Two-level Voltage Source Inverter Research Articles

Review of Multilevel Level Inverter Using Different Topologies

This paper provides a concise overview of various multilevel inverter (mli) topologies. The conventional two-level voltage source inverter (vsi) necessitates a filter to generate sinusoidal output waveforms, which can be challenging at high frequencies due to switching losses. To address this issue, multilevel inverters offer lower switching frequencies and reduced total harmonic distortion (thd), eliminating the need for filters and large transformers. Moreover, a few advantages of mli inverters are reduced switching losses, better performance at high switching frequencies, and higher power quality (almost pure sinusoidal). Nevertheless, adding to the complexity of the system is the requirement for each switch to have its own gate driver in order to perform mli. Thus, it's imperative to decrease the mli's number of switches. In order to reduce the number of switches needed, this paper reviews some of the various current topologies. Applications such as voltage regulation, var compensation, harmonic filtering in power systems, and user interface for renewable energy have led to the development of cascaded h-bridge multilevel inverters. For solar applications, a modified cascaded h-bridge multilevel inverter (mli) is used. Cascaded h-bridge topology multilevel inverter will aid in reducing the number of switches. Comparing this concept to other multilevel inverters, the switching complexity is reduced.

Bağımsız Bir Hibrit Güç Sisteminin Tasarımı ve Akıllı MPPT Algoritmaları ile Optimizasyon Kontrolü

In this paper, a stand-alone hybrid power system has been proposed using both: photovoltaic generator (PVG) and permanent magnets synchronous generator (PMSG), integrated with a lithium-type battery connected to the DC bus. The improvement of performance and reliability of the overall system are guaranteed. For this aim, the efficiency of the PVG system can be enhanced firstly by using two MPPT's techniques, such as the Perturb and Observe (P&O) method and the Fuzzy Logic Control (FLC) approach. The Genetic Algorithms (GA’s), using the principles of evolution, natural selection, and genetic mutation, are then introduced to address difficulties in the adjustment of the FLC gains. A lithium-ion battery model is presented to ensure stability and energy storage. Furthermore, the model of the wind energy conversion system (WECS) based on PMSG is presented. Hence, the control by the gradient method, allowing designing an MPPT based on the delivered power and mechanical speed of the generator. Both sources are connected to the grid via a two-level voltage source inverter controlled by Space Vector Modulation (SVM) technique. Finally, simulation results obtained using MATLAB / SIMULINK software proved the effectiveness of proposed control strategies with high performance which is manifested clearly when the suggested controllers employed and shed light on the performance of the stand-alone hybrid system.

Diagnosis of Multiple Open-Circuit Faults in Three-Phase Induction Machine Drive Systems Based on Bidirectional Long Short-Term Memory Algorithm

Availability and continuous operation under critical conditions are very important in electric machine drive systems. Such systems may suffer from several types of failures that affect the electric machine or the associated voltage source inverter. Therefore, fault diagnosis and fault tolerance are highly required. This paper presents a new robust deep learning-based approach to diagnose multiple open-circuit faults in three-phase, two-level voltage source inverters for induction-motor drive applications. The proposed approach uses fault-diagnosis variables obtained from the sigmoid transformation of the motor stator currents. The open-circuit fault-diagnosis variables are then introduced to a bidirectional long short-term memory algorithm to detect the faulty switch(es). Several simulation and experimental results are presented to show the proposed fault-diagnosis algorithm’s effectiveness and robustness.

Low Complexity Model Predictive Flux Control Based on Discrete Space Vector Modulation and Optimal Switching Sequence for Induction Motors

In this paper, a low-computational burden model predictive flux control (MPFC) based on discrete space vector modulation (DSVM) and the optimal switching sequence (OSS) is proposed for achieving switching frequency (SF) and computational burden efficiencies in motor drives fed by two-level voltage source inverter. The DSVM is used to extend the prediction candidates of MPFC and greatly improve the performance of the controller. A generalized minimum flux error method independent of the number of virtual vectors is derived to cancel the exhaustive optimization method and lower the execution time of the proposed algorithm. In addition, new over-modulation and OSS schemes are designed to optimize the use of DC-link voltage and mitigate the inverter SF when implementing the optimal control action into switching states. The comparative experimental results show that without significant performance degradation, the proposed strategy provided about 50% SF and 25% execution time reductions compared to the classic MPFC methods.

