Energy efficient electric drivetrain employing magnetic spring for weaving loom applications

This article compares three drivetrains for the shedding mechanism of weaving loom applications, which have a strongly oscillating load pattern. The three drivetrains employ a permanent magnet motor without a gearbox. The first drivetrain uses only the electric motor (EM1) while the other two drivetrains use the electric motor with assistance of a separate or an integrated magnetic spring (EM2MS or EMMS respectively). The magnetic spring provides part of the load torque in a passive way. This results in a reduced power consumption. The optimal design and the performance analysis of the machines have been presented for the considered application using a 2D finite element model coupled with an optimization algorithm. To validate experimentally the theoretical results, the EMMS prototype is manufactured and tested with and without an external load. The employed load is a 4-bar linkage that emulates the behaviour of a shedding mechanism of a given weaving loom. It is found that employing a magnetic spring can effectively reduce the power consumption of the drivetrain by more than 40%. However, introducing the magnetic spring reduces the flexibility of the system. In addition, it increases the initial cost. Nevertheless, the higher initial cost of the drivetrain will be paid back by the lower energy consumption.