Adaptive Power Decoupling Control for Single-Phase Converter with Unbalanced DC-Split-Capacitor Circuit

 ABSTRACT:

This paper proposes an adaptive power decoupling control strategy for a single-phase rectifier with an unbalanced split-capacitor decoupling circuit. Since a capacitance mismatch estimator is integrated into the control strategy, the impact of capacitance mismatch is eliminated. Meanwhile, the capacitance mismatch estimator can provide an auxiliary online monitor for the health of split-capacitors. Moreover, the mechanism of capacitor voltages self-balance is explained. Finally, experiments are conducted to verify the effectiveness of the proposed method.

KEYWORDS:

1.      Active power decoupling

2.       Adaptive control

3.      Dc split- capacitor

4.      Single-phase converter

5.      Capacitance mismatch

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

Fig. 1. Proposed control diagram for single-phase power converter with DC split- capacitor power decoupling circuit.

 

EXPECTED SIMULATION RESULTS:

Fig. 2. Simulation results of the proposed adaptive decoupling controller. (a) Case I; (b) Case II; (c) Case III.

 

CONCLUSION:

In this paper, an adaptive power decoupling controller is proposed for the DC split-capacitor decoupling circuit under  capacitance mismatch. The conclusions are listed below: 1) The steady-state analysis of DC split-capacitor decoupling circuits shows that there are infinite feasible solutions to achieve the decoupling of twice ripple power under capacitance mismatch. Among them, a special solution is to control the capacitor voltages into DC and the fundamental frequency sinusoidal AC component. 2) Under the framework of the special solution, an adaptive power decoupling controller is proposed to realize the decoupling of twice ripple power. 3) The capacitance mismatch estimator is presented to estimate the unequal factor online. Consequently, the fundamental frequency power ripple caused by capacitor mismatch is eliminated. Meanwhile, the estimated unequal factor can be used as a health monitoring indicator of split-capacitors.

REFERENCES:

[1] Y. Sun, Y. Liu, M. Su, W. Xiong, and J. Yang, “Review of active power decoupling topologies in single-phase systems,” IEEE Transactions on Power Electronics, vol. 31, no. 7, pp. 4778–4794, Jul. 2016.

[2] H. Hu, S. Harb, N. Kutkut, I. Batarseh, and Z. J. Shen, “A review of power decoupling techniques for microinverters with three different decoupling capacitor locations in PV systems,” IEEE Transactions on Power Electronics, vol. 28, no. 6, pp. 2711–2726, Jun. 2013.

[3] Y. Yang, X. Ruan, L. Zhang, J. He, and Z. Ye, “Feed-forward scheme for an electrolytic capacitor-less AC/DC LED driver to reduce output current ripple,” IEEE Transactions on Power Electronics, vol. 29, no. 10, pp. 5508–5517, Oct. 2014.

[4] H. Li, K. Zhang, and H. Zhao, “Dc-link active power filter for highpower single-phase pwm converters,” J. Power Electron., vol. 12, no. 3, pp. 458–467, May 2012.

[5] R. Wang, F. Wang, D. Boroyevich, R. Burgos, R. Lai, P. Ning, and K. Rajashekara, “A high power density single-phase pwm rectifier with active ripple energy storage,” IEEE Transactions on Power Electronics, vol. 26, no. 5, pp. 1430–1443, May 2010.

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. Per Phase Block Diagram Of The Multilevel Waveform Template, Mwt, Generation.

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. Inverter Conduction And Switching Losses For Modulation Index Range Of 0.6 To 1.

 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 high voltage 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 ef_cient 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 Single Phase, Single Stage AC-DC Multilevel LLC Resonant Converter With Power Factor Correction

ABSTRACT:

Single stage LLC resonant converters with inherent power factor correction are getting popularity in AC-DC converters due to its reduced size and weight. However, single stage topologies are usually less efficient in regulating the dc bus capacitor voltage pertaining to line and load transients. This paper proposes a multi-level flying capacitor based single stage AC-DC LLC topology to address the issue of voltage balancing of dc-bus capacitor and to reduce the voltage stress of the switching devices. The proposed three-level inverter topology guarantees zero voltage switching, less circulating currents, reduced switching stress and losses. The converter uses bridgeless rectification scheme for better efficiency and the power factor is made nearly unity by operating the source-side inductor in discontinuous current conduction. Variable switching frequency control is used to regulate the output voltage of the converter and pulse width modulation is used to control the dc-bus voltage. This dual control scheme is very effective to keep the dc-bus voltage nearly constant over a wide range of line and load variations. The proposed topology and control scheme have been validated by hardware results on a 250W resistive load.

