Z-source Topology Research Articles

Analysis of Different PWM Techniques for Enhanced Ultrahigh Gain Z-Network Topology

In these modern times, the Z-source inverters (ZSIs) have become a revolutionary invention ever since the year 2002. The pulse-width modulation (PWM) technique used for most of the ZSIs is simple boost control PWM (SBC-PWM), and the SBC-PWM implies for a greater voltage stress on the inverter bridge and provides less boost factor. Likewise, many topologies for the basic Z-source topologies are evolved, and different PWM techniques are applied to them such as maximum boost control (MBC), maximum boost control with third harmonic injection (MBC-THI), maximum constant boost control (MCBC), and constant boost control with third harmonic injection (CBC-THI). All these mentioned PWM techniques are compared, and the converter opted in this paper is an enhanced ultrahigh gain active-switched quasi-Z-source inverter (EUHG-qZSI). The comparisons discussed in this brief are bridge stress, voltage gain, and voltage boost variation under each control strategy implementation. The theoretical and simulation evaluation for the abovementioned findings is presented in this paper, and the best PWM among them is maximum boost control (MBC).

PI Controlled Bridged Grid-Connected Solar PV Network for Electric Vehicle Battery Charging

The Z-source inverter (ZSI) topology replaces multiple stages into a single stage in power conversion so it is going to be an appropriate topology for 1-phase grid-connected PV system. In this paper, the various z-source topologies are discussed as available in different literature. This paper has proposed a proportional and integral (PI) Controlled bridged grid-connected solar photovoltaic (PV) network for electrical vehicle charging. The different modulation techniques applied in these topologies have been described. The bridged grid-connected network equipped with solar modules can prove effective in developing charging infrastructures for electric vehicles (EVs) at residential or commercial complexes. The different parameters of this suggested topology may vary during different time instants of a whole day at different modes of procedure i.e solar PV generation to the grid, EV to grid, and both PV and EV to grid. The simulation work has been done with the PWM technique to obtain battery voltage and grid voltage, Fast Fourier Transform, and total harmonic distortion.

PI-based ZSVM Control of Quasi-Z-Source Inverter for Photovoltaic Applications in Standalone Mode

The power converters Z-source topology are becoming a promoter solution for the energy conversion. This topology has the ability to boost and convert the voltage in a single-stage, unlike the famous two-stage conventionnel structure. The Quasi-Z-Source Inverter (QZSI) is nowadays the subject of several research works. However, it is the most suitable for PV applications, due to his continuous input current, which allows to harvest the maximum power available from the PV panels. In this regard, this paper investigates the dynamic characteristics of the QZSI through the small signal analysis, as well as the scheme control with the SVPWM technique for QZSI in standalone mode. The simulation results illustrate the practicability and the validity of the control scheme proposed.

Modulation Technique for Modified Active Quasi-Z-Source Inverter with Common-Mode Voltage Reduction

In Z-source topologies, a high-amplitude common-mode voltage can occur when shoot-through states are inserted. In this study, a new space vector pulse-width modulation for an active quasi-Z-source topology is proposed to operate at a high modulation index and reduce the common-mode voltage to one-third of the DC-link voltage. Moreover, the quality of the output voltage is improved by operation with a high modulation index and decreasing the switching loss of the H-bridge switches. The detailed operating principles of the active quasi-Z-source topology using the proposed space vector modulation (SVM) method are presented. A simulation model was built, and an experimental prototype was verified to correct the theoretical analysis.

Modeling and analysis of nonlinear behavior for synchronous switching Z-source topology

Modeling and analysis of nonlinear behavior for synchronous switching Z-source topology

Switched-Capacitor High Voltage Gain Z-Source Converter With Common Ground and Reduced Passive Component

Conventional dc-dc Boost converter has limited boost capacity, and its power device suffers high voltage stress. A novel Z-source based dc-dc boost converter featured with high step-up capability and low device voltage stress is proposed in this paper. The proposed topology can also provide a common ground for input and output, which is lacking in the traditional Z-source topology. Compared with other high step-up topologies, the proposed converter can achieve higher voltage gain under the same duty ratio and maintain low voltage stresses on the switch and diode. Moreover, there are fewer passive components in the proposed structure than in other structures. The steady-state analysis for the continuous conduction mode and discontinuous conduction mode is also provided in this manuscript. Finally, a prototype circuit with 40V-60V input voltage, 400V output voltage and 200W output power is implemented in the laboratory. Experiment results confirm the analysis and the features of the proposed converter.

