Differential Power Processing Research Articles

Power equalization and optimization of photovoltaic module based on forward-flyback converter

This paper focuses on enhancing the energy extraction efficiency of photovoltaic (PV) modules through the use of a straightforward power converter and control algorithm. This research delves into the electrical characteristics of PV modules, explaining the concepts of global maximum power point, and local maximum power points. By integrating maximum power point tracking algorithms and differential power processing technology, an innovative scheme for power equalization and optimization of PV modules is introduced. The scheme is based on a single-switch multi-winding forward-flyback converter. Using the STP-340-72-Vfh-type PV module as a case study, a simulation model is developed with PLECS simulation software. The simulations cover 30 different irradiance scenarios. The findings illustrate the effectiveness of the proposed PV module power optimization system in achieving maximum power output under different irradiance conditions, achieving an average efficiency of 94.61%. This efficiency rate is 13.95% greater than that of existing global maximum power tracking schemes.

Performance analysis of modified residential PV system configuration under mismatch conditions

Partial shading is a prevalent phenomenon with a substantial impact on PV system performance. Various techniques, such as maximum power tracking (MPPT), PV module interconnection, and power electronics-based schemes, have been employed to address these challenges at both the module level and the submodule level. Existing methods face limitations related to the cost of hardware and the complexity of control systems. These limitations hinder the widespread application of current solutions. Also, Module-level techniques though simple and economical provide limited granularity. The choice between these techniques involves a trade-off between complexity, cost, adaptability, and the specific characteristics of the PV system and its operating environment.This paper presents a new hybrid submodule-level partial shading mitigation scheme based on TCT interconnection and differential power processing. The proposed system, emphasizing its role in enhancing overall PV system performance offers a cost-effective, and easy-to-control solution. To compare and validate the performance of proposed hybrid architecture, a practically installed single-phase grid tied central inverter 3 kW residential PV system is considered. This practical PV system is modified to hybrid architecture and the performance parameters such as power generation, mismatch power loss, fill factor, power conversion efficiency and power improvement calculated for different operating conditions. The results show that the modified conventional PV system mitigate the mismatch issue effectively and improves the output performance for any operating condition

A Compact Cuk-Based Differential Power Processing IC With Integrated Magnetics and Soft-Switching Controller for Maximized Cell-Level Power Extraction

A Compact Cuk-Based Differential Power Processing IC With Integrated Magnetics and Soft-Switching Controller for Maximized Cell-Level Power Extraction

Novel differential power processing technique for uneven partial shading mitigation in PV systems

Photovoltaic (PV) system output power greatly depends on environmental operating conditions. Partial shaded condition (PSC) operates PV string under mismatch. PV module mismatch has been one of the major causes for reduced amount of output power. Maximizing the amount of energy extraction from PV system under mismatch greatly influenced by conversion efficiency as well as the mismatch mitigation topology used. Differential power processing (DPP) is one of the advanced techniques to deal with mismatch conditions and enhance power output from a PV system. In this paper hybrid modular DPP topology is presented. The proposed technique mitigates the effect of mismatches at submodule and enhance power extraction from PV string. Since in majority shading on a PV module is nonuniform. The conversion efficiency of module level DPP shading mitigation techniques enhanced using submodule level DPP architecture. To demonstrate its applicability simulation study is carried out in MATLAB Simulink and results are compared with traditional bypass method and module level DPP. Simulation results showed the reduction in mismatch loss and improvement in efficiency and power output.

