1. If a regular asynchronous motor is operated under non-sinusoidal power conditions of a frequency converter, the temperature rise of the motor will increase by 10-20%.
2. It affects the insulation strength of the motor; many frequency converters use PWM control, with a carrier frequency of several thousand to tens of kilohertz, which causes the motor stator windings to withstand a very high voltage rise rate, putting the inter-turn insulation of the motor to a very severe test.
3. Harmonic electromagnetic noise and vibration effects: When ordinary motors are powered by frequency converters, the vibration and noise caused by electromagnetic, mechanical, ventilation and other factors become more complex.
4. When a frequency converter is used for power supply, the mechanical and electromagnetic systems of the motor are subjected to cyclic alternating forces, which causes fatigue and accelerated aging of the motor's mechanical and insulation structures.
5. The motor's impedance is not ideal, but when the power supply is at a lower frequency, the losses caused by higher harmonics increase. In addition, the cooling airflow of a typical motor decreases proportionally to the cube of the speed at low speeds, resulting in very poor cooling conditions and a sharp increase in temperature rise.
Common motors have 4, 6, 8, 10, or 16 poles (p), with 6- and 8-pole motors being quite common. Why does using a frequency converter to power a common motor have an impact? Because common motors are designed for constant frequency and constant voltage, and therefore cannot fully adapt to the speed regulation requirements of a frequency converter.
