Search Results (107)

In single DC-link current sensor-based phase current reconstruction for permanent magnet synchronous motor (PMSM) drives, the current reconstruction dead zone caused by insufficient active voltage vector duration restricted by driver dead time, switching settling, and Analog to Digital Converter (ADC) latency degrades current sensing accuracy, particularly in low modulation and sector boundary regions. Conventional phase shift methods, while extending the sampling window through Pulse Width Modulation (PWM) pattern modification, inevitably introduce asymmetric switching sequences that generate additional phase current harmonics and may reduce the linear modulation range. This article analytically characterizes the dead zone formation mechanism across the space vector plane and proposes a cross-cycle compensation strategy based on vector approximation. The method replaces the reference voltage vector with the nearest measurable vector in the present switching cycle and compensates for the resulting voltage error in the subsequent cycle, thereby extending the sampling window while preserving precise volt-second balance without extra hardware. Experimental results demonstrate that the proposed method eliminates the current reconstruction dead zone, achieves high-fidelity phase current reconstruction, and ensures robust dynamic performance under various load conditions and transients. The feasibility and effectiveness of the single current sensor drive are thoroughly validated. Full article

The cost and output voltage quality of multilevel inverters are among the most critical design considerations. Consequently, reducing the number of power switches and DC sources while improving output voltage quality plays a crucial role in achieving cost-effective designs. This paper proposes a new multilevel inverter topology capable of generating 17 voltage levels using a single DC source and only 12 power switches. A comprehensive comparison demonstrates the superior cost effectiveness of the proposed topology compared to existing counterparts. Moreover, modulation of reduced-switch multilevel inverters remains a challenge when conventional PWM techniques are employed, as they typically require complex logic circuits to generate appropriate switching patterns. To address this issue, this paper investigates the application of one-dimensional space vector modulation (OD-SVM) to control the proposed multilevel inverter without the need for any additional logic circuits. Simulation and experimental results validate the effectiveness of the proposed inverter topology and the OD-SVM control strategy. Full article

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

Z-source inverters (ZSIs) provide single-stage power conversion with inherent voltage boost capability through shoot-through (ST) states achieved using specialized PWM methods. This study compares various ST PWM strategies, Simple Boost PWM, Maximum Boost PWM, Constant Boost Third Harmonic Injection PWM, and Space Vector PWM, for high-voltage boost ZSI (HVB-ZSI) applications. A MATLAB/Simulink 2024a model was developed to assess their performance in terms of output-voltage quality, THD, capacitor-voltage stress, switch stress, and inductor–current ripple. Results indicate that while all techniques enable ST operation effectively, their voltage stress and harmonic performance differ notably, guiding optimal PWM selection for advanced ZSI-based systems. Full article

Induction motors (IMs) are widely used in variable-speed electric drive systems, where the motor is supplied by a voltage source inverter (VSI). Thus, PWM inverter–IM combination presents several issues that can degrade system performance, particularly overvoltage phenomena when long cables are used. In inverter-fed drive systems, the physical separation between the converter and the motor often requires long motor cables, which can significantly affect voltage stress. As the inverter’s output pulses propagate through the cable, voltage reflections and high-frequency oscillations occur at the motor terminals. We theoretically and experimentally investigate the effect of three PWM methods, namely Space Vector (SVPWM), Selective Harmonic Elimination PWM (SHEPWM), and Random PWM (RPWM) strategies, on overvoltage at the terminals of an induction motor fed by a PWM inverter through a long cable. The simulation results exhibit the validity and efficiency of SVPWM control to reduce overvoltage for different cable lengths. In addition, in order to reduce and eliminate all overvoltage peaks, three filters are proposed and evaluated: an RC filter, an RLC filter, and a compensator. The proposed PWM strategies are assessed using equivalent experimental results obtained on an induction motor fed by a two-level VSI. The experimental tests demonstrate also the efficiency of the SVPWM compared to other strategies. 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

Several industrial applications rely on induction motors to carry out processes essential for product manufacturing. Speed control of an induction motor commonly requires a pulse width modulated inverter capable of driving a system with long cables, suppression of common mode voltage, reduction in common mode current, and suppression of electromagnetic interference. This paper proposes a three-phase motor drive aimed at maintaining a constant common-mode voltage. The proposed system consists of two three-phase conventional full bridge inverters connected in parallel and having as an input two separate direct current sources. The proposed system is controlled by using the space vector pulse width modulation technique. By properly designing the switching signal sequences for both converters, the common-mode voltage can be maintained constant, thereby reducing the associated common-mode current to an RMS value of $92.3$ mA and enhancing the overall reliability of the system. The proposed system is validated through numerical simulations and by the implementation of an experimental prototype. Full article

Induction motors piloted by voltage source inverters constitute a major source of acoustic noise in industry. The discrete tonal bands generated by induction motor stator current spectra controlled by the fixed Pulse Width Modulation (PWM) technique have damaging effects on the electronic noise source. Nowadays, the investigation of new advanced control techniques for variable speed drives has developed a potential investigation field. Finite state model predictive control has recently become a very popular research focus for power electronic converter control. The flexibility of this control shows that the switching times are generated using all the information on the drive status. Predictive Torque Control (PTC), space vector PWM and random PWM are investigated in this paper in terms of acoustic noise emitted by an induction machine fed by a three-phase two-level inverter. A comparative study based on electrical and mechanical magnitudes, as well as harmonic analysis of the stator current, is presented and discussed. An experimental test bench is also developed to examine the effect of the proposed PTC and PWM techniques on the acoustic noise of an induction motor fed by a three-phase two-level voltage source converter. Full article

