Diode Clamped Multilevel Inverter Research Articles

Power enhancement of transformer less single-phase grid connected solar-wind energy conversion system for various environmental conditions

Abstract This article presents the grid connected hybrid solar-wind energy conversion system (HSWECS) using the cascaded diode clamped multilevel inverter (CDCMLI). The advantage of CDCMLI over the conventional cascaded H-bridge multilevel inverter (CHBMLI) is that the power transfer capacity of the CDCMLI is doubled. The solar and wind energy conversion systems are connected individually to the DC-links of CDCMLI through the DC–DC converter which is used to get maximum power from solar and wind systems. Due to the fluctuating power supply by renewable sources, the isolated DC-links of separate inverters suffer from varying DC-link voltages. A control scheme is proposed which is capable of balancing these DC-link voltages under various power generation scenarios, extracting the maximum possible power from renewable energy sources (RES), and injecting it into the grid at near unity power factor. The proposed control also monitors the power quality of the injected current into the grid. Furthermore, it allows the system to be connected to the grid without any transformer. In addition, mathematical modeling of the CDCMLI has been presented. The performance of the system is analyzed with Matlab/Simulink and confirmed by a prototype model with dSpace 1104.

An Improved Conventional Diode-Clamped Multilevel Inverter Using Non-Zero Triangular- Based Unipolar Modulation Scheme

This paper presents an improved conventional diode-clamped multilevel inverter using non-zero triangular-based unipolar modulation scheme. The proposed scheme is meant to reduce the number of carrier waves, minimize the circuits of modulation scheme and obtain stabilized output voltage waveforms. Non-zero triangular-based unipolar modulation scheme is actualized by using two zero-free triangular wave carriers and two modulating sinewaves for line-to- line five level output voltage waveforms in single phase full bridge diode-clamped multilevel inverter unlike conventional multicarrier sinusoidal pulse width modulation that uses four triangular waves and one modulating sinewave for the same inverter type. The proposed system also used microcontroller in the combinational of its wave signals in order to generate the appropriate triggering signals for switching the power semiconductor switches. The proposed system has the following features: (i) It produces two distinct triggering trains (W1 and W2) meant to reduce the low and high harmonics unlike conventional modulation techniques (ii) All its carrier waves operate in continuous current mode which makes it unique from other multicarrier and other related modulation schemes (iii) it has low component counts. The proposed scheme on the conventional diode-clamped inverter produced the following results: voltage and current with total harmonic distortions of 0.4547%, stabilized 400V output voltage and 20A output current, probability results at each level of voltage and current occurrences are 0.10, 0.25, 0.25, 0.75 and 0.90; power output of 80kW, low component counts of modulation circuit scheme and experimental prototype.

Solar Photovoltaic System-Based Reduced Switch Multilevel Inverter for Improved Power Quality

This paper deals with a reduced switch multi-level inverter for the solar photovoltaic system-based 127-level multi-level inverter. The proposed technique uses the minimum number of switches to achieve the maximum steps in staircase AC output voltage when compared to the flying capacitor multi-level inverter, cascaded type multilevel inverter and diode clamped multi-level inverter. The use of a minimum number of switches decreases the cost of the system. To eliminate the switching losses, in this topology a square wave switch is used instead of pulse width modulation. Thereby the total harmonic distortion (THD) and harmonics have been reduced in the pulsating AC output voltage waveform. The performance of 127-level MLI is compared with 15 level, 31-level and 63-level multilevel inverters. The outcomes of the solar photovoltaic system-based 127-level multi-level inverter have been simulated in a MATLAB R2009b environment.

Switching Sequence Control 31-Level Asymmetric Cascaded of Reduced Switch Count Multilevel Inverter with Multi Carrier Pulse Width Modulation

Various pulse width modulation techniques, including as cascaded multilevel inverters (MLI), diode clamped multilevel inverters, and flying capacitor multilevel inverters, can be used to simply operate common inverters. Due to increased switching losses, current MLIs cannot reach high efficiency. Due to lower losses and THD than standard MLI topologies, the asymmetric cascaded multi-level H-bridge inverter architecture examined in this white paper employs fewer switches and more output voltage levels (Total Harmonic Distortion). The THD is less than the IEEE standard because of the suggested architecture. In this instance, phase difference (PD) multi-carrier PWM techniques are used to control the gate pulses using sinusoidal reference. Each switch receives a different pulse pattern thanks to a method of decimal-to-binary conversion. It is possible to utilise the suggested circuit for applications requiring moderate to high power, and it is quite simple to evaluate. Utilize the MATLAB/SIMULINK environment to simulate time-domain behaviour for the 31-level and 33-level multilevel inverter topologies.

