A drag and control system comprising a variable power motor and an automatic control system of the variable power motor, wherein the variable power motor mainly consists of a rotor, a stator, a housing, stator windings with a star point (o) and terminals (U1, V1, W1; U2, V2, W2; U3, V3, W3... Un, Vn, Wn); wherein the automatic control system comprises an intelligent controller, load current sensors (I1, 12), a voltage sensor, multi-stage winding switching switches (m) and multiple power factor compensation switches; the intelligent controller being configured to control the switching on and off of the multi-stage winding switching switches (m) and the multiple power factor compensation switches according to a comparison operation of load current and voltage signals of the load current sensors (I1, I2) and the voltage sensor and motor operation state information and through mathematical analysis optimization; the stator windings of the variable power motor are in the form of series windings whose powers are gradually reduced stage by stage according to the rated current (Ir) of the motor, and series nodes, L1, L2, L3... Ln, of the respective stator series windings are led out to the terminals (U1, V1, W1; U2, V2, W2; U3, V3, W3... Un, Vn, Wn), wherein the intelligent controller being configured to automatically switch and control the respective series nodes L1, L2, L3... Ln of the multiple stages of series windings, n being the number of nodes or stages of the series windings; a maximum rated current of the multiple stages of stator series windings is the rated current (Ir) of the motor, i.e. the rated current of the series windings near the star point, and rated currents (Ir1 to Irn) of respective stator series windings are respectively selected according to geometric progression, arithmetic progression or other discrete parameters of the rated currents (Ir) to complete the optimization of respective rated current (Ir1 to Irn) of the multiple stages of series windings; and the stator windings of the variable power motor are formed by embedding multiple stages of stator series windings in the same stator core slot, characterized in that the multiple stages of stator series windings are connected in segmented series stage by stage from the star point to the outside according to the magnitude of power of the windings, and the windings near the star point are series windings having a maximum power, the series windings are each connected at one end to form the star point (o), the other ends of the series windings are each connected to one end of a respective one of the next-stage series windings with a power next to the maximum power, while the other ends of the next-stage series windings with a power next to the maximum power are each connected to one end of a respective one of their next-stage series windings with a power next to the power thereof, and so on, until open ends of the series windings (Ln) with a minimum power are the leading-out terminals of the minimum power; series nodes of the series windings with the maximum power near the star point (o) and their next-stage series windings with the power next to the maximum power serve as the leading-out terminals of the maximum power, and so on; and then leading-out terminals of the next-stage power next to the maximum power are led out at the nodes of respective series windings, then the leading-out terminals of the still next-stage power, until the leading-out terminals (Ln) of the open ends of the series windings with the minimum power, and the intelligent controller being further configured to control the rated currents (Ir1 to Irn) or rated powers of the variable power motor led out by the respective leading-out terminals in order to increase gradually from small to large to realize a soft-start of the motor, and to decrease gradually from large to small to realize a soft-stop of the motor.