Analysis and Suppression of the Eddy Current Damping Force of the Cooling Plate of a Permanent Magnet Linear Motor

This paper proposes a new symmetrical cooling plate. It can significantly reduce the eddy current damping force of the water-cooled metal plate. To increase the thrust density of coreless permanent magnet linear motors, cooling plates must be placed on the armature surface to reduce the temperature rise that is caused by high electrical density. However, when the motor moves at a high speed, extra damping force will be generated in the cooling plate, which affects the thrust quality and precision of the permanent magnet linear motor. In this study, we elaborate the mechanism of damping force generation in the cooling plate and propose a new symmetrical cooling plate with low damping force. This paper introduces the topology of a linear motor cooling system and presents an analytical model of the eddy current distribution of a water-cooled plate. The surface current equivalence method is used to calculate the magnitude of the damping force. A new, symmetrical water-cooled plate design method is proposed. This method uses the eddy current vector synthesis principle to cancel the eddy currents that are generated in each region, and to reduce the damping force that is generated in the cooling plate during motor motion. Finally, a 3D simulation model of the motor system is established and an experimental platform is built. The correctness of the analytical model and the effectiveness of the cooling plate design are verified using a simulation and an experiment.