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A large number of harmonics will be generated in the process of transforming high frequency and high voltage alternating current (AC) into a constant frequency and constant voltage through a power conversion system when the high-speed motor is used as a generator. The phase-shifting reactor is used to eliminate harmonics for high-speed generator power conversion systems, and LCL filter and adjustable inductance filter are used to eliminate harmonics for high-speed motor power supply system in this paper. The adjustable inductance filter can adjust the inductance value in time according to the change of the output frequency of the inverter. The results verify the effectiveness of the methods used, and provide a theoretical basis for the wide application of high-speed motor by simulation.

High-speed motor is increasingly used in ultra-high precision machining and high-performance machinery. It is necessary to achieve closed-loop control of high-speed motor in order to realize high-performance motor control. The high-frequency and high-speed characteristics of high-speed motor have brought great difficulties for its realization of closed-loop control. The performance of the hexagonal flux direct torque control (DTC) method that can reduce the switching frequency of power devices is researched for high-speed synchronous motor in this paper. After adopting this control method, the harmonics in the motor current and torque can be suppressed by adopting an appropriate filtering method. The same effect as the conventional DTC can still be achieved. It provides a basis for the application realization of the high-speed synchronous motor control system.

In this paper, the pavement performance of recycled hot mix asphalt with 30% recycled asphalt pavement (RAP) content is studied by mix design, splitting test, freeze-thaw splitting test and dynamic modulus test. The results show that the recycled hot mix asphalt with 30% RAP content has better high-temperature deformation resistance than hot mix asphalt, but low temperature performance is slightly worse, and the water stability is not much different. It is proved that the road performance of recycled hot mix asphalt with 30% RAP content is the same as that of hot mix asphalt. Recycled hot mix asphalt with 30% RAP content can be widely used. The flexural creep test data at different temperatures were fitted to the exponential decay function, which proved that the recycled hot mix asphalt conformed to the generalized Maxwell model, and provided parameters for the establishment and analysis of the viscoelastic mechanical model of the recycled hot mix asphalt.

ZnO nanorods-nanosheets (NR-NS) hierarchical nanostructure consisted of long nanorod and thin nanosheet branches have been built on a stainless steel mesh via a two-step hydrothermal growth process. The related structures and morphologies of the as-prepared products were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The XRD results confirmed that the obtained samples were wurtzite hexagonal structured ZnO. The FE-SEM observations showed that the smooth surfaces of nanorods were covered by nanosheets, resulting in the enhancement of internal surface area. It was found that trisodium citrate played a crucial role in the formation of ZnO NR-NS hierarchical nanostructures, and accordingly, the rational growth mechanism was suggested.