Evaluation of Level-Shifted and Phase-Shifted PWM Schemes for Seven Level Single-Phase Packed U Cell Inverter

ABSTRACT:

 An evaluation of level shifted and phase shifted triangular and saw tooth carrier modulation schemes for a seven level packed U cell (PUC) inverter is presented in this paper. The investigated PUC is the recently introduced topology for multilevel inverter having reduced switch count in comparison to the conventional topologies of multilevel inverters. The PUC inverter has six switches for 7 level inverter which is very less in comparison to the conventional topologies. In this paper, the level-shifted pulse width modulation (LS-PWM) and phase-shifted PWM (PS-PWM) for triangular and saw tooth carrier are presented and compared. A comparative harmonic analysis for all the cases is performed and results are presented in the paper. The difference in harmonics of the two modulation methods given by the theoretical approach for both the carrier is validated by the experimental results. DC voltage controller and load current controller of the PUC inverter are also designed and presented. The investigated PUC topology is tested in dynamic and steady state conditions and results obtained are presented. The analysis is done and validated using simulation in MATLAB® Simulink environment and experimental approaches using FPGA platform.

 KEYWORDS:

1.      Level shift

2.      Multilevel inverter

3.      Modulation

4.       Phase shift

5.       PI controller

6.      PUC inverter

SOFTWARE: MATLAB/SIMULINK

CONCLUSION

The paper has presented the comparison of different PWM schemes which can be applied to the PUC inverter. Investigating the suitable modulation schemes is very essential with respect to local grid integration, as the power quality is directly dependent on THD. Triangular carrier based PWM schemes is exhibiting the better result than the saw tooth carrier based PWM schemes as the triangular level shifted carrier PWM scheme is better as compared to saw tooth level shifted carrier because in triangular level shifted carrier both edges (falling and rising) of pulses are modulated which improves the harmonic spectrum. However, in the saw tooth level shifted carrier only rising edges are modulated. Hence triangular level shifted carrier PWM scheme can be applied for integrating the PUC inverter with PV and local grid systems. Triangular level shifted carrier PWM scheme for PUC inverter has been suggested based on observing the THD in voltage and current which are respectively just 17.92% and 2.43%. The whole system i.e. solar panel, boost converter with PUC inverter will be very cost effective, besides having good reliability and power quality as it has the minimum number of power electronics devices compared to previously introduced multilevel inverter topologies. With reduced number of capacitors and power switches seven levels of voltages have been achieved for PUC inverter.

REFERENCES:

[1] F. A. Rahman, M. M. A. Aziz, R. Saidur, W. A. A. Bakar, M. R. Hainin, R. Putrajaya, and N. A. Hassan, “Pollution to solution: Capture and sequestration of carbon dioxide (CO2) and its utilization as a renewable energy source for a sustainable future”, Renewable and Sustainable Energy Reviews,vol. 71, pp. 112-126, May 2017.

[2] Y. Yang, A. Sangwongwanich, and F. Blaabjerg, “Design for reliability of power electronics for grid-connected photovoltaic systems,” in CPSS Transactions on Power Electronics and Applications, vol. 1, no. 1, pp. 92-103, Dec. 2016..

[3] J. Rodriguez, J.-S. Lai, and F. Z. Peng, “Multilevel inverters: a survey of topologies, controls, and applications,” Industrial Electronics, IEEE Transactions on, vol. 49, pp. 724-738, 2002.

[4] Q. M. Attique, Y. Li, and K. Wang, “A survey on space-vector pulse width modulation for multilevel inverters,” in CPSS Transactions on Power Electronics and Applications, vol. 2, no. 3, pp. 226-236, Sept. 2017.

[5] Z. Mohzani, B. P. McGrath, and D. G. Holmes, “A generalized natural balance model and balance booster filter design for three-level Neutral- Point-Clamped converters,” in IEEE Transactions on Industry Applications, vol. 51, no. 6, pp. 4605-4613, Nov.-Dec. 2015.

