Quasi Z-source Converter Research Articles

Enhanced modelling and control strategy for grid-connected PV system utilizing high-gain Quasi-Z source converter and optimized ANN-MPPT algorithm

Enhanced modelling and control strategy for grid-connected PV system utilizing high-gain Quasi-Z source converter and optimized ANN-MPPT algorithm

Modeling and control of a new multi-port converter for hybrid energy system integration

This research introduces a new topology called the quasi-Z-source integrated isolated multiport bidirectional resonant DC-DC converter. The aim is to achieve cost-effective and efficient multi-directional power flow between photovoltaic (PV), battery/supercapacitor, and DC loads. The proposed topology ensures uninterrupted power supply to the loads and supports reverse power transfer through its bidirectional power flow capability. By combining quasi z-source and H-bridge resonant converters with an existing switch, a four-port converter is achieved without the need for separate converters or additional switches. The high-gain quasi z-source converter reduces the required voltage ratings of the battery and supercapacitor packs while enabling the utilization of a high-frequency transformer (HFT) with a low turns ratio. Isolation between the ports is achieved using a secondary center-tapped HFT equipped with a controlled full-wave rectifier on the secondary side, allowing bidirectional power flow. A power flow management system and corresponding control scheme are proposed to optimize the system's performance. The proposed system's performance is evaluated under various operating conditions, demonstrating its effectiveness in power flow management and overall efficiency. The results confirm the feasibility and effectiveness of the proposed system.

Soft switching high step-up three-level boost DC-DC converter with Quasi Z-source for Photovoltaic application

A three-level Boost DC-DC converter is proposed in this paper. Quasi Z-source converter acts as an auxiliary circuit to create soft switching condition for all active elements. Consequently. The converter efficiency is very high. Using a three-level structure in the proposed converter causes the maximum voltage stress across the semiconductor devices is limited to half of the output voltage. The converter has a high voltage gain and a small number of elements. The converter is analyzed with details in all operating modes. Furthermore, the experimental results are obtained to prove the converter performance based on the theoretical considerations.

ANN and ANFIS Based Control Approaches for Enhanced Performance of Solar PV Driven Water Pumping Systems Employing Quasi Z-Source Converter

ANN and ANFIS Based Control Approaches for Enhanced Performance of Solar PV Driven Water Pumping Systems Employing Quasi Z-Source Converter

An extendable multicell quasi Z‐source converter topology using an active switched network

SummaryThis paper proposes a new extendable multicell topology based on the conventional quasi‐Z‐source converter (QZSC). The proposed topology has a multicell scheme and employs an active switched capacitor/inductor (ASC/SL) network. Therefore, it is entitled extended multicell ASC/SL QZSC (EMc‐ASC/SL‐QZSC). The proposed topology is augmented by cascading a modular cell consisting of two capacitors, an inductor, and a diode. The EMc‐ASC/SL‐QZSC offers significant advantages over existing QZSC‐based configurations. It has a high boosting capability that results in a wider output voltage range while simultaneously reducing voltage stress on capacitors and switching devices, all without losing voltage gain. Furthermore, this topology effectively reduces input current ripple, which contributes to a smoother charging current profile for capacitors, reducing electromagnetic interference (EMI) and improving overall efficiency. The practicality and performance of the EMc‐ASC/SL‐QZSC topology are comprehensively assessed through extensive numerical simulations and experimental verification, utilizing a laboratory‐built prototype.

Quasi Z-Source Converter Fed Inverter with Active Switched Network

This paper presents a quasi-Z source converter fed inverter with active switched networks. The converter topology is implemented with the help of capacitor, inductor and diodes connected in such a manner to improve voltage gain. A novel active switching network is developed to improve the harmonic performance of converter. Thus, network designed uses a combination of active switches and diodes to reduce the voltage and current ripple in the quasi-Z source converter. The performance of proposed converter is evaluated using a simulation. The results proves that the proposed converter can achieve a better harmonic performance than a conventional converter.

