Search Results (82)

The increasing penetration of renewable technologies, particularly photovoltaic (PV) and fuel cell (FC) systems, into microgrid networks has created new challenges in maintaining voltage stability, harmonic performance, and overall power quality. This study presents a comparative evaluation of two modulation and control strategies, which are a Simple Boost Control (SBC) and Space Vector Modulation (SVM). The system is modeled and simulated under standard test conditions (STC) as well as dynamic fluctuations in irradiance to evaluate the inverter performance, total harmonic distortion (THD), and DC-link voltage stability. Simulation findings indicate that although SBC provides structural simplicity and dependable voltage enhancement, the SVM approach delivers greater harmonic mitigation, more seamless inverter performance, and improved voltage utilisation in variable conditions. The results enhance the optimisation of power electronic control systems for renewable energy microgrids, facilitating steady and efficient operation in accordance with South Africa’s green energy goals. Full article

Direct power control (DPC) is widely recognized for its simplicity and fast dynamic response; however, conventional implementations based on hysteresis comparators suffer from critical limitations, including variable switching frequency and pronounced active power oscillations, which hinder their applicability in renewable and hybrid energy systems. To address these challenges, this study proposes a fractional-order predictive DPC strategy incorporating a fractional-order proportional–integral (FOPI) regulator to enhance dynamic performance and robustness. The proposed method is systematically evaluated against both a conventional proportional–integral-based DPC (PI-DPC) and existing fractional-order DPC approaches under identical operating conditions using MATLAB simulations. The results demonstrate that the proposed controller achieves a stabilized switching frequency while significantly improving DC-link voltage performance. Specifically, the proposed method reduces voltage ripples to 0.027 V compared to 0.094 V and 0.104 V for PI-DPC and FOPI-FOPI-DPC with space vector modulation (SVM), corresponding to improvements of 71.27% and 74.03%, respectively. The overshoot is also reduced to 0.75%, outperforming PI-DPC (1.25%) and FOPI-FOPI-DPC-SVM (1%), with improvements of 40% and 25%. In terms of dynamic response, the proposed approach achieves a fast response time of 0.06 s, representing a 40% improvement over PI-DPC, while maintaining comparable performance with other fractional-order methods. Additionally, the steady-state error is reduced to 0.04 V, achieving improvements of 60% and 50% compared to PI-DPC and FOPI-FOPI-DPC-SVM, respectively. Although the settling time shows marginal variation, the overall system exhibits enhanced stability and robustness. These outcomes highlight the effectiveness of integrating fractional-order control with predictive strategies, offering a robust and practically viable solution for real-world hybrid power systems that integrate renewable generation and energy storage. Full article

Common-mode voltage (CMV) is a critical concern in motor drive applications employing multilevel inverters, as it can lead to significant issues such as high-frequency noise, electromagnetic interference, and motor bearing degradation. These effects can compromise the reliability, reduce the operational lifespan of electric machines, and introduce safety hazards. In this study, an enhanced Direct Torque Control (DTC) strategy incorporating Space Vector Modulation (SVM) is proposed to specifically address CMV-related challenges in induction motors (IM) driven by a three-level Neutral-Point-Clamped (NPC) inverter. The proposed DTC scheme utilizes a specialized modulation technique that effectively mitigates CMV while also minimizing current harmonic content, and torque and flux ripples with a constant switching frequency. The developed SVM algorithm simplifies the three-level space vector representation into six equivalent two-level diagrams, enabling more efficient control. The zero-voltage vector is synthesized virtually by combining two active vectors within a two-level hexagonal structure. The effectiveness of the proposed DTC approach is validated through both simulation and Hardware-In-the-Loop (HIL) testing. Compared to the conventional DTC method, the proposed solution demonstrates superior performance in CMV minimization and leakage current reduction. Notably, it limits the CMV amplitude to V_dc/6, a significant improvement over the V_dc/2 typically observed with the standard DTC approach. Full article

