A three-phase hybrid stepping motor drive system combined with position-sensorless closed-loop control

This paper proposes a drive system for a three-phase hybrid stepping motor, combining sensorless closed-loop control with conventional open-loop control. It is characterized by sophisticated control providing both prevention of pulling out from synchronism and suppression of natural rotor oscillation, without any position sensor attached to the motor shaft. A switching technique in chopper control which can enlarge the speed range controllable in the sensorless closed-loop control is described. Starting and stopping sequences are developed to reduce mechanical natural oscillation produced in the transient state. Finally, the proposed drive system is compared experimentally with a conventional constant-current open-loop drive system. It is shown that the proposed drive system can perform the switchover from starting to sensorless closed-loop operation within 20 ms, and can reduce the natural oscillation caused just after positioning. © 2000 Scripta Technica, Electr Eng Jpn, 131(3): 80–90, 2000