Design of Printed Circuit Board Coils for Precision Engineering Linear Direct Drives

Aiming at high forces at low space in linear direct drives, favorable heat transfer conditions and high copper filling factors of the coils are of central importance [1]. For this reasons coils are mainly made of round copper wire and subsequently casted with impregnating resins or epoxy resins to increase stability and thermal conductivity. However, there are alternatives such as coils with rectangular wire, casted coils [2] or PCB (printed circuit boards) coils [3]. Due to the geometric design of linear direct drives PCB coils can be an alternative [4]. In this paper a coil in printed circuit board design is presented. The development and the process, from the selection of suitable PCB designs to optimization, assembly and comparison with conventionally round wire coils, is described. A linear direct drive is designed to compare the force-displacement characteristics and the increase of the temperature in static operation of the two types of coils. Slightly lower temperature of the overall system at the same mechanical motor parameters can be achieved with the PCB coil.