Study Of The Air-cored Permanent Magnet Linear Servo Motor And Driver System

The air-cored permanent magnet linear servo motor (PMLSM) and control system is studied in the thesis. On the basis of reading lots of references, several main works has been done as below:1. Analysis and design of the flat type air-cored PMLSM. The topology, winding construction and characteristic of the motor are introduced. The magnetic field is analyzed by "equivalent magnetomotive force method" and "equivalent magnetization intensity method". Comparing the analytical solutions with the FEA solution, the "equivalent magnetomotive force method" is proved more accurate. The analytical equations of magnetic flux density, thrust force and back EMF are deduced, and equations are proved accurate by FEA. The influence of the motor key dimensions to the magnetic flux density, thrust force and back EMF are analyzed. The empirical design equations of the key dimensions and characteristic parameters of the motor are proposed. A prototype is designed and manufactured, and the performance of the prototype is analyzed by FEA.2. Analysis and design of the tubular type air-cored PMLSM. The topology and characteristic of the axial array tubular type air-cored PMLSM are introduced. The influence of the PM dimensions to the magetic field is analyzed by FEA. The empirical design equations and parameters of the motor are proposed. The prototypes are designed and manufactured, and the magnetic filed, static and dynamic thrust, back EMF and inductance of the prototype are analyzed by FEA.3. Study of the driver and control system of the PMLSM. The mathematic model of the PMLSM under dq coordinate is built, and the principle of the field oriented control method is introduced. A three closed loop about position, velocity and current control system based on field oriented control is designed, and the software and hardware of the control system are introduced. At last, a low-cost position detecting method using linear hall-effect sensors is proposed. The detecting accuracy is analyzed theoretically and this method is also test by the experiment.4. Experiments and applications of the permanent magnet linear servo system. An operating platform of the flat type air-cored PMLSM is manufactured, and the performance of the motor is test. The tubular type air-cored PMLSM are applied in the food-cutting machines and elevator door systems. The experiments are carried out under different operational conditions and the performances of the motors are presented. Both of these two applications achieve good results. At present time, the food-cutting machines have been produced by ITW of USA. The patent of the elevator door system has been applied, the novel elevator door was shown on the "World elevator & escalator expo' 08", and the production has step into the survey stage.The original works of this thesis includes:1. Solving the magnetic field of the the flat type air-cored PMLSM by the analytical method-"equivalent magnetomotive force method" and "equivalent magnetization intensity method". The "equivalent magnetomotive force method" is proved more accurate by the way of comparing the analytical solutions with the FEA solution. The error of solutions solving by "equivalent magnetomotive force method" is bigger, so this analytical method has limitation. The analytical equations of magnetic flux density, thrust force and back EMF are deduced, and the influences of the motor key dimensions to the performance of the motor are analyzed.2. In the study of the tubular type air-cored PMLSM, the influences of the permanent magnet dimensions to the magnetic field of the motor are analyzed by FEA. The empirical design equations of the motor are proposed, and prototypes are designed. The tubular type air-cored PMLSM are applied in the food-cutting machines and elevator door systems and achieve good results.3. Using a low cost position detecting method by linear hall-effect sensors in the tubular type permanent magnet linear servo systems. Based on the analysis of the magnetic field of the motor, the accauracy of this position detecting method is analyzed theoretically and experimentally.