The rotation of the single phase ac motor principle

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 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 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 electric motor 12v 500w lines of magnetic force between the movement. 

This balance is broken, the total electromagnetic torque generated by the rotor will no longer generator stator be 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, as shown in figure 2. Under the effect of the rotating magnetic field, the rotor can be automatic starting, after starting, to www.facebook.com/dongfeng.motor speed up certain, with the aid of an installed on the rotor of the centrifugal switch or other automatic control device will start winding disconnect, the 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. In single phase motor, the rotating magnetic field generated another method called shield electrode method, also known as single phase mask pole type motor. This made salient pole motor stator, which has two kinds of the poles and quadrupole. Each pole in a third - quarter pole face open place with full of small tank, as shown in figure 3, the magnetic pole is divided into two parts, on the small part of the suit on a short circuit copper ring, like pole to cover up this part, so called cover pole type motor. Single-phase winding set in the entire history of the magnetic poles, each pole of the coil is connected in series, the connection must make its polarity, in turn, according to the N, S, N, S arrangement. When the stator winding current in the magnetic main flux, according to lenz's law, which through the short circuit copper ring main magnetic flux in the copper ring produces a 90 degrees on the phase lag of the induced current, flux on single phase asynchronous motor the phase of the current and lag behind the main magnetic flux, its role and the capacitor motor starting winding, motor rotation to produce a rotating magnetic field.