Can ordinary motors use a frequency converter?
The motor is adaptable to frequent start-up and braking As a result of the inverter power supply, motor can under low frequency and voltage start, in the form of no impact current and frequency converter is available for braking modes of the brake quickly, create conditions for the realization of the frequent starting and braking, and the mechanical system and electromagnetic system of the motor is in circulation under the action of alternating force, brings to the mechanical structure and insulation structure fatigue and accelerated aging problem. Low speed cooling problem First, the impedance of the asynchronous motor is not ideal, and when the power frequency is low, the loss of the high frequency harmonic in the power supply is larger. Second, ordinary asynchronous motor at reduced speed, cooling air volume and speed of three proportional to reduce, cause the low speed of a motor cooling conditions deteriorate, a sharp increase in temperature is difficult to realize the constant torque output.
Of course, there is a problem to note that the low frequency runs solve the motor fan heat
You can use it, but be aware of the heat dissipation of the motor at low frequencies, and if you run too long at low speeds, it will affect the life of the motor.
Motor insulation strength problem Small and medium frequency converters, many of which are controlled by PWM. He is about several thousand to more than 10 KHZ carrier frequency, which makes the motor stator winding to withstand high voltage build-up rate, equivalent to impose great impulse voltage gradient on motor, the motor of the turn-to-turn insulation withstand ordeal. In addition, the rectangular produced by PWM inverter chopper superposition of impulse voltage on the motor running voltage, would pose a threat to ground insulation of motor, the ground under the repeated impact of high voltage insulation can accelerate ageing. 3, harmonic electromagnetic noise and vibration Ordinary asynchronous motors, when powered by a frequency converter, can complicate the vibration and noise caused by factors such as electromagnetism, mechanical and ventilation. The internal harmonic interference of the different time harmonic and the electromagnetism of electromagnetism in the frequency conversion power supply, form various electromagnetic excitation forces. When the frequency of the electromagnetic wave is consistent or close to the natural vibration frequency of the motor body, the resonant phenomenon will be generated to increase the noise. Because the frequency of the motor is wide, the speed varies widely, and the frequency of all kinds of electromagnetic waves is difficult to avoid the natural vibration frequency of each component of the motor.
Yes, but there are differences, as follows: Ordinary induction motor can be controlled by frequency conversion, no difference in usage of frequency conversion motor. But because it is designed according to the frequency of labor frequency, the relative frequency conversion machine, the existence efficiency is low, the temperature rises high, the insulation is easy to age, the noise and the vibration, the cooling is different. The detailed analysis is as follows: A normal asynchronous motor cannot fully adapt to the requirements of variable frequency control. The following is the effect of the converter on the motor The efficiency of the motor and the problem of temperature rise Regardless of the type of frequency converter, different levels of harmonic voltage and current are produced in the operation, and the motor is running in the non-sine voltage and the current. The high harmonics will cause the motor stator copper consumption, the rotor copper (aluminum) consumption, the iron consumption and the added loss, most notably the rotor copper (aluminum) consumption. For asynchronous motor is close to the base wave frequency corresponds to the synchronous speed of rotation, therefore, higher harmonic voltage to a larger slip cutting rotor after conducting bar, will produce very big rotor loss. In addition, additional copper consumption due to the skin effect is considered. These losses will make motor extra heat, low efficiency, output power decreases, and such as ordinary three-phase asynchronous motor running in the inverter output non-sinusoidal power supply conditions, the temperature rise to increase 10% - 10%.
