Ac frequency conversion speed is generally damping windings, the insulation of the motor rotor structure of dongguan brake motor is different from the synchronous motor as a general starting winding, the main role in the impact load, because of the speed change has induced current in the damper winding, when the electric current and the stator magnetic field to produce torque inhibit rotational speed changes, the smooth operation of the motor. Because of the induced current in the damped winding, the winding must be insulated to prevent running sparks. Therefore, high temperature resistant mica belt is adopted, and the insulation structure can withstand long-term temperature of 250 ~ 350℃ to ensure the normal operation of frequency conversion motor.