계기판용 저가형 마이크로 프로세서의 마이크로 스텝운전

This paper presents micro-step operation of low power stepping motor for display unit using a direct connection of low cost micro processor. The micro-step operation of stepper motor is very important in an indicating instrument such as speed and taco meter. The proposed system uses a PWM output and digital output pin of micro processor per phase winding for low cost implementation. In order to perform smooth positing for suitable application, a simple low pass filer and modified sine data table are introduced to reduce low frequency harmonics. Furthermore, S-curve function for smooth position reference and amplitude control of phase voltage according to acceleration and deceleration are proposed in this paper. The proposed voltage amplitude controller can change the phase voltage according to motor speed to compensate the back emf of high speed and to reduce the torque ripple in the low speed region. The proposed system is designed by the low cost 8-bit micro processor without any external memory and power devices. The effectiveness of the proposed control scheme is verified by the practical dashboard system.