Three-level NPC 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

Sensorless DTC Based on Artificial Neural Network for Independent Control of Dual 5-Phase Induction Machine Fed by a Three-Level NPC Inverter

Sensorless DTC Based on Artificial Neural Network for Independent Control of Dual 5-Phase Induction Machine Fed by a Three-Level NPC Inverter

Technique for Mitigating Voltage Ripple of DC-Link Capacitors in a Three-Level NPC Utilizing a Zigzag Transformer

Technique for Mitigating Voltage Ripple of DC-Link Capacitors in a Three-Level NPC Utilizing a Zigzag Transformer

A carrier pulse width modulation for asymmetric three-level NPC inverter

A carrier pulse width modulation for asymmetric three-level NPC inverter

A Hybrid SVPWM-MPTC Control Strategy of Three-Level NPC Inverter-Fed PMSM Under the Balanced and Unbalanced DC Links

A Hybrid SVPWM-MPTC Control Strategy of Three-Level NPC Inverter-Fed PMSM Under the Balanced and Unbalanced DC Links

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.

Improved Iterative Learning Control for Three-Level NPC Inverter-Fed PMSM Drives With DC-Link Balancing

Improved Iterative Learning Control for Three-Level NPC Inverter-Fed PMSM Drives With DC-Link Balancing

Hybridized PWM Strategy for Three- and Multiphase Three-Level NPC Inverters

Hybridized PWM Strategy for Three- and Multiphase Three-Level NPC Inverters

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.

Circulating currents control method for paralleled three-level NPC inverters

Circulating currents control method for paralleled three-level NPC inverters

Non-Weighted Two-Stage Model Predictive Control Strategy Based on Three-Level NPC Inverter

This paper investigates the asynchronous motors driven by a Three-Level Neutral-Point-Clamped Voltage Source Inverter (3L-NPC-VSI) and aims to achieve control without weight factors and reduce torque ripple. It puts forward a non-weighted two-stage Finite-Control-Set Model Predictive Control (FCS-MPC) strategy. First, a hierarchical optimization method is adopted to address the difficulty of setting weight factors in traditional FCS-MPC applications. The method offers stratified designs of three performance indices, voltage jump, common-mode voltage, and current tracking, obviating the need for weight factor setting and reducing the calculation load of predictions. Secondly, to further mitigate torque ripple, an optimal vector or vector combination is implemented at the current control layer by adhering to the principle of minimal current tracking error. During the selection of the optimal vector combination, the first vector of the combination is chosen to be the vector at the end of the present cycle. This ensures that there is at most one switch within each control period, reducing the switching losses of the two-stage FCS-MPC. Lastly, detailed simulation and experimental analyses are conducted to verify the feasibility and effectiveness of the proposed strategy.

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.

Modified predictive torque control for balancing three-level NPC inverter-fed PMSM drives

Modified predictive torque control for balancing three-level NPC inverter-fed PMSM drives

Enhancement of fault ride-through capability of three-level NPC converter-based HVDC system through robust nonlinear control strategy

Voltage source converter-based high-voltage direct current (VSC-HVDC) transmission systems are becoming increasingly popular for long-distance power transmission due to their numerous advantages. However, the fault ride-through (FRT) capabil-ity of VSC-HVDC systems during AC faults remains a key challenge that needs to be addressed to ensure their uninterrupted operation under challenging grid conditions. This paper presents and analyzes a novel nonlinear control scheme based on a robust sliding mode control approach to improve the FRT capability of VSC-HVDC systems. The proposed control scheme based on the modification of the converter’s active power to make it more sensitive to any changes in voltage magnitude at the points of common coupling (PCCs) on the AC side. This helps to maintain the DC voltage sta-bility and prevent the converter from tripping during AC faults. The performance of the proposed control scheme is evaluated using a series of ex-perimental investigations using a digital signal processor (DSP) within Processor-in-the-Loop (PIL) quasi-real-time simulation. The PIL simulations closely examine the system’s response to AC faults with varying remaining voltages and durations. The results demonstrate that the proposed control scheme can effectively improve the FRT capability of VSC-HVDC systems and ensure their stable operation during AC faults.

On the Design and Analysis of a Weighting Factor Free-Based Predictive Flux Control Strategy for Three-Level NPC Inverter-Fed IM Drives

On the Design and Analysis of a Weighting Factor Free-Based Predictive Flux Control Strategy for Three-Level NPC Inverter-Fed IM Drives

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

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

Contribution to the Improvement of Sensorless DTC-SVM for Three-Level NPC Inverter-fed Induction Motor Drive

This paper deals with the high performance of multi-level direct torque control (DTC) for induction machines without speed and stator flux sensors. The estimation is performed using a sliding mode observer, which is known for its robustness in high and low-speed operations, the control is based on a backstopping speed controller. This control technique was introduced years ago to circumvent the problems of sensitivity to parametric variations, it presents a high dynamic but their major problems are the variable switching frequency, the size and complexity of the switching tables, and undulations of the torque. The proposed approach is to replace switching tables with constant switching frequency control using three-level spatial vector modulation (SVM). Theoretical elements and simulation results are presented and discussed. As a result, the flux and torque ripple of three-level DTC-SVM control is greatly reduced compared to the flux and torque ripple of DTC-classic control. The advantages of the training system have been validated by the simulation results.

A Fault-Tolerant Control Strategy for Three-Level Grid-Connected NPC Inverters after Single-Arm Failure with Optimized SVPWM

Three-level NPC inverters have been widely used in grid-connected systems due to their superior performance compared with two-level inverters, but more switches lead to high fault probability. Meanwhile, the neutral point potential (NPP) fluctuation of the DC link is an inherent problem of three-level NPC inverters. To keep the three-level NPC inverter running stably after single-arm failure, a fault-tolerant control strategy based on an optimised space vector pulse width modulation (SVPWM) is proposed in this paper. Firstly, the common-mode voltage (CMV) of the postfault three-level NPC inverter is analysed and then the preliminary synthesis principles of the reference voltage vector are determined. Then, in order to ensure the NPP balance and the quality of the grid-connected currents, the reference voltage vector synthesis rules are optimised, a low-pass filter (LPF) and a hysteresis comparator are designed, respectively, to ensure the quality of grid-connected currents and effectively decrease the DC link NPP deviation. Finally, the simulation results show that the proposed fault-tolerant control strategy can realize the stable and reliable operation of the grid-connected three-level NPC inverter after single-arm failure, and the CMV can be reduced significantly, the quality of grid-connected currents is also improved. The proposed fault-tolerant strategy also shows good performance when the grid-connected currents change.