Finite Control Set Model Predictive Control for Grid Connected Packed U Cells Multilevel Inverter

 ABSTRACT:

This paper presents a Finite Control Set Model Predictive Control (FCS-MPC) for grid-tied Packed U Cells (PUC) Multilevel Inverter (MLI). The system under study consists of a single-phase 3-cells PUC inverter connected to the grid through filtering inductor. The proposed competitive topology allows the generation of 7-level output voltage with reduction of passive and active components compared to the conventional multilevel inverters. The aim of the proposed FCS-MPC technique is to achieve, under various operating conditions, grid-tie current injection with unity power factor and low Total Harmonic Distortion (THD) while balancing the capacitor voltage. Parameters sensitivity analysis was also conducted. The study is conducted on a low power case study single-phase 3-cells PUC inverter and with possible extension to higher number of cells. Theoretical analysis, simulation, and experimental results are presented and compared.

KEYWORDS:

1.      Grid Connection

2.      Model Predictive Control

3.      Packed U Cells Inverter

4.      PUC

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

This paper presented the design, simulations, and experimental validation of a FCS-MPC technique that properly deals with the complex nature of the PUC. Digital simulation for a grid-connected 7-level single-phase PUC inverter was carried out. The simulation results showed that the proposed MPC is capable of simultaneously controlling multi variables of the PUC inverter. The tuning of the weighting factor was conducted successfully based on minimizing the grid current THD as well as the capacitor voltage error. Using the properly selected weighting factor, the MPC has shown an efficient and stable tracking of the reference current at steady state and fast transient response. It is also capable of maintaining the capacitor voltage at its pre-selected and desired level. Parameters sensitivity analysis was carried out and showed that the parameters variation does not have a significant effect on the controller performance. The obtained experimental results confirmed the simulation results and demonstrated that the proposed MPC is effective in controlling the grid current with high steady-state and dynamic tracking performances while keeping balanced capacitor voltage.

 REFERENCES:

[1] H. Abu-Rub, M. Malinowski, K. Al-Haddad, “Power Electronics for Renewable Energy Systems, Transportation and Industrial Applications”, John Wiley & Sons, 2014.

[2] E. Babaei, S. Alilu and S. Laali, "A New General Topology for Cascaded Multilevel Inverters With Reduced Number of Components Based on Developed H-Bridge," in IEEE Trans. Ind. Electron., vol. 61, no. 8, pp. 3932-3939, Aug. 2014.

[3] J. Rodríguez, J.S. Lai, F.Z. Peng, “Multilevel Inverters: A Survey of Topologies, Controls, and Applications”, IEEE Trans. Ind. Electron., vol. 49, no. 4, August 2002.

[4] H. Abu-Rub, J. Holtz, J. Rodriguez and G. Baoming, "Medium-Voltage Multilevel Converters—State of the Art, Challenges, and Requirements in Industrial Applications," IEEE Trans. Ind. Electron., vol.57, no.8, pp.2581-2596, 2010.

[5] J. Chavarria, D. Biel, F. Guinjoan, C. Meza and J. J. Negroni, "Energy-Balance Control of PV Cascaded Multilevel Grid-Connected Inverters Under Level-Shifted and Phase-Shifted PWMs," IEEE Trans. Ind. Electron., vol.60, no.1, pp.98-111, Jan. 2013.

Development of an enhanced multilevel converter using an efficient fundamental switching technique

 ABSTRACT:

This paper presents a new 1-ϕ multilevel inverter topology, which requires a reduced number of switching components, leading to a reduction in the overall expenditure, and enhances reliability for 1-ϕ applications. Without employing any additional H-bridge circuit, the proposed topology can generate both positive and negative polarity output with reduced switching losses and voltage stress. A detailed comparison with some of the prominent multilevel inverters has been presented, which indicates the superiority of the proposed inverter in terms of its design. In addition, to mitigate the harmonics content in the output response, the fundamental sine quantized switching technique has been incorporated into the proposed configuration. The operation and performance of the proposed multilevel inverter have been ascertained by MATLAB/SIMULINK simulation. Finally, a 21-level experimental prototype has been developed to validate theoretical analysis and exhibit the merits of the proposed topology.