Performance analysis of optimized differential power processing converter with switched inductor using enhanced fuzzy logic control for solar photovoltaic systems

In the current landscape of renewable energy systems, optimizing the performance of power electronic converters is crucial for ensuring reliability. Within the realm of direct current (DC)–DC power converter systems, the differential power processing (DPP) converter holds promise. However, realizing its full potential requires meticulous system design, especially in response to varying solar irradiation levels. Poor design can result in performance degradation, leading to system damage and voltage instability due to sudden irradiation fluctuations. To address these challenges, this study investigates the performance optimization of a DPP converter enhanced with a modified switched inductor, tailored for solar photovoltaic applications. To overcome traditional control strategy limitations, we propose an innovative enhanced fuzzy logic controller (E-FLC). This controller’s strength lies in its dynamic adaptability, achieved through variable duty cycle control, input parameters, membership functions, and output responses. This paper emphasizes methodological precision, particularly in applying the E-FLC to the modified switched inductor. The use of this controller significantly improves both steady-state and transient response performance compared to traditional switched inductors. It rigorously analyzes the responses of the DPP converter under steady-state and transient conditions, with and without the modified switched inductor. This analytical approach sheds light on a critical yet often overlooked aspect of photovoltaic systems. The core innovation driving this research is the adoption of the E-FLC, which outperforms the commonly used proportional–integral (PI) controller in steady-state performance and transient response characteristics. This paper goes beyond conventional converter optimization studies by introducing a holistic approach encompassing system dynamics, control strategy innovation, and performance evaluation. The proposed E-FLC represents a methodological breakthrough and a substantial improvement in converter efficiency and reliability. As renewable energy continues to reshape the global energy landscape, this research sets a new standard for harnessing the true capabilities of power electronic converters in solar photovoltaic systems.

Performance Quantization and Comparative Assessment of Voltage Equalizers in Mismatched Photovoltaic Differential Power Processing Systems

Performance Quantization and Comparative Assessment of Voltage Equalizers in Mismatched Photovoltaic Differential Power Processing Systems

A Modular Differential Power Processing Converter Design with Simplified Voltage Equalization for Photovoltaic Systems

Partial shading in series-connected photovoltaic (PV) systems poses a significant challenge as it considerably restricts the system’s output power and has a notable impact on the overall efficiency. Differential power processing (DPP) has emerged as a widely employed solution to mitigate this effect. However, implementing DPP architectures introduces challenges such as system cost, reliability, control implementation, and modularity. This research proposes a simplified voltage equalization (VE) algorithm, executed on a low-cost and modular DPP architecture using bi-directional flyback converters. Notably, under light and moderate partial shading conditions, the PV system’s output power exhibits a significant increase compared to the traditional string configuration with bypass diodes. To further optimize the system performance, a methodology adapted to the VE algorithm is suggested, minimizing the processed power while increasing overall efficiency. The proposed solutions have undergone rigorous testing through simulations and experiments. The results validate that, under moderate shading conditions, the system efficiency reaches approximately 90%.

Differential power processing architecture to increase energy harvesting of photovoltaic systems under permanent mismatch

Differential power processing (DPP) architectures are a prominent solution for mitigating undesirable issues caused by mismatch that often occurs in photovoltaic (PV) strings. In this scenario, the association of DPP converters in parallel with PV strings is a common approach for enhancing energy harvesting. However, most topologies presented so far focus on temporary mismatch caused by partial shading conditions only, with little attention given to permanent mismatch due to the connection of modules with distinct ratings. Given the above, this article presents a novel DPP topology capable of handling both temporary and permanent mismatch in PV strings. Important advantages include lower component count; reduced voltage stresses on the active switches; operation under zero-current switching (ZCS) condition, with a direct impact on the converter efficiency; and greater design flexibility in terms of a modular solution that can be implemented at the PV module level. Experimental tests on a string composed of six modules are presented and the results are thoroughly discussed to validate the theoretical assumptions. It is effectively demonstrated that the architecture allows for increasing the power extracted from the string under two severe operating conditions.

