Design and Control of Small DC-Link Capacitor-Based Three-Level Inverter with Neutral-Point Voltage Balancing

In, Hyo-Chul; Kim, Seok-Min; Lee, Kyo-Beum

doi:10.3390/en11061435

Cited by 14 publications

(12 citation statements)

References 27 publications

(32 reference statements)

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“…The controller presented in the previous section provides, at each sampling time, the values for u 1 , u 2 , u 3 and u 4 . The corresponding values for d αp , d αn , d βp and d βn can be obtained solving the system of Equations (13), (14), (19) and 20yielding…”

Section: Modulation Strategymentioning

confidence: 99%

“…Some of them use additional circuitry [7][8][9], but this would lead to an increase in cost, losses and complexity in hardware. Other authors use different control techniques with algorithms of varying difficulty [10][11][12][13][14][15]. One of these control techniques [13] uses a modification of virtual space vector [16] (denoted as mVSVPWM in this paper).…”

Section: Introductionmentioning

confidence: 99%

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Integrated Control and Modulation for Three-Level NPC Rectifiers

Ventosa‐Cutillas

Montero-Robina

Umbría³

et al. 2019

Energies

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This paper uses a novel approach for the control of three-level neutral-point-clamped (NPC) rectifiers in order to tackle the capacitor voltage balance problem. A distinctive feature of the new control approach is that it is based on a model which is written in terms of the duty ratios for each phase at each level. Hence, the system model presents nine duty cycle variables. Despite the fact that this formulation is different from the usual ones, it is shown that the control problem of currents and dc-link voltage can be formulated in a similar way to conventional methods. Furthermore, the control of the capacitor voltage balance can be expressed by means of equations that are decoupled from the currents and dc-link voltage dynamics, which results in a specific controller for the voltage balancing that does not affect the previous dynamics. A key point of the proposed approach is that part of the modulation stage is implicit in the formulation. Two particular controllers are compared in this paper. The first one fulfills the different control objectives at the expense of a large number of commutations. This problem is overcome in a new proposed controller, which presents similar performance and a satisfactory number of commutations. Experimental results are performed showing the effectiveness compared with a modified virtual space vector modulation with capacitor voltage balance capabilities.

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Section: Modulation Strategymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Integrated Control and Modulation for Three-Level NPC Rectifiers

Ventosa‐Cutillas

Montero-Robina

Umbría³

et al. 2019

Energies

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“…The unbalance of capacitor voltages is the big problem for this configuration. However, this issue has been addressed by several methods [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

A Modified Model Predictive Power Control for Grid-Connected T-Type Inverter with Reduced Computational Complexity

et al. 2019

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This study proposed a modified power strategy based on model predictive control for a grid-connected three-level T-type inverter. The controller utilizes the mathematical model to forecast the performance of the grid current, the balance of DC-bus capacitor voltages and switching frequency. The proposed method outlines a new technique to formulate a control objective. The control objective includes the absolute error of the inverter voltage reference and its possible values instead of the grid current error. By using the modified equivalent transformations in the cost function, the execution time was reduced 22% compared to the traditional model predictive control while maintaining the high dynamic performances of the power and low total harmonic distortion of the current. A comparative investigation showed that the proposed method obtains a high-performance control compared with the classical power control scheme with linear PI controllers and space vector modulation. The feasibility of the proposed method was verified by the simulation and experimental results.

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“…Three-level neutral-point-clamped (NPC) converters are popularly used in renewable energy generation and energy storage, which have been widely recognized as promising solutions to the problems associated with increasing environmental challenges [1][2][3]. Compared to the two-level topology, three-level NPC converters are much more attractive because of their lower voltage stress on power electronic devices, lower total harmonic distortion, higher efficiency, and even better economic performance [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

A Study on Neutral-Point Potential in Three-Level NPC Converters

et al. 2019

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This paper proposes an accurate mathematical model of three-level neutral-point-clamped (NPC) converters that can accurately represent the midpoint potential drift of the DC link with parameter perturbation. The mathematical relationships between the fluctuation in neutral-point voltage, the parametric perturbation, and the capacitance error are obtained as mathematical expressions in this model. The expressions can be used to quantitatively analyze the reason for the neutral-point voltage imbalance and balancing effect based on a zero-sequence voltage injection. The injected zero-sequence voltage, which can be used to balance the DC-side voltages with the combined action of active current, can be easily obtained from the proposed model. A balancing control under four-quadrant operation modes is proposed by considering the active current to verify the effectiveness of this model. Both the simulation and experiment results validate the excellent performance of the proposed model compared to the conventional model.Energies 2019, 12, 3367 2 of 22 pulse width modulation (SVPWM) strategies were proposed to adjust the dwell time between small vector switching states by judging the direction of the neutral point current and the deviation of the neutral point potential. However, the calculation methods are complex and difficult to implement. In [24], a pulse width modulation (PWM) strategy was proposed where the both DC-side voltages can be adjusted independently through zero-sequence voltage injections and compensation for the unbalance in neutral point voltages, but the process of calculating the injected zero-sequence voltages is complicated.However, these control strategies, above all, ignore the quantitative analysis of the potential drift and balancing effect based on zero-sequence voltage injection. Meanwhile, if the converter is used in renewable energy generation and energy storage with four-quadrant operation modes, the DC voltage balancing control is very difficult to realize in existing literature because the active current of the converter is not taken into consideration.This paper proposes an accurate mathematical model of the neutral-point potential in three-level NPC converters based on the SPWM strategy with parametric perturbation and zero-sequence voltage injection. The model is simple and direct, but very interesting and valuable. To the best of our knowledge, it is novel and has not been previously reported in the literature. From this model, the relationship between the drift potential value and all the AC-side and DC-side variables can be deduced by quantitative analyses. The calculated drift potential value shows that the basic reason for the neutral-point potential drift is the uneven shunt loss caused by the parametric perturbation, and the capacitance error has no influence on it. The balancing control can be directly obtained based on the combined action of the injected zero-sequence voltage and active current. The required zero-sequence voltage for balancing control can be easily calculated b...

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Design and Control of Small DC-Link Capacitor-Based Three-Level Inverter with Neutral-Point Voltage Balancing

Cited by 14 publications

References 27 publications

Integrated Control and Modulation for Three-Level NPC Rectifiers

Integrated Control and Modulation for Three-Level NPC Rectifiers

A Modified Model Predictive Power Control for Grid-Connected T-Type Inverter with Reduced Computational Complexity

A Study on Neutral-Point Potential in Three-Level NPC Converters

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