Three-phase Voltage Source Inverter Research Articles

Disturbance Observer Based Sensorless Predictive Control for High Performance PMBLDCM Drive Considering Iron Loss

The control of motor drive without considering iron loss affects the phase back electromotive force and the torque performance. This article investigates the performance of permanent magnet brushless direct current motor (PMBLDCM) modeling taking impact of iron loss into account. A disturbance observer based sensorless scheme is proposed for PMBLDCM model with precise estimation of the rotor angular position. The effect of unmodeled nonlinear parameters on iron loss of PMBLDCM are regarded as disturbances for the proposed sensorless approach. A linear feedback control law with optimal current vector formulation is introduced to minimize the current ripple and torque ripple resulting in reduced copper loss. In order to select optimum switching vector considering the effect of iron loss, a model predictive control technique is proposed for the three-phase three-level neutral point clamped voltage source inverter driven PMBLDCM. The proposed sensorless predictive control (SPC) algorithm is verified both by simulation and experiments. The SPC approach demonstrates improved performance compared to the conventional approach in which the effect of iron loss is not taken into account.

Machine-Learning-Based Diagnosis of an Inverter-Fed Induction Motor

The principal objective of this paper is to detect and automatically monitor switch open-circuit faults in a two-level three-phase voltage source inverter fed induction motor from the processing of its current signals. The proposed diagnostic method uses both signal processing techniques and machine learning techniques in order to detect and localize the switch under an open-circuit fault. First, the Hilbert-Huang transform using the empirical ensemble mode decomposition is employed for each phase current signal, which leads to extracting the intrinsic mode functions. In order to optimally choose the function indicating the open-circuit fault harmonic, two factors, namely, the root mean square and the correlation coefficient are calculated out for each function. In this regard, two criteria are proposed that lead to choose the optimal function giving better information about the defected phase. The spectral envelope of the optimal function permits extra0cting the fault harmonic of the switch. Second, different machine learning techniques are applied to locate and classify the switch open-circuit faults with the hyper-parameters optimization for a better design of the different models. Finally, a comparative study of the different machine learning techniques is carried out for determining the best classifier for the open-circuit faults. The experimental results effectively demonstrate a very high classification rate of 98.98%.

A Three-Phase Grid Connected Photovoltaic System with Modified MPPT Method

In this study, a three-phase grid-connected Photovoltaic system is demonstrated. A photovoltaic (PV) system that is connected to the grid, provides several benefits, including a topology that is simple, high efficiency and so on. Considering control scheme difficulty greatly enhanced because of all the regulatory requirements, which are maximum power point tracking (MPPT), coordinated with the supply voltage, harmonic drop as a current output, must be addressed at the same time. The DC/DC converter, solar panels, DC-link, three-phase voltage source inverter (VSI) on the grid, as well as output filters are all detailed representations of the essential components of the system in this model. Line current harmonic distortion should be reduced. A sophisticated control strategy with two PI controllers and MPPT is purposed in this paper to stabilize DC voltage. A robust phase- locked loop (PLL) synchronizes a grid-connected voltage source inverter with three phases. The simulation and practical findings reveal that the stability as well as efficiency of a three-phase grid connected PV system are high. Keywords- solar energy, grid-connected inverters, photovoltaic (PV), maximum power point tracking (MPPT).

DPWM Applying for Five-Level NPC VSI Powered by PV-Boost Converter Based on Takagi Sugeno Fuzzy Model

Power quality is interesting issue for power conversion PV system. Further there are challenges associated with extract of maximum power and minimize the part losses in commutation. In this paper, a three-phase five-level NPC voltage source inverter (VSI) using discontinuous pulse-width modulation (DPWM) and feeding by a PV/DC-DC boost converter based on a Takagi-Sugeno T-S fuzzy controller is presented. The photovoltaic energy system is described by nonlinear equations. A T-S fuzzy model is used to transform the nonlinear equations into a fuzzy model by modeling the irradiation, temperature and output voltage parameters. The control parameters have been computed based on Linear Matrix Inequalities tools (LMI) and the stability of the system is ensured by Lyapunov approach. In the second stage for power conversion (DC/AC), a discontinuous pulse-width modulation (DPWM) is used and approved; it offers the possibility of reducing switching losses and the THD harmonic rate. The simulation was performed in the MATLAB/Simulink software using an R-L load and the obtained results are confirmed the feasibility and reliability of the proposed method for the PV conversion system.

