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 pulse width 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

BLOCK DIAGRAM:

Figure 1. Cascaded H-Bridge Multilevel Inverter Power Circuit.

EXPECTED SIMULATION RESULTS:

Figure 2. Simulated Output Voltage And Current Waveforms Of The 7-Level Chb Mli With The Proposed Pwm Scheme. (A) Phase A Individual H-Bridge Output Voltages, (B) Phase-Leg Voltages, (C) Line Voltages, (D) Line Currents.

Figure 3. Simulated Dc-Link Voltages, Fft Analyses Of The Phase-Leg And Line Voltage Waveforms And Real Output Power Waveforms. (A) Dc-Link Voltages For The Whole Phases, (B) Fft Analysis Of The Phase-Leg Voltage Waveform From Ipd, Ps And Proposed Modulation Schemes, (C) Fft Analysis Of The Line Voltage Waveform From Ipd, Ps And Proposed Modulation Schemes, (D) Real Output Power Waveforms Of The Individual H-Bridges With The Proposed Spwm Scheme.

Figure 4. Experimental Output Voltages And Currents. (A) Each H-Bridge’s Output Voltage In Phase `A’, (B Phase-Leg Output Voltages In All The Phases, (C) Output Line Voltages, (D) Output Line Currents.

Figure 5. Experimental Dynamic Responses Of The Inverter System: (A), (B) Change In The Modulation Index Value At Constant Input Dc-Link Voltages; (C), (D) Change In The Input Dc-Link Voltages At Constant Output Load Current.

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 phase and 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. Sus- tain. 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.

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, the 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

BLOCK DIAGRAM:

Figure 1. Proposed h-type topology generating 5L.

EXPECTED SIMULATION REUSLTS:

Figure 2. Simulation results of the proposed 9L inverter for R = 30 W, L = 40mH a) Output voltage waveform with FFT spectrum, b) Output Current with FFT spectrum and (c) blocking voltage on switches P2, S3, S1, S6, S4.

Figure 3. Experimental results of Output voltage and current waveform for proposed 9L inverter (a) at load 30 W-40mH, dynamic load changes (b) from 50 W-60 mH to 30 W-40 mH, (c) from 30 W-40 mH to no-load (d) from no-load to 50 􀀀 60 mH and modulation index variations (e) from 0.4 to 0.6 and (f) from 0.6 to 1.0.

Figure 4. PCond;T , PCond;D , PSw;T , and PSw;D (a) at 0:5kW (b) at 1:0kW, (c) at 1:5kW\ (d) at 2:5kW (e) at 5:5kW and (f) Power Efficiency and Loss

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 pulse width modulation,” IEEE Transactions on Industrial Electronics, vol. 65, no. 6, pp. 4631–4639, 2018.

Active Power Filter for Harmonic Mitigation of Power Quality Issues in Grid Integrated Photovoltaic Generation System

ABSTRACT:

Single phase supply scheme tied with Photovoltaic arrangement (PV) employed on perturbed & observed (P&O) maximum energy point tracking technique with shunt active power filter allied to a rectifier feed R-L nonlinear load. The traditional Perturbed & Observed technique maximum energy point tracking topology is applied to attained maximum output power from Photovoltaic array(PVA), Proportional Integral conventional controller with phase detector (PD) phase locked loop (PLL) synchronization are executed to produce reference current. It provide at control unit of pulse width modulation topology( PWM) is utilized in inverter to get steady output voltage. Self supported DC bus PWM converter is regulated from PV array. In proposed architecture is minimized total harmonic pollution existing in supply current owing to power electronic load (PEL). Total current harmonic pollution (THDi) is compensated using dynamic filter shunt active power filter (SAPF) and power factor obtain better later than compensation. Hence, reactive power (KVAR) is delivered through system decrease and active power (KW) enhance. The suggested scheme has been implemented by way of MATLAB/SIMULINK 2015(a) environment.

KEYWORDS:

  1. Shunt Active Power Filter (SAPF)
  2. Photovoltaic Array (PVA)
  3. Proportional Integral controller
  4. Pulse width Modulated (PWM) Converter
  5. Maximum Power Point Tracking (P & O) Scheme

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

Fig.1 Suggested system schematic.

