Designed for a special motor for variable frequency conditions, you can get Yang Zheng

Under variable frequency conditions, the torque at low frequencies (ie, the starting torque) approaches the maximum torque. That is to say, the starting torque of the motor under the variable frequency condition is not a problem, and it is not necessary to increase the rotor resistance to increase the starting torque like the conventional motor, and the rotor winding has no obvious skin effect when the frequency conversion is started. Therefore, the structure of the double squirrel cage or deep groove is unnecessary for the frequency conversion start. Under the same power, the special motor for variable frequency operation can design the rotor groove shape to be shallow and flat, the radial size is obviously reduced, the overall size and material consumption of the motor are reduced accordingly, and the motor efficiency is improved. This is a beneficial side of the use of frequency conversion conditions.

Harmonic current and corresponding harmonic magnetic field appear in the motor under variable frequency conditions. They cause harmonic losses and increase the heat of the motor. Harmonic torque can also occur, causing additional oscillations in the motor during starting. This puts new requirements on the motor design: choose a reasonable number of stator and rotor slots, and take appropriate chute measures to reduce the effects of harmonic torque. In addition, the harmonics in the motor are divided into two types: one is the time harmonic magnetic field excited by the current harmonics; the other is the spatial harmonic magnetic field formed by the discontinuous distribution of the windings. If the appropriate scheme is selected through simulation, it is worthwhile to properly compensate the two harmonics.

Therefore, strictly speaking, the traditional (ie sine wave) design of the motor needs to consider the capacity reduction operation during the variable frequency operation (because the harmonic loss is added to the motor); the special purpose motor of the variable frequency condition can greatly weaken the harmonics when it is designed and manufactured. influences. Therefore, weigh the effects of positive and negative, and design a special motor suitable for variable frequency working conditions, which can get the effect of positive and negative.