A three-phase inverter generates non-sinusoidal voltages, contains high order harmonics, and concentrates on switching frequency multiples. Supplying an induction machine (IM) with a voltage source inverter (VSI) increases the acoustic noise content which becomes unbearable, particularly for systems needing a moderate level of electric traction. The discrete tonal bands produced by the IM stator current spectrum controlled by the fixed pulse width modulation (PWM) technique have damaging effects on the electronic noise source. Moreover, it has been factually proven that the noise content is strongly associated with the harmonics of the source feeding electric machine. Thus, the harmonic content is influenced by the control strategy VSI to produce pulse width modulation (PWM). Currently, the investigation of new advanced control techniques for variable speed drives has developed into a potential investigation file. Two fundamental topologies for a three-phase inverter have been suggested in the literature, namely two- and three-level topologies. Therefore, this paper investigated the effect of variable and fixed PWM strategies, such as random PWM (RPWM) and space vector PWM (SVPWM), on the noise generated by an IM, powered with a two- or three-level inverter. Simulation results showed the validity and efficiency of the proposed variable RPWM strategy in reducing sideband harmonics for both the two and three levels at different switching frequencies and modulation indexes. The proposed PWM strategies were further evaluated by the results of equivalent experiments on an IM fed by a two-level VSI. The experimental measurements of harmonic current and noise spectra demonstrate that the acoustic noise is reduced and dispersed totally for the RPWM strategy. Full article

A PWM-based rotor position and speed estimator is presented in this study. The method is based on the measurement of the current response to conventional space vector pulse width-modulated voltage (SV-PWM) for PMSM drive applications. Model reference adaptive system (MRAS) estimators are often used for sensorless speed estimation. A MRAS typically uses two models: the reference model (voltage model) and the adaptive model (current model). The voltage model in flux-based MRAS uses the integration of stator voltages to calculate the stator flux. The pure integrator is usually replaced by a low-pass filter; however, this results in phase errors at low frequencies. The position is estimated using oversampling and averaging over a switching SV-PWM cycle, eliminating the need for integrators. Extensive experimental tests are presented to evaluate the performance of the PWM-based estimator. The results of the experiments demonstrate good performance at various speeds and under various load circumstances, in both motoring and regenerating modes. The proposed method also shows robustness to changes in motor parameters. Full article

The growing need for high-efficiency and reliable propulsion systems in naval applications, particularly within the evolving landscape of submarine warfare, has led to an increased interest in multiphase Permanent Magnet AC motors. This study presents a modelling and simulation approach for a 3MW, seventeen-phase Permanent Magnet AC motor designed for submarine propulsion, integrating an AI-based drive control system. Despite the advantages of multiphase motors, such as higher power density and enhanced fault tolerance, significant challenges remain in achieving precise torque and variable speed, especially for externally mounted motors operating under deep-sea conditions. Existing control strategies often struggle with the inherent nonlinearities, unmodelled dynamics, and extreme environmental variations (e.g., pressure, temperature affecting oil viscosity and motor parameters) characteristic of such demanding deep-sea applications, leading to suboptimal performance and compromised reliability. Addressing this gap, this research investigates advanced control methodologies to enhance the performance of such motors. A MATLAB/Simulink framework was developed to model the motor, whose drive system leverages an AI-optimised dual fuzzy-PID controller refined using the Harmony Search Algorithm. Additionally, a combination of Indirect Field-Oriented Control (IFOC) and Space Vector PWM strategies are implemented to optimise inverter switching sequences for precise output modulation. Simulation results demonstrate significant improvements in torque response and control accuracy, validating the efficacy of the proposed system. The results highlight the role of AI-based propulsion systems in revolutionising submarine manoeuvrability and energy efficiency. In particular, during a test case involving a speed transition from 75 RPM to 900 RPM, the proposed AI-based controller achieves a near-zero overshoot compared to an initial control scheme that exhibits 75.89% overshoot. 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 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 investigates the performance of a five-phase silicon carbide (SiC)-based current-source converter (CSC) integrated with a Doubly Fed Induction Generator (DFIG) for wind energy applications. The study explores both healthy and faulty operation, focusing on system behavior under transient conditions and various load scenarios in stand-alone mode. A novel five-phase space vector PWM strategy in dual coordinate planes is introduced, which enables stable control during normal and open-phase fault conditions. Experimental results demonstrate improved stator voltage and current quality, particularly in terms of reduced Total Harmonic Distortion (THD), compared to traditional voltage-source converter-based systems. Furthermore, the system maintains operational stability under a single-phase open fault, despite increased oscillations in stator quantities. The results highlight the potential of five-phase CSC-DFIG systems as a robust and efficient alternative for wind power plants, particularly in configurations involving long cable connections and requiring low generator losses. Future work will focus on enhancing fault-tolerant capabilities and expanding control strategies for improved performance under different operating conditions. Full article