Study Of Digital Spindle AC Adjustable Speed Drive System

The researches of this thesis are carried out around the study and development of adjustable speed digital drive system of permanent magnet synchronous motor (PMSM) with wide range of variable speed and high performance, including the analysis of the system structure, the intelligent control method and the design of the system.First of all, conventional vector control algorithm is dependent on the mathematical model of motor. Thus, the control performance of system is influenced to a great extent by the model precision and the parameters of motor. Based on artificial neutral network control theory, a MIMO neutral network PID speed regulator realizing the maximum torque with minimum current is conformed for a PMSM drive system. NARMA (Nonlinear Autoregressive Moving Average) neutral network current controller of PMSM is proposed and it in company with neutral network speed regulator composes the PMSM vector control system. A number of simulation and experiments show that the system not only has good performance both in dynamic and steady state but also avoids the adverse effect resulted from the inaccurate mathematical model and the parameter changes of the PMSM. Therefore, the system possesses a good self-adapting and robust.The paper presents a new method of how to select the neural input variables by the correlation coefficient of mathematical statistics. According to the absolute value of correlation coefficient, the degree of correlation between input and output variables can be estimated and selected or not, which not only increases the neural network mathematical model accuracy, but also reduces the complexity.For the accomplishment of the national 863-advanced project, the industry control computer is used as main control unite and the PWSM machine tools spindle drive system. The hardware and software of the system is studied and developed. Basing on the operating characteristics of the PMSM machine tool spindle drive system, a novel frequency multiplication circuits which can be switch to 2 or 4 times of base frequency is proposed in the paper. It resolves the paradox of using a same photoelectric encoder under high and low speed operating condition of motors.