The Technology Of Driving AC Servo Motor Based On FPGA

AC servo system is playing an increasingly important role in modern society. From national defense and military, aerospace and industrial applications, to our daily lives, AC servo is everywhere. After the AC servo drive technology based on MCU and based on DSP, the AC servo drive based on FPGA, for its advantages such as high speed and rich resource, is of great development prospects and research value. And it thus begins to attract domestic and foreign researchers’attention widely.The thesis studies the technology of driving AC servo motor based on FPGA. The main theories include vector control and SVPWM. In the vector control theory, the AC servo motor is equivalent to the DC motor through the coordinate transformation, thus it becomes easier to be controlled. SVPWM applies in the inverter module for controlling the IGBT. By superimposing several basic vectors, it’ll get a rotating stator voltage space vector.Hardware system is divided into two parts—the control part and the drive part, which deal with weak and strong power respectively. The control part mainly contains the FPGA system. It’s used for dealing with feedback signals such as the current and position feedback signals, and outputting the control signals of the IGBT. In the drive part, the control signal is amplified to drive the IGBT, while the output current is detected. The current value is fed back to the control part in the form of weak power signal.FPGA is applied to complete functions as follows:PID, coordinate transformation, SVPWM, communication with the encoder, sampling and filtering in the current detection. Trigonometric calculations are the key in coordinate transformation. Here a simple approach—look-up table is adopted. PID, SVPWM and calculation part of coordinate transformation are completed in DSP Builder. FPGA communicates with the encoder, in the form of request and response to get the rotor position information. In the current detection process, FPGA plays a role of Σ-ΔADC sampling filter, converting1-bit data stream to digital value. At the last, the system model and simulation result in Matlab are showed, and the SVPWM completed by DSP Builder is also simulated to verify its correctness. On these bases, the physical system is build, and the actual running state is researched and analyzed.