A Novel Solid-State Transformer with Improved Flyback Converter Equipped with Quasi Z-Source Converter for Medium-Voltage Utility Grid

This paper introduces an enhanced solid-state transformer topology for a medium-voltage (MV) utility grid. The main objective of the current study is to develop an improved flyback converter equipped with a quasi z-source converter (qZ_iFC) having a high-voltage conversion capability for the integration of low-input voltage to the DC link of an MV modular multilevel converter (MMC). The system integrates the quasi z-source and flyback converters by operating their existing switches complementary. Furthermore, the high-gain qZ_iFC allows for a reduction in the rated voltage of the input, as well as the use of a high-frequency transformer (HFT) with a unity turns ratio that provides galvanic isolation between the input and the output ports. Thus, using an HFT just for isolation purposes without voltage gain improves the system efficiency. In addition, a controller for (i) qZ_iFC which is regulating complementary switches to prevent the shoot-through current from reaching the HFT resulting in saturation; and (ii) a controller for MMC to produce MV-level AC voltage for loads are suggested. The performance of the proposed system was evaluated for several operating conditions. Results show that the proposed SST smoothly performs the power flow between the ports during steady-state and transient conditions. The power flow capabilities and efficiency values validate the viability and effectiveness of the proposed system.

Operation and Control of a Quasi Z-source Converter in a Renewable Hybrid Microgrid

The power sharing need and operational reliability of a renewable hybrid microgrid are addressed in this study. A hybrid microgrid allows for the flexible incorporation of renewable energy sources, overcoming the limitations of AC and DC microgrids in terms of conversion losses and efficiency. To ensure optimal system performance, an interlinking converter (IC) is necessary for the seamless transmission of electric power between the two subgrids while keeping a stable DC bus voltage and appropriate AC sub-grid frequency. In this study, a Quasi Zsource converter (qZSC) with integrated boost capability is introduced as an IC in a PV-Wind based hybrid microgrid. Also, an adaptive dual loop based-PI (ADL-PI) control is proposed which maintains a constant peak DC-link voltage and supports maximum power point tracking while improving the system's overall stability. The proposed system and control approach are assessed using MATLAB/Simulink, and the results indicate its efficacy under various scenarios.

An Improved Quasi-Z-Source Boost DC-DC Converter Using Single-Stage Switched-Inductor Boosting Technique

A modified single-stage Quasi-Z-Source (QZS) boost DC-DC converter using a single MOSFET switch with a single-stage switched-inductor (SI) network is proposed in this paper. The DC-DC converter proposed in this study provides an extra voltage gain compared to the traditional QZS DC-DC converter. An additional capacitor and diode circuit are added to the existing QZS converter to decrease the voltage stress on the MOSFET switch. Therefore, compared to the traditional QZS boost converter, the proposed Modified QZS (MQZS) converter provides large voltage gain under a low duty ratio, less voltage stress, and continuous input current. Moreover, the reliability and the conversion efficiency can be increased. The derivation of the proposed MQZS converter and its operation, selection of parameters, and comparison with another similar converter are discussed in this paper. Lastly, the simulation and experimental results are illustrated to prove the notional deliberations of the proposed MQZS converter.

Common Ground Quasi-Z-Source Series DC–DC Converters Utilizing Negative Output Characteristics

This article presents a general method to obtain the improved common ground quasi-Z-source series dc–dc converters. Utilizing the negative output characteristic of the quasi-Z-source converter (QZSC), the output voltage of the improved converter is the sum of the input voltage and the output voltage of the original QZSC, which means that part of the energy is directly supplied by the input voltage source without passing through QZSC. Therefore, compared with the original QZSC, the proposed improved converter has advantages such as lower voltage stress, lower current stress, higher voltage gain, and higher efficiency. More importantly, all these improvements are obtained with no obvious drawback. No additional component is required, the input and output remain common ground, and if the input current of the original converter and the load current are continuous, the input current of the improved converter is also continuous. In order to prove the feasibility of the proposed method, first, the improved converters of three existing QZSCs are obtained. Then, the operation principle, parameter design, and comparison are introduced in sequence. Finally, the above analyses are verified by simulation and experiment results.

Design of quasi‐Z source converter for vehicle to vehicle to battery charging application

AbstractThe Quasi‐Z‐source converter (QZSC) is the favorite dc‐dc converter that can be applied to applications like EV battery charging, microgrid, distributed generator, etc. QZSC is the modified version of the Z‐source converter (ZSC) which has the additional qualities of uninterrupted input current and a broad range of input voltage over ZSC. In this article, QZSC is especially developed for the dc‐dc like vehicle‐to‐vehicle (V2V) battery charging application. Due to the availability of shoot‐through conditions, QZSC overcomes the burden of the additional dc‐dc booster, unlike a two‐stage converter. This additional benefit of the shoot‐through condition makes QZSC more worthy than a conventional converter. The elaborated design analysis of the QZSC is presented in this article which found reduced voltage stress across one of the capacitors, unlike the traditionalistic impedance source converter. The hardware prototype of QZSC is developed and experimental results are obtained. The experimental results are verified by using simulation and theoretical results. Experimental results suggest that the QZSC converter concept could be most suitable for the V2V battery charging applications. Simulation results are obtained for QZSC by using a matrix laboratory.

