Flyback inverter controlled by sensorless current MPPT for photovoltaic power system
TL;DR: The paper shows that the application of this novel sensorless current flyback inverter to an MPPT-operated PV system exhibits satisfactory MPPT performance similar to the one exhibited by the system with a dc current sensor as well.
Abstract: This paper presents a flyback inverter controlled by sensorless current maximum power point tracking (MPPT) for a small photovoltaic (PV) power system. Although the proposed system has small output power such as 300 W, a few sets of small PV power systems can be easily connected in parallel to yield higher output power. When a PV power system is constructed with a number of small power systems, the total system cost will increase and will be a matter of concern. To overcome this difficulty, this paper proposes a PV system that uses no expensive dc current sensor but utilizes the method of estimating the PV current from the PV voltage. The paper shows that the application of this novel sensorless current flyback inverter to an MPPT-operated PV system exhibits satisfactory MPPT performance similar to the one exhibited by the system with a dc current sensor as well. This paper also deals with the design method and the operation of the unique flyback inverter with center-tapped secondary winding.
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TL;DR: The many different techniques for maximum power point tracking of photovoltaic (PV) arrays are discussed in this paper, and at least 19 distinct methods have been introduced in the literature, with many variations on implementation.
Abstract: The many different techniques for maximum power point tracking of photovoltaic (PV) arrays are discussed. The techniques are taken from the literature dating back to the earliest methods. It is shown that at least 19 distinct methods have been introduced in the literature, with many variations on implementation. This paper should serve as a convenient reference for future work in PV power generation.
5,022 citations
Cites background or methods from "Flyback inverter controlled by sens..."
...Among all the papers we gathered, much focus has been on hill climbing [1]–[8], and perturb and observe (P&O) [9]–[25] methods....
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...In [25], the PV array current from the PV array voltage is estimated, eliminating the need for a current sensor....
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...MPPT methods that require only one sensor or that can estimate the current from the voltage as in [25]....
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TL;DR: In this paper, a topology study of the PV MICs in the power range below 500 W and covers most topologies recently proposed for MIC applications is presented, where the MIC topologies are classified into three different arrangements based on the dc link configurations.
Abstract: The annual world photovoltaic (PV) cell/module production is growing at almost an exponential rate and has reached 1727 MW in 2005. Building integrated PV (BIPV) projects are emerging as the strongest part of the PV market and grid interactive inverters are a key component in determining the total system cost. Module integrated converter (MIC) technology has become a global trend in grid interactive PV applications and may assist in driving down the balance of system costs to secure an improved total system cost. This paper concentrates on the topology study of the PV MICs in the power range below 500 W and covers most topologies recently proposed for MIC applications. The MIC topologies are classified into three different arrangements based on the dc link configurations. A systematic discussion is also provided at the end of the paper that focuses on the major advantages and disadvantages of each MIC arrangement. These are considered in detail and will provide a useful framework and point of reference for the next generation MIC designs and applications.
1,158 citations
Cites background from "Flyback inverter controlled by sens..."
...A similar topology is also proposed in [77], where the polarities of the dc voltage source and the primary side MOSFET are reversed....
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TL;DR: A novel algorithm to track the global power peak under partially shaded conditions and a feedforward control scheme for operating the DC-DC converter is proposed, which uses the reference voltage information from the tracking algorithm to shift the operation toward the MPP.
Abstract: Current-voltage and power-voltage characteristics of large photovoltaic (PV) arrays under partially shaded conditions are characterized by multiple steps and peaks. This makes the tracking of the actual maximum power point (MPP) [global peak (GP)] a difficult task. In addition, most of the existing schemes are unable to extract maximum power from the PV array under these conditions. This paper proposes a novel algorithm to track the global power peak under partially shaded conditions. The formulation of the algorithm is based on several critical observations made out of an extensive study of the PV characteristics and the behavior of the global and local peaks under partially shaded conditions. The proposed algorithm works in conjunction with a DC-DC converter to track the GP. In order to accelerate the tracking speed, a feedforward control scheme for operating the DC-DC converter is also proposed, which uses the reference voltage information from the tracking algorithm to shift the operation toward the MPP. The tracking time with this controller is about one-tenth as compared to a conventional controller. All the observations and conclusions, including simulation and experimental results, are presented.
978 citations
TL;DR: In this article, a design example is presented by experimental implementation of the proposed technique and practical results for the implemented setup at different irradiance levels are illustrated to validate the proposed scheme.
Abstract: Solar photovoltaic (PV) energy has witnessed double-digit growth in the past decade. The penetration of PV systems as distributed generators in low-voltage grids has also seen significant attention. In addition, the need for higher overall grid efficiency and reliability has boosted the interest in the microgrid concept. High-efficiency PV-based microgrids require maximum power point tracking (MPPT) controllers to maximize the harvested energy due to the nonlinearity in PV module characteristics. Perturb and observe (PO second, no steady-state oscillations around the MPP; and lastly, no need for predefined system-dependent constants, hence provides a generic design core. A design example is presented by experimental implementation of the proposed technique. Practical results for the implemented setup at different irradiance levels are illustrated to validate the proposed technique.
774 citations
TL;DR: The goal of this paper is to provide an overview of the open problems related to PV power processing systems and to focus the attention of researchers and industries on present and future challenges in this field.
