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This article presents a cell-level differential power processing IC to maximize the power yield under partial shading and mismatch condition in series-connected single junction photovoltaic (PV) cells. A 3-MHz bidirectional buck–boost converter is employed to realize voltage equalization technique forcing the PV cells to constantly operate close to their maximum power points. A novel and simple low-power low-area analog control circuit is proposed to maintain the high system efficiency at low and high levels of mismatch by obviating the need for power hungry blocks such as analog to digital converters, digital to analog converters, op-amps, saw-tooth generator, and regulators. The voltage of adjacent PV cells is used to drive the high-side switches through bootstrap supplies eliminating the need for voltage regulators. The performance of the proposed IC, fabricated in 130 nm CMOS process, is validated through simulation and experimental results. The converter is capable of processing mismatch currents up to 4 A while the control circuitry consumes less than 40 mW and a system efficiency above 95% is achieved. [ABSTRACT FROM AUTHOR]

The number of data centers worldwide has been growing exponentially to serve a multitude of aspects of modern life. The major challenges that face data centers operators are the rising electricity bills, growing carbon footprints, and unexpected power outages. An effective approach to tackle such problems is to investigate the implementation of efficient power supplies that offers the rack voltage levels required to power servers. Recently, the differential power processing (DPP) concept proved to potentially offer less number of cascaded stepping down stages by connecting the servers in series and introducing a DPP converter to supply or withdraw current mismatch in the series connection. DPP system can replace the conventional two-stage power electronics converter with an efficiently designed converter. Thus, the series stacking power delivery architecture is proposed with efficient Gallium Nitride (GaN) based power electronics converters to reduce the system size and losses. The introduced review in this paper aims to give the reader a comprehensive understanding of DPP implementation for data centers in terms of the possible series stacking architecture, converter types and switch types. The advantages and disadvantages of each architecture are discussed along with the most commonly employed DPP converters in various applications. Further investigation on the cost-effectiveness and commercialization of GaN-based series stacking architecture still needs further investigation and deployment.

Differential power processing (DPP) is regarded as a promising architecture in solving mismatching issues among photovoltaic (PV) submodules. Although conventional total-minimum-power-point (TMPP)-based real-time optimization algorithm by using the distributed submodule-level maximum power point tracking and simultaneously the centralized total-minimum-power tracking shows effectiveness in maximizing the power yield. However, uneven power stress among DPP converters, large oscillations, high additional cost for communication among DPP converters, and complicated implementation hinder the practical application. This article proposed a low-complexity power balancing point-based optimization algorithm to reduce the system cost and size, improve the system efficiency, and realize the standardized modular design for DPP converters. Furthermore, simple submodule-level voltage equalization control is implemented to eliminate expensive communication and relieve the control complexity while guaranteeing high maximum-power-point efficiency. The proposed algorithm can reduce the power rating of DPP converters compared with conventional TMPP-based control, which is beneficial to the improvement of system cost, reliability, and lifetime. Both simulation and experimental results under various scenarios are provided to validate the advantages of the proposed algorithm. [ABSTRACT FROM AUTHOR]

The number of data centers worldwide has been growing exponentially to serve a multitude of aspects of modern life. The major challenges that face data centers operators are the rising electricity bills, growing carbon footprints, and unexpected power outages. An effective approach to tackle such problems is to investigate the implementation of efficient power supplies that offers the rack voltage levels required to power servers. Recently, the differential power processing (DPP) concept proved to potentially offer less number of cascaded stepping down stages by connecting the servers in series and introducing a DPP converter to supply or withdraw current mismatch in the series connection. DPP system can replace the conventional two-stage power electronics converter with an efficiently designed converter. Thus, the series stacking power delivery architecture is proposed with efficient Gallium Nitride (GaN) based power electronics converters to reduce the system size and losses. The introduced review in this paper aims to give the reader a comprehensive understanding of DPP implementation for data centers in terms of the possible series stacking architecture, converter types and switch types. The advantages and disadvantages of each architecture are discussed along with the most commonly employed DPP converters in various applications. Further investigation on the cost-effectiveness and commercialization of GaN-based series stacking architecture still needs further investigation and deployment. [ABSTRACT FROM AUTHOR]

Differential power processing (DPP) systems are a promising architecture for future photovoltaic (PV) power systems that achieve high system efficiency through processing a faction of the full PV power, while achieving distributed local maximum power point tracking (MPPT). In the PV-to-bus DPP architecture, the power processed through the DPP converters depends on the string current, which must be controlled to minimize the power processed through the DPP converters. A real-time least power point tracking (LPPT) method is proposed to minimize power stress on PV DPP converters. Mathematical analysis shows the uniqueness of the least power point for the total power processed through the system. The perturb-and-observe LPPT method is presented that enables the DPP converters to maintain optimal operating conditions, while reducing the total power loss and converter stress. This work validates through simulation and experimentation that LPPT in the string-level converter successfully operates with MPPT in the DPP converters to maximize output power for the PV-to-bus architecture. Hardware prototypes were developed and tested at 140 and 300 W, and the LPPT control algorithm showed effective operation under steady-state operation and an irradiance step change. Peak system efficiency achieved with a 140-W prototype DPP system employing LPPT is 95.7%. [ABSTRACT FROM PUBLISHER]

Conventional energy conversion architectures in photovoltaic (PV) systems are often forced to tradeoff conversion efficiency and power production. This paper introduces an energy conversion approach that enables each PV element to operate at its maximum power point (MPP) while processing only a small fraction of the total power produced. This is accomplished by providing only the mismatch in the MPP current of a set of series-connected PV elements. Differential power processing increases overall conversion efficiency and overcomes the challenges associated with unmatched MPPs (due to partial shading, damage, manufacturing tolerances, etc.). Several differential power processing architectures are analyzed and compared with Monte Carlo simulations. Local control of the differential converters enables distributed protection and monitoring. Reliability analysis shows significantly increased overall system reliability. Simulation and experimental results are included to demonstrate the benefits of this approach at both the panel and subpanel level. [ABSTRACT FROM AUTHOR]