Peak Inverse Voltage Research Articles

Extendable Multiport High Step-Up DC–DC Converter for Photovoltaic-Battery Systems With Reduced Voltage Stress on Switches/Diodes

In the standalone photovoltaic (PV)-battery power system, a multiport converter is more desirable than several single-input converters as it has advantages of the simpler circuit, higher efficiency, and lower cost. In this paper, a novel structure based on a non-isolated high step-up multi-port converter (MPC) is proposed. The proposed MPC has the capability of providing high voltage gain and low normalized peak inverse voltage (NPIV) across semiconductor devices. Maximum power point tracking (MPPT) algorithm can be applied for each PV input source, which is an effective method to prevent mismatches among PV modules. Different from the existing extendable MPCs, the proposed MPC can extend both unidirectional input ports and bidirectional ports to involve more types of renewable energy sources and energy storage devices. Continuous input currents and modularity are the other profits of the proposed MPC. Various operating modes, steady-state analysis, and design considerations have been discussed. Comparison results verify the above advantage of the proposed MPC. Finally, a 240W laboratory prototype is designed to validate the performance of the proposed MPC.

Self-balanced high gain switched-capacitor boosting inverter with lower cost function

ABSTRACT This paper discusses in detail a new 17-level inverter that employs a switched-capacitor (SC)-based configuration. The proposed SC-based inverters require just a single DC power supply, three capacitors, four diodes and 13 switches. The peak inverse voltage of the proposed 17-level SC-based inverter half-bridge is cut in half when compared to the prior arrangement, which was published not long ago. The blocking voltage is reduced by an order of magnitude as well. Many of the features of the proposed SC-based inverter, such as a high boosting gain factor (G) of eight times, self-balanced capacitor voltage and decreased voltage ripples in capacitors, have been carried over to other SC-based MLIs. The circuit description, working theory, PWM modulation techniques and capacitor voltage ripples are all examined. Finally, the results of the experiments show without a doubt that the proposed SC-based inverter can be made.

A double boost 9‐level switched capacitor‐based multilevel inverter for photovoltaic applications

SummaryA self‐balancing 9‐level inverter is proposed in this paper. To generate a 9‐level voltage with a gain of two requires a single DC source, eight power switches, three capacitors, and two diodes. Without additional circuitry, the voltages of the capacitors in the proposed topology can achieve inherent balance. The peak‐inverse‐voltage (PIV) of six power switches equals or less than the source voltage, and the other two are twice. As power switches are complementary, the proposed topology requires fewer gate drivers. Furthermore, the self‐balancing capability of capacitors' voltage helps in simple control complexity. The description of topology, mode of operation, modulation strategy, and design of the capacitor of proposed topology are presented. The advantages of the proposed inverter are examined by comparing it with switched capacitor multilevel inverters (MLIs). Finally, a 9‐level prototype is built to verify the theoretical analysis and the practical efficacy of the proposed inverter.

A novel multilevel inverter with reduced components and minimized voltage unbalance

Multilevel inverters are an emerging area of research in the field of power electronic circuits and applications. It has many advantages like near-sinusoidal output voltage, lower total harmonic distortion (THD), reduced dv/dt stress, lower peak inverse voltage (PIV) and so on. But there are some associated problems as well such as cost, size complexity, and capacitor unbalance voltage. Here a novel nine level inverter topology has been proposed which addresses the issue of high no of switching and capacitor voltage unbalance. The proposed system has numerous advantages. The cost, size and complexity are reduced and the voltage unbalance problem is solved. The voltage stress across the switches is also reduced. The power loss distribution among the switches is optimum. So, the efficiency of the system is improved. Hence the overall system performance is improved. The system performs well for varying load like resistive, inductive as well as motor load. The stator voltage speed control of a single-phase induction motor has also successfully been achieved. The pulse width modulation PWM technique has been used for producing the switching pulses. The complete simulation analysis of these systems has been realized using MATLAB software. A comparative analysis of this system with the recently proposed systems has been done which shows significant advantages in all the above mention areas.

A Switched Capacitor-Based 13-Level Inverter With Reduced Switch Count

In this article, a 13-level switched capacitor multilevel inverters (SC-MLI) based single-phase inverter is proposed in which desired levels of output ac voltage are realized with reduced number of switch counts. The proposed inverter requires 12 switches, three diodes, one input dc source, and three capacitors. The requirement of less number of switches reduces the requirement of gate drivers, which enhances power density of converter. The second challenge in SC-MLI is to maintain self-voltage balancing across the capacitors. The self-voltage balancing capability becomes poor at low values of modulation index. The capacitors connected in proposed SC-MLI are capable to maintain the self-voltage balancing without requiring auxiliary circuits or complex control strategies. The operation of capacitors is self-balanced at all regions of modulation index values. The comparison of the proposed SC-MLI is carried out with state-of-art SC-MLIs discussed in the literature using the parameters like peak inverse voltage and total standing voltage. The switches connected in the proposed 13-level SC-MLI undergoes less voltage stress as compared to the SC-MLI configurations discussed in the literature. The proposed SC-MLI is highly competent to achieve good power quality and is capable to ensure voltage balancing of capacitors even at low values of modulation index. The validation of the proposed inverter topology is carried out using a laboratory prototype. The efficiency of the converter claimed using the simulation results is observed to be 96.2% while the efficiency evaluated using the experimental results is 94.1% at 500 W.

