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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.

Considering that the defects of traditional nearest–two–vector SVPWM (NTV–SVPWM) have a low voltage transfer ratio (VTR) and those of nearest–four–vector SVPWM (NFV–SVPWM) have a high output current harmonic, two improved space–voltage pulse–width–modulation (SVPWM) strategies are proposed in this paper, based on analyzing the harmonic characteristics of traditional NTV–SVPWM and NFV–SVPWM. The first strategy is to synthesize the referenced voltage vector according to the different weight factors by NTV–SVPWM and NFV–SVPWM. The second strategy is to synthesize the referenced voltage vector according to the different weight factors of NFV–SVPWM and the large vector. Compared to NTV–SVPWM, the simulation results show that the two proposed SVPWM strategies have lower output voltage errors and THDs. Compared to NFV–SVPWM, the simulation results show that the two proposed SVPWM strategies have higher VTRs and THDs. Compared to the two proposed SVPWM strategies, proposed SVPWM strategy one has a lower output voltage error and THD. The experimental results verify that the proposed modulation strategy is correct and feasible.

This paper proposes an Advanced Hybrid SVPWM (Space Vector Pulse Width Modulation) technique that integrates the benefits of RPS-PWM (Reference Point Saturation-Based PWM) and SVPWM to enhance the performance of three-level ANPC (Active Neutral Point Clamped) inverters. While RPS-PWM effectively reduces switching harmonics, it suffers from lower voltage utilization. In contrast, SVPWM achieves higher voltage utilization but struggles with harmonic suppression. The proposed Advanced Hybrid SVPWM technique addresses these limitations by maintaining the voltage utilization level of RPS-PWM while significantly reducing harmonic distortion and increasing the output Vrms. To validate the effectiveness of the proposed method, comprehensive PSIM simulations and DSP-based hardware experiments were conducted. Experimental results confirm that the Advanced Hybrid SVPWM achieves superior harmonic suppression compared to conventional RPS-PWM and SVPWM, while also delivering improved output voltage characteristics. These findings highlight the potential of the proposed technique for enhancing the performance of power electronic systems requiring high efficiency and low harmonic distortion.

Direct Torque Control (DTC) is widely recognized for its fast dynamic response and simplicity in controlling induction motors. However, conventional DTC suffers from drawbacks such as high torque and flux ripple, sensitivity to parameter variations, and poor performance under low-speed operation. This study proposes an enhanced DTC strategy for a modified six-phase induction motor (MSPIM) by integrating Fuzzy-Based Proportional-Integral-Derivative (FPID) control compared with conventional PID and Sliding Mode Control (SMC). The FPID, PID, and SMC controller are employed to regulate speed and flux, leveraging its adaptability and robustness to system uncertainties. The six-phase induction motor, with its inherent fault-tolerant capabilities and reduced torque pulsations, serves as an ideal candidate for high-performance applications. Results obtained using MATLAB Simulink show that the proposed control strategy significantly reduces torque and flux ripple, improves dynamic response, and enhances robustness against speed and load changing. This work highlights the potential of combining intelligent control techniques like FPID, PID and SMC to advance the performance of DTC in multi-phase induction motor drives, particularly in applications requiring high reliability and efficiency. Based on simulation results, the fuzzy PID inverter reduces the speed error and THD of the current and voltage waveforms, thereby improving MSPIM’s overall performance when compared to the regular PID and SMC.

Taking the control of high-power asynchronous motor in the straddle monorail vehicle test bench as the research object, the direct torque control (SVM-DTC) based on space vector pulse width modulation (SVPWM) and the vector control based on space vector pulse width modulation (SVM-FOC) method are analyzed in detail. The simulation system model of SVM-DTC and SVM-FOC for high-power asynchronous motor is established by using MATLAB / Simulink. Combined with the test method of the straddle monorail vehicle test bench, the control capacity requirements of the test bench are studied, based on which the simulation model is targeted to input speed and torque signals, and the speed control curve responsiveness, torque control curve responsiveness and torque fluctuation of the asynchronous motor under the two control methods are compared. The results show that the direct torque control based on SVPWM has the superior performance of small torque fluctuation, accurate speed control, fast torque response and strong robustness, which should be prioritized in the selection of the electrical system control scheme of the test bench.