EXPECTED SIMULATION RESULTS:

Fig.2. PV array voltage before boosting.

Fig.3. DC link voltage

Fig.4. Power Factor

Fig.5. Source currents before compensation.

Fig.6. SAPF filter current.

Fig.7.Source current after comopensation as after 0.1 sec.

Fig.8. Graphical representation of active power

Fig.9. Graphical representation of reactive power

Fig.10. Source current harmonic spectrum befor compensation with

rectifier non linear diode load.

Fig.11. Source current harmonic graph after SAPF application.

CONCLUSION:

 In this research paper SAPF based on phase detector circuit (PLL) for unit vector generation with traditional PI controller is implemented. This controller regulates DC side voltage, reference current generated by PI conventional controller and positive progression predictor PLL synchronization unit. Hysteresis band current control(HBCC) is employed to produce gate signal for voltage source inverter (VSI). The source current THD is abridged to fewer than 5% that is in accordance IEEE-519 standards for harmonic. Active power is improved by dynamic filtering using SAPF and decrease in reactive power consequently, power factor level is become finer.

REFERENCES:

[1] M. Singh, V. Khadkikar, A. Chandra, and R. K. Varma,“Grid Interconnection of Renewable Energy Sources at the Distribution Level With Power-Quality Improvement Features” IEEE Transactions on Power Delivery, vol. 26, no. 1, January 2011.

[2] S. Agrawal, Seemant Chorsiya, D.K Palwalia, “Hybrid Energy Management System design with Renewable Energy Sources (Fuel Cells, PV Cells and Wind Energy): A Review”, IJSET, vol. 6, no. 3, pp.174-177, 2018. DOI : 10.5958/2277 1581.2017.00104.8.

[3] M. G. Villalva, J. R. Gazoli and E. R. Filho, “Modeling and circuitbased simulation of photovoltaic arrays”, Brazilian Power Electronics Conference, Bonito-Mato Grosso do Sul, pp. 1244-1254, 2009.

[4] S. Agrawal and D. K. Palwalia, “Analysis of standalone hybrid PVSOFC- battery generation system based on shunt hybrid active power filter for harmonics mitigation.” IEEE Power India International Conference (PIICON) pp. 1-6, 2016.

[5] M. M. Hashempour, M. Savaghebi, J. C. Vasquez and J. M. Guerrero, “A Control Architecture to Coordinate Distributed Generators and Active Power Filters Coexisting in a Microgrid”, IEEE Transactions on Smart Grid, vol. 7, no. 5, pp. 2325-2336, Sept. 2016.

A Novel V2V Charging Method Addressing the Last Mile Connectivity

ABSTRACT:

One of the main drawbacks in adopting EV vehicles is the last mile connectivity issue. There is always a chance that the user/rider may get stranded without EV charge and no EV charging stations nearby. With the aim of solving such an exigency, this paper proposes a novel V2V charging technique which allows charge transfer between two EVs off the grid, and discusses its modes of operation. Non-isolated bidirectional DC-DC converters with average current control technique are simulated in a MATLAB/Simulink environment to verify and validate the efficiency and charging time for the proposed charging technique.

KEYWORDS:

  1. V2V charging
  2. Bi-directional converter
  3. Pricing strategy

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1: Block diagram of V2V technology

EXPECTED SIMULATION RESULTS:

Figure 2: SOC% plots where higher SOC battery is charging and lower SOC battery is discharging

Figure 3: SOC% plots where higher SOC battery is discharging and lower SOC battery is charging

CONCLUSION:

A V2V charging scheme is proposed to synchronize the charging between two electric vehicles. This is particularly needed when an EV user is left stranded without battery charge and with no access to EV charging station. In this scenario, the proposed model allows another EV user to assist the stranded EV by charging from his EV thus solving last mile connectivity issues. The proposed model consists of a dual converter in the electric vehicle which enables fast DC charging or discharging. Extensive MATLAB simulation results on the model proves that the proposed work is capable of charging an EV from another under average current control method. The efficiency, SOC status and charging time for the proposed method is also analyzed. From the analysis it is evident that as the SOC difference increases the efficiency obtained also increases. To reduce the charging time and to enhance the efficiency average current control method is simulated and analyzed. The results obtained are presented and the results confirm the effectiveness of the proposed work.

