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This research work designs an improved iterative learning control (ILC) with dc-link balancing capability for three-level neutral-point-clamped inverter-fed permanent magnet synchronous motors (PMSMs). Unlike the classical ILC, which depends only on information captured from the last iteration, the proposed ILC approach is capable of storing the data of the state errors from a number of preceding iterations. Henceforth, the designed control method incorporates the simple dc-link balancing algorithm. It encompasses the integration of essential dynamics, with a dual focus on achieving not only rapid dynamic response but also maintaining a satisfactory steady-state performance. The efficacy of the proposed control approach is validated by experimental findings implemented with a PSIM software package and an experimental PMSM test rig with a TMS320F28335-DSP, respectively. Therefore, the improved transient response and steady-state performance indicate that the suggested control approach outperforms the standard approach.

This article presents a reduction method of circulating current in parallel three-level inverters using modified discontinuous pulse-width modulation (DPWM) based on an interleaving scheme. The harmonics and current ripple are the same as that of a single inverter with the same current capacity as the parallel system with DPWM. An interleaved DPWM improves the output current quality. However, a circulating current is generated by the asynchronous phase carriers. The circulating current limits the power rating. To alleviate these problems, the proposed method reduces the high-frequency circulating current with switching frequency by 79% even at a high modulation index. The switching sequence and high-frequency circulating current are analyzed to prove the performance of the proposed method. The effectiveness and reliability of the proposed reduction method are compared to the conventional SVM. The validity of the proposed method is verified through simulations and experimental results.

This article proposes a generalized hybrid method (GHM) for permanent magnet synchronous motors that leverages the advantages of field-oriented control (FOC) in steady-state operation and model predictive control (MPC) during transient-state operation. The proposed GHM aims to achieve fast dynamic response, zero average steady-state error, low overshoot and computation time, and reduced voltage vectors (VVs) without the need for weighting factors tuning for multilevel inverters. To achieve these objectives, the GHM creates a single VV using FOC and merges it in the MPC. Furthermore, the fuzzy logic chooses the optimal VV and inserts its input–output to train the artificial neural network to directly select the optimal value and achieve fast selection behavior. The GHM was experimentally evaluated against conventional MPC, FOC, and recent conventional hybrid methods (CHMs) in different operating conditions. The results showed that the proposed GHM demonstrated a low computation time, fast dynamic response, and good steady-state performance. Additionally, the recent CHMs were found to suffer from large overshoot, whereas the proposed method exhibited stable performance and low overshoot.

Faults are a common issue affecting the reliability of power conversion systems. They can occur in any switching device of a power converter. Open circuit faults are one of the most common types of faults, and their early detection and tolerance are crucial to prevent severe effects on the system. In this article, an enhanced distorted current–voltage space vector pulse-width modulation (SVPWM) method that can effectively detect and tolerate different open circuit faults in multilevel converters is presented and illustrated. In the proposed method, changes in the output current and DC link voltage are detected first, and a specific look-up table is then generated for accurate detection of the faulty device. Subsequently, after the fault is detected, a modified SVPWM fault tolerance strategy is applied to mitigate the effects of the fault and restore the healthy operation of the system. The effectiveness of the proposed method is verified through simulation and experimental results.

This article proposes an improved integrated modulation strategy of dual-parallel three-level inverters to suppress leakage current. Dual-parallel three-level inverters are widely used in several applications, such as in photovoltaic systems, wind power generation, and motor drive systems to increase the power capacity. The current ripple of each inverter appears greater on the load side due to the parallel operation of inverters. Thus, asynchronous modulation methods, such as interleaved or integrated modulation, have been proposed to improve the output current quality of three-level inverters. These asynchronous modulations generate a significant leakage current due to limited common-mode voltage (CMV) reduction. In this article, the proposed five-level reduced leakage current space vector modulation (RLC SVM) strategy adopts a switching sequence that lowers the CMV frequency. The proposed modulation solves problems such as insulation breakdown and electromagnetic interference by significantly suppressing the leakage current of the existing integrated modulation. Thus, the five-level RLC SVM method reduces the CMV, ZSCC, and output current distortion, as well as the leakage current. The feasibility and effectiveness of the proposed modulation method are verified based on simulations and experiments.