In-phase Disposition Research Articles

A novel in-phase disposition SPWM pulse allocation strategy for cascaded H-bridge inverter

A novel in-phase disposition SPWM pulse allocation strategy for cascaded H-bridge inverter

Effect of supply voltage variations on single-phase capacitor clamped multilevel inverter fed induction motor drive

This article presents the effect of supply voltage variations on single-phase capacitor-clamped multilevel inverter-fed induction motor drives. This research is tailored at determining the best torque value and speed to attain a stable state under input voltage variation and minimum time response to realize low percentage harmonic distortions. The effect of constant power quality disturbance harms the performance and behavior of asynchronous motors based on harmonic contents and other energy source integrations. The multilevel inverter has shown good performance in motor drives. This paper deals with the effect of input voltage variations on a single-phase multilevel capacitor-clamped inverter for asynchronous induction motor drives. A five-level capacitor-clamped inverter with an in-phase disposition pulse width modulation technique is adopted. Four high-frequency triangular carrier signals are generated and compared with a reference sinusoidal signal. As a result of this approach, the inverter switches firing signals are generated. The open-loop model is designed and simulated utilizing MATLAB/Simulink and results based on different values of supply voltage are presented. The current and voltage total harmonic distortions (THDs) obtained are 4.97% and 4.46% respectively at the best operating voltage of 400 V and at maximum torque of 47 Nm.

Comparative performance of modular with cascaded H-bridge three level inverters

<span lang="EN-US">The conventional two-level inverter becomes no longer has the ability to cope with the high-power requirement, so this paper discusses two very common topologies of multilevel inverter like modular multi-level converter (MMC) and cascaded H-bridge (CHB) multi-level inverter for induction motor drive applications. This work attempts to investigate the comparison between MMC and CHB. The comparison is done in aspects of the configuration, concept of operation, advantages and disadvantages, the comparison is also consider output voltage (line to line) waveform, total harmonic distortion (THD) of the output line voltage waveform and the current drawn by both inverters. The performance of the inverters under carrier-based pulse width modulation (PWM) technique and mainly in-phase disposition (IPD), level shifted pulse width modulation is viewed. The paper discusses the comparison between the two multilevel inverters (MLIs) with motor drive applications especially induction motor. The operation of the motor is studied under certain value of load torque. The simulation results for the induction motor with the two inverters (modular multi-level and Cascaded H-bride) for three numbers of levels using MATLAB/Simulink are provided). The obtained results are encouraging and promising especially in the improvement of the THD% results.</span>

Level-Shift PWM Control of a Single-Phase Full H-Bridge Inverter for Grid Interconnection, Applied to Ocean Current Power Generation

A small prototype of a 5-level single-phase full H-bridge inverter for ocean current applications is presented. The inverter was designed applying level-shift control in pulse-width modulation (LS-PWM), and experimental tests were conducted using a variety of modulation subschemes, including in-phase disposition (IPD), alternate-phase opposition–disposition (APOD), and phase opposition–disposition (POD). The test results were examined for harmonic content and voltage total harmonic distortion (THDV). The results suggest that the inverter presents a viable solution with significant potential for the development of a larger three-phase inverter model that can be used to connect ocean current power sources to the electrical grid.

Pulse Width Modulation Analysis of Five-Level Inverter- Fed Permanent Magnet Synchronous Motors for Electric Vehicle Applications

In recent times, intense research has been focused on the performance enhancement of permanent magnet synchronous motors (PMSM) for electric vehicle (EV) applications to reduce their torque and current ripples. Permanent magnet synchronous motors are widely used in electric vehicle systems due to their high efficiency and high torque density. To have a good dynamic and transient response, an appropriate inverter topology is required. In this paper, a five-level inverter fed PMSM for electric vehicle applications, realized via co-simulation in an electromagnetic suite environment with a reduced stator winding current of PMSM via the use of in-phase disposition (PD) pulse width modulation (PWM) techniques as the control strategy is presented. The proposed topology minimizes the total harmonic distortion (THD) in the inverter circuit and the motor fed and also improves the torque ripples and the steady-state flux when compared to conventional PWM techniques. A good dynamic response was achieved with less than 10A stator winding current, zero percent overshoot, and 0.02 second settling time synchronization. Thus, the stator currents are relatively low when compared to the conventional PWM. This topology contribution to the open problem of evolving strategies that can enhance the performance of electric drive systems used in unmanned aerial vehicles (UAV), mechatronics, and robotic systems.

