VFD electric motor is a general term for motors driven by frequency converters. In fact, the motor designed for the frequency converter is a special VFD electric motor, and the motor can achieve different speeds and torques under the drive of the frequency converter to adapt to changes in load requirements. The variable vfd frequency converter is developed from the traditional squirrel cage motor, changing the traditional motor fan into an independent fan, and improving the insulation performance of the motor winding. In occasions with low requirements, such as low power and frequency at the rated operating frequency, ordinary squirrel cage motors can be used instead.
Compared with ordinary motors that cannot be adjusted in speed, the main advantage of variable frequency motors is that they can realize infinitely wide speed adjustments, and secondly, they consume less power at light loads and low speeds; The loss and temperature rise are significantly higher than ordinary motors, and the noise and vibration are relatively poor. In addition, the high price and the difficulty in using and maintaining frequency conversion devices are obvious weaknesses, so don't blindly use frequency converters and vfd compatible motor.
Variable frequency motors require infinitely wide speed regulation, especially in applications where the high speed is above 100% of the power frequency and the low speed is below 20% of the power frequency. The load is often in a light-load state, and the speed is allowed to drop under light load, such as water pumps in water supply systems, escalators, air-conditioning air supply systems, etc., and there is a certain energy-saving effect at this time. Occasions where stepless speed regulation is required and soft start and/or soft brake are required. Where stepless speed regulation is required and the space occupied by the motor needs to be reduced.
The heat dissipation system of the variable frequency motor is different from that of the ordinary motor; the slot insulation is strengthened by the variable frequency motor. The working point of ordinary motors is basically at the inflection point of magnetic saturation. If it is used as a VFD electric motor, it is easy to saturate and generate a higher excitation current, while the VFD electric motor increases the electromagnetic load during design, making the magnetic circuit difficult to saturate; the insulation level of the VFD electric motor is generally For class F or higher, strengthen the ground insulation and turn insulation strength, and especially consider the ability of the insulation to withstand the impact voltage.
For the vibration and noise problems of the electrical power control devices, it is necessary to fully consider the rigidity of the motor components and the whole, and try to increase its natural frequency to avoid resonance with each force wave. The cooling method of variable frequency motors and ordinary motors generally adopts forced ventilation cooling, that is, the cooling fan of the main motor is driven by an independent motor.