Comprehensive Review on Solar, Wind and Hybrid Wind-PV Water Pumping Systems-An Electrical Engineering Perspective

ABSTRACT:

 In India, the demand for water is continuously increasing due to the growing population. Approximately 16.5% of all country’s electricity used to pump this water is from fossil fuels leading to increased pump Life Cycle Cost (LCC) and Green House Gas (GHG) emissions. With the recent advancement in power electronics and drives, renewables like solar photovoltaic and wind energy are becoming readily available for water pumping applications resulting in the reduction of GHG emissions. Recently, research towards AC motor based Water Pumping Systems (WPS) has received a great emphasis owing to its numerous merits. Further, considering the tremendous acceptance of renewable sources, especially solar and wind, this paper provides a detailed review of single-stage and multi-stage WPS consisting of renewable source powered AC motors. The critical review is performed based on the following figure of merits, including the type of motor, power electronics interface and associated control strategies. Also, to add to the reliability of solar PV WPS, hybrid Wind-PV WPS will be discussed in detail. Readers will be presented with the state-of-the-art technology and research directions in Renewable Energy-based WPS (REWPS) to improve the overall system efficiency and hence reduce the payback period.

KEYWORDS:

 

1.      AC motor

2.       Hybrid wind-PV system

3.       Multi-stage solar water pump

4.      Pump life cycle cost

5.       Single-stage solar water pump

6.       Water pumping system

SOFTWARE: MATLAB/SIMULINK

CONCLUSION

This paper has attempted to consolidate the research in renewable energy-based water pumping systems. Exhaustive research with the primary focus in the field of electrical engineering like power electronics interface, the motor used for pumping and mainly the control strategy employed for the effective energy utilization of the renewables is presented. The following are the conclusions of this work:

• Investigations conducted on multi-stage SPWPSs, single-stage SPWPSs, Wind WPSs and hybrid Wind-PV systems have been reviewed in detail.

• In each of the systems mentioned above, various research avenues have been conferred to the reader namely, the power electronics interface, MPPT algorithms, type of the motor, motor control algorithms and sensors used for the algorithms.

• Findings of several investigations conducted to compare the performance of multi-stage WPS with single-stage WPS have been presented to weigh the performance of the WPSs.

• Niche areas in REWPSs have been indicated to readers to pursue future research.

This review paper is an effort to guide researchers consolidating work in the area of the REWPS with an emphasis on aspects of electrical engineering (type of motor, power electronics interface and control strategies). In a country like India, which suffers irregular monsoons, harnessing renewable energy sources efficiently to fulfill the requirement of water will be the dire need of the near future. Also, the geographical location of the nation is favorable to produce energy from renewable sources like sunlight and wind. Hence, the authors are in the developmental work of control strategies for REWPSs.

 REFERENCES:

[1] K. B. LTD. (2019, Mar. 28). Life Cycle Cost Analysis – Systematic Approach. [Online]. Available: http://ashraeindia.org/pdf/KBL presenta-tion3.pdf/.

[2] C. Gopal, M. Mohanraj, P. Chandramohan, and P. Chandrasekar, “Renewable energy source water pumping systems—A literature review,” in Renewable and Sustainable Energy Reviews, vol. 25, no. 5, pp. 351–370, Sept. 2013.

[3] P. Periasamy, N. Jain, and I. Singh, “A review on development of photovoltaic water pumping system,” in Renewable and Sustainable Energy Reviews, vol. 43, pp. 918–925, Mar. 2015.

[4] S. Chandel, M. N. Naik, and R. Chandel, “Review of solar photovoltaic water pumping system technology for irrigation and community drinking water supplies,” in Renewable and Sustainable Energy Reviews, vol. 49, no. 9, pp. 1084–1099, May 2015.

[5] R. Rawat, S. Kaushik, and R. Lamba, “A review on modeling, design methodology and size optimization of photovoltaic based water pumping, standalone and grid connected system,” in Renewable and Sustainable Energy Reviews, vol. 57, pp. 1506–1519, Jan. 2016.

