Research On Running Control Of The Industrial Sewing Machine Based On DSP

Performance can be improved and efficiency could be enhanced by applying the brushless direct current motor (BLDCM) to the Industrial Sewing Machine, which is controlled by the intelligent-controller. In this thesis, speed-trace is obtained by speed-current double closed-loop via the intelligent-controller, while space-orientation is obtained by the modified firm-torque expectable shift method. The achievement of such important function lays a good foundation for further research.Based on previous studies, this thesis was focused primarily on several aspects as follows:Firstly, comparisons were made between other motors and the BLDCM which is durable and has small-inertia and fast-startup advantage. In general, this machine is controlled by means of three-phase-six-state. The characteristics of the BLDCM are introduced according to both load's connecting mode and switch's mode. To match practice, three-phase-angle-connection and 2-2 route-mode were adopted in this thesis.Secondly, the mathematic model of BLDCM was established., which laid a foundation for double closed-loop. Following this, the operating mechanism of the machine was analyzed in detail, and then H/L-PWM-ON strategy was proposed to control the machine. It was concluded that the smallest torque-ripple and quick slowing-down could be realized by this strategy. To reduce further the torque-ripple, commutation-delay-compensation was adopted based on H/L-PWM-ON strategy.Thirdly, in this thesis some effective parameters were obtained by on-line testing in order to control the running of the machine, which was based on its mathematic model. Also, the excellent performances, including preferable anti-disturbance and speed-trace which were based on the speed and current closed-loop, were realized.In addition, details of its stop process were analyzed and four different methods were adopted respectively to make sure the precision stop-position. Compared to the firm-D time-adjustable method,commutation-delay compensation and the traditional firm-torque expectable shift method, the modified firm-torque expectable shift method could better finish the task.Following this, DSP-CMOS chip, which has excellent performance and is used in the motor-controlling field, was introduced briefly.At last, results and conclusions mentioned above were overviewed, and the following tasks are presented to improve further performance of the sewing machine.