A new boost switched capacitor seven-level grid-tied inverter

In this paper, a new switched capacitor-based multilevel inverter structure is suggested. The proposed topology can generate seven-level output voltage waveform using ten power electronic switches and two floating capacitors. This structure has the ability to boost the input DC voltage, up to 1.5 times. Although this topology can generate an output waveform with large number of levels, it does not increase the voltage stress on the power electronic switches. There is no need for capacitor voltage balancing in this structure since the capacitors are balanced through charging and discharging modes of operation. In addition, the suggested switched capacitor inverter reduces the number of input dc power supplies and uses a single dc source such as a photovoltaic (PV) panel. Since the proposed inverter is an neutral point clamp based multilevel inverter topology, the leakage current is minimized and as a result the overall efficiency of the proposed system is increased. The operation modes and steady-state analysis of the proposed structure are explained in detail. In order to validate the feasibility of the proposed topology, some experimental results are presented in the grid connected mode of operation

Common-Ground-Type Single-Source High Step-Up Cascaded Multilevel Inverter for Transformerless PV Applications

The cascaded multilevel inverter (CMI) is one type of common inverter in industrial applications. This type of inverter can be synthesized either as a symmetric configuration with several identical H-bridge (HB) cells or as an asymmetric configuration with non-identical HB cells. In photovoltaic (PV) applications with the CMI, the PV modules can be used to replace the isolated dc sources; however, this brings inter-module leakage currents. To tackle the issue, the single-source CMI is preferred. Furthermore, in a grid-tied PV system, the main constraint is the capacitive leakage current. This problem can be addressed by providing a common ground, which is shared by PV modules and the ac grid. This paper thus proposes a topology that fulfills the mentioned requirements and thus, CMI is a promising inverter with wide-ranging industrial uses, such as PV applications. The proposed CMI topology also features high boosting capability, fault current limiting, and a transformerless configuration. To demonstrate the capabilities of this CMI, simulations and experimental results are provided

An improved nine‐level switched capacitor‐based inverter with voltage boosting capability and limitation of capacitor current spikes for PV applications

To proceed to a net zero carbon world and to mitigate the environmental challenges associated with it, integration speed of renewable energy sources such as photovoltaic (PV) systems has been increased around the world. Here, an improved switched-capacitor based nine-level inverter is introduced for PV applications. This topology has several benefits such as, voltage boosting feature, using a single DC source, reduction of capacitor charging current spike and extendable input voltage. This inverter produces nine-level output voltage waveform using single power supply. This topology, using identical two capacitors in parallel with a single DC source, can boost the input voltage. In this inverter to limit spike current of capacitor charging mode, an inductor is placed in the charging path of capacitors with a parallel diode. The power losses and overall efficiency analysis of the improved inverter are considered. To verify the accurate performance of inverter under a step change on power flows, simulation results are obtained by MATLAB/Simulink software and presented. To highlight the benefits of the inverter, a comparison of improved topology with most recent topologies is performed. Finally, to verify the feasibility and performance of the improved inverter, experimental results of a 770 W grid-tied prototype are presented

Fault Management Techniques to Enhance the Reliability of Power Electronic Converters

Publisher Copyright: © 2013 IEEE.The reliability of power electronic converters is a major concern in industrial applications because of using prone-to-failure elements such as high-power semiconductor devices and electronic capacitors. Hence, designing fault-tolerant inverters has been of great interest among researchers in both academia and industry over the last decade. Among the three stages of fault management, compensating the fault is the most important and challenging part. The techniques for fault compensation can be classified into three groups: hardware redundancy methods which use extra switches, legs, or modules to replace the faulty parts directly or indirectly, switching states redundancy methods which are about omitting and replacing the impossible switching states, and unbalance compensation including the techniques to compensate for the unbalances in the system caused by a fault. In this paper, an overview of fault-tolerant inverters is presented. A classification of fault-tolerant inverters is demonstrated and major cases in each of its categories are explained.Peer reviewe

A New Common Grounded Nine-Level Grid-Tied Inverter with Voltage Boosting Feature

Common grounded voltage source inverters are become very attractive in the photovoltaic (PV) grid-connected applications. In this paper a novel single input common grounded nine-level grid-connected inverter is presented. The proposed grid-tied inverter consists of eight switches, two diodes and three self-balanced capacitors. The proposed inverter can provide the voltage boosting feature with the voltage gain factor of 4 using the switched-capacitor strategy. In the suggested topology the neutral of the power grid is tied to the negative polarity of the input power dc supply, directly. Therefore, common mode voltage is reduced and leakage current concern is solved. In order to handle both powers (active and reactive), the current control technique is applied. Therefore, the proposed inverter can inject a high quality sinusoidal current to the power grid. Finally, the experimental results of 770 W prototype validate the good performance of the recommended inverter

Single-phase inverter with common grounded feature and connected into grid

Transformer-less inverters are widely used in grid-tied photovoltaic (PV) applications due to their characteristics such as higher efficiency and lower price. In common-ground transformer-less PV inverters, the neutral point of grid is connected to the negative polarity of the PV panel directly to bypass the parasitic capacitances and to mitigate the leakage current. In this study, a single phase transformer-less grid-tied inverter is proposed and to obtain the unique characteristics of the recommended grid-connected topology, the series-parallel switching technique of the switched capacitor module in a packed unit is applied. Also, by utilizing the common grounding method, the leakage current is eliminated. The provided inverter can generate three-level output voltage waveform. To generate the switching gate pulses of utilized power switches, the peak current controller method is applied. The injected power flows (active and reactive powers) are adjusted using peak current control (PCC) method. Finally, a completely adjusted sinusoidal current can be delivered to power grid. In the next section, the operation procedure, comparison results are presented. Finally, to verify the accurate operation and the theoretical equations of the proposed inverter, simulation results are presented

An Overview of Lifetime Management of Power Electronic Converters

Publisher Copyright: © 2013 IEEE.An expected lifetime of converters is of great importance for optimal decision-making in the planning of modern Power Electronic (PE) systems. Hence, the lifetime management of power electronic systems has attracted a lot of attention in academia and industry. This paper is a guideline for managing the lifetime of power converters. Analyzing the different kinds of failures, failure modes and their corresponding mechanisms are investigated in the first section along with the failure data needed as input parameters of the assessment. In the second section, lifetime prediction in two aspects of component-level and system level is discussed and all the possible techniques to achieve them are investigated and compared. All the steps required to predict the lifetime in the component-level including electrothermal modeling, cycle counting, lifetime model, damage accumulation, parameter estimation, and lifetime distribution are described and then system level methods consisting of reliability block diagrams, fault-tree analysis, and Markov chains are examined and compared. The last section contains the roadmap of the lifetime extension including the reliable design and condition monitoring.Peer reviewe

A New Common Grounded Quasi Z-Source DC-DC converter with Voltage Boosting Feature Applied for T-Type Inverter

This study presents a high step-up Quasi Z-source converter based on T-Type inverter. The proposed converter employs voltage multiplier cell and coupled inductors techniques with one magnetic core to create high voltage levels for inverter. The essential advantage of this converter is that the ground of input voltage source and grid is the same which eliminates the leakage current in Photovoltaic application. Also, the input current of this converter is continuous and the voltage stresses on main power switch and most of diodes are low. The mathematical analysis, operating principle, design consideration and comparison study for proposed converter are investigated and 730W PSCADE EMDCT software simulation results validate the accuracy of proposed converter