Research And Design Of Digital Industrial Sewing Machine Controller

With the rapid globalization of the world economy and transferring of themanufacturing of global Industrial Sewing Machine (ISM), China has become thelargest base for producing ISM of the whole world. However, there still exists obviousgap in production technique for digital ISM with high performance between internaland external. And the market for high performance ISM has still been occupied mainlyby Germany and Japan.According to requirement of one domestic ISM manufacture, a kind of digitalservo system for ISM based on Permanent Magnet Synchronous Machine (PMSM) hasbeen studied and designed. First of all, SVPWM has been analyzed in driving PMSM.It has shown that SVPWM can eliminate the torque ripple occurred when the motorrunning at low speed effectively. Afterwards, a reliable method adopted for both speedand position measurement has been presented. With the method, photoelectric encodercan be substituted just only by3HALL sensors combined with the function of IC unitof SCM. Consequently, the cost of the system will be reduced dramatically. And then,considering about the control algorithm, a control strategy of single closed loop hasbeen established, and a control algorithm of nonlinear PI mixed with change ratedintegral has been proposed for speed regulation. Under the effectiveness of thealgorithm, the system is able to acquire nice dynamic and static performance definitely.And a “five steps” algorithm which can guarantee high accuracy for needle location ofthe system has been applied. At last, with the mathematic model created byMATLAB/SIMULINK, the validity and veracity of the control method for motordriving and speed regulating can be proved effectively.Finally, the hardware of the system was finished with Microchip’s16-bitsmicrocontroller, dsPIC33FJI16MC304. And the software was designed based on theresearch of control algorithm and simulation result. The report originated from aspecial ISM test platform indicates that system can satisfy with the performanceindexes of response time less than200ms, needle location error less than±5°, maximum rotation speed at4800rpm and power rating at400W.