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In order to better address the problem of many high-order harmonics’ concentration in the output voltage, a novel five-phase piecewise-random-switching-frequency space vector pulse width modulation (PRSF-SVPWM) strategy is proposed for a five-phase voltage source inverter. Compared to the conventional random switching frequency SVPWM (RSF-SVPWM), the entire fundamental period of this method is divided into two half-fundamental periods, so the original switching frequency in a single fundamental period is randomized in segments respectively. During this process, parameters named the offset frequency and random frequency are defined and assigned reasonably. In this way, high-frequency harmonics in one period are spread into a wider range. Subsequent simulation and experimental results verify that the proposed random modulation strategy can further reduce amplitudes of harmonics near switching frequency and its integer multiples, even though within a narrow switching frequency range, and a satisfactory effect of high-order harmonic dispersion is finally obtained, which contributes to the application and popularization of random pulse width modulation strategies. [ABSTRACT FROM AUTHOR]

Dual stator-winding induction generator (DWIG) is one kind of emerging multiport electrical machine. It has become a promising direction in the last two decades, especially for stand-alone power systems and renewable energy power systems. This paper mainly focuses on the DWIG with similar-poles stator windings and cage-type rotor. An overview of DWIG and its system is given. Recent advances of this generator in system topologies, mathematical model, optimal design, control strategies, and performance analysis are presented. The developments and potential applications of the DWIG-based system are also discussed. [ABSTRACT FROM AUTHOR]

This paper presents an optimal scheme of excitation capacitor to decrease the capacity of static excitation controller (SEC) for dual stator-winding induction generator (DWIG) system applied in wind power generation. The investigations into reactive excitation power released by the excitation capacitor and SEC illustrate that the optimal excitation capacitor is not only related to generator parameters, speed range, and load, but also affected by wind turbine power curve. Based on the objective of minimizing the capacity of SEC, several methods are employed here to select an appropriate excitation capacitor. Through the analysis of DWIG control mechanism and model of SEC in the stator-voltage-orientation synchronous d– q frame, a decoupling control strategy using the space vector modulation is obtained. On the basis of this, the simulation and experimental works from the prototype of 18-kW six/three-phase DWIG wind power system are carried out to verify the optimal scheme. The results demonstrate the correctness and effectiveness of this optimization scheme. [ABSTRACT FROM PUBLISHER]

This letter proposes an integrated ac and dc hybrid generation system based on the dual-stator-winding induction generator with the static excitation controller (SEC). In this generator, not only the power winding can output the variable-frequency ac power, but also the control winding can provide the high-voltage dc power through the dc bus of the SEC, which implements the electric integration by only one generator. An instantaneous slip frequency control strategy is employed to guarantee the system a good performance. The experimental results verify the correctness and effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

In an interior permanent magnet synchronous motor (IPMSM) with segmented skewed poles, the armature reaction magnetic field (AR-MF) changes nonlinearly due to the saturation of the rotor magnetic barrier. Meanwhile, this varies under different excitation currents. As a result, it is difficult to be calculated by means of analytical methods. In this paper, the calculation model of AR-MF of IPMSM is first established by vector superposition method, without considering the saturation effect of rotor and the slotting effect of stator. In the second step, the virtual magnetic field of the rotor is introduced to quantitatively calculate the influence of local inhomogeneous saturation on the AR-MF. The latter is derived by combining both the subdomain method and equivalent magnetic circuit method. The complex relative permeance is also introduced to establish the AR-MF accounting for the stator slotting effect. To validate the AR-MF calculation method proposed, an 8-pole 48-slot IPMSM with segmented skewed poles is considered as a case study, showing a comparison by both with finite element (FE) results and the electromagnetic torque measured on a test bench. The model proposed in this paper shows high accuracy and fast computation with respect to FE analysis. [ABSTRACT FROM AUTHOR]