Quasi Z-source Network Research Articles

Switching Strategy to Reduce Inductor Current Ripple and Common Mode Voltage in Quasi Z-Source Ultra Sparse Matrix Converter

This paper aims to reduce the ripple current in the inductor used in a Quasi Z-source Ultra Sparse Matrix Converter (QZSUSMC). The main limitations of the conventional Ultra Sparse Matrix Converter (USMC) are limited voltage gain <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$(\leq 0.866)$</tex-math></inline-formula> and high common mode voltage (CMV). By integrating a quasi Z-source network in the DC link of USMC and providing a shoot-through (ST) state in a switching cycle, a voltage gain greater than unity can be achieved. Inductors are magnetised during the ST state and demagnetized during the nonshoot-through (NST) state. Hence with a proper arrangement of the ST and NST states, ripple in the inductor current can be minimised. In the proposed modulation, the total ST time is divided into six unequal parts and arranging them to minimize the inductor ripple current. in addition to it, proposed method also offers proper switching arrangements by using active vectors to attenuate peak-peak common mode voltage (CMV). As compared to the earlier reported methods, the proposed method produces a better inductor current ripple and a reduced peak of the CMV. Simulation and developed testing circuit results show the effectiveness of the proposed method.

Modeling and analysis of the LC filter-integrated quasi Z-source indirect matrix converter for the wind energy conversion system

A Quasi Z-Source Indirect Matrix Converter (QZSIMC) is proposed in this paper for Permanent Magnet Generator (PMG) based Direct Drive Wind Energy Conversion Systems (DDWECS) to enhance the voltage transfer ratio and also to control the output voltage under various loading conditions. The QZSIMC comprises three Quasi Z-Source (QZS) networks connected between PMG and load through a three-phase Indirect Matrix Converter (IMC). Two different PWM control techniques such as Carrier Based Pulse Width Modulation Technique and Modified Space Vector Pulse Width Modulation Technique are proposed to analyze the performance of QZSIMC. By changing the shoot through time period, the duty ratio of quasi Z-Source network can be increased which in turn increases the boost factor of both QZSIMC without affecting the efficiency of the converter. A closed-loop control system has also been designed to sustain constant parameters at the output. The proposed QZSIMC for PMG based DDWECS along with two different PWM Control Schemes are to be modeled using MATLAB/SIMULINK environment. To validate the simulation results, a 1 kW, 415 V, 50 Hz experimental setup with an FPGA SPARTAN-6 processor has been developed in the laboratory for QZSIMC and the results are investigated based on the parameters such as output voltage, output current, Switching Stress, Boost Factor, inductor current, capacitor voltage, Total Harmonic Distortion.

Improved Quasi-Z-Source High Step-Up DC-DC Converter Based on Voltage-Doubler Topology.

The step-up DC-DC converter is widely used for applications such as IoT sensor nodes, energy harvesting, and photovoltaic (PV) systems. In this article, a new topological quasi-Z-source (QZ) high step-up DC-DC converter for the PV system is proposed. The topology of this converter is based on the voltage-doubler circuits. Compared with a conventional quasi-Z-source DC-DC converter, the proposed converter features low voltage ripple at the output, the use of a common ground switch, and low stress on circuit components. The new topology, named a low-side-drive quasi-Z-source boost converter (LQZC), consists of a flying capacitor (CF), the QZ network, two diodes, and a N-channel MOS switch. A 60 W laboratory prototype DC-DC converter achieved 94.9% power efficiency.

New high step-up DC-DC converter with quasi Z-source network

New high step-up DC-DC converter with quasi Z-source network

Research on a new space vector modulation strategy of the improved quasi-Z source four- leg matrix converter

In order to overcome the low voltage utilization of matrix converter, a new quasi-Z source network is introduced into matrix converter (QZS-4LMC), and a new improved dual space vector modulation strategy is proposed. Firstly, the improved QZS-4LMC topology and its working principle are analyzed. On this basis, a dual-space vector modulation strategy based on the action time allocation of shoot-through zero vector is proposed. Then, a detailed simulation is carried out on the Matlab/Simulink simulation platform, and a TMS320F28335 prototype controlled by FPGA and DSP is designed for preliminary experimental verification. Compared with the traditional quasi-Z source three-phase four-bridge matrix converter, the feasibility and superiority of the improved quasi-Z source topology and control strategy are verified.