Switched Capacitor Based High Step-Up Multilevel Inverter with Self-Balancing Ability and Low Switching Stress

In this article, the switched capacitor (SC) based high step-up multilevel inverter is proposed with self-balancing capability. The proposed SC inverter topology is to step up the high output voltage from the very low input voltage without any bulky transformer. This proposed inverter generates single-phase AC voltage with a frequency of 50 Hz from a very low DC input voltage of 50 V with any intermediate DC-DC conversion stage. Hence, the proposed SC inverter is highly suitable for fuel cell, photovoltaic (PV) applications, and shunt active power filter (SAPF). To control the SC inverter, a multicarrier pulse width modulation (PWM) technique is engaged in the inverter. The high step-up voltage level can be achieved by the charging and discharging process of the SC. Furthermore, the stress voltage of the switches does not exceed the applied voltage and the total standing voltage of the inverter is greatly reduced without H-bridges. The comparative analysis of the proposed SC inverter is made for the components, peak inverse voltage (PIV), total standing voltage (TSV), boosting ability, and voltage balancing of capacitors. The main theme of the paper is producing a thirteen-level sinusoidal current with acceptable total harmonic distortion (THD) at different loads, low PIV, TSV, high boosting ability, and self-balancing of capacitors with fewer passive components. The whole system is examined by using MATLAB/Simulink.

A Nine-Level Switched-Capacitor Step-Up Inverter with Low Voltage Stress

This paper proposes a nine-level switched-capacitor step-up inverter (9LSUI) which can achieve a quadruple voltage gain with single dc source. Differing from other switched-capacitor inverters, the voltage stress of switches is effectively reduced due to the elimination of H-bridge, and the peak inverse voltage of all switches is kept within 2Vdc. In addition, the proposed inverter is able to integrate inductive load, and the capacitor voltage self-balancing can be achieved without any auxiliary circuits. Moreover, the topology structure can be flexibly extended to raise the output levels, and the peak inverse voltage of switches can remain constant with the increase of sub-modules in the extended structure. Comprehensive comparisons are performed to verify the outstanding advantages of the proposed inverter. Finally, the steady-state and dynamic performance of the proposed inverter is validated through an experimental prototype, and the experimental results are provided to prove the theoretical analysis.

A single-input extended multilevel inverter based on switched-capacitor with reduced number of devices

The existing multilevel inverter (MLI) has problems such as a large number of devices, a complex structure, and a large voltage stress of the semiconductor. These shortcomings are not conducive to the modularization, high efficiency and miniaturization of the inverter. Therefore, a topology of extended switched capacitor multilevel inverter utilizing single power supply is proposed. In which, the capacitor is used as a virtual power supply, through the switching control strategy, capacitors and the power supply are reasonably combined, then a multilevel output voltage can be acquired. The proposed topology mainly has the following advantages. Firstly, it can be expanded to further increase the number of output levels. Secondly, the structure of the basic switched capacitor circuit used in the topology is simple, which can reduce the number of devices when the output is the same. Thirdly, the terminal H-bridge for output voltage polarity conversion can be eliminated in the proposed topology, which is beneficial to reduce the total standing voltage and peak inverse voltage. Therefore, an opportunity for the application of the inverter in medium and high voltage is provided. Additionally, the inherent capacitor voltage self-balancing capability of the proposed topology can eliminate the additional balancing control algorithms, therefore, the modulation strategy is simplified. Finally, the correctness and effectiveness of the topology are verified by the extensive simulation and experimental results carried out on the 13-level inverter.

A Switched-Capacitors-Based 13-Level Inverter

The merit of switched-capacitors-based multilevel inverters (SCMLIs) is generally quantified in terms of a “cost function” (CF) that incorporates parameters such as voltage gain, component count, total standing voltage (TSV), and number of levels. In this article, a 13-level inverter is proposed with the aim of achieving a low value of CF. The proposed single-stage SCMLI uses one input source and three capacitors to attain a voltage gain of 3. It requires 13 power switches, of which the peak inverse voltage (PIV) of nine switches is restricted to the source voltage. The remaining four switches have PIV equal to twice the source voltage and they operate at low frequency. Thus, for all switches, the PIV is less than the amplitude of the output voltage. Moreover, the capacitors are self-balanced at all regions of modulation index values. The proposed inverter is validated through simulation and experimental results. A comparison of the proposed topology with other contemporary SCMLIs shows that it is highly competent in terms of CF, PIV and TSV requirements, waveform resolution, and capability to achieve voltage balancing of capacitors at low values of modulation index.

