Level Inverter Research Articles

An Application of Neural Network-based Sliding Mode Control for Multilevel Inverters

Multi-level 3-phase inverters using cascaded H-bridges are becoming prominent in the electric drive and renewable energy sectors due to their high capacity and ability to withstand high voltage shocks. Therefore, the modulation and control techniques used in these multilevel inverters have a crucial influence on the quality of the output voltage they produce. The significantly high common-mode voltage amplitude they generate is one of their disadvantages, causing leakage currents and harmonics. This article proposes a new technique using sliding mode control combined with neural networks to manage a three-phase multi-level inverter. The research objective of this innovative technique is to eliminate the need for current controllers and conventional modulation that relies on carrier signals, reducing hardware calculations and enhancing dynamic response. In addition, it demonstrates the ability to minimize harmonics, common mode voltage, and the number of switching counts, thereby limiting the inverter switching losses and increasing device performance. Simulation results performed on a 5-level 3-phase inverter using cascaded H-bridges have confirmed the effectiveness of the proposed method.

A Reduced Switch Count Five Level Inverter With Extended Linear Modulation Range Up to Full Base Speed

A Reduced Switch Count Five Level Inverter With Extended Linear Modulation Range Up to Full Base Speed

Design and development of photovoltaic solar system based single phase seven level inverter

For solar photovoltaic (PV) systems, an upgraded triple gain seven-level inverter that works both independently and while connected to the grid is proposed. The two-stage configuration of the system is boost cascaded. The first stage has a one switch improved gain converter (OSIGC) to increase and normalize the input direct current (DC) voltage, and the second stage includes a unique seven level alternating current (AC) is produced via a multilevel inverter (MLI) design with triple voltage gain. The proposed OSIGC is appropriate for a broad range of conversions. The voltage gain in MLI was achieved using switched capacitor techniques. The DC-DC converter can achieve a maximum voltage gain of twelve and the MLI can achieve a maximum voltage gain of three, resulting in a DC-DC-AC voltage that can reach 36. Maximum power point tracking (MPPT) technique based on modified perturb and observe (PO) is used in OSIGC to maximise PV module power utilisation, and MLI control utilises sinusoidal pulse width modulation (SPWM) realistically. For the purpose of analysing the suggested system, a 200 Watt prototype statel is created. With a total harmonic distortion (THD) of 0.181%, up to 92.12% of the converter system’s overall efficiency is possible.

Design and control of LSTM-ANN controllers for an efficient energy management system in a smart grid based on hybrid renewable energy sources

Many isolated locations, including hilly areas, remote sites, and military camps, lack feasible access to the main power grid. In these conditions, locally established Microgrids can provide the necessary power supply. However, to meet the demands of these isolated areas, numerous individual Microgrids are required. Although some of these Microgrids might be integratable, geographical constraints may preclude full integration. Under these circumstances, the establishment of a smart grid—integrating multiple Microgrids with a battery management system—can potentially solve many power supply issues. A smart grid control system paired with a centralized battery management system is proposed in this paper. The system considers the use of multiple renewable energy sources at various locations for stable and reliable power generation. The proposed method incorporates a long short-term memory (LSTM)-based artificial neural network (ANN) to ensure a stable, high-quality power supply at different load buses. Additionally, this work introduces an artificial intelligence-based operating system designed to maintain energy management under various conditions. To enhance voltage quality, a 7-level aligned multilevel inverter is incorporated into the system. As compared with PI and Fuzzy controllers, the proposed method with LSTM-ANN controller is improved the power quality under sudden changes in the system which are also presented in results, Voltage variation of PI, Fuzzy, and LSTM-ANN is 370V,180V,and 70V . The effectiveness of the proposed energy management system (EMS) is verified by using a hardware-in the-loop approach with OPAL-RT modules, yielding realistic results.

A novel 7-level reduced-switch MLI topology fed PMSM drive for electric vehicle system

The compact and efficient design motivates the renewable energy-powered permanent magnet synchronous motor drive for electric vehicle applications. The available renewable energy is interfaced with a power drive by employing an electronic commutator such as a conventional 3-level inverter. But, the multilevel inverter produces favorable merits by producing staircase output voltage from several input direct current (DC) sources. The cascaded H-bridge multilevel inverter plays a significant role in many applications, but it was developed only for limited voltage levels. The major problem in cascaded h-bridge multilevel inverter (CHBMLI) requires more switching devices for higher voltage levels, which increases the size, cost and space of the electric vehicle (EV). To overcome above-mentioned problems, a new objective has been developed by employing the novel Reduced-switch multilevel inverter topology for higher voltage levels. This improves the voltage quality and reducing the harmonic level, and common-mode voltage issues. The main contribution of this work is, developing the novel 5-level, 7-level reduced-switch multilevel inverter (RSMLI) topologies with reduced switching devices with favourable merits over CHBMLI topology. Finally, the performance of proposed novel 5-level and 7-level RSMLI topologies fed PMSM drive for EV system has been verified, by using MATLAB/Simulink computing tool, and simulation results are presented with comparisons.