A novel control topology for grid‐integration with modular multilevel inverter

This paper presents a novel control topology for a multilevel inverter with reduced number of power switches for achieving an increased number of levels in output voltage along with improved power quality. The diode clamped multilevel inverter configuration is modified and the gating signals are generated using selective harmonic optimization technique at fundamental frequency using Satin Bower Bird optimization (SBO). It enhances the quality of output voltage waveform with the reduction in total harmonic distortion (THD), less switching power losses, and better efficiency. The inverter is investigated for its competent operation capability on grid-tied applications. Detailed simulation is conducted and results are presented for various load conditions. To validate the inverter operation, an experimental setup of the modified diode clamped modular inverter (MDCMI) interfacing the grid is presented. The loss analysis is carried out at the inverter and converter segments. Based on the analysis, the proposed control topology demonstrates the reliable and efficient operation of the modular inverter. From the results obtained it is evident that the proposed inverter design suits superlative for the grid applications.

Simulation of Different Third Harmonic Injected PWM Strategies for 5-Level Diode-Clamped Multilevel Inverter

Multilevel Inverters (MLI) have widespread use in industrial drive applications, HVDC transmission with Uninterruptable Power Supply systems. They also have applications in the stand-alone and the grid connected renewable energy systems. Multi-level Inverters also find optimum application in Stand-alone and Grid-connected Systems. Majority of losses i.e. switching losses are considered with constrained device rating, the traditional two-level inverters face limits especially when operating at high frequency. The solution which is optimum and appropriate by many power quality researchers is the use of MLIs. Among various MLI topologies the Diode-Clamped Multilevel Inverter (DCMLI) give a promising solution as they can give better voltage performance for different switching frequencies and an improved total harmonic distortion (THD) profile without the use of filter. To meet the voltage and frequency requirement various modulation techniques are applied to MLIs. The additional switching states created by these topologies provide greater flexibility to control more circuit breakers. This paper presents the comparison of a 5-level DCMLIs with several modulation schemes. The simulation results are discussed in detail and the comparison table is presented in terms of Output voltage and THD.

Solar PV-Wind System Integration with Power Grid System

This paper describes a photovoltaic (PV) and wind hybrid power system that is equipped with a Diode Clamped Multi-Level Inverter and LC filter for the generation of renewable energy. Due to their environmental friendliness and availability, wind and solar energy are ideal for hybrid systems in India. Due to fluctuations in the output voltage, equipment that require a consistent supply will be damaged by hybrid power systems that are completely dependent upon intermittent renewable energy sources. Matlab Simulink is used to create a model of the hybrid system using a Diode Clamped Multi-Level Inverter and an LC filter. Before merging a DC voltage hybrid system with the main grid of the power system, blocks such as the wind model, solar model, Diode Clamped Multi-Level Inverter, and LC filter are developed independently.... The input parameters for the project simulation include different irradiance values and varied wind speeds. Initially, a DC voltage hybrid system with the main grid of power system is constructed separately, taking into account the characteristics of the wind and photovoltaic models developed, as well as the simulation results for hybrid systems with and without Diode Clamped Multi-Level Inverters and LC filters. The input parameters for the project simulation include different irradiance values and varied wind speeds. Present are the wind and photovoltaic model characteristics, as well as simulation results for a hybrid system with and without a Diode Clamped Multi-Level Inverter and LC Filter. The results suggest that hybrid systems are more reliable in terms of generating output voltage than solo systems in this study. As well as this, the hybrid system's Diode Clamped Multi-Level Inverter and LC Filter can reduce output voltage fluctuations.

