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The traditional approach to power factor correction in industrial applications involves installation of capacitor banks. But, with the widespread use of non-linear loads, such as variable speed drives (VSDs), power factor improvement has become more difficult. The presence of harmonic currents cause power capacitors to absorb them, as capacitor impedance is inversely proportional to frequency. The effects are overheating and increased dielectric stress of power capacitors, which result in their premature failure. Capacitors can also interact with harmonics, leading to harmonic amplifications at resonant frequency, which can damage the capacitors or components of the system. Besides, high power factor cannot be achieved because of distortion power. These have imposed the need for a different approach to power factor correction, i.e. application of harmonic solutions. High power factor and low harmonics go together. This article analyzes phase shifting technique for harmonics mitigation. Industrial case study is presented to demonstrate the applicability of the proposed technique for harmonics reduction and power factor correction at the same time.

The most widely adopted category of the mid-range wireless power transmission (WPT) systems is based on the magnetic resonance coupling (MRC), which is appropriate for a very wide range of applications. The primary concerns of the WPT/MRC system design are the power transfer capabilities. Using the scattering parameters based on power waves, the power transfer of an asymmetric WPT/MRC system with the series-series compensation structure is studied in this paper. This approach is very convenient since the scattering parameters can provide all the relevant characteristics of the WPT/MRC system related to power propagation. To maintain the power transfer capability of the WPT/MRC system at a high level, the scattering parameter S21 is used to determine the operating frequency of the power source. Nevertheless, this condition does not coincide with the maximum possible power transfer efficiency of the system. In this regard, the WPT/MRC system is thereafter configured with a matching circuit, whereas the scattering parameter S21′ S21’is used to calculate and then adjust the matching frequency of the system. This results in the maximum available power transfer efficiency and thereby increases the overall performance of the system. Theoretical investigations are followed by numerical simulation and experimental validation.

In this study, the tuning of the rotor time constant (T r) parameter of the induction motor (IM) drive by introducing the minimum order linear recursive least square (RLS) estimator is presented. The proposed RLS estimator can be excited using the pulse train of the flux reference as the test signal or using any other variation of the flux reference resulted from a number of optimisation techniques. The RLS is designed for traction drives with the encoder and utilises the measured stator currents. The recursive implementation of the proposed algorithm is suitable for the robust online T r estimation at different modes of operation, including the free-shaft and regular loading condition. The performances and practical aspects of the proposed algorithm are validated through the variety of experimental results on the digitally controlled traction IM drive. Nomenclature v sd , v sq stator voltage components in the rotating synchronous dq reference frame i sd , i sq stator current components in the rotating synchronous dq reference frame ψ rd , ψ rq rotor flux components in the rotating synchronous dq reference frame R s stator resistance L m mutual (magnetisingΨ inductance