A Robust Iterative Learning Control Technique to Efficiently Mitigate Disturbances for Three-Phase Standalone Inverters

This article investigates a robust iterative learning control (ILC) technique that effectively rejects the influence of periodic and nonperiodic disturbances for a three-phase constant-voltage constant-frequency standalone voltage source inverter (VSI) with an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> filter under variable initial states. In conventional ILC, the learning dynamics are more complex when the initial iterative state is different at each iteration due to the fixed initial state value. Unlike conventional ILC, the proposed ILC follows a transformed dynamic model for robust learning rule convergence that is less restricted under varying initial states and significantly eliminates the impact of periodic and nonperiodic disturbances. Moreover, a simplified stability analysis is provided, and the conditions required for robust learning rule convergence are discussed. A comparative verification with the results of conventional ILC using a TI TMS320F28335 digital signal processor based prototype standalone VSI proves that the proposed ILC technique offers robust and effective steady-state performance, with benefits such as reduced steady-state errors and low total harmonic distortion under periodic disturbances. Finally, its improved robustness and fast transient-state performance are validated under nonperiodic disturbances due to the existence of tough load conditions, i.e., step-changes of linear, unbalanced, and nonlinear loads with significantly distorted model parameters.

Digital Implementation of Harmonic and Unbalanced Load Compensation for Voltage Source Inverter to Operate in Grid Forming Microgrid

Voltage source inverter (VSI) is a good candidate for grid forming microgrid because it provides constant amplitude, frequency, and sinusoidal shape voltage at point of common coupling (PCC). As the microgrid is separated from utility grid, voltage quality of the PCC is easily affected by the type of load. To ensure power quality in grid operation, a three-phase VSI providing automatic voltage compensation for unbalanced or nonlinear load is presented in this paper. To maintain voltage quality at a certain level, the Fast Fourier Transform (FFT) algorithm is embedded in a proportional-resonant (PR) controller to mitigate the total harmonic distortion (THD) at PCC. In the meantime, any change of voltage magnitude that is caused by the unbalanced load could be reduced as well. To further enhance the transient response with the change of load, a predictive current (PC) controller is integrated into the PR controller. All the control strategies are implemented by digital approach. The effectiveness of proposed controls is verified through experiments on a testbed of the three-phase stand-alone system.

MAXIMUM POWER COEFFICIENT CONTROL OF A MICRO GRID-CONNECTED WIND ENERGY SYSTEM

This paper proposed the integration of the wind energy system (WES) with the grid consists of a wind turbine, a permanent magnet synchronous generator (PMSG), a switch-mode rectifier (SMR) and a three-phase voltage source inverter (VSI). Optimal torque control (OTC) method is applied to the converter on the generator side for maximizing the power coefficient under the change in wind speeds. To synchronize the WES with the grid, another controller is applied to keep dc-bus voltage at constant value and to regulate active and reactive power transmitted into a grid. A system of WES connected into a grid is created and tested in the MATLAB/SIMULINK platform version 2019b. Comprehensive simulation results are used to analyze and verify the excellent performance of the suggested two- control strategy on the machine and grid side.

Design of super-twisting algorithm control and observer for three-phase inverter in standalone operation

This paper develops a new control algorithm of a distributed generation system in the standalone operation. Behaviour of three-phase voltage source inverter is investigated and the guidelines for tuning the control parameters are presented. Based on Super-Twisting algorithm, the proposed controller guarantees the load voltage performance under different types of loads. The proposed controller is established for an inner-loop current controller and an outer-loop voltage controller in a dual control scheme. The proposed scheme is very simple, thus tuning control parameters is easy and the computational burden of the controllers is low. In order to validate the load current of the proposed system feasibility, a reduced-order observer is adopted. The simulation results indicate a more reliable and efficient performance compared to the standard sliding control and the adaptive control.

Modeling and analysis of solar-powered electric vehicles

The emission of greenhouse gasses from transportation vehicles is one of the most alarming environmental threats and the emission of these gases is mounting at a distressing pace. Limited fossil fuel resources are also a threat to the automobile industry. This work aims to describe the solar-powered electric vehicle (SPEV) as the key to solving the downside of fuel and pollution. A battery is used in an electric vehicle (EV) which is charged from both external power supply and also from photovoltaic (PV) panels which absorb radiation from the sunlight and generate electrical power. A maximum power point tracker (MPPT) controller is employed to track the utmost power. A buck-Boost converter is utilized to amplify the DC voltage procured from the photovoltaic module and then the boosted output is transmitted to a three-phase voltage source inverter (VSI). VSI is used to transform the solar DC voltage to AC voltage and feeds the brushless direct current (BLDC) motor which controls vehicle applications.

