NPC Converter Research Articles

Enhanced Active Voltage Regulation Capability for Three-Level NPC Converters with the Space Vector Modulation Method

Enhanced Active Voltage Regulation Capability for Three-Level NPC Converters with the Space Vector Modulation Method

Sliding Mode Control for NPC Converters via a Dual Layer Nested Adaptive Tuning Technique

Sliding Mode Control for NPC Converters via a Dual Layer Nested Adaptive Tuning Technique

Online condition monitoring for DC-link capacitors of three-level NPC converters using noninvasive signal injection

This paper introduces an online method for monitoring the health condition of the DC-link in three-level NPC converters. This method does not require hardware changes or modifications to the control algorithm. It involves injecting a zero-sequence signal, added to the system reference voltages to generate a neutral-point current injection. A square waveform with an interharmonic cycle frequency is used for the signal injection to minimize estimation errors caused by existing signals. This combined signal allows for the simultaneous estimation of the capacitor equivalent series resistance (ESR) and capacitance (C) at different frequency components using wavelet decomposition. Additionally, a balance between the magnitudes of the system reference voltage and the signal injection is established to prevent power quality issues. Besides, the capacitor parameters are estimated in the time-frequency domain, enabling tracking of capacitor degradation and wear-out failure. A comparison with a Fourier-based approach shows that this method provides highly accurate capacitor parameter estimation with less than 2% errors, instilling confidence in its results. Experimental results from a three-level NPC converter’s laboratory setup demonstrate the proposed method’s effectiveness.

Control of dual star induction generator based on multi-level inverter used in wind energy conversion system

This paper presents vector control of dual star induction generator (DSIG) integrated into variable speed wind energy and supplied by three-level NPC converters. Now the DSIG is the most common among multiphase machines when used in high power generation systems, which is associated with two converters. Maximum power point tracking (MPPT) for extracting a maximum of power fluctuating wind speed is illustrated. In order to decrease the fluctuations that appear in the currents generated by DSIG to the electrical network, we propose the NPC structure three-level inverter. Simulation results of a 1.5 MW Wind turbine are presented to illustrate the validity of this application.

PSO-enhanced discrete-time integrated sliding mode-based control of three-level NPC converter for grid-connected PV-FC distributed generation system

This study proposes the control of a three-level NPC converter applied in a PV-FC hybrid generation system based on discrete-time integral sliding mode control (DISMC) combined with the particle swarm optimization (PSO) technique. First, the comprehensive depiction and modeling of the system's main components are initially presented. Then, the controller's detailed design procedure is given. The sliding manifold is designed to have a fast dynamic response, and its stability analysis is verified using the Lyapunov direct method. Next, the optimization procedure is introduced to calculate the optimal values of the DISMC gains. Furthermore, a power management strategy is examined within the proposed control system to maximize the utility of the power produced by the hybrid system; the control is done through the designed PSO-DISMC to allow decoupled control of the active and reactive powers in two distinct modes of operation (the feeder-flow control (FFC) and the unit-power control (UPC) modes). The simulation of the approach is conducted in MATLAB/Simulink, and the findings demonstrate the effectiveness and robustness of the proposed control strategy.

Open-Switch Fault Diagnosis in Back-to-Back NPC Converters of PMSG-Based WTS via Zero Range Value of Phase Currents

Open-Switch Fault Diagnosis in Back-to-Back NPC Converters of PMSG-Based WTS via Zero Range Value of Phase Currents

Quantitative Analysis of Balancing Range for Single-Phase 3L-NPC Converters

Multiple techniques have been suggested to achieve control balance in single-phase three-level neutral-point clamped (3L-NPC) converters. Nevertheless, there is a deficiency of quantitative calculations related to the extent of balancing. Operating beyond the balancing range may result in a sequence of safety incidents. This paper presents a conceptualization of the 3L-NPC converter as two cascaded H-bridges. By employing power conservation principles, the balancing range for the NPC converter is derived, and two novel methods are investigated to broaden the balance range in accordance with the calculated balance range. A comparison is made among the balancing ranges under different balancing control methods. This study establishes a theoretical foundation to ensure the secure and stable operation of the NPC converter.