Counter Rotating Permanent Magnet Synchronous Motors (CRPMSM) are increasingly favored in underwater application due to their high torque density, efficiency and ability to cancel out yaw inducing moments through the use of dual rotors spinning in opposite directions. However, ensuring synchronization between the rotors under varying load dynamic underwater conditions poses significant control challenges. To address these limitation this research proposed a Reinforcement Learning-Driven Model Predictive Control (RL-MPC) for optimizing the performance of CRPMSM in submarine propulsion systems. RL-MPC control architecture used a Twin Delayed Deep Deterministic Policy Gradient (TD3) reinforcement learning. The system is modeled in MATLAB/simulink with CRPMSM represented in d-q reference frame and driven by voltage source inverter (VSI) using Space Vector Pulse Width Modulation (SVPWM). The RL-MPC controller performance evaluated under three condition: constant speed with variable balanced load, variable speed with constant load and constant speed with unbalanced load variation. Simulation result confirm that the RL-MPC improves motor performance by enhancing speed tracking, reducing torque ripple, maintaining rotor synchronization improving transient response compared to standalone MPC. Quantitative comparison shows RL-MPC enhances dynamic performance comparatively over single MPC. The total harmonic distortion (THD) of stator current during unbalanced load resynchronization was enhanced from 9.3% (MPC) to 3.4% (RL-MPC), overshoot decreased from 30% to 16.6%, and settling time was enhanced from 1.4 s to 0.7 s. These enhancements validate RL-MPC achieves a 63.4% reduction in THD, 45% reduction in overshoot, and 50% enhancement in settling time under unbalanced load conditions. Finally the Lyapunov-based stability analysis confirms the closed-loop stability of the system.

This paper proposes an improved speed control method for a dual-induction motor drive powered by a single five-leg voltage source inverter. Generally, dual- and multi-motor drive systems are widely used in electric vehicles, traction systems and in several industrial applications. The proposed solution utilizes field-oriented control scheme as basis. The space vector pulse-width modulation technique was used to generate the output voltages. The main purpose of the proposed solution is to utilize the additional degree of freedom provided by a dual-motor drive system. The improved speed control system consists of two blocks: an additional computation block and a rotor flux position control block. The proposed control technique allows for effective control of the rotor speed of two independent three-phase IMs, regardless of load conditions. Under limited conditions, when the rotor speeds of both motors are the same, the proposed rotor flux position control allows to achieve higher modulation indexes and decrease energy losses as well. Simulation studies were carried out in PLECS software, the obtained results proved the effectiveness of the proposed control scheme. To identify the feasibility and effectiveness of the proposed control system, an experimental validation was conducted. Simulation and experimental results are shown and discussed in this paper.

A hysteresis space vector pulse width modulation (SVPWM) reconfigurable fault-tolerant method for single-phase voltage source multi-level inverter with current tracking is proposed. Firstly, the influence of single switch open circuit fault and double switches open circuit fault on the voltage vector of the inverter is analyzed, and on this basis, the equivalent replacement of the voltage vector is obtained by using the topology reconstruction of the inverter, and the redundant voltage vectors with overlapping positions are preferred for equivalent replacement. If there are no coincident non-fault vectors, the other non-fault vectors with the closest position and effect are selected. The fault-tolerant method does not need the switching operation between the main power switching device and spare power switching device of the inverter, and can directly control the on–off process of the inverter reconfiguration unit through the driving signal of insulated gate bipolar translator (IGBT), which is simple and stable. Under the conditions of single switch open circuit and most double switches open circuit, the output current of the inverter can accurately track the reference current.

The reliability assessment of electric machines plays a very critical role in today’s engineering world. The reliability assessment requires a good understanding of electric motors and their root causes. Electric machines mostly fail due to mechanical problems and bearing damage is the main source of this. The bearings can be damaged by mechanical, electrical, and thermal stresses. Among all stresses, the researcher should give special attention to the electrical one, which is bearing current and shaft voltage. This review paper introduces a comprehensive study of bearing current and shaft voltage for inverter-fed electric machines. This study aims to discuss several motor failure processes, as well as the sources and definitions of bearing current and shaft voltage. The different kinds of bearing currents are addressed and the parasitic capacitances, which are the key component to describe bearing current, are determined. Several measurement approaches of bearing current will be discussed. Furthermore, modeling of bearing current will be covered together with the machine’s parasitic capacitances. Moreover, the different bearing current mitigation techniques, as described in many papers, will be thoroughly addressed. The use of rewound multiphase machines for mitigation of bearing current will be proposed and compared to a three-phase machine. Finally, various pulse width modulation techniques of multiphase systems that reduce bearing current and shaft voltage will be investigated, and the findings described in the literature will be summarized for all techniques.

In the five-phase-inverter adjustable speed system, a five-phase two-level inverter usually adopts the nearest-two vector SVPWM (NTV-SVPWM) or the nearest-four vector SVPWM (NFV-SVPWM). The former one has a high-output-current harmonic, which increases the power losses, while the latter one has a low harmonic, but its sinusoidal voltage transfer ratio (VTR) is 0.812, which decreases load capacity. To improve the loading capacity and decrease the power losses of the five-phase-inverter adjustable speed system, a new space vector over-modulation method based on multi-vector weighting is proposed in this paper, and harmonic characteristics of the proposed over-modulation method are analyzed. The simulation results indicate that the proposed over-modulation method has a lower output voltage error than that with the traditional NFV-SVPWM and has a lower output current THD than that with the traditional NTV-SVPWM. The experimental results verify that the proposed method is correct and feasible.