Modeling and control of zero-sequence current in parallel multi-phase converters

Ye, Z.; Boroyevich, Dushan; Lee, F.C.

doi:10.1109/pesc.2000.879899

Cited by 31 publications

(3 citation statements)

References 22 publications

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“…Some studies have proposed control techniques to reduce the circulating currents [21][22][23][24][25][26], but the origin and the nature of the problem have not been analyzed in detail in these works. Reference [27] studied the circulating currents produced by phase shifting between the pulse with modulation (PWM) carrier signals of two inverters connected in parallel.…”

Section: The Problem Of Circulating Currents and The Main Contributio...mentioning

confidence: 99%

Experimental Study of the Parameter Mismatch Effects on the Low Frequency Circulating Currents of Parallel Three Phase Inverters

Liberos,

González-Medina,

Patrao

et al. 2023

Eng

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When converters are connected in parallel, a system with some benefits, including modularity and redundancy, is obtained. However, in these circumstances, circulating currents can appear that produce some adverse effects. In this work, a study of the low-frequency circulating currents that appear in three-phase inverters connected in parallel is performed. The study is focused on the effects produced by the parameter mismatch, namely inductance mismatches, power imbalance, and the use of different pulse with modulation (PWM) techniques. The nature of the circulating current produced by each of these factors were analyzed separately. Both simulation and experimental results are shown, which were obtained using a three-phase 10-kW prototype composed of two 5-kW inverters connected in parallel.

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Section: The Problem Of Circulating Currents and The Main Contributio...mentioning

confidence: 99%

Experimental Study of the Parameter Mismatch Effects on the Low Frequency Circulating Currents of Parallel Three Phase Inverters

Liberos,

González-Medina,

Patrao

et al. 2023

Eng

View full text Add to dashboard Cite

show abstract

“…One of the simplest methods to eliminate circulating currents uses transformers to electrically isolate the parallel connected modules. This method leads to an expensive and bulky system, with control methods not requiring extra hardware being preferred [7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

A Control Scheme to Suppress Circulating Currents in Parallel-Connected Three-Phase Inverters

et al. 2022

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The parallel operation of inverters has many benefits, such as modularity and redundancy. However, the parallel connection of inverters produces circulating currents that may result in malfunctions of the system. In this work, a control technique for the elimination of the low-frequency components of the circulating currents in grid-connected inverters is presented. The proposed control structure contains n-1 zero-sequence control loops, with n being the number of inverters connected in parallel. Simulation and experimental results have been carried out on a prototype composed of two 5 kW inverters connected in parallel. The results have been obtained by considering the following mismatches between both inverters: inductance values of the grid filters, unbalance of the delivered power, and the use of different modulation techniques.

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“…In parallel operation, the converters are usually designed individually, but when they operate in parallel, a zero-sequence circulating current that can produce malfunctions in the system appears [11]. To overcome this problem, in [12][13][14], it was proposed the use of isolating transformers as in Figure 1c,d, but therefore an expensive and bulky system results. In other works [15,16], the n parallel modules are treated as only one by considering an equivalent single converter that has as many legs as the number of legs of each module multiplied by n. Nevertheless, this approach doesn't allow modular design and has a great degree of complexity, so that it is only suitable for low values of n.…”

Section: Introductionmentioning

confidence: 99%

Modelling and Control of Parallel-Connected Transformerless Inverters for Large Photovoltaic Farms

et al. 2017

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This paper presents a control structure for transformerless photovoltaic inverters connected in parallel to manage photovoltaic fields in the MW range. Large photovoltaic farms are usually divided into several photovoltaic fields, each one of them managed by a centralized high power inverter. The current tendency to build up centralized inverters in the MW range is the use of several transformerless inverters connected in parallel, a topology that provokes the appearance of significant zero-sequence circulating currents among inverters. To eliminate this inconvenience, this paper proposes a control structure that avoids the appearance of circulating currents by controlling the zero-sequence component of the inverters. A second contribution of the paper is the development of a model of n parallel-connected inverters. To validate the concept, the proposed control structure has been applied to a photovoltaic field of 2 MW managed by four 500 kW photovoltaic inverters connected in parallel.

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Modeling and control of zero-sequence current in parallel multi-phase converters

Cited by 31 publications

References 22 publications

Experimental Study of the Parameter Mismatch Effects on the Low Frequency Circulating Currents of Parallel Three Phase Inverters

Experimental Study of the Parameter Mismatch Effects on the Low Frequency Circulating Currents of Parallel Three Phase Inverters

A Control Scheme to Suppress Circulating Currents in Parallel-Connected Three-Phase Inverters

Modelling and Control of Parallel-Connected Transformerless Inverters for Large Photovoltaic Farms

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