If with different resistance in the circuit of the motor resistance, mechanical properties of the motor will also change, motor in different load cases, can make a difference in current resistance pressure drop will increase along with the increase of current, the resistance pressure drop effect not only, also combined with the stator resistance as additional of stator resistance, have the effect of resistance adjusting performance, it is quite difficult to change the stator winding, but the increase in the motor winding loop an adjustable resistance motor load speed change motor speed control is a method of speed control