Abstract:The function of replenishing propellant is needed on the in-orbit long-running spacecraft, and the replenishment process is realized by a floating connection mechanism which is driven by a stepper motor. On the premise of ensuring the stable in-orbit refueling of the spacecraft, considering simplifying the software design, the self-adaption closed-loop control scheme of stepper motor phase current is proposed, that is, based on hardware comparison result which is completed by a comparator, constant current chopping on the stepper motor phase current is performed by FPGA to control the error of the stepper motor phase current not to be greater than 10%, so as to ensure the smooth operation of the floating connection mechanism. In order to verify the control effect of the stepper motor phase current, the simulation and experiment methods are used to test. The test results show that the closed-loop control method based on constant current chopping performed by FPGA can effectively define the error of the stepper motor phase current within 10%.