Three-phase Voltage-fed Quasi-Z-Source AC-AC Converter

The paper proposes a novel three-phase voltage-fed quasi-Z-source ac-ac converter topology to overcome the shortcomings of the traditional three-phase AC-AC chopper.The quantitative relationship between the output voltage and duty-ratio is deduced by investigating the topology and operating principle.It can provide buck-boost function,and the output voltage of the circuit can keep stable in the case of voltage sagging.Simulation is performed using the MATLAB software,and the experimental circuit is built based on the simulation results,the simulation and experimental results verify the correctness and feasibility of the proposed ac-ac converter topology.

SVM strategy and analysis of a three-phase quasi-Z-source inverter with high voltage transmission ratio

Herein,we propose a novel three-phase quasi-Z-source inverter with a high voltage transmission ratio to address challenges such as high switching loss and sizeable magnetic components in the basic quasi-Z-source inverter.The proposed circuit topology,control strategy,and related analysis are presented.The circuit topology of the inverter comprises a quasi-Z-source network with an integrated magnetic inductor,an active clamp circuit,a three-phase inverter bridge,and an output LC filter,all of which are connected in series.An improved 12-sector space vector modulation scheme is proposed based on the root-mean-square value of the voltage and the instantaneous value of the current.Furthermore,analyses of the inverter voltage transmission ratio,resonant process,and parametric design guidelines for integrated magnetic inductor and zero-voltage switching conditions are presented.Experimental results on a 1-kVA prototype inverter demonstrate that the proposed inverter exhibits a higher transmission ratio and efficiency than existing inverters;thus,the proposed inverter would have broad prospects in low-voltage DC-AC applications.

Applying Sliding Mode Control to Suppress Double Frequency Voltage Ripples in Single-phase Quasi-Z-source Inverters

The inherent double-line frequency ripple(DFR)of the single-phase quasi-Z-Source inverter(qZSI)strongly affects performance and design of the whole system,which requires hardware improvement methods such as additional semiconductor components or increasing the volume of capacitors and inductors.As a result,hardware solutions increase the price,and the volume and also reduces reliability of the system.In this paper,as a non-hardware solution,a sliding mode control(SMC)method is presented to control the voltage of the qZSI capacitor.To suppress the DFR,a second-order harmonic is injected into the capacitor reference voltage.Simulation and experimental results show that the introduced controller will have satisfactory results in reducing the DFR without any hardware changes in the qZSI,such as increasing the volume of the capacitor and inductor,adding a semiconductor,or increasing the frequency.A simulation model and experimental prototype are provided to demonstrate the validation of the effectiveness of the proposed controller.

Quasi-Z-Source Based Bidirectional DC-DC Converter and Its Control Strategy

This paper presents a quasi-Z-source based isolated bidirectional DC-DC converter(qZIBDC)for renewable energy applications.The converter utilizes a dual active bridge circuit with a quasi-Z-source network on both sides,so the converter works as buck/boost converter from either side.It has a wider input/output voltage operating range,soft-switching capabilities without additional devices,and higher boost capability than a traditional dual active bridge circuit.Apart from that,shoot-through states are incorporated in its operating cycle to boost the input voltage resulting in high reliability of the proposed converter.Due to the symmetrical structure of the circuit,there is no defined high voltage or low voltage side as in traditional isolated bidirectional DC-DC converter.The operating principle and control strategy of the proposed converter are presented.Simulation and experimental results are provided to verify the effectiveness of the proposed converter topology and its control strategy.

High step-up quasi-Z-source DC–DC converters with single switched capacitor branch

Aiming to integrate the respective merits of the switched-capacitor converter and the quasi-Z-source converter. An novel high step-up quasi-Z-source DC–DC converter with a single switched-capacitor branch is proposed. Compared to other high boost DC–DC converters,the proposed converter can provide higher output voltage gain, lower current stress across the switches, and lower voltage stress across the output diodes by using the same or similar passive and active components. Therefore, the efficiency and reliability of the converter can be improved.The topological derivation, operating principle, parameter selection, and comparison with other DC–DC converters are presented. Finally, both simulations and experimental results are given to verify the characteristics of the proposed converter.