Shoot-through Interval Research Articles

New Modulation for Z-Source Inverters With Optimized Arrangement of Shoot-Through State for Inductor Volume Reduction

In this article, a new modulation method based on space-vector modulation for Z-source inverters is proposed. One modulation method named ZSVM6 is attractive for the use of SiC- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s since it can avoid the body-diode conduction. The proposed modulation is based on ZSVM6 and can reduce the current ripple in the inductor in its impedance source by introducing additional shoot-through intervals to divide the longest active state. The proposed modulation can reduce the current ripple by 44.5% in comparison with that by the conventional ZSVM6 under the same switching frequency. Conversely, the inductance required to achieve the same current ripple can be reduced by the same ratio. The reduction of the inductor volume through the proposed modulation was confirmed experimentally using a prototype of quasi-Z-source inverter and fabricated inductors. The experimental results also confirmed that the inductor size reduction can be achieved without increase in the total power loss of the converter. A harmonics analysis based on the experiments showed that the harmonic components in the current can be increased through the proposed modulation. However, the frequency range of the increased components can be much higher than the control frequency; therefore, its influence on the design of passive components is not severe.

Design and simulation of Dual Z-Source Dual-Input Hybrid 2/3 level inverter

ABSTRACT The 2/3-level hybrid inverters are a combination of three-level Neutral Point Clamped (NPC) inverter and conventional two-level inverter, which has the advantage of both two-level and three-level structures with fewer switches than the NPC inverter. In this paper, a new structure of 2/3 hybrid inverter based on dual-Z-‏source network is proposed. The proposed structure improves the performance of the 2/3-level inverter and increases its independent DC input voltages. The output voltage gain can be obtained by selecting the shoot-through interval appropriately in dual Z-source networks. In addition, shoot-through intervals in Z-source networks allow the inverter to run without dead time, thus increasing the output voltage quality. A modified switching method is presented for the proposed inverter, and the necessary calculations are performed. The proposed structure can be used to connect different distributed generation sources to the load separately from the grid or to the low-pressure network. The performed simulations show the accuracy of the proposed structure.

An Impedance Source Multi-Level Three Phase Inverter with Common Mode Voltage Elimination and Dead Time Compensation

Currently, most electro-mechanical drive systems that require speed control use pulse-width modulated (PWM) variable frequency drives known as adjustable speed drives (ASD). The high switching speeds of the electronics switches are essential for proper operation of the ASD. Common mode voltage (CMV) has its origin in the PWM switching. The CMV increases the stress on the coils and windings, reduces the life of the bearing and, therefore, has a significant impact on motor life cycle. In this paper, a variant of a PWM-based space vector modulation (SVPWM) switching algorithm is proposed to control both the shoot-through intervals and the dead time of the power switches that could be compensated. The proposed algorithm is implemented on a platform consisting of an impedance source network in the DC side of the topology with the purpose of mitigating the CMV and capability of voltage boosting. Since similar methods have achieved a CMV reduction of 1/6 of the DC link voltage so far, in this paper, while surpassing the disturbing current harmonics, the high efficiency is fully accessible. The presented experimental results verify the effectiveness of the proposed approach by slightly increasing the total harmonic distortion (THD) and reducing the converter losses.

Generalized Space Vector Modulation for Ripple Current Reduction in Quasi-Z-Source Inverters

This article proposes a generalized space vector modulation (SVM) strategy for the three-phase quasi-Z-source inverter (qZSI), which can reduce the inductor current ripples by limiting the peaks in different sectors of the vector space. In the conventional ZSVM6 strategy, the shoot-through interval is divided into six equal parts, which is easy to implement. However, the inductor current ripples are not optimized. Generally, larger inductance is required to limit the current ripples, resulting in poor power density. By contrast, the proposed SVM strategy can minimize the current ripple, while maintaining the same total shoot-through time. Although the shoot-through intervals in the proposed SVM strategy are not identical, easy implementation still holds. The generalized strategy can ensure that the inductor current ripples are always smaller than the peak of the inductor discharging current ripple in a switching cycle. The proposed SVM strategy is derived in details and compared with the conventional ZSVM6 strategy. Simulations and experimental tests are presented to verify the effectiveness of the proposed modulation strategy for the inductor ripple current reduction.

