Modified Phase-Shifted PWM Scheme forReliability Improvement in Cascaded H-BridgeMultilevel Inverters

ABSTRACT:

 The cascaded H-bridge multilevelinverter (CHMI) is a modular structure that consists of many power semiconductor switches.With this increase in the number of power semiconductor switches, it is hard to predict and handle the failure of the devices, and hence reliability of CHMI decreases. The major cause of power semiconductor switch failure is junction temperature that is produced by power losses. The study proposes a multi-carrierpulse-width modulation (PWM) scheme for reduction in switching losses of CHMI. In the proposed modulation scheme, the two legs conduct switching operation at different frequencies for switching reduction. One leg conducts switching operation with high frequency, while the other leg conducts switching operation with fundamental frequency. The switching operations with different frequencies cause unbalanced switching loss to each leg. Therefore, the junction temperature that is based on power losses leads to different life-times for the power semiconductor switch. Additionally, the switching frequency of the two legs is alternated to evenly distribute switching losses and junction temperature. Simulation and experimental results verify the performance of the proposed PWM scheme.

KEYWORDS:                                                                   

1.      Cascaded H-bridge multilevel inverter

2.      Phase-shifted pulse-width modulationscheme

3.      Reliability of power semiconductor switch

4.      Switching loss reduction

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

This paper proposes a modulation method for a 5-level three phase CHMI to extend the life-time and improve reliability of power semiconductor switches. The proposed method is based on the PS-PWM scheme and decreased power losses via the clamped modulation period. The existing reference voltage waveform is modified into two-type reference voltage waveforms to inject the clamped modulation period. The clamped signal reduces power loss, and other signal is reconfigured to maintain the quality of output waveforms such as the level of output voltage. Reduced power losses decrease the temperature of the power semiconductor switch, and thus the expected life-time of the powersemiconductor switch is extended by using the proposed modulation method. Additionally, the proposed modulation scheme considers the power loss balance among the switches in the same cell to improve the reliability of the CHMI. The rotation method with 1/4 period is applied to proposed scheme for even switching loss and temperature among switches. Therefore, the all switches in proposed method are decreased temperature and increased life-time evenly. The performance of the proposed method is verified via simulation and experimental results.

REFERENCES:

[1] B.Wu, High-Power Converter and AC Drives. Hoboken, NJ, USA:Wiley,2006.

[2] D. Karwatzki and A. Mertens, ``Generalized control approach for a class of modular multilevel converter topologies,'' IEEE Trans. Power Electron., vol. 33, no. 4, pp. 2888_2900, Apr. 2018.

[3] S. Kouro, M. Malinowski, K. Gopakumar, J. Pou, L. G. Franquelo, B.Wu, J. Rodriguez, M. A. Pérez, and J. I. Leon, ``Recent advances and industrial applications of multilevel converters,'' IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2553_2580, Aug. 2010.

[4] J. Rodriguez, S. Bernet, B. Wu, J. O. Pontt, and S. Kouro, ``Multilevel Voltage-Source-Converter topologies for industrial medium-voltage drives,'' IEEE Trans. Ind. Electron., vol. 54, no. 6, pp. 2930_2945, Dec. 2007.

[5] G. P. Adam, I. A. Abdelsalam, K. H. Ahmed, and B.W.Williams, ``Hybrid multilevel converter with cascaded H-bridge cells for HVDC applications: Operating principle and scalability,'' IEEE Trans. Power Electron., vol. 30, no. 1, pp. 65_77, Jan. 2015.

High Speed SRM Using Vector Control for Electric Vehicle

ABSTRACT:

The high speed motor is effective to realize downsizing motor in an electric vehicle (EV). Switched Reluctance Motor (SRM) is possible to the high speed drive because the rotor structure has simple and robust. However, the vibration and the acoustic noise are large from the drive principle. Moreover, the conventional complicated current excitation results in the difficulty of the torque controller design. To overcome these problems, the vector control has been proposed for SRM drive. However, the vector control has not been applied to the SRM in the high speed drive. In this paper, the drive conditions such as switching frequency, bus voltage for driving the SRM in the high speed region are clarified. It is shown that the proposed SRM can be driven by the vector control in the high speed region and can realize low vibration.

