The increase in linking photovoltaic (PV) power plants to utility grids are due to the world expansion in PV systems and its advantages of low running cost, renewable, etc. Although PV is now considered one of the main power sources in many countries, it has low efficiency. Therefore, the big issue to improve the efficiency is to enhance the interface inverters’ efficiency. Different inverter topologies have been proposed to relate to the PV panels; each has advantages and disadvantages. These topologies can be classified into two-stage and single-stage (impedance network) inverters. Impedance network inverters overcome the problems of traditional inverters and seek to realize the advantages of a two-stage system and reduce the number of power conversions. However, to the authors’ best knowledge, there is no comprehensive review of the applications of the impedance source inverter for the PV system, including the control techniques. Therefore, this paper reviewed the existing topologies by paying attention to four key research issues: 1) various impedance network inverters and discusses the main structures from the point of view of the PV application, 2) control techniques suitable for impedance source inverters, comparing them in terms of complexity and theoretical performance, 3) investigation into the most important control methods used to connect the inverter output current with the network voltage, and 4) Challenges and future direction. Finally, this paper is provided as a brief reference to help researchers choose the appropriate impedance source inverter topologies for their applications and the preferred control and modulation methods for this type.

Three-phase converters based on insulated-gate bipolar transistors (IGBTs) are widely used in various industrial applications. Faults in IGBTs can significantly affect the operation and safety of the power electronic equipment and loads. It is critical to accurately detect power inverter faults as soon as they occur to ensure system availability and high-power quality. This study provides a novel integration of signal and data-driven fault-diagnosis approaches for detecting open-circuit switch faults in three-phase inverters. The proposed technique uses the average root-mean-square (RMS) ratio of the phase current as the key extraction feature. This feature can be used to estimate the fault types and faulty switches (es) irrespective of changes in the running load. Ensemble-bagged machine learning classification was used to accurately predict the faulty switch of the inverter. The results demonstrate the ability of the proposed fault diagnosis technique to identify single-, double-, and triple-switch fault (s). The experimental results also attested to the simulation of multiple fault diagnosis. A unique feature of this technique is its ability to estimate faulty switches under various inverter-operating conditions.

Nine-switch Inverter (NSI) has been recently introduced for independent control of dual AC motors. Although this topology reduces the number of active switches by 25% compared to conventional Inverters, it has a main conceptual shortcoming due to voltage gain limitations. In NSI, the voltage gains of both outputs are relatively low, while their maximum achievable magnitudes depend on the phase angle between the two sets. In order to mitigate this problem, this paper introduces a new dual output Nine-Switch Boost Inverter (NSBI) topology with a minimum number of passive elements. The detailed analysis of NSBI is introduced, while the required modifications to conventional PWM strategies of the NSI are explained to ensure an acceptable voltage boosting ratio while a high-quality voltage output is obtained. Among different PWM schemes, a modified discontinuous PWM scheme is found optimum with this proposed topology to minimize the voltage stress across switches and improve the input current and output voltage quality. The proposed topology is also validated under both common-frequency and different-frequency modes of operations. Moreover, a clear picture of the NSBI performance compared with other possible counterparts is introduced. The theoretical findings have been corroborated using simulation and experimentally.

Research on Common-Mode-Voltage (CMV) reduction in multiphase drive systems has recently met an intensified interest in the available literature. This paper first explores two existing space-vector-based CMV reduction schemes for five-phase Voltage Source Inverters (VSIs), denoted as CMVR1 and CMVR2, which reduce the CMV by 40% and 80%, respectively. Moreover, a new space-vector-based CMV reduction scheme, termed as CMVR3, is proposed that not only minimizes the CMV but also reduces the overall switching losses when compared with the other schemes. The optimal duty cycles and the switching sequence of all scheme are introduced. Since the implementation of space-vector-based schemes using look-up tables is a relatively complex and time-consuming process, this paper proposes a simpler scalar PWM approach. This approach can easily be implemented using embedded PWM modules of most commercial Digital Signal Processors (DSPs). To evaluate the performance of the presented CMV reduction schemes, a detailed evaluation study is presented. The optimal CMVR scheme over the full modulation index range is also highlighted. The theoretical findings are verified using a prototype five-phase induction machine through simulations and experimentally.

This paper proposes an approach to link photovoltaic arrays with the AC grid using Z-source inverter (ZSI) and quasi-Z-source inverter (QZSI) topologies. These topologies boost the DC-link voltage and invert it to AC voltage in one stage, resulting in a reduction in the overall system size and cost. The paper presents a control technique that fixes the DC-link voltage on the inverter bridge terminals, tracks the maximum power point (MPPT), and controls the amount and quality of power injected into the grid using unity power factor. The proposed control algorithm utilizes two independent control variables, shoot-through duty cycle (ST) and modulation index, to decouple the control of the DC and AC sides. The effectiveness of the proposed control technique is verified through simulations of a grid-connected PV system. The results demonstrate that the proposed system can efficiently extract maximum power from PV arrays while regulating the DC-link voltage and ensuring unity power factor operation. Additionally, experimental testing of ZSI/QZSI further confirms the results of analysis and simulation.

This study introduces a detailed analysis, design and implementation of a three-phase matrix converter based on space-vector modulation technique. The modulation strategy is described and modelled. All steps of hardware design using discrete semiconductor devices are given. The modulator is implemented using a digital signal processor. The experimental results for passive loading and three-phase induction motor conditions are given. Then the converter performance is discussed.