SPV Power Optimization Using Half Bridge Inverter and Voltage Multiplier
01 Oct 2019-pp 2593-2598
TL;DR: A circuit topology working on differential power processing (DPP) concept has been analysed and an equalizer circuit which injects extra current in parallel with the shaded modules is employed.
Abstract: In a high power, grid connected photovoltaic (PV) array system a large number of PV modules need to be connected in series and parallel to get the required power level and dc bus voltage of around 700 – 760 V. Commercially available PV modules are provided with bypass diodes across each string of about 20-cells in, say, a 60-cells module. Among the series connected modules, some may get partially shaded mainly because of dust particles, clouds, bird droppings etc. The partially shaded module(s) or string(s) may get bypassed through the bypass diode(s), especially at higher output current. This may also cause multiple power peaks and may pose difficulty for the maximum power point tracking (MPPT) algorithm. As a result the overall power yield of the PV array may reduce. In this paper a circuit topology working on differential power processing (DPP) concept has been analysed. This topology employs an equalizer circuit which injects extra current in parallel with the shaded modules. This allows the series connected modules to operate at their individual maximum power points and the PV string sees a single peak in the power versus voltage curve. The present equalizer circuit topology has some additional advantages over various other equalizer topology reported in literature. Equalizer modeling equations in different modes of operation are reproduced and working of converter circuit is described based on derived dc equivalent circuit. The transformer turn ratio effect of the implemented converter topology is analyzed and discussed. Matlab simulation and experimental results show the efficacy of the employed converter.
Citations
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Patent•
21 Jun 1994
TL;DR: In this article, the battery charger 10 is recharging the reusable battery and includes a voltage source and, lossless shunt configuration in order to produce a battery charger that can charge the battery a predetermined number of times.
Abstract: The battery charger 10 is recharging the reusable battery The charger includes a voltage source and, lossless shunt configuration in order to be produced in order to charge the battery a predetermined number. Charger 10 may be current limited voltage source, which is controlled by the state of charge of the battery voltage or to be recharged. Lossless shunt pair of transistors for each pair of batteries (Q Same, controlling each of the transistors opposite to the two phases (Φ1 and Φ2) an oscillator (14 and 204), the first phase the charge for a predetermined supplying a charge to the battery and a second phase during which the so equalized between batteries pairs It is used to. Equalization is continued until one not overcharge the battery reaches full charge before the two batteries.
43 citations
14 Dec 2022
TL;DR: In this paper , a novel Z-reconfiguration scheme based on physical rearrangement of the panels of the array is proposed with the same electrical connections of panels as TCT.
Abstract: Due to partial shading, the efficiency of photovoltaic system is reduced drastically. This is due to the fact that solar panels in the solar PV array get various level of insolation. The power-voltage plot of an array under partial shading has several local maxima and one global maxima which appear as multiple peaks. Even though totally cross-tied (TCT) connection increases the maximum power yield, it can still be further enhanced. In this paper, a novel Z-reconfiguration scheme based on physical rearrangement of the panels of the array is proposed with the same electrical connections of the panels as TCT. The results obtained from the proposed configuration are verified under different shading conditions and also compared with existing configurations such as TCT and twisted two-step technique (TTST).
14 Dec 2022
TL;DR: In this paper , a novel Z-reconfiguration scheme based on physical rearrangement of the panels of the array is proposed with the same electrical connections of panels as TCT.
Abstract: Due to partial shading, the efficiency of photovoltaic system is reduced drastically. This is due to the fact that solar panels in the solar PV array get various level of insolation. The power-voltage plot of an array under partial shading has several local maxima and one global maxima which appear as multiple peaks. Even though totally cross-tied (TCT) connection increases the maximum power yield, it can still be further enhanced. In this paper, a novel Z-reconfiguration scheme based on physical rearrangement of the panels of the array is proposed with the same electrical connections of the panels as TCT. The results obtained from the proposed configuration are verified under different shading conditions and also compared with existing configurations such as TCT and twisted two-step technique (TTST).
References
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TL;DR: In this paper, the authors proposed an alternative topology of nonisolated per-panel dc-dc converters connected in series to create a high voltage string connected to a simplified dc-ac inverter.
Abstract: New residential scale photovoltaic (PV) arrays are commonly connected to the grid by a single dc-ac inverter connected to a series string of pv panels, or many small dc-ac inverters which connect one or two panels directly to the ac grid. This paper proposes an alternative topology of nonisolated per-panel dc-dc converters connected in series to create a high voltage string connected to a simplified dc-ac inverter. This offers the advantages of a "converter-per-panel" approach without the cost or efficiency penalties of individual dc-ac grid connected inverters. Buck, boost, buck-boost, and Cu/spl acute/k converters are considered as possible dc-dc converters that can be cascaded. Matlab simulations are used to compare the efficiency of each topology as well as evaluating the benefits of increasing cost and complexity. The buck and then boost converters are shown to be the most efficient topologies for a given cost, with the buck best suited for long strings and the boost for short strings. While flexible in voltage ranges, buck-boost, and Cu/spl acute/k converters are always at an efficiency or alternatively cost disadvantage.
