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Due to the possibility of the occurrence of a fault in converters, performance improvement of a converter under faulty conditions is important. In this paper, for improving the performance of the three‐phase cascaded H‐bridge multilevel converters (CHB‐MLCs) with a single faulty cell, the quarter‐and half‐wave symmetry selective harmonic mitigation (SHM) modulation method as well as reducing the number of switching angles (NSA) has been used. Consequently, it helps to reduce the switching frequency (fs) and the number of sentences of the Fourier series thus simplifies the objective function. In addition, the proposed method enables the switching angles of a faulty cell to be transferred to other normal cells per phase. For this purpose, the switching angles of the cells are optimized so that at least one of the cells does not overlap with the other cells in the same phase. By employing the maximum modulation index under the faulty condition, the maximum capacities of the remaining DC sources are used and consequently, the line voltage drop in the output voltage is prevented. To produce a balanced line voltage, the fundamental phase‐shift Compensation (FPSC) method is employed. Simulation and experimental results are presented to confirm the efficiency of the proposed strategy. [ABSTRACT FROM AUTHOR]

The growth in distorting loads has given an interest in the design of three-wire active power filters, switching circuits which can be installed in an installation and generate harmonic currents to neutralize the loads' distorting current. With no neutral, the currents have two degrees of freedom and can be represented by two-dimensional (2-D) vectors. This approach leads to a control strategy which can compensate for balanced three-phase distorting loads. However, there has been a growth of single-phase distorting loads which give large neutral currents at triplen frequencies and which cannot be dealt with by the three-wire active power filter control. This paper reports the development of a three-dimensional (3-D) vector treatment of unbalanced three-phase circuits which can be used instead for the development of a control strategy. Simulation studies show that the control is effective, not only for the removal of harmonics, but also for the compensation of fundamental unbalance currents.

The harmonic contents of principal performance characteristics in an electrical machine are important due to several reasons, especially because they influence the machine acoustic noise generation capability. Therefore, they should be accurately calculated considering the various electromagnetic effects involved in the machine operation. Accordingly, this study proposes a detailed analytical model for predicting the time waveforms and harmonic contents of the principal performance characteristics of a double‐sided TORUS‐type non‐slotted axial flux permanent magnet motor with surface‐mounted magnets at steady state under any given loading conditions. The armature‐reaction magnetic field and inductances are exactly calculated considering both the effects of coil sides and end windings as well as that of the winding distribution. Most notably, the aggregate iron loss of machine and its influence on armature currents is precisely modelled based on the magnetic field distribution in iron parts. By establishing and solving the differential equation system of motor in the two cases with or without the neutral wire, the armature currents, speed and torque ripples, input/output powers, and copper and iron losses are all achieved with the entire harmonic content and highest accuracy. The comparison of results with those of finite element analysis and real test then validates the model. [ABSTRACT FROM AUTHOR]