Dual Control of Asynchronous Motor for EV Fed by 5-level Diode Clamped Multilevel Inverter using SPWM Technique

This paper presents the discussion about the working principle and simulation of three phases Induction Motor (IM) for electric vehicle fed by five level diode clamped multilevel inverter. Multilevel inverter technology has emerged recently as a very important alternative in the area of EV system. The main objective of this paper is to control the speed of an IM by using 5-level diode clamped multilevel inverter. To obtain high quality sinusoidal output voltage with reduced harmonics, multicarrier PWM control scheme is proposed for diode clamped multilevel inverter. A speed control and torque control can be achieved by using sinusoidal output voltage which has high quality by multicarrier Sinusoidal Pulse Width Modulation (SPWM) technique. The planned system is best progress in production of towering switching losses results compared with other conventional method. The proposed system is an effective replacement for the conventional method which produces high switching losses and results in poor drive performance. The simulation results reveal that the proposed circuit effectively controls the motor speed and enhances the drive performance through reduction in total harmonic distortion. Also this shows that the planned method controls the speed and torque of motor in efficient manner. Hence, the system usefulness is established through simulation.

THD Analysis on a Single Phase 7-Level Diode Clamped MLI with LC Filter Based on Multicarrier Anti-Phase SPWM Technique

Inverter is an electronic device which is an important part to convert DC-AC energy. Increased use of renewable energy as a substitute for fossil energy that is running low encourages the increased performance of the inverter. Multilevel inverter offer many advantages for improving the performance of an inverter system. Diode Clamped Multilevel Inverter are explored with 7-level circuits that are analyzed and simulated specifically on the quality of the output ie the amount of harmony. The power switch control technique uses Anti-Phase SPWM with multicarrier. Further to maximize damping harmonics, LC filter is applied and researched. This research is using PSpice A / D Lite to simulate a system that worked. The results obtained harmonic attenuation reached 3.93% after LC filter.

Design and Analysis of STATCOM for Reactive Power Compensation using Three Phase Multilevel Inverter

This paper proposes the concept of reactive power compensation with the aid of STATCOM (static synchronous compensators) and three phase multilevel inverter. The classification of multilevel inverters under three major types which are H-bridge inverter, flying capacitors-based inverter and diode clamped multilevel inverter. Among these multilevel inverters, the diode clamped type is stressed in this paper due to its capability to process 3-phase output in the absence of any input. Here the reactive power is compensated using 7-level based multilevel inverter with diode clamps are made utilizing the capacitors banks, diodes and switches which would therefore abates the voltage stresses and harmonics resulting in higher efficiency of the power system. Besides the functioning of multilevel inverter, STATCOM is also utilized to improve the regulation of reactive power flow and thereby, enhances the stability under transient condition of a power system. Subsequently, the compensated seven level output is procured by the sinusoidal PWM technique.

Logic‐based space‐vector modulation for neutral‐point‐clamped multilevel inverter with DC‐link voltage balancing capability

This study proposes a new simple and fast space-vector modulation scheme with the capability of balancing capacitor voltages in neutral-point-clamped converters. In the first step, transformations from the commonly used reference frames to the 60°-frame are discussed. Next, a new method is presented to generate an appropriate switching sequence based on the voltage of the clamp point and direction of the phase currents. The proposed method is computationally efficient and its algorithm only needs knowledge of the load current directions, leading to further simplification of the hardware. This method can easily be generalised to control diode-clamped multilevel inverters with an arbitrary number of levels. The feasibility, effectiveness, and performance of the method are investigated through simulation and experimental studies under various load conditions.

Design and Analysis of Dual Output Three Level Inverter with Reduced Switch Count Topology

The multilevel inverter is widely used for medium voltage and high power applications. However, the application is limited due to the need for more number of switches, diodes and the system complexity. The proposed inverter is a hybrid topology with two-level and three-level diode clamped multilevel inverter structure with a reduced number of switches, diodes and gate driver circuits for dual output, which reduces system cost and complexity. In general, diode clamped multilevel inverter needs 24 switches to control dual output. In this paper, it was reduced as 15 switches and 12 switches by sharing of middle switches. The simulation was carried out by MATLAB Simulink and the hardware results were compared with simulation results. Also, modulation index, switching frequency and different topology with R, and RL loads were discussed and compared. The experimental plan was developed as per the Box–Behnken method and the experiments were carried out. The results were statistically analyzed and its significance was tested.

