A PWM Strategy Based on State Transition for Cascaded H-Bridge Inverter under Unbalanced DC Sources

ABSTRACT:  

 

 Cascaded H-bridge converter has been widely used and researched in industry, since it is suitable for the operation under both normal and fault conditions. This paper proposes a novel PWM strategy based on state transition for cascaded H-Bridge inverter with unbalanced DC sources to achieve high quality line-to-line output voltages and maximize the linear modulation range. In this modulation strategy, the duration time of each switching state will be modified directly through the correction value. Ranges of correction value are derived by analyzing the modulation index limitation. Then, proper correction value is added into duration times to transform the switching states and extend modulation index to the maximum value. Meanwhile, balanced AC currents can be obtained under unbalanced DC sources condition, even under larger unbalanced coefficients. Furthermore, a three-phase power control algorithm (PCA) is introduced to achieve the balanced distribution of three-phase power. Compared with the traditional zero-sequence voltage injection method, the proposed strategy is more convenient and effective theoretically, and it can be applied to the higher-level cascaded H-bridge converter. The advantage and effectiveness of the proposed strategy are verified by simulation and experiment results.

KEYWORDS:

 

1.      State transition

2.      Linear modulation range

3.      Unbalanced DC sources

4.      Power control algorithm

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

A novel PWM strategy based on state transition for CHBI with unbalanced DC sources has been proposed in this paper. Compared with ZSVIM and NVM, the duration times of each switch states can be modified directly by correction value and the gate signals can be acquired easily through ST-PWM. To acquire the maximum linear modulation index, the reason of the modulation index limitation and the novel modulation strategy based on the state transition are studied. The proposed strategy can achieve high quality line-to-line output voltages and extend the modulation range as high as possible. Besides, the three-phase power control algorithm is introduced to acquire balanced power distribution. The effectiveness has been verified by simulation and experiment results.

In our current work, we incorporate PCA into the ST-PWM strategy, which is a prototype of multi-objective control. Since both modulation index extension and power control are achieved by adjusting ΔT, there is a conflict on the control objectives. That is to say, the control ability of PCA will decrease when the modulation index is extended. However, we have not yet found a strict mathematical relationship between them due to time constraints. And we will do a further research on multi-objective optimal PWM strategy and multi-objective control boundaries under unbalanced dc sources in the future.

REFERENCES:

[1] A. Marzoughi, R. Burgos, D. Boroyevich, and Y. Xue, "Investigation and comparison of cascaded H-bridge and modular multilevel converter topologies for medium-voltage drive application," in Industrial Electronics Society, IECON 2014 - 40th Annual Conference of the IEEE, 2014, pp. 1562-1568.

[2] 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, Aug. 2010.

[3] X. Zha, L. Xiong, J. Gong and F. Liu, "Cascaded multilevel converter for medium-voltage motor drive capable of regenerating with part of cells," IET Power Electronics, vol. 7, no. 5, pp. 1313-1320, May. 2014.

[4] G. Farivar, C. D. Townsend, B. Hredzak, J. Pou, and V. G. Agelidis, "Low-capacitance cascaded H-bridge multilevel StatCom," IEEE Trans. Power Electron., vol. 32, no. 3, pp. 744-1754, Mar. 2017.

[5] K. D. Teryima, G. Y. Nentawe, and A. O. David, "A Overlapping Carrier Based SPWM for a 5-Level Cascaded H-bridge Multilevel Inverter," International Journal of Power Electronics and Drive Systems (IJPEDS), vol. 7, no. 2, pp. 349-357, 2016.

