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A highly popular alternative in medium voltage and high-power applications is multilevel converters because of their superior performance over conventional two-level converters. The most commonly used control methods in the case of multilevel inverters are sine pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) methods. Among these two control strategies, SVPWM has superior performance over SPWM in terms of DC bus voltage utilization along with a reduction in total harmonic distortion (THD) of line voltages. The classical SVPWM method has various drawbacks such as computational complexity for identifying the location of reference voltage vector, sector identification, region identification, memory requirement to store lookup tables for switching vectors. The novel simplified SVPWM technique is presented for cascaded H-Bridge multilevel inverter (CHBMLI) in this paper. This simplified SVPWM method has overcome the drawbacks of the classical SVPWM method. This new technique has been implemented into a five-level CHBMLI to evaluate performance and also to compare with the SPWM method. The simulation has been performed in MATLAB software.

This paper provides theoretical and experimental discussions on the characteristics of the modular multilevel converter (MMC) when phase-shifted carrier sinusoidal pulse-width modulation (PSC-SPWM) is applied. Harmonic-cancellation characteristics of output voltage and circulating current are analyzed on the basis of a general implementation of PSC-SPWM with two freedom displacement angles. Five available PSC-SPWM schemes with different carrier displacement angles were obtained, and a detailed performance comparison about output voltage and circulating current harmonic characteristics is presented. On the basis of the equivalent circuit with ideal transformer representation of the SMs, capacitor voltages affected by PSC-SPWM schemes are also briefly analyzed. The proposed PSC-SPWM schemes can unify two different cases of odd and even SM situations for output voltage and circulating current harmonic minimization, respectively. Lastly, the optimal schemes for practical MMC application were verified by simulation and experiments on an MMC prototype.

In high power, medium voltage applications, Current Source Inverters CSIs are connected in parallel to accommodate high DC currents. Using a proper multilevel modulation technique, parallel-connected CSIs can operate as a Multilevel CSI (MCSI). The most common modulation technique for MCSIs is the Phase-Shifted Carrier SPWM (PSC-SPWM). The proper operation of the MCSI requires each CSI modules to have the same average current flowing through its sharing inductors. In practice, the average currents of the CSI modules deviate from their nominal values. Therefore, current balancing mechanisms must be implemented. In the literature, several solutions have been proposed to tackle the current imbalance problem. Most of these solutions are based on altering the phase-shift or magnitude of the carrier waveforms of the PSC-SPWM. They require dedicated PI controllers and they are applicable to MCSIs with specific numbers of levels. This paper proposes a Current Balancing Algorithm (CBA) that can be implemented in any MCSI with any number of levels. The proposed CBA does not require any PI controllers, nor does it require any alteration to the PWM carrier waveforms. The CBA is implemented using a modified Level-Shifted SPWM (LS-PWM). The modified LS-SPWM is shown to produce lower THD and lower di/dt when compared to the PSC-SPWM. The CBA and modified LS-SPWM where implemented in a proof-of-concept lab prototype. The experimental results are presented for the five-level and seven-level cases.

To achieve “high voltage, low current” in the induction heating power circuit, enhance the flexibility of component selection in the circuit, and improve the quality of the inverter’s output waveform, a new control strategy of a single-phase NPC three-level inverter with unipolar frequency-doubling SPWM method is proposed. With the series connection of IGBTs in a single-phase NPC three-level inverter, the voltage withstand requirement of IGBT is reduced by half. The middle four IGBTs are controlled using unipolar frequency-doubling SPWM, while the outer four IGBTs are turned on later and turned off earlier to address the neutral point voltage imbalance issue in the inverter. Simulation results show that, compared with the traditional bipolar SPWM-controlled single-phase full-bridge inverter, the DC-side input voltage of the inverter can be double, and the current flowing through the entire circuit can be halved under the same output power using the proposed method.

This study summarizes an analytical review on the comparison of three-phase static compensator (STATCOM) and active power filter (APF) inverter topologies and their control schemes using industrial standards and advanced high-power configurations. Transformerless and reduced switch count topologies are the leading technologies in power electronics that aim to reduce system cost and offer the additional benefits of small volumetric size, lightweight and compact structure, and high reliability. A detailed comparison of the topologies, control strategies and implementation structures of grid-connected high-power converters is presented. However, reducing the number of power semiconductor devices, sensors, and control circuits requires complex control strategies. This study focuses on different topological devices, namely, passive filters, shunt and hybrid filters, and STATCOMs, which are typically used for power quality improvement. Additionally, appropriate control schemes, such as sinusoidal pulse width modulation (SPWM) and space vector PWM techniques, are selected. According to recent developments in shunt APF/STATCOM inverters, simulation and experimental results prove the effectiveness of APF/STATCOM systems for harmonic mitigation based on the defined limit in IEEE-519.

This article presents an innovative asymmetric multilevel inverter (MLI) topology that outperforms conventional counterparts. The introduced topology presents a breakthrough in implementing power electronics control by maximizing specific levels while minimizing switching components. A cutting-edge control scheme for optimal operation of the cascaded half-bridge MLI is presented. The ant lion optimization (ALO) algorithm was implemented to optimize the switching control to reduce the total harmonic distortion (THD) and improve power quality. For verification, the performance and effectiveness of the ALO technique are assessed by comparing its results to those obtained using the simplified sinusoidal pulse width modulation (SSPWM) technique, genetic algorithm (GA), and particle swarm optimization (PSO) in existing literature. Simulation results verified the efficacy of ALO in finding the optimal parameters. The suggested method showcases a remarkable reduction in the THD compared to SSPWM. The quality of the resulting waveform was enhanced, and both filter size and cost were significantly reduced. To meet stringent IEEE standards, an LC filter has been designed with minimal size and proper requirements. Experimental results validation of the suggested scheme, using a dSPACE R&D controller board unequivocally, confirmed its robustness and effectiveness. This groundbreaking study not only introduces a superior asymmetric MLI topology but also validates its exceptional performance through comprehensive analysis and experimentation. The experimental waveforms showed good matching with the simulation outcomes. The findings hold immense promise for advancing the field of power system control and revolutionizing the designing and implementation of efficient and cost-effective inverter systems.