Bidirectional Isolated Dual-Active-Bridge (DAB) DC-DC Converters Using 1.2-kV 400-A SiC-MOSFET Dual Modules

 ABSTRACT:

 This paper describes the 750-Vdc, 100-kW, 20- kHz bidirectional isolated dual-active-bridge (DAB) dc dc converters using four 1.2-kV 400-A SiC-MOSFET dual modules with or without Schottky barrier diodes (SBDs). When no SBD is integrated into each dual module, the conversion efficiency from the dc-input to the dc-output terminals is accurately measured to be 98.0% at the rated-power (100 kW) operation, and the maximum conversion efficiency is as high as 98.8% at 41-kW operation, excluding the gate drive and control-circuit losses from the total power loss. The bidirectional isolated DAB dc-dc converters are so flexible that series and/or parallel connections of their individual input and output terminals make it easy to expand the voltage and current ratings for various applications such as the so-called “solid-state transformer” or “power electronic transformer.”

KEYWORDS:

1.      Bidirectional isolated dc-dc converters

2.      Conversion efficiency

3.      Dual-active-bridge configuration

4.      SiC MOSFET modules

SOFTWARE: MATLAB/SIMULINK

CONCLUSION

This paper has designed, built, and tested two 750-Vdc, 100-kW, 20-kHz bidirectional isolated dual-active-bridge (DAB) dc-dc converters using four 1.2-kV, 400-A SiC-MOSFET dual modules with and without SBDs are used, the maximum conversion efficiency from the dc- input terminals to the dc-output terminals is as high as 98.8. at 41 kW, and 98.0% at 100 kW, which are calculated from the accurately-measured overall power loss excluding gate drive and control circuit losses. When the next generation trench-gate Sic-MOSFET modules come across, the conversion efficiency of a well designed DAB dc-dc converter is expected to be higher than 99% in a broad power range, even at the rated power. Series and/or parallel connections of multiple DAB dc-dc converters would make it easy to expand the voltage and/or current ratings as if the converter were operating as a single high-power DAB dc-dc converter. In particular, the input series and output-parallel connections show considerable promise as a dc-dc converter for medium-voltage high power battery energy storage systems and an interface circuit between two dc power networks with different dc voltages.

REFERENCES:

[1] R. W. De Doncker, D. M. Divan, and M. H. Kheraluwala, “A three phase soft-switched high-power-density dc/dc converter for high power applications,” IEEE Trans. Ind. Appl., vol. 27, no. 1, pp.63-73,Jan/Feb.1991.

 [2] M. H. Kheraluwala, R. W. Gascoigne, D. M. Divan, and E. D. Baumann, “Performance characterization of a high-power dual active bridge dctodc converter,” IEEE Trans. Ind. Appl.,vol.28,no.6, pp. 1294–1301, Nov./Dec. 1992.

[3] R. L Steigerwald, R. W. De Doncker, and M. H. Kheraluwala, “A comparison of high-power dc-dc soft-switched converter topologies,” IEEE Trans. Ind. Appl., vol. 32, no. 5, pp. 1139–1145, Sept/Oct.1996.

[4] S. Inoue and H. Akagi, “A bidirectional isolated dc-dc converter as a core circuit of the next-generation medium-voltage power conversion system,” IEEE Trans. Ind. Appl., vol. 22, no. 2, pp. 535–542, Mar. 2007.

[5] S. Inoue and H. Akagi, “A bidirectional dc-dc converter for an energy storage system with galvanic isolation,” IEEE Trans. Power Electron vol.22,no.6,pp.2299-2306.Nov.2007

Analysis of a Modified Single Phase Multilevel Cascaded Inverter Circuit

ABSTRACT:

 

A modified circuit of single phase five level cascaded inverter state of art design topology is discussed. The modified circuit has reduced number of switches and a comparison of the total harmonic distortion with various pulse width modulation techniques was carried out. A multicarrier sinusoidal pulse width modulation approach is used to control the distortion in the inverter. Several types of multi carrier pulse width modulation techniques have been analyzed in this paper. For higher modulation index value the Phase Disposition offers the lowest level of Total harmonic distortion. To validate the objective MATLAB/Simulink simulation software was used and it has been justified by using the experimental results.