A Physical Deterministic Inverse Method for Operational Satellite Remote Sensing: An Application for Sea Surface Temperature Retrievals

 ABSTRACT:  

We propose a new deterministic approach for remote sensing retrieval, called modified total least squares (MTLS), built upon the total least squares (TLS) technique. MTLS implicitly determines the optimal regularization strength to be applied to the normal equation first-order Newtonian retrieval using all of the noise terms embedded in the residual vector. The TLS technique does not include any constraint to prevent noise enhancement in the state space parameters from the existing noise in measurement space for an inversion with an ill-conditioned Jacobian. To stabilize the noise propagation into parameter space, we introduce an additional empirically derived regularization proportional to the logarithm of the condition number of the Jacobian and inversely proportional to the L2-norm of the residual vector. The derivation, operational advantages and use of the MTLS method are demonstrated by retrieving sea surface temperature from GOES-13 satellite measurements. An analytic equation is derived for the total retrieval error, and is shown to agree well with the observed error. This can also serve as a quality indicator for pixel-level retrievals. We also introduce additional tests from the MTLS solutions to identify contaminated pixels due to residual clouds, error in the water vapor profile and aerosols. Comparison of the performances of our new and other methods, namely, optimal estimation and regression-based retrieval, is performed to understand the relative prospects and problems associated with these methods. This was done using operational match-ups for 42 months of data, and demonstrates a relatively superior temporally consistent performance of the MTLS technique.

KEYWORDS:

1.      Condition number of matrix

2.      Ill-conditioned inverse methods

3.      Regularization

4.      Satellite remote sensing

5.      Sea surface temperature (SST)

6.      Total error

7.      Total least squares (TLS)

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

We have demonstrated in this work the advantage of the MTLS, which is the family of the deterministic inverse methods, for producing SST retrievals compared with other prevailing methods. In addition, it is noteworthy that MTLS does not require additional error information, e.g., well-specified errors in observational and a priori information. This may provide a significant advantage for climate-based applications where retrievals should be as independent of external error sources as possible. The MTLS retrieval is improved by using the newer version of CRTM, which implies that more accurate forward models and ancillary data can further reduce the remaining MTLS error. This package can also calculate a metric relating to the total retrieval error and automatic QI at individual pixel level. Apart from the QI, MTLS is also capable of identifying the most difficult retrievals due to cloud contamination or high WV profile error. The sensitivity analysis confirms that MTLS solution is independent of a priori/IG error. The data driven dynamic regularization property of MTLS regularizes solutions toward the IG when the problem is either highly ill-conditioned or has high observation error or both to keep the solution below the a priori error. It is found that OEM retrieval, at least as implemented for this problem, is worse than the LS solution, and sometimes worse than the a priori error, irrespective of the version of CRTM. OEM is the most popular choice for physically based operational retrievals due to the assumption that a priori based constraining of an ill-posed inversion should still yield reasonable reasonable results under conditions where there may be unaccounted for parameters or unforeseen errors, as may be the case in real-world retrieval problems. However, these results suggest that this view may be based more on perception of idealized Bayesian statistics rather than comparative scientific study with respect to alternative methods. This study has also demonstrated that the sensitivity of OEM retrievals under practical circumstances renders it more vulnerable to noise than MTLS retrievals. Even by employing dynamic error covariance matrices, OEM is unable to produce the best retrieval for a fairly linear and moderately ill-conditioned problem of SST retrieval. Moreover, the estimation of error of the errors, which is a prerequisite for OEM, is rather difficult in practice, which perhaps explains why OEM results do not match the expectation from the theory of adding to/constraining by a priori knowledge. To date, operational SST retrievals are dominated by regression (REGB), which highly simplifies RT physics. Mostly, it does produce reasonable results (SD) due to the fact that the global variance of SST fields itself is not very high (e.g., compared with gaseous distributions) and the atmospheric attenuation for 3.9-μm channel is rather low, but such methods are still subject to biases on a spatial and temporal basis, with seasonal variations, and has no inherent means of correcting for them. This derivation of MTLS is based on linear algebra. However, this paper illustrates that a deterministic classical mathematics approach can produce better retrievals for real-world RT problems compared with more recent probability-based mathematics that solve ill-posed problems using covariance matrices. The MTLS retrievals outperform the OEM retrievals due to the fact that the regularization in MTLS is data driven. As opposed to OEM that uses regularization from user-defined a priori knowledge of measurement error and forward model error, as well as a priori knowledge error of the retrieved target parameter. A reliable estimation of both the errors in an operational environment is very difficult due to the highly dynamic atmosphere, fast forward model error, including NCEP data, as well as error in the measurements. An alternate effort toward error estimation using simulation minus observation (S-O) bias correction leads to further ambiguities and may potentially mislead our fundamental science understanding. With the advent of newer sensors with improved multispectral capabilities (e.g., the Visible and Infrared Imaging Radiometer Suite and the future Advanced Baseline Imager), employing a deterministic physical method for simultaneous retrieval of SST and WV (critical for weather and climate studies), such as the MTLS package, has the potential to provide substantial improvements in the use of satellite data and derived products.

