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

Design, Analysis, and Implementation of a Transformer-less Step-up Converter with Continuous Input Current and High Voltage Gain Ratio

This paper proposes a high-step converter with reduced voltage and current stresses. This converter does not employ coupled inductors and transformers, reducing volume and weight besides eliminating leakage inductance issues. The low voltage and current stresses make it possible to employ low current/voltage rate semiconductors, resulting in a decrease in loss and expense. Moreover, switches turn ON/OFF simultaneously, leading to a simple switch drive circuit. The steady-state analysis is studied, including ideal voltage gain, current and voltage stresses, DCM, and CCM, besides converter loss and efficiency. In addition, the converters\u27 control procedure and frequency response are investigated, and recently introduced topologies are compared with the proposed converter. This converter uses fewer components than investigated topologies to achieve significant voltage gain at small duty cycle values. The experimental analysis verifies the theoretical relations and the converter performance

A Single-Phase High Gain Active-Switched Quasi Z-Source NNPC Inverter

Impedance source-based multilevel inverters have recently gained popularity for new renewable energy sources. This study describes a quasi Z-source (qZS) based single phase five level nested neutral point clamped (SL-NNPC). Compared to previous topologies, the suggested qZS, which uses active switches, has input continuous current and common ground between the input dc source and the converter\u27s output dc source, which is the same as the inverter\u27s input dc link. In addition, this converter features a high voltage gain and low voltage stress on the switch and diodes. To regulate the flying capacitor voltages and consequently the inverter\u27s output current, the Model predictive control (MPC) method for the 5L-NNPC inverter is implemented

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

Implementation and Efficiency Calculation of Fuel-Cell Vehicles Using a Bidirectional DC/DC Converter with ZVS

Fuel-cell (FC) vehicles are attracting much interest due to their advantages. In FC-powered vehicles, the application of DC/DC converters is for interfacing between the FC and the DC bus. Due to some of the inherent characteristics of FCs, such as large variations in the output voltage, efficiency improvement for different operation points is vital for optimal performance. Moreover, the bidirectional operation can be useful, for example, to charge supercapacitors in electric vehicles (EVs). In this article, the role of a DC/DC converter is as part of the interface system, and efficiency analysis is performed for an EV application. The design and application of the DC/DC converter are optimised based on the EV application\u27s use case scenario. First, the converter\u27s efficiency is analysed for a range of switching frequencies, input voltages, and duty cycles, with basic operations considered later. All the required relations and operating conditions are explained, and simulation results confirm the theoretical analysis

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

High Step-up Common Grounded Switched Quasi Z-Source DC-DC Converter Using Coupled Inductor with Small Signal Analysis

Publisher Copyright: AuthorsIn this article, a new common grounded switched quasi Z-source DC-DC converter is proposed. In the proposed converter, an additional switch and a diode are used compared to the conventional quasi Z-source converter. The proposed converter provides some benefits by using a coupled inductor and switched capacitor unit. These features are providing voltage-boosting capability using a small range of duty cycles, low voltage stress on semiconductors (switches and diodes), and continuous input current waveform. In this topology, the null of the load is connected to the negative terminal of the input DC source, directly. So, the common mode voltage is kept constant. In this case, the proposed DC-DC converter is suitable for photovoltaic (PV) power generation systems to boost the voltage of PV panels. In this paper, the proposed converter and operation modes are described completely. Also, in order to show the advantages and differences of the proposed topology with other DC-DC high-step up converters, a comparative comparison study is considered. Also, the small signal analysis and control strategy of the proposed converter are provided. In addition, design considerations of the used components are given. Then, the power loss analysis of the converter is provided. Finally, in order to prove the accurate performance of the suggested topology and verify the advantages and analysis, an experimental prototype is built at 250 W output power and the related results are provided.Peer reviewe

High Step-up Common Grounded Switched Quasi Z-Source dc-dc Converter Using Coupled Inductor

This paper presents a common grounded switched quasi-Z-source dc-dc converter by using one more power switch and diode in comparison with the conventional quasi-Z-source converter. The presented converter has used coupled inductor and switched capacitor cell in order to reach the following advantages: achieving high voltage gain with a small range of duty cycle, continuous input current, the low voltage stress on power switches, low voltage stress on output diode. These facilities make it reasonable to use in PV system applications to increase the level of the voltage. In this paper, the principle and analysis of operation modes for the presented converter are given and also, the comparison of the presented structure with conventional structures is evaluated. Finally, to certify the performance of the proposed converter and its theoretical relationships, the simulation results of 250 W of the proposed converter are presented