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In this article, a multioutput-based transformerless hybrid solar inverter (TLHSI) with no right half-plane zero (RHPZ) and reduced common-mode leakage/ground current is presented for photovoltaic (PV) based microgrid applications. In the proposed multioutput TLHSI, two magnetically coupled inductor coils are placed between the input and dc output sides along with a dc-link capacitor to continuously provide the stored energy to the dc load so that the RHPZ is eliminated and, thus, makes it a minimum phase system. Furthermore, a hybrid unipolar sinusoidal pulsewidth modulation technique is established to nullify the high-frequency components of common-mode voltage across the PV to ground stray capacitor. Also, it normalizes both dc and ac loads at the same instant from a single dc input during each operating state of the proposed TLHSI. The shoot-through issue is resolved in the proposed TLHSI, which increases the system reliability. Furthermore, as the deadtime is not required in between the switching pulses, the quality of the inverter output voltage improves. The performance analysis of the proposed TLHSI is compared with the existing topologies. To validate the performance of TLHSI, a scaled down 340 W laboratory prototype is developed. [ABSTRACT FROM AUTHOR]

A 17‐level hybrid multilevel inverter (HMLI) using modified grey wolf optimisation (MGWO) is proposed here. The proposed HMLI requires only a single dc source and a lesser number of circuit elements to obtain a multilevel voltage level. The proposed HMLI can also enhance the input voltage and has reverse current carrying capability. The selective harmonic elimination pulse width modulation technique is implemented through MGWO for determining the optimal switching angles of the proposed HMLI to eliminate lower order harmonics. The MGWO algorithm gives improved results as compared to other existing optimisation algorithms in terms of fitness value, convergence speed and harmonic profile of the output voltage. The proposed HMLI is also compared with some of the other existing HMLIs in terms of the number of circuit elements, peak inverse voltage and total blocking voltage to exhibit its advantages. Finally, a 550 W prototype is fabricated in the laboratory to evaluate the effectiveness of the proposed HMLI. [ABSTRACT FROM AUTHOR]

The change in environmental conditions and dynamic loading distort the smooth and stable MPPT operation. Conventionally, boost and boost-derived converters are used for MPPT operations, which inherently display right half plane zero (RHPZ). The presence of RHPZ causes a transient undershoot and overshoot in the output voltages. A tradeoff between bandwidth and stability is another issue with such converters. In order to address these issues, a minimum-phase bipolar converter (MPBC) is proposed to facilitate the MPPT operation. The MPBC is derived by combining the Ćuk and SEPIC converters with some circuit modifications in both of them. These circuit modifications eliminate RHPZ from the proposed MPBC. Due to the minimum-phase behavior, the proposed MPBC can achieve high bandwidth with improved phase margin, which is required for the fast and stable MPPT operation. MPBC can operate at the high load current and provides wide operating ranges for the MPPT operation due to its buck and boost capabilities. The transient analysis of the proposed MPBC is carried out to compare its performance with the conventional bipolar converter. A 600-W scaled-down laboratory prototype is developed and implemented using Texas Instrument TMS320F28335 processor to validate the performance of the MPBC for photovoltaic systems. [ABSTRACT FROM AUTHOR]

A minimum-phase dual output hybrid converter for standalone hybrid ac/dc supply systems is proposed in this article. Due to its circuit arrangement, the converter eliminates the right half-plane zero from the control-to-dc output voltage transfer function (i.e., making the system minimum-phase) and gives simultaneous ac and dc outputs using single-stage power conversion. Due to the minimum-phase behavior, the converter is capable of operating at a high load current while maintaining closed-loop stability. Further, it enables simpler controller design and faster dynamic response. As it has two inductors, one at the main input voltage terminals and another at the output dc voltage terminals, it gives continuous input/output currents. Also, it gives step-down/step-up dc output voltages along with the step-down ac output voltage based on the duty ratio. It also has inherent shoot-through protection capability, which results in reliable power conversion on the occurrence of misgating of the switches caused by electromagnetic interference. A hybrid pulsewidth modulation scheme is developed to achieve simultaneous ac and dc outputs. Detailed mathematical modeling is carried out to demonstrate the properties of the converter, and its experimental validation is done through a laboratory prototype. Moreover, at different loading conditions, efficiencies of the converter are measured for varying dc load (having constant ac load) and varying ac load (having constant dc load), to show its effectiveness. [ABSTRACT FROM AUTHOR]

