The rotation of the three-phase asynchronous motor principle

Three-phase asynchronous motor to spin the prerequisite is to have a rotating magnetic field, three-phase asynchronous motor stator winding is used to produce a rotating magnetic field. As we know, but that power facies phase difference is the voltage on the phase between 120 degrees, three of the three-phase asynchronous motor stator winding on the spatial orientation also sent 120 degrees, so, acmotortrading.blogspot.com when during a stator winding into the three-phase power supply, the stator windings creates a rotating magnetic field, its process is shown in figure 1. Figure to describe the points four moment of a rotating magnetic field to produce process. Current every change is a cycle, a rotating magnetic field in a week, i.e., the change of the rotation of the rotating magnetic field and electric current is synchronized. The speed of the rotating magnetic field is: n = 60 f/P type in f P is the power supply frequency, magnetic field of magnetic pole unit is logarithmic, n: revolutions per minute. According to the type we know, the speed of the motor and the pole number and the use of the frequency of the power supply, therefore, control of ac motor speed has two methods: 1, change the method of magnetic pole; 2, frequency conversion method. 

Use the first method, is now using the frequency conversion technology to realize infinitely variable speed permanent magnet generators for sale control of ac motor. Can also be found that the rotation of the rotating magnetic field direction is related to the phase sequence and the winding current. Phase sequence arrange A, B, C clockwise, magnetic field, clockwise if any two of the three power cord switch root, such as current bubbled into C phase windings, B C phase current into the B phase winding, the phase sequence into: C, B, A, necessary counterclockwise in magnetic field. Using this feature, we can easily change the direction of rotation of the three-phase motor. Rotor stator windings creates a rotating magnetic field, after conducting bar (cage) will cut the lines of magnetic force of a rotating magnetic field and induced current, the current in the rotor conducting bar and interact with a rotating magnetic field to electric motors price produce electromagnetic force, electromagnetic force produced by electromagnetic torque drive rotor rotating magnetic field along the direction of the n1 speed in the spin. In general, the actual motor speed n1 is lower than the speed of the rotating magnetic field n. Because suppose n = n1, rotor conducting bar and a rotating magnetic field, there is no relative movement, wouldn't cut lines of magnetic force, also won't produce electromagnetic torque, so the rotor speed gasoline generator n1 inevitably less than n. We called the three-phase motor asynchronous motor.

Motor delta connection,the following two configurations

Switch from star to triangle,motor delta connection,the following two configurations:W2 U2 V2,V2 W2 U2 As the motor magnetic generator terminal box standard outlet on the left.According to the FUJI company motor into current,two configurations have difference.Is there any difference between a connection?1,as long as you connect the power cord three position unchanged,such as L1,L2,L3 and U1,V1,W1 connected to the same,so the two configurations of the triangle and the y connection,is a steering,will not reverse;2,as long as you change the position of three power cords,or changing the phase sequence,then the two configurations of the triangle and the y connection,will reverse at the same time;3,in the Y-delta start wholesalemotor.blogspot.com main circuit,as long as you don't change the position of the three power cord connection such as L1,L2,L3 and U1,V1,respectively connected W1 phase sequence is changeless,then Y-delta start,switching process will not reverse!The season reference aromatic content of the reply:The results of the two methods is to remain unchanged. Will do. From the analysis I see two kinds of connection,the current in the coil is the first start with the runtime of the same. The second is the opposite,but the direction of rotation of the magnetic field is the same. Instantaneous polarity is opposite.Don't know will make

8500w gasoline generator much difference.

Commonly used asynchronous motor frequency control of motor speed control mode

Common induction motor variable frequency speed regulation control method usually has two kinds,namely the constant torque frequency control of motor speed and constant power variable frequency speed regulation.(1) the constant torque frequency control of motor speed.Simply adjust the frequency of the ac power,although can achieve the purpose of adjusting the motor speed,but will worsen motor operation performance.Balance equations,this is because the motor U1 material E1 K1N1f1 phi wholesalemotor.blogspot.com m = 4.44,if the supply voltage U1 is changeless,is reduced when the frequency of f1,main flux phi m would increase,this will lead to motor magnetic circuit saturation overly,increase the excitation current,core loss increase,the power factor decreased;On the other hand,if increase frequency f1,phi m reduced,decreased the output torque of the motor,the motor capacity is not full play.In motor learning,we know that the asynchronous motor output torque,T2 is proportional to the U21 / F21 so asynchronous motor in the process of frequency control of acmotortrading.blogspot.com motor speed,if keep U1 / f1 is constant,the power supply voltage and frequency proportional adjustment,namely before and after the output torque of the motor can maintain speed control is constant,constant torque control is currently the most widely used a way of frequency control of motor speed control.(2) constant power variable frequency speed regulation.The output small electric motors power of motor lamination the asynchronous motor P2 is proportional to the U21 / F21.Therefore in the process of speed regulation,if can keep the U21 / f1 is constant,the speed before and after asynchronous motor output power remains the same,namely the constant power speed regulation.Some transportation machinery,such as electric drive locomotives,urban rail transportation,trolley buses,etc.,hoping to realize constant power control of motor speed,namely when the motor speed is low,the output torque is big,can produce large enough traction locomotive,vehicle speed,motor speed,high output torque can be smaller (only need to overcome the running resistance).