REFERENCES:

[1] P. Le Borgne, H. Roquet, and C. J. Merchant, “Estimation of sea surface temperature from the spinning enhanced visible and infrared imager, improved using numerical weather prediction,” Remote Sens. Environ., vol. 115, no. 1, pp. 55–65, Jan. 2011.

[2] C. D. Rodgers, Inverse Methods for Atmospheric Soundings: Theory and Practice. Singapore: World Scientific, 2000.

[3] S. Twomey, An Introduction to the Mathematics of Inversion in Remote Sensing and Indirect Measurements. New York, NY, USA: Elsevier, 1977.

[4] J. T. Houghton, F. W. Taylor, and C. D. Rodgers, Remote Sounding of Atmospheres. Cambridge, U.K.: Cambridge Univ. Press, 1984.

[5] J. L. Mead, “Parameter estimation: A new approach to weighting a priori information,” J. Inv. Ill-Posed Probl., vol. 16, no. 2, pp. 1–21, 2007.

A Multi-Cell 21-Level Hybrid Multilevel Inverter synthesizes a reduced number of components with Voltage Boosting Property

ABSTRACT:  

 

 A multi-cell hybrid 21-Level multilevel inverter is proposed in this paper. The proposed topology includes two-unit; an H-bridge is cascaded with a modified K-type unit to generate an output voltage waveform with 21 levels based only on two unequal DC suppliers. The proposed topology's advantage lies in the fine and clear output voltage waveforms with high output efficiency. Meanwhile, the high number of output voltage waveform levels generates a low level of distortion and reduces the level of an electromagnetic interface (EMI). Moreover, it reduces the voltage stress on the switching devices and gives it a long lifetime. Also, the reduction in the number of components has a noticeable role in saving size and cost. Regarding the capacitors charging, the proposed topology presents an online method for charging and balancing the capacitor's voltage without any auxiliary circuits. The proposed topology can upgrade to a high number of output steps through the cascading connection. Undoubtedly this cascading will increase the power level to medium and high levels and reduce the harmonics content to a neglectable rate. The proposed system has been tested through the simulation results, and an experimental prototype based on the controller dSPACE (DS-1103) hardware unit used to support the simulation results.

KEYWORDS:

 

1.      21-Level Multilevel Inverter (MLI)

