How to distinguish dc motor from ac motor?
Ac motor and dc motor two kinds big. (1) ac motor and its control ac motor divided into two categories, asynchronous motor and synchronous motor. The asynchronous motor according to the number of stator phase asynchronous motor is divided into single and two phase asynchronous motor and three-phase asynchronous motor. Three-phase asynchronous motor has simple structure, reliable operation, the advantages of low cost, widely used in industrial and agricultural production. 1. The basic structure of three phase asynchronous motor There are two parts: the structure of the three-phase asynchronous motor stator and rotor. (1) of the stator, the stator is fixed parts, motor function is used to produce a rotating magnetic field. It is mainly composed of stator core, stator windings and the frame. (2) the rotor, the rotor is the key to master the part, there are two kinds of rotor, squirrel cage and wound rotor. Master. Their respective characteristics and difference between cage type used for medium and small power motor (below 100 k), he has simple structure, reliable work, convenient in operation and maintenance. Wound rotor can improve startup performance and adjust the speed, size of air gap between the stator and rotor, will affect the performance of the motor, the general thickness of air gap between 0.2 1.5 mm. Grasp the connection method of stator winding
Relative decision, according to the purpose of the use dc motor energy saving, high power factor, but need to convert ac to dc, need to increase the current transformer, cause high cost; The ac motor is easy to use, the structure is simple, the relative noise is too loud, please make the decision according to the demand
The difference between dc motor and ac motor is, of course, the type of power supply. One is dc and one is communication. The stator of a dc motor is a fixed magnetic field, and the direct current is rotating within the stator by the electric brush of the rotor forming a changing magnetic field around it. In industrial enterprises, dc motors are generally used for standby machinery or security equipment that can be reliably run because of the relative reliability of dc power sources. As the input voltage changes due to dc motor speed can also change, so need to often speed used dc motor is also many, such as trolley, electric locomotive, and so on. Ac motor is the rotational force generated by the rotating field of the stator that inducts the electric potential on the rotor. Its speed is generally fixed. But because of its simple structure and convenient power supply, it is widely used in various enterprises and families. Small to household washing machine, vacuum cleaner, big to huge pump, machine tool and so on, all use ac electric machine. Since communication is easier to obtain and easier to deliver, most of the electric machinery we use today is driven by ac motors.
Points too much difference between dc motor and ac motor, first of all, the most obvious is the power of nature is not the same, the second is the structure of ac motor, general use most is the squirrel cage and winding rotor, stator is silicon steel sheet, and divided into permanent magnet dc motor and the excitation system, it depends on what a drag parts, such as a lot of step by step, or asked for a small place is more permanent magnet torque, that is to say the stator is permanent magnets, the rotor type winding type. Big or speed torque requirements, such as machine tool equipment, are generally of excitation system, is the rotor and stator is wound rotor, in terms of output torque and power of the motor, dc than exchange big start torque, especially at low speed, because use dc motor, basically need speed, and is mostly need to its low speed, ac speed regulation (in this case are infinitely adjustable-speed) is currently the best only can be frequency converter, at the time of low speed and full load or light load, torque is as good as dc motor, it
