FPGA based microstepping controller.

Abstract

This project describes the design, simulation and implementation of an FPGA-based microstepping driver to control a dual H-Bridge to properly commutate a bipolar perma- nent magnet stepper motor for precise-position tracking applications. The kernel of the driver is a microstepping mode algorithm implemented in two ROMs as look-up tables.This engine is used to generate the appropriate pulse width modulation (PWM) signals to control the current levels in the motor’s windings. Because the current patterns in the win- dings closely resemble sine waves with 90° phase shift, we used a sinusoidal (sine/cosine) approximations function to build the look-up table to drive the motor’s windings. The digital driver is developed with the Very high speed integrated circuit Hardware Descrip- tion Language (VHDL). The driver is synthesized using Quartus® II, the Intel®- FPGA software development suite tools, and targeted at an FPGA of the Cyclone-II family. Computer simulations are carried on Quartus II simulator. The results show the effec- tiveness and merit of this design process by testing several fractions of a full step (1/2,1/4 and 1/8). In addition, the real-time applicability of this driver is exemplifie do na permanent magnet bipolar stepper motor.