Double capacitor series single phase motor

YL YY YC motors;Single phase motor refers to an asynchronous motor powered by a 230V AC single-phase power supply. Because 220V power supply is very convenient and economical, and household electricity is also 220V, single-phase motors are not only used in large quantities in production, but are also closely related to people's daily lives, especially as people's living standards improve day by day. The use of single-phase motors in household electrical equipment is also increasing. In terms of production, there are micro water pumps, refiners, threshing machines, crushers, woodworking machinery, medical equipment, etc. In terms of life, there are many types of electric fans, hair dryers, exhaust fans, washing machines, refrigerators, etc. But the power is less.
When a single-phase sinusoidal current passes through the stator winding, the motor will generate an alternating magnetic field. The strength and direction of this magnetic field change sinusoidally with time, but it is fixed in spatial orientation, so it is also called an alternating magnetic field. Pulsating magnetic field. This alternating pulsating magnetic field can be decomposed into two rotating magnetic fields with the same speed and opposite directions. When the rotor is stationary, these two rotating magnetic fields produce two torques of equal magnitude and opposite directions in the rotor, so that the combined The torque is zero, so the motor cannot rotate. When we use external force to rotate the motor in a certain direction (such as clockwise rotation), the motion of the cutting magnetic field lines between the rotor and the rotating magnetic field in the clockwise direction becomes smaller; the motion between the rotor and the rotating magnetic field in the counterclockwise direction becomes smaller. The cutting magnetic field line movement becomes larger. In this way, the balance is broken, the total electromagnetic torque generated by the rotor will no longer be zero, and the rotor will rotate in the pushing direction.
To make the single-phase motor rotate automatically, we can add a starting winding to the stator. The starting winding and the main winding are 90 degrees apart in space. The starting winding must be connected in series with a suitable capacitor so that the current of the starting winding is within the range of the main winding. The phase difference is approximately 90 degrees, which is the so-called phase separation principle. In this way, two currents that are 90 degrees different in time are passed into two windings that are 90 degrees different in space, and a (two-phase) rotating magnetic field will be generated in space.
Under the action of this rotating magnetic field, the rotor can start automatically. After starting, when the speed rises to a certain level, the starting winding is disconnected with the help of a centrifugal switch or other automatic control device installed on the rotor. During normal operation, only the main winding Work. Therefore, the starting winding can be made to work in a short time. But many times, the starting winding is not disconnected. We call this kind of motor a single-phase motor. To change the direction of this kind of motor, just change the terminal of the auxiliary winding.
In single-phase motors, another method of generating a rotating magnetic field is called the shaded-pole method, also known as single-phase shaded-pole motors. The stator of this kind of motor is made of salient pole type, and there are two types: two-pole and four-pole. Each magnetic pole has a small slot at 1/3 to 1/4 of the full pole surface. Divide the magnetic pole into two parts. Put a short-circuit copper ring on the small part, as if to cover this part of the magnetic pole, so It's called a shaded pole motor. The single-phase winding is installed on the entire magnetic pole, and the coils of each pole are connected in series. When connected, the polarities generated must be arranged in order of N, S, N, and S. When the stator winding is energized, a main magnetic flux is generated in the magnetic poles. According to Lenz's law, the main magnetic flux passing through the short-circuited copper ring generates an induced current in the copper ring that lags 90 degrees in phase. The magnetic flux generated by this current The flux also lags behind the main magnetic flux in phase, and its role is equivalent to the starting winding of a capacitor motor, thereby generating a rotating magnetic field to rotate the motor. 1) Capacitor split-phase single-phase motor
Figure (a) shows the principle wiring of a capacitor split-phase single-phase motor. Since the phase-shifting effect of the capacitor is relatively obvious, as long as a capacitor of appropriate capacity (generally about 20 to 50 μF) is connected in series with the starting winding, the current phase difference between the two windings can be close to 90°, and the resultant rotating magnetic field at this time is close to Due to the circular rotating magnetic field, the starting torque is large and the starting current is small. This type of single-phase motor is commonly used and can be left on as needed after starting (called a capacitor-run motor) or cut off (called a capacitor-start motor, performed by a centrifugal switch placed inside the motor). If you need to change the direction of the motor, just swap the outlet ends of any winding. At this time, the current phase relationship between the two windings is opposite.
(2) Resistor split-phase single-phase motor
The starting winding of this kind of motor has fewer turns and thin wires. Compared with the running winding, it has smaller reactance and larger resistance. When resistor-phase starting is used, the starting winding current leads the running winding, and the resultant magnetic field is an elliptical rotating magnetic field with a large ellipticity. The starting torque is small, and it is only used in no-load or light-load situations and has few applications. The starting winding of a resistive split-phase single-phase motor is generally designed for short-time operation. After starting, it is cut off by the centrifugal switch and maintained by the working winding. Figure (b) shows the principle wiring of a resistor split-phase single-phase motor. [1]
Shaded pole single-phase motor
A shaded pole single-phase motor is formed by embedding part of the stator magnetic poles in a short-circuited copper ring or short-circuit coil (group). Shaded pole single-phase motors include salient pole and hidden pole types.
When the stator winding is supplied with a single-phase alternating current, most of the pulsating magnetic field generated by it is directly coupled to the rotor through the air gap, while a small part of the magnetic flux generates induced magnetic flux when passing through the shaded pole copper ring and After being synthesized with it, it enters the rotor magnetic circuit through the air gap. According to Lenz's law, the induced magnetic flux always hinders the change of the original magnetic flux, and the induced magnetic flux lags behind the original magnetic flux in phase. In this way, there are two magnetic fluxes that are staggered by a certain angle in space and have a certain phase difference. The resultant magnetic field is a rotating magnetic field with a large ellipticity. The rotation direction of the shaded pole motor is fixed from the unshaded pole part to the shaded pole part. It has small power, small starting torque, simple structure, low price and easy maintenance. Shaded pole motors are generally used in small blower motors and fan motors. [1]