Electrical network & # 8203; The speed of the ac asynchronous motor is associated with who? In order to find out ac asynchronous motor speed about what factors, here will introduce the work principle of asynchronous motor again: first, asynchronous motor stator winding through to three-phase power supply, because of three-phase power supply phase on the phase difference between the current within 120 & deg; And the three stator windings on the spatial orientation also mutually sent 120 & deg; Will occur, so that the stator winding of a rotating magnetic field. Second, the rotating magnetic field stator winding, rotor conducting bar (Cage or winding)Will open the lines of magnetic force of a rotating magnetic field and induced current, thus the rotor induced magnetic field. Under the effect of lenz's law, the rotor will follow the stator rotating magnetic field same direction rolling, and the rotor speed is lower than the speed of the stator rotating magnetic field of 2% ~ 5%, which means the speed of the rotor speed is slower than the stator rotating magnetic field. If the assumption that the speed of the rotor and the stator rotating magnetic field is poor for s, so that the asynchronous motor speed = rotor speed = the stator rotating magnetic field & times; (1 -s)Therefore, need to control the speed of the stator rotating magnetic field, can also control the speed of the motor. Permanent magnet synchronous motor speed related to who? Magnetic field of permanent magnet synchronous motor rotor and the stator rotating magnetic field has nothing to do, it is a permanent magnets embedded by the rotor itself since the magnetic field, thus the rotation of the rotor lenz's law are not legally binding, just according to the principle of the same, opposites attract effect, and the rotor speed and stator magnetic field exactly,Is also known as synchronous motor) is thusPoor, that is, the speed of the rotor and the stator magnetic field s = 0, namely: the rotor of the synchronous motor speed = therefore, rotational speed = the stator rotating magnetic field of permanent magnet synchronous motor and ac asynchronous motor is the same, only need to control the speed of the stator rotating magnetic field, can control the rotational speed of the motor at the same time. How to regulate the speed of the motor by the last to know, whether it's ac asynchronous motor, or permanent magnet synchronous motor, need to regulate the speed of the stator rotating magnetic field, it can control the speed of the motor. The speed of the stator rotating magnetic field associated with the logarithmic power frequency and poles, detailed calculation formula is: the speed of the stator rotating magnetic field: n = 60 f/P type, n as the stator rotating magnetic field rotation speed (r/min); For the power frequency (fHz); P for magnetic pole logarithmic (Pole number in addition to the 2)。 According to the formula in section again, can be concluded that the type: ac asynchronous motor speed: n = (1 -s)60 f/P permanent magnet synchronous motor speed: n = 60 f/P type, s is the speed difference between magnetic speed and rotor speed,About 2% ~ 5%)。 According to the type we know, control of ac asynchronous motor and permanent magnet synchronous motor speed are the same, there are two ways: 1)Variable polarity method (That regulate P)。 2)Frequency conversion method (That regulate f)。 Past multi-purpose pole way to regulate the speed of the motor to change, but with the progress of semiconductor and electronic skills, electric cars are now regulate power frequency, frequency control of motor speed, to complete control of ac motor speed, and the stepless speed regulation. Frequency control of motor speed is not new in your life, let's now household air conditioning use frequency control of motor speed, have been regulate power frequency to regulate the temperature of the air conditioning. As to what is the principle of frequency conversion, how to complete the conversion, the that is electrical automation and electronic professional content, in this not a tautology.
