Intheproductionprocessofsomeindustries,theproductneedstobewoundonthedrum,aproblemthatneedstobesolvedhereishowtomakeitsdiameterfromthebeginningtothegradualincreaseofthewholeprocess,keepthechangeoftensionandlinearspeedwithintheallowablerange?YLJseriestorquemotorshavesuchelectricalcharacteristics.