2.      Hybridization

3.      Modified K-type inverter

4.      Online charging

5.      Self-balancing

6.      Voltage boosting inverter

7.      Total Harmonic Distortion (THD)

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

The work in this paper presented a hybrid multilevel inverter that consisted of a series connection between two units (an HB unit with a modified K-Type unit). This combination generates an output voltage waveform with 21 steps. This high number steps in the output voltage help in reducing the level of noises in the output voltage and reduced the stress in the switching devices, which on the one hand generating fine and clear waveforms and on the other hand reduces the harmonic content in the waveforms to a deficient level (satisfying the harmonics standard IEEE519). Economically, the structure of the proposed topology presented an optimal design in terms of reducing the number of switches and DC sources which in turn enhancing the system reliability by reducing the inverter cost. For the capacitors charging process, the paper presents an online method for charging and balancing the capacitor voltages without any auxiliary circuits for that. This helps in the continuous operation of the charging and discharging process for the capacitor without disturbing the process of generating the output voltage. The proposed topology supports the modularity process in order to maximize the range of output power to the medium and high level, and the paper presented two scenarios for the series connection 2HB+K and HB+2K both the cases raise the level of the output power and enhances the system performance to achieve high efficiency. Due to the dependence on multi DC sources, this topology is suitable for renewable energy applications; DC sources are abundant. The hybrid renewable energy sources application will be more appropriate between all the renewable energy applications because the proposed topology-based mainly on two unequal DC suppliers, which will be available easily in the hybrid renewable energy sources.

REFERENCES:

[1] F. Z. Peng, W. Qian, and D. Cao, "Recent advances in multilevel converter/inverter topologies and applications," in The 2010 International Power Electronics Conference-ECCE ASIA-, 2010, pp. 492-501.

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

[3] L. M. Tolbert and X. Shi, "Multilevel power converters," in Power Electronics Handbook, ed: Elsevier, 2018, pp. 385-416.

[4] K. K. Gupta, A. Ranjan, P. Bhatnagar, L. K. Sahu, and S. Jain, "Multilevel inverter topologies with reduced device count: A review," IEEE transactions on power electronics, vol. 31, pp. 135-151, 2015.

[5] P. Omer, J. Kumar, and B. S. Surjan, "A Review on Reduced Switch Count Multilevel Inverter Topologies," IEEE Access, vol. 8, pp. 22281-22302, 2020.

A Modified Carrier-Based Advanced Modulation Technique For Improved Switching Performance of Magnetic Linked Medium Voltage Converters

ABSTRACT:  

The high-frequency magnetic link is gaining popularity due to its light weight, small volume, and inherent voltage balancing capability. Those features can simplify the utilization of multilevel converter (MLC) for the integration of renewable energy sources to the grid with compact size and exert economic feasibility. The modulation and control of MLC are crucial issues especially for grid connected applications. To support the grid, the converter may need to operate in over-modulation (OVM) region for short periods depending upon the loading conditions. This OVM operation of the converter causes increased harmonic losses and adverse effects on overall system efficiency. On top of that, the size and cost of filtering circuitry become critical to eliminate the unwanted harmonics. In this regard, a modified OVM scheme with phase disposed carriers for grid connected high frequency magnetic link-based cascaded H-bridge (CHB) MLC is proposed for the suppression of harmonics and the reduction of converter loss. Furthermore, with the proposed OVM technique, the voltage gain with modulation index can be increased up to the range which is unlikely to be achieved using the classical ones. Extensive simulations are carried out with a 2.24 MVA permanent magnet synchronous generator-based wind energy conversion system which is connected to the 11 kV ac grid through a high-frequency magnetic link and a 5-level CHB MLC. A scaled down laboratory prototype is implemented to validate the performance of the converter.

KEYWORDS:

1.      Multilevel converter

2.      Over modulation

3.      Grid connection

4.      High-frequency magnetic link

5.      Wind energy

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

To improve the system performance, a modified OVM technique is presented in this paper with grid connected and islanded operation. With the proposed modified carrier signal based BCPWM techniques, the overall loss and THD are decreased for both the islanded and grid connected modes compared with the traditional OVM techniques. Moreover, the voltage gain can be increased and remains approximately constant in the proposed method, which may not be possible to obtain using the traditional OVM methods. In this paper, a high-frequency magnetic link-based fully-rated CHB converter is developed for wind energy applications and the behavior of the system under rated and overrated load conditions are investigated.The use of magnetic link for the generation of isolated and balanced dc sources of the MLC inherently overcomes the voltage imbalance problem of CHB MLC and hence effectively simplifies the system control complexities. The core loss of high-frequency magnetic link is also measured to identify the overall loss of the system. The effectiveness of the proposed technology is confirmed by the simulation and experimental results.

