “Power circuit design for solar magic sm3320,” Application Note AN-2124, National Semiconductor, 2011.

[4]         A. Trubitsyn, B. Pierquet, A. Hayman, G. Gamache, C. Sullivan, and D. Perreault, “High-efficiency inverter for photovoltaic applications,” ECCE’10, pp. 2803-2810, Sept. 2010.

[5]         B. Pierquet, and D. Perreault, “A single-phase photovoltaic inverter topology with a series-connected power buffer,” ECCE’10, pp. 2811- 2818, Sept. 2010.

LLC Resonant Inverter for Induction Heating with Asymmetrical Voltage-Cancellation Control

ABSTRACT

This paper proposes a high efficiency LLC resonant inverter for induction heating applications by using asymmetrical voltage cancellation control. The proposed control method is implemented in a full-bridge topology for induction heating application. The operating frequency is automatically adjusted to maintain a small constant lagging phase angle under load parameter variation. The output power is controlled using the asymmetrical voltage cancellation technique. The LLC resonant tank is designed without the use of output transformer. This results in an increase of the net efficiency of the induction heating system. The validity of the proposed method is verified through computer simulation and hardware experiment at the operating frequency of 93 to 96 kHz.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 Fig. 1. Full-bridge series and parallel resonant inverter.

EXPECTED SIMULATION RESULTS

Fig. 2. Voltage and current waveforms at 100 % duty cycle

Fig. 3. Simulation results with α=70^o

CONCLUSION

This work proposes the full-bridge LLC resonant inverter for induction heating application. The phase-locked loop allows resonant frequency tracking under load parameter variation. The analytical expression of the output power as a function of the shifted phase angle is given in this work. Based on the derived expression, the asymmetrical voltage cancellation can be used to control output power to the induction coil. Simulation and experimental studies are performed to verify the proposed control method. The resonant frequency tracking and the adjustment of pulse voltage together ensure the maximum power transfer to the load throughout the heating cycle with minimal loss.

REFERENCES

[1]         M. Kamli, S. Yamamoto, and M. Abe, “A 50-150 kHz Half- Bridge Inverter for induction heating Application,” IEEE Trans. Industrial Electronics, Vol. 43, February 1996. pp. 163-172

[2]         E. J. Davies , J. and Simpson, P., 1979, Induction Heating Handbook. , McGraw-Hill, UK ,

[3]         Chudjuarjeen, S., Koompai, C.and Monyakul, “Full-bridge current-fed inverter with automatic frequency control for forging application”, IEEE Tencon 2004, Vol. 4, pp.128-131, Nov. 2004

[4]         Viriya, P.; Sittichok, S.; Matsuse, K.; “Analysis of High-Frequency Induction Cooker with Variable Frequency Power Control,” Power Conversion Conference, 2002 .PCC Osaka 2002 .Proceedings of the Volume 3, 5 -2 April 2002Page(s): 1507 - 1502vol.. 3

[5]         Nam-Ju Park, Dong-Yun Lee, and Dong-Seok Hyun,”A Power-Control Scheme With Constant Switching Frequency in Class-D Inverter for Induction-Heating Jar Application”, IEEE Trans. Industrial Electronics, vol. 54, no. 3, Jun. 2007

Doubly Fed Induction Generator for Wind Energy Conversion Systems with Integrated Active Filter Capabilities

ABSTRACT

This paper deals with the operation of doubly fed induction generator (DFIG) with an integrated active filter capabilities using grid-side converter (GSC). The main contribution of this work lies in the control of GSC for supplying harmonics in addition to its slip power transfer. The rotor-side converter (RSC) is used for attaining maximum power extraction and to supply required reactive power to DFIG. This wind energy conversion system (WECS) works as a static compensator (STATCOM) for supplying harmonics even when the wind turbine is in shutdown condition. Control algorithms of both GSC and RSC are presented in detail. The proposed DFIG-based WECS is simulated using MATLAB/Simulink. A prototype of the proposed DFIGbased WECS is developed using a digital signal processor (DSP). Simulated results are validated with test results of the developed DFIG for different practical conditions, such as variable wind speed and unbalanced/single phase loads.

KEYWORDS

1.      Doubly fed induction generator (DFIG)

2.      Integrated active filter

3.      Nonlinear load

4.      Power quality

5.      Wind energy conversion system (WECS).

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Proposed system configuration.

Fig. 2. Control algorithm of the proposed WECS.

EXPECTED SIMULATION RESULTS

Fig. 3. Simulated performance of the proposed DFIG-based WECS at fixed wind speed of 10.6 m/s (rotor speed of 1750 rpm).

Fig. 4. Simulated waveform and harmonic spectra of (a) grid current (iga), (b) load current (ila), (c) stator current (isa), and (d) grid voltage for phase “a”

(vga) at fixed wind speed of 10.6 m/s (rotor speed of 1750 rpm).

