Maximum Power Point Tracking Architecture Research Articles

Nanosatellite electrical power system architectures: Models, simulations, and tests

SummaryThis paper presents four of the most employed nanosatellite's Electrical Power System (EPS) architectures, comparing their efficiency through simulations and experiments. Every circuit architecture has been mathematically modeled in order to discuss the solar panel control technique and the overall architecture efficiency. Solar panels and EPS components have been analytically modeled and tested in order to comprehend their impact on the EPS efficiency. A test stand has been proposed to evaluate the circuits, emulating the solar irradiance and the nanosatellite power consumption. The following electrical power systems have been designed, implemented, and tested: the directly coupled architecture, the very low dropout (VLDO) voltage regulator architecture, the maximum power point tracking (MPPT) with an integrated circuit, and the MPPT architecture with a discrete boost regulator. A case study has been presented, testing all the EPS architectures according to the Floripa‐Sat I (1U CubeSat) power consumption profile. Experiments results have shown that, although the MPPT boost regulator architecture harvest more energy, it is the VLDO architecture that presents the best overall efficiency.

Detection of Typical Defects in Silicon Photovoltaic Modules and Application for Plants with Distributed MPPT Configuration

During their operational life, photovoltaic (PV) modules may exhibit various defects for poor sorting of electrical performance during manufacturing, mishandling during transportation and installation, and severe thermo-mechanical stresses. Electroluminescence testing and infrared thermographic imaging are the most common tests for checking these defects, but they are only economically viable for large PV plants. The defects are also manifested as abnormal electrical properties of the affected PV modules. For defect diagnosis, the appropriate parameters on their I-V curves are open circuit voltage, photo-generated current, series resistance, and the shunt resistance. The health of PV modules can be assessed by calculating these values and comparing them with the reference parameters. If these defects are diagnosed in time, the power loss is avoided and safety hazards are mitigated. This paper first presents a review of common defects in PV modules and then a review of the methods used to find the above-mentioned parameters during the normal PV operation. A simple approach to determine the resistances of the equivalent circuit is discussed. Finally, through a modification in an ordinary maximum power point tracking (MPPT) algorithm, information about the state of health of PV modules is obtained. This method is effective, especially if applied to submodule-integrated MPPT architectures.

Analysis of Power Processing Architectures for Thermoelectric Energy Harvesting

This paper analyzes, from a power processing architecture standpoint, the recovery of thermal energy waste by means of thermoelectric (TE) modules and arrays. The existence, in many industrial scenarios, of stable and often significant temperature gradients enables a number of possibilities for effective processing and recovery of waste heat, which could result in marked economic savings and environmental benefits if adopted on a large scale and systematically embedded into industrial processes. A review of the TE source is provided first, along with an extensive experimental characterization of commercial bismuth-telluride TE cells. Results indicate that maximum power extraction from TE generators can be achieved at a TE efficiency close to optimal, motivating the adoption of maximum power point tracking architectures, traditionally employed in photovoltaic systems, to TE plants as well. Three power processing architectures are then analyzed and compared in terms of their maximum power extraction capabilities and of the efficiency constraint they pose on the power processors. Different from the photovoltaic case, the simple series configuration of TE modules allows to extract most of the available power even in the presence of rather large mismatches among the modules. For even larger mismatch levels, the differential power processing (DPP) concept, already introduced for dc–dc distribution systems and photovoltaic plants, can be successfully adopted to improve power extraction. On the other hand, the module-integrated converter architecture, another well-established solution for photovoltaic sources, is found to be much less indicated for TE generators than the DPP solution. Main conclusions are experimentally validated using a DPP architecture with a two-cell test bed operated at different thermal gradients.

Photovoltaic Systems Reliability Improvement by Real-Time FPGA-Based Switch Failure Diagnosis and Fault-Tolerant DC–DC Converter

The increased penetration of photovoltaic (PV) systems in different applications with critical loads such as in medical applications, industrial control systems, and telecommunications has highlighted pressing needs to address reliability and service continuity. Recently, distributed maximum power point tracking architectures, based on dc–dc converters, are being used increasingly in PV systems. Nevertheless, dc–dc converters are one of the important failure sources in a PV system. Since the semiconductor switches are one of the most critical elements in these converters, a fast switch fault detection method (FDM) is a mandatory step to guarantee the service continuity of these systems. This paper proposes a very fast FDM based on the shape of the inductor current associated to fault-tolerant (FT) operation for boost converter used in PV systems. By implementing fault diagnosis and reconfiguration strategies on a single field-programmable gate array target, both types of switch failure (open- and short-circuit faults) can be detected, identified and handled in real time. The FDM uses the signal provided by the current sensor dedicated to the control of the system. Consequently, no additional sensor is required. The proposed FT topology is based on a redundant switch. The results of hardware-in-the-loop and experimental tests, which all confirm the excellent performances of the proposed approach, are presented and discussed. The obtained results show that a switch fault can be detected in less than one switching period, typically around 100 ms in medium power applications, by the proposed FDM.

Distributed photovoltaic solar system architecture with single‐power inductor single‐power converter and single‐sensor single maximum power point tracking controller

This study presents a distributed photovoltaic (PV) solar system architecture with a single-power inductor, single-power converter and single maximum power point tracking (MPPT) controller that only requires one sensor. This PV architecture is able to perform MPPT for a multichannel distributed PV system at panel level, cell group level and/or single cell level under mismatching and partial shading conditions. The single power stage is a multiple-input single-inductor boost power converter which operates in continuous conduction mode. This work targets the high-cost and high-complexity issues of module integrated converter (MIC) and sub-MIC PV architectures, which affect their practicality in many applications. The concept and operation of the single-power-converter single-controller single-sensor MPPT architecture is presented, analysed and verified by results obtained from a proof-of-concept experimental prototype.

Maximum power point tracking architectures for photovoltaic systems in mismatching conditions: a review

In practical photovoltaic (PV) installations the operating conditions of the panels the PV array is made of are different owing to different factors. Such irregular conditions are known as ‘mismatching conditions’ and produce multiple maxima in the power-voltage curves of any PV array. The traditional maximum power point tracking (MPPT) techniques are able to track one of those maxima, but they cannot guarantee the extraction of the maximum power the PV array would be able to deliver. To overcome this problem, many techniques have been presented in the literature: they use one converter for the entire array (centralised MPPT), one converter for each part of the array (distributed MPPT) or they reconfigure the PV array (RMPPT). This paper presents the general architectures used by 61 different MPPT techniques, by discussing their main advantages and disadvantages, in order to give to the reader a comprehensive view of both the control strategies and the architectures for extracting the maximum power from a mismatched PV field. Moreover, the widely adopted techniques for each hardware structure are presented in a structured and compact way, thus providing to the reader some guidelines regarding the technique's operation principle and hardware requirements.

A two-steps algorithm improving the P&O steady state MPPT efficiency

A key point in the control of photovoltaic (PV) systems is the design of the maximum power point tracking (MPPT) algorithm. Although a huge number of approaches has been proposed in literature, the methods based on the perturb and observe (P&O) technique are the most widely employed in commercial products. The reason is in the fact that P&O can be implemented in cheap digital devices by assuring high robustness and a good MPPT efficiency. The low hardware resources required by the P&O algorithm are especially useful in distributed MPPT architectures, where the cost makes the difference. The performances of the P&O algorithm implemented in a digital device are affected by the quantization effect and numerical approximations. In this paper the basic P&O algorithm is suitably improved in order to compensate for these effects. A design recipe for choosing the best values of the P&O parameters is also given. The conclusions of the theoretical analysis are validated through simulations and experiments.