Voltage and Current Control Strategy for Grid Connected WECS Employing Two and Three Level Voltage Source Converters

This paper presents voltage and current control strategy for grid connected variable speed wind turbine induction generator employing two and three level voltage source inverters. Induction generators are widely used because of its low cost, robust construction and capability of feeding active power to load without getting reactive power from separate source. The mechanical energy required to drive the generator is obtained from a variable speed wind turbine. Three phase induction machine is excited from a three phase voltage source converter. The DC voltage of the capacitor is inverted and fed to the three phase grid using a current controlled voltage source inverter. Control strategy has been developed for maintaining the DC link voltage constant and also to feed the power at unity power factor to the grid, even though there is variation in wind speed. It is also shown that the harmonics are considerably reduced when a two level inverter is replaced by a three level inverter. The simulation study has been carried out using MATLAB/Simulink. Simulation results indicate the feasibility of control strategy.

Development of a new mixed 5-level inverter for 3 kW household photovoltaic applications

Multilevel inverters are well used in high power electronic applications (about 10 kW) because of their ability to generate a very good quality of waveforms, reducing switching frequency, and their low voltage stress across the power devices. However, inverter architecture must be modified in order to take into account the different photovoltaic (PV) problems in conventional installation. This paper presents a comparative study of 5-level Neutral Point Clamped (NPC) and a new mixed 5-level inverter. The theoretical study is validated using simulation with the LTspice environment. The output voltage and total harmonic distortion are particularly compared. An experimental 5-level inverter was realized in order to validate analytical results.

A three phase 3-level inverter with reduced THD factor

The paper presents an mathematical analysis of a stepped function denoted as fN=6 . This function describes precisely an output voltage waveform of a 3-level inverter. The analysis proves that cascaded inverters give a very good performance of the output voltage according to a criterion of minimal THD. Optimal parameters are indicated in the paper. They permit to diminish the THD factor to a level below 21% while in standard NPC inverters such a result requires special treatment.

State and Space Vectors - Complementary Description of the 2-level VSI

The paper deals with a generalized description system of the two level inverter. Two methods of mathematical approach to the representation of the converter’s state are presented and discussed. One method is standard space vector and the other, originally designed by authors, is state vector representation. The notational system provides a general simplification and standardization of vectors identification. It contains a novel handy proposal of notation and marking which is useful for converter description. The notation system permits to accomplish a comparison and correlation between space and state vectors. It describes state and space vectors by use of the same numbers. Thanks to these properties the proponed mathematical tool can be extremely useful in designing the control algorithms for easy implementation and fast performance of the converter

Efficiency improvement with intelligent control of induction motor drives

The energy saving potential of induction motor drives is investigated. Two new aspects are identified, a multilevel frequency inverter and the speed control with variable rotor flux. Multilevel inverters with new wide-bandgap semiconductors for low voltage electrical drives (<1000 V) reduce power semiconductor losses, voltage transients at the motor windings and harmonic losses in the cables. The power semiconductor losses of a two-level and a three-level inverter are compared. At 20 kHz switching frequency the losses of the three level inverter are 38 % lower compared to the two-level inverter. Another efficiency improvement potential is the speed control with variable rotor flux instead of commonly used constant flux. The rotor flux for maximum efficiency depends on the actual load and speed of the motor. The optimal rotor flux for maximum motor efficiency can be pre-calculated for each load and speed and implemented as reference value for rotor flux control in the frequency inverter. The maximum efficiency improvement with an 11 kW induction motor at small load reaches 35 % in motor and 45 % in generator operation mode. An increase in efficiency can be reached below 2/3 of rated torque in the whole speed range from 10 to 100 Hz.

A dual source fed eleven level switched capacitor multilevel inverter with voltage boosting capability

This work introduces an 11-level switched-capacitor multilevel inverter (SCMLI) designed for solar photo-voltaic (PV) applications, capitalizing on the growing popularity of multilevel inverters due to their superior power quality. With a 1.67-times boosting capability, the proposed SCMLI employs 10 switches, 2 DC supplies, and 2 capacitors to achieve an 11-level output voltage waveform. The topology requires only seven driver circuits, incorporating 2 bidirectional switches and 3 complementary pairs of switches. The proposed inverter has intrinsic capacitor self-balancing features since the capacitors are connected across the DC voltage source at different times throughout a basic cycle to charge the capacitors at a level of input voltage. A thorough comparison between the topology and recently developed SCMLI’s has been presented. The comparison demonstrates the effectiveness in terms of switches, capacitors, sources, efficiency, total standing voltage (TSV), and boosting capacity. To experimentally validate its performance, the suggested SCMLI undergoes testing using a frequency-based switching method. The topology exhibits low total harmonic distortion (THD) of 7.65% in its output voltage waveform and 0.89% in the output current waveform.

