Speed Control System Based On DSP And Its Application In Milling Machine Reform

Abstract:The X62w universal milling machine is a relatively old milling machine. The electrical control system controls spindle motor M1, feed motor M2and cooling pump motor M3. Both M1and M2are operated in mechanical governor, which makes them unable to realize speed stepless control according to the processed products and demands. Their poor accuracy, bad speed stablity and low efficiency have a great influence on production efficiency and product quality, so they cannot meet the modern production requirements. In an effort to solve these problems, the paper researches the AC speed regulation system of electrical system of milling machine based on DSP.The paper firstly summarizes the electric transformation background of X62w universal milling machine. Then it analyses the working principle and disadvantages of traditional milling machine and the method of electrical control transformation, and demonstrates the principle of frequency conversion technology. What’s more, it designs a variable frequency speed control system with core of intelligent components TMS320F2812A, which mainly includes the smallest unit of DSP chip, rectifier circuit, filter circuit, inverter circuit, detection circuits of bus voltage, detection circuits of phase current, detection circuit of motor speed and position. Furthermore, the paper analyses Field Oriented Control technology and the SVPWM modulation strategy of inverter,and the technology used in the variable frequency speed control system of the milling spindle motor. A software design, which mainly includes the main controlling procedure of milling machine, control procedures of M1, speed detection and update service, the current sampling procedure, SVPWM service, and the control procedures of M2and M3, is applied on the hardware platform to realize the stepless speed regulation of M1and M2and the coordination of three motors. Simulation results show the design is effective.The experiment has proved that the system improves the starting performance of M1motor, the anti-interference ability and the following performance of speed. Meanwhile, the machining accuracy and production efficiency has also been improved obviously. With the control of software, the three motors can realize linkage control to reduce the accident rate. Therefore, it is a good choice without increasing much cost.