Implementation and Analysis of Grey Wolf Optimization Technique for PV Fed Switched Coupled Inductor Quasi Z-Source Cascaded Multilevel Inverter

A new type of photovoltaic (PV) fed cascaded multilevel topology is proposed in this work. The proposed topology is an integration of Switched Coupled Inductor (SCL) quasi Z-Source network (qZS) to Cascaded Multilevel Inverter (CMI). In order to extract maximum power with high tracking efficiency under various conditions from the PV system, Grey Wolf Optimization (GWO) algorithm is implemented in the proposed topology. The main aspect of GWO is to control the duty cycle through iterations for better performance. The GWO has the potential to achieve global peak under any climatic conditions. The iterations are done in three steps mainly hunting, encircling for prey and, attacking prey. To prove the effectiveness of GWO, its performance is compared with traditional Perturb &amp; Observe (P &amp; O) MPPT technique. The proposed technique is implemented, tested for various Partial Shading Conditions (PSC) using MATLAB/ Simulink results are verified with experimental set up of 1 kW by utilizing My-RIO embedded FPGA processor board.

A fuel-cell/battery hybrid DC backup power system via a new high step-up three port converter

In this paper, a fuel-cell (FC)/battery hybrid direct-current (DC) backup power system is proposed for high step-up applications. This system is composed of a newly developed non-isolated three-port converter, which achieves a high voltage gain by taking the advantage of a quasi Z-source network and an energy transfer capacitor. After analyzing the converter, a comprehensive comparison study and a design procedure are provided. Moreover, the controllers regulating the source power levels while smoothing the FC power profile according to the proposed energy management strategy (EMS) are designed based on the developed small-signal model of the proposed converter. Both hardware and controller design procedures are validated through the PSIM model of the whole system. As a result, it is shown that the proposed system can effectively couple FC and battery while transferring their energies to a high voltage DC bus according to the offered EMS.

A new quasi Z-source network applied to direct matrix converter

A new quasi Z-source network applied to direct matrix converter

Direct matrix converter based on improved quasi‐Z source network

This study proposes a three-phase direct matrix converter (DMC) topology based on an improved quasi-Z source (QZS) network. The proposed topology shows the following features: (i) Improve the voltage transmission ratio of traditional DMC. (ii) The voltage and current on the output side can be affected by the input side to the minimum, which minimises the harmonic content of the output current. (iii) Due to the existence of the improved QZS network, the three bidirectional switches of each output phase bridge arm are turned-on at the same time, which improves the reliability of the system. (iv) The improved QZS network has an input LC filter function, and no additional filter circuit is required on the input side. This study analyses the topological structure of the improved QZS-DMC and elaborates its boost working principle. On this basis, an improved dual space vector modulation strategy with shoot-through zero vector is proposed, which can effectively reduce the loss of the switch tube and improve the output waveform quality of the converter. Simulation and experimental results verify the proposed topology and strategy.

A new space vector modulation technique for quasi Z-source B4 inverter

A Quasi Z-Source (qZS) network has been utilized in a B4 inverter topology to provide voltage boosting effect by turning on the upper and lower switches simultaneously which is known as zero shoot-through states. However, the design of a qZS B4 inverter is not as straightforward as adding a qZS LC impedance network to the front-end of a B4 inverter. This is because there is no zero vectors available in a B4 inverter topology to insert the shoot through zero states, as in the case of a B6 inverter. This paper proposes a new Space Vector Modulation (SVM) technique for a qZS B4 inverter. Additional zero vectors have been appropriately added and distributed in the proposed SVM to avoid altering the existing volt-sec per switching cycle for the existing active vectors. The voltage vectors switching placement is carefully designed in order to enable the voltage boosting effect for this topology without altering the initial output voltage. In addition, an approach to compensate the DC-link voltage ripple has also been taken into consideration in its initial calculation to achieve balanced output voltage. The performance of the proposed modulation technique is verified using MATLAB/Simulink. It is shown that by using the proposed modulation technique, there is an overall improvement on the line to line output voltage where by it is able to produce balanced output voltages for the three-phase loads with or without boosting effect.

