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A non‐linear adaptive backstepping controller based on linear extend state observer (NABESO) is designed to track speed of PMSM. This study proposes a two‐channel strategy which is applied for the online elimination of the influence of unknown load torque and parameters disturbances. According to the strategy, an adaptive controller is designed to eliminate the load torque and parameters disturbance of the first channel, and a linear extended state observer is chosen in a feedforward method to observe the internal time‐varying parameters disturbance of the second channel as well as compensating the disturbances from the first channel. The proposed strategy can not only achieve online estimation of the load disturbance, but also suppress disturbances caused by the changes of all parameters, and to some extent, the negative transient response can also be avoided by abandoning traditional cascade control mode. Besides the functional advantages, the proposed controller is of pertinence and flexibility in parameters selection. Finally, the simulation and experimental results both display that the proposed strategy can effectively suppress the impact of internal and external disturbance on the PMSM control performance. [ABSTRACT FROM AUTHOR]

This paper indicates that rational design and precise control for the structure and shape of nanofillers are effective for achieving the desired permittivity and breakdown strength for high energy densities of polymer nanocomposites. Two types of KTa0.5Nb0.5O3 (KTN) nanoparticles with different shapes (NC-KTN and NR-KTN) were introduced into the PVDF matrix. The molecular dynamic simulation and the Brunauer–Emmett–Teller (BET) surface area proved that the nonbonding interaction energy is stronger in the NR-KTN/PVDF composite films due to the larger surface area of NR-KTN (30.96 m2 g−1). In addition, the interfacial polarization related to the shape of nanofillers further improved the dielectric permittivity of NR-KTN/PVDF composite films. Through the comparison between the experimental data and various theoretical models, we concluded that the geometric shape of fillers has a significant impact on the dielectric constant of composite films. [ABSTRACT FROM AUTHOR]

Using coupling agent isocyanatopropyltriethoxysilane (ICTOS) to modified nano-TiO2, the polyimide (PI) with different titanium dioxide (TiO2) contents (0, 1, 2, 3, 4, and 5 wt %) doped nano-composites were prepared by sol–gel method (PI/TiO2 ICTOS composites). The effect of ICTOS modification on polarization and time-to-breakdown properties of composites were investigated by thermally stimulated depolarization current (TSDC) method, dielectric, and Corona aging measurements. The TSDC spectra show that ICTOS modification enhanced α-peak intensity and make β-peak disappear in composites. Relevant trap parameters were calculated by an approximate model, and the results indicate that introduction of ICTOS is effective for the charge carrier traps, activation energy distribution in composites. Corona aging measurement show corona resistance was also sufficient improved in PI/TiO2 ICTOS composites. The changes of activation energy and intensity of traps in composites may be responsible for the corona resistance. [ABSTRACT FROM AUTHOR]

A high recoverable energy storage density polymer composite film has been designed in which the ferroelectric-paraelectric 0.85 (K 0.5 Na 0.5 NbO₃)-0.15SrTiO₃ (abbreviated as KNN-ST) solid solution particles were introduced into polyvinylidene fluoride (PVDF) polymer as functional fillers. The effects of the polarization properties of K 0.5 Na 0.5 NbO₃ (KNN) and KNN-ST particles on the energy storage performances of KNN-ST/PVDF film were systemically studied. And the introduction of SrTiO₃ (ST) was effective in reducing the remnant polarization of the particles, improving the dielectric properties and recoverable energy storage density of the KNN-ST/PVDF films. Compared to KNN/PVDF films, the dielectric permittivity of composite films was enhanced from 17 to 38 upon the introduction of ST. A recoverable energy storage density of 1.34 J/cm³ was achieved, which is 202.60% larger than that of the KNN/PVDF composite films. The interface between the particles and the polymer matrix was considered to the enhanced dielectric permittivity of the films. And the reduced remnant polarization of the composites was regarded as the improving high recoverable energy storage density. The results demonstrated that combing ferroelectric- paraelectric particles with polymers might be a key method for composites with excellent dielectric permittivity, high energy storage density, and energy efficiency.