The working principle and characteristics of single-phase asynchronous motor

Single-phase asynchronous motor only needs single-phase alternating current, so it is easy to use, widely used, and has the advantages of simple structure, low cost, low noise, small interference to radio system, etc., so it is commonly used in household appliances and small power machinery with low power. . Our domestic single-phase voltage is 220V, and the foreign single-phase voltage is different from ours, eg: US 120V, Japan 100V, Germany, Britain, France, 230V, etc. Therefore, when using a foreign single-phase asynchronous motor, it is necessary to pay attention to whether the rated voltage of the motor is the same as the power supply voltage. The single-phase AC winding is connected to the single-phase AC to generate the pulse magnetomotive force, and the magnetomotive force can be decomposed into two rotating magnetomotive forces of equal amplitude and opposite rotational speed, thereby establishing a forward and reverse magnetic field in the air gap. . These two rotating magnetic fields cut the rotor conductors and generate induced electromotive forces and induced currents in the rotor conductors, respectively. The current interacts with the magnetic field to produce positive and negative electromagnetic torque. The forward electromagnetic torque attempts to make the rotor forward; the reverse electromagnetic torque attempts to reverse the rotor. These two torques are superimposed to be the combined torque that drives the motor to rotate. Whether it is a positive or negative magnetic field, the relationship between their size and slip is the same as that of a three-phase asynchronous motor. If the rotational speed of the motor is n, the slip rate for the positive magnetic field is: s + = (n1 - n) / n1 = s. For the reversing magnetic field, the slip rate is: s-=(-n1-n)/-n1=s. The main features of single-phase asynchronous motor are: 1. n=0, s=1, T=T++ T- =0, indicating that the single-phase asynchronous motor has no starting torque. If no other measures are taken, the motor cannot start. 2. When s≠1, T≠0, T has no fixed direction, it depends on the positive and negative of s. 3. Since the reverse torque exists, the combined torque is also reduced, so the overload capability of the single-phase asynchronous motor is low. When the capacitor split phase starting operation is started, the switch K is closed, so that the phase difference between the two winding currents I1 and I2 is about 90°, thereby generating a rotating magnetic field, and the motor is turned; after the rotation is normal, the centrifugal switch is opened and the starting winding is cut off. Working principle of the shimming single-phase motor After the stator has passed the current, part of the magnetic flux passes through the short-circuiting ring and generates an induced current therein. The current in the shorting ring impedes the change of the magnetic flux, so that the magnetic flux generated by the shorting ring portion and the portion without the shorting ring has a phase difference, thereby forming a rotating magnetic field and rotating the rotor. Before the motor is installed, the insulation resistance between the stator winding and the main winding and the auxiliary winding should be measured. The normal temperature resistance value is not less than 10MΩ. Otherwise, the winding should be dried and the bulb heating method can be used. The shaft extension diameter of the motor has been ground to the standard tolerance size at the factory. Therefore, the inner diameter of the pulley or other matching parts required by the user is required to be selected from the national standard. When installing, push or gently tap the shaft extension table. It is strictly forbidden to use a hammer to slam, otherwise it is easy to shake the centrifugal switch, causing the motor to start, damage the bearing and increase the running noise of the motor. Before installing the motor to the supporting machine, carefully check the bottom part of the motor for cracks and affect the mechanical strength. If any problems are found, it is forbidden to install and use. The motor should be mounted on a flat plate with mounting holes and secured with bolts that fit the foot holes. In order to ensure safety, before the motor is running, be sure to connect the grounding wire to the grounding screw of the motor and ground it reliably. The grounding wire should be a copper wire with a cross-sectional area of ​​not less than 1mm2. ----- Responsible Editor: Dalan Oil Pump Motor 02- Purchasing Consultant Copyright http:/(Dalan Motor) Reprint, please indicate the source http://news.chinawj.com.cn

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