Single-Phase nine-level inverter for photovoltaic application

Electrical power play a very important rule in 21th century, but non-conventional sources scale down day by day. Not only that concern for the environmental pollution around the world, so now a day’s photovoltaic (PV) power systems are getting more and more widespread with the increase in the energy demand. This paper proposed a Single-Phase nine level inverter with voltage control method using semi conductor power devices for photovoltaic systems. The proposed inverter system gives better voltage regulation, smooth results and efficiency compared to multi-level inverters. The inverter is capable of producing nine levels of output voltage levels (Vpv, 3Vpv/4,Vpv/2, Vpv/4, 0, -Vpv/4, -Vpv/2, -3Vpv/4, -Vpv). The proposed inverter was verified by using simulation of Matlab / Simulink software.

Variable Speed Wind Energy System Based on a Synchronous Generator with a Three Level Inverter.

The aim of this paper is to show the application of a three level inverter as a grid interface for a variable speed wind energy conversion system. New megawatt wind turbines demand for the connection at higher voltage levels. Multilevel level inverters provide the solution for connecting these wind turbines at voltages over 1 kV. A variable speed wind energy conversion system based on a synchronous generator with a three level inverter has been completely modelled. Then, the dynamic performance of this wind energy conversion system has been studied by simulation. The simulation results show the appropriate behaviour of this system.

A Comprehensive Survey on Harmonic Elimination in Multilevel Inverters Using Optimization Techniques for Power Quality Improvement

Background: Renewable energy sources offer sustainable solutions, but the conversion of DC energy into AC energy, commonly used in electrical devices necessitates inverters. Multilevel inverters have gained favor over conventional two-level inverters in high-power, mediumvoltage industrial and renewable energy applications due to their high switching frequency capabilities and ability to produce low-harmonic distortion voltage, ensuring superior power quality. Aims: This study focuses on addressing the adverse effects of harmonics in electrical systems and investigates methods to eliminate them in multilevel inverters. Methods: This study summarized current research works on traditional and advanced harmonic removal optimization strategies in multilevel inverters to highlight the limitations, objectives, THD%, and summary of existing works. Moreover, this study applies selective harmonic elimination techniques in 7-level and 15-level inverters using PSO and IPSO optimization algorithms to minimize THD and enhance inverter performance. Results: The study summarizes current research on harmonic removal strategies in multilevel inverters, revealing the prevalent use of MATLAB/Simulink in research endeavors. Various modulation and optimization techniques have been explored to achieve low THD in the output waveform, aligning with IEEE 519 standards for power system harmonic distortion. Furthermore, the comparative analysis part highlights increasing THD improvement with higher inverter levels. The 15-level inverter stands out, achieving 6.75% THD with PSO and 4.12% with improved PSO, meeting IEEE 519's THD limit. Conclusion: The study underscores the importance of ongoing research in this field to advance harmonic reduction strategies, making multilevel inverters even more attractive for a wide range of applications.

Design and performance evaluation of multilevel inverter for solar energy systems and electric vehicle charging with multi output active clamp forward converter

This paper addresses the challenges of achieving efficient and high-quality power conversion in solar energy systems and electric vehicle (EV) charging applications by introducing a Multi-Output Active Clamp Forward Converter (MOACFC). The proposed system is designed to generate symmetrical and asymmetrical DC voltage configurations for a Multilevel Inverter (MLI) topology. Traditional MLI topologies often require numerous switches and DC sources, leading to increased complexity and reduced efficiency. To overcome these limitations, the MOACFC delivers multiple output voltages from a single solar generation input, effectively reducing the number of switches and DC sources required. This study also highlights the application of a Recurrent Neural Network Incremental Conductance (RNN-INC)-based Maximum Power Point Tracking (MPPT) algorithm to optimize power extraction from photovoltaic (PV) arrays. The MLI system’s fundamental module can produce 9-level, 21-level, and 31-level outputs, with the Nearest Level Control Pulse Width Modulation (NLCPWM) and Level Shifted Pulse Width Modulation (LSPWM) techniques employed to minimize Total Harmonic Distortion (THD). The results demonstrate significant improvements in power quality, with THD levels reduced to 3.77% in voltage and 0.99% in current for EV charging applications – substantially better than conventional 2-level and 3-level inverters. The findings indicate that the proposed MOACFC-MLI system is a more efficient and reliable alternative, offering enhanced power quality and reduced electrical stress on EV battery systems.

Direct Current Control of Grid Connected Two Level Inverter With LCL-Filter Using Deep Reinforcement Learning Algorithm

Direct Current Control of Grid Connected Two Level Inverter With LCL-Filter Using Deep Reinforcement Learning Algorithm

A Full-Range and High-Dynamic Control Method of Neutral Point Potential for Parallel Three Level Inverters Considering Zero-Sequence Circulating Current

A Full-Range and High-Dynamic Control Method of Neutral Point Potential for Parallel Three Level Inverters Considering Zero-Sequence Circulating Current

LSTM-ANN based DTC of Induction Motor with 5 Level Inverter

LSTM-ANN based DTC of Induction Motor with 5 Level Inverter

Shunt Active Power Filter with Three Level Inverter using Hysteresis Current Controllers

Shunt Active Power Filter with Three Level Inverter using Hysteresis Current Controllers

A Novel Seven Level Inverter with Reduced Switch Count and THD for PV System Applications

A Novel Seven Level Inverter with Reduced Switch Count and THD for PV System Applications