Average-Value Modeling of Direct-Driven PMSG-Based Wind Energy Conversion Systems

Control design and stability analysis of direct-driven permanent magnet synchronous generator (PMSG)-based wind energy conversion systems (WECSs) typically involve extensive time-domain simulations and frequency-domain analyses. Those studies rely on accurate and computationally efficient models of WECSs. Detailed switching models can accurately describe the transients of power-electronic converters, but they suffer from low computational efficiency due to the repeated switching events. In this paper, a numerically efficient model is developed for a direct-driven PMSG-based WECS. Analytical and parametric average-value modeling techniques are applied to its switching subsystems, including a 12-pulse diode rectifier, a three-phase-interleaved boost converter, a dual three-phase voltage source inverter (VSI), and a crowbar circuit. The average-value models (AVMs) improve the simulation efficiency by representing the terminal characteristics of switching subsystems with a set of algebraic equations. In addition, numerical linearization techniques can be directly employed for them to obtain frequency-domain characteristics. The proposed model is verified against the detailed switching model and existing AVM in MATLAB/Simulink. It is shown to have excellent accuracy in both time-domain and frequency-domain studies while maintaining high computational efficiency.

Hybrid optimization approach for optimal switching loss reduction in three-phase VSI

ABSTRACT In power electronics, the alleviation of the converter losses is the major target to accomplish higher efficiency and lower thermal stress that can pave the way to lifetime enhancement of devices. Hence, this paper intends to implement a novel variable switching frequency system for switching loss minimisation in a 3-phase Voltage Source Inverter (VSI). Here, the count of commutations is minimised by varying the switching frequency over the fundamental period. Here, the switching loss is reduced by optimising the modulation index and the reference angle of VSI with a novel hybrid optimisation model. The proposed novel hybrid optimisation model is constructed by hybridising the concept of Group search Algorithm (GSO) and Rider Optimisation Algorithm (ROA) and hence referred to as Bypass updated Group search Algorithm (BU-GSO). Finally, the performance of BU-GSO is evaluated over the traditional models in terms of convergence analysis, Total Harmonic Distortion (THD) as well. Moreover, the evaluation is accomplished with inductive load variation and restive load variation, respectively.

Transformer-Less Cascaded Voltage Source Converter Based STATCOM

In this work, a transformer-less voltage source converter (VSC) based STATCOM is proposed with a combination of cascaded conventional three-phase voltage source inverters. This modular structure provides multilevel operation with reduced switch count and independent DC-link capacitors. The actual contribution of this paper is the transformer-less configuration of a conventional cascaded voltage source converter which provides reduced cost and volume as compared to other transformer-less converter configurations. The system provides reactive power compensation with better power quality when connected to the nonlinear power electronics load also. A simple control system is provided for balancing the Dc link capacitor voltage and reactive power compensation. The validation of the proposed model is analyzed with simulation using MATLAB/SIMULINK software and the results are obtained with different linear and nonlinear load configurations.

An Improved Finite Control Set Model Predictive Current Control for a Two-Phase Hybrid Stepper Motor Fed by a Three-Phase VSI

In this paper, an improved finite control set model predictive current control (FCS-MPCC) is proposed for a two-phase hybrid stepper motor fed by a three-phase voltage source inverter (VSI). The conventional FCS-MPCC selects an optimal voltage vector (VV) from six active and one null VVs by evaluating a simple cost function and then applies the optimal VV directly to the VSI. Though the implementation is simple, it features a large current ripple and total harmonic distortion (THD). The proposed improved FCS-MPCC builds an extended control set consisting of 37 VVs to replace the original control set with only seven VVs. The increase in the amount of VVs helps to regulate the current more accurately. In each control period, the improved FCS-MPCC takes advantage of deadbeat control to calculate a reference VV, and only the three VVs adjacent to the reference VV are predicted and evaluated, which decrease the computational workload significantly. Build waveform patterns for all VVs in the unbalanced circuit structure to modulate the optimal VV using discrete space vector modulation, which improves the current quality in reducing current ripple and THD. The comparative simulations and experimental results validate the effectiveness of the proposed method.

Trajectory tracking for a class of switched nonlinear systems: Application to PMSM

This paper proposes a state-dependent switching control for a class of switched nonlinear systems, whose model describes a permanent magnet synchronous machine (PMSM) fed by a three-phase voltage source inverter. Due to its high torque density, high efficiency and wide velocity range, this electrical drive is widely used for traction and several applications in robotics, aerospace, electric vehicles among others. The proposed design conditions are based on a non-quadratic Lyapunov function, dependent on the machine shaft displacement, and assure asymptotic tracking of a pre-specified time-varying rotational velocity profile with guaranteed performance. Properties of the nonlinear system under consideration are used to derive design conditions expressed in terms of linear matrix inequalities that can be solved efficiently. Special cases involving asymptotic stability toward step and ramp velocity profiles are presented. Experimental results are used to validate the proposed technique.