V2V energy transfers which were reported in the earlier literature uses the concept of connected ad-hoc networks present in parking lots etc., where the vehicles parked in the parking lot are used for energy transfer through a connected bus in the parking lot itself. The term ‘novel’ has been used here as the issue of EV being left stranded without battery charge and with no access to charging station is not addressed anywhere in the literature and also the technique of using cascaded bi-directional converters for charging one vehicle from the other vehicle adds novelty to the V2V energy transfer. Cascaded Bidirectional converters can even facilitate the charge transfer when the electric vehicles battery voltage levels are different, that’s why cascaded converters has been employed.

REFERENCES:

[1] Markel, T., Saxena. S, Kahl. K, Pratt. R, “Multi-Lab EV Smart Grid Integration Requirements Study: Providing Guidance on Technology Development and Demonstration”, National Renewable Energy Laboratory. Retrieved 2016-03-08, 2005.

[2] Liu, Wei-Shih, Jiann-Fuh Chen, Tsorng-Juu Liang, Ray-Lee Lin, and Ching-Hsiung Liu, “Analysis, design, and control of bidirectional cascaded configuration for a fuel cell hybrid power system,” IEEE Transactions on Power Electronics 25,Vol. 6, 2010, pp no:- 1565-1575.

[3] Akshya, S., Anjali Ravindran, A. Sakthi Srinidhi, Subham Panda, and Anu G. Kumar, “Grid integration for electric vehicle and photovoltaic panel for a smart home.” 2017 International Conference on Circuit, Power and Computing Technologies (ICCPCT), pp. 1-8, 2017.

[4] Nagar, Ishan, M. Rajesh, and P. V. Manitha, “A low cost energy usage recording and billing system for electric vehicle,” International Conference on Inventive Communication and Computational Technologies (ICICCT), pp. 382-384, 2017.

[5] Rajalakshmi, B., U. Soumya, and Anu G. Kumar. “Vehicle to grid bidirectional energy transfer: Grid synchronization using Hysteresis Current Control”, International Conference on Circuit, Power and Computing Technologies (ICCPCT), pp. 1-6, 2017.

A New Five-Level Buck-Boost Active Rectifier

ABSTRACT:

In this paper a new single-phase five-level buck boost active rectifier is introduced called capacitor tied switches (CTS). The proposed rectifier has two independent DC outputs that can be connected to two different loads. Different switching states and the average mode of the proposed topology are analyzed to design the associated controller aims at regulating the two output DC voltages, generating five-level voltage at the input of the rectifier and finally draw unity power factor and sinusoidal current from AC grid. From AC grid view, the rectifier works in boost mode however the generated DC voltage can be split into two separate outputs which may be less than the AC peak voltage or even more leads to work in both buck and boost operation mode. Full simulation results are shown and analyzed to validate the effective operation and good dynamic performance of the proposed five-level buck-boost rectifier.

KEYWORDS:

  1. Multilevel converter
  2. Packed U-Cell
  3. Active PFC rectifier
  4. Buck-boost rectifier
  5. Capacitor Tied Switches (CTS)

SOFTWARE: MATLAB/SIMULINK

PROPOSED DIAGRAM:

Figure 1: proposed five-level buck-boost PFC rectifier (CTS)

EXPECTED SIMULATION RESULTS:

Figure 2: simulation results during change in DC voltages from 100 V to 200 V (transition between buck and boost modes). a) vs and is *current waveform multiplied by 4 b) power factor c) input voltage of the CTS rectifier Vad d) V1 e) V2

Figure 3: harmonic spectrum of Vad and is in buck mode (100 V DC output)

Figure 4: harmonic spectrum of Vad and is in boost mode (200 V DC output)

Figure 5: simulation results during load changes in buck mode. A) vs and is *current waveform is multiplied by 15 b) input voltage of the CTS rectifier Vad

c) V1 d) i1 e) V2 f) i2

Figure 6: simulation results during the loads changes in boost mode. A) vs and is *current waveform is multiplied by 15 b) input voltage of the CTS rectifier Vad

c) V1 d) i1 e) V2 f) i2

CONCLUSION:

In this paper a new topology of buck-boost active rectifier has been introduced based on slight modification of the third U-cell of the PUC original design. The proposed rectifier called CTS includes six switches tied by two capacitors as two output independent DC terminals and generates five-level voltage waveform at the input. The latter draw low harmonic current in-phase with the grid voltage making the operation at unity power factor rectifier easy in both buck and boost mode. This topology does not need additional bulky filters while switching at low frequency which constitute a big advantage of the presented CTS rectifier. Simulation results including regulated DC voltages, high power factor, and low supply THD current mainly obtained by the five-level rectifier input voltage. Moreover, good dynamic performance, fast response and reliable operation of the implemented controller and CTS converter topology were proven and discussed in details.

REFERENCES:

[1] B. Singh, B. N. Singh, A. Chandra, K. Al-Haddad, A. Pandey, and D. P. Kothari, “A review of single-phase improved power quality ACDC converters,” Industrial Electronics, IEEE Transactions on, vol. 50, pp. 962-981, 2003.

[2] B. Singh, B. N. Singh, A. Chandra, K. Al-Haddad, A. Pandey, and D. P. Kothari, “A review of three-phase improved power quality AC-DC converters,” Industrial Electronics, IEEE Transactions on, vol. 51, pp. 641-660, 2004.

[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] L. Yacoubi, K. Al-Haddad, L.-A. Dessaint, and F. Fnaiech, “Linear and nonlinear control techniques for a three-phase three-level NPC boost rectifier,” Industrial Electronics, IEEE Transactions on, vol. 53, pp. 1908-1918, 2006.

[5] L. Yacoubi, K. Al-Haddad, L.-A. Dessaint, and F. Fnaiech, “A DSPbased implementation of a nonlinear model reference adaptive control for a three-phase three-level NPC boost rectifier prototype,” Power Electronics, IEEE Transactions on, vol. 20, pp. 1084-1092, 2005.

The Fastest MPPT Tracking Algorithm for a PV array fed BLDC Motor Driven Air Conditioning system

ABSTRACT:

The fastest and novel adaptive voltage reference MPPT tracking algorithm for PV cluster sustained BLDC drive for aerating and cooling application is proposed in this paper. The fastest maximum power point tracking (MPPT) algorithm tracks the power instantaneously if there is any change in the solar irradiation. Low cost and energy efficiency is achieved by removing the conventional DC/DC boost converter stage which reduces the switching losses and further reduces the overall cost of the system thereby minimizing the power conversion stages. The proposed quickest MPPT algorithm for BLDC motor driven PV array fed air conditioning system is designed and modelled such that the performance is not affected even under the dynamic conditions. The proposed system is validated by simulation studies.

KEYWORDS:

  1. Instantaneous
  2. Low cost
  3. Efficient
  4. MPPT
  5. BLDC
  6. Air conditioner compressor

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of proposed system

EXPECTED SIMULATION RESULTS:

Fig. 2. Speed of BLDC Motor

Fig. 3. Torque of BLDC Motor

(a)

(b)

(c)

Fig. 4. stator back emf’s in phase a, phase b, phase c

(a)

(b)

(c)

Fig. 5. Stator currents in phase a,phase b, phase c

Fig. 6. Solar Insolation input for PV panel\

Fig. 7. PV panel Current(Ipv)Amps

Fig. 8. PV panel Power (watts)

Fig. 9. Tracking of MPPT power

Fig. 10. PV panel Voltage (Vpv) volts

CONCLUSION:

 In this study, a novel adaptive constant voltage reference MPPT technique was proposed to extort maximum power from solar panels and simultaneously uses PV voltage and current deviations to track the Maximum power point of a PV array under varying irradiance conditions has been presented in this paper. The fastest MPPT algorithm is simulated and discussed to extract maximum power from solar panels without using DC-DC converters thereby reducing switching losses which in turn increases r efficiency and reduces the cost for PV array fed BLDC Motor driven air conditioning system. The MATLAB simulation results effectively exhibit that, the proposed adaptive constant voltage MPPT algorithm works fine and shows good dynamic and steady state performance.