Coupling Analysis of Differential Power Processing-Based PV System and Its Decoupling Implementation of Synchronous MPPT Control

Differential power processing (DPP) is considered to be a highly competitive architecture for photovoltaic (PV) applications due to its characteristics, such as high energy efficiency and mitigation of mismatch issues. However, the complexity of coupling between DPP converters poses challenges in terms of maximum power point tracking (MPPT) in DPP-based PV systems. To address the disadvantage of the asynchronous MPPT commonly used in existing DPP topologies, which is inefficient and difficult to extend to large-scale systems, this paper presents a method that makes the application of synchronous MPPT in DPP topology feasible based on a simple and easy partial decoupling method. The innovation of the proposed decoupling method is that the dominant part of the system coupling is obtained by decomposition of the control system, to facilitate more targeted decoupling and reduce the difficulty and complexity of decoupling. Unlike other decoupling methods, the proposed approach does not become more complex with an increase in the size of the system, and thus has good scalability. In addition, the efficiency of MPPT is improved, as synchronous MPPT control can significantly reduce the MPPT time of the PV system. The results of simulations and experiments validate the effectiveness of the proposed decoupling method and the high performance of synchronous MPPT in DPP-based PV systems.

A virtual bus parallel differential power processing configuration for photovoltaic applications

Photovoltaic (PV) systems are often exposed to mismatch caused by partial shading, different mounting angles, dust accumulation, cell degradation, and so on. This paper proposes a novel parallel differential power processing (P-DPP) configuration to minimize mismatch-related losses among PV strings. The proposed configuration, called PV to Virtual Bus P-DPP, uses a virtual bus as an input for all P-DPP converters. Since the virtual bus voltage can be selected lower than the DC Bus voltage, components’ voltage rating can be reduced. An essential feature of the proposed configuration is the ability of the converters to generate both positive and negative output voltage. Therefore, a bidirectional flyback converter connected to a bridgeless converter is proposed as the P-DPP converter. To find the MPP of each PV string, the Perturb and Observe (P&O) algorithm is implemented. Moreover, a proportional-integral feedback controller controls the virtual bus voltage through the central converter. The benefits of the proposed configuration are discussed, and the operation of the proposed structure is further verified through simulations with the software PLECS.

Design and Optimization of Photovoltaic System in Full-Chain Ground-Based Validation System of Space Solar Power Station

In the face of the increasing depletion of non-renewable energy sources and increasingly serious environmental problems, the development of green and environmentally friendly renewable energy sources cannot be delayed. Because of the far-reaching development potential of solar energy, solar power has become an important research object for power development. The available solar energy in space is several times greater than that on Earth. Solar energy from space can be collected by a space solar power station (SSPS) and transmitted to the ground by wireless power transfer. In the full-chain ground-based validation system of SSPS-OMEGA, the spherical concentrator is used, and the light intensity distribution on the solar receiver is non-uniform. The non-uniform light intensity makes the output current of each photovoltaic (PV) cell on the solar receiver greatly different, and causes power losses, known as the mismatch problem. This paper proposes a simple, efficient and easy-to-implement method to optimize the structure of PV arrays to reduce the effect of non-uniform light on the output performance of each PV cell, which is beneficial to the topology of PV arrays and also effectively improves the layout rate. Then, a differential power processing (DPP) converter with a simple structure and easy control is designed to further deal with the power mismatch problem between series-connected PV modules. Finally, a simulation circuit model and a physical hardware model of the differential power processing PV system are built and used in the full-chain ground-based validation system of SSPS-OMEGA. The results demonstrate that the influence of non-uniform lighting on PV cells is effectively reduced, the output power of PV modules connected in series under non-uniform light distribution is substantially increased, and the photoelectric conversion efficiency is significantly improved.