KEYWORDS:

1.      Switched reluctance motor

2.      Vector control

3.      High speed drive

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, to apply the vector control to the SRM in the high speed drive, the 20-pole 30-slot SRM driven in 20000rpm which has same electrical angular frequency for the 8-pole 12- slot SRM driven in 50000rpm was designed and evaluated. As a result of analysis, the proposed motor satisfied the demand performances such as torque and output power in the vector control by using the SiC inverter which has the switching frequency 200kHz. In the experiment, it was clarified that the proposed SRM can be driven by the vector control at the maximum rotation speed 20000rpm. That is, it means that the 8-pole 12-slot SRM can be driven in 50000rpm by the vector control. Finally, it was shown that the vibration of SRM can be reduced in the high speed region by applying the vector control compared with that in the conventional single pulse drive.

REFERENCES:

[1] M. Besharati, J. Widmer, G. Atkinson, V. Pickert, Jamie Washington : “Super-high-speed switched reluctance motor for automotive traction”, in Proc. of IEEE Energy Conversion Congress and Exposition (ECCE), pp.5241-5248, Sept. 2015.

[2] Earl W. Fairall, Berker Bilgin, Ali Emadi : “State-of-the-Art High-speed Switched Reluctance Machines”, IEEE International Electric Machines and Drives Conference (IEMDC), pp.1621- 1627, May 2015.

[3] A. Chiba, K. Kiyota, N. Hoshi, M. Takemoto, S. Ogasawara, “Development of a Rare-Earth-Free SR Motor with High Torque Density for Hybrid Vehicles”, IEEE Transactions on Energy Conversion, vol.30, no.1, pp.175-182, Mar. 2015.

[4] K. Ueta, K. Akatsu, “Study of high-speed SRM with amorphous steel sheet for EV”, in Proc. of 19th International Conference on Electrical Machines and Systems 2016 (ICEMS 2016), Feb. 2017.

[5] S. P. Nikam, V. Rallabandi, B. G. Fernandes, “A High-Torque- Density Permanent-Magnet Free Motor for in-Wheel Electric Vehicle Application” IEEE Transaction on Industry Application, vol. 48, no. 6, pp.2287-2295, Nov. 2012.

Design and Implementation of MultilevelInverters for Electric Vehicles

ABSTRACT:

The efficient and compact design of multilevel inverters (MLI) motivates in various applications such as solar PV and electric vehicles (EV). This paper proposes a 53-Level multilevel inverter topology based on a switched capacitor (SC) approach. The number of levels of MLI is designed based on the cascade connection of the number of SC cells. The SC cells are cascaded for implementing 17 and 33 levels of the output voltage. The proposed structure is straightforward and easy to implement for the higher levels. As the number of active switches is less, the driver circuits are reduced. This reduces the device count, cost, and size of the MLI. The solar panels, along with a perturb and observe (P&O) algorithm, provide a stable DC voltage and is boosted over the DC link voltage using a single input and multi-output converter (SIMO). The proposed inverters are tested experimentally under dynamic load variations with sudden load disturbances. This represents an electric vehicle moving on various road conditions. A detailed comparison is made in terms of switches count, gate driver boards, sources count, the number of diodes and capacitor count, and component count factor. For the 17-level, 33-level, and 53-level MLI, simulation results are verified with experimental results, and total harmonic distortion (THD) is observed to be the same and is lower than 5% which is under IEEE standards. A hardware prototype is implemented in the laboratory and verified experimentally under dynamic load variations, whereas the simulations are done in MATLAB/Simulink.