An Improved Mutated Predictive Control for Two-Level Voltage Source Inverter With Reduced Switching Losses

An Improved Mutated Predictive Control for Two-Level Voltage Source Inverter With Reduced Switching Losses

Synchronous Generator Feeding DC Grid Having Brushless Excitation System With Induction Machine Operating in Deep Plugging Mode

This paper proposes a novel excitation control for a recently proposed synchronous generator (SG) entitled Brushless Induction Excited Synchronous Generator (BINSYG) for wind energy applications. In BINSYG, one SG and another Induction machine (IM) are embedded in the same machine frame to make the overall system brushless. Here, IM acts as the excitation machine and regulates the dc excitation for SG by rectifying the rotor-induced currents through a rotating rectifier. SG feeds power to dc grid via a two-level six-switch Voltage Source Rectifier that is operated at unity power factor at the SG terminal. The excitation developed by IM is regulated using a new frequency modulation control strategy for a two-level Voltage Source Inverter connected to the stator of IM. The excitation machine helps operate SG at variable wind speeds with reduced flux distortions. The proposed system is speed/position sensorless and controlled without using any voltage or current sensors on the IM side. The system with its proposed control algorithm is modeled in MATLAB/Simulink and experimental verification for a small-scale laboratory prototype BINSYG feeding power to a 220 V dc grid are presented to validate the effectiveness of the controller.

Enhancing the Performance and Efficiency of Two-Level Voltage Source Inverters: A Modified Model Predictive Control Approach for Common-Mode Voltage Suppression

In this paper, a new modified model predictive control is proposed to improve the performance of the model predictive control for two-level voltage source inverters by alleviating computational burden and the disadvantages associated with the conventional model predictive control strategy. The objective of the proposed method is to reduce the number of candidate voltage vectors in each sector, thereby improving the overall performance of the control system, as well as achieving common-mode voltage reduction for two-level voltage source inverters. Two strategies are introduced to achieve this objective. Firstly, an algorithm is developed based on statistical computational processes to pre-define the candidate voltage vectors. This strategy involves ranking and considering the most frequently used voltage vectors. Consequently, by reducing the computational burden, the search space for the optimal voltage vectors is reduced. Furthermore, based on statistical results, a strategy is proposed to divide the sectors into three sectors instead of the six sectors in the conventional method. This approach effectively reduces the number of candidate voltage vectors. The modified model predictive control strategy aims to improve the efficiency of the control system by reducing the computational burden, and suppressing the common-mode voltage. The simulation and experiments are carried out to verify the effectiveness of the proposed strategy under various operational conditions. The results demonstrate that the modified model predictive control approach significantly reduces the computational burden and complexity of the control system while effectively suppressing the common-mode voltage; this contributes to improving the performance of two-level voltage source inverters and enhancing their applicability for connecting the renewable energies to the grid.

МОДЕЛИРОВАНИЕ СИСТЕМЫ «СИНХРОННЫЙ ГЕНЕРАТОР – ПРЕОБРАЗОВАТЕЛЬ ЧАСТОТЫ – СИНХРОННЫЙ ДВИГАТЕЛЬ»

The relevance of the use of AC-AC power transmission systems on vehicles, including autonomous locomotives, using synchronous generators and traction synchronous motors is showed. Typical block diagram of electric transmission of traction rolling stock and functional diagram of electric power transmission with synchronous generator and traction motors are given. Based on the theory of a generalized electrical motor, a mathematical description has been devel-oped in a two-phase coordinate system for a synchronous generator with excitation winding and starting winding and a synchronous motor with permanent magnets, its equivalent schemes are shown. The results of simulation in Matlab Simulink of electric system with two traction motors connected to frequency converters with two-level voltage source inverters are given. Direct torque control system with a table function of switching the voltage source inverter by output signals of relay regulators of torque and flux linkage is used for motor control. Based on the obtained re-sults, recommendations for the synthesis of energy-efficient control systems for synchronous motors with permanent magnets are given

Comparison of 2L + 2M and 6L SVPWM for Five-Phase Inverter to Reduce Common Mode Voltage