KEYWORDS:

1.      LLC resonant converters

2.      AC-DC converters

3.      soft switching

4.       PFC

5.      THD

6.      DC bus

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Figure 1. Proposed Three-Level Single Stage Llc Converter.

 

EXPECTED SIMULATION RESULTS:

Figure 2. Source Voltage And Current Waveform.

Figure 3. Input Current Waveform Through Input Inductor.

Figure 4. Flying Capacitor Voltage Waveform, Vc1.

Figure 5. Dc Bus Voltage Waveform, Vc1 C Vc2.

 

CONCLUSION:

This paper has proposed a three-level flying capacitor based topology for AC/DC LLC resonant converters. The converter has a bridgeless topology which reduces the number of con- ducting devices. The controller uses a dual control scheme which varies duty ratio and frequency to regulate DC bus and output DC voltages respectively. The converter is designed to operate in discontinuous conduction mode to obtain a near unity power factor without having any active current control techniques. Furthermore, the topology provides low voltage stress, ZVS for all the four switches, and reduces losses. For verification, a 250W, 230V to 48V AC-DC converter proto- type has been designed and implemented. The DC bus voltage is held constant at 750V with a peak overshoot of 3.3% even when the load is reduced by 30% from full load.

REFERENCES:

[1] A. K. Peter and J. Mathew, ``A three-level half-bridge flying capacitor topology for single-stage AC-DC LLC resonant converter,'' in Proc. IEEE Int. Conf. Power Electron., Drives Energy Syst. (PEDES), Dec. 2018,pp. 1_6.

 [2] A. Hillers, D. Christen, and J. Biela, ``Design of a highly efficient bidirectional isolated LLC resonant converter,'' in Proc. 15th Int. Power Electron. Motion Control Conf. (EPE/PEMC), Sep. 2012, pp. DS2b_13.

[3] J.-H. Kim, M.-Y. Kim, C.-O. Yeon, and G.-W. Moon, ``Analysis and design of boost-LLC converter for high power density AC-DC adapter,'' in Proc. IEEE ECCE Asia Downunder, Jun. 2013, pp. 6_11.

[4] Y. Qiu, W. Liu, P. Fang, Y.-F. Liu, and P. C. Sen, ``A mathemati- cal guideline for designing an AC-DC LLC converter with PFC,'' in Proc. IEEE Appl. Power Electron. Conf. Expo. (APEC), Mar. 2018, pp. 2001_2008.

[5] S.-Y. Chen, Z. R. Li, and C.-L. Chen, ``Analysis and design of single-stage AC/DC LLC resonant converter,'' IEEE Trans. Ind. Electron., vol. 59, no. 3, pp. 1538_1544, Mar. 2012.

A Novel High-Gain Soft-Switching DC-DC Converter With Improved P&O MPPT for Photovoltaic Applications

ABSTRACT:

This paper proposes a novel high voltage gain structure of DC-DC converter with soft-switching ability for photovoltaic (PV) applications. A small size coupled inductor with one magnet core is utilized to improve the voltage conversion ratio in the proposed converter. The converter has one active MOSFET with low conducting resistance (RDS􀀀ON ), which in turn reduces the conduction losses and complexity of the control section. Due to the low input current ripple, the lifetime of the input PV panel is increased, and the maximum power point (MPP) of the PV panel can be easily tracked. The MOSFET's zero-voltage and zero-current switching and diodes are the other countenance of the proposed converter, which improve its efficiency. Additionally, an improved Perturb and Observe MPP tracking (IP&O MPPT) algorithm is introduced to boost the extracted power of the input PV sources. To validate the performance of this converter, the operation modes principle, steady-state and efficiency survey, and comparison results with other same family converters are carried out. Finally, an experiential prototype is built with 20 V input, 200 V output, power rate of 200W, and 50 kHz operating frequency to validate the mathematical analysis and effectiveness of the proposed structure. The efficiency of the proposed converter was estimated by over 95% at various power levels.