KEYWORDS:                                                                   

1.      Cascaded H-bridge inverter

2.      Sinusoidal pulse-width modulation

3.      Total harmonic distortion

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The proposed switched-capacitor based 53-level MLI topology for electric vehicle applications is designed and implemented for the solar PV energy system with lesser semiconductor devices to reduce the cost and size of the inverter, improving efficiency and reliability. P&O algorithm based MPPT technique is used, the stable output is achieved under all circumstances. The proposed MLI is implemented with various combinations of SC connections. A basic two units are cascaded and obtained a 17-level MLI configuration. The cascade connection of two 17-level MLIs results in the formation of a 33-level MLI, and the proposed 53-level MLI is achieved by cascading three SC units. All the MLIs are designed and compared with various topologies based on several parameters like devices count, TSV, THD, and cost function per level count. The comparative analysis shows that the proposed MLI is more efficient with fewer power losses. It is noticed that both simulation and experimental THD are 1.41%. TSVpu is 1.15; efficiency is 94.21%, CF/L values for both values of α are 0.7 and 0.73, which clearly shows the cost is significantly less compared with various topologies. The proposed MLI is tested under multiple dynamic load variations. This topology is most suited for renewable energy applications.

REFERENCES:

[1] J. Rodriguez, J.-S. Lai, and F. Z. Peng, ``Multilevel inverters: A survey of topologies, controls, and applications,'' IEEE Trans. Ind. Electron., vol. 49, no. 4, pp. 724_738, Aug. 2002.

[2] L. Franquelo, J. Rodriguez, J. Leon, S. Kouro, R. Portillo, and M. Prats,

``The age of multilevel converters arrives,'' IEEE Ind. Electron. Mag., vol. 2, no. 2, pp. 28_39, Jun. 2008.

[3] K. K. Gupta and S. Jain, ``A novel multilevel inverter based on switched DC sources,'' IEEE Trans. Ind. Electron., vol. 61, no. 7, pp. 3269_3278, Jul. 2014.

[4] L. Zhang, K. Sun, Y. Xing, and J. Zhao, ``A family of five-level dual- buck full-bridge inverters for grid-tied applications,'' IEEE Trans. Power Electron., vol. 31, no. 10, pp. 7029_7042, Oct. 2016.

[5] R. Agrawal and S. Jain, ``Comparison of reduced part count multilevel inverters (RPC-MLIs) for integration to the grid,'' Int. J. Electr. Power Energy Syst., vol. 84, pp. 214_224, Jan. 2017.

A Single-Carrier-Based Pulse-Width Modulation Template for Cascaded H-Bridge Multilevel Inverters

 ABSTRACT:

 Multiplicity of the triangular carrier signals is a criterion for the extension of sinusoidal pulsewidth modulation, SPWM, to a number of output voltage levels per phase-leg in cascaded H-bridge (CHB) multilevel inverter (MLI). Considering medium and high voltage applications where appreciable number of output voltage levels from CHB MLI is needed, commensurate high number of carrier signals in either classical level- or phase-shifted SPWM scheme for this inverter is inevitable. High-quality output waveforms from CHB MLI system demands precise synchronization of these multi-carrier signals. Sampling issues, memory constraints and computational delays pose difficulties in achieving this synchronization for real-time digital implementation. This study presents a PWM template for CHB MLI. The developed control concept generates adequate modulation templates for CHB inverter wherein a sinusoidal modulating waveform is modified to fit in a single triangular carrier signal range. These templates can be used on CHB inverter of any level with no further control modification. Nearly even distribution of switching pulses, equal sharing of the overall real power among the constituting power switches and enhanced output voltage quality were achieved with the proposed modulation. For a 3-phase, 7-level CHB, simulation and experimental results, for an R-L load, were presented

KEYWORDS:

1.      Cascaded H-bridge inverter

2.      Sinusoidal pulse-width modulation

3.      Total harmonic distortion

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

Presented in this paper is a hybridized single carrier-based pulse width modulation scheme for cascaded H-bridge multilevel inverter. Its operational concept wherein a sinusoidal modulating waveform is modified to fit in a single triangular carrier signal range in order to generate the desired output waveform template for the MLI has been explained in detail. The principle of generating the modulating templates is a furtherance of earlier established modulation approaches for multilevel inverters. It has been shown that the generation of the modulating templates is a clear demonstration of the extension of the well-known bipolar PWM to multi-cascaded H-bridge units. Once the templates are generated, it can be used on CHB inverter of any level with no further control modification; only the parameter N need to be specified. From industrial point of view, the presented concept of MWT will find its application in large number of cascaded H-bridge systems because with the proposed modulation, the inverter control system becomes insensitive to the traditional concept of multiplicity of carrier waves as the number of inverter level increases. This will be highly advantageous since the extra control effort of carrier synchronization will be by-passed in the control algorithm. The proposed SPWM ensures nearly even distribution of switching pulses among the constituting power switches using a reverse-voltage-sorting comparison algorithm. Consequently, the real power variations in the entire cascaded H-bridges are kept within a very narrow band. From our findings, the proposed control approach results in a hybrid modulation scheme that mediates between the phaseand level-shifted carrier-based SPWM techniques; thereby inheriting the good features in these two modulation schemes. The performance of the proposed SPWM scheme has been presented through scaled down simulations and experiments on a 3-phase, 7-level CHB inverter; results have been adequately presented.

REFERENCES:

[1] S. K. Chattopadhyay and C. Chakraborty, ‘‘Full-bridge converter with naturally balanced modular cascaded H-bridge waveshapers for offshore HVDC transmission,’’ IEEE Trans. Sustain. Energy, vol. 11, no. 1, pp. 271–281, Jan. 2020, doi: 10.1109/TSTE.2018.2890575.

 [2] X. Zeng, D. Gong, M. Wei, and J. Xie, ‘‘Research on novel hybrid multilevel inverter with cascaded H-bridges at alternating current side for highvoltage direct current transmission,’’ IET Power Electron., vol. 11, no. 12, pp. 1914–1925, Oct. 2018, doi: 10.1049/iet-pel.2017.0925. [3] R. K. Varma and E. M. Siavashi, ‘‘PV-STATCOM: A new smart inverter for voltage control in distribution systems,’’ IEEE Trans. Sustain. Energ., vol. 9, no. 4, pp. 1681–1691, Oct. 2018, doi: 10.1109/ TSTE.2018.2808601.

[4] P. Sotoodeh and R. D. Miller, ‘‘Design and implementation of an 11- level inverter with FACTS capability for distributed energy systems,’’ IEEE J. Emerg. Sel. Topics Power Electron., vol. 2, no. 1, pp. 87–96, Mar. 2014, doi: 10.1109/JESTPE.2013.2293311.

[5] A. Ahmed, M. S. Manoharan, and J.-H. Park, ‘‘An efficient single-sourced asymmetrical cascaded multilevel inverter with reduced leakage current suitable for single-stage PV systems,’’ IEEE Trans. Energy Convers., vol. 34, no. 1, pp. 211–220, Mar. 2019, doi: 10.1109/TEC.2018.2874076.

Bidirectional Conductive Charging of Electric Vehicles for V2V Energy Exchange

ABSTRACT:

 Battery-powered Electric Vehicles (EVs) are considered as an effective solution to curb carbon emissions and fight global warming. One of the main drawbacks in driving an EV is range anxiety, which can be defined as the fear of vehicle having insufficient range to reach its destination due to lack of charging. Vehicle-to-vehicle (V2V) charging is being explored as a solution to mitigate the range anxiety issue. V2V charging allows the sharing of charge between two EVs so that if an EV is stranded far from a charging station, it can be charged from another EV. Various V2V chargers have been studied. It has been found that the traditional chargers involve many power conversion stages, which reduces the efficiency in the energy exchange. In this paper, an off-board DC V2V charger is presented. It reduces the power conversion stages while dispensing with the use of any on-board charger. To implement the off-board DC V2V charger, a bidirectional DC-DC converter is adopted. The converter operates in various modes, depending upon voltage and state of charge of the EV batteries. In turn, the V2V charging is managed in an automatic way. Operation modes and management program of the off-board V2V charger are discussed in the paper.