KEYWORDS:

 

1.      Sinusoidal pulse width modulation(SPWM)

2.      Cascaded multi level inverter (CMLI)

3.      Total harmonic distortion (THD)

 

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

By using state of art design the proposed converter circuit was designed and the experimental verification of simulation results was carried out. To remove the harmonics, SPWM was used and the overall performance of the system was improved. Results obtained show the successful harmonics elimination. By utilizing the different configuration of multilevel SPWM techniques the harmonics are reduced significantly. For higher modulation index value the Phase Disposition offers the lowest level of Total harmonic distortion.

REFERENCES:

[1] C. Govindaraju1 and K. Baskaran, “Performance Improvement of Multiphase Multilevel Inverter Using Hybrid Carrier Based Space Vector Modulation”, International Journal on Electrical Engineering and Informatics, vol. 2, pp. 137- 149, 2014.

[2] C.Govindaraju and Dr.K.Baskaran, “Optimized Hybrid Phase Disposition PWM Control Method for Multilevel Inverter”, International Journal of Recent Trends in Engineering, vol. 1, no. 3, pp129-134, May 2014.

[3] Zhong Du1, Leon M. Tolbert2,3, John N. Chiasson2, and Burak Özpineci3, “A Cascade Multilevel Inverter Using a Single DC Source”, Applied Power Electronics Conference and Exposition, APEC '06. Twenty-First Annual IEEE, pp. 426-430, 2006.

[4] P. Thongprasri,“A 5-Level Three-Phase Cascaded Hybrid Multilevel Inverter”, International Journal of Computer and Electrical Engineering, Vol. 3, No. 6, December 2011, pp 789-794.

[5] C.Kiruthika1,T.Ambika,Dr.R.Seyezhai, “simulation of cascaded multilevel inverter using hybrid pwm technique”, International Journal of Systems, Algorithms & Applications Volume 1, Issue 1, December 2011, pp-18-21.

 

A Voltage and Frequency Droop Control Method forParallel Inverters

 ABSTRACT: 

In this paper, a new control method for the parallel operation of inverters operating in an island grid or connected to an infinite bus is described. Frequency and voltage control, including mitigation of voltage harmonics, are achieved without the need for any common control circuitry or communication between inverters. Each inverter supplies a current that is the result of the voltage difference between a reference ac voltage source and the grid voltage across a virtual complex impedance. The reference ac voltage source is synchronized with the grid, with a phase shift, depending on the difference between rated and actual grid frequency. A detailed analysis shows that this approach has a superior behavior compared to existing methods, regarding the mitigation of voltage harmonics, short-circuit behavior and the effectiveness of the frequency and voltage control, as it takes the to line impedance ratio into account. Experiments show the behavior of the method for an inverter feeding a highly nonlinear load and during the connection of two parallel inverters in operation.

KEYWORDS:

 

1.      Autonomous power systems

2.      Converter control

3.      Dispersed generation

4.      Finite output-impedance ac voltage source emulation

5.      Frequency and voltage droops

6.      Harmonics

7.       Parallel connection

8.      Power quality

9.      Microgrids

10.  Stand-alone systems

11.  Uninterruptible power supplies (UPS)

12.  Virtual impedance

13.  Voltage source inverter

14.   Mixed voltage-current control

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

A time-domain method for controlling voltage and frequency using parallel inverters connected to the mains or in an island grid is developed. By imitating a voltage source with a complex finite-output impedance, voltage droop control is obtained. Frequency droop control results from synchronizing the power source with the grid, with a phase angle difference that depends on the difference between rated and actual grid frequency. Compared to existing techniques, the described method exhibits superior behavior, considering the mitigation of voltage harmonics, the behavior during short-circuit and, in the case of a non-negligible line resistance, the “efficient” control of frequency and voltage. Two experiments are included to show the described behavior.