A new design self‐balanced 13‐level switched‐capacitor inverter

AbstractThis study introduces a novel switched‐capacitor (SC) inverter with a simple architecture. The proposed topology synthesized a 13‐level voltage waveform with a boosting factor of six. The unique features of the proposed topology are the self‐balancing property of capacitors voltage, high boosting factor, least cost function, lower peak inverse voltage, and lower per‐unit total standing voltage. A brief analysis of the circuit description, operating principle, the modulation scheme has been presented. The proposed topology's advantages over the existing topologies have been demonstrated through comparative investigations. Finally, the simulation and experimental findings have confirmed the feasibility and dynamic performance of the suggested topology.

A Novel Fundamental Frequency Switching Operation for Conventional VSI to Enable Single-Stage High-Gain Boost Inversion with ANN Tuned QWS Controller

Single-stage high-gain inverters have recently gained much research focus as interfaces for inherent low voltage DC sources such as fuel cells, storage batteries, and solar panels. Many impedance-assisted inverters with different input stage configurations have been presented. To decrease passive component sizes, these inverters operate at high-frequency switching. The high-frequency switching optimizes the passive component sizes but introduces many challenges in the form of high-frequency inductor design, control complexity, high-frequency gate driver requirements, high semiconductor losses, and electromagnetic interferences. This article proposes a novel fundamental frequency switching operation for the conventional voltage source inverters (VSI) to operate as a single-stage high-gain inverter. As the novel operational strategy changes the behavior of conventional VSI from buck inverter to a boost inverter, it is hereafter termed as a novel inverter. By virtue of the operation strategy, switches withstand peak inverse voltage (PIV) equal to DC link voltage, unlike other impedance assisted boost inverters where PIV across switches is the amplified DC voltage. The proposed inverter can invert low-level DC voltage to high voltage AC with low total harmonic distortion (THD) in a single stage without the help of any external filter. A novel quarter-wave symmetric phase-shift controller is proposed for variable voltage and frequency control of proposed inverters tuned by a back-propagation thin-plate-spline neural network (BPTPSNN). Mathematical analysis with experimental validation is presented. Experimentation is carried out on a prototype of 2 kW for single-phase resistive load, induction motor, and non-linear loads.

Modified grey wolf optimisation based reduced device count 17‐level hybrid multilevel inverter

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.

Single DC source diode‐assisted hybrid multilevel inverter using a reduced number of active and passive components

In this study, a seventeen-level diode-assisted hybrid multilevel inverter (DAH-MLI) is proposed. The DAH-MLI eliminates any external voltage balancing and/or sensing circuit by inherently balancing the capacitors using a series–parallel combination of capacitors and DC voltage source. The DAH-MLI uses only one DC source and a reduced number of active and passive elements to generate a multilevel staircase output voltage. The proposed circuit can also be extended to obtain the higher number of voltage levels than seventeen by the addition of a single module comprising of two diodes, one switch, and one capacitor. The proposed DAH-MLI can boost the input voltage and possesses reverse current carrying capability. The proposed DAH-MLI is compared with several existing topologies on the basis of the number of active and passive components, total standing voltage, and peak inverse voltage to verify its advantages. A cost function is used in this study to compare the proposed DAH-MLI and other existing typologies. Finally, the performance of the proposed DAH-MLI is validated through a 570 W experimental prototype.

A New Grid Interactive 11-Level Hybrid Inverter Topology for Medium-Voltage Application

Multilevel inverter (MLI) has wide applications due to its numerous advantages. An improved configuration of eleven-level MLI suitable for medium-voltage range has been proposed in this article. The proposed topology contains two half-bridge submodules, one flying capacitor MLI, and one full bridge submodule. A simple method of capacitor voltage balancing has been demonstrated with less ripple. The study about the effectiveness of proposed MLI has been justified by loss calculation to find the efficiency and voltage ripple analysis of the capacitor. The comparative assessment in terms of switch count, driver count, capacitor requirement, device peak inverse voltage, total standing voltage (TSVp.u), cost function, etc. for the developed hybrid inverter (HI) topology has been presented to establish the utility of the proposed HI. This topology has been checked for its operation under various operating conditions, including frequency and modulation index variation, overmodulation range, and also with motor load. The grid connectivity option of the proposed HI has been verified to ensure the suitability for application with renewable energy sources.

