Permanent-magnet linear synchronous motor (PMLS-M) exist the problem of normal force fluctuation, especially in the servo feeding system of high-precision CNC machine tools, the normal force fluctuation can cause the feeding table in vibration and produce resonance with other moving components of the servo feeding system .Analysis shows that detent force fluctuation is the predominant factor. Adopt the methods of end-teeth optimization combine with skew or V-skew can effectively reduce the detent force fluctuation. By using the Fourier regression analysis and limited enumeration method to calculate the optimal parameters, and applying the layered finite element analysis for simulation. The results of simulation prove that with the precondition of the thrust force loss slightly, adopt those optimization methods can reduce the normal force fluctuation significantly.

The ripple normal force of permanent magnet linear synchronous motor (PMLSM) can directly deteriorate the machining accuracy of ultra-precision CNC machine tool which use linear motor direct drive. First, the normal force of PMLSM was calculated using finite element method (FEM) .then, id current compensate lookup table was established by indexing iq current, gap and position of mover .In order to reduce the ripple of normal force and keep the thrust steady, PMLSM current compensation control system was realized by injecting the id current to counteract the normal force ripples using field oriented control (FOC) method. The effectiveness of this proposed method is verified by the simulation using Matlab according to the comparison between the compensation and no compensation cases.

The thermoacoustic electricity generator system can convert heat from the low quality heat source such as automobile exhaustsolar energyindustrial waste heat etc into electricity. But battery Harvests a little charging power from the system due to the soft load characteristic, which restricts the application of the thermoacoustic electricity technology. In order to improve the Harvesting ability of battery charging power , a mathematical model of the thermoacoustic electricity generator battery system are established and a charging power harvesting control strategy is put forward in this paper. The modelingsimulation and control of charging power maximization harvesting are systematically investigated by computer-aided analysis in Matlab.

In order to reduce the cogging torque in dual-rotor permanent magnet (PM) ring torque motor, the expression of cogging torque is deduced on the motor, and the influence rules of the resulting cogging torque are analyzed with change the inner and outer slot opening widths. According to the dual-rotor PM ring torque machine, the method for reducing the cogging torque amplitude and leading a reverse phase torque curve by suitable selection of the inner and outer slot opening widths is proposed. The results of simulation show that selecting the appropriate slot opening widths can effectively reduce cogging torque by the finite element simulation method.

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