KEYWORDS:

1.      Fundamental sine quantized switching technique (FSQST)

2.      Multilevel inverter (MLI)

3.      Total harmonics distortion (THD)

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

 In this work a new modified MLI topology has been proposed with voltage rating of the individual power MOSFETs less than the actual output voltage rating. Also the total number of the semiconductor switches and DC supplies requirement is less. Similarly, it can be inferred that by implementing the FSQST switching technique in the proposed topology, it provides better harmonics profile in the output response while keeping the switching loss minimum. Thus, the proposed inverter is more economic as well as exhibits higher overall efficiency. So, this proposed topology can be used for medium and high power applications.

REFERENCES:

[1] Saccol GA, Giacomini JC, Batschauer AL, Rech C. Comprehensive analysis of singlephase full-bridge asymmetrical flying capacitor inverters. IEEE Trans Ind Appl 2019;55(2):1775–86. https://doi.org/10.1109/TIA.2018.2883549.

[2] Amamra S, Meghriche K, Cherifi A, Francois B. Multilevel inverter topology for renewable energy grid integration. IEEE Trans Industr Electron 2017;64(11):8855–66. https://doi.org/10.1109/TIE.2016.2645887.

[3] Das MK, Jana KC, Sinha A. Performance evaluation of an asymmetrical reduced switched multi-level inverter for a grid-connected pv system. IET Renew Power Gener 2018;12(2):252–63. https://doi.org/10.1049/iet-rpg.2016.0895.

[4] Yang S, Liu Y, Wang X, Gunasekaran D, Karki U, Peng FZ. Modulation and control of transformerless upfc. IEEE Trans Power Electron 2016;31(2):1050–63. https://doi. org/10.1109/TPEL.2015.2416331.

[5] Quraan M, Tricoli P, D’Arco S, Piegari L. Efficiency assessment of modular multilevel converters for battery electric vehicles. IEEE Trans Power Electron 2017;32(3):2041–51. https://doi.org/10.1109/TPEL.2016.2557579.

Sensor-Less Five-Level Packed U-Cell (PUC5) Inverter Operating in Stand-Alone and Grid-Connected Modes

 ABSTRACT:

In this paper a new mode of operation has been introduced for Packed U-Cell (PUC) inverter. A sensor-less voltage control based on redundant switching states is designed for the PUC5 inverter which is integrated into switching process. The sensor-less voltage control is in charge of fixing the DC capacitor voltage at half of the DC source value results in generating symmetric five-level voltage waveform at the output with low harmonic distortion. The sensor-less voltage regulator reduces the complexity of the control system which makes the proposed converter appealing for industrial applications. An external current controller has been applied for grid-connected application of the introduced sensor-less PUC5 to inject active and reactive power from inverter to the grid with arbitrary power factor while the PUC auxiliary DC bus is regulated only by sensor-less controller combined with new switching pattern. Experimental results obtained in stand-alone and grid-connected operating modes of proposed PUC5 inverter prove the fast response and good dynamic performance of the designed sensorless voltage control in balancing the DC capacitor voltage at desired level.

KEYWORDS:

1.      Multilevel Inverter

2.      Packed U-Cell

3.      Sensor-Less Voltage Regulator

4.      PUC5

5.      5-Level Inverter

6.      Power Quality

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

 The PUC5 inverter has been proposed in this paper while the capacitor voltage is balanced without involving any external controller and voltage feedback sensors. The proposed sensor-less voltage controller has been integrated into switching technique to work as open-loop system with reliable results. Moreover, another controller has been designed for the PUC5 inverter to work as unity power factor grid-connected inverter. Low harmonics components in both voltage and current waveforms generated by PUC5, no need to bulky output filters, reliable and good dynamic performance in variable conditions (including change in DC source, load, power amount injected to the grid), requiring no voltage/current sensor in stand-alone mode, low manufacturing costs and miniaturized package due to using less components and etc are interesting advantages of the introduced PUC5 topology which have been proved by experimental results in both stand-alone and grid-connected modes. The presented PUC5 inverter can be a challenging candidate for conventional photovoltaic application inverters

REFERENCES:

[1] H. Abu-Rub, M. Malinowski, and K. Al-Haddad, Power electronics for renewable energy systems, transportation and industrial applications: John Wiley & Sons, 2014.