KEYWORDS:

1.      Perturb and observe algorithm

2.      Dc-dc converter

3.      Photovoltaic

4.      MPPT

5.      Zero current switching

6.      High efficiency

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

 

 

Figure 1. Schematic Diagram Of The Non-Isolated High Step-Up Dc-Dc Converter For Pv Applications.

 

Figure 2. Structure Of The Proposed High Step-Up Dc-Dc Converter For Pv Systems.

 

EXPECTED SIMULATION RESULTS:

Figure 3. Simulation Result Of The Capacitor Voltages.

 

Figure 4. Simulation Result Of The Capacitor Voltages Of The Proposed Converter, (A) Vo-Vin, (B) Iin.

 

Figure 5. Simulation Result Of The Capacitor Voltages Proposed, (A) Vd1-Id1, (B) Vd2-Id2, (C) Vdo-Ido And (D) Vsw -Isw:

CONCLUSION:

This paper proposed a novel structure of non-isolated DC-DC converter with high voltage gain and soft-switching capability for PV applications. The presented converter benefits from 1) high voltage gain, 2) low input current ripple, 3) high efficiency, 4) simple structure, 5) peak voltage throughout the semiconductor components and 6) low components count. In the presented non-isolated DC-DC converter, a small size and cost coupled inductor with one magnet core is used to increase the voltage conversion ratio. The suggested topology has only one active MOSFET with lower conducting resistance (RDS􀀀ON ), which can decrease the control section's conduction losses and complexity. Due to the low input current ripple, the lifetime of the input PV panel is increased and the MPP of the PV panel can be easily tracked. Soft switching conditions include ZVS and ZCS of power MOSFET, and diodes are the other features of the proposed converter which improve efficiency. Additionally, an improved P&O MPPT algorithm is suggested to increase the extracted power from the input PV sources. In the rest of this paper, to verify the performance of the suggested converter, the operation modes principle, steady-state and efficiency calculation, and comparison results with other similar converters are provided. The outcomes of this study proved the theoretical analysis and the efficiency of higher than 95% at different power levels.

REFERENCES:

[1] M. Mostafa, H. M. Abdullah, and M. A. Mohamed, ``Modeling and experimental investigation of solar stills for enhancing water desalination process,'' IEEE Access, vol. 8, pp. 219457_219472, 2020.

[2] M. A. Mohamed, A. A. Z. Diab, and H. Rezk, ``Partial shading mitigation of PV systems via different meta-heuristic techniques,'' Renew. Energy, vol. 130, pp. 1159_1175, Jan. 2019.

[3] A. M. Eltamaly, Y. Sayed Mohamed, A.-H. M. El-Sayed, M. A. Mohamed, and A. Nasr A. Elghaffar, ``Power quality and reliability considerations of photovoltaic distributed generation,'' Technol. Econ. Smart Grids Sustain.z Energy, vol. 5, no. 1, pp. 1_21, Dec. 2020.

[4] S. Mishra, K. Bhargava, and D. Deb, ``Numerical simulation of potential induced degradation (PID) in different thin-_lm solar cells using SCAPS- 1D,'' Sol. Energy, vol. 188, pp. 353_360, Aug. 2019.

[5] M. A. Mohamed, H. M. Abdullah, A. S. Al-Sumaiti, M. A. El-Meligy, M. Sharaf, and A. T. Soliman, ``Towards energy management negotiation between distributed AC/DC networks,'' IEEE Access, vol. 8, pp. 215438_215456, 2020.