Multiport DC-DC Converter with Differential Power Processing for Fast EV Charging Stations

With the growing interest in owning electric vehicles due to increased environmental awareness and uncertain energy security together with the development of Li-ion batteries, quietness, and trouble-free operation, it is urgent to develop charging stations that are fast enough to supply the vehicles with energy conveniently, as in case of conventional petrol stations. The main reason that hinders the spread of fast charging stations is the installation cost, comprising the infrastructure and converter costs. In this article, a multiport DC-DC converter with differential power processing stages is proposed for Electric Vehicle (EV) fast charging stations, which results in a considerable reduction in the cost of using converters while achieving high efficiency. The proposed topology consists of two paths for the power flow (outer and inner loops) for EV battery charging with main and auxiliary DC-DC converters in the outer loop; all the ports are connected in series with the main supply, where the bulk power is being transferred. The main DC-DC converter injects a series voltage to control the power in the outer loop. The auxiliary DC-DC converters are rated at a fractional power that controls the partial power supplied to each port through the inner loops. Thanks to the fractional power processed by the auxiliary converter with the remaining power fed to the battery through the main converter, the proposed architecture enables simultaneous charging of multiple electric vehicles with better efficiency, lower cost, and the capability of providing a fault tolerance feature. A PWM control scheme for the converters to achieve bi-directional power flow in the partially rated DC-DC converters is discussed for the proposed system. Moreover, a practical down-scaled hardware prototype is designed to validate the functionality, control scheme, and effectiveness of the proposed topology in different case studies being investigated. The efficiency of the proposed converter is compared to the conventional configuration.

Module-to-Panel Modular Differential Power Processing Converter With Isolated DC Bus for Photovoltaic Systems Under Partial Shading

The occurrence of partial shading is known to significantly reduce the energy yield of photovoltaic (PV) panels. Differential power processing (DPP) converters can prevent negative influences of partial shading at a substring level. For PV strings comprising numerous series-connected panels, however, conventional DPP converters face various issues, such as increased converter count, poor extendibility, and cumulative power conversion loss. This article proposes a modular DPP converter with an isolated dc bus for PV strings. The proposed DPP converter is the integration of panel- and module-level DPP converters. Four panels are grouped as a module having a DPP converter, and each DPP converter can handle four panels. PV systems can be scalable with no need to redesign the DPP converter as all modules are connected through the isolated dc bus. The isolated dc bus allows the direct power transfer from unshaded high-voltage modules to shaded low-voltage ones, reducing the cumulative power conversion loss. A field testing for a three-module PV string was performed using a prototype for a four-panel 1-kW module. The experimental results demonstrated 5.6% energy yield enhancement by the proposed DPP converter.

A New Control Approach for Least Processed Power Tracking Under Mismatch Conditions in PV Systems Using Differential Power Processing

A New Control Approach for Least Processed Power Tracking Under Mismatch Conditions in PV Systems Using Differential Power Processing

Differential Power Processing Converter With Active Clamp Structure and Integrated Planar Transformer for Power Generation Optimization of Multiple Photovoltaic Submodules

In recent years, in order to improve the fuel efficiency of electric vehicles, a lot of research has been conducted to adopt photovoltaic (PV) systems to electric vehicles. In addition, various Differential Power Processing (DPP) converters that can mitigate power imbalance among submodules in PV systems are being studied and developed. However, most conventional DPP converters suffer from large volume, low-price competitiveness, and low efficiency. Therefore, in this paper proposes a novel DPP converter. The proposed DPP converter can significantly reduce the volume of converter by integrating multiple transformers into single transformer. Moreover, because of the active clamp structure, it is possible to eliminate secondary side circuits. Furthermore, more than 95% efficiency under 10-60% load and maximum 96.654% efficiency about 20% load were achieved. Thus, the proposed DPP converter can achieve high power density, high price competitiveness, as well as high efficiency. To support the validity of the proposed converter, a prototype of the proposed DPP converter was built, and experiments were proceeded with 8V input and 60W/30V output specifications.

Fault Tolerant Modular Differential Power Processing Converter for Photovoltaic Systems

This paper proposes a fault tolerant modular differential power processing (DPP) converter for photovoltaic (PV) systems under partial shading conditions. The proposed DPP converter can be derived by integrating panel-level and module-level DPP converters, reducing the total switch count, and achieving a simplified circuit. The modular design of the proposed converter allows PV systems to be flexibly scaled up without redesigning converters. Furthermore, series-resonant tanks in the proposed DPP converter exhibit constant-current–constant-voltage characteristics that realize the inherent fault tolerance against short-circuit and open-circuit fault of PV panels. The prototype for a 1.5-kW PV system consisting of two modules, each comprising four panels connected in series, was built and tested. In addition to the fault tolerance, the energy yield enhancement of 19.6% was experimentally demonstrated.

