Sep 13, 2021, split-phase single-phase motor
The split-phase single-phase motor uses a capacitor or resistor string to shift the phase of the inductive start winding, so that the current phase of the start winding and the working winding is staggered, which is the so-called “phase separation”.
(1) Capacitor split-phase single-phase motor
Since the phase shifting effect of the capacitor is relatively obvious, as long as a capacitor with a suitable capacity (usually about 20-50μF) is connected in the start winding, the current phase difference between the two windings can be close to 90°, and the resultant rotating magnetic field is close to Because of the circular rotating magnetic field, the starting torque is large and the starting current is small. This kind of single-phase motor is widely used, and it can be retained (called a capacitor running motor) or cut off as needed after starting (called a capacitor starting motor, which is executed by a centrifugal switch placed inside the motor). If you need to change the direction of rotation of the motor, you only need to swap the outlet ends of any winding. At this time, the current phase relationship of the two windings is opposite.
(2) Resistance split-phase single-phase motor
This kind of motor has a small number of turns in the starting winding and a thin wire. Compared with the running winding, the reactance is small and the resistance is large. When the resistance split-phase start is adopted, the starting winding current is ahead of the running winding, and the synthesized magnetic field is an elliptical rotating magnetic field with larger ellipticity, and the starting torque is small. It is only used for no-load or light-load occasions and has less application. The starting winding of the resistance split-phase single-phase motor is generally designed for short-time work, and is cut off by a centrifugal switch after starting, and the working winding maintains operation.
Shaded pole single-phase motor
A part of the stator magnetic poles are embedded in short-circuit copper rings or short-circuit coils (groups) to form a shaded-pole single-phase motor. Shaded pole single-phase motors include two types: salient pole and hidden pole.
Post time: Sep-13-2021