Design And Implementation Of The Control System For Stepper Motor Based On FPGA

A stepper motor is a kind of electromechanical component that can turn the electrical pulse signal into the mechanical angular displacement or linear displacement. Because of the advantages of low cost, precise control and non-cumulative error, the stepper motor is applied widely in many fields of production and life. This paper takes two-phase hybrid stepper motor as a control object. According to the analysis of stepper motor's characteristics and working principle, this paper design the schemes, which achieves two-axis linkage control and subdivision drive system of the stepper motor based on the FPGA.This paper is divided into two parts. In the first part, the paper studies stepper motor's linkage control. The process of production requires many motors to operate lots of devices to work together. In view of this situation, the paper points out that adopting the digital integral interpolation algorithm can achieve multi-axis linkage control of the stepper motor. The characteristics of the interpolation algorithm are to easily achieve the multi-coordinate interpolation linkage, the high-speed operation, the strong logical function, and the uniform pulse distribution, etc. On the basis of the deep analysis of the digital integral interpolation algorithm principle, this paper adopts the Verilog HDL hardware to describe language according to the finite state machine, and succeeds in compiling programs about the digital integral interpolation and designing the confirmative circuit of the interpolation coordinated control system. The outcome of the experiment shows that the design can meet the needs of both two-axis movements and a real-time control.The second aspect focuses on the subdivision drive control system of the stepper motor. While working with the low frequency, the resolution of the stepper motor is not high, which tends to cause oscillation and unsteady operation. Therefore, the stepper motor cannot meet the requirements of high-precision. For this reason, based on the analysis of subdivision drive technology principle, this paper applies SPWM sinusoidal subdivision method of current vector constant amplitude rotation to design a subdivision drive control circuit. The control circuit includes the address generator, the double-channel ROM, the data converter, the PWM modulation and the design of the digital converter. This method can have the step angle subdivided evenly, and can improve the smooth operation of the stepper motor. In order to make the stepper motor run smoothly, this paper also designs a hardware circuit board, and draws a drive circuit schematic by Protel 99 and makes a PCB board. Finally, centered on FPGA, the paper carries out a comprehensive test, which combines the two-phase hybrid stepper motor with the driver. The result of the test shows that the system hardware and the software design are reasonable and feasible, and that the operation of the stepper motor is improved, which has a certain practical value.