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When fast voltage control is used in a power factor control, the ripple of the dc link causes current harmonics. This paper proposes a method to reduce the harmonic content of a fast voltage loop in a power factor correction, which can both produce low distortion during steady-state operation and fast recovery from a load transient. The performance is achieved by using a Takagi–Sugeno-type nonlinear controller for dc-link voltage control. The proposed nonlinear control is compared with linear proportional–integral (PI) control, which is tuned to meet the standardized regulations for the harmonic content in a 3-kW single phase power supply. The results show that the presented nonlinear voltage controller can maintain the dynamic performance of the linear control with reduced current harmonics. It is also shown that the used nonlinear control method requires only marginally more complex control algorithm compared to commonly used linear PI control. [ABSTRACT FROM AUTHOR]

Multiphase electric machines are known to have problems with stator current harmonics. The harmonics can be eliminated by various current harmonic compensation methods. However, using the active harmonic compensation can increase the required output voltage of the inverter supplying the machine. Because the maximum voltage is limited, complete elimination of the current harmonics may not always be possible. For such cases, this paper introduces a strategy for a partial compensation of the current harmonics. The aim of the proposed strategy is to provide a maximum reduction in the magnitude of the harmonics when the available voltage is limited. The strategy is verified by experimental results. [ABSTRACT FROM AUTHOR]

One of the most significant reliability issues in switching-mode power supplies is electrolytic capacitor degradation caused by aging. This paper proposes an output voltage transient analysis method to detect capacitor wear-out at the output stage of a step-down dc–dc converter. Changes in the converter output voltage dynamics are evaluated by analyzing the output voltage step response with respect to a decrease in the capacitance. The sensitivity of the method is assessed with respect to parameter variations using an equivalent main circuit model. The feasibility of the presented method is verified by experimental tests using a converter prototype. The results show that the presented method is practical and adequate for detecting capacitor degradation in various operating conditions. [ABSTRACT FROM PUBLISHER]

Presents a discussion on the paper, “A review of single-phase improved power quality ACDC converters,” (Singh, B. et al), IEEE Trans. Ind. Electron., vol. 50, no. 5, pp. 962–981, Oct 2003 [ABSTRACT FROM AUTHOR]