Due to the extensive role of nonisolated high step-up dc–dc converters (NHSDC)s in industrial applications and academic research works, many of these pulsewidth modulation converters have been presented in recent years. For each of these NHSDCs, some claims are introduced to verify its capabilities and features, which have been investigated in some review papers with different frameworks. Dissimilar to previous review papers, which have focused on the classification and derivation of voltage boosting techniques, this article aims to evaluate the converters from various topological and operational points of view and determine the superiority of each technique and converter according to applications. Some of these metrics are voltage gain, stresses, ripple, cost, power density, weight, size, control complexity, and components count, which lead to a comprehensive comparative study. Then, as the main purpose of this article, the effectiveness of these metrics is assessed to show how well they can lead us to fair comparison results. Moreover, some new figures of merit are proposed in this article to provide a helpful guideline in power electronic converters comparison studies. Finally, the feasibility discussion of single- and multiobjective figures of merit is followed by a general practical conclusion and outlook about the NHSDC structures.

Finding efficient and satisfactory energy storage systems (ESSs) is one of the main concerns in the industry. Flywheel energy storage system (FESS) is one of the most satisfactory energy storage which has lots of advantages such as high efficiency, long lifetime, scalability, high power density, fast dynamic, deep charging, and discharging capability. The above features are necessary for electric vehicles (EVs), railways, renewable energy systems, and microgrids. Also, electrical machines, power electronics converters, and control systems are the cores of energy transfer in FESS. Therefore, they have a critical role in determining efficiency, power rating, power factor, cost, angular velocity, and volume of FESS. So, in this study, the FESS configuration, including the flywheel (rotor), electrical machine, power electronics converter, control system, and bearing are reviewed, individually and comprehensively. Additionally, the mentioned components have been categorized to be a guide for future research. The investigated electrical machines are compared by Finite Element Analysis (FEA). Subsequently, our laboratory’s measurement results are reviewed experimentally showing the progress in the field of FESS, such as designing robust control algorithms and an Interior Permanent Magnet-Synchronous Reluctance Machine (IPM-SynRM) to use in FESS.

In this paper, a short-circuit protection of an IGBT, based on current measurement is proposed. The IGBT collector current estimate is obtained by filtering the voltage between the auxiliary emitter and the power emitter terminals of an IGBT module. The proposed scheme utilizes a large bandwidth analog circuit which enables to the detect fault current regardless of the current slope. According to the experiments, the proposed circuit can detect faults before desaturation of the IGBT, which is a major benefit compared to the traditional methods based on IGBT saturation voltage measurement.