Modified SPWM technique for improved harmonic performance of single PV array fed grid‐tied five‐level converter

This study presents a performance assessment of a single photovoltaic (PV) array fed transformer-based five-level converter topology with optimal shift factor-based modified sinusoidal pulse width modulation (OSF-MSPWM) technique under a dynamic solar PV environment. The five-level converter output is generated using H bridge cells and single-phase transformers. A single PV array is fed to all cascaded H bridge cells and isolation is provided by cascading secondary windings of the transformers in the AC side. The separate DC sources requirement is eliminated and galvanic isolation is provided by single-phase transformers. The decoupled controller with modified in-phase disposition PWM technique is used for active power injection into the grid at unity power factor. This work uses a new carrier shape at the same input carrier frequency and modulation index m f for improving the harmonics performance of the five-level converter. Hence, shift the dominant harmonics to the higher side for developed topology and performing optimal shift factor-based modulation is compared with the conventional SPWM technique. The steady-state and dynamic responses of the PV multilevel converter are observed in MATLAB simulation and tested in a real-time platform.

Comparative Analysis of Multi-carrier PWM Methodologies for 3-Phase 9-Level Cascade Inverter

This work puts forth the comparative analysis of multi-carrier pulse width modulation (PWM) methodologies for 9-level cascaded H-bridge inverter. Multilevel inverters (MLIs) have many advantages over traditional inverters, especially for high power applications. The cascade-connected H-bridge multilevel inverters use capacitors and devices, requiring fewer components per level. Different sinusoidal PWM technologies are used to generate correlation pulses which control the converter switching. The simulation results show the relative performance of different multi-carrier PWM techniques in respect of output voltage waveforms. From the results, it is observed that in phase disposition (IPD) technique provides better performance and produces a substantially sinusoidal output voltage waveform vis-a-vis phase opposite disposition (POD) and alternate phase opposite disposition (APOD) techniques. Further, the total harmonic distortion (THD) is also reduced significantly and effective responses are obtained under varying modulation index.

Investigation of three‐level NPC‐q Z S inverter‐based grid‐connected renewable energy system

The neutral point clamped quasi-Z-source (NPC-qZS) inverter is poised to become a potential candidate for renewable energy applications because it yields a continuous input current and voltage boost. In this study, the closed-loop control of grid-tied three-phase (3- ϕ ) NPC-qZS inverter, fed with renewable energy sources, is proposed for the first time. A dynamic model has been developed to accurately design the control strategy. The proposed strategy includes the control of grid-tied current and the peak dc-link voltage (PDV). The control of grid-tied current is achieved through a damped-second-order-generalised integrator. The PDV is estimated indirectly from the voltages of qZS network capacitors and is regulated by an integral-double-lead controller. Two modified modulation techniques based on phase-opposite disposition and in-phase disposition are proposed to yield shoot through by injecting 3rd harmonics for maximum constant boost control. A comparison is drawn between the performance of the proposed controller and sliding-mode controller on the dc side. The controller design and system performance are validated through real-time simulation and experimentation on a practical setup in the laboratory.

Space vector PWM algorithm for a three‐level asymmetrical six‐phase motor drive

A space vector pulse-width modulation (SVPWM) algorithm for a three-level asymmetrical six-phase drive based on vector space decomposition (VSD) approach is presented in this paper. A modification in zero plane of the transformation matrix is proposed in order to meet the requirement that the realisation of sinusoidal output phase voltages can be obtained through the chosen output leg voltage space vectors. Furthermore, a method of choosing the switching sequences based on all possible one-level transitions of the leg voltages, i.e. a permutation method, is introduced. The algorithm is then validated experimentally and obtained results show that the developed method successfully achieves the desired fundamental phase voltage, although low order harmonics are present due to uncompensated inverter dead time. Last but not least, the performance of the proposed SVPWM algorithm is compared to several carrier-based PWM algorithms including in-phase disposition with ‘double min-max injection’ (PD-DI). This is a little known type of injection, which is verified to obtain identical performance as the presented multilevel algorithm.