Modulation Control of Impedance Inverter to Achieve Constant and Maximum Boosted Output

For the purpose of solar energy conversion, an AC module that functions as a grid-connected inverter after a PV module is needed. ZSI is being used to alleviate a myriad of issues that VSI and CSI have. India has seen a notable increase in adoption of the renewable energy, Various policies and schemes had been proposed in India to focalize on renewable energy sector. The triggering pulses are generated by bringing the input sinusoidal and triangular waves on the same graph. Maximum boosted output and constantly boosted can be achieved through this method just by adjusting its modulation index and shoot-through intervals. An impedance source inverter provided with triggering pulses generated by maximum constant boost control modulation and maximum voltage boosting technique is presented in this paper.

Modulation Techniques for a Modified Three-Phase Quasi-Switched Boost Inverter With Common-Mode Voltage Reduction

In a single-stage buck-boost quasi-switched boost inverter (qSBI), the shoot-through state insertion causes high amplitude common-mode voltage. Consequently, the qSBI becomes less attractive in transformerless photovoltaic (PV) systems. In this paper, a novel space vector pulse-width modulation for a modified qSBI is introduced to reduce the magnitude of common-mode voltage and push the modulation index up to 1. By properly choosing the shoot-through interval time, shoot-through states are considered to be inserted for boosting voltage and also reducing the THD value of the output voltage. The mathematical analysis and operating principles of the converter are discussed and verified through PSIM simulations. Finally, an experimental prototype is validated based on a TMS320F28335 DSP microcontroller and a DE0-Nano FPGA digital control platform.

IGBT Open-Circuit Fault Diagnosis in a Quasi-Z-Source Inverter

In this paper, a fast and practical method is proposed for open-circuit (OC) fault diagnosis (FD) in a three-phase quasi-Z-source inverter (q-ZSI). Compared with the existing fast OC FD techniques in three-phase voltage source inverters, this method is more cost-effective since no ultrafast processor or high-speed measurement is required. Additionally, the method is independent of the load condition. The proposed method is only applicable to Z-source family inverters and is based on observing the effect of shoot-through intervals on the system variables during switching periods. The proposed algorithm includes two consecutive stages: OC detection and fault location identification. When both stages of the OC FD algorithm are done, a redundant leg is activated and utilized instead of the failed leg. The accuracy of the proposed method is confirmed by the experimental results from a low-voltage q-ZSI prototype.

Modulation control of Impedance inverter for Constant Output

For solar energy conversion, an AC module that functions as a grid-connected inverter after a PV module is needed. ZSI is being used to alleviate a myriad of issues that VSI and CSI have. India has seen a notable increase in adoption of the renewable energy, Various policies and schemes had been proposed in India to focalize on renewable energy sector. The triggering pulses are generated by bringing the input sinusoidal and triangular waves on the same graph. Maximum boosted output can be achieved through this method just by adjusting its modulation index and shoot-through intervals. An impedance source inverter provided with triggering pulses generated by maximum constant boost control modulation technique is presented in this paper.

I-Capacitor Voltage Control for PV Z-source System with Enhanced Shoot-through

&lt;span lang="EN-US"&gt;This paper explains an improved capacitor voltage control (i-CVC) by combining with maximum power point tracking (MPPT) algorithm as a control strategy for a single-phase Z-source inverter (ZSI) using photovoltaic (PV) source. The existing CVC based-MPPT control algorithm has a net shoot-through interval which should be inserted in the switching waveforms of the inverter to produce maximum power at the Z-network of the PV. However, this net shoot-through period is formed by an additional shoot-through period which has drawbacks as it boosts the capacitor voltage to a greater extent beyond the allowable voltage boundary of the capacitor. İn other words, the PV will boost the voltage more than the desired level as per required by reference capacitor voltage of the Z-network. Due to this problem, an improved capacitor voltage control (i-CVC) with general Perturb and Observe (P&amp;amp;O) based on ΔT&lt;sub&gt;0&lt;/sub&gt;&lt;sup&gt;’&lt;/sup&gt; configuration of the changes shoot-through duty cycle to maintain the DC-link of the ZSI is introduced and been tested in simulation case with a resistive load. At the end, this modification able to assist the MPPT output power by increasing the overall system effectiveness of power generation by the PV.&lt;/span&gt;

Modulation control of Impedance inverter for Maximum Output

India has seen a notable increase in adoption of the renewable energy, Various policies and schemes had been proposed in India to focalize on renewable energy sector. For solar energy conversion, an AC module that functions as a grid-connected inverter after a PV module is needed. ZSI is being used to alleviate a myriad of issues that VSI and CSI have. An impedance source inverter provided with triggering pulses generated by maximum boost control modulation technique is presented in this paper. The triggering pulses are generated by bringing the input sinusoidal and triangular waves on the same graph. Maximum boosted output can be achieved through this method just by adjusting its modulation index and shoot-through intervals.

