An improved method of speed damping for a stepper motor with a smooth speed estimation

This paper presents an improved speed damping algorithm. By revealing the relation of the compensating coefficient to the speed and load torque, an optimal selection of the compensating coefficient is proposed. The vibration of the motor is reduced to a low level and the stability of the motor is guaranteed. In addition, this paper shows the implementation of a torque-based speed estimation in the damping algorithm. The speed is estimated smoothly and the estimation has no phase lag, in contrast with the speed estimation of conventional methods. This smooth estimated speed provides the ability to increase the sample rate of the control algorithm. This proposed damping method is implemented in a Field-programmable gate array (FPGA)-based stepper motor driver system. The experiment is performed at low speed to verify the correctness of the proposed compensating coefficient by demonstrating its effectiveness in suppressing vibration while using the torque-based speed estimation.