Integrated differential power processing converters for PV systems

Nowadays the growth of Module Integrated Converters (MIC) concept is increasing. This concept was developed for PV applications to improve the efficiency of the converters. In this paper we propose a submodule MPP tracking algorithm to track the maximum power from the partially shaded cells. Generally, PV module have three submodules. Each submodule is formed by series connection of two strings. Here we take a different P&O algorithm for each submodule to track maximum power from the all three submodules. Each submodule will have their own DC-DC converter. In DC stage, DC-DC converters are connected in three configurations to serve sufficient energy to inverter for single phase grid connected systems.

Analysis and Design of Series Voltage Compensator for Differential Power Processing

Differential power processing (DPP) has been proven effective in many applications. This article explores a series voltage compensator (SVC) architecture for voltage regulation of DPP systems. An SVC is connected in series between the input dc bus and the DPP system to compensate for the voltage difference. It only processes a fraction of the overall power. The inclusion of an SVC changes the power flow of the DPP system and changes the loss distribution. We theoretically investigated the SVC power rating and the additional power conversion stress that SVC brings to the DPP converter. Accordingly, we identified the operation range where an SVC is more attractive than a conventional DPP pre-regulation converter that has to process the full power. Our analysis provides insights into system design and control strategy of SVC-DPP topologies. To validate the principles of SVC, a buck SVC is designed and applied to a ten-port DPP converter. The buck SVC can efficiently convert an input voltage ranging from 50 V to 65 V into a regulated 50 V for the DPP system. The size of the SVC is only 20% of the DPP converter, and the peak efficiency of the SVC-DPP system achieves 98.8%.

Classification of Differential Power Processing Architectures Based on VA Area Modeling

This article reviews and classifies the representative types of “differential power processing (DPP)” architectures, focusing on the aspect of how the processed power is reduced with DPP. Comparing with existing review works on this topic, this article provides new viewpoints from three perspectives. First, the differential power <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{{\text {diff}}}$ </tex-math></inline-formula> at both architecture level and converter level is discussed. For the calculation of the total processed power in a power architecture, instead of summing up the output power <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{{\text {out}}}$ </tex-math></inline-formula> delivered by the DPP converters, we account for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{{\text {diff}}}$ </tex-math></inline-formula> inside the DPP converters because direct power exists not only at the architecture level but also at the converter level, and thus, the power processed in a converter may be lower than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{{\text {out}}}$ </tex-math></inline-formula> . Second, the VA area modeling is applied to the DPP architectures to illustrate and visualize the processed power in the power architectures and converters, thus analyzing and comparing them at high level. Finally, the processed power of different DPP architectures is compared quantitatively with statistical analysis for varied operating situations.

Performance Assessment of Mismatch Mitigation Methodologies Using Field Data in Solar Photovoltaic Systems

Partial shading and other non-ideal conditions cause electrical mismatches that reduce the output power generated by a photovoltaic (PV) system. It affects the overall performance and efficiency of PV systems. Therefore, a model is developed in MATLAB, which analyses the performance of the PV systems under real irradiance profiles and temperatures for various available mismatch mitigation methodologies, i.e., bypass diode, DC power optimizer, and differential power processing (DPP). More specifically, this study will help to understand the best mismatch reduction methodologies for a solar PV system under different scenarios. The results also are validated by comparing them with a similar PV system installed in SolarTechLAB, which also operates under the same irradiance and temperature conditions under which these models are tested. This study also presents novel results, covering discussions on the reverse voltage distribution under mismatch scenarios among bypass diode, DC power optimizer, and DPP techniques.