REFERENCES:

[1] A. Tuladhar, H. Jin, T. Unger, and K. Mauch, “Parallel operation of single phase inverter modules with no control interconnections,” in Proc. IEEE-APEC’97 Conf., Feb. 23–27, 1997, vol. 1, pp. 94–100.

[2] E. A. A. Coelho, P. C. Cortizo, and P. F. D. Garcia, “Small-signal stability for parallel-connected inverters in stand-alone AC supply systems,” IEEE Trans. Ind. Appl., vol. 38, no. 2, pp. 533–542, Mar./Apr. 2002.

[3] M. C. Chandorkar, D. M. Divan, and R. Adapa, “Control of parallel connected inverters in standalone AC supply systems,” IEEE Trans. Ind. Appl., vol. 29, no. 1, pp. 136–143, Jan./Feb. 1993.

[4] A. Engler, “Regelung von Batteriestromrichtern in modularen und erweiterbaren Inselnetzen,” Ph.D. dissertation, Dept. Elect. Eng., Univ. Gesamthochschule Kassel, Kassel, Germany, 2001.

[5] M. Hauck and H. Späth, “Control of three phase inverter feeding an unbalanced load and operating in parallel with other power sources,” in Proc. EPE-PEMC’02 Conf., Sep. 9–11, 2002.

Step-Up DC–DC Converters: A Comprehensive Review of Voltage-Boosting Techniques, Topologies, and Applications

ABSTRACT:

DC–DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which fundamental energy storing elements (inductors and capacitors) and/or transformers in conjunction with switch(es) and diode(s) are utilized in the circuit. These techniques include switched capacitor (charge pump), voltage multiplier, switched inductor/voltage lift, magnetic coupling, and multistage/-level, and each has its own merits and demerits depending on application, in terms of cost, complexity, power density, reliability, and efficiency. To meet the growing demand for such applications, new power converter topologies that use the above voltage-boosting techniques, as well as some active and passive components, are continuously being proposed. The permutations and combinations of the various voltage-boosting techniques with additional components in a circuit allow for numerous new topologies and configurations, which are often confusing and difficult to follow. Therefore, to present a clear picture on the general law and framework of the development of next-generation step-up dc–dc converters, this paper aims to comprehensively review and classify various step-up dc–dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc–dc converters are presented and summarized with comparative study of different voltage-boosting techniques.

 

KEYWORDS:

1.      Coupled inductors

2.      Multilevel converter

3.      Multistage converter

4.      Pulse width modulated (PWM) boost converter

5.      Switched capacitor (SC)

6.      Switched inductor

7.      Switched mode step-up dc–dc converter

8.      Transformer

9.      Voltage lift (VL)

10.  Voltage multiplier

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The ongoing technological progress in high-voltage step-up dc–dc converter has five primary drivers—energy efficiency, power density, cost, complexity, and reliability—all of which also influence each other to some extent. Table X, along with the spider wave diagram in Fig. 34, provides a comparative summary of various voltage-boosting techniques in terms of their major characteristics (i.e., power level, cost, reliability, efficiency, power density, weight, integration, and complexity).This view facilitates quick selection between related alternatives for special load and application requirements. Each voltage boosting technique has its own unique features and suitable applications, and there is no one-size-fits-all solution. Nevertheless, it is generally not fair to permanently favor any particular technique or solution. The converter topology and control method, which was seen as complex and inefficient a decade back, has now become a key solution for many industries and applications. In this manner, new topologies based on different and often merged voltage-boosting techniques will continue to appear in order to meet and improve the performance of different applications. Thanks to the progress in power-semiconductor devices, new widebandgap devices (GaN, SiC, etc.), advanced magnetic materials, high-performance digital control platforms, and advanced design and packaging including thermal management (3-D integrated) have all become a reality. These advances will undeniably enablemore powerful and advanced power converter solutions for the next generation of power conversion systems. Overall, the authors hope that this comprehensive survey will be a useful resource to help both academic and industry readers comprehend step-up dc–dc converter topologies and identify their respective pros and cons.