Multiphase drives have received a lot of interest because of their several features over traditional three-phase systems for high-power applications. Pulse-width modulation (PWM) approaches are necessary to regulate the supply for multiphase ac drives. As a result, it is vital to continually improve the modulation and control approaches used to upgrade output power converters’ quality. This paper offers a comparative analysis of the 2L + 2M and 6L space vector pulse-width modulation (SVPWM) techniques applied to a five-phase two-level voltage source inverter (VSI) fed an inductive (R-L) load. The comparative evaluation is based on measuring the inverter switching losses, the total harmonic distortion (THD) values, and the common mode voltage (CMV) under different operation scenarios. A system model is carried out by MATLAB/Simulink. An experimental prototype is constructed in the lab to validate the theoretical analysis. Simulation results for the system based on the two SVPWM techniques are obtained at different modulation indices and different output frequencies and are confirmed by the experimental results. It has been found that the peak-to-peak CMV of the 6L method is 80% lower than that of the 2L + 2M method. Moreover, 6L SVPWM offers better DC-link utilization compared to 2L + 2M SVPWM.

Gamma Modulation Based Three-Phase Two-Level Voltage Source Inverter For Reduced Switching Losses With Dynamic Load Changes

Gamma Modulation Based Three-Phase Two-Level Voltage Source Inverter For Reduced Switching Losses With Dynamic Load Changes

Robust integral backstepping control microgrid connected photovoltaic System with battery energy storage through multi-functional voltage source inverter using direct power control SVM strategies

This paper proposes a robust control based on the integral backstepping control (IBC) for power quality enhancement of micro-grid-connected photovoltaic (PV) system with battery energy storage systems (BESS), The DC side consists of a PV system and battery storage. As for the AC side, it consists of three phases of a multi-functional two-level voltage source inverter (MVSI) coupled to the electrical grid via an inductive filter, all feeding a non-linear load. The MVSI is controlled by a nonlinear direct power control (DPC) strategy with space vector modulation (SVM) and the proposed IBC technique. Using the proposed IBC technique to control the voltage of the DC link voltage loop, the active/reactive power loops of the grid, the compensation of the harmonic currents of the network, and the injection of the power of the PV battery into the grid, loop of the maximum power point tracking (MPPT) regardless of the random nature of weather changes and guarantees optimal power management system battery storage. Using simulation under the MATLAB environment, the proposed control system was validated and compared to the conventional strategies (proportional–integral controller and backstepping controller) in terms of success, performance, robustness, and efficiency. In addition to its ability to respond under any irradiation distortion and non-linear load unbalance.

Performance improvements of power converters for high power induction motor drive

This paper deals with a reliable transformer configuration with simple wiring and less number windings for twenty-four pulse AC-DC converter, which is used in medium voltage drive system so that it can adverse the effects produced by harmonics currents fed into the grid by converters that do not affect other consumers connected to the same electrical grid. Apart from this, a five-level symmetrical multilevel inverter configuration is used by cascading four two-level voltage source inverters. It is designed with less quantity of components counts like; power switches, diodes and electrolytic capacitors. Because power quality impacts the suitability of electrical power for consumer electronics, an attempt is made in this work to improve power quality through the connecting high-pulse converter at the grid end instead of 12-pulse and modified level-shifted pulse width modulation for a multi-level inverter at the drive end. Performance of the described topology is verified in the laboratory using a drive-through MATLAB/Simulink environment and a prototype at a reduced scale. The feasibility and effectiveness of the proposed topology are demonstrated by a comprehensive comparison with recently reported schemes. Promising results validate this new concept.

A Novel Double-Voltage-Vector Model-Free Predictive Current Control Method for Two-Level Voltage Source Inverters

An improved model-free predictive current control (MFPCC) scheme based on double-voltage-vector for two-level voltage source inverters (2L-VSIs) is proposed in this paper. First, two basic voltage vectors are chosen in each control period, whose durations are calculated based on the cost function. Then, a novel current gradient updating method is developed by using the applied two voltage vectors to calculate the current gradients of the remaining six voltage vectors. As a result, the stagnation effect can be eliminated and current ripples and total harmonic distortion can be reduced effectively. In addition, due to the nature of vector diagram symmetry, the processing of current gradient updating is simplified and the calculation speed is increased. The effectiveness of the proposed scheme is verified by simulation and experimental results from the 2L-VSI system.