A Honeycomb-Like Predictive Controller With a Reduced Computational Burden for Three-Level NPC Converters

A Honeycomb-Like Predictive Controller With a Reduced Computational Burden for Three-Level NPC Converters

Experimental Comparison of Carrier and Space Vector PWM Control Methods for Three-Phase NPC Converters

Multilevel converters are powerful converters in the medium-voltage high-power range. Inside this family of converters, the three-level neutral point clamped converter has its own importance. The main control methods associated with this converter are the carrier-based PWM with added DC components and the space vector PWM. Two of the most important features of the NPC converter are the neutral point balance and the output voltage spectrum. Both control methods efficiently manage the two characteristics. This paper experimentally compares these two issues and shows that the two methods produce almost the same results; the choice between one and the other should be made according to other requirements.

Investigation and Evaluation of Multilevel H- NPC Converter for Electrically Driven Trains

In this paper is analyzed and simulated on the computer the operation of a three level H-bridge converter as well as its parallel operations. Based on the simulation results the operating behavior between a) a three level H-bridge neutral point clamped converter, b) a three level H-bridge neutral point clamped converter with parallel elements and c) two three level H-bridge neutral point clamped converters parallel connected is being compared. From the simulation results is obvious that in the first two cases the ripples, the distortion in primary and secondary winding currents, and the power factor are quite satisfactory and almost identical to each other. In the third case as compared with the first two, we observe that current harmonics with higher amplitude appear in the primary winding of the transformer.

Dual Phase-Shifted PWM Method With Enhanced Harmonic Performance for Parallel NPC Converters in Grid-Connected Applications

Dual Phase-Shifted PWM Method With Enhanced Harmonic Performance for Parallel NPC Converters in Grid-Connected Applications

A Hybrid Asymmetric Average Zero CMV PWM Strategy With Four Nearest Vectors to Optimize Harmonic Distortion for a Three-Level NPC Converter

A Hybrid Asymmetric Average Zero CMV PWM Strategy With Four Nearest Vectors to Optimize Harmonic Distortion for a Three-Level NPC Converter

Development of a Generalized Multilevel SVM and Capacitor Voltage Balancing Strategy for Multiphase Three-Level NPC Converters

Development of a Generalized Multilevel SVM and Capacitor Voltage Balancing Strategy for Multiphase Three-Level NPC Converters

Fast-Processing Capacitor Voltage Balancing Algorithm for Single-End Five-Level NPC Converters Based on Redundant Level Modulation

Fast-Processing Capacitor Voltage Balancing Algorithm for Single-End Five-Level NPC Converters Based on Redundant Level Modulation

Finite-Time Sliding Mode Control for NPC Converters With Enhanced Disturbance Compensation

Finite-Time Sliding Mode Control for NPC Converters With Enhanced Disturbance Compensation

A Basic Design Tool for Grid-Connected AC–DC Converters Using Silcon Carbide MOSFETs

The design and optimization of power converters is a key factor in the growth and development of the power electronics field. However, the process of designing a power converter is not straightforward, and engineers often rely on experience and intuition, sometimes requiring time-consuming computer simulations. This paper presents a tool for the basic design of grid-connected AC–DC converters. The design tool takes specifications and operating conditions for two-level and three-level NPC converter topologies and derives a draft design. The tool calculates the input filter’s electrical parameters, the converter’s losses, the temperature rise of the power semiconductor devices, and the ripple current and voltage of the DC-link capacitor. In order to validate the proposed design tool, four AC–DC converters using SiC MOSFETs were designed. Based on the design results, simulation models and prototypes were fabricated to verify the performance and confirm that the proposed design tool can be used in the basic design process of converters.