REFERENCES:

 

[1] M. R. Islam, Y. G. Guo, J. G. Zhu, H. Lu, and J. X. Jin, “High-frequency magnetic-link medium-voltage converter for superconducting generator-based high-power density wind generation systems,” IEEE Trans. Appl. Supercond., vol. 24, no. 5, pp. 1–5, Oct. 2014.

[2] N. Mendis, K. M. Muttaqi, S. Perera, and S. Kamalasadan, “An effective power management strategy for a wind–diesel–hydrogen-based remote area power Supply System to meet fluctuating demands under generation uncertainty,” IEEE Trans. Ind. Appl., vol. 51, no. 2, pp. 1228–1238, Mar.–Apr. 2015.

[3] B. Jain, S. Jain, and R. K. Nema, “Control strategies of grid interfaced wind energy conversion system: An overview,” Renew. Sustain. Energy Rev., vol. 47, pp. 983–996, Apr. 2015.

[4] Y. Tan, K. M. Muttaqi, P. Ciufo, and L. Meegahapola, “Enhanced frequency response strategy for a PMSG-based wind energy conversion system using ultracapacitor in remote area power supply systems,” IEEE Trans. Ind. Appl., vol. 53, no. 1, pp. 549–558, Jan.–Feb. 2017.

[5] M. R. Islam, Y. G. Guo, and J. G. Zhu, “A multilevel medium-voltage inverter for step-up-transformer-less grid connection of photovoltaic power plants,” IEEE J. Photovolt., vol. 4, no. 3, pp. 881‒889, May 2014.

 

A Dual Control Strategy for Power Sharing Improvement In Islanded Mode of AC Microgrid

 ABSTRACT:  

Parallel operation of inverter modules is the solution to increase the reliability, efficiency, and redundancy of inverters in microgrids. Load sharing among inverters in distributed generators (DGs) is a key issue. This study investigates the feasibility of power-sharing among parallel DGs using a dual control strategy in islanded mode of a microgrid. PQ control and droop control techniques are established to control the microgrid operation. P-f and Q-E droop control is used to attain real and reactive power sharing. The frequency variation caused by load change is an issue in droop control strategy whereas the tracking error of inverter power in PQ control is also a challenge. To address these issues, two DGs are interfaced with two parallel inverters in an islanded AC microgrid. PQ control is investigated for controlling the output real and reactive power of the DGs by assigning their references. The inverter under enhanced droop control implements power reallocation to restore the frequency among the distributed generators with predefined droop characteristics. A dual control strategy is proposed for the AC microgrid under islanded operation without communication link. Simulation studies are carried out using MATLAB/SIMULINK and the results show the validity and effective power-sharing performance of the system while maintaining a stable operation when the microgrid is in islanding mode.

KEYWORDS:

1.      Microgrid

2.      Inverter parallel operation control strategy

3.      Droop control strategy

4.      Frequency restore

5.      Power sharing

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, the enhanced droop and PQ control strategies for controlling parallel DGs in islanding mode of AC micro-grids were investigated to achieve flexible power regulation. The main advantage of this dual control strategy is to enable operation without any communication between the parallel DGs. The power tracking error for PQ control based inverters was investigated and the enhanced droop control implemented with predefined droop characteristics for power reallocation was proposed. To improve and restore the frequency, a frequency restoration scheme (FRS) implemented among the distributed generators was developed. The proposed droop controller provides stable operating under different control strategies in islanded operation and the DG voltage can quickly respond to the required voltage demand. The PQ controller can effectively track the active and reactive power and the droop control provides voltage control in islanded mode. The simulation results obtained from MATLAB/SIMULINK verified the stability of the load voltage and frequency.

