Three-phase Inverter Research Articles

A quad DC source switched three-phase multilevel DC-link inverter topology

The concept of an isolated DC source cascaded multilevel inverter finds good solutions for generating quality output voltage for low-medium power applications. It shapes the output voltage from three levels into a number of steps closer to a sinusoidal shape using small DC sources or batteries. Several advantages have been sighted like lower voltage stress and bearing noise, and lesser THD. However, a common issue in the MLIs is the total components required which increase with the rise in voltage levels. This paper proposes a three-phase MLI design having several isolated quad voltage source modules including an H-Bridge inverter. The design suggested claims reduced switching components for current conduction paths showing improved output quality. The operational features of the suggested MLI have been analyzed using Matlab/Simulink software, furthermore, an experimental module is constructed for demonstrating the effectiveness of the simulated results.

Modeling, Control and Simulation of a High-Current DC-DC Converter for Fuel Cell Applications

In this paper, a high-current two-stage DC-DC converter fed by a Proton Exchange Membrane Fuel Cell (PEMFC) is studied. The converter consists of two three-phase full-bridge inverters connected through three AC coupled inductors. The mathematical models of both converter and PEMFC are first presented, and a control scheme that ensures a high power factor at the AC stage and a regulated voltage at the DC load is then implemented. The performance of the proposed control system is verified through digital simulations.

Simulation based study of Maximum Power Point Tracking and Frequency Regulation for Stand-alone Solar Photovoltaic Systems

The main objective of this paper is to develop a simulation model of stand-alone solar photovoltaic (PV) system based on mathematical models. A maximum power point tracking (MPPT) algorithm based on incremental conductance method is applied to extract the maximum power from solar PV energy conversion system. A DC/DC boost converter allows the MPPT to control the intermediate voltage. To regulate to voltage at load side a voltage source converter (VSC) based controller is applied to generate the pulse signal for three-phase inverter. The frequency regulation controller is developed based on conventional phase locked loop (PLL) system along with resistive dumping loads. A simulation model based on mathematical model Matlab®/Simulink®/SimPower® is constructed interface. Results using from simulation are stated to demonstrate the behaviour of stand alone solar PV energy conversion system.

Photovoltaic Power Conversion System Based on Cascaded Inverters with Synchronized Space-Vector Modulation

The paper presents results of investigation of dual-inverter-bases power conversion system with synchronized pulsewidth modulation (PWM) for photovoltaic application. This system topology includes two insulated strings of photovoltaic panels, feeding two standard three-phase inverters, connected to grid by a three-phase transformer with the open winding configuration on primary side. Algorithms of synchronized PWM provide in this case continuous voltage synchronization both in each inverter and in the load. Simulations show a behavior of the systems with low switching frequency, with both continuous and discontinuous versions of synchronized PWM.

A Contribution to Isolated and Grid-Connected Photovoltaic Systems under Shadow Conditions

The power supplied by photovoltaic panel is sensitive to radiation incident on itself. Both isolated and grid connected applications are very important output voltage. The load usually works in constant voltage. Variation on radiation levels may lead to no voltage. This work presents the use of a PID controller in a converter able to provide constant voltage for an isolated system even during radiation variation in solar panel. presents a PI controller to a three-phase inverter connected system. The controller is designed power produced by the photovoltaic panels on the grid.

Power Quality in Renewable Energy Systems  Challenges and Opportunities

Power quality in traditional power systems is concerned with voltage problems caused by abnormal operation or nonlinear load behavior. The integration of renewable energy into the power grid introduces new power quality problems. In addition to the intermittency of renewable production, which leads to more frequent voltage fluctuation, and the switching in the power electronics interfaces, which injects high-frequency harmonics into the system, harmonic resonance and other dynamics power quality problems become more prevalent due to the complex and fast dynamics and control of power electronics interfaces. This paper reviews the sources of harmonic resonance involving renewable energy and presents a systematic method to identify and characterize such dynamic power quality problems. A distributed generation test-bed is also presented as an experimental platform for the study of system harmonic resonance and other control-related power quality and stability problems. Measurement results involving single-phase solar and three-phase wind inverters are presented to validate the analysis method and to demonstrate possible mitigation techniques. The need for advanced autonomous control that enhances system stability and mitigates system harmonic resonance are discussed. Issues related to electromagnetic interference (EMI) generated by renewable energy sources and the need to develop EMI compliance requirements for such sources are also discussed.

