Linear induction motor drive for woodworking machine application

Abstract

Purpose – The purpose of this paper is to study a woodworking machine, in which a linear induction motor (LIM) is applied to feed the wood to be processed into the cutting saw. The LIM is optimally designed and the whole drive system is controlled by a programmable logic controller (PLC) to meet the industrial demands. Design/methodology/approach – Since the operation range is short, the LIM mainly works at the transient state of quick start and quick brake. Hence, the thrust force with a large slip ratio (hereafter called the starting thrust) is one of the most important issues in the LIM design. Finite element method is used to optimize the starting thrust while taking a specific variable voltage variable frequency (VVVF) drive into account. Findings – The LIM system directly drives the machine workbench where the wood is placed, eliminating the requirement of manpower to push the wood through the cutting saw, hence, greatly reduces the operation hazard. It has a higher reliability and longer service life than the conventional drive system employing a rotary motor with a ball screw mechanism. Originality/value – The LIM is an attractive candidate for the woodworking machine application, which can replace the complicated and relatively low-efficiency mechanism of rotary motor and ball screw. High starting thrust can be achieved by optimizing the LIM design, whilst the specific VVVF control is essential to ensure a good drive performance. The PLC is competent for both human-machine interface (HMI) and control of the inverter-fed LIM system, and is of high reliability in industrial environment.