The conventional converter needs to be operated at a high duty cycle to achieve maximum possible voltage gain. This leads to severe reverse recovery of switches, increases losses, and reduces efficiency. This study presents a modified switched-capacitor-based high gain continuous input current quasi-Z-source converter (qZSC) for DC microgrid applications. The proposed converter utilises the embedded switched-capacitor techniques and can give a high voltage gain with a low duty ratio compared to the conventional converters. The proposed converter also experiences less capacitor voltage and inductor current stresses compared to the conventional Z-source converters. This facilitates the use of lower-rated capacitors and inductors for higher power applications. Detailed steady-state, small-signal, and power loss analysis of proposed qZSC is discussed in this study. A prototype of 100 W is designed and implemented using TI TMS320F28335 Experimenter Kit to verify the operation of the proposed converter. [ABSTRACT FROM AUTHOR]

This study presents a hybrid multilevel inverter (HMLI), capable of generating 19 voltage levels using a single DC voltage source. The peak inverse voltage of all the switches is restrained within the input DC source voltage in the proposed HMLI, which requires only three capacitors and 15 switches to achieve 19 voltage levels. In the proposed HMLI, one of the capacitors is self‐balanced, while the other two capacitors are balanced using a modified finite control set model predictive control (MFCS‐MPC). The proposed MFCS‐MPC reduces the computation time considerably without affecting the performance of the system. The proposed HMLI is compared with some other HMLI topologies to show its merits in terms of active and passive components. Finally, the steady‐state and dynamic performance of the proposed topology and its control algorithm is validated through simulation and experimentation for a 1 kW prototype. [ABSTRACT FROM AUTHOR]

This article proposes a modified grey wolf optimization (MGWO) which has improved rate of convergence and avoids local optima stagnation. This is achieved by improving the exploration–exploitation balance in conventional grey wolf optimization (GWO). Moreover, the use of weighted-distance strategy allows quick identification of the global optima in the proposed MGWO. This optimization is then applied for the control of a three-phase, 11-level hybrid cascaded multilevel inverter (HC-MLI). Selective harmonic elimination pulsewidth modulation technique is implemented through MGWO which generates optimal switching angles for the HC-MLI so as to eliminate lower order harmonics such as 5th, 7th, 11th, and 13th from the output voltage. In MGWO optimized HC-MLI, balancing of capacitor voltage is made possible at higher modulation index by making use of the available redundant switching states. The performance of the proposed work is validated through simulation and experimentation on a 1.5 kW prototype. The results obtained through simulation show that the MGWO algorithm is more efficient and accurate than other reported algorithms such as GWO, genetic algorithm, and particle swarm optimization in terms of performance, harmonic reduction, and convergence rate. [ABSTRACT FROM AUTHOR]

A magnetically coupled boost (MCB) converter with the enhanced equivalent series resistance (ESR) of the filter capacitor for DC microgrid applications has been presented in this study. The proposed MCB converter with enhanced ESR filter capacitor uses only four state variables and exhibits a fourth-order minimum phase behaviour because of the complete elimination of right half plane zero. The characteristic of displaying fourth-order minimum phase behaviour of the proposed MCB converter with the enhanced ESR filter capacitor makes the design and analysis simple. Closedloop operation of the proposed MCB converter with the enhanced ESR filter capacitor with photovoltaic input using maximum power point tracking has been carried out to verify its applicability in DC microgrid. Steady state and dynamic modelling of the MCB converter has been carried out to demonstrate its advantages. The proposed algorithm is validated on a 145 W prototype through simulation and experimentation. [ABSTRACT FROM AUTHOR]