IMPLEMENTATION OF FRACTIONAL PI CONTROLLER FOR OPTIMAL SPEED CONTROL OF INDUCTION MOTOR FED WITH QUASI Z-SOURCE CONVERTER

Recently, Induction motor are extensively used in many application and are present in almost all production processes. Trouble in induction motor results in reducing the machine speed, large amount of intake of current and operational disaster which causes economic and human losses. To have a better efficiency in induction motor, this proposed work focuses with the efficient control technique. The objective of this proposed work is to find effective technique to sustain at a steady state and dynamic analysis and to determine the parameters and performance of the machine. Quasi Z-source network is employed to boost up the source voltage and transformation from AC to DC is performed. To drive the induction motor at a standard speed, some controllers were analogized and the well performing fractional PI controller was chosen to perform at a top notch level. Analogizing fractional PI controller with other controllers like PI controller, and fuzzy logic controller, Fractional PI controller performs well in solving the problem faced by other controllers. The experimental result shows the torque, rise time, settling time, and peak time are measured and obtains the better result as compared with the PI, Fuzzy and FO-PID approach. The torque results to 1.1Nm on proposed method; steady state error is reduced from 2.4 to 1.1 and the peak time settling time and rise time is reduced near 1.93 to 0.85 ranges of settling time; 1.66 to 0.79 of peak time; 1.55 to 1.62 of rise time. The entire system is manipulated using DSPIC and the simulation results are performed using MATLAB.

Design and analysis of a novel quasi Z source based asymmetric multilevel inverter for PV applications

A novel Quasi Z source (QZS) based Asymmetric Multilevel Inverter for Photovoltaic application is proposed in this paper. It consists of an Impedance source-based dc-dc converter and Asymmetric Multilevel Inverter (AMLI). QZS network can buck/boost the input DC voltage eliminating separate DC-DC boost converter. MLI topology with reduced switches and DC input provide high quality output with large levels. DC input magnitude of the inverter is based on an algorithm. The system ensures high voltage gain, low switching stress, lessened gate circuitry, high reliability and better harmonic profile. Low THD values ensures reduced filter size and hence cost. The theoretical concepts and parameter design of the proposed topology is illustrated in detail. The performance analysis is verified using Matlab/Simulink environment.

Performance Analysis of Dual Space Vector Modulation Technique-Based Quasi Z-Source Direct Matrix Converter

—This article proposes a dual space vector control strategy for quasi Z-source direct matrix converter (QZSDMC) which is made up of quasi Z-source network coupled to a matrix converter (MC). It ensures effective regulation of voltage regulation range and overpowers the voltage transfer ratio restrictions of conventional matrix converter. The QZSDMC can afford buck boost operation by observing the bidirectional operation capability and shoot through duty ratio. Also, it provides continuous input current and eliminates the need for input LC filter. First, the principle of operation of the proposed QZSDMC is presented in detail. Then, a dual space vector pulse width modulation technique for QZSDMC has been analyzed along with the distribution of shoot through time in the zero vector. The proposed topology with the control strategy has been simulated in MATLAB/SIMULINK and the simulation results are verified with the experimental results from the basic prototype machine controlled by FPGA.

Research on Control Strategy of Quasi-Z Source Network DC/DC Converter for Fuel Cell Vehicle

DC/DC converter for fuel cell vehicles is required to operate in high voltage gain and wide voltage range conditions, which traditional boost converter is difficult to meet. In this paper, the control strategy of a quasi-zsource boost converter used in fuel cell vehicles is studied. Based on the small signal dynamic modeling method, the double-closed-loop control strategy of voltage and current is adopted. In addition, the input voltage feedforward compensation control strategy is adopted to improve performance in rejecting Input voltage disturbance. A 400W prototype is built for experimental verification. Experimental results show that the proposed input voltage feedforward compensation strategy and double- closed-loop control strategy of voltage and current effectively improve the system dynamic response speed and robustness.