989 citations
TL;DR: In this paper, 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 is presented.
Abstract: 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.
411 citations
"SPV Power Optimization Using Half B..." refers methods in this paper
...To reduce the conversion losses various DPP converters [2], [3] have been proposed....
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Patent•
21 Jun 1993
TL;DR: In this paper, a battery charger is described for recharging reusable batteries in a manner that prevents overcharging of the same, including a voltage source and non-dissipative shunt arrangement that can be customized to charge any number of batteries.
Abstract: A battery charger is disclosed for recharging reusable batteries in a manner that prevents overcharging of the same. The charger includes a voltage source and non-dissipative shunt arrangement that can be customized to charge any number of batteries. The charger may be a current limiting power supply that is controlled by the voltage or charge state of the batteries being recharged. The non-dissipative shunt includes a pair of transistors for each pair of batteries and an inductor placed one end between the battery pair and another end between the transistor pair. An oscillator, having two phases of equal, but opposite phase, is used to control each transistor to apply charge to a given battery during one phase and then to allow the charge to equalize between the battery pair during the second phase. The equalization is continued until both batteries reach a full charge without overcharging any one battery.
128 citations
TL;DR: In this paper, a double-switch cell voltage equalizer using a parallel-resonant-inverter (PRI) or series-parallel-reonant inverter (SPRI) and voltage multiplier is proposed for series-connected supercapacitors (SCs) such as electric double-layer capacitors (EDLCs) and lithium-ion capacitors.
Abstract: A double-switch cell voltage equalizer using a parallel-resonant-inverter (PRI) or series-parallel-resonant inverter (SPRI) and voltage multiplier is proposed for series-connected supercapacitors (SCs), such as electric double-layer capacitors (EDLCs) and lithium-ion capacitors. The double-switch operation without the need for a multiwinding transformer offers simpler circuitry as well as better modularity than conventional equalizers requiring multiple switches and/or a multiwinding transformer. Furthermore, the inherent constant current characteristic of the PRI/SPRI at a fixed frequency, not only removes the need for feedback control to limit currents under desired levels but the proposed equalizer can also operate safely, even when some cell voltage is 0 V. Detailed operation analyses were separately performed for the voltage multiplier and PRI/SPRI, and a dc equivalent circuit for the proposed equalizer was mathematically derived. A 10-W prototype for 12 cells connected in series was built, and an experimental equalization test was performed for EDLCs from an initially voltage imbalanced condition. Voltage imbalance of the series-connected EDLCs was successfully eliminated by the equalizer, demonstrating the equalization performance of the proposed equalizer.
89 citations
"SPV Power Optimization Using Half B..." refers background in this paper
...In literature many inverter circuits [5]– [7], [10]–[12] based on forward-fly-back converter [6], LLC resonant [4], and half bridge inverter [5] have been proposed....
[...]
TL;DR: In this article, a two-switch voltage equalizer using an LLC resonant inverter and voltage multiplier is proposed to prevent negative influences of partial shading, such as significant reduction in power generation and the occurrence of multiple maximum power points (MPPs), including local and global MPPs, that hinders and confuses MPP tracking algorithms to operate properly.
Abstract: Various kinds of differential power processing converters and voltage equalizers have been proposed for series-connected photovoltaic (PV) modules to prevent negative influences of partial shading, such as significant reduction in power generation and the occurrence of multiple maximum power points (MPPs), including local and global MPPs, that hinders and confuses MPP tracking algorithms to operate properly. However, since conventional topologies are based on multiple individual dc–dc converters, the required switch count increases proportionally to the number of modules connected in series, increasing the complexity. A two-switch voltage equalizer using an LLC resonant inverter and voltage multiplier is proposed in this paper. The circuitry can be dramatically simplified compared with conventional topologies due to the two-switch configuration. Detailed operation analyses for the LLC resonant inverter and voltage multiplier are separately performed. Experimental equalization tests emulating partially shaded conditions were performed for four PV modules connected in series. With the proposed voltage equalizer, local MPPs successfully disappeared, and extractable maximum power increased compared with those without equalization, demonstrating the effectiveness and performance of the proposed voltage equalizer.
86 citations
"SPV Power Optimization Using Half B..." refers background in this paper
...In literature many inverter circuits [5]– [7], [10]–[12] based on forward-fly-back converter [6], LLC resonant [4], and half bridge inverter [5] have been proposed....
[...]