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

A Novel Multilevel Inverter Based onSwitched DC Source

ABSTRACT:

This paper presents a multilevel inverter that has been conceptualized to reduce component count, particularly for a large number of output levels. It comprises floating input dc sources alternately connected in opposite polarities with one another through power switches. Each input dc level appears in the stepped load voltage either individually or in additive combinations with other input levels. This approach results in reduced number of power switches as compared to classical topologies. The working principle of the proposed topology is demonstrated with the help of a single-phase five-level inverter. The topology is investigated through simulations and validated experimentally on a laboratory prototype. An exhaustive comparison of the proposed topology is made against the classical cascaded H-bridge topology.

KEYWORDS:

1.      Classical topologies

2.      Multilevel inverter (MLI)

3.      Pulse width modulation (PWM)

4.      Reduced component count

5.      Total harmonic distortion (THD)

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

 As MLIs are gaining interest, efforts are being directed toward reducing the device count for increased number of output levels. A novel topology for MLIs has been proposed in this paper to reduce the device count. The working principle of the proposed topology has been explained, and mathematical formulations corresponding to output voltage, source currents, voltage stresses on switches, and power losses have been developed. Simulation studies performed on a five-level inverter based on the proposed structure have been validated experimentally. Comparison of the proposed topology with conventional topologies reveals that the proposed topology significantly reduces the number of power switches and associated gate driver circuits. Analytical comparisons on the basis of losses and switch cost indicate that the proposed topology is highly competitive. The proposed topology can be effectively employed for applications where isolated dc sources are available. The advantage of the reduction in the device count, however, imposes two limitations: 1) requirement of isolated dc sources as is the case with the CHB topology and 2) curtailed modularity and fault-tolerant capabilities as compared to the CHB topology

REFERENCES:

[1] S. Kouro, M. Malinowski, K. Gopakumar, J. Pou, L. Franquelo, B. Wu, J. Rodriguez, M. Perez, and J. Leon, “Recent advances and industrial applications of multilevel converters,” IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2553–2580, Aug. 2010.

[2] G. Buticchi, E. Lorenzani, and G. Franceschini, “A five-level single-phase grid-connected converter for renewable distributed systems,” IEEE Trans. Ind. Electron., vol. 60, no. 3, pp. 906–918, Mar. 2013.

[3] J. Rodriguez, J.-S. Lai, and F. ZhengPeng, “Multilevel inverters: A survey of topologies, controls, applications,” IEEE Trans. Ind. Electron., vol. 49, no. 4, pp. 724–738, Aug. 2002.

[4] S. De, D. Banerjee, K. Siva Kumar, K. Gopakumar, R. Ramchand, and C. Patel, “Multilevel inverters for low-power application,” IET Power Electronics, vol. 4, no. 4, pp. 384–392, Apr. 2011.

[5] M. Malinowski, K. Gopakumar, J. Rodriguez, and M. A. Pérez, “A surveyon cascaded multilevel inverters,” IEEE Trans. Ind. Electron., vol. 57,no. 7, pp. 2197–2206, Jul. 2010.

Analysis and Design of a Standalone Electric Vehicle Charging Station Supplied by Photovoltaic Energy

ABSTRACT:

Nowadays, there is a great development in electric vehicle production and utilization. It has no pollution, high efficiency, low noise, and low maintenance. However, the charging stations, required to charge the electric vehicle batteries, impose high energy demand on the utility grid. One way to overcome the stress on the grid is the utilization of renewable energy sources such as

photovoltaic energy. The utilization of standalone charging stations represents good support to the utility grid. Nevertheless, the electrical design of these systems has different techniques and is sometimes complex. This paper introduces a new simple analysis and design of a standalone charging station powered by photovoltaic energy. Simple closed-form design equations are derived, for all the system components. Case-study design calculations are presented for the proposed charging station. Then, the system is modeled and simulated using Matlab/Simulink platform. Furthermore, an experimental setup is built to verify the system physically. The experimental and simulation results of the proposed system are matched with the design calculations. The results show that the charging process of the electric vehicle battery is precisely steady for all the PV insolation disturbances. In addition, the charging/discharging of the energy storage battery responds perfectly to store and compensate for PV energy variations.

KEYWORDS:

1.      Electric vehicle

2.      Charging station;

3.      Photovoltaic

4.      Maximum power point tracking

SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

 An isolated EV charging station based on a PV energy source is proposed. The system consists of PV panel, boost converter, ESS batteries, two DC/DC charging converters, and an EV battery. The control system consists of three controllers named the MPPT, the EV charger, and the storage converter controller. PI voltage and current controllers are adapted to control charging/discharging of the ESS system and the EV charger as well. The system is simulated and implemented physically. A single-chip PIC18F4550 microcontroller is utilized to realize the system controllers. New simple energy and power analyses procedure has been introduced. Hence, closed-form equations have been derived to help in the design phase. Complete design of the system, including the ESS size, the PV rating, and the filter components, has been proposed. Simulation and experimental results are very close and verify the effectiveness of the proposed system. At different insolation levels, the results show that the charging process of the EV battery is steady without any disturbance. However, the charging/discharging of the ESS battery responds perfectly to store and compensate for PV energy variations. The current and voltage controllers of the converters give good responses and track their references well. In addition, the MPPT controller tracks the peak conditions of the PV precisely.

 REFERENCES:

1. Irle, R. Global EV Sales for the 1st Half of 2019. EV Volumes. 2019. Available online: http://www.ev-volumes.com/country/ total-world-plug-in-vehicle-volumes/ (accessed on 20 November 2019).

2. Sun, X.; Li, Z.;Wang, X.; Li, C. Technology Development of Electric Vehicles: A Review. Energies 2020, 13, 90. [CrossRef]

3. Luc, Vehicles & Charging Tips. Fastned. 2019. Available online: https://support.fastned.nl/hc/en-gb/sections/115000180588 -Cars-charging-tips- (accessed on 30 March 2019).

4. Richard, L.; Petit, M. Fast charging station with a battery storage system for EV: Optimal integration into the grid. In Proceedings of the 2018 IEEE Power & Energy Society General Meeting (PESGM), Portland, OR, USA, 5–10 August 2018; pp. 1–5.

5. Chakraborty, S.; Vu, H.-N.; Hasan, M.M.; Tran, D.-D.; Baghdadi, M.E.; Hegazy, O. DC-DC Converter Topologies for Electric Vehicles, Plug-in Hybrid Electric Vehicles and Fast Charging Stations: State of the Art and Future Trends. Energies 2019, 12, 1569. [CrossRef]