Phase modulation of carriers for cascaded multilevel three-phase inverters

Cascaded multilevel three-phase inverters are commonly used in industrial applications and the quality of these inverters is highly dependent on the modulation techniques. The common mode voltage is one of the factors affecting the quality of the three-phase inverter output voltage. This paper proposes a carrier phase modulation method for cascade multilevel inverters to reduce the magnitude of common-mode voltage magnitude and harmonics. In the proposed method, the carrier phase modulator is considered as an adaptive controller and the phase of carrier is completely controlled by the magnitude of control signal. The phase modulation has a high immunity to the noises compared with the modulations of frequency and amplitude because it is difficult for noises to intrude into the phase of carrier. In addition, the algorithm of carrier phase modulation is simple and requires little memory. Moreover, the number of switching commutations of the proposed method also reduces significantly. Simulation and experiment results based on a cascaded five-level three-phase inverter system have confirmed the effectiveness of the proposed method compared with that of the popular methods using unmodulated carriers such as phase disposition (PD) and phase opposite disposition (POD).

Switched Z-Source Boost Converter in Hybrid Renewable Energy System for Grid-Tied Applications

The world's focus is shifting toward Renewable Energy Sources (RES) as a result of the sharp rise in energy demand and the depletion of conventional energy sources. Distributed generation (DG) units developed on RES are easily and reliably integrated into grid due to microgrid technology. Inverters are typically used to integrate DGs into microgrid. At present, the fastestgrowing renewable sources of electricity in the world is photovoltaic (PV) and wind energy conversion system (WECS), which evolved in response to growing environmental concerns about the risks of climate change connected with power generation. Recent technological developments have made it a top priority for researchers to find ways to enhance the efficiency of hybrid systems and the power converter stage. In order to achieve transmission losses and ensure energy savings, a new 13-bus system is developed in this work for regulating the output voltage in distribution networks. Switched Z-source Boost converter along with Proportional Integral (PI) controller is employed to boost the voltage obtained from PV system. A battery converter along with a bi-directional battery is connected to the DC link, to store energy generated by Hybrid Renewable Energy System (HRES) in excess amount. The obtained DC link voltage is transferred to three-phase voltage source inverter (VSI) for the conversion of DC to AC voltage. Effective harmonic reduction is attained with the aid of LC filter coupled to Three phase grid, and the PI controller associated to the grid supports in achieving effective grid synchronization. The proposed research is validated using MATLAB Simulink by considering the 13-bus system and an efficiency of 96.8 % is obtained with 0.93% Total Harmonic Distortion (THD).

Analytical investigation of induction motor drive under DC-link voltage ripple in voltage source inverter.

Analytical analysis and mathematical model of ripple components of the DC-link voltage of three-phase voltage source inverter and its influence on an induction motor drive both in time and frequency domain are presented in this paper. The analytical expressions for the voltage and current space-vectors as a function of the DC-link voltage pulsation are derived. From the current space vectors the torque behavior is estimated again as a function of DC-link voltage pulsation. The proposed analytical method is based on the mixed p-z approach enabling presentation of the results in closed-form.

Simulation system of intelligent photovoltaic grid-connected inverter considering fuzzy PI control

The grid connected inverter is the core component of the photovoltaic grid connected power generation system, which mainly converts the direct current of the photovoltaic matrix into alternating current that meets the grid connected requirements, playing a key role in the efficient and stable operation of the photovoltaic grid connected power generation system.This paper uses fuzzy PI control model which to improve the performance of intelligent photovoltaic grid-connected inverter to simulate the intelligent photovoltaic inverter system, using mathematical analysis and reasoning methods for model analysis,adopts two-stage three-phase LCL grid-connected inverter, establishes mathematical models in two-phase synchronous rotating and two-phase static coordinate systems, and adopts an active damping strategy based on grid-connected current. Based on existing research and empirical analysis,aiming at the disadvantage of poor dynamic response of repetitive control, an improved repetitive control strategy is adopted, and the controller is analyzed from two aspects of stability and dynamic performance, and the simulation model of photovoltaic grid-connected power generation system is built. Use experimental analysis method to verify the effectiveness of the model in this article,The experimental results show that the simulation system of intelligent photovoltaic grid-connected inverter considering fuzzy PI control proposed in this paper has certain effects.

Improved Feedback Quantizer with Discrete Space Vector.

The use of advanced modulation and control schemes for power converters, such as a Feedback Quantizer and Predictive Control, is widely studied in the literature. This work focuses on improving the closed-loop modulation scheme called Feedback Quantizer, which is applied to a three-phase voltage source inverter. This scheme has the natural behavior of mitigating harmonics at low frequencies, which are detrimental to electrical equipment such as transformers. This modulation scheme also provides good tracking for the voltage reference at the fundamental frequency. On the other hand, the disadvantage of this scheme is that it has a variable switching frequency, creating a harmonic spectrum in frequency dispersion, and it also needs a small sampling time to obtain good results. The proposed scheme to improve the modulation scheme is based on a Discrete Space Vector with virtual vectors to obtain a better approximation of the optimal vectors for use in the algorithm. The proposal improves the conventional scheme at a high sampling time (200 μs), obtaining a THD less than 2% in the load current, decreases the noise created by the conventional scheme, and provides a fixed switching frequency. Experimental tests demonstrate the correct operation of the proposed scheme.

