The Research On NC Machine AC Servo Drive System

This paper is based on developing PMSM(Permanent Magnet Synchronous Motor) AC servo system of NC machine feeding and its application. The mathematical model of PMSM, rotor field orientation and PWM (pulse width modulation) method are deduced and analyzed. Some functional modules of AC servo system are studied and realized in low cost FPGA (SpartanIIE-XC2S300E). The AC servo system is applied to NC machine. It is important to the improvement of the high performance AC servo system and NC equipment. Firstly, the paper deduces servo control method of PMSM, adapts i d=0 to surface PMSM, creates mathematical model of PMSM, and analyses vector control principle of rotor field orientation. SPWM, equal zero pulse width modulation and SVPWM are realized by Verilog language, and each algorithm module is designed. Secondly, according to the functional requirement of AC servo control system and FPGA module design characteristics, the speed servo controller is divided into some functional modules, and these functional modules are designed individually and synthesized, this whole drive system design is finished. Finally, the AC servo speed driver is applied to the NC machine. This paper introduces the operating principle of the NC machine system, the NC system and feed drive system is adjusted, instruction book of NC and some working examples are compiled. By analyzing the performance of AC servo system, the conclusion is summarized that the AC servo system has quick reverse speed,short positioning time, and constant torque. The speed servo controller satisfies requirement of NC work, has better linear adjustable character and better dynamic performance.