REFERENCES:

[1] Rodrigo A. Gonzalez, Marcelo A. Perez, Hugues Renaudineau and Freddy Flores-Bahamonde, “Fast Maximum Power Point Tracking Algorithm based on Switching Signals Modification,” IEEE International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG), pp. 448-453, 4-6 April 2017.

[2] Hassan Fathabadi, “Novel fast dynamic MPPT (maximum power point tracking) technique with the capability of very high accurate power tracking,”Elsevier journal Energy., Vol. 94, pp. 466-475, Jan. 2016.

[3] E. Mamarelis, G. Petrone and G. Spagnuolo, “Capacitor Peak Current Control for MPPT Photovoltaic Applications,” 39th Annual Conference of the IEEE Industrial Electronics Society, pp. 3347–3352, Nov 2013.

[4] Arash Kalantari , A.Rahmati and A.Abrishamifar, “A Faster Maximum Power Point Tracker Using Peak Current Control,” IEEE Symposium on Industrial Electronics and Applications, pp. 117–122, October 4-6, 2009.

[5] Neil S. D’Souza, Luiz A. C. Lopes, and Xuejun Liu, “Peak Current Control Based Maximum Power Point Trackers For Faster Transient  Responses,” Canadian Conference on Electrical and ComputerEngineering on 7-10 May 2006.

Real-Time Implementation of Model Predictive Control on 7-Level Packed U-Cell Inverter

ABSTRACT:

In this paper a model predictive control (MPC) has been designed and implemented on the Packed U-Cell (PUC) inverter which has one isolated DC source and one capacitor as an auxiliary DC link. The MPC is designed to regulate the capacitor voltage at the desired magnitude to have seven voltage levels at the output of the inverter. Since grid-connected application is targeted by this application, the inverter should be capable of supplying requested amount of active and reactive power at the point of common coupling (PCC) as well. Therefore, MPC should also consider the line current control in order to monitor the exchange of reactive power with the grid while injecting appropriate active power at low THD. Various experimental tests including change in DC source voltage, active power variation and operation at different power factor (PF) have been performed on a laboratory prototype to validate the good performance obtained by the proposed MPC. The dynamic performance of the controller during sudden changes in dc capacitor voltage, supply current and PF demonstrates the fast and accurate response and the superior operation of the proposed controller.

KEYWORDS:

  1. PUC Inverter
  2. Multilevel Inverter
  3. Model Predictive Control
  4. Grid-Connected PV
  5. Power Quality

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. General Scheme for MPC

EXPECTED SIMULATION RESULTS:

Fig. 2. Steady state voltage and current waveforms for grid-connected PUC.

Fig. 3 Results during 20% grid voltage variation (from 140V to 110V peak).

Fig. 4. Response to transient DC bus voltage changes.

Fig. 5. Controller response to reactive power variations.

Fig. 6. Experimental results showing grid current reference amplitude 100%

increase and thereafter 50% decrease.

CONCLUSION:

In this paper, a Model Predictive Control has been designed for the 7-level PUC inverter in grid-connected mode of operation, an excellent candidate for photovoltaic and utility interface application to deliver green power to the utility. MPC is a simple and intuitive method that does not have confusing gains to adjust as well as featuring fast response during any change in the system parameters. Experimental results have been provided to show the fast response of the implemented controller on the grid-connected multilevel PUC inverter. It has been demonstrated that the DC link capacitor voltage has been regulated at desired level and 7-level voltage waveform has been generated at the output of the inverter. The injected current to the grid was successfully controlled to have regulated amplitude and synchronized waveform with the grid voltage to deliver maximum power with unity power factor. Moreover, the PF has been controlled easily to exchange reactive power with the grid while injecting the available active power. Exhaustive experimental results including change in the grid current reference, DC source and AC grid voltages variations, as well as PF have been tested and results have been illustrated which ensured the good dynamic performance of the proposed controller applied on the grid connected PUC inverter.

REFERENCES:

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

[2] 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.