[2] L. G. Franquelo, J. Rodriguez, J. I. Leon, S. Kouro, R. Portillo, and M. A. M. Prats, "The age of multilevel converters arrives," IEEE Ind. Electron. Mag., vol. 2, no. 2, pp. 28-39, 2008.

[3] 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, 2010.

[4] M. Seyedmahmoudian, S. Mekhilef, R. Rahmani, R. Yusof, and E. T. Renani, "Analytical modeling of partially shaded photovoltaic systems," Energies, vol. 6, no. 1, pp. 128-144, 2013.

[5] H. Mortazavi, H. Mehrjerdi, M. Saad, S. Lefebvre, D. Asber, and L. Lenoir, "A Monitoring Technique for Reversed Power Flow Detection With High PV Penetration Level," IEEE Trans. Smart Grid, vol. 6, no. 5, pp. 2221-2232, 2015.

PUC Converter Review: Topology, Control and Applications

 ABSTRACT:

Packed U-Cell (PUC) converter has been introduced as a 7-level converter in early 2008. Since then, different analysis and projects have been performed on, including various applications such as inverter and rectifier, linear and nonlinear voltage controllers. In this paper, authors try to do a detail review on this topology covering all aspects like topology design in single and three-phase, operation concepts, switching sequences for different multilevel voltage waveform generation, modelling and etc. It is shown that this topology can be comparable to popular multilevel converters (CHB and NPC) in terms of device counts and applications. Moreover, some performed and published works about the PUC are mentioned to show its different industrial applications and some other converter topologies derived based on the PUC. Experimental results are provided to show the good performance of PUC converter in several applications.

KEYWORDS:

1.      Packed U-Cell

2.      Multilevel converter

3.      Active power filter

4.      Active rectifier

5.      Inverter

6.      Power quality

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

 PUC converter generates various voltage levels based on the voltage ratio of its two DC links similar to the CHB topology, while using fewer components. It is an interesting topology in inverter mode due to using only one isolated DC source. It is also attractive in rectifier application because of generating dual output DC terminal in boost and buck mode. As shown in this paper, the PUC converter can be a good candidate for all modes of operation like standalone/grid-connected inverter and rectifier in various applications including PV systems, active filters, wind turbine, electric transportation, battery chargers, MMC, etc.

REFERENCES:

[1] S. Kouro, M. Malinowski, K. Gopakumar, J. Pou, L. G. Franquelo, B. Wu, et al., "Recent advances and industrial applications of multilevel converters," IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2553-2580, 2010.

[2] H. Abu-Rub, J. Holtz, J. Rodriguez, and G. Baoming, "Medium-voltage multilevel converters—State of the art, challenges, and requirements in industrial applications," IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2581-2596, 2010.

[3] H. Abu-Rub, M. Malinowski, and K. Al-Haddad, Power electronics for renewable energy systems, transportation and industrial applications: John Wiley & Sons, 2014.

[4] J. Rodriguez, S. Bernet, P. K. Steimer, and I. E. Lizama, "A survey on neutral point- clamped inverters," IEEE Trans. Ind. Electron., vol. 57, no. 7, pp. 2219- 2230, 2010.

[5] M. Malinowski, K. Gopakumar, J. Rodriguez, and M. A. Perez, "A survey on cascaded multilevel inverters," IEEE Trans. Ind. Electron., vol. 57, no. 7, pp. 2197-2206, 2010.