The integration of renewable energy sources, including photovoltaic (PV) and fuel cell (FC) systems, into AC grids has attracted immense research interest in recent times. Furthermore, incorporating these renewable sources of energy into medium-voltage grids is garnering increased attention because of the obvious benefits of medium-voltage integration at elevated power levels. Photovoltaic applications entail the arrangement of solar panels capable of outputting voltages up to 1.5 kV; nonetheless, fuel cells display restricted output voltage, with a maximum market range of 400 to 700 V. Hence, the efficient integration of renewable energy sources into low-voltage or medium-voltage grids demands the utilization of a step-up direct current (DC–DC) inverter and a converter for connection to the alternating current (AC) grid, in which an efficient step-up converter is critical for the medium-voltage grid. Therefore, this study presents a three-phase buck-boost split-source inverter (BSSI) that resolves the constrained output voltage of the fuel cells. This study focuses on modifying the configuration of a conventional three-phase split-source inverter (SSI) circuit by adding a few components while maintaining the inverter’s modulation. This novel circuit design enables the reduction in voltage strains on the inverter switch components and improves DC-link use in relation to a traditional SSI configuration. For an 800 bus, maximal voltage stress on the primary inverter switches is lowered when compared with the standard SSI that delivers entire DC-bus voltage to switches. A rectifier-based model is employed to simulate the behavior of a renewable energy source. Combining these advantages with the conventional modulation of the inverter offers a more effective design. The buck-boost split-source inverter (BSSI) was analyzed using three distinct modulation techniques: the sinusoidal pulse-width modulation scheme (SPWM), the third-harmonic injected pulse-width modulation (THPWM) scheme, and space vector modulation (SVM). The proposed analysis was validated through MATLAB-SIMULINK and practical outcomes on a 5.0 kW model. The practical and SIMULINK data were found to be closely aligned with the analysis. The circuit developed in this study also ensures efficient DC-to-AC conversion, specifically with regard to low-voltage sources, like fuel cells or photovoltaic (PV) systems. Full article

Many methods have been developed for multilevel Space Vector Modulation (SVM), but despite their inherent advantages, all of them have been more complex than the alternative option of using Pulse Width Modulation (PWM) with sinusoidal or modified references. Different axes like g-h at 60° or ja-jb-jc at 120° have been used to simplify the operations to find the three nearest vectors and their duty cycles, but the control signals of multilevel converters are the duty cycles of phases, not the duty cycles of vectors. Moreover, throughout this paper, it was found that local information is not sufficient to compute the duty cycles of the phases: global information should be taken into account to obtain full control on the common mode voltage (CMV), and the selection of the starting vector in the switching sequence is also critical to obtain a balanced CMV. The natural coordinates ab-bc-ca were used in this paper, and a straightforward method is proposed for multilevel SVM: a method that is comparable in complexity to multilevel PWM with modified references and leads to exactly the same control signals. This method can be used as an easy starting point to develop other SVM techniques for multilevel converters. Full article

To overcome the limitations of existing automatic modulation classification (AMC) methods that mainly target single-signal scenarios in radio-over-fiber (RoF) system, a mixed-signal AMC scheme based on phase noise-insensitive high-order cumulants (PNI-HOC) and distribution characteristics is proposed. The approach enables accurate classification of mixed signals in RoF system. Specifically, a PNI-HOC algorithm is first introduced to mitigate the influence of laser linewidth-induced phase noise. Then, distribution characteristics derived from the signal amplitude histogram are extracted to construct a two-dimensional characteristics space. These characteristics are subsequently fed into decision tree and support vector machine (SVM) classifiers for signal identification. To validate the effectiveness of the scheme, a 10 GBaud RoF system with a 70 km fiber link is implemented. The simulation results show that, compared with the conventional high-order cumulant method, the approach solely based on amplitude histogram distribution characteristics and the scheme based on deep neural networks (DNN) classifier using histogram characteristics, the proposed scheme achieves significantly higher classification accuracy at low optical signal–noise ratios (OSNRs). In particular, when the fiber length is 70 km and the OSNR is ≥16 dB, the classification accuracy of mixed signals is consistently maintained at 100%. Furthermore, the robustness of the proposed method is verified under various system impairments, including laser phase noise, chromatic dispersion and nonlinear effects, amplified spontaneous emission noise, multipath fading, etc., confirming its superior and stable performance. Full article