Multilevel inverters (MLI) consist of a wide range of power converters. They have many designs and have been introduced with different circuit topologies such as neutral point clamped, diode clamped, cascaded H-bridges, and flying capacitors. Some of these MLIs have disadvantages, including design complexity, size, and losses due to the large number of switching devices required when they produce many output voltage levels. They are also bulky in size and may require several DC power sources. This paper presents a review of the various topologies of single-phase T-Type MLIs (T-MLIs). These MLIs are used to convert DC power from renewable energy sources (RES)” into AC with a near-sine waveform and low total harmonic distortion (THD). Simple and complex MLI designs are discussed. The major types of modulation techniques are discussed, including sinusoidal pulse width modulation (SPWM), selective harmonic elimination (SHE), and preprogrammed PWM. Various methods of output voltage control are taken into consideration as well. The aim of this comprehensive survey is to identify T-MLIs for researchers and those interested in the power conversion field, as well as to discuss the many topologies, identifying designs with superior characteristics that can be efficiently implemented with RESs to obtain better AC voltage with enhanced power quality.

This paper aims to improve the energy autonomy and the mechanical performances of an on-board drive chain for robotics. The energy autonomy improvement is performed by reducing electrical losses in the inverter. Electrical losses are reduced by decreasing the number of switching cycles per period of the inverter’s power semiconductor switches, while maintaining a low Total Harmonic Distortion (THD). These improvements are expected thanks to a new control strategy called Pre-Calculated Pulse Width Modulation (PC PWM). The principle of this new control strategy is that all the symmetries of an ideal three-phase voltage system are assigned to the real output voltage of the inverter. Then the switching instants of the inverter’s switches are determined off line, by means of Fourier’s analysis, so that the maximum number of successive harmonics is zeroed. This allows the optimal switching sequence to be predefined, thereby reducing unnecessary commutations of the power switches. The performance of the new method (PC PWM) is evaluated through detailed simulation studies and compared with the conventional method called Sinusoidal Pulse Width Modulation (SPWM). The simulation results show that despite the reduction in the number of commutations per period, the performance of the actuation chain has been significantly improved with PC-PWM (new technique). Indeed, for the same mechanical load, the PC-PWM method allows for a lower current, a shorter transient response time and a lower torque ripple than the SPWM method.

The Multilevel inverter (MLI) plays a pivotal role in Renewable Energy (RE) systems by offering a cost-effective and highly efficient solution for converting DC from Photovoltaic (PV) sources into AC at high voltages. In addition, an innovative technology holds immense significance as it not only enables the seamless integration of PV systems into the grid but also ensures optimal power generation, thereby contributing to the widespread adoption of RE and fostering a sustainable future. This paper presents a modified sinusoidal pulse width modulation (SPWM) control scheme for a three-phase half-bridge cascaded MLI-powered PV sources. The selection of the MLI configuration is motivated by its reduced number of switching components, which enhances system reliability and simplifies experimental implementation. Compared to the SPWM schemes which require (m−1) carriers that make the generation of the pulse circuit very complex, the proposed control scheme requires only three signals: a carrier signal, a triangular waveform, and a modulating signal. This approach significantly reduces the complexity of control and facilitates practical implementation. The proposed control scheme simulation is verified using MATLAB/SIMULINK Software. The grey wolf optimization (GWO) algorithm is implemented to determine the optimal switching angles of the proposed control scheme. The Total Harmonic Distortion (THD) objective is selected to be the fitness function to be minimized for improving the quality of the output waveforms. For verification, the results of the proposed GWO-based modified SPWM control scheme are compared with those obtained using both the Particle swarm Optimization (PSO) and Genetic algorithm (GA) used in the literature. Simulation results declared that the proposed control scheme improves performance, especially THD which is minimized to 6.8%. Experimental validation has been conducted by building a laboratory prototype of the proposed system. The experimental and simulation results gave acceptable and limited convergent results considering the experimental difficulties.

The paper presents a comprehensive study on modeling a doubly fed induction generator (DFIG) and explores various control strategies for pulse-width modulation (PWM) in back-to-back (B2B) converter techniques. A DFIG is characterized by a wound rotor and three slip-ring induction machines, with the stator winding directly connected to the power grid and the wound rotor interfaced with the grid through a 3-phase AC/DC/AC converter. Typically, the converter connected to the grid is referred to as the grid side converter (GSC), while the converter attached to the rotor's slip-ring circuit is termed the rotor side converter (RSC). This research delineates various PWM-based B2B converter methodologies applied to the DFIG within wind energy turbines, aiming to regulate the RSC for optimal power capture. The study employs MATLAB/SIMULINK for constructing a multi-phase voltage source converter two-level (VSC-2L) model, leveraging different PWM techniques including Sine-PWM, Sinusoidal-PWM with third harmonic injection (THIPWM), and space vector PWM (SVPWM). These techniques are assessed based on total harmonic distortion (THD) using fast Fourier transform (FFT) analysis. The findings indicate that SVPWM offers several advantages, such as ease of digital implementation, lower THD, reduced switching frequency losses, and more efficient utilization of the DC link voltage, thereby enhancing control strategy effectiveness.