Newly-Constructed Single Phase MultilevelInverter for Distributed Energy Resources

 ABSTRACT:

Distributed energy resources systems are small power generation tools used to afford substitute solution or added enrichment of traditional electric power system. This paper is mainly concentrated on 1Ø multi-level inverter for Distributed Energy Resources. The objective of this paper is to reduce switches with increase in multi-level outputs which inherently reduces the cost & harmonics. Seven-level inverter with 6 switches and thirteen-level inverter with 8 switches are carried out using MATLAB 7.10 version (Simulink). Total Harmonic Distortion (THD) is analysed for two types of multilevel inverter in MATLAB. For implementing hardware, the circuit is tested in PROTEUS 7.4 version software which helps in troubleshooting real time problem.

KEYWORDS:

1.      Multi-level inverter

2.      Distributed Energy Resources (DER)

3.      Renewable energy

4.       Solar energy

5.      Wind generator

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

This paper reports a substantial saving of switching devices used for a 1Ø multi-level inverter topology that harvests an important multi-level output for DERs. The agreement between the simulated software results and the observed output from the hardware circuit shows clearly that the new multi-level topology for DER works as expected generating desired seven level output using only 6 power switches. Total harmonic Distortion and reduction in switching are appreciable.

 REFERENCES:

[1] Yi-Hung Liao, Member, IEEE, and Ching-Ming Lai, Member, IEEE. Newly-Constructed Simplified Single-Phase Multistring Multilevel Inverter - IEEE Transactions on Power Electronics, VOL. 26, NO. 9, September 2011.

[2] Mariusz Malinowski, Senior Member, IEEE, K. Gopakumar, Senior Member, IEEE, Jose Rodriguez, Senior Member, IEEE, and Marcelo A. Pérez, Member, IEEE. A Survey on Cascaded Multilevel Inverters -IEEE Transactions on Industrial Electronics, VOL. 57, NO. 7, July 2010.

[3] Zhong Du1, Leon M. Tolbert2,3, John N. Chiasson2, and Burak Özpineci3. A Cascade Multilevel Inverter Using a Single DC Source.

[4] Y. Li, D. M. Vilathgamuwa, and P. C. Loh, “Design, analysis, and real time testing of a controller for multibus microgrid system,” IEEE Trans. Power Electron., vol. 19, no. 5, pp. 1195–1204, Sep. 2004.

[5] N . A. Rahim and J. Selvaraj, “Multistring five-level inverter with novel PWM control scheme for PV application,” IEEE Trans. Power Electron., vol. 57, no. 6, pp. 2111–2123, Jun. 2010.

 

Newly-Constructed Simplified Single-Phase Multistring Multilevel Inverter Topology for Distributed Energy Resources

 ABSTRACT:

In the microgrid system, the distributed energy resource (DER)-based single-phase inverter is usually adopted. In order to reduce conversion losses, the key is to save costs and size by removing any kind of transformer as well as reducing the power devices. The objective of this letter is to study a novel five-level multi string inverter topology for DERs-based dc/ac conversion system. In this study, a high step-up converter is introduced as a front-end stage to improve the conversion efficiency of conventional boost converters and to stabilize the output dc voltage of various DERs such as photovoltaic and fuel cell modules for use with the simplified multilevel inverter. The simplified multilevel inverter requires only six active switches instead of the eight required in the conventional cascaded H-bridge multilevel inverter. In addition, two active switches are operated at the line frequency. The studied multi string inverter topology offers strong advantages such as improved output waveforms, smaller filter size, and lower electromagnetic interference and total harmonics distortion. Simulation and experimental results show the effectiveness of the proposed solution.

KEYWORDS:

1.      DC/AC power conversion

2.      Multilevel inverter

SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

 This letter reports a newly constructed single-phase multistring multilevel inverter topology that produces a significant reduction in the number of power devices required to implement multilevel output for DERs. The studied inverter topology offer strong advantages such as improved output waveforms, smaller filter size, and lower EMI and THD. Simulation and experimental results show the effectiveness of the proposed solution.