OPTIMAL SWITCHING LOSS REDUCTION IN THREE-PHASE VSI USING THRESHOLDED RIDER OPTIMIZATION ALGORITHM

This paper intends to develop a variable switching frequency system for switching loss minimization in a three-phase voltage source inverter. Switching losses are associated with the present value in switching instants, device voltage, and the number of commutations. Here, the number of commutations is minimized by varying the switching frequency over the fundamental period. The reduced switching loss is attained by optimizing the modulation index (MI) and reference angle. Thus, optimal switching patterns are generated with the optimized constraints, where the average value of switching losses over an entire period is determined, which has to be reduced. Accordingly, here, the optimization of MI and reference angle is carried out by thresholded rider optimization algorithm, which is the modification of the rider optimization algorithm. Finally, the experimental analysis is carried out for MI and a reference angle with respect to the switching loss parameter and total harmonic distortion.

Power quality improvement using dynamic voltage restorer (DVR)

This paper presents power quality issues, and ways to resolve these problems. There are a number of custom power devices which are used to resolve these issues. The Dynamic Voltage Restorer (DVR) is a special device that is used nowadays. To detect the voltage drop system, park transform is utilized and applied to the voltage regulator as a control system function, that detects the voltage amplitude at the sensitive load constantly in DVR (using a three-phase voltage source inverter with voltage loop control (PI)) (Martiningsih &amp; Prakoso, 2018). This paper is about basic working of DVR with simulation results. MATLAB is used in this work, and confirmed the convincingness of the DVR.

Optimized Fractional Order Based Droop Control with Improving the Flexibility of a Microgrid

This work presents an improved four-levels hierarchical control strategy for flexible microgrid based on three-phase voltage source inverters (VSIs) connected in parallel. In the proposed strategy, zero-level control is required to handle current and voltage control of VSIs. The primary-level that consists of a decentralized controller is based on a modified universal droop control by introducing a fractional-order derivative. It is used to enhance the power sharing quality during islanded mode and the desired power generation in grid-connected mode. In the secondary centralized control, the voltage and frequency deviations caused by the primary-control are restored. Also, this level includes the synchronization control loop that enables a seamless transition between both operation modes. In order to improve the flexibility of the microgrid, a sequential logic approach is proposed in the tertiary level. It is exploited to manage both the restoration and the synchronization loops at each transition, as well as the static switch (SS) which is used to connect/disconnect the microgrid to/from the main grid. The control parameters are optimized by using the self-learning particle swarm optimizer (SLPSO) algorithm. Simulations were performed to highlight the performances of the proposed hierarchical control approach compared with the well-known three-levels control scheme.

Evaluation and Minimization of Total Harmonic Distortion in Three-Phase Two-Level Voltage Source Inverter with Low Switching Frequency

Evaluation and Minimization of Total Harmonic Distortion in Three-Phase Two-Level Voltage Source Inverter with Low Switching Frequency

Constrained Modulated Model Predictive Control for a Three-Phase Three-Level Voltage Source Inverter

In the last decade, model predictive control (MPC) has been widely studied in power converters, such as voltage source inverters (VSIs). Unfortunately, MPC often presents a high computational burden that limits their applicability, especially when driving multilevel inverters (MLIs) because of their higher number of switching combinations than two-level inverters. As a result, some strategies have been developed to reduce the computational complexity of MPC. One of the most relevant is the use of artificial neural networks (ANNs) to approximate the behavior of an MPC. However, ANNs require to be evaluated at bounded inputs. Otherwise, their response cannot be guaranteed to be a good approximation of the controller they learned from. Furthermore, when driving an LC-filtered VSI, the inductor current can present high peaks due to the cross-coupling effect between the inductor and the capacitor. These current peaks can cause physical damages and loss of performance of an ANN-emulated MPC. This paper presents a new constrained modulated MPC (M <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> PC), better suited for ANN emulation, to overcome these issues. The proposed strategy evaluates the cost function once per switching region, allowing easy and intuitive constraint inclusion. Additionally, an overmodulation stage is used to handle negative duty cycles and enhance disturbance rejection. Finally, the proposal is validated through simulations, using MATLAB-Simulink, taking into account different load conditions. Simulations show that the constrained M <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> PC keeps the inductor current below its desired limit while having a good performance (low harmonic distortions and fast dynamics) even when the inverter operates near its boundaries.

Evaluation and minimisation of total harmonic distortion in three-phase two-level voltage source inverter with low switching frequency

Evaluation and minimisation of total harmonic distortion in three-phase two-level voltage source inverter with low switching frequency