[3] J. M. Carrasco, L. G. Franquelo, J. T. Bialasiewicz, E. Galván, R. P. Guisado, M. A. Prats, J. I. León, and N. Moreno-Alfonso, “Powerelectronic systems for the grid integration of renewable energy sources: A survey,” IEEE Trans. Ind. Electron., vol. 53, no. 4, pp. 1002-1016, 2006.

[4] M. G. Kashani, M. Mobarrez, and S. Bhattacharya, “Variable interleaving technique for photovoltaic cascaded DC-DC converters,” in IECON 2014-40th Annual Conference of the IEE EIndustrial Electronics Society, 2014, pp. 5612-5617.

[5] M. Mobarrez, M. G. Kashani, G. Chavan, and S. Bhattacharya, “A Novel Control Approach for Protection of Multi-Terminal VSC based HVDC Transmission System against DC Faults,” in ECCE 2015- Energy Conversion Congress & Exposition, Canada, 2015, pp. 4208- 4213.

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

BLOCK DIAGRAM:

Fig. 1. Three-phase 3-wire/4-wire configuration of PUC inverter

EXPECTED SIMULATION RESULTS:

Fig. 2. Test results of a 7-Level PUC rectifier

Fig. 3. Test results of a sensor-less 5-Level PUC standalone inverter

Fig. 4. Test results of a Sensor-less 5-Level PUC grid-connected inverter

Fig. 5. Experimental results of 5-level PUC converter as STATCOM

Fig. 6. Three-phase 5-level PUC inverter voltage and current waveforms

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 neutralpoint- 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.

Real-Time Implementation of a Packed U-Cell Seven-Level Inverter with Low Switching Frequency Voltage Regulator

ABSTRACT:

In this paper a new cascaded nonlinear controller has been designed and implemented on the packed U-Cell (PUC) seven-level inverter. Proposed controller has been designed based on a simplified model of PUC inverter and consists of a voltage controller as outer loop and a current controller as inner loop. The outer loop regulates the PUC inverter capacitor voltage as the second DC bus. The inner loop is in charge of controlling the flowing current which is also used to charge and discharge that capacitor. The main goal of the whole system is to keep the DC capacitor voltage at a certain level results in generating a smooth and quasi-sine-wave 7-level voltage waveform at the output of the inverter with low switching frequency. The proposed controller performance is verified through experimental tests. Practical results prove the good dynamic performance of the controller in fixing the PUC capacitor voltage for various and variable load conditions and yet generating low harmonic 7-level voltage waveform to deliver power to the loads. Operation as an uninterruptible power supply (UPS) or AC loads interface for photovoltaic energy conversion applications is targeted.

KEYWORDS:

  1. Packed U-Cell
  2. Multilevel Inverter
  3. Voltage Balancing
  4. Nonlinear Controller
  5. Renewable energy conversion

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of proposed controller applied on 7-level PUC inverter

EXPECTED SIMULATION RESULTS:

Fig. 2. PUC inverter voltage and current waveforms in steady state condition

Fig. 3. Voltage regulation during a fast 66% increase in DC source amplitude

Fig. 4. Adding a nonlinear load (rectifier) to the PUC inverter while supplying an RL load

CONCLUSION:

In this paper a new cascaded nonlinear controller has been designed for 7-level PUC inverter based on the simple model derived by multilevel inverter topology concept. Experimental results showed appropriate dynamic performance of the proposed controller in stand-alone mode as UPS, renewable energy conversion system or motor drive applications. Different changes in the load and DC bus voltage have been made intentionally during the tests to challenge the controller reaction in tracking the voltage and current references. Proposed controller demonstrated satisfying performance in fixing the capacitor voltage of the PUC inverter, generating seven-level voltage with low harmonic content at the output of the PUC inverter and ensures low switching frequency operation of those switches. By applying the designed controller on the 7-level PUC inverter it can be promised to have a multilevel converter with maximum voltage levels while using less active switches and DC sources aims at manufacturing a low-cost converter with high efficiency, low switching frequency, low power losses and also low harmonic contents without using any additional bulky filters.