REFERENCES:

[1] Y. Li, D. M. Vilathgamuwa, and P. C. Loh, “Design, analysis, and realtime testing of a controller for multibus microgrid system,” IEEE Trans. Power Electron., vol. 19, no. 5, pp. 1195–1204, Sep. 2004.

[2] N. Hatziargyriou, H. Asano, R. Iravani, and C. Marnay, “Microgrids,” IEEE Power Energy Mag., vol. 5, no. 4, pp. 78–94, Jul./Aug. 2007.

[3] F.Katiraei, R. Iravani,N.Hatziargyriou, andA.Dimeas, “Microgridsmanagement,” IEEE Power Energy Mag., vol. 6, no. 3, pp. 54–65, May/Jun. 2008.

[4] C. L. Chen,Y.Wang, J. S. Lai,Y. S. Lee, andD.Martin, “Design of parallel inverters for smooth mode transfer microgrid applications,” IEEE Trans. Power Electron., vol. 25, no. 1, pp. 6–15, Jan. 2010.

[5] C. T. Pan, C. M. Lai, and M. C. Cheng, “A novel high step-up ratio inverter for distributed energy resources (DERs),” in Proc. IEEE Int. Power Electron. Conf., 2010, pp. 1433–1437.

Multilevel inverter topology based on series connected switched sources

 ABSTRACT:

A new topology for multilevel DC–AC conversion is presented in this study. It consists of isolated symmetric input DC sources alternately connected in opposite polarities through power switches. The structure allows synthesis of multilevel waveform using reduced number of power switches as compared to the classical topologies. The working principle of the proposed topology is explained with the help of a single-phase five-level inverter. Simulation studies are carried out in MATLAB/Simulink environment and experimental validations are obtained on a laboratory prototype. An exhaustive comparison of the proposed topology against the classical cascaded H-bridge topology indicates reduction in number of power switches, losses, installation area and converter cost.

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

 This paper proposes a novel topology for MLIs to reduce the number of power switches as compared to the classical topologies. It consists of floating input DC sources, which contribute individually or in series with other sources for synthesis of multilevel waveform. All input DC sources are symmetrical and no bidirectional power switches are required. Comparisons carried out in the paper show that the proposed topology requires lesser number of power components as compared to the classical topologies. For ‘N’ number of output levels, the proposed topology uses ‘N + 1’ power switches whereas classical topologies use ‘2(N − 1)’ power switches. However, reduction in number of switches leads to increased power rating of ‘N − 3’ switches. Conduction losses in the proposed topology are expected to be lesser. Comparison with the classical CHB topology also indicates that the proposed topology is relatively more economical. However, requirement of isolated input DC sources may restrict the usage of the proposed topology to specific applications. Simulation studies are performed on five-level inverter based on proposed structure and a laboratory prototype is executed for it. Satisfactory responses are observed in the prototype. It is also seen that in the event of source failure, it continues to operate with remaining sources.

REFERENCES:

1 Franquelo, L.G., Rodriguez, J., Leon, J.I., Kouro, S., Portillo, R., Prats, M.A.M.: ‘The age of multilevel converters arrives’, IEEE Ind. Electron. Mag., 2008, 2, (2), pp. 28–39

2 Rodriguez, J., Franquelo, L.G., Kouro, S., et al.: ‘Multilevel converters: an enabling technology for high-power applications’, Proc. IEEE, 2009, 97, (11), pp. 1786–1817

3 Rodriguez, J., Bernet, S., Wu, B., Pontt, J.O., Kouro, S.: ‘Multilevel voltage-source-converter topologies for industrial medium-voltage drives’, IEEE Trans. Ind. Electron., 2007, 54, (6), pp. 2930–2945

4 Liu, Y., Luo, F.L.: ‘Multilevel inverter with the ability of self-voltage balancing’, IEE Proc. Electr. Power Appl., 2006, 153, (1), pp. 105–115

5 De, S., Banerjee, D., Siva Kumar, K., Gopakumar, K., Ramchand, R., Patel, C.: ‘Multilevel inverters for low-power application’, IET Power Electron., 2011, 4, (4), pp. 384–392