Abstract: Power processing systems will be a key factor of future photovoltaic (PV) applications. They will play a central role in transferring, to the load and/or to the grid, the electric power produced by the high-efficiency PV cells of the next generation. In order to come up the expectations related to the use of solar energy for producing electrical energy, such systems must ensure high efficiency, modularity, and, particularly, high reliability. The goal of this paper is to provide an overview of the open problems related to PV power processing systems and to focus the attention of researchers and industries on present and future challenges in this field.
559 citations
References
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TL;DR: A simple method of tracking the maximum power points (MPPs) and forcing the system to operate close to these points is presented, and the principle of energy conservation is used to derive the large- and small-signal model and transfer function.
Abstract: Photovoltaic systems normally use a maximum power point tracking (MPPT) technique to continuously deliver the highest possible power to the load when variations in the insulation and temperature occur. It overcomes the problem of mismatch between the solar arrays and the given load. A simple method of tracking the maximum power points (MPPs) and forcing the system to operate close to these points is presented. The principle of energy conservation is used to derive the large- and small-signal model and transfer function. By using the proposed model, the drawbacks of the state-space-averaging method can be overcome. The TI320C25 digital signal processor (DSP) was used to implement the proposed MPPT controller, which controls the DC/DC converter in the photovoltaic system. Simulations and experimental results show excellent performance.
746 citations
TL;DR: In this paper, a microcomputer-based control of a residential photovoltaic power conditioning system is described, which is responsible for array current feedback control, maximum power tracking control, array safe zone steering control, phase-locked reference wave synthesis, sequencing control, and some diagnostics.
Abstract: Microcomputer-based control of a residential photovoltaic power conditioning system is described. The microcomputer is responsible for array current feedback control, maximum power tracking control, array safe zone steering control, phase-locked reference wave synthesis, sequencing control, and some diagnostics. The control functions are implemented using Intel 8751 single-chip microcomputer-based hardware and software. The controller has been tested in the laboratory with the prototype power conditioner and shows excellent performance.
339 citations
"Flyback inverter controlled by sens..." refers methods in this paper
...The perturbation-and-observation method is often used for the MPPT in many PV systems [15], [16]....
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07 Nov 2002
TL;DR: In this paper, a flyback-type utility interactive inverter is proposed for photovoltaic (PV) power generation systems, which allows stable AC current injection into the utility line without AC current sharing control.
Abstract: In recent years, interest in natural energy has grown because of increased environmental concerns. Many kinds of inverter circuits and their control schemes for photovoltaic (PV) power generation systems have been studied. In a conventional system, the PV array in which many PV modules are connected in series is used to obtain sufficient DC-bus voltage for generating an AC utility line voltage from an inverter circuit. However, the total power generation of the PV array is sometimes decreased remarkably when a few modules are partially covered by shadows, thereby decreasing its inherent current generation, and preventing the generation current attaining its maximum value on the array. To overcome this drawback, an AC module strategy has been proposed. In this system, a small power DC-AC utility interactive inverter is mounted on each PV module individually. This inverter operates so as to generate the maximum power from its corresponding PV module. This paper proposes a novel flyback-type utility interactive inverter circuit suitable for AC module systems. The features of the proposed system are that it: (1) is small in volume and lightweight; (2) allows stable AC current injection into the utility line; (3) enables the stable parallel operation without AC current sharing control; and (4) enables the capacitance of the DC capacitor to be small. The effectiveness of the proposed system is clarified through simulation and experiments.
196 citations
Additional excerpts
...already presented in the literature [12]–[14]; however, since the method still does not have widespread familiarity, the features are summarized here as follows....
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01 Nov 2000
TL;DR: In this paper, a perturbation and observation method with a capacitor identifier is presented for maximum power point tracking (MPPT) in a photovoltaic power system, where the model reference adaptive system is adapted to identify the capacitor, so the capacitance can be accurately estimated and the variation of the duty ratio can be corrected by the estimated value.
Abstract: A perturbation and observation method with a capacitor identifier is presented for maximum power point tracking (MPPT) in a photovoltaic power system. Usually, by increasing or decreasing the duty ratio of on-state of switching device, the maximum power point is tracked. The variation of duty ratio is determined by considering its circuit parameters. However, it is known that actual capacitance of an electrolytic capacitor in parallel with the photovoltaic array has 50% tolerance of its nominal value. If the variation of duty ratio is determined based on its nominal value, the performance of the MPPT is degraded. Thus, we must change the variation of the duty ratio accordingly, based on its actual value. In the system presented, the model reference adaptive system is adapted to identify the capacitor, so the capacitance can be accurately estimated and the variation of the duty ratio can be corrected by the estimated value. As a result, the high performance of the MPPT may be obtained. Experimental results are presented using a proposed power inverter using buck-boost chopper circuits.
136 citations
01 Mar 1996
TL;DR: In this article, the harmonic distortion of the output current waveform of the inverter fed to the grid is within the stipulated limits laid down by the utility companies, and the applicability of the design is verified.
Abstract: Detailed analysis and simulation results of a novel solar photovoltaic inverter configuration interconnected to the grid are presented. From the simulation results it is confirmed that the harmonic distortion of the output current waveform of the inverter fed to the grid is within the stipulated limits laid down by the utility companies. Typical hardware aspects are also discussed in detail and the applicability of the design is verified.
119 citations