Fractional-Order Model-Free Predictive Control for Voltage Source Inverters

Currently, a two-level voltage source inverter (2L-VSI) is regarded as the cornerstone of modern industrial applications. However, the control of VSIs is a challenging task due to their nonlinear and time-varying nature. This paper proposes employing the fractional-order controller (FOC) to improve the performance of model-free predictive control (MFPC) of the 2L-VSI voltage control in uninterruptible power supply (UPS) applications. In the conventional MFPC based on the ultra-local model (ULM), the unknown variable that includes all the system disturbances is estimated using algebraic identification, which is insufficient to improve the prediction accuracy in the predictive control. The proposed FO-MFPC uses fractional-order proportional-integral control (FOPI) to estimate the unknown function associated with the MFPC. To get the best performance from the FOPI, its parameters are optimally designed using the grey wolf optimization (GWO) approach. The number of iterations of the GWO is 100, while the grey wolf’s number is 20. The proposed GWO algorithm achieves a small fitness function value of approximately 0.156. In addition, the GWO algorithm nearly finds the optimal parameters after 80 iterations for the defined objective function. The performance of the proposed FO-MFPC controller is compared to that of conventional MFPC for the three loading cases and conditions. Using MATLAB simulations, the simulation results indicated the superiority of the proposed FO-MFPC controller over the conventional MFPC in steady state and transient responses. Moreover, the total harmonic distortion (THD) of the output voltage at different sampling times proves the excellent quality of the output voltage with the proposed FO-MFPC controller over the conventional MFPC controller. The results confirm the robustness of the two control systems against parameter mismatches. Additionally, using the TMS320F28379D kit, the experimental verification of the proposed FO-MFPC control strategy is implemented for 2L-VSI on the basis of the Hardware-in-the-Loop (HIL) simulator, demonstrating the applicability and effective performance of our proposed control strategy under realistic circumstances.

A Review on Multilevel Converters for Efficient Integration of Battery Systems in Stationary Applications

Recently, multilevel converters (MLCs) have gained significant attention for stationary applications, including static compensators, industrial drives, and utility-grid interfaces for renewable energy sources. Compared to two-level voltage-source inverters (VSI) MLCs feature high-quality AC voltage with reduced harmonic content despite the lower switching frequency of the semiconductor devices. On the DC side, MLCs can integrate multiple isolated/non-isolated battery modules instead of a single battery pack. This helps to keep the system in service in case of a malfunction of one or more battery modules, as well as active balancing among the modules, a feature not possible with two-level VSI. In general, MLCs can be classified into two types: (i) two-port MLCs, which provide a single interface to connect with the battery pack, and (ii) multiport MLCs, which provide multiple interfaces to allow connection at the module or cell level. The classical topologies of both MLC types (e.g., neutral point clamped, flying capacitor, cascaded bridge) face limitations due to the high switch count. Consequently, many hybrid and reduced-switch topologies are reported in the literature. This paper presents a critical overview of both classical and recently reported MLC topologies and offers a better insight of MLC operation for grid-connected and standalone applications. In addition, the analysis thoroughly assesses various high-level control and modulation strategies while considering active balancing among the battery modules. Other salient features such as balancing speed during offtake/grid-injection mode and fault-ride-through capability are also incorporated. In conclusion, the key findings are summarized for a better understanding of the present and future integration of battery systems in stationary applications.

A Low-Complexity Modulated Model Predictive Torque and Flux Control Strategy for PMSM Drives Without Weighting Factor

This article proposes a modulated model predictive torque and flux control (M2PTFC) method with low complexity for a two-level voltage source inverter (2L-VSI)-fed permanent magnet synchronous motor (PMSM). The proposed strategy aims to reduce the computation burden and simplify the control implementation of the conventional M2PTFC scheme by reducing the number of candidate voltage vectors at every control sample to the minimum (i.e., only two candidates) and eliminating the weighting factor of the cost function and its corresponding tuning procedures. For these purposes, the proposed method devotes different control objectives to the duty modulation and the cost function evaluation processes while executing them sequentially. First, aiming at torque ripple reduction, a duty modulation strategy is proposed based on the analysis of torque deviations produced by different voltage vectors, which ensures proper selection of the two candidates and restricts active voltage vectors (AVVs) that cause high deviations. Then, these candidates are evaluated based on a cost function assigned to achieve the stator flux control objective. The effectiveness of the proposed control scheme is verified through comparative assessment with the conventional M2PTFC and two existing simplified methods by means of simulation and experimental results.

