Researches On The Key Technologies Of PMSM Servo Drive System On NC Machine Tools

Numerical Control (NC) technology and NC equipment are important foundation for Manufacturing Industry Modernization and make a direct impact on country economic development and overall national strength. They are related to country strategic position. NC machine tools are composed of the machine tool body and NC servo system. Servo system is an automatic control system which aims at mechanical displacement control directly. NC machine tool servo system control the cutting movement of each coordinate shaft and the servo system implements the movement instructions from the CNC device. The servo-driven system performance determines the performance of NC machine tools to a great extent. The maximum speed, track speed, positioning accuracy, and other important indicators of NC machine tools depend on the dynamic and static characteristics of servo system.In this paper, the schema of permanent magnet synchronous motor (PMSM) servo-driven system is introduced briefly. Based on above, the key technologies of internal power supply, fault diagnosis and software structure of servo drive are studyed and explored in-depth. Its main contents are:The flyback switching power supply mathematical model is analyzed in continuous current mode (CCM) and discontinuous conduction mode (DCM). 8-output flyback switching power supply based on TOP244 which works in continuous current mode is designed. The power has been used in the drives actually. The testing and operation of this power show that it meets the design requirements. At the same time, the design of 8-output flyback switching power supply based on M51995 which works in discontinuous current mode is introduced briefly.The fault diagnosis and protection provided a strong guarantee for the safe operation of servo drive system and the personal safety of staff, and the parameters input function by panel with other auxiliary functions further improves the intelligence of this driver. The common faults of Servo drive system are analyzed and classified. Faults handling matters are sorted out and the hardware and software designs are conceived for each handling matter. The specific implementation methods of fault handling matters and programs on FPGA or DSP are illustrated in detail. The parameters input function by panel is implemented by VHDL programming based on state machine and the values of parameters are stored automatically on DSP. The serial communication between servo driver and PC is implemented by SCI module of TMS320F2812.In addition to dealing with three closed-loop control tasks, the servo driver need to handle parameters input, fault diagnosis and protection, RS232/485 communications, CAN bus communications and other functions. It requires that TMS320F2812 has multitask real-time processing capability. Through the transplantation ofμC / OS-II real-time kernel on TMS320F2812, the running tasks are designed properly so that the overall software structure design is clear and its reliability and expansibility are enhanced. It will improve the efficiency of programming development.