This paper presents a high-performance sensorless control strategy for induction motors using an Adaptive Neuro-Fuzzy Inference System (ANFIS) for rotor speed estimation, eliminating the need for mechanical sensors. The ANFIS approach leverages stator voltages and currents, reducing costs and complexity. The motor is controlled via Indirect Stator Field Orientation Control (ISFOC) with a three-level Neutral–Point–Clamped (NPC) inverter employing Space Vector Modulation (SVM). Symmetry in the motor’s magnetic structure and SVM’s switching patterns enhances control precision, stability, and efficiency while minimizing harmonic distortion. Simulation results validate the proposed ANFIS-based estimator’s superior performance compared to a MRAS-based Luenberger observer under various operating conditions, demonstrating accurate speed tracking and robustness against load disturbances. Full article

Multilevel inverters (MLIs) have become fundamental in contemporary power electronics, providing enhanced performance compared to conventional two-level inverters regarding their output voltage quality, efficiency, and scalability. This study comprehensively assesses multilevel inverter technologies, including their topologies, control systems, and various applications. The study starts with a comprehensive examination of the core concepts of MLIs, subsequently embarking on a detailed evaluation of both conventional and innovative topologies, such as diode-clamped, flying capacitor, cascaded H-bridge, and modular multilevel converters. The study further examines the control systems used in MLIs, including Pulse Width Modulation (PWM), space vector modulation (SVM), and Model Predictive Control (MPC), emphasizing their benefits and drawbacks. The applications of MLIs in renewable energy systems, electric cars, industrial drives, and grid integration are comprehensively examined. The study closes by examining growing trends, difficulties, and future research paths, emphasizing the ability of MLIs to transform power conversion systems. Full article

This paper introduces a novel field-oriented control (FOC) strategy for an open-end stator three-phase winding induction motor (OEW-TP-IM) using dual space vector modulation-pulse width modulation (SVM-PWM) inverters. This configuration reduces common mode voltage at the motor’s terminals, enhancing efficiency and reliability. The study presents a backstepping control approach combined with a mean value theorem (MVT)-based observer to improve control accuracy and stability. Stability analysis of the backstepping controller for key control loops, including flux, speed, and currents, is conducted, achieving asymptotic stability as confirmed through Lyapunov’s methods. An advanced observer using sector nonlinearity (SNL) and time-varying parameters from convex theory is developed to manage state observer error dynamics effectively. Stability conditions, defined as linear matrix inequalities (LMIs), are solved using MATLAB R2016b to optimize the observer’s estimator gains. This approach simplifies system complexity by measuring only two line currents, enhancing responsiveness. Comprehensive simulations validate the system’s performance under various conditions, confirming its robustness and effectiveness. This strategy improves the operational dynamics of OEW-TP-IM machine and offers potential for broad industrial applications requiring precise and reliable motor control. Full article

This paper presents a Space Vector Modulation (SVM) method with a novel zero vector distribution system for electrical vehicle drives with a six-phase induction motor working under the Direct Field-Oriented Control (DFOC) method. Different SVM methods are described and compared, and a new approach with long vectors only and a special zero vector distribution, that compensates for the third harmonic component is proposed. The DFOC method is described and the influence of the applied modulation method on six-phase motor currents is shown. Results of our experimental studies on the DFOC method are presented and discussed. The proposed modulation method for a six-phase Voltage Source Inverter can be applied in fault-tolerant electrical vehicles. Full article

This paper provides an overview of existing theories on various modulation strategies for current-source inverters (CSI), particularly focusing on space vector modulation (SVM). The emphasis is on the development of detailed simulation models that improve understanding and allow practical application. Three important modulators are analyzed: voltage-source inverter (VSI)-derived CSI SVM modulator, direct CSI SVM modulator, and direct duty ratio CSI PWM modulator (DDPWM). These models are important for researchers and practicing engineers as they allow simulation, modification and better understanding of CSIs. This paper begins with a theoretical overview of the functionality of CSIs and presents the modulation techniques needed to develop simulation models. These modulation techniques use modular components to create complete simulation models. Application examples are provided to use the correct/valid parameters such that the operation/waveforms can be compared with the theory. Integrating established mathematical models with effective simulation tools enhances the understanding and application of CSI modulators. This method not only makes it easier to employ these CSIs instead of conventional inverter systems, but it also increases the possibility of power electronics advancements by creating better and more reliable systems. Full article

