The working principle of the single-phase ac motor

Only a single phase ac motor winding, is squirrel cage rotor. When a single-phase sinusoidal current in the stator winding, the motor can produce an alternating magnetic field, the magnetic field strength and direction interplanting sine law of change at any time, but is fixed on the spatial orientation, say again so the magnetic field is alternation pulse magnetic field. This alternation pulse magnetic field can be decomposed into two at the same speed and direction of rotation are instead of a rotating magnetic field, when the rotor static, the two rotating magnetic field generated in the rotor torque of two equal and opposite, making synthetic torque electric motor 12v 500w is zero, so the motor can't rotate. When we use the motor rotates in the direction of a force (clockwise), then the rotation of the generator stator rotor and clockwise direction magnetic field between the cutting lines of magnetic force movement decreases; The rotation of the rotor and counterclockwise direction magnetic field cutting lines of magnetic force between the movement. 

This balance is broken, the total electromagnetic torque generated by the rotor will no longer be wholesalemotor.blogspot.com zero, rotor spun along the driving direction. To make single-phase electric function automatically spin, we can add a starter in the stator winding, starting with the main windings in space by 90 degrees, starting winding to concatenate a suitable capacitance, makes differ with approximation in the phase of the primary winding current 90 degrees, the so-called split-phase principle. These two differ 90 degrees of electricity flow in time into the two differ 90 degrees of winding on the space, will be produced in the space (two-phase) rotating magnetic field, under the effect of the rotating magnetic field, the low rpm alternator rotor can be automatic starting, after starting, to speed up to a certain, with the aid of an installed on the rotor of the centrifugal switch or other automatic control device will start winding broken, only main winding work in normal working conditions. Therefore, starting winding can make short work. But there are a lot of time, starting winding is not broken, we call this kind of motor capacitor, single-phase motor to change this kind of motor, can be achieved by changing the position of the capacitor is concatenated.