REFERENCES:

1. Parhizi, S., et al. (2015). State of the art in research on micro-grids: A review. IEEE Access, 3, 890–925.

2. Lopes, J. A. P., Moreira, C. L., & Madureira, A. G. (2006). Defining control strategies for micro-grids islanded operation. IEEE Transactions on Power Apparatus and Systems, 21(2), 916–924.

3. Ahmed, M. N., et al. (2015). An overview on microgrid control strategies. International Journal of Engineering and Advanced Technology (IJEAT), 4(5), 93–98.

4. Lasseter, R. H. (2002). Micro-grids. In 2002 IEEE Power Engineering Society Winter Meeting. Conference Proceedings (Cat. No.02CH37309) (Vol. 1, pp. 305–308).

5. Basak, P., Saha, A. K., Chowdhury, S., & Chowdhury, S. P. (2009). Micro-grid: Control techniques and modeling. 44th International Universities Power Engineering Conference (UPEC), Glasgow IEEE. (pp. 1–5).

Modified Cascaded H-bridge Multilevel Inverter for Hybrid Renewable Energy Applications

 ABSTRACT:

Renewable energy sources and technologies have the potential to provide solutions to the longstanding energy problems being faced by developing countries. The renewable energy sources like wind energy, solar energy, geothermal energy, ocean energy, biomass energy and fuel cell technology can be used to overcome energy shortage in India. This paper proposes a modified multi-level inverter (MLI) topology for Hybrid Renewable Energy Sources (HRES) and a design of hybrid solar-wind power generation model with 9-level, 13-level and 17-level inverter topologies. A HRES connected to a modified Cascaded H-Bridge Multi Level Inverter (CHB-MLI) is developed, whose switches are controlled using Artificial Neural Network (ANN) model. The proposed hybrid energy system model consists of 10 Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) that intend to give 17 levels of output voltage. The proposed topology performs effectively with reduced number of components and reduced Total Harmonic Distortion (THD). The performance of the proposed system is analyzed by designing the model in MATLAB/SIMULINK environment. The simulation results of the proposed inverter for the HRES application are compared with the results of the existing topologies to show the effectiveness of the proposed model.

 KEYWORDS:

1.      Battery energy storage system (BESS)

2.      Modified cascaded H-bridge Multi-level inverter (MCHBMLI)

3.      Total harmonic distortion (THD)

 SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, 9-level, 13-level and 17-level inverters are designed by employing modified cascaded MLI, followed by ANN as a control approach for the inverter. Using the ANN method, the MPP exactly searching when the solar irradiance changes sharply, and it can make the system work under a stable mode. The advantage of the ANN-based PV model method is the fast MPP approximation according to the parameters of the PV panel. The proposed new MPPT algorithm can search the MPP fast and exactly based on the feedback voltage and current with different solar irradiance and temperature of the environment. The simulations are performed in MATLAB/SIMULINK environment. The output voltage waveform shows less distortion with a reduced number of power switches and is validated by calculating THD as a performance measure. The results attained from the proposed model exhibits superiority over the previously suggested models when compared. The proposed modified system can be analyzed in the future, with different sources such as fuel cell, diesel generator, etc. in the standalone microgrid topology. This is more cost-effective due to the use of reduced number of switches and other components. Thus it helps in improving the total harmonic distortions as per the IEEE 519 standards, in terms of power quality of the islanded microgrid. The limitation of the proposed topology is that, in case of a failure of one ofH-bridges, theMLI can still be operated with decreased number of levels. However, full power cannot be supplied to the load. This can be improved by designing a fault tolerant MLI topology in the future.

REFERENCES:

1. M. A. Rosen, and I. Dincer, “Exergy as the confluence of energy, environment and sustainable development,” Exergy Int. J., Vol. 1, pp. 3–13, 2001.

2. P. Thongprasri. “Capacitor voltage balancing in the dc-link five-level full-bridge diode-clamped multilevel inverter,” 2016.