Fuzzy Logic Control of SLMMC-Based SAPF Under Nonlinear Loads

This work proposes fuzzy logic controller (FLC) for seven-level modular multilevel converter (SLMMC)-based shunt active power filter (SAPF) to reduce harmonics in source current. Half-bridge submodule is proposed for SLMMC due to its simple configuration and low conduction losses. An instantaneous real and reactive power (IPQ) method is proposed to extract reference currents. The multicarrier-based in-phase disposition (IPD) pulse width modulation method is proposed to control the switches in efficient approach. The performance of FLC in SLMMC and seven-level cascade H-bridge SAPF is verified in terms of harmonic reduction under nonlinear loads. The capacitor voltage balancing is achieved using the proposed FLC. The proposed work is simulated using MATLAB/Simulink software package.

Active Harmonic Filtering Using Multilevel H-bridge Inverter Based STATCOM

This paper proposed three-phase multilevel cascaded H-bridge inverter (MCHI) based active harmonic filtering (AHF) compensator, or refer to as static synchronous compensator (STATCOM), to minimize the harmonic components in a transmission network. There are three main elements to form a STATCOM, namely: control scheme, modulation technique and inverter topology. In this work, the synchronous reference frame (SRF) based controller is designed and implemented to produce the desired modulating signals (i.e., one for each phase) for the pulse width modulation (PWM) module. For simplicity, the carrier based pulse width modulation (CBPWM) with in phase disposition (IPD) technique is employed to generate the pulse trains and drive the three-phase five-level CHI. On the other hand, two three-phase non-linear loading conditions, which structured by different transformer winding configurations and power rectifier circuits, are utilized to verify the feasibility of the proposed AHF. The effectiveness and the theoretical prediction of the proposed approach is investigated and validated through simulation studies using MATLAB SIMULINK software package.

Comparison of Seven and Nine Level Flying Capacitor-Multilevel Inverter using Staircase and Stepped Modulation

In this paper, a seven-level and nine-level flying capacitor inverter (FLI) is modeled and simulated. For the control of the switches, distinct multicarrier PWM strategies such as In Phase Disposition (IPD) PWM, Phase Opposition Disposition (POD) PWM and Alternative Phase Opposition Disposition (APOD) PWM are implemented by considering three reference signals, namely sine, step and staircase. Intensive simulation experiments are carried out under matlab/simulink environment and fundamental value and harmonics of output voltages of the seven-level FLI and nine-level FLI under different modulation conditions viz., IPD, POD, APOD are measured and compared. Simulation results illustrates IPD and POD technique gives a better output waveform with lower THD value than APOD technique.

Research on Power-Balance Control Strategy of CHB Multilevel Inverter Based on TPWM

Against to the problems of low utilization rate of DC-side voltage of Cascaded H-bridge (CHB) multi-level inverter Carrier Disposition (CD) modulation strategy and unbalanced output power of each cascaded H-bridge units, a power balanced based In-Phase Disposition Trapezoidal Pulse Width Modulation (IPD-TPWM) strategy is proposed in this article. By selecting an appropriate trapezoidal wave triangulation rate $\delta $ , the modulation strategy can greatly increase the amplitude of the CHB inverter output voltage fundamental wave while ensuring the waveform quality of output phase voltage, and realize the power-balance of H-bridge units within a full modulation ratio range by changing the arrangement of triangular carriers in the vertical direction while using the carrier segment in the half carrier period of the IPD-TPWM strategy as the basic unit. Therefore, it has solved the problem of low utilization rate of DC-side voltage and unbalanced output power of each unit. At the same time, the Total Harmonic Distortion (THD) of output line voltage of the modulation strategy is lower than that of IPD-SPWM strategy in the whole modulation degree, which effectively improves the quality waveform of the output line voltage, and can be conveniently used in N-level CHB inverters. Moreover, the working stress of all the unit switching tubes is the same, the heat dissipation distribution is uniform, the switching loss is effectively reduced, and the service life and system reliability are improved. Finally, the Matlab/Simulink simulation model and experimental platform are established to verify the validity and practicality of the modulation strategy.

