-DC bias will cause abnormal vibration of transformers. Aiming at such a problem, transformer vibration affected by DC bias has been studied combined with transformer core and winding vibration mechanism use multi-physical field simulation software COMSOL in this paper. Furthermore the coupling model of electromagnetic-structural force field has been established, and the variation pattern of inner flux density, distribution of mechanical stress, tension and displacement were analyzed based on the coupling model. Finally, an experiment platform has been built up which was employed to verify the correctness of model.

A novel field modulated magnetic gear (FMMG) with concentric configuration is proposed and introduced to the drive train for a wind turbine system, which eliminates the vibration, noise and lubrication problems of mechanical gearbox and avoids the size and weight issues of directly-driven wind turbines The efficiency and reliability are improved simultaneously. Based on the static field computations by finite element analysis, the dynamic model of synchronous generator and magnetic gear is established and the dynamic performance of the transmission system is studied. The electromagnetic design and simulation results are verified by the experiment of the 1kW FMMG prototype with gear ratio of 6.75：1.

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Introduce a piezoelectric energy generator (PEG) with support device excited by the magnetic coupling force between rotating magnets fixed on a rotator and nickel plate fixed on a piezo-beam. The influence of magnetic force (number of the magnets), rotating speed and the work condition of the piezo-beam (with support device or free condition) on energy generation of the PEG was investigated experimentally. The research results show that there are several optimal rotating speeds for the PEG to achieve peak voltage at speed range of 0 to 1200r/min. Under the distance of rotating magnets and the piezo-beam is given, the peak voltages rise with the increasing of rotating magnets number and rotating speed.The maximum peek voltages from the PEG with 2/3/4 rotating magnets fixed on the rotator are 14.4/18.6/20.2V respectively and optimal rotating speeds are 660/456/348r/min. The support device makes optimal rotating speeds move backward, exerts great influence on the rising phases of the peak voltages, prevents piezo-beam from deforming excessively and improve the reliability of PEG.

To improve the speed and dynamic adaptability of robotic arm trajectory planning, a collision-free optimal trajectory planning method combining non-uniform adaptive time meshing and bounding box collision detection was proposed. First, the dynamics and objective function of the asymmetric industrial robotic arm with three degrees of freedom (DOF) was formulated in the form of the dynamic optimization problem. Second, the control vector parameterization (CVP) was improved to enhance the computational performance of the problem. The discrete grid was adaptively adjusted according the trend of control variables. Then, a quick and effective collision detection strategy was used to avoid obstacles and to speed up calculation efficiency. The non-collision constraint is built by transforming the collision detection into the distance between two points, and then is combined into the dynamic optimization problem. The solution of the new optimization problem with the improved CVP leads to the higher calculation performance and the avoidance of obstacles. Lastly, the Siemens Manutec R3 robotic arm is taken as an example to verify the effectiveness of the planning method. The approach not only reduces computation time but also maintains accurate calculations, so that optimal trajectory can be selected from symmetric paths near the obstacles. When weights were set as λ1 = λ2 = 0.5, the solution efficiency was improved by 33%, and the minimum distance between the robotic arm and obstacle could be 0.08 m, which ensured that there was no collision.