KEYWORDS:

1.      V2V charging

2.      Battery SOC

3.      Bidirectional buck boost converter

 SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

The V2V conductive charging is a viable way to share charge between the batteries of two EVs; it can be used when an EV is stranded due to lack of charging and it did not stop at a charging station. The efficiency of the traditional V2V chargers is poor due to the presence of many power conversion stages. To overcome such an issue, this paper has explored an off-board DC V2V charger that utilizes only one DC-DC power conversion stage constituted by a BBB converter. The charger has been examined thoroughly, illustrating the six different modes of operation and addressing the V2V charging management. Throughout the paper, a BBB converter is sized, and simulations of its operation are carried out on a MATLAB Simulink platform. It is expected that hardware implementation of the BBB converter and its control system together with their testing in a practical environment can validate effectiveness and benefits of off-board DC V2V charging.

REFERENCES:

[1] C. C. Chan, "The State of the Art of Electric, Hybrid, and Fuel Cell Vehicles," in Proceedings of the IEEE, vol. 95, no. 4, pp. 704-718, April 2007.

[2] E. Bulut and M. C. Kisacikoglu, "Mitigating Range Anxiety via Vehicleto- Vehicle Social Charging System," 2017 IEEE 85th Vehicular Technology Conference (VTC Spring), Sydney, NSW, 2017, pp. 1-5.

[3] T. J. C. Sousa, V. Monteiro, J. C. A. Fernandes, C. Couto, A. A. N. Meléndez and J. L. Afonso, "New Perspectives for Vehicle-to-Vehicle (V2V) Power Transfer," IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society, Washington, DC, 2018, pp. 5183- 5188.

[4] S. K. Vempalli, K. Deepa and Prabhakar.G, "A Novel V2V Charging Method Addressing the Last Mile Connectivity," 2018 IEEE International Conference on Power Electronics, Drives and Energy Systems (PEDES), Chennai, India, 2018, pp. 1-6.

[5] H. Lee and J. Yun, "High-Efficiency Bidirectional Buck–Boost Converter for Photovoltaic and Energy Storage Systems in a Smart Grid," in IEEE Transactions on Power Electronics, vol. 34, no. 5, pp. 4316-4328, May 2019, doi: 10.1109/TPEL.2018.2860059.

Power Quality Improvement in Solar Fed Cascaded Multilevel Inverter with Output Voltage Regulation Techniques

ABSTRACT:

The presence of harmonics in solar Photo Voltaic (PV) energy conversion system results in deterioration of power quality. To address such issue, this paper aims to investigate the elimination of harmonics in a solar fed cascaded fifteen level inverter with aid of Proportional Integral (PI), Artificial Neural Network (ANN) and Fuzzy Logic (FL) based controllers. Unlike other techniques, the proposed FLC based approach helps in obtaining reduced harmonic distortions that intend to an enhancement in power quality. In addition to the power quality improvement, this paper also proposed to provide output voltage regulation in terms of maintaining voltage and frequency at the inverter output end in compatible with the grid connection requirements. The simulations are performed in the MATLAB / Simulink environment for solar fed cascaded 15 level inverter incorporating PI, ANN and FL based controllers. To exhibit the proposed technique, a 3 kWp photovoltaic plant coupled to multilevel inverter is designed and hardware is demonstrated. All the three techniques are experimentally investigated with the measurement of   power quality metrics along with establishing output voltage regulation.

KEYWORDS:

1.      Harmonics

2.      Intelligent Control

3.      Multilevel Inverter

4.      Photo Voltaic’s

5.      Power Quality

6.      Voltage Regulation

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The voltage regulation topology along with power quality improvement is considered and implemented both in simulation and experimental setup for a solar fed 15 level inverter. While considering the results, it is found that FLC presents better results for VR while considering the variations at the input solar PV. Despite this, FLC is considered for the nine-level by [23], but the implementation is carried out with the DC power supplies without utilizing the solar panels. All the other methods are implemented for low power and lesser levels of MLI topology. Commercial utilization of MLI by providing the constant output voltage is investigated, and the experimental results prove the effectiveness of the proposed system. The method is applicable for the users require grid interaction along with the power quality improvement.

