Frequency conversion motor & # 8203; The use of variable frequency motor is more and more widely, the frequency conversion motor repair, need according to the characteristics of frequency conversion motor, adopt effective measures, to ensure the normal operation of variable frequency motor, frequency conversion motor repair technology in current and needs to attach importance to the quality of the point. 1, the electromagnetic characteristics of frequency conversion motor planning for general asynchronous motor, frequency conversion motor planning function parameter is the first consideration when overload ability, a function, power and power factor. And frequency conversion motor, is because of the critical slip at power frequency, able to directly start in the critical slip near 1, therefore, overload capacity and function is not need to think too much, and have to deal with the key problem is how to improve the motor's ability to adapt to the sine wave power supply. Methods generally adopted are as follows: 1)As far as possible, the reduction of the stator and rotor resistance. Reduce the stator resistance can drop fundamental copper consumption, to compensate for higher harmonic caused by copper consumption increase. 2)For possessed of higher harmonic current, should be appropriate to add the inductance of the motor. But rotor slot leakage resistance is larger the skin effect is also big, higher harmonic copper loss also increased. Therefore, the size of the leakage reactance of the motor should give attention to two or morethings arrives the rationality of the impedance matching within the whole speed range. 3)Frequency conversion motor of main magnetic circuit is planning in unsaturated state, one is to consider will deepen higher harmonic magnetic circuit saturation, 2 it is considering in low frequency, in order to improve the output torque and appropriate to increase the output voltage of inverter. 2, structure planning, planning structure first and consider non-sinusoidal power characteristics of frequency conversion motor insulation structure, the influence of vibration and noise cooling method, etc, generally pay attention to the following questions: 1)Insulation class, generally for F or higher, strengthen the insulation and line turn insulation strength, especially want to consider the ability of impact resistance voltage insulation. 2)Problem of vibration and noise of motor, motor components should be fully considered and all the rigidity, trying to improve its natural frequency, in order to avoid resonance occur with all the force wave. 3)Generally choose forced ventilation cooling, cooling method, namely, main motor cooling fan with independent motor drive. 4)To prevent shaft current, beyond the capacity of 160 kw motor should choose bearing insulation measures. Mainly prone to asymmetric magnetic circuit, can also occur shaft current, when combined with other high frequency weight of current role, together will greatly add shaft current, and then result in bearing damage, so often adopted insulation measures. 5)The constant power variable frequency motor, when the speed beyond 3000 / min, should choose a special grease, high temperature resistant to compensate for the temperature of the bearing.