This paper proposes an improved Maximum Torque Per Ampere (MTPA) control method based on The Direct Torque Control-Space Vector Modulation (DTC-SVM) control algorithm using d-axis flux optimization. The proposed algorithm simplifies the existing DTC-SVM control method by geometrically interpreting its complex equations thereby providing a more straightforward and efficient approach. The proposed algorithm geometrically computes the d-axis flux reference and compensation values for the MTPA control by continuously monitoring the q-axis flux in real time. Additionally, the compensation value of the d-axis flux reference is employed to compute the magnitude and phase reference values of the DTC-SVM voltage vector, which in turn generates the stator current values that align with the MTPA curve. The effectiveness of the proposed algorithm was validated through simulation results in MATLAB Simulink. When the proposed algorithm was applied, the torque response to the torque command improved compared to the DTC-SVM control. Additionally, for the same torque production, the stator current consumption of the IPMSM was reduced by approximately 12.55%, demonstrating improved efficiency. To further validate the effectiveness of the proposed algorithm, a dynamometer test system was established, and the IPMSM was tested across various speed ranges below the base speed while generating different torque outputs. The torque response dynamics and stator current consumption of the proposed algorithm were then compared with those of the DTC-SVM algorithm, confirming its enhanced performance. Full article

With the continuous proliferation and development of renewable energy technologies, three-level converters have gained widespread application due to their lower output harmonics and higher output voltage. However, in practical applications, multilevel converters inevitably encounter issues such as common-mode voltage (CMV) and neutral-point voltage (NPV) imbalance, which significantly affect system stability and operational lifespan. This paper investigates the root causes of neutral-point voltage fluctuations and common-mode voltage generation. It provides an analysis and summary of solutions for CMV suppression and NPV balancing, focusing on space vector modulation (SVM) strategies, carrier-based modulation techniques, modulation waveform approaches, and intelligent control methods. Furthermore, the paper explores future development trends, aiming to provide valuable insights for subsequent theoretical research and practical applications. Full article

A matrix converter (MC) converts an AC source voltage into a variable-voltage variable-frequency AC output voltage (direct AC-AC) without an intermediate DC-link capacitance. By eliminating the traditional DC-link capacitor, MCs can achieve higher power densities and reliability when compared to conventional AC-DC-AC converters. MCs also offer the following characteristics: total semiconductor solution, sinusoidal input and output currents, bidirectional power flow and controllable input power factor. This paper reviews the history, recent developments and commercialization of MCs and discusses several technical requirements and challenges, including bidirectional switches, wide bandgap (WBG) opportunities using GaN and SiC, overvoltage protection, electromagnetic interference (EMI) and ride-through in motor drive applications. MC design solutions and operation are discussed, including a comparison of control and modulation techniques as well as the detailed development of space vector modulation (SVM) to provide a deep insight into the control implementation and results. The paper concludes with compelling motor drive innovation opportunities made possible by advanced MCs including fully integrated and multiphase systems. For conventional MCs, size reductions of 30% are reported, as well as efficiencies of 98% and low input current total harmonic distortion of 3–5%. Full article

Electric vehicles demand efficient and robust motor control to maximize range and performance. This paper presents an innovative adaptive fractional-order sliding mode (FO-SM) control approach tailored for Direct Torque Control with Space Vector Modulation (DTC-SVM) applied to induction motor drives. This approach tackles the challenges of parameter variations inherent in real-world applications, such as temperature changes and load fluctuations. By leveraging the inherent robustness of FO-SM and the fast dynamic response of DTC-SVM, our proposed control strategy achieves superior performance, significantly reduced torque ripple, and improved efficiency. The adaptive nature of the control system allows for real-time adjustments based on system conditions, ensuring reliable operation even in the presence of uncertainties. This research presents a significant advancement in electric vehicle propulsion systems, offering a powerful and adaptable control solution for induction motor drives. Our findings demonstrate the potential of this innovative approach to enhance the robustness and performance of electric vehicles, paving the way for a more sustainable and efficient future of transportation. In fact, the paper proposes using an adaptive approach to control the electric vehicle’s speed based on the fractional calculus of sliding mode control. The adaptive algorithm converges to the actual values of all system parameters. Moreover, the obtained performance results are reached without precise system modeling. Full article