Modern control scheme for Z-Source inverter based PV power generation systems

Z-source inverter (ZSI) based photovoltaic power conversion system (PV-PCS) provides both the DC link voltage boost and DC-AC inversion in single stage with added features. Traditional maximum power point tracking (MPPT) control algorithm generates the required shoot-through interval to output maximum power to the Z-network. At this instant, the voltage across Z-source capacitor is equal to the MPP voltage of PV array. The capacitor voltage cannot be further increased if it is demanded by the load. This paper presents an improved MPPT control algorithm along with modified MPPT algorithm to achieve both the MPPT as well as capacitor voltage control at the same time. Development and implementation of the proposed algorithm has been carried out by Matlab/Simulink software and the results are provided.

Closed‐loop control of the grid‐connected Z‐source inverter using hyper‐plane MIMO sliding mode

In this study, a hyper-plane multi-input–multi-output (MIMO) sliding-mode controller (SMC) is presented for control of the grid-connected Z-source inverter (ZSI). The presented controller can simultaneously control all of the system state variables including grid-side AC current and DC-link capacitors voltage. These state variables are directly regulated by amplitude modulation index and shoot-through interval. The non-minimum phase problem of the capacitors voltage is solved by indirect regulation of the DC-side inductor current. The proposed controller is developed using non-linear MIMO model of the converter; hence, it is possible to apply the proposed controller in a wide operating range. Controller coefficients are designed using Jacobian linearisation approach to ensure stability of the system. According to application of the Lyapunov approach, it is proved that the proposed controller is asymptotically stable against changes of the system state variables. Some simulations are presented to verify the effectiveness and stability of the developed controllers by MATLAB/Simulink toolbox. Also, a laboratory prototype is implemented using a digital signal processor TMS320F28335. Experimental results are given for the presented controller in the single-phase ZSI. It is seen that the experimental and simulation results are in good agreement.

A Pulsewidth Modulation Technique for High-Voltage Gain Operation of Three-Phase Z-Source Inverters

Z-source inverter (ZSI) was recently proposed as a single-stage buck–boost dc–ac power conversion topology. It augments voltage boost capability to the typical voltage buck operation of the conventional voltage source inverter with enhanced reliability. However, its boosting capability could be limited; therefore, it may not suit applications requiring a high-voltage boosting gain. To enhance the boosting capability, this paper proposes a new pulsewidth modulation (PWM) technique to control the generation of the shoot-through intervals in three-phase ZSIs. The proposed modulation technique achieves a reliable high-voltage gain operation without adding any extra hardware to the ZSI structure, which preserves its single-stage buck–boost conversion nature. In this paper, the principle of the proposed modulation technique is analyzed in detail, and the comparison of the ZSI performance under the conventional and the proposed PWM techniques is given. The simulation and experimental results are shown to verify the analysis of the proposed concept.

Trans‐switched boost inverters

Conventional switched boost inverters (SBIs) employ a single LC-pair in the impedance network to boost the input voltage by setting a shoot-through interval in the inverter bridge switches. This study extends the concept of SBIs to the transformer-based switched boost inverters (trans-SBIs). By changing the turn ratio of the transformer, the proposed trans-SBIs can produce a strong voltage gain. Compared with a tapped-inductor Z-source inverter with the same voltage gain at the same transformer turn ratio, the proposed trans-SBIs have only one extra active switch but significantly fewer passive components. Compared with trans-ZSI, the proposed trans-SBIs use a transformer with a lower turn ratio to achieve a higher boost factor. The required current rating of the switches in the proposed trans-SBI is lower than for the alternative ZSIs. The operating principles and the analyses and comparisons with the conventional transformer-based ZSIs are presented. To verify the high boost capability of the proposed inverters, a laboratory prototype was built for both the single-phase and three-phase trans-SBIs.