WITHDRAWN: A novel hybrid DC/DC and modified quasi Z-source converter for enhanced voltage gain

Abstract This paper proposes the use of a novel non-isolated high gain DC/DC converter using an amalgamation of the switched-capacitor networks and modified quasi Z-Source. The suggested converter has an appropriate number of components, but its capacitors and semiconductors meet the low voltage stresses. Besides, the new converter's voltage gain is substantially higher at lower duty cycles, when compared with other converters. The new converter's efficiency is 90.488% and the gain value is 5.6. Furthermore, the steady-state analysis is specified with the design of passive components. Finally, simulation results are given in MATLAB for validation of the theoretical analysis.

Partly isolated three‐port DC–DC converter based on impedance network

This study proposed a novel partly isolated three port converter (PITPC) based on a quasi-Z source converter for photovoltaic applications. Compared with the conventional quasi-Z source converter, the proposed DC–DC converter has dual input sources and uses the switched capacitors and coupled inductor techniques, helping the converter to gain a high voltage. To achieve the power flow control, the proposed converter uses only three power switches with low voltage stress and it is developed for hybridising photovoltaic panels, rechargeable batteries and isolated loads. For this purpose, the proposed PITPC can be easily reconfigured into dual-input single-output, single-input dual-output and single-input single-output modes; so it can even operate when the photovoltaic panel fails to provide energy to the load. Moreover, the study thoroughly discusses various converter operating modes and provides explanations and necessary relationships for circuit operations. The study also explains the control strategy as well as the pulse width modulation waveforms for the proposed converter. Simulation results from MATLAB/Simulink examine the proposed topology performance. The experimental results confirm the advantages claimed for the proposed converter; the results also show a well-distributed efficiency curve and a peak of 96.3%.

LC Impedance Source Bi-Directional Converter with Reduced Capacitor Voltages

This paper proposes an LC (Inductor and Capacitor) impedance source bi-directional DC–DC converter by redesigning after rearranging the reduced number of components of a switched boost bi-directional DC–DC converter. This new converter with a conventional modulation scheme offers several unique features, such as a) a lower number of components and b) reduced voltage stress on the capacitor compared to existing topologies. The reduction of capacitor voltage stress has the potential of improving the reliability and enhancing converter lifespan. An analysis of the proposed converter was completed with the help of a mathematical model and state-space averaging models. The converter performance under different test conditions is compared with the conventional bi-directional DC–DC converter, Z-source converter, discontinuous current quasi Z-source converter, continuous current quasi Z-source converter, improved Z-source converter, switched boost converter, current-fed switched boost converter, and quasi switched boost converter in the Matlab Simulink environment. MATLAB/Simulink results demonstrate that the proposed converter has lesser components count and reduced capacitors’ voltage stresses when compared to the topologies mentioned above. A 24 V to 18 V LC-impedance source bi-directional converter and a conventional bidirectional converter are built to investigate the feasibility and benefits of the proposed topology. Experimental results reveal that capacitor voltage stresses, in the case of proposed topology are reduced by 75.00% and 35.80% in both boost and buck modes, respectively, compared to the conventional converter circuit.

Design and analysis of Impedance Source based Asymmetric Inverter for PV application

A novel Impedance source seven level Asymmetric Multilevel topology for PV system is presented here. It comprises of a Quasi Z source network and Asymmetric Multilevel Inverter (QZ-AMLI) to synthesize better quality output with low THD. Quasi Z Source Converter (QZSC) with large voltage gain provides a positive boost voltage to an asymmetric multilevel inverter. Asymmetric structure offers large output levels with a smaller number of switches and input sources. QZS network parameters provide a regulated DC supply to the Asymmetric Multilevel inverter (AMLI). DC input magnitude of the inverter is decided by an algorithm. Switching signals are applied in proper sequence to generate required magnitude at the AC output. Regulated DC output voltages of 16V and 32V are obtained at the output of QZSC1 and QZSC2. 7 level inverter output with a magnitude of 48V is obtained by simulation using Matlab /Simulink. The system ensures lower switching losses, reduced gate drive circuitry and improved harmonic profile. Reduced switch and filter requirements lessen the cost of the system.