A Robust High-Quality Current Control With Fast Convergence for Three-Level NPC Converters in Microenergy Systems

Three-level neutral-point-clamped (3L-NPC) power converters are necessary interfaces to form micro-energy systems. Naturally, designing a suitable control scheme, featuring superior dynamics, strong robustness, and simple structure, is a promising solution to guarantee more efficient operation of converter. This paper proposes a robust high-quality current control strategy for the 3L-NPC power converter in the stationary <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\alpha \beta$</tex-math></inline-formula> frame. A super-twisting algorithm coupled with a Luenberger observer current controller is proposed to deal with the poor sinusoidal current tracking issue due to the existing inductance/grid frequency deviations and the disturbance of the sinusoidal dynamic nature. Additionally, an extended sliding mode disturbance observer based proportional control is built to dramatically enhance voltage regulation performance, in the case of capacitance deviations and unknown dc-loads. Experimental data confirm the effectiveness of the proposed solution outperforms the conventional proportional-resonant/-integral control in terms of accurate tracking current/voltage, anti-disturbance, and grid current total harmonic distortion.

A Passivity-based direct power control scheme of a back to back NPC converter

In this paper, a direct power control (DPC) is proposed in order to improve the power dispatch in electrical power grids, as well as in microgrids. The objective of defining the active power and reactive power as state variables is to get a representation of the first level in a hierarchical control. The DPC model is studied under passivity rules, and an implementation of passivity-based control is proposed. Simulations are carried out to show the effectiveness of the proposed research.

A 3-layered feedforward back-propagation ANN-based SVPWM control for neutral point clamped converter for PV grid integration

Most of the power electronic converters based on the devices such as Silicon Controlled Rectifiers (SCRs) have been broadly utilized in home, business, and modern use in recent years. Despite their many benefits, these power electronic converters have major issues such as pulling harmonic current and the reactive part of the current from the supply, as well as having a highly nonlinear characteristic. The harmonics produced by the current supplied by these nonlinear elements cause voltage distortion at the common coupling point, which is causing problems for the functioning of number of sensitive instruments and other consumer appliances. Artificial Neural Networks (ANN) are a type of Artificial Intelligence (AI) approach that has been applied to improve the efficiency and regulation of the converter. In order to avoid the need for a Digital Signal Processors (DSP) by avoiding the online timing computations for various voltage space vectors in various regions and sectors and produce higher pulse resolution, an ANN-based space vector pulse width modulation (SVPWM) technique is proposed in this paper. The analysis of a 3-layered feedforward back propagation ANN algorithm based SVPWM control for NPC converter used to integrate PV source to grid has been evaluated and found to be better as compared to traditional techniques.

Impact of Sequential Model Predictive Control on Induction Motor Performance: Comparison of Converter Topologies

Finite Set Model Predictive Control (FS-MPC) is a widely used technique in power electronic converter applications. One challenge in FS-MPC implementation is selecting appropriate weighting factors, as there is currently no established methodology for finding the best values. An alternative approach is to consider cost functions without weighting factors, as used by the Sequential Model Predictive Control (SMPC). In this paper, the performance of SMPC applied to induction motors is analyzed. The SMPC strategy involves sequentially evaluating simple cost functions by considering a limited number of available switching states for the power electronic converter. This number is the control parameter of the SMPC. The parameter’s domains and a selection criteria based on THD were established in this investigation. The power converter topologies studied include the Voltage Source Inverter (VSI) and the Neutral Point Clamped three-level (3L-NPC). Simulations performed in PLECS software and Hardware-in-the-Loop (HIL) tests using an RT Box for valid parameters satisfy the characteristics of the classical predictive control, such as good control variables tracking and high dynamic response. For a VSI converter, increasing the control parameter results in reduced harmonic distortion, while for an NPC converter, optimal results are achieved with control parameter values within a specific range.