The structure of the rotor magnetic circuit has an obvious effect on the eddy current loss of the rotor of the high voltage line start permanent magnet synchronous motor. In this paper, a 10 kV to 1000 kW high voltage line start permanent magnet synchronous motor is taken as an example. The two-dimensional electromagnetic field model of the motor with V-shaped permanent magnet arrangement is established by using the finite element method. The no-load back EMF and armature current of the motor are calculated, and the correctness of the model is verified. On this basis, this paper proposes a sector permanent magnet structure, compares the difference between the air gap flux density and the rotor eddy current loss of the two magnetic circuit structures, analyzes the advantages and disadvantages of the above magnetic circuit structure on the harmonic effect of the air gap flux density of the motor. The mechanism of the influence of different magnetic circuit structures on the eddy current loss of the rotor is revealed, which provides a reference for the design of a high voltage line start permanent magnet motor. © 2020 John Wiley & Sons Ltd