Reduction of detent force caused by the end effect of a high thrust tubular PMLSM using a genetic algorithm and FEM

In order to meet industrial safety standards in eccentric presses, the detent force of the acting high force tubular permanent magnet linear synchronous machines (PMLSM) should be reduced. The detent force is caused by two components: the slot effect and the end effect. Both effects are based on the reluctance change between permanent magnet (PM) and stator teeth. The slot effect is already optimized by the closing slot technique which is proven by measurements presented in this paper. The main topic is the reduction of detent force by using auxiliary poles at the end of the machine. Therefore a special genetic algorithm (GA) is developed which rates the simulation results of the FEM and produces new auxiliary poles. The combined simulation tries to find an optimal size and position for auxiliary poles to reduce the whole detent force. The numerical calculations propose a minimized detent force caused by the located poles, which is independent from the length of the machines (2, 3 or 5 modules).