Analysis and Design of Quasi-Z-Source Equivalent DC–DC Boost Converters

In this article, three switched-capacitor-based Z-source equivalent dc–dc boost converter (SCZEBC) topologies are proposed. The basis for these topological evolutions is the shifted L-C-D cell of the fourth-order boost converter on the front-end side, whereas a charge-pump cell on the upstream side. This hybrid combination results in quasi-Z-source equivalent dc–dc boost conversion along with enhanced voltage boosting capability. The operating duty ratio of the proposed topologies is less than 0.5 like in the conventional Z-source dc–dc converter (ZSC) topologies. In comparison to the existing Z-source topologies, remarkable features of the proposed SCZEBC topologies are: low source current ripple, common ground, and low voltage stress on capacitors and active devices. A detailed steady-state analysis is presented to identify the salient features of the proposed topologies and is thereafter compared with the existing ZSCs. Small-signal analysis is established and a voltage-mode controller is designed. In the controller design stage, a modulus margin 0.5–0.75 is adopted to ensure tradeoff between robustness and performance of the proposed converter topologies. A 48 to 220 V, 100-W prototype is built to demonstrate the effectiveness of the SCZEBC. The steady-state and closed-loop response measurements validate the theoretical studies.

A New Bidirectional DC Circuit Breaker With Fault Decision-Making Capability for DC Microgrid

DC circuit breaker (DCCB) plays an important role in dc system protection as an execution unit for disconnecting fault lines. However, due to the nature of dc current, it is a challenge for DCCB to quickly turn off and isolate the fault current. Therefore, a new bidirectional DCCB with decision-making capability based on Z-source topology is proposed in this article, which is able to respond to a fault in a few microseconds. The proposed topology uses only one coupled inductor with a central tap structure in the core part, which improves the utilization ratio of the coupled inductor and reduces the volume and cost of the DCCB. Compared with previous DCCBs, the proposed topology has a simpler structure, fewer windings and components, and smaller volume. In this article, the turn off process of the proposed topology under the line fault condition is analyzed in detail, and the hardware circuit design process is given. The performance of the proposed topology was verified by MATLAB simulation and hardware experiments.

Inverter Topology Selection for Photovoltaic Power Systems

This article is devoted to the task of selection of photovoltaic power system inverter that would comprehend to all of the demands that could be applied to it. The challenge of creating efficient and reliable converter for the renewable energy systems that implies solar panels as primary energy sources is well-known since the first day of their existence as a possible choice for the role of the only power source in the system. The great breakthrough in the field of photovoltaic power system converters design was achieved in late 80’s-early 90’s years of the 20th century due to the several positive circumstances that included rapid evolution of the semiconductor industry at whole which sums up in the development of a new generation of power switches that was capable to operate in higher voltage and current ranges which was unreachable for the prior generation switches and new microcontrollers that was able to maintain more complex control algorithms than ones that were used before which in general resulted in significant downsizing of the resulting device and made it possible to practically develop power inverters with complex topologies that was considered over sophisticated and unreliable before. These factors leaded to the development of numerous new topologies with the main goal of transformation losses reduction and power efficiency increase. The desired result was obtained either thru the fulfilling the demands invoked by the photovoltaic sources operation features (z-source topologies) or power system topology features and reduction of output voltage THD ratio (multilevel inverters). But consideration of only one type of factors has not allowed achieving the maximum result in power losses task. Thus solution of the determined task should be started from complete identification and broad consideration of the main factors that define set of demands that converter has to face. In this article parameters of THD ratio of the inverter’s output voltage, photovoltaic source’s operation features and power system topology specifics were considered as the most valuable parameters that affects the power conversion losses values and was discovered in details based on a survey of the existing publications in the field of the study, international and local standards of consumer voltage quality parameters and practical results of the most popular and widespread topologies simulation in order to obtain an output voltage THD ratio. The achieved results demonstrate that inverter topology that would be able to satisfy all of the requirements has to have modular structure to be able to maintain the proper THD ratio and connect to the most popular types of the photovoltaic power system topologies and be based on the z-source topologies to imply the photovoltaic sources operation features. Therefore as a conclusion a cascaded multilevel inverter with a separated input DC sources topology that is based on quasi-z-source modules was recommended as a solution that could also be used as a base for the further power converter development.

Multiport Isolated link with Current-Fed Z-Source Converters to Manage Power Imbalance in PV Applications

In order to address power imbalance in large-scale PV systems, this paper presents a multiport isolated medium-frequency (MF) link to process different power levels from PV arrays, using current-fed Z-source inverters (CZSI) modules to drive the energy from the PV array to the MF link in a single power stage. The MF link provides the galvanic isolation required by many codes and standards to integrate a system to the grid. The multiport configuration of the MF link allows the system to process different power levels on each primary port and, being all ports magnetically coupled, provide balanced power levels on secondary ports which can be used for multilevel converters applications. Additionally, the current-fed version of the Z-source topology offers natural protection against short-circuit damage enhancing reliability of the system. The analysis of CZSI cells and the study of asymmetrical power levels transference, as well as simulation and experimental results are presented.

