In this paper, a new topology for cascaded multilevel inverter based on quasi-Zsource converter is proposed. In the proposed topology the magnitude of output DC voltage is not limited to the sum of magnitude of DC voltage sources. Moreover, the reliability of the circuit due to capability of short circuit by Z-source network is increased. The quasi-Zsource converter in different modes is analyzed and the voltage gain is obtained. Also, the values of quasi-Z-source network components are designed. In the proposed topology, the number of DC voltage sources, the number of switches, installation area and cost in comparison with conventional multilevel inverters are significantly reduced. Three algorithms to determine the magnitude of DC voltage sources are proposed. Then the optimal structures for the minimum number of switches and DC voltage sources to generate the maximum voltage levels are presented. Moreover, the control method for the proposed topology is described. To verify the performance of the proposed topology, simulation and experimental results of proposed topology are presented.

This paper introduces a novel two transistors forward topology employing a zsource to achieve ZVZCS and power transformer resetting for various applications. Comparing with the forward converter, this topology has the advantage of displaying ZCS condition with an added Z-source and no additional switches when the switches turn on, and that ZVS condition happens when the switches turn off. Duty cycle of the topology can exceed 50 percent. As a result, these converters are suitable for applications with high efficiency. In this paper, structure and properties of the topology will be discussed in details. Then the design principles will be presented. Finally, the benefits aforementioned will be approved in practice through a simple forward converter.

This paper presents a modified nine switch inverter with two inputs and two Zsource networks. This inverter has two DC inputs and two AC outputs. Input DC voltages can be boosted to the required level. Amplitude, frequency and phase of AC output voltages can be controlled, independently. The proposed converter can be used in applications with two unregulated DC sources, which require feeding two independent loads. Compared to the conventional structure, the proposed converter requires reduced number of semiconductor switches hence improved converter reliability and less volume. While the authors have already presented a similar inverter (single Z-source network dual-input dual-output inverter) with the above features, new inverter has some differences in the topology, control strategy and operation. In this paper, a new control strategy of space vector modulation for the new inverter is proposed. Also a new switching method utilizing carrier-based modulation concept is presented for both dual (proposed) and single Z-source network dual-input dual-output inverters. Performance of the proposed inverter is verified by simulation and experimental results.

In this paper, a series Z-source inverter based on a switched inductor cell is proposed for the first time. This inverter is able not only to increase the voltage gain, in comparison with the conventional Z–, source inverters, but also to solve the ST (shoot-through) state’, s problems. In this inverter, the value of the voltage gain is increased by an increase in the number of used diodes and inductors in the switched inductor cells. The low value of the capacitors’,voltage stress is another advantage of the proposed inverter. The voltage of the capacitors is increased from zero to the desired value by increasing the duty cycle of ST state from zero to the desired value. This leads to a soft start in the proposed inverter, which is impossible in conventional Zsource inverters. In this paper, in addition to investigating the operation of the proposed inverter in different operating modes, the value of voltage stress of the capacitors, current inductors, and the value of voltage gain are also calculated. Moreover, the proposed inverter is compared with the conventional Z-source inverters to investigate the advantages and disadvantages of it. Finally, the accuracy performance of the proposed inverter is verified through the simulation results in PSCAD/EMTDC software programs.