The invention relates to a novel synchronous
electric motor and an
electric motor control system thereof, and realizes the special advantages of 'one
electric motor and three states' and 'one state and multiple characteristics'. The invention is characterized in that on the basis of the existing permanent magnetic synchronous electric motor used for an electric automobile and a controller thereof, an exciting winding is added on a rotor, and the current of the exciting winding is controlled by an electric
motor controller to change the intensity of a
magnetic field of the electric motor so as to change the external characteristics of the electric motor and achieve the target of 'one electric motor and multiple characteristics'. The characteristic overcomes the defects of insufficient torque and poor dynamic property when the existing permanent magnetic synchronous electric motor used for the electric automobile is used for climbing, simultaneously solves the problem of insufficient electric
motor speed when the electric automobile is in
cruise control or high-speed running, and completely meets the requirements on road conditions of the electric motor used for the electric automobile. An advanced topology and
control algorithm is adopted for the electric
motor controller adaptive to the invention, and the electric motor is controlled more efficiently, and has better dynamic property and a longer running range.