Hybrid Multi-Carrier PWM Technique Based on Carrier Reconstruction for Cascaded H-bridge Inverter

In response to the deficiencies that the Carrier Phase Shift (CPS-PWM) and Carrier In-Phase Disposition (IPD-PWM) modulation techniques are applied to Cascaded H-bridge (CHB) multilevel inverters, combined with the advantages of the two techniques, a Hybrid Multi-carrier PWM technique based on carrier reconstruction is proposed. The aforementioned technique uses the carrier segment in the half carrier period of the IPD-PWM technique as the basic unit and optimizes the modulation performance by periodically adjusting its arrangement in the vertical direction. When CHB multilevel inverter adopts Hybrid Multi-carrier PWM technique, as with CPS-PWM technique, the output power balance between the cascaded H-bridge cells is achieved naturally; at the same time, the harmonic spectrum of the output voltage is identical with that of the IPD-PWM technique, that is to say, the harmonic characteristics of the output line voltage of the inverters are effectively improved. In this paper, the CHB seven-level inverter is taken as an example, and the correctness of the relevant conclusions is verified by simulation and experimental results.

Design and Hardware Implementation Considerations of Modified Multilevel Cascaded H-Bridge Inverter for Photovoltaic System

Inverters are an essential part in many applications including photovoltaic generation. With the increasing penetration of renewable energy sources, the drive for efficient inverters is gaining more and more momentum. In this paper, output power quality, power loss, implementation complexity, cost, and relative advantages of the popular cascaded multilevel H-bridge inverter and a modified version of it are explored. An optimal number of levels and the optimal switching frequency for such inverters are investigated, and a five-level architecture is chosen considering the trade-offs. This inverter is driven by level shifted in-phase disposition pulse width modulation technique to reduce harmonics, which is chosen through deliberate testing of other advanced disposition pulse width modulation techniques. To reduce the harmonics further, the application of filters is investigated, and an LC filter is applied which provided appreciable results. This system is tested in MATLAB/Simulink and then implemented in hardware after design and testing in Proteus ISIS. The general cascaded multilevel H-bridge inverter design is also implemented in hardware to demonstrate a novel low-cost MOSFET driver build for this study. The hardware setups use MOSFETs as switching devices and low-cost ATmega microcontrollers for generating the switching pulses via level shifted in-phase disposition pulse width modulation. This implementation substantiated the effectiveness of the proposed design.

Decoupled PWM Control of a Dual-Inverter Four-Level Five-Phase Drive

This paper studies pulse-width modulation (PWM) techniques suitable for a four-level five-phase open-end winding (OeW) drive. The drive comprises a five-phase induction machine, supplied using two two-level voltage source inverters (VSIs) with isolated and unequal dc-link voltages, in the ratio 2:1. A decoupled carrier based (CB) PWM modulation strategy, based on unequal voltage reference sharing between the two converters, is introduced in this paper. The stability of dc-link voltages in OeW drives is investigated next, using a novel analysis technique. Several modulation methods are analysed and the results show that application of the coupled pulse width modulation technique, with carriers having in-phase disposition (PD), leads to overcharging of the capacitor in the dc-link of the inverter intended to operate with the lower dc-link voltage. On the other hand, the proposed decoupled CB PWM scheme naturally eliminates the dc-link capacitor overcharging problem. These findings are verified experimentally, using open-loop V/f control. Two different decoupled CB modulation methods are compared and the best performing modulation method is selected and incorporated further into an OeW drive with field-oriented control (FOC). The presented steady state and transient experimental results demonstrate that the decoupled CB PWM technique is suitable for high performance variable speed drive applications.

