Permanent magnet synchronous motor occupies an important position in the power system, however, due to its fixed polar logarithm as well as the limitation of its starting and synchronous operation by voltage, current, frequency and other conditions, it is difficult to meet different operating conditions. The three-phase written-pole synchronous motor is a special type of permanent magnet synchronous motor with permanent magnet to operate with variable polar logarithm. Based on the characteristics of three-phase written pole synchronous motor starting, synchronous operation and pole-changing operation, a d/q mathematical model can thus be established. The simulation results are summarized and compared with the common permanent magnet synchronous motor, thus verifying such characteristics of large starting torque, wide synchronous speed and fast pull-in synchronous running speed as embodied by the three-phase written-pole synchronous motor.