First, the impedance source idea is used to alleviate the problems of Voltage source Inverters (VSI), and Current source Inverters (CSI), which leads to the introduction of the Z-source Inverter (ZSI). Afterwards, not only did the Z-source cells were used in the inverter topologies, but they were also added to other power electronic converters, such as dc-dc choppers, ac-dc rectifiers, and ac-ac converters. Moreover, these power electronic converters, which have Z-source cells, are widely used in different applications. In particular, the existing single-phase ac-ac Z-source converters are reviewed in this paper, and their different features are studied in detail. In the past decades, the single-phase Z-source ac-ac converters have attracted significant attention due to their unique features, such as single-stage power conversion, boost in-phase, and buck out-of-phase features. Therefore, several modified or improved structures along with different control methods have been introduced to solve their problems and limitations. Based on the four features, these structures can be categorized into four groups: without magnetic coupling, with magnetic coupling, able to change the frequency, and inherent commutation. In this review, a general diagram is depicted, which many of the existing topologies can be obtained from it. Additionally, new topologies can be obtained by having this general diagram. After studying these structures, a comparative study is made to obtain the advantages and disadvantages of each. In the end, some advice and recommendations are given to develop and obtain new structures.

This paper proposes a multi-stage power generation system suitable for renewable energy sources, which is composed of a DC-DC power converter and a three-phase inverter. The DC-DC power converter is a boost converter to convert the output voltage of the DC source into two voltage sources. The DC-DC converter has two switches operates like a continuous conduction mode. The input current of DC-DC converter has low ripple and voltage of semiconductors is lower than the output voltage. The three-phase inverter is a T-type inverter. This inverter requires two balance DC sources. The inverter part converts the two output voltage sources of DC-DC power converter into a five-level line to line AC voltage. Simulation results are given to show the overall system performance, including AC voltagegeneration. A prototype is developed and tested to verify the performance of the converter.

Most existing power converters and industrial motor drive systems draw non-sinusoidal currents from the supply. Non-sinusoidal currents contained harm harmonics disturb the power supply which it causes serious concern for reliability. Other equipments that use the same power supply are adversely affected. This paper suggests the operation and performance of a new modified AC/DC converter that allows bi-directional power flow. It also provides improved power factor and reduces harmonic magnitude and disturbance to the supply by system. The bi-directional feature allows recovery of regenerative energy of loads, back to the power supply and the converters. The proposed converter has high potential for industrial applications, such as electronically controlled traction system, lifts and generally industrial motor drive systems which can increase overall efficiency and reliability.

A comparative study of passive and active waveshaping filter (current-source fed CSF switch mode rectifier SMR converter supplied from single-phase AC supply) presented in this study. Active harmonic filter (boost converter) used to reduce the harmonics at the main supply by controlling the duty cycle of the filter. Passive waveshaping filter reduce the harmonics at the supply in a simple way. The two circuits are designed and implemented using MATLAB/Simulink®. It is found that use of active harmonic filter increases the input power factor approximately from 0.63 to 0.81. While, in passive filter the PF increased to 0.86. Moreover, total harmonic distortion THDi was reduced in passive method more in comparison with active one.