Comparative Analysis of Symmetrical/Asymmetrical Quasi Z-Source Cascaded Multilevel Inverter with Alternative Phase Opposition Disposition Technique

Abstract This paper presents a detailed comparative analysis between Symmetrical and Asymmetrical Quasi Z-Source Cascaded Multilevel Inverter (QZS-CMI). The comparative analysis investigates for boost operation in both Symmetrical and Asymmetrical System. Analysis is done based on the achieved input current, capacitor voltage of the upper capacitor and parallel capacitor and the two inductors current of DC link (Quasi Z-Source network) which is combined with H-bridge. In Asymmetrical QZS-CMI, the input voltage for three DC sources are given in the ratio of 1:3:9, i. e. the system is designed for 27 level. Asymmetrical QZS-CMI is new system and proposed in this paper for comparative analysis with Symmetrical QZS-CMI. An advanced optimal Alternative Phase Opposition Disposition (APOD) technique is developed and implemented. Symmetrical system has high boosting capability of output voltage, reducing the switching losses, high voltage gain and lower spikes in switching voltage. The comparative study is done and results are verified with Experimental 250 W prototype model and also verified by using MATLAB/ Simulink.

Modeling and simulation of quasi-Z-source indirect matrix converter for permanent magnet synchronous motor drive

This paper aims to use a three-phase quasi-Z-source indirect matrix converter (QZSIMC) to expand the voltage gain for application in a Permanent Magnet Synchronous Motor (PMSM) drives. In this converter, a unique quasi-Z-source network (QZSN) connects the three-phase input voltage to conventional indirect matrix converter (IMC) in order to boost the supply voltage for PMSM because of limited voltage gain of IMC. Dual space vector modulation (SVM) is utilized to control the QZSIMC. The amplitude of output voltage for quasi-Z-source network is raised by the shoot-through of the rectifier stage, so the system voltage gain becomes greater. Through selecting the optimized value of shoot through duty ratio (&lt;em&gt;D&lt;/em&gt;) and modulation index of the rectifier stage (), the drive system can automatically regulate the output voltage of QZSIMC during conditions of voltage sag , step change in load torque and reference speed change when the required voltage gain of QZSIMC is more than 0.866 depending on input voltage and required output voltage.The vector control technique based on closed loop speed control is proposed to control speed of the motor from zero to rated speed which is combined with the proposed converter to obtain the motor drive. The simulation results with MATLAB /Simulink 2015 are obtained to validate performance of PMSM drive.

Finite set model predictive control method for quasi‐Z source inverter‐permanent magnet synchronous motor drive system

In this study, a finite set model predictive control method is proposed for the quasi-Z source inverter-permanent magnet synchronous motor drive system. In the proposed method, the control variables of quasi-Z source network and motor are controlled uniformly, which can avoid the conflicts between the shoot-through duty cycle and the inverter modulation coefficient during the dynamic adjustment process in traditional two-stage control method. Due to the particularity of the motor connected to the quasi-Z source inverter, a power compensation control method is used to obtain the inductor current reference value. Whether the shoot-through vector is chosen as the optimal vector is determined by the inductor current, and the influence of undershoot phenomenon of capacitor voltage, which results from the non-minimum phase characteristics of quasi-Z source inverter, is avoided. Steady-state, dynamic, and input voltage dip experiments are performed on a quasi-Z source inverter-permanent magnet synchronous motor drive system. The experimental results verify the feasibility of the proposed predictive control method. Besides, compared with traditional two-stage control method, the proposed method has quicker response speed and stronger anti-disturbance ability.

