Space-vector-modulated three-level inverters with a single Z-source network

The Z-source inverter is a relatively recent converter topology that exhibits both voltage-buck and voltage-boost capability. The Z-source concept can be applied to all dc-to-ac, ac-to-dc, ac-to-ac, and dc-to-dc power conversion whether two-level or multilevel. However, multilevel converters offer many benefits for higher power applications. Previous publications have shown the control of a Z-source neutral point clamped inverter using the carrier based modulation technique. This paper presents the control of a Z-source neutral point clamped inverter using the space vector modulation technique. This gives a number of benefits, both in terms of implementation and harmonic performance. The adopted approach enables the operation of the Z-source arrangement to be optimised and implemented digitally without introducing any extra commutations. The proposed techniques are demonstrated both in simulation and through experimental results from a prototype converter

Implementation of Passivity-based Control of Four-Leg Inverter for Transformerless Three-Phase Solar Photovoltaic Systems

This study explores the application of a passivity-based control technique (PBC) with an artificial neuro-fuzzy inference system (ANFIS) in a grid-connected Solar Photovoltaic (SPV) generating system for estimating reference grid currents. To optimise the tracking of the maximum power point (MPPT) between the solar photovoltaic (SPV) system and the DC bus, a DC – DC boost converter (BC) is utilised. This converter is connected to a four-leg, three-level neutral-point-clamped converter (4-leg 3L-NPC), interfaced with a three-phase, four-wire distribution system. The four-leg 4-leg 3L-NPC of the SPV generating system with Space vector pulse width modulation technique (SVPWM) is utilised for reducing common-mode voltage (CMV), leakage current (LC), reactive power for zero voltage regulation, power factor correction, load balancing, and the elimination of load harmonic currents in the proposed distribution system.The performance analysis of the proposed system is conducted on the Matlab/Simulink platform. Additionally, a comparative analysis is presented, contrasting the proposed system with a 3-phase 4-leg T-type neutral-point-clamped converter (TNPC) employing the PBC technique followed by ANFIS

Direct Instantaneous Power Control of Three-level Grid-connected

Power electronic grid-connected inverters are widely applied as grid interface in renewable energy sources. This paper presents direct instantaneous power control of a three-phase three-level Neutral Point Clamped (NPC) grid-connected inverter in photovoltaic generation systems. The system consists of a PV array, DC/DC converter, three-level NPC LC filter and the grid. In order to achieve maximum power point  tracking (MPPT), an adaptive perturb and observe MPPT is used. For balancing the neutral point (NP) voltage, the control scheme through proportional integral (PI) control according to  the direction of the NP current based on redundant vector selection is used. Direct instantaneous power control is developed in a rotating synchronous dq reference frame with space vector modulation with improved operation performance study of the positive sequence detector (PSD) plus a synchronous a synchronous reference frame phase-locked loop (PLL) as the synchronization method. The performance of the proposed method is investigated by a grid-connected photovoltaic system with a nominal power of 12kW. The feasibility of the proposed method is verified through experimental results, showing good steady-state and dynamic performance

A Three-Level Single Stage A-Source Inverter With the Ability to Generate Active Voltage Vector During Shoot-Through State

Single-stage boosting capability of impedance network (IN) inverters makes this family of inverters an attractive choice for DC/AC applications with low input DC voltage. A specific time of shoot-through (ST) state is required to achieve the required voltage gain. Conventionally ST state and zero output voltage vector should be applied simultaneously. This constraint limits the modulation index and increases the voltage stress of the semiconductor devices, particularly for applications requiring a high boosting factor. In this paper, as the boosting stage for a three-level inverter, a new modified configuration of A-source IN with two series outputs is proposed and connected to a 10-switches three-level inverter. Besides generating two outputs by a single IN, the proposed DC/AC inverter is able to apply an active voltage vector during the ST state. This capability improves the DC/AC voltage gain, increases the modulation index, and decreases the required ST time. The operation principles are described, and the steady-state relations are derived. It is compared with other magnetically coupled INs in terms of boost factor and voltage stress of switches. Considering the 10-switches three-level inverter as the front-end inverter, an adopted maximum boost strategy using the space vector modulation is developed targeting minimum ST time. Finally, a laboratory prototype of the converter is developed, and several tests are carried out. The results validate the given theories and simulations.© The Authors. Published by IEEE. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/fi=vertaisarvioitu|en=peerReviewed

PERFORMANCE ANALYSIS OF FIVE LEVEL Z SOURCE NEUTRAL POINT CLAMPED MULTILEVEL INVERTER USING SPWM AND SVPWM

The scope of this paper is to reduce the harmonic content and to boost the output voltage by introducing an emerging technique termed as Z-Source multilevel inverter. The Z-Source inverter had overcome many drawbacks in traditional inverters (Voltage source & Current source Inverters).The main advantage of Z- Source inverter is the presence of a shoot through the period (Short circuit) which plays an important role in boosting the voltage. When the number of levels in the output voltage of multilevel inverter is increased then accordingly the harmonic content is also reduced. Normally for a multilevel inverter the output voltage is restricted to the summation of all the input voltage values.To enhance this feature Z-Source is introduced with a multilevel inverter to obtain boosted voltage along with low harmonic distortion.The proposed methodology analysis the Z-Source Neutral point clamped inverter using the Space vector modulation technique with MATLAB/Simulink model and the related parameters is analyzed

Switched-capacitor integrated single-phase (2n+1)-levels boost inverter for grid-tied photovoltaic (pv) applications

© 2019 IEEE. This paper presents a switched-capacitor integrated (2N+1)-level (N≥2) boost inverter for single-phase photovoltaic (PV) applications. It consists of N modular switching cells, where each cell consists of two switched capacitors and three active switching elements. A boost converter at the front side of the switching cells helps to maintain the capacitor voltage balance during different operation modes. With this arrangement, the inverter is capable to generate 2N+1 output voltage levels, and able to accommodate a wide range of input voltage. Detailed analysis followed by simulation and experimental results of a 5-level inverter as an example is presented to verify the proposed concept. Further, comparison with other multilevel inverter topologies is presented to show the merit of the proposed concept

Emerging Converter Topologies and Control for Grid Connected Photovoltaic Systems

Continuous cost reduction of photovoltaic (PV) systems and the rise of power auctions resulted in the establishment of PV power not only as a green energy source but also as a cost-effective solution to the electricity generation market. Various commercial solutions for grid-connected PV systems are available at any power level, ranging from multi-megawatt utility-scale solar farms to sub-kilowatt residential PV installations. Compared to utility-scale systems, the feasibility of small-scale residential PV installations is still limited by existing technologies that have not yet properly address issues like operation in weak grids, opaque and partial shading, etc. New market drivers such as warranty improvement to match the PV module lifespan, operation voltage range extension for application flexibility, and embedded energy storage for load shifting have again put small-scale PV systems in the spotlight. This Special Issue collects the latest developments in the field of power electronic converter topologies, control, design, and optimization for better energy yield, power conversion efficiency, reliability, and longer lifetime of the small-scale PV systems. This Special Issue will serve as a reference and update for academics, researchers, and practicing engineers to inspire new research and developments that pave the way for next-generation PV systems for residential and small commercial applications