New stability results for discrete-time switched systems under admissible edge-dependent average persistent dwell-time or admissible edge-dependent persistent dwell-time switching

This paper is devoted to the stability analysis of a class of discrete-time switched systems under newly designed switching regularities. The utilized switching is extended from the primitive mode-dependent persistent dwell-time switching. By integrating the existing admissible edge-dependent average dwell-time switching into the mode-dependent persistent dwell-time regime, a novel admissible edge-dependent average persistent dwell-time strategy involving the notion of admissible transition edges is proposed. The integrated admissible edge-dependent average dwell-time switching has been confirmed to be superior to mode-dependent average dwell-time switching. This superiority makes the proposed switching more general than the relaxed mode-dependent persistent dwell-time switching in the literature. Even if the embedded admissible edge-dependent average dwell-time restrictions degrade to admissible edge-dependent dwell-time ones under special parameter settings, the resulting admissible edge-dependent persistent dwell-time switching retains the advantage of admissible transition edges to generalize the original mode-dependent persistent dwell-time switching. Meanwhile, to remove the switching information reliance in the existing multiple convex Lyapunov functions, an improved multiple convex Lyapunov function method is devised. The designed Lyapunov function can be used to implement broader feasible ranges and tighter lower bounds of admissible edge-dependent average persistent dwell-time (or admissible edge-dependent persistent dwell-time). Finally, the validity and efficiency of the presented approaches are illustrated by a three-phase inverter and a numerical example.

Research on topology of a novel three-phase four-leg fault-tolerant NPC inverter

Research on topology of a novel three-phase four-leg fault-tolerant NPC inverter

Current limiting algorithm for three-phase grid-connected inverters

Current limiting algorithm for three-phase grid-connected inverters

Fault-tolerant control for three-phase three-level T-type inverters with a redundant leg

Fault-tolerant control for three-phase three-level T-type inverters with a redundant leg

Asymmetric Space Vector Pulse Width Modulation for the Phase Current Reconstruction in Three-Phase Inverters

Asymmetric Space Vector Pulse Width Modulation for the Phase Current Reconstruction in Three-Phase Inverters

Learning and Outperforming the Model Predictive Control With a Linear ϵ-Support Vector Machine for Power Converter

This paper presents a linear ϵ error insensitive support vector machine (ϵ-SVM) learned from the model predictive control (MPC) with very limited training samples. Unlike the existing learning-based MPC which takes the same inputs as the MPC, the ϵ-SVM learns from historical data as well. Such structure is found to have both feedforward and feedback elements that improve performance. Besides, using the ϵ error-insensitive tube also increases the noise cancellation capability. The experiment is carried out on a three-phase inverter with an L-C filter and shows that the linear ϵ-SVM-MPC not only has better performance than the artificial neural networks (ANN) MPC, but also outperforms the online MPC in both low THD values and small tracking errors regardless the load conditions. Moreover, the use of the linear kernel significantly reduces the time complexity to <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</i> (1), which is much less than <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</i> (2 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ⁿ</i> ) in either online MPC or ANN-MPC. Therefore, the linear ϵ-SVM-MPC has provided an effective way to implement the MPC and it is preferable for the DSP. This article is accompanied by a video demonstrating the real-time operation.

A Transformerless Photovoltaic System Employing a Cubic Cell Boost Converter for Low Voltage Application

A photovoltaic (PV) system is commonly used to satisfy the power demand of the utility. This paper investigates the utilization of a high voltage gain Cubic Cell Boost Converter (CCBC) in a transformerless photovoltaic (PV) system for low voltage applications. The proposed system is a combination of a CCBC and a three-phase inverter creating a two-stage three-phase PV system. The CCBC is linked with the low-scale PV sources to step up its input DC voltage and maintain a constant DC bus voltage by employing the Perturb and Observe (P&amp;O) Maximum Power Point Tracking (MPPT) control algorithm. The DC bus is further connected to an LCL filter based three-phase inverter using a synchronous reference frame (dq) control scheme to power the three-phase utility. The proposed combination is validated by simulating in MATLAB/ SIMULINK environment for a 5.5 kW PV source and achieved an efficiency of 91% with 1.91% of inverter Total Harmonic Distortion (THD) at unity power factor. In the proposed system, CCBC with P&amp;O MPPT control provides a high step-up DC bus voltage with less input current ripple and output voltage ripple and maintains a constant DC bus under variable solar irradiance. This work does not account for the common leakage current that is often produced in a transformerless PV system.

A Robust Data-Driven Method for Open-Circuit Fault Diagnosis of Power Switches in Three-Phase Inverters With Low-Quality Data

A Robust Data-Driven Method for Open-Circuit Fault Diagnosis of Power Switches in Three-Phase Inverters With Low-Quality Data

Large-signal Stability Analysis of Three-phase Grid-following Inverters

Large-signal Stability Analysis of Three-phase Grid-following Inverters