REFERENCES:

[1] T. G. Wilson, “The evolution of power electronics,” IEEE Trans. Power Electron., vol. 15, no. 3, pp. 439–446, May 2000.

[2] B. K. Bose, “The past, present, and future of power electronics,” IEEE Ind. Electron. Mag., vol. 3, no. 2, pp. 7–11, Jun. 2009.

[3] M. H. Rashid, Power Electronics Handbook: Devices Circuitsand Application, 3rd ed. Burlington, MA, USA: Elsevier, 2011.

[4] M.K.Kazimierczuk, Pulse-WidthModulated DC-DC Power Converters. Chichester, U.K.: Wiley, 2008.

[5] R.W. Erickson and D. Maksimovic, Fundamentals of Power Electronics, 2nd ed. Norwell, MA, USA: Kluwer, 2001.

Single-Phase Shunt Active Filter Interfacing Renewable Energy Sources with the Power Grid

ABSTRACT:

This paper presents a single-phase Shunt Active Filter combined with a Maximum Power Point Tracker (MPPT) connected to a solar panel array. The Shunt Active Filter’s power stage consists of a two-leg IGBT inverter commanded by a Digital Signal Processor (DSP) with control based on the Theory of Instantaneous Reactive Power (p-q Theory). The MPPT is based on a step-up circuit commanded by a DSP with MPPT Algorithm implemented. The output of the MPPT circuit is connected to the DC side of the Shunt Active Filter. The system is capable of compensating power factor and current harmonics, and at the same time, using the same inverter, injecting in the power grid electric energy produced by solar panels, regulated by the MPPT. There will be presented results of the system operating in an electrical installation under different conditions, as well as the hardware configuration and specifications.

 

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

This paper presented experimental results of a single-phase Shunt Active Filter combined with a MPPT, injecting energy in the electric grid produced by a solar panel array. The results show the performance of the Shunt Active Filter operating alone, and also the complete system behavior in compensation and energy injection tasks simultaneously. The presented configuration shows some advantages over the traditional ones since it gathers functionalities of different equipments using the same hardware to accomplish the different tasks. The only drawback of the presented configuration is that the power inverter has to be increased because the injected current is composed by two components: a component that represents the renewable energy to inject in the electric grid and a component to compensate harmonics and power factor of the facility.The presented Active Power Filters are currently in industrialization process by the company EFACEC SGPS S.A.

REFERENCES:

 [1] L. Gyugi and E. C. Strycula, “Active AC Power Filters”, IEEE-IAS Annual Meeting Record, 1976, pp. 529-535.

[2] J. G. Pinto, R. Pregitzer, Luís F. C. Monteiro, João L. Afonso, “3 Phase 4 Wire Shunt Active Power Filter with Renewable Energy Interface”, Proceedings of ICREPQ’07- International Conference on Renewable Energies and Power Quality, 28-30 March 2007, Seville, Spain, ISBN:978-84-611-4707-6.

[3] H. Akagi, Y. Kanazawa, A. Nabae, “Generalized Theory of the Instantaneous Reactive Power in Three-Phase Circuits”, IPEC'83 - Int. Power Electronics Conf., Tokyo, Japan, 1983, pp. 1375-1386.

[4] H. Akagi, Y. Kanazawa, A. Nabae, “Instantaneous Reactive Power Compensator Comprising Switching Devices without Energy Storage Components”, IEEE Trans. Industry Applic., vol. 20, May/June 1984.

[5] E. H. Watanabe, R. M. Stephan, M. Aredes, “New Concepts of Instantaneous Active and Reactive Powers in Electrical Systems with Generic Loads”, IEEE Trans. Power Delivery, vol. 8, no. 2, April 1993,pp. 697-703.