Thrust Ripple Analysis And Control Model Research On Permanent Magnet Linear Motor

Based on the Liaoning Province Natural Science Foundation project named "Research of Control Methods ffor High Speed and High Precision Linear Servo System (No. 20022037)", the characteristic of permanent magnet linear servo motor (PMLSM) used for NC machines has been analyzed. In order to restrain the thrust ripple of PMLSM, the primary and secondary structures have been designed and analyzed based on electromagnetic field theory, DSP is used for designing the control system of PMLSM.The end and cogging effect are the main reasons for thrust ripple of PMLSM. The new structure scheme of PMLSM based on permeance modulated theory is brought forward, which is based on fractional-slot theory to realized the purpose of short pitch and distribute, this scheme can make the technics simple and the thrust ripple decrease. Using ANSYS which is a software of FEM to analysis the magnet field and thrust of PMLSM can prove this method is very effective to reduce thrust ripple, the experiment also testified the availability of this method.Using the self-shield characteristic of Halbach array to boost up the air gap magnetic field of PMLSM, the optimize design based on Simulated Annealing Algorithm (SAA) is used to trapezoid Halbach array permanent magnet. The result proved that this structure can not only increase thrust density but also effectively restrain thrust ripple. For PMLSM used chinaware pedestal, it can leave out the secondary iron yoke to reduce its volume and weight. The optimized structure can more reduce thrust tipple, which provides ideal condition for precision machining and high dynamic response of servo system.Based on vector control theory, TMS320LF2407A is used for constructing servo system model of PMLSM for NC machines and IR2130 is used to drive IGBT, which can improve control precision through both speed and current closed loop. The hardware is reasonable and has self-protection function. The software can realize the function of sample current, compute speed, transform coordinate, Space Vector Pulse Width Modulate (SVPWM), etc. This system has the characteristic of high precision and strong real time, which can make PMLSM satisfier the demand of high precision machining.