Open-Phase Fault-Tolerant DTC Technique for Three-Level NPC VSI-Fed Five-Phase Induction Motor Drives

The demand for motor drives based on multiphase machines (MMs) is increasing due to their inherent fault-tolerant capabilities. To achieve satisfactory post-fault operation, a proper fault-tolerant controller is needed. Some direct-torque-control (DTC) techniques have been reported for five-phase induction motor (FPIM) drives under an open-phase fault (OPF). DTC offers simplicity, fast response, and less parameter sensitivity. However, the existing fault-tolerant DTC methods were designed for two-level voltage-source inverters (VSIs). A three-level neutral-point-clamped (NPC) VSI allows greater flexibility in the switching states, lower current and torque ripple, and reduced common-mode voltage (CMV). However, the increased number of switching states requires the design of new DTC methods, able to tolerate OPFs while providing satisfactory performance in various aspects. In this article, two fault-tolerant DTC techniques are developed for three-level NPC VSI-fed FPIM drives under an OPF. The possible switching states are synthesized with suitable virtual vectors (VVs), addressing the dc-link voltage balance, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\text {d}v/\text {d}t}$ </tex-math></inline-formula> , CMV, and dc-link utilization. The two methods are compared under an OPF in these terms, as well as regarding the average switching frequency. Comparative experimental results are provided to assess the viability of the developed DTC schemes at steady-state and dynamic conditions.

Theoretical and Experimental Comparative Analysis of Finite Control Set Model Predictive Control Strategies

This research paper studies and highlights the features of the most popular finite control set model predictive control (FCS-MPC) strategies available in the state of the art, which are the optimal switching vector (OSV-MPC), modulated model predictive control (M2PC), and optimal switching sequence (OSS-MPC) methods. Thus, these strategies are studied experimentally by analyzing the transient and steady state performance using a grid tie conventional three-phase two-level voltage source inverter (VSI) with inductive output filter in a Typhoon HIL real-time simulator (RTS) with a Texas Instruments F28379D digital signal processor (DSP). Hence, quantitative indicators, such as the maximum tracking error, the mean absolute error, the settling time, the total harmonic distortion, the switching frequency spectrum, the switching pattern, and the computational burden are compared with the aim to deduce the best strategy for each criteria.

A study on performance parameters of three-level T-type inverter based PMSM drives for electric vehicles applications

In this paper, a comparative analysis is obtained to analyse the performances of two-level conventional and three-level diode clamped voltage source inverter-based drives. Carrier-based space vector modulation technique is employed in both three-level & two-level voltage source inverter (2L-VSI)-based drives. Comparative study for 2L-VSI, three-level neutral-point-clamped (3L-NPC) and three-level T-type neutral-point-clamped (3L-TNPC) inverters are performed in view of conduction & switching losses and harmonic profile. Also presented in this work, the dynamic response of field-oriented controlled (FOC) permanent magnet synchronous motor (PMSM) drive under varying load conditions towards EV applications. Rapid changes in speed and loading in Electric Vehicle (EV) traction drives lead to sharp fluctuations in modulation depth and power factor (PF). With variation of modulation index and power factor, power losses of all the three inverters are analysed. Also, in the present work, control logics are simulated in MATLAB to observe various speed-torque combinations of 5.4 kW PMSM drive. Additionally, power losses of inverters are developed in PLECS environment. By using a scaled-down prototype of 5 hp PMSM drive, the results are carried out for hardware validation.

Comparison of SVPWM Techniques Under Switching Loss Control for Induction Motor Drive With LC Filters

Only precise industrial applications can benefit from the high-frequency performance of variable-speed drives with low switching losses. A five-phase induction motor (FPIM) is connected to a voltage source inverter (VSI) via a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$LC$</tex-math></inline-formula> filter (low pass filter) to reduce high-frequency losses in the motor. A five-phase sinusoidal voltage is used to lower the high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dv/dt$</tex-math></inline-formula> at the motor terminals. However, sustained resonant frequency oscillations destabilize closed-loop control of the FPIM drive at certain operational points. This paper presents and analyzes a variety of high-frequency SVPWM techniques, both continuous and discontinuous. It is also possible to optimize the switching frequency of the five-phase two-level VSI fed FPIM drive using an improved current ripple prediction method. Auxiliary circuits and high-frequency sensors are not necessary in this system, making it more stable. Simulated and experimental results are used to evaluate the stability of a drive under a variety of conditions.