Fig. 5. Simulated performance of the proposed DFIG-basedWECS working as a STATCOM at zero wind speed.

Fig. 6. Simulated waveforms and harmonic spectra of (a) load current (ila) and (b) grid current (iga) working as a STATCOM at wind turbine shut down condition.

Fig. 7. Simulated performance of proposed DFIG for fall in wind speed.

Fig. 8. Dynamic performance of DFIG-based WECS for the sudden removal and application of local loads.

CONCLUSION

The GSC control algorithm of the proposed DFIG has been modified for supplying the harmonics and reactive power of the local loads. In this proposed DFIG, the reactive power for the induction machine has been supplied from the RSC and the load reactive power has been supplied from the GSC. The decoupled control of both active and reactive powers has been achieved by RSC control. The proposed DFIG has also been verified at wind turbine stalling condition for compensating harmonics and reactive power of local loads. This proposed DFIG-based WECS with an integrated active filter has been simulated using MATLAB/Simulink environment, and the simulated results are verified with test results of the developed prototype of this WECS. Steady-state performance of the proposed DFIG has been demonstrated for a wind speed. Dynamic performance of this proposed GSC control algorithm has also been verified for the variation in the wind speeds and for local nonlinear load.

REFERENCES

[1]           D. M. Tagare, Electric Power Generation the Changing Dimensions. Piscataway, NJ, USA: IEEE Press, 2011.

[2]           G. M. Joselin Herbert, S. Iniyan, and D. Amutha, “A review of technical issues on the development of wind farms,” Renew. Sustain. Energy Rev., vol. 32, pp. 619–641, 2014.

[3]           I.Munteanu, A. I. Bratcu, N.-A. Cutululis, and E. Ceang, Optimal Control of Wind Energy Systems Towards a Global Approach. Berlin, Germany: Springer-Verlag, 2008.

[4]           A. A. B. Mohd Zin, H. A. Mahmoud Pesaran, A. B. Khairuddin, L. Jahanshaloo, and O. Shariati, “An overview on doubly fed induction generators controls and contributions to wind based electricity generation,” Renew. Sustain. Energy Rev., vol. 27, pp. 692–708, Nov. 2013.

[5]           S. S. Murthy, B. Singh, P. K. Goel, and S. K. Tiwari, “A comparative study of fixed speed and variable speed wind energy conversion systems feeding the grid,” in Proc. IEEE Conf. Power Electron. Drive Syst. (PEDS’07), Nov. 27–30, 2007, pp. 736–743.

Simulation of a Space Vector PWM Controller for a Three-Level Voltage-Fed Inverter Motor Drive

Simulation of a Space Vector PWM Controller for a Three-Level Voltage-Fed Inverter Motor Drive

ABSTRACT

Multilevel voltage-fed inverters with space vector pulse width modulation strategy are gained importance in high power high performance industrial drive applications. This paper proposes a new simplified space vector PWM method for a three-level inverter fed induction motor drive. The three- level inverter has a large number of switching states compared to a two-level inverter. In the proposed scheme, three-level space vector PWM inverter is easily implemented as conventional two-level space vector PWM inverter. Therefore, the proposed method can also be applied to multilevel inverters. In this work, a three-level inverter using space vector modulation strategy has been modeled and simulated. Simulation results are presented for various operation conditions using R-L load and motor load to verify the system model.

KEYWORDS

1.      Space vector PWM

2.      Three-level inverters

3.      Multilevel inverters

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 Fig.1 Three level multilevel inverter using cascaded inverters with separated DC sources

   

EXPECTED SIMULATION RESULTS

Fig.2 The line output voltage waveform for fo=10Hz and m=0.65

Fig.3 Three-phase line output current waveforms for fo=10Hz and m=0.65

Fig.4 The line output voltage waveform and its spectrum for fo=10Hz and m=0.65.

Fig.5 The line output voltage waveform for fo=50Hz and m=0.7

CONCLUSION

The space vector PWM algorithm for a three level voltage-fed inverter using cascaded H-bridges inverter has been modeled and simulated using Simulink/MATLAB package program. Simulation results have been given for both R-L and induction motor loads using 1 kHz switching frequency with various output frequencies. The proposed control algorithm used in the three-level inverter can be easily applied to multilevel inverters with more than three levels. It has been shown that high quality waveforms at the output of the multilevel inverter can be obtained even with 1 kHz of low switching frequency.

REFERENCES

[1]    P.M. Bhagwat and V.R. Stefanovic, “Generalized Structure of A Multilevel Inverter”, IEEE Trans. On I.A., Vol. IA-19, n.6, 1983, pp. 1057-1069.