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] J. M. Carrasco, L. G. Franquelo, J. T. Bialasiewicz, E. Galván, R. P. Guisado, M. A. Prats, et al., “Power-electronic systems for the grid integration of renewable energy sources: A survey,” IEEE Trans. Ind. Electron., vol. 53, no. 4, pp. 1002-1016, 2006.

[3] M. Mobarrez, M. G. Kashani, G. Chavan, and S. Bhattacharya, “A Novel Control Approach for Protection of Multi-Terminal VSC based HVDC Transmission System against DC Faults,” in ECCE 2015- Energy Conversion Congress & Exposition, Canada, 2015, pp. 4208- 4213.

[4] B. Singh, A. Chandra, and K. Al-Haddad, Power Quality: Problems and Mitigation Techniques: John Wiley & Sons, 2014.

[5] B. Singh, K. Al-Haddad, and A. Chandra, “A review of active filters for power quality improvement,” IEEE Trans. Ind. Electron., vol. 46, no. 5, pp. 960-971, 1999.

Multicarrier-SPWM Based Novel 7-Level Inverter Topology with Photovoltaic System

 ABSTRACT:

In this paper a novel 5 switch seven level DC-AC inverter is being proposed. The proposed multilevel inverter uses reduced number of switches as compared to the switches used in the conventional multilevel inverter. The inverter has been designed to generate a 7 level AC output using 5 switches. The voltage stress on each of the switches as well as the switching losses is found to be less, minimized common mode voltage (CMV) level and reduced total harmonic distortion. The proposed 7-level inverter topology has four dc sources, which is energized through the PV system. Proposed inverter is controlled with help of multicarrier sinusoidal pulse width modulation (MCSPWM).The simulation and hardware results were verified using matlab simulink and dspic microcontroller respectively.

KEYWORDS:

  1. DsPIC controller
  2. Multicarrier sinusoidal pulse width modulation (MCSPWM)
  3. Multilevel inverter
  4. PV system

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Figure 1. Novel 7 Level 5switch inverter topology

EXPECTED SIMULATION RESULTS:

Figure 2. 7-level stepped output voltage of proposed system

Figure 3. Output current of proposed system inverter topology

Figure 4. Switching pulses generation using MCSPWM

Figure 5. Voltage across the switches placed in the proposed inverter

(a)

(b)

Figure 6. THD analysis of proposed system (a) output voltage (b) output current

CONCLUSION:

In this proposed paper, the multicarrier sinusoidal pulse width modulation scheme was implemented to produce a seven level stepped output voltage with reduced harmonics. The proposed inverter energized by using photovoltaic system, which boosted through the boost converter. Also this system which minimises the common mode voltage level, voltage stress across the various switches improves output and better current control is accomplished. And the simulation and experimental results were verified using matlab16 and dspic controller respectively.

REFERENCES:

[1] Poh Chiang Loh, Feng Gao, FredeBlaabjerg, and Sokweilim,” Operational Analysis and Modulation Control of Three-Level Z-Source Inverters With Enhanced Output Waveform Quality,”IEEE Transaction On Power Electronics, Vol.24, No.7, July 2009.

[2] SamirKouro, Pablo Lezana, Mauricio Angulo and José Rodríguez, ”Multicarrier PWM with Dc-Link Ripple Feedforward Compensation For Multilevel Inverters,” IEEE Transactions on Power Electronics, Vol. 23, No.1, January2010.

[3] S. Mohamed Yousuf, P. Vijayadeepan, Dr. S. Latha, “The Comparative THD Analysis of Neutral Clamped Multilevel Z-source Inverter Using Novel PWM Control Techniques” IJMER Vol.2, Issue.3, May-June 2012 pp-1086-1091.

[4] Huafeng Xiao, ShaojunXie, Chen Yang, “Transformerless Split-inductor Neutral point clamped Three-level PV Grid-Connected Inverter” IEEE Energy Conversion congress and Exposition (ECCE), 2010 pp. 2929-2936

[5] Bharatiraja, C., Raghu, S., Rao, P., Paliniamy, K.R.S. “Comparative analysis of different PWM techniques to reduce the common mode voltage in three-level neutral-point- clamped inverters for variable speed induction drives”, International Journal of Power Electronics and Drive Systems, vol. 3, Issue 1, March 2013, Pages 105-116.