Reduced voltage stress hybrid multilevel inverter using optimised predictive control

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.

A Flying Capacitor-Based Multilevel Inverter Architecture With Symmetrical and Asymmetrical Configurations

In this article, a novel flying capacitor-based multilevel topology is presented to minimize the size and cost. The proposed topology can operate in the symmetrical and asymmetrical configuration of dc sources and produces the 9-level and 25-level output voltage, respectively. The minimized device count, negative polarity voltage generation without auxiliary H-bridge, reduced maximum peak inverse voltage across the switches, and inherent voltage balancing across the floating capacitors are the main advantages of the proposed topology. Two extended topologies are proposed, and various necessary parameters are derived from achieving a higher number of output voltage levels. The effective comparison is furnished in terms of switches, diodes, capacitors, total standing voltage, and cost function to show minimization of device count of the proposed topology against the recent popular topologies. The extensive simulations in MATLAB <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\backslash $ </tex-math></inline-formula> Simulink are carried out to study the operation of proposed topology and feasibility is validated through the laboratory experimental tests. The performance of the topology under dynamical variation of frequencies, modulation indexes, and load are studied and respective results are presented.

Nine‐level voltage‐doubler bi‐polar module for multilevel DC to AC power conversion

A major disadvantage of two-stage topologies of switched capacitors based multilevel inverters is the use of H-bridge switches which endure high peak-inverse-voltage (PIV). In such topologies, the H-bridge stage is preceded by a level-generation stage which synthesises unipolar voltage levels. In this work, a bi-polar module is proposed which can synthesise nine levels at the AC terminals with a single DC input. The proposed module uses power switches with PIV equal to that of the input DC source. Use of switched capacitors in each of the proposed module enables a voltage gain of two. Such bi-polar voltage-doubler modules can be easily connected in a cascaded fashion to increase the number of levels, without involving H-bridge switches. Working modes of the module ensure that the capacitors are self-balanced. A complete analysis of the proposed module is presented. Also, experimental results are presented for validation. In addition, a comparison with other topologies has been presented.

A novel 49-level asymmetrical modular multilevel inverter: analysis, comparison and validation

High progresses in the field of power electronic create an appropriate bed to introduce new and upgraded multilevel inverter topologies. Such these topologies contain remarkable inherent advantages like: high quality staircase sinusoidal output voltage, low number of switches, low peak inverse voltage, et cetera. In this paper, a novel modular asymmetrical multilevel inverter is proposed to reduce the number of inverter’s components, and accordingly make a cost-effective structure with excellent voltage-step creation. In accordance with the configuration of utilized switches and magnetite of DC voltage source, the proposed structure can provide a high-step staircase sinusoidal voltage without high increase of semiconductors. Consider this; symmetrical condition of the proposed structure also takes low number of switches as compared to other symmetrical structures. Finally, both the MATLAB/SIMULINK and experimental results have confirmed the accurate operation and voltage-step creation capability of the suggested multilevel inverter.

A Self-Balancing Five-Level Boosting Inverter With Reduced Components

Two-Stage boosting multilevel inverters (MLIs), which are highly suitable for photovoltaic power plants, are known to suffer because of the high voltage stress on the switches of second stage. One of the ways to confront this issue is through eliminating the front-end booster. However, this leads to increased structural and control complexity of the resulting integrated boosting MLI. This letter presents a single-stage boosting MLI requiring lesser number of switches, diodes, and capacitors for renewable power generation applications. It requires nine switches and only one capacitor for five-level voltage generation. The topology has inherent self-balancing capability, thereby does not need additional balancing circuitry. The proposed topology has a uniform peak inverse voltage stress on the switches of value equal to the input dc voltage. A less complicated logic-form-equations-based gating pulse generation scheme is designed for enabling the proposed MLI to maintain its capacitor voltage. Further, a comparative study with state-of-the-art topologies is carried out to demonstrate the superior performance of the proposed topology. Finally, the feasibility of the proposed topology is validated through experimental tests and the corresponding results are elucidated.

Switched capacitors 9‐level module (SC9LM) with reduced device count for multilevel DC to AC power conversion

Switched capacitors (SCs)-based modules are being increasingly used for multilevel DC to AC power conversion, especially for low input voltage applications. Many of these topologies operate in two stages involving H-bridge switches, which endure high-voltage stress. The SC 9-level module (SC9LM) presented here operates in a single stage with one DC source and two capacitors. In addition, the peak inverse voltage of all power switches is confined to the voltage of the input DC source. The proposed 9-level module ensures a reduced number of power switches. In addition, with appropriate utilisation of states, two of the eleven switches in the module operate at fundamental switching frequency, thereby minimising the switching losses. A single SC9LM achieves a voltage gain of two. The proposed module is validated through circuit analysis followed by simulation and experimental results.