Active Rectification For the Optimal Command of Bidirectional Resonant Wireless Power Transfer Robust to Severe Circuit Parameters Deviations

In this article, a method resorting to active rectification for the optimal control of a bidirectional resonant wireless power transfer system is proposed. Benefiting from a dual active bridge topology and without requiring any additional dc-dc converter, the real and the imaginary parts of the equivalent load impedance are modulated simultaneously and independently, for achieving optimal operating conditions despite circuit parameters deviations. Based on a first harmonic analysis, the methodology and its beneficial impacts against variations in the windings mutual inductance or against mistuned resonant capacitor are presented and illustrated. By an argued discussion, the proposed method extent is enlarged to changes in any circuit parameters. Time-domain simulations of the converters topology and command demonstrates the method effectiveness by achieving the system maximum efficiency. Controllability restrictions preventing the compensation of the most severe parameters variations are highlighted. Associated with the limited voltage producible by conventional full-bridge converters, the latter restrictions are surmounted with success by considering Z-source topologies for the front-end and back-end converters.

A comparative study of Z-source inverter and enhanced topologies

This paper does some theoretical analysis and simulation studies on the most common topologies of Z-source inverter. As we all know, the traditional Z-source inverter has some problems, such as the voltage of the capacitor which belongs to this topology is higher and there is a startup shock, which caused researchers proposed a variety of improved Z-source topologies to solve these problems. Some of these topologies can increase boost capacity, and some can reduce the capacitor voltage. However, these topologies can improve only part of the problems of the traditional Z-source inverter, which leads to that the users are hard to choose which topologies. Faced with this situation, eleven Z-source topologies are analyzed in terms of boost capacity, inductance start-up current, capacitance stress and economy in this paper. Finally, two kinds of promising topologies were gotten.

A Z-Source-Based Bidirectional DC Circuit Breaker With Fault Current Limitation and Interruption Capabilities

DC microgrids have some attractive characteristics, which have being investigated to utilize in future electrical power systems. However, they have several essential challenges, such as limiting and interrupting fault current, which should be rectified to have high-performance dc microgrids. In this paper, an efficient dc bidirectional fault current limiter and interrupter (FCLI) based on Z-source topology is proposed to overcome some of the challenges in dc microgrids. The FCLI is a multifunction device, by which power flow direction control, circuit breaking, fault current limiting, and interrupting in a dc system can be handled. Analytical analysis of the FCLI is discussed in detail for different operation modes. Performance of the proposed FCLI in the different operation modes is evaluated using some simulations and experiments. The results confirm high capability of the device to realize appropriate operation in dc systems. Fast response time of fault current limitation and interruption, simple and reliable structure, and negligible conduction loss are the main features of the proposed FCLI.

Impedance Source Based Multi Phase Inverter Fed Variable Speed PMBLDC Motor Using Advance controller for Torque Ripple Minimization

This paper presents the advance controlling system for multiphase PMBLDC motor. This permanent magnet synchronous motor has copper losses in stator, current vibration and harmonics due to wrong selection of rotor shape is generated by the voltage saturation and more torque ripple. This voltage saturation affects the performance of the motor. The proposed multiphase permanent magnet BLDC motor is to reduce the voltage saturation and also to minimize the torque ripple. The multiphase motor have more handling capacity, high reliability and to produce high torque at same ampere volume of machine. This multiphase topology is requiring high dc source and effective control method for high speed operation. The introduced Z-source topology is used to improve source voltage boost up ability without using any DC/DC converters. Further, it reduces the line harmonics, enhance the load power factor, gives ride through ability in the course of input voltage sags and increases inverter reliability. The IFOC control strategy is possible to achieve high reliable operation at input voltage sag conditions. The proposed Z-source networks as well as IFOC scheme based multi phase motor to attain the minimum torque ripples and high voltage gain in ASD (adjustable speed drive) are analyzed in MATLAB/ SIMULINK environment.

Comparison of Fault Diagnostics on Z-Source and Trans Z-Source Inverter Fed Induction Motor Drives

This paper investigates the performance of Trans Z- source inverter (abbreviated as T ZSI) fed induction motor drive under various fault conditions. With development in power electronics and remarkable improvement in control techniques, induction motor has evolved as a variable speed machine. For critical applications, continuous operation of the drive is of paramount importance. However, their performance is restricted by electrical and mechanical faults. When any fault occurs, the phase and line voltages of the inverters get decreased. This leads to reduction of torque and speed of the motor and hence the operation of induction motor is interrupted. This states the importance for fault diagnosis of T Z-Source inverter fed induction motor to analyse the performance of the drive under faulty conditions. The performance of the induction motor under various faults is verified by MATLAB simulation of a 5 Hp induction motor fed by a high performance ZSI and the simulation results are presented. A comparative evaluation of Z-source and T Z-source topologies is done for the same load torque conditions.