[2]      S.K. Mondal, J.O.P Pinto, B.K. Bose, “A Neural- Network-Based Space Vector PWM Controller for a Three-Level Voltage-Fed Inverter Induction Motor Drive”, IEEE Trans. on I.A., Vol. 38, no. 3, May/June 2002, pp.660-669.

[3]       S.K. Mondal, B.K. Bose, V. Oleschuk and J.O.P Pinto, “Space Vector Pulse Width Modulation of Three-Level Inverter Extending Operation Into Overmodulation Region”, IEEE Trans. on Power Electronics, Vol. 18, no. 2, March 2003, pp.604-611.

[4]      M. Manjrekar and G. Venkataramanan, “Advanced Topologies and Modulation Strategies for Multilevel Inverters”, Power Electronics Specialists Conference, Vol. 2, 23-27 June 1996, pp. 1013-1018.

[5]       A. Nabae, I. Takahashi and H. Akagi, “A New Neutral-Point-Clamped PWM Inverter”, IEEE Trans. on I.A., Vol. 17, No.5, September/October 1981, pp.518-523.

Performance Investigation of Space Vector Pulse Width Modulated Inverter fed Induction Motor Drive

 ABSTRACT

This paper introduces Space Vector Pulse Width Modulation (SVPWM) Technique in detail and its implementation in MATLAB. Performance investigation of Sinusoidal Pulse Width Modulated and Space Vector Modulated Voltage Source Inverter (VSI) fed Induction Motor (1M) drive has done and their simulation results are compared with each other. Also FFT analysis for Sinusoidal Pulse Width Modulated and Space Vector Pulse Width Modulated VSl fed 1M drive is done and compared with each other. 20 HP 1M is used. The study confirms that 1M gives improved performance when it is fed from Space Vector Pulse Width Modulated VS1.

KEYWORDS

1.      Space Vector Pulse Width Modulation (SVPWM)

2.      Sinusoidal Pulse Width Modulation (SPWM)

3.      Two Level Voltage Source Inverter (VSI)

4.      Total Harmonic Distortion (THD)

5.      Three Phase Induction Motor (1M).

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 Figure 1. Block diagram of SVPWM

EXPECTED SIMULATION RESULTS

Figure 2. (a) Line to Line Voltage (Vab) of Space Vector Modulated VSI (b) Stator current (i,..) of IM (c) Electromagnetic Torque (Te) of IM (d) Rotor Speed (Nm) of 1M.

Figure 3 (a) Line to Line Voltage (Vab) of Sinusoidal Pulse Width Modulated VSI (b) Stator current (i,a) of IM ( c) Electromagnetic Torque (Te) of IM (d) Rotor Speed (Nm) of IM

Figure 4. FFT Analysis of Line to Line Voltage (Vab) of (a) Sinusoidal Pulse Width Modulated VSL (b) Space Vector Modulated VSL

CONCLUSION

The simulation study of SVPWM technique was presented and compared with SPWM technique. It was found that by using SVPWM technique, THD content present in inverter output voltage is less as compared with SPWM technique. Table III shows that the utilization of DC bus is l3.55% more for SVPWM compared TO SPWM technique. i. e. SVPWM technique achieved a better utilization of DC bus as compared with SPWM technique. The performance investigation of SPWM inverter and SVPWM inverter fed 1M drive was done. Table IV shows, in case of SVPWM increased rotor speed with reduced error band achieved as compared with SPWM. Also settling time is less for SVPWM as compared with SPWM. It was conclude that results for SVPWM technique are more convenient than SPWM technique.

REFERENCES

[1]   H. W. Van der Broeck, H. C. Skudelny and G. V. Stanke, "Analysis and realization of a pulsewidth modulator based on voltage space vectors," IEEE Trans. Ind. Applicat., vol. 24,no. I, pp. 142-150, Jan.lFeb. 1988.

[2]    S. Fukuda, Y. Iwaji, and H. Hasegawa, "PWM technique for inverter with sinusoidal output current," IEEE Trans. Power Electron., vol. 5, no. I, pp. 54-61, Jan. 1990.

[3]       W. Kolar, H. Ertl, and F. C. Zach, "Inf1uence of the modulation method on the conduction and switching losses of a PWM converter system," IEEE Trans. Ind. Application., vol. 27, no. 6, pp. 1063-1075, Nov.lDec. 1991.

[4]       Joachim Holtz,. "Pulsewidth modulation - A survey," IEEE Trans. on Ind. Electron, vol. 1, pp. 11-18, Dec. 1992.

[5]       B. H. Kwon and B. D. Min, "A fully software-controlled PWM rectifier with current link," IEEE Trans. Ind. Electron., vol. 40, no. 3, pp. 355-363, June 1993.