Modulation Strategy for Multiphase Neutral-Point-Clamped Converters

López, Iraide; Ceballos, Salvador; Pou, Josep; Zaragoza, Jordi; Andreu, Jon; Kortabarria, Iñigo; Agelidis, Vassilios G.

doi:10.1109/tpel.2015.2416911

Cited by 105 publications

(112 citation statements)

References 30 publications

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“…These equations correspond to the well-known fact that the homopolar component provides an associated degree of freedom [15][16][17]. Equations (6)- (8) .…”

Section: Description Of the Methodsmentioning

confidence: 99%

A new modulation method for multilevel converters

Gordillo

2016

2016 18th European Conference on Power Electronics and Applications (EPE'16 ECCE Europe)

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AcknowledgmentsThe author would like to thank Profs. Juan M. Carrasco and E. Galván for their valuable comments and suggestions during fruitful discussions. This work has been funded under grant MINECO-FEDER DPI2013-41891-R. AbstractThis paper presents a simple method for modulation in multilevel converters, which is hardly affected with the number of levels. The method is based on a simple graph, whose x-axis is directly related to the extra degree of freedom associated with component γ (in the αβγ reference frame) of the desired reference vector. In the y-axis, the different possibilities for the phase averaged references are plotted. In this way, the degree of freedom is more explicit than in Space Vector Modulation (SVM) and it can be the basis of new algorithms to pursue additional control objectives such as voltage balancing or commonmode reduction, among others. A comparison with SVM based on examples is included, showing the benefits of the proposed modulation strategy.

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“…These equations correspond to the well-known fact that the homopolar component provides an associated degree of freedom [15][16][17]. Equations (6)- (8) .…”

Section: Description Of the Methodsmentioning

confidence: 99%

A new modulation method for multilevel converters

Gordillo

2016

2016 18th European Conference on Power Electronics and Applications (EPE'16 ECCE Europe)

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“…In addition, the dynamics of these methods are usually slow and they are barely able to reduce the amplitude of the low-frequency NP voltage oscillations. A few specific CBPWM methods for multiphase NPC converters have also been developed recently [42]- [44]. These methods are able to cancel completely the low-frequency NP voltage oscillations and regulate the NP voltage in multiphase NPC converters but they increase the power losses of the converter and degrade the quality of the output voltages.…”

Section: Introductionmentioning

confidence: 99%

Generalized PWM-Based Method for Multiphase Neutral-Point-Clamped Converters With Capacitor Voltage Balance Capability

López

Ceballos

Pou

et al. 2017

IEEE Trans. Power Electron.

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This paper presents a generalized PWM-based control algorithm for multiphase neutral-point-clamped (NPC) converters. The proposed algorithm provides a zero-sequence to be added to the reference voltages that contributes to improve the performance of the converter by: i) regulating the neutral-point (NP) current to eliminate/attenuate the low-frequency NP voltage ripples, ii) reducing the switching losses of the power semiconductors and iii) maximizing the range of modulation indices for linear operation mode. The control method is formulated following a carrier-based PWM approach. Hence, dealing with complex space-vector diagrams to solve the modulation problem for multiphase converters is avoided. The recursive approach means that it can be easily extended to n-phase converters without increasing the complexity and computational burden, making it especially attractive for digital implementation. The proposed method allows regulating the NP voltage without the need for external controllers; therefore, no parameter tuning is required. The algorithm has been tested in a four-leg NPC converter prototype performing as a three-and four-phase system and operating with balanced and unbalanced loads. Index TermsCarrier-based pulse-width modulation, multiphase multilevel converter, neutral-point-clamped converter, capacitor voltage balance.

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“…One of the solutions to meet those requirements is using multi-level converters [5][6][7]. Three-level NPC converters, due to their relatively low costs, simple structure and uncomplicated DC link voltage balancing methods [8], [9], appear to be the most commonly used [10]. Three-level converters offer great advantages as compared with typical two-level converters.…”

Section: Introductionmentioning

confidence: 99%

Predictive and look-up table control methods of a three-level AC-DC converter under distorted grid voltage

Falkowski¹,

Kulikowski²,

Grodzki³

2017

Bulletin of the Polish Academy of Sciences Technical Sciences

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Abstract. Power electronic three-level AC-DC converters connecting a utility grid with DC supplies are widely used in renewable energy sources. For such distributed systems, the quality of energy is very important. Hence, control algorithms of an AC-DC converter have to provide not only a sinusoidal shape of grid current, but also stable operation during transient states in the grid, e.g. voltage dips or voltage unbalance. This paper deals with the problem of robustness of AC-DC control methods under disturbed grid voltage. Three modern predictive control algorithms are presented and investigated under grid voltage distortions. Experimental results from a laboratory test setup illustrating properties of the described methods are shown. Conventional linear control methods, such as VOC and DPC-SVM, are designed to control only the fundamental component of current. In order to fulfill GCRs and achieve robustness under grid voltage distortion, these linear methods need additional compensation algorithms that, in turn, increase their complexity [16]. There are many publications concerning improvements of the classical control methods in order to ensure proper converter operation under grid voltage distortions [17][18][19]. However, there are only few that relate to non-linear or predictive control methods of AC-DC converters under grid voltage distortion [20,21]. This paper presents three modern non-linear control algorithms. The first one, direct power control three levels three areas (DPC-3L-3A) [13], is an extended version of the look-up table DPC with new optimal error plane distribution as well as with transfer of the error vector into a new coordinate system. Selection of the converter voltage vector is based on the error vector angle, which makes it possible to eliminate the inconvenience of using comparators. The second method presented here, called predictive control of current of three-level converter (PCi-3L) [22], belongs to the group of finite control set model predictive control methods (FCS-MPC). In the PCi-3L strategy the switches are controlled directly without modulation. This is performed by online minimizing of specific cost function J. Depending on the definition cost function, we can control many different variables, e.g. current, dc-link voltage, switching frequency, etc. Cost function is calculated for all converter voltage vectors. Minimum value of J determines the optimal switching combinations.

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Modulation Strategy for Multiphase Neutral-Point-Clamped Converters

Cited by 105 publications

References 30 publications

A new modulation method for multilevel converters

A new modulation method for multilevel converters

Generalized PWM-Based Method for Multiphase Neutral-Point-Clamped Converters With Capacitor Voltage Balance Capability

Predictive and look-up table control methods of a three-level AC-DC converter under distorted grid voltage

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