Switched-Coupled-Inductor Quasi-Z-Source Inverter

Z-source inverters have become a research hotspot because of their single-stage buck–boost inversion ability, and better immunity to EMI noises. However, their boost gains are limited, because of higher component-voltage stresses and poor output power quality, which results from the tradeoff between the shoot-through interval and the modulation index. To overcome these drawbacks, a new high-voltage boost impedance-source inverter called a switched-coupled-inductor quasi-Z-source inverter (SCL-qZSI) is proposed, which integrates a switched-capacitor and a three-winding switched-coupled inductor (SCL) into a conventional qZSI. The proposed SCL-qZSI adds only one capacitor and two diodes to a classical qZSI, and even with a turns ratio of 1, it has a stronger voltage boost-inversion ability than existing high-voltage boost (q)ZSI topologies. Therefore, compared with other (q)ZSIs for the same input and output voltages, the proposed SCL-qZSI utilizes higher modulation index with lower component-voltage stresses, has better spectral performance, and has a lower input inductor current ripple and flux density swing or, alternately, it can reduce the number of turns or size of the input inductor. The size of the coupled inductor and the total number of turns required for three windings are comparable to those of a single inductor in (q)ZSIs. To validate its advantages, analytical, simulation, and experimental results are also presented.

Effective space vector modulation switching sequence for three phase Z source inverters

A new approach in the PWM technique is proposed through proper choice of active vectors and placement of a shoot through (ST) states for three phase Z source inverter (ZSI). Compared to the existing modulation method, the power conversion interval is maximum in this technique which improves the output voltage at higher modulation indices. Also with the inclusion of ST states, the number of switching is less avoiding the switching losses. The switching is performed at higher operating frequency which reduces the voltage stress and the size of LC components. In each sector, the ST interval is properly selected to improve the bus utilisation thus increases the voltage gain of ZSI. Furthermore, the analysis is performed by deriving the expression for the RMS flux ripple over a sub-cycle and evaluated in terms of switching instants which facilitates immediate comparison for all the presented methods. The proposed method is verified through the simulation and experimental results.

Unified MPPT Control Strategy for Z-Source Inverter Based Photovoltaic Power Conversion Systems

Z-source inverters (ZSI) are used to realize both DC voltage boost and DC-AC inversion in single stage with a reduced number of power switching devices. A traditional MPPT control algorithm provides a shoot-through interval which should be inserted in the switching waveforms of the inverter to output the maximum power to the Z-network. At this instant, the voltage across the Z-source capacitor is equal to the output voltage of a PV array at the maximum power point (MPP). The control of the Z-source capacitor voltage beyond the MPP voltage of a PV array is not facilitated in traditional MPPT algorithms. This paper presents a unified MPPT control algorithm to simultaneously achieve MPPT as well as Z-source capacitor voltage control. Development and implementation of the proposed algorithm and a comparison with traditional results are discussed. The effectiveness of the proposed unified MPPT control strategy is implemented in Matlab/Simulink software and verified by experimental results.

A novel capacitor voltage control for Z-source inverter based photovoltaic power conversion systems

AbstractZ-source inverter (ZSI) could be used to realise both DC voltage boost and DC-AC inversion in one single stage with reduced number of power switches for photovoltaic (PV) power conversion systems (PCS). Maximum power point tracking (MPPT) control algorithm provides the shoot-through interval which should be inserted in the switching waveforms of the inverter to output the maximum power to the Z-network. At this instant, the voltage across the Z-source capacitor is equal to the output voltage of PV array. This paper presents a unified MPPT control strategy along with a modified MPPT algorithm to achieve the MPPT as well as capacitor voltage control simultaneously. Development and implementation of the proposed algorithm and comparison with traditional results are discussed. The effectiveness of the unified MPPT algorithm is verified by MATLAB/Simulink software and confirmed by experiment.

A Novel Capacitor Voltage Control for Z-source inverter based Photovoltaic Power Conversion Systems

Z-source inverter (ZSI) could be used to realise both DC voltage boost and DC-AC inversion in one single stage with reduced number of power switches for photovoltaic (PV) power conversion systems (PCS). Maximum power point tracking (MPPT) control algorithm provides the shoot-through interval which should be inserted in the switching waveforms of the inverter to output the maximum power to the Z-network. At this instant, the voltage across the Z-source capacitor is equal to the output voltage of PV array. This paper presents a unified MPPT control strategy along with a modified MPPT algorithm to achieve the MPPT as well as capacitor voltage control simultaneously. Development and implementation of the proposed algorithm and comparison with traditional results are discussed. The effectiveness of the unified MPPT algorithm is verified by MATLAB/Simulink software and confirmed by experiment.