Analysis of an ideal dual‐impedance network using reference disposition modulation

A single-impedance network consists of two inductors and capacitors connected in an X-shape to provide single-stage energy conversion. This structure eliminates the need for two-stage energy conversion that is currently employed in traditional converters. A dual-impedance network includes two individual sets of inductors and capacitors connected in parallel. This network possesses the flexibility of using two different sources as inputs to meet the load demand. In order to provide voltage boosting, the switching must be performed selectively to shoot-through (ST) the power sources. A modified modulation method has been implemented to introduce the ST for switching. The modified modulation method shares the operating principle with the in-phase disposition modulation method for multilevel inverters. However, the reference signals are dispositioned via the modified modulation method rather than employing carrier disposition via the traditional modulation methods. Therefore, the circuit analysis of a dual-impedance network is evaluated whose switching is achieved by a modified modulation method for an ideal condition. The simulations are carried out using the MATLAB/PSIM environment and the results are presented.

Minimization of power loss in newfangled cascaded H-bridge multilevel inverter using in-phase disposition PWM and wavelet transform based fault diagnosis

Abstract Nowadays multilevel inverters (MLIs) have been preferred over conventional two-level inverters due to reduced harmonic distortions, lower electromagnetic interference, and higher DC link voltages. However, the increased number of components, complex PWM control, voltage-balancing problem, and component failure in the circuit are some of the disadvantages. The topology suggested in this paper provides a DC voltage in the shape of a staircase that approximates the rectified shape of a commanded sinusoidal wave to the bridge inverter, which in turn alternates the polarity to produce an AC voltage with low total harmonic distortion and power loss. This topology requires fewer components and hence it leads to the reduction of overall cost and complexity particularly for higher output voltage levels. The component fault diagnostic algorithm is developed using wavelets transform tool. Finally an experimental prototype is developed and validated with the simulation results.

Analysis of Reduced Switch Topology Multilevel Inverter with Different Pulse Width Modulation Technique and Its Application with DSTATCOM

Multilevel inverter has played a vital role in medium and high power applications in the recent years. In this paper, Reduced Switch Count Multi Level Inverter structure (RSCMLI) topology is presented with different pulse width modulation techniques. The harmonic level analysis is carried out for the reduced switch count multilevel inverter with the different PWM technique such as with Alternate Phase Opposition Disposition (APOD) method, In Phase Disposition (IPD) method and multi reference pulse width modulation method for five level, seven level , nine level and eleven level inverter. The simulation results are compared with the cascaded H Bridge Multi Level Inverter (CHBMLI). The nine level RSCMLI inverter with APOD method is used for the Distribution Static Synchronous Compensator (DSTATCOM) application in the nonlinear load connected system for power factor improvement. The result shows that the harmonic level and the number of switches required for RSCMLI is reduced compared to CHBMLI. RSCMLI employed in DSTATCOM improves the power factor and harmonic level of the system when it is connected to the nonlinear load.

Modeling of a Multilevel Voltage Source Converter Using the Fast Time-Domain Method

Power system harmonics can increase system loses, excite resonant frequency, and cause equipment damage. It is, therefore, essential to develop accurate harmonic models for harmonic sources, such as power converters. During the last decades, renewable energy sources have become an important part of the worldwide concern with clean power generation. In response to the growing demand for medium and high power trends, multilevel converters (MCs) have been attracting growing considerations. As they become more spread out, their harmonic impact on the system could be significant. In this paper, a fast time-domain method (FTDM) suitable for modeling a MC is proposed. The FTDM essentially models the harmonic of interest as a harmonic state and solves it together with the system differential equations. Since the solution is analytical, the FTDM is very accurate. Nevertheless, to model a MC, the FTDM requires to solve a very large exponential matrix. Hence, a Krylov subspace method is proposed to solve for the exponential matrix, resulted from the FTDM. Two case studies on two different modulations (in-phase disposition and phase-shifted modulations) are performed to validate the proposed method with PSCAD/EMTDC. The computation time of the proposed method is much shorter compared to PSCAD/EMTDC and other solvers.