Full Range Capacitor Voltage Balance PWM Strategy for Diode-Clamped Multilevel Inverter

This paper briefly reviews virtual space vector pulse width modulation (VSVPWM) for the diode-clamped multilevel inverter (DCMLI). Based on the universal modulation model of the DCMLI with N-level, a modulation strategy named as full range capacitor voltage balance PWM (FRCVBPWM) is proposed, which has similar capacitor voltage balance characteristics as VSVPWM. The characteristic of FRCVBPWM is that there are respectively zero, N − 1 and N − 2 switching actions for the three phases of the DCMLI. Therefore, the total switching actions are greatly decreased compared with VSVPWM. The switching loss comparison between FRCVBPWM and VSVPWM is conducted by comprehensive simulations. Finally, the feasibility and superiority of FRCVBPWM over VSVPWM is verified by experiments.

Nonconventional Diode Clamped Multilevel Inverter with Reduced Number of Switches

The conventional multilevel inverter (MLI) is divided into three types: diode clamped MLI, cascade H Bridge MLI and flying capacitor MLI. The main disadvantage of these types is the higher required number of components when the number of the levels increases and this results in more switching losses, system higher cost, more complex of control circuit as well as less accuracy. The work in this paper proposes two topologies of nonconventional diode clamping MLI three phase nine levels and eleven levels. The first proposed topology has ten switches and six diodes per phase while the second topology has nine switches and four diodes per phase. The pulse width modulation (PWM) control method is used as a control to gate switches. THD of the two proposed topologies are analyzed and calculated according different values of Modulation index (where the power loss and efficiency are obtained and plotted.

Novel Hybrid Pulse Width Modulation Technique for Solar Fed Cascaded Multilevel DC-Link Inverter

Multilevel inverter plays an important role especially in solar based renewable energy sources due to its modularity in structure and medium or high power applications. It is well known that there are three types of inverters which are Diode clamped multilevel inverter, flying capacitor multilevel inverter and cascaded multilevel inverter. One of the drawback of these inverters are, more switching losses due to which quality of power get decreases. The main intention of this work is to improve the quality of power, thereby increasing the life and performance of the overall system at consumer side. One of the reduced switched multilevel inverters have been used to perform so called multilevel DC link inverter. In earlier days, Sinusoidal Pulse Width Modulation (SPWM) technique is used to reduce the switching losses of the inverter. Present work proposes a new Hybrid Pulse Width Modulation (HPWM) technique to control the switching losses in the system. In this HPWM technique, multi level DC link inverter having combination of SPWM (at level generation), and Fuzzy controller(at polarity generation) are used to reduce the losses, and the results are compared with conventional SPWM technique considering R and R-L load.

Asymmetric diode-clamped multi-level inverter based renewable power generation system

ABSTRACT In this paper, a grid-connected power conversion topology is developed to convert a DC power from the renewable energy into a high-quality AC power. This grid-connected power conversion topology consists of an asymmetric diode-clamped multi-level inverter (DCT-MLI) and a dual-output DC-DC power converter. The asymmetric DCT-MLI includes two diode-clamped arms, two DC capacitors, and a filter inductor. The novelty of proposed asymmetric DCT-MLI is that the voltages of the two DC capacitors are in a multiple relationship. As a result, the asymmetric DCT-MLI will generate an AC voltage with more voltage levels by the power circuit similar to the symmetric DCT-MLI, and the capacity of filter inductor is further reduced. The dual-output DC-DC power converter combines a boost converter and a charge pump circuit to generate two DC voltages in a multiple relationship to supply the asymmetric DCT-MLI. The salient feature is that only a power electronic switch is used in the dual-output DC-DC power converter such that the control circuit is simplified. A hardware prototype is set up to verify the performances of the proposed grid-connected power conversion topology.