A Three Phases Z-Source Inverter Topology

Now Z-Source inverter is replacing traditional inverter and becoming a research focus. But traditional Z-source inverters bring high voltage stress both in DC input and the Z-source network, which restricts its wide application. In order to solve this problem, a new type Z-source structure with third harmonic injection control strategy is proposed in this paper. The principle and operation models are analyzed. Compared with traditional boost-type Z-Source topologies, the proposed topology offers lower voltage stress, whats more, soft-start strategy can be implemented to suppress the inrush surge arising in the start process. Finally, simulation results demonstrate the good performance of the proposed inverter.

Asymmetrical transformer‐based embedded Z ‐source inverters

Z-source inverters are inverters with buck–boost capability that traditional inverters cannot match. Despite this ability, present Z-source topologies are burdened by some limitations such as chopping input current, high-voltage stress and poor spectral performance at high gain. To improve their performances, a number of asymmetrical transformer-based embedded Z-source inverters are proposed. Through theoretical derivation and experiments, the proposed inverters have been shown to draw a smooth input current and produce a high gain by varying the transformer turns ratio n. The range of variation for n depends on the inverter topology chosen, which in turn depends on the application under consideration.

Z‐source‐based isolated high step‐up converter

Continuous input currents and high step-up ratios are desired from the dc-dc converters that work with renewable energy sources such as photovoltaic panels and fuel cells. Most dc-dc converters use transformers to have high step-up ratios. There is another type of converters that use coupled inductors, but they need to operate at high duty cycles to increase the gain. These converters suffer from low efficiency values because of the leakage inductance values and long reverse recovery times of the diodes. A new dc-dc converter based on Z-source topology is proposed in this study. It uses coupled inductors to increase the step-up ratio. Its main features are high step-up ratios, continuous input currents, high efficiency and galvanic isolation between input and output. Simulation and experimental results are given for a prototype converter that converts 25-400 V dc at 300 W with over 91% efficiency.

Three-phase Z-source power supply design

Z-source converter configurations make it possible to overcome intrinsic limits present in conventional ac–dc and dc–ac converters. A typical three-phase inverter cannot supply output voltages greater than the voltages at its input; in the same manner, a typical three-phase boost rectifier cannot supply output voltages lower than input voltages. Using Z-source topology permits overcoming both these limits. In fact, a Z-source boost rectifier can theoretically either step-up or step-down the output voltage to any desired value starting from the conventional three-phase diode bridge rectifier output voltage level. In addition, it presents intrinsic immunity to shoot-through states, resulting in improved reliability of the entire system. In this study, attention is focused on the mathematical modelling of a three-phase Z-source boost rectifier for power factor correction power supply applications; using such a topology as first-stage converter allows designing the second-stage converters with the same voltage constraints of single-phase units.

단상 Quasi Z-소스 동적전압보상기(DVR)

본 논문에서는 새로운 quasi Z-소스 토폴로지의 동적전압보상기를 제안한다. 제안된 시스템은 quasi Z-소스 PWM 교류-교류 컨버터를 기반으로 하고 있으며, 입력단과 출력단은 공통 접지이고, 연속적인 입력전류 모드(CCM)로 동작하는 특징을 가지고 있다. 전원 전압의 sag와 swell을 검출하기 위하여, 피크치 전압 검출기법이 사용되었으며, 제안된 시스템의 동작 원리를 제시하고 회로 해석을 하였다. 제안된 시스템은 30% 전압 swell과 60%의 심한 전압 sag가 발생하여도 과전압과 부족전압에 대하여 순간적으로 보상을 하였으며, 부하전압을 정현파의 정격전압으로 유지할 수 있었다. PSIM 시뮬레이션과 실험결과를 통하여 본 연구의 타당성을 입증하였다. This paper deals with a single-phase dynamic voltage restorer(DVR) with a quasi Z-source topology. The proposed system based on a single-phase quasi Z-source PWM ac-ac converter which have features such as the input voltage and output voltage are sharing ground, and input current operates in continuous current mode(CCM). For the detection of voltage sag-swell, peak voltage detection method is applied. Also, the circuit principles of the proposed system are described. During the 60% severe voltage sag and 30% voltage swell, the proposed system controls the adding or missing voltage and maintains the rated voltage of sinusoidal waveform at the terminals of the critical loads. Finally, PSIM simulation and experimental results are presented to verify the proposed concept and theoretical analysis.