Quasi-Z-Source Indirect Matrix Converter Fed Induction Motor Drive for Flow Control of Dye in Paper Mill

This paper describes a flow control of the dye in the paper mill with the quasi-Z-source indirect matrix converter (QZSIMC) fed induction motor drive. More than a decade the voltage-source inverter (VSI) and current-source inverter (CSI) have been used to control the speed of the induction motor, which in turns controls the flow of dye. Recently, the matrix converter (MC) has been an excellent competitor for the VSI or CSI for its compactness. The voltage transfer ratio of the VSI, CSI, and MC has been limited to 0.866. Thus, the efficiency of these converters is less. To improve the voltage transfer ratio the quasi-Z-source network (QZSN) is to be used between voltage source and indirect MC (IMC). The modification in the shoot-through duty ratio of the QZSN varies the voltage transfer ratio greater than 0.866. Different voltage transfer ratios are needed for different voltage sag conditions. For a variation of the duty ratio of the QZSN, the fuzzy logic controller has been presented. To control the IMC vector control with space vector modulation has been presented. This paper proposes the implementation of QZSIMC adjustable speed drive for the flow control of dye in paper mill during different voltage sag conditions. A 4-kW prototype has been built and the effectiveness of the proposed system is verified with simulation results and experimental setup. Simulation is done in MATLAB, Simulink platform. Experimental setup is done with the aid of a TMS320F2812 (Texas Instrument) processor. The experimental results validate the maintenance of the speed of an induction motor at the set condition, thus controlling the perfect flow of dye in paper manufacturing technology.

QUASI Z-SOURCE NETWORK BASED CONTROL SCHEME FOR FSTP BLDC MOTOR

The paper proposes a novel four switch three phase BLDC motor control scheme which boosts the voltage level, extends the range of speed as well as reduces output torque ripple. The additionally partial circuits of quasi Z-source network and the bridge arm of four-switch inverter constitute the quasi Z-source converter. During the operation of motor, shoot through states are inserted. Then the input voltage of inverter increases and the performance of motor can be markedly improved. The dynamic performance of current is influenced and the speed is limited, for the irregular dc-link voltage utilization in the control of four-switch three-phase (FSTP) BLDC motor. This project presents a novel topology, which combines quasi Z-source converter and FSTP drive circuit. The drawbacks of FSTP BLDC motor are analyzed, the control methods of each mode in quasi Z-source four-switch three-phase (QZFSTP) topology are illustrated. Simulations for QZFSTP BLDC motor were constructed in MATLAB/Simulink circumstance. We can provide an alternate strategy to control BLDC motor by using Four Switch Three Phase inverter. FSTPI helps reduction in switching losses, gate drive requirements, circuit cost and computational time. At low power application, FSTPI fed BLDC motor drives are more suitable than SSTPI (Six Switch Three Phase Inverter). Also reconfiguration of these three leg inverter to FSTPI, in case of switch or leg failure can be done. In proposed system losses are minimizing due to FSTPI because there is reduction in switching losses and also due to Quasi Z-source Inverter output voltage is boosting hence output results were better. To overcome the ripple in torque and distortion in current the QZFSTP BLDC motor control scheme is proposed.

Multi-Stage Cascaded Quasi Z-Source Inverter System for Renewable Energy Applications

Multi-stage cascaded quasi Z-source inverter (qZSI) features a lesser shoot-through duty ratio for the same boost factor of the input voltage, but the traditional qZSI has the disadvantage of possessing increased shoot-through ratio and very high component stress at the same voltage boost factor. The whole idea of this work is to present a multi-stage cascaded quasi Z-source inverter for application to photovoltaic power system. Three-stage cascaded qZSI is obtained by adding two diodes, two inductances and three capacitances to the traditional quasi Z-source network. Due to the cascaded structure and qZSI topology, the proposed system acquires all the advantages of impedance inverter that can realize boost/buck function in a single-stage with improved reliability, lower component rating, constant DC current from source and good power quality. Besides, the three-stage cascaded solution the shoot-through duty cycle by 25% at the same voltage boost factor. The topological characteristics of three-stage cascaded qZSI system is analysed and operating principles are discussed. An experimental prototype is built to test the three-stage cascaded qZSI module. Simulation and experimental results are presented to demonstrate the validity of the proposed system.