Study And Design Of The Spindle Permanent Magnet Synchronous Motor And Its Drive System

The researches of this thesis are carried out around the study and development of high performance machine tool spindle permanent magnet synchronous motor(PMSM) and its drive system. Five parts are included in the works:First of all, concerning of the operating characteristics of the machine tool spindle drive system, the current control strategy of sinusoidal current vector control spindle PMSM is determined on the view of reducing motor's temperature rise and the invertor's capacity matched to the motor, improving the motor's output torque during constant torque operation, and increasing the maximum speed and the constant power speed-adjustable category during constant power operation. Of the current control strategy, the maximum torque/current control strategy is adopted during the constant torque operating, and the flux-weakening control strategy, including the popular flux-weakening control and the maximum input power flux-weakening control strategy, is adopted during the constant power control. The influences of several main parameters of spindle PMSM, including the noload permanent magnet flux, d- and q-axis inductances etc. on the performances of the PMSM are calculated and summarized, and the parameters design rules are determined based on abovecalculation and analysis on influence rules of the main design parameters on the. performance ofPMSM controlled with different current control strategies. The main measures and practical methods to improve the flux-weakening capacity of the PMSM are studied and presented;Basing on the analysis and comparison of the performances, especially the flux-weakening capacity of PMSM with different rotor structures, a novel PMSM rotor structure, which is suitable for flux-weakening and can improve the torque output capacity in the same time, is presented.Then, emphasizing on PMSM employed the presented rotor structure in this thesis, the thesis calculated, analyzed and studied PMSM's parameters thoroughly. Several key parameters, i.e., the noload flux leakage factor, pole arc factor, noload air gap flux density waveshape, and the d- and q-axis inductances of PMSM are concerned. The influences of different structure design data, different magnetizing manner, dimensions and specifications of the magnet employed, and different current components applied, on mentioned above key parameters are calculated and studied. Basing on above researches, the electromagnetic design of PMSM employed the presented rotor structure has been completed.As the maximum speed of the designed spindle PMSM is extremely high, the thesis evaluates the mechanical performance of the motor operating at the maximum motor speed, and completes the mechanical design of the motor in the 3rd part of the thesis. The mechanical strength and rigidity of two typical existing rotor structures and the presented novel rotor structure have been calculatedand studied applying 3-D finite element method(FEM), and researching results show that the two existing rotor structures can't satisfy the mechanical demands, but when manufactured with suitable material, the rotor structure presented by the thesis can behave well at the maximum speed;The rotor shaft's critical speed and mode of vibration of the designed spindle PMSM are evaluated and analyzed with the transfer matrix method, and the researching results show that the first order critical speed of the shaft designed is far higher than the maximum speed bï¿¡the motor, therefore, the resonance can be avoided and the operating safety of the motor can be assured;The manufacture techniques.and method of the presented rotor structure have been put forward, and special design concern, setting eddy current-isolated rings on the solid rotor, has been employed to reduce the eddy current loss;The design of motor shaft, bearings, and the selection of lubricant of the PMSM have been also studied in this part, and reasonable and practical realizing techniques are put forward.In the forth part of the thesis, the static and dynamic performances of the spindle PMSM drive system, which is combined with PMSM, control algorithms, speed controller and the current hysteresis controller etc., are studied with the developed digital simulating software. The speed sections of the PI speed controller are divided reasonably, and the control parameters are determined through simulation;The starting process of the PMSM and the motor's static performances, such as torque, power, current vector and speed, have been studied with simulation. The motor's performances as the speed demand and load varied suddenly have been studied. The related method and control equation for the braking of the PMSM safely and quickly are presented. A stator current control algorithm, which needs fewer calculation and scarcely affects the motor starting performance, has been presented.Finally, the configuration and realization of the designed PMSM spindle drive system are described. The control of speed and the vector current control strategy are realized basing on personal computer, and the current hysteresis controller is realized with hardware circuit. The detection of speed and position of the rotor, and the communication between the computer and the hardware circuit have been completed with the counter card and D/A card set in the expand slot of the computer, and the control software is programmed with Turbo C language.The test results of the developed PMSM spindle drive system well verifies the research works of the thesis.