Research on the Application of Copper Shield in Surface Mount Permanent Magnet Synchronous Motors Driven by Inverters

The losses in the rotor of surface mounted permanent magnet synchronous motors are mainly eddy current losses, and the copper shield can effectively reduce the eddy current losses. This paper study the impacts of different placement positions of copper shield and different carrier frequencies of inverters on the shielding effect of copper shield. Simulation was used to investigate this problem, and the results show that the rotor losses are much greater when the copper is located on the surface of the sleeve than when the shield is between the permanent magnet and the sleeve, it is more suitable to place the copper shield between the permanent magnet and the sleeve. Adding the copper shield can effectively reduce the rotor losses, and the losses is mainly concentrated in the copper layer. The rotor losses show a trend of first decreasing and then increasing with the increase of copper shield thickness. There is an optimal value for the thickness of the copper, which minimizes the losses of the rotor. The higher the inverter carrier frequency, the smaller the optimal copper shielding layer thickness.