A Non-Inverting High Gain DC-DC Converter With Continuous Input Current

ABSTRACT:

High gain DC-DC converters are increasingly being used in solar PV and other renewable generation systems. Satisfactory steady-state and dynamic performance, along with higher efficiency, is a pre-requirement for selecting the converter for these applications. In this paper, a non-inverting high gain DC-DC boost converter has been proposed. The proposed converter has only one switch with continuous input current and reduced voltage stress across switching devices. The operating range of the duty cycle is wider, and it obtains a higher gain at a lower value of the duty cycle. Moreover, the converter has higher efficiency at a lower duty cycle while drawing a continuous input current. The continuous input current is a desirable feature of the dc-dc converter making it suitable for solar photovoltaic applications. The converter's operation has been discussed in detail and extended to include the real circuit parameters for a practical performance evaluation. The proposed converter has been compared with other similar recently proposed converters on various performance parameters. The loss analysis for the proposed converter has also been carried out. Finally, the simulation has been validated with results from the experimental prototype.

KEYWORDS:

1.      Continuous conduction mode

2.      Duty cycle

3.      High gain

4.      DC-DC boost converter

5.      Voltage stress

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

Figure 1. (A) Conventional Quadratic Boost Converter (Cqbc) (B) Proposed Converter In [26] (C) Proposed Converter.

EXPECTED SIMULATION RESULTS:

Figure 2. Simulated Waveforms Of Il1 And Il2 And Vgs1 At D D 0.3.

Figure 3. Simulated Waveforms Of V0 And Vin At D D 0.3 With Vgs1.

 

Figure 4. Simulated Waveforms Of Input Current Iin At D D 0.3.

 

Figure 5. Simulated Waveforms Of Vc1, Vc3 And Vc4 At D D 0.3.

 

Figure 6. Simulated Waveforms Of Vd5, Vs1 And Vgs1 At D D 0.3.

 

CONCLUSION:

A new non-inverting DC-DC boost converter is proposed in this paper. The proposed converter has high gain and utilizes only one switch to operate the converter, and therefore, control is easy. The voltage stress on the switch and diodes is low, and therefore low voltage-rated switch can be chosen which increases the efficiency and reduces the cost. The converter has draws continuous input current and thus the need for an input filter does not arise. Hence, it can be used in microgrid applications as the voltage of the converter at a low duty ratio is high compared to the conventional boost converter and other high gain converters. To verify the analysis practically, a 200W hardware prototype has been prepared for the converter. The peak of the efficiency of the proposed converter is observed to be greater than 95% but the efficiency decreases at high output power on account of losses. Thus, the proposed converter is suitable for medium power range suitably up to 300W. The merits of the converter make it suitable to be used in solar PV applications, automobiles, fuel cells and electric vehicles.

REFERENCES:

[1] D. Habumugisha, S. Chowdhury, and S. P. Chowdhury, ``A DC_DC interleaved forward converter to step-up DC voltage for DC microgrid applications,'' in Proc. IEEE Power Energy Soc. Gen. Meeting, Vancouver, BC, Canada, Jul. 2013, pp. 1_5, doi: 10.1109/PESMG.2013.6672501.

[2] P. K. Maroti, M. S. B. Ranjana, and D. K. Prabhakar, ``A novel high gain switched inductor multilevel buck-boost DC_DC converter for solar applications,'' in Proc. IEEE 2nd Int. Conf. Electr. Energy Syst. (ICEES), Chennai, India, Jan. 2014, pp. 152_156, doi: 10.1109/ICEES.2014. 6924159.

[3] A. Sarikhani, B. Allahverdinejad, and M. Hamzeh, ``A nonisolated buckboost DC_DC converter with continuous input current for photovoltaic applications,'' IEEE J. Emerg. Sel. Topics Power Electron., vol. 9, no. 1, pp. 804_811, Feb. 2021, doi: 10.1109/JESTPE.2020.2985844.

[4] F. L. Tofoli, D. D. C. Pereira, W. J. de Paula, and D. D. S. Oliveira, Jr., ``Survey on non-isolated high-voltage step-up DC_DC topologies based on the boost converter,'' IET Power Electron., vol. 8, no. 10, pp. 2044_2057, Oct. 2015, doi: 10.1049/iet-pel.2014.0605.

[5] S.-Y. Tseng and C.-Y. Hsu, ``Interleaved step-up converter with a singlecapacitor snubber for PV energy conversion applications,'' Int. J. Electr. Power Energy Syst., vol. 53, pp. 909_922, Dec. 2013.