Novel Position Detection Method for Permanent Magnet Stepper Motors Using Only Current Feedback

In this paper, a position detection method using only current feedback is proposed for permanent magnet stepper motors. Using the Lyapunov stability analysis of microstepping, we show that the approximate position can be determined by the interpolation of the measured currents. The position estimation error in the constant velocity period is analyzed using the position tracking error of microstepping. A new compensation filter is proposed to reduce the position estimation error due to the mechanical dynamics. The Heydemann correction and the gradient searching method are used for calibrating the current signals. 16 phase-shifted sinusoids are implemented for the interpolation of the currents. The performance of the proposed method was validated by experiment.