3. C. L. Kuppuswamy, and T. A. Raghavendiran. “FPGA Implementation of Carrier Disposition PWM for Closed Loop Seven Level Diode Clamped Multilevel Inverter in Speed Control of Induction Motor,” 2018.

4. F. Khoucha, S. M. Lagoun, K. Marouani, A. Kheloui, and M. El Hachemi Benbouzid, “Hybrid cascaded H-bridge multilevel-inverter induction-motor-drive direct torque control for automotive applications,” IEEE Trans. Ind. Electron., Vol. 57, no. 3, pp. 892–899, 2010.

5. V. Jammala, S. Yellasiri, and A. K. Panda, “Development of a new hybrid multilevel inverter using modified carrier SPWM switching strategy,” IEEE Trans. Power Electron., Vol. 33, no. 10, pp. 8192–8197, 2018.

A Modified Cascaded H-Bridge Multilevel Inverter For Solar Applications

 ABSTRACT:

In this paper, a modified cascaded H-bridge multilevel inverter (MLI) is proposed and designed for solar applications. Generally, as the level of conventional multilevel inverter increases, the required number of switches and size increases. The proposed topology is cascade of unit stages which involves 5 switches and two voltage source; moreover a unit stage is capable of generating 5 levels. Also, the detailed analysis of cascaded multilevel inverter is discussed which incorporates three different methodologies involving less number of power devices in order to generate maximum number of levels. This results into reduction in gate drive circuitry and less switching losses. The proposed MLI is designed for power 1.5kW and Inphase level shifting SPWM technique has been incorporated in which 5kHz carrier wave is compared with 50Hz of sinusoidal wave with a modulation index of 0.8. As a result, total harmonic distortion (THD) is achieved as 4.71% with LC-filter for above mentioned multilevel inverter. The circuits are modeled and simulated with the help of MATLAB/SIMULINK.

KEYWORDS:

1.      Modified cascaded H-bridge MLI

2.       Solar

3.      SPWM techniques

4.      Total Harmonic Distortions

 SOFTWARE: MATLAB/SIMULINK

 CONCLUSION:

In this paper, a new topology of modified cascaded H bridge MLI is designed for solar high power application. The three different methodologies have been analyzed and 9-level, 13-level and 17-level output is observed in the respective methodology. The number of switches used in the topology is less which in turn reduced the corresponding gate driving circuitry and made the circuit compact in size. The circuits of proposed MLI are simulated in MATLAB/SIMULINK and total harmonic distortions for the three methodologies are obtained by using FFT analysis window. The lowest THD observed with LC-filter is 4.71%. The proposed MLI is designed for power 1.5kW and In-Phase level shifting method is followed for the pulse generation for all three methodologies.

REFERENCES:

[1] Wei Zhao; Hyuntae Choi; G. Konstantinou; M. Ciobotaru; and V. G. Agelidis “Cascaded H-bridge Multilevel Converter for Large-scale PV Grid-Integration with Isolated DC-DC stage” PEDG, IEEE 2012.

[2] S. Rivera; S. Kouro; B. Wu; J. I. Leon; J. Rodriguez; and L. G. Franquelo "Cascaded H-bridge multilevel converter multistring topology for large scale photovoltaic systems," IEEE ISIE 2011, pp.1837-1844.

[3] N.A. Rahim; K. Chaniago; and J. Selvaraj "Single-Phase Seven-Level Grid Connected Inverter for Photovoltaic System", IEEE Transactions on Industrial Electronics, Vol. 58, No. 6, June 2011, pp. 2435-2443

[4] B. Singh; N. Mittal; and K. S. Verma “Multi-Level Inverter: A Literature Survey On Topologies And Control Strategies”, International Journal of Reviews in Computing, Vol. 10, July 2012, pp. 1-16

[5] Zhiguo pan; F .Z Peng; Victor Stefanoic; and Mickey Leuthen “A Diode-Clamped Multilevel Converter with Reduced Number of Clamping Diodes.”2004 IEEE.