Unified Power Quality Conditioner using PV Fed SVPWM based Multilevel Converters for Power Quality Improvement

This paper presents a solar photovoltaic based unified power quality conditioner (PV-UPQC). The proposed system consists of a shunt compensator (ShC), series compensator (SeC) and PV array connected in parallel to a common dc-link. A three-level diode clamped multilevel inverter configuration is used as shunt and series converters. The SVPWM technique provides reduction in the common mode voltage and the balancing of the dc link voltage. The shunt compensation converter extracts power from PV array and provides compensation for load harmonic currents. The series compensation converter compensates for the power quality (PQ) problems such as grid voltage sags/swells and source harmonic voltages. The proposed system utilizes space vector pulse width modulation (SV-PWM) in multilevel converter topology for the mitigating the power quality problems using PV-UPQC. The proposed system improves PQ and also utilize RES, it also simultaneously improves both current and voltage disturbances. The performance of the system is analyzed in MATLAB/Simulink for nonlinear load conditions.

Decoupled Power Flow Control of a Single Stage Grid Connected Pv System With Multilevel Inverter

With the wide installation of solar PV array in respect of other renewable power generation, there is a scope of feeding the surplus power to grid for better and economic power utilisation. The foremost objective of this paper to independent regulation of real and reactive power flow of single stage grid coupled PV system using multilevel inverter. Vector control scheme has been implemented in direct and quadrature reference frame which is synchronously rotating with the frequency of the grid. Two current control loop has been used, one for d-axis and other for q-axis to regulate the current inserted into the grid such that it has low total harmonic distortion and in phase with the grid voltage. In addition to that, a DC voltage control loop has also been implemented to operate the inverter at the desired DC link voltage that is the DC voltage corresponding to maximum power, which is obtained by the MPPT algorithm. Grid coupled inverters have extensive usage in the area of distributed generation and power eminence improvement. The above scheme employs a three-phase three-level Diode clamped multilevel inverter to improve the current injected to grid.

Theoretical Analysis of LC Filter to Three Level Diode Clamped Inverters in Low/Medium Voltage Applications

The employing of power electronic devices for converters plays a vital role in the conversion of AC to DC vice versa. Applications of these converters more demand in renewable energy, hybrid vehicles, Drives, HVDC, etc. In renewable energy, especially a solar-based power generation stations require inverter stations. These inverters stations have the multilevel inverters. Multilevel inverters are emerging day by day in the sector of the renewable energy sector. The increasing level of multilevel inverters can be effectively utilized in low and medium voltage applications to get the desired voltage and frequency. But output voltage is not in sinusoidal. However, most of the loads require a pure sinusoidal form of voltage. To get sinusoidal voltage across loads a high switching frequency is required to switch the MOSFETs or IGBTs. Along with a suitable value of LC, filters make the sinusoidal nature of waveform with less total harmonic distortion (THD) levels. To get a sinusoidal wave, a proper theoretical analysis of filters is required. In this paper theoretical analysis has been done for LC filters and checked with simulation results for various loads. The performance of theoretical LC filters values checked using diode clamped multi-level inverters have been examined through MATLAB/SIMULINK by POD PWM by POD PWM.

Enhancing the Performance of Multilevel Inverters using Modified SVPWM Techniques

In this paper, two types seven-level multilevel inverters in three phase configuration, Cascaded H-bridge Multilevel Inverter (CMLI) and Diode Clamped Multilevel Inverter (DCMLI) are simulated and compared the results for three different carrier PWM techniques. Here, Carrier based Sinusoidal Pulse Width Modulation (SPWM), Third Harmonic Injected Pulse Width Modulation (THIPWM) and Modified Carrier-Based Space Vector Pulse Width Modulation (SVPWM) are used as modulation strategies. These modulation strategies include Phase Disposition technique (PD), Phase Opposition Disposition technique (POD), and Alternate Phase Opposition Disposition technique (APOD). In all the modulation strategies, triangular carrier and trapezoidal triangular carrier signals are compared with reference signal for generation of control pulses. The simulations have been carried out for seven-level CMLI and DCMLI using MATLAB/Simulink. The detailed analysis of results in terms of %THD and utilization of DC-link voltage has been presented in this paper. By increasing the performance of inverters the utilization of input energy is reduced, then the corresponding energy sources can be reduced.