A New Coupled Inductor Nonisolated High Step-Up Quasi Z-Source DC–DC Converter

In this article, a new nonisolated high step-up quasi Z-source (QZS) dc–dc converter with coupled inductor techniques is presented, which is suitable for renewable applications. The main advantages of the proposed topology are continuous input current, common ground between load and input dc source, low normalized voltage stress on the semiconductors (switch/diodes), and low total voltage stress on devices compared to the conventional QZS converter. However, increasing the turns ratio value of the coupled inductor windings not only limit the duty cycle but also leads to decrease the voltage stress on switch/diodes and increase the output voltage level. The operating performance of the proposed converter, theoretical analysis and comparison between the proposed converter and other published works (i.e., QZS converters) are provided. Finally, one prototype at 500 W is built and tested, which shows experimental results and theoretical analysis verify each other well.

A Modified Partial Power structure for Quasi Z-Source Converter to Improve Voltage Gain and Power Rating

Employing partial power processing (PPP) technique for quasi Z-source converter (QZSC) a new structure of the converter is presented. Using PPP technique although eliminates electrical insolation, but permits reducing voltage and current stress at the semiconductors, if compared with full power proposals. In this work, two PPP structures are discussed: A first one, similar to the basic topology, where the output voltage of the power converter is in series with the input voltage; and a second one, where the output is in series with the capacitor of the QZSC. This minor modification, which requires no extra elements, improves the power rating, voltage gain, and requires a lower transformation ratio. An experimental prototype of the proposed converter has been tested and the results are compared with other implementations, permitting to validate the theoretical analysis as well as the advantages that this proposal provides.

Analysis and Control of a New Dual-input Impedance-based DC–DC Converter for Hybrid PV-FC Systems

A new dual-input DC-DC converter based on quasi-Z source converter is proposed in this study. This converter is a suitable option for efficiently interfacing two energy sources with a ...

A Developed Structure for DC–DC Quasi-Z-Source Converter with High Voltage Gain and High Reliability

In this paper, a developed structure for DC–DC quasi-Z-source (QZS) converters is proposed. First, the proposed two-stage structure is presented and analyzed. Then, the proposed structure is extended to [Formula: see text] stages and its relations are calculated. Compared with other conventional structures, the proposed structure has higher voltage gain and higher reliability. The proposed topology is suitable for high power applications. To have the correct performance of conventional QZS converter, all impedance network elements must be intact. In the case of small failure in one of the elements, the operation of the whole system is disrupted. The proposed structure has high reliability because when one stage fails, the fault management system separates that stage from the other stages and the remaining stages continue to transmit power. In this paper, in addition to analyzing the operation of the proposed converter in different operating modes, calculations of voltage gain, voltage stresses across capacitors and reliability analysis are also presented. Reliability is calculated according to well-known Markov model. Moreover, a comprehensive comparison in terms of voltage gain and reliability is made between the proposed converter and the other conventional structures. Also, the rating values of inductors and capacitors are designed. Finally, experimental and simulation results are presented by using power system computer-aided design (PSCAD) software to verify the theories.

A Switched Reluctance Motor Drive Based on Quasi Z-Source Converter With Voltage Regulation and Power Factor Correction

Modified quasi Z-source converter (MQZSC) is presented in this paper as a front end converter for the switched reluctance motor (SRM) drive system in order to perform voltage regulation and power factor correction (PFC). Using the MQZSC, magnetization voltage is increased and regulated according to the operation modes and requirements of the drive system; therefore, more power is transferred to the motor in each stroke. The demagnitization port is also decoupled from the magnetization port and boosted further to reduce demagnetization time. The proposed converter like conventional SRM converter has the freewheeling mode of operation. The peak current control (PCC) PFC is integrated into the control system of the front-end converter to reduce total harmonic distortion and enhance the power factor. Also, an angle control is implemented in the SRM drive system to reduce the torque ripple alongside voltage regulation in the front end controller. A software simulation is done to verify the proposed drive system. To demonstrate the abilities of the proposed drive system in practice, an experimental setup is devised in the laboratory to verify the simulation results.