REFERENCES:

[1]. S. Karekezi, T. Ranja, T., “Renewable technologies in Africa”, London: Zed Books, 1997.

[2]. S. Karekezi, W. Kithyoma, “Renewable energy strategies for rural Africa: is a PV-led renewable energy strategy the right approaches for providing modern energy to the rural poor of sub-Saharan Africa”, Energy Policy, vol. 30, pp. 1071-1086, Sep. 2002.

[3]. S. Karekezi, W. Kithyoma, “Renewable energy in Africa: prospects and limits in Renewable energy development, The Workshop for African Energy Experts on Operationalizing the NEPAD energy Initiative”, vol. 1, pp. 1-30, 2-4 Jun. 2003. (Dakar, Senegal;: NEPAD Initiatives, In Collaboration with United Nations and Republic of Senegal. Retrieved 06 18, 2017, From https://sustainabledevelopment.un.org/content/documents/nepa dkarekezi.pdf)

[4]. T. Djiby-Racine, “Renewable decentralized in developing countries: appraisal from microgrids project in Senegal,” S. Direct, Ed., Renewable Energy, vol. 35, no. 8, pp. 1615-1623, Aug. 2010.

[5]. F. Christoph, “World Energy Scenarios: Composing energy futures to 2050,” World Energy Council. London, United Kingdom: World Energy Council, 2013.

A Generalized Multilevel Inverter Topology with Reduction of Total Standing Voltage

ABSTRACT:

This paper presents a new multilevel inverter topology with reduced active switches and total standing voltage. The proposed topology can generate a high number of voltage levels in the symmetric configuration. This topology intuitively generates positive and negative cycles without an additional H-bridge unit, which considerably reduces the total standing voltage of the inverter. A cascaded structure is developed from the proposed topology to create higher voltage levels. To show the novelty of the proposed topology, a thorough comparison between the available and the proposed topologies in terms of the number of switches, standing voltages, and dc-sources is presented. Furthermore, he power loss analysis is carried out for various load values. The feasibility of the proposed nine-level inverter is verified with simulation and experimental results.

KEYWORDS:

1.      Multilevel inverter

2.      Inverter

3.      Blocking voltage

4.      Cascaded structure

5.      Reduced power components

 SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

The proposed topology used lower number of power electronics components and reduced dc-sources. Further, the maximum voltage stress on the switch is reduced to 4Vdc for any number of voltage levels in symmetric configuration which is more suitable for medium voltage applications. The simulated and experimental results are presented for various load values. The sudden load changes and modulation index variations are applied to the proposed topology and it corresponding results are given. Further, the power loss and efficiency of propose topology presented for various load power. It is confirming that the proposed topology is more suitable various load changing applications like AC drives, grid connected PV system etc.

REFERENCES:

[1] S. A. Teston, M. Mezaroba, and C. Rech, “Anpc inverter with integrated secondary bidirectional dc port for ess connection,” IEEE Transactions on Industry Applications, vol. 55, no. 6, pp. 7358–7367, 2019.

[2] Jing Huang and K. A. Corzine, “Extended operation of flying capacitor multilevel inverters,” IEEE Transactions on Power Electronics, vol. 21, no. 1, pp. 140–147, 2006.

[3] S. P. Gautam, “Novel h-bridge-based topology of multilevel inverter with reduced number of devices,” IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 7, no. 4, pp. 2323–2332, 2019.

[4] S. A. A. Ibrahim, A. Palanimuthu, and M. A. J. Sathik, “Symmetric switched diode multilevel inverter structure with minimised switch count,” The Journal of Engineering, vol. 2017, no. 8, pp. 469–478, 2017.

[5] S. S. Lee, M. Sidorov, N. R. N. Idris, and Y. E. Heng, “A symmetrical cascaded compact-module multilevel inverter (ccm-mli) with pulsewidth modulation,” IEEE Transactions on Industrial Electronics, vol. 65, no. 6, pp. 4631–4639, 2018.