Summary:What are the advantages and disadvantages of variable frequency motors? When buying a variable-frequency speed-regulatin...
What are the advantages and disadvantages of variable frequency motors? When buying a variable-frequency speed-regulating motor, we first need to understand the advantages and disadvantages of the variable-frequency speed-regulating motor, so that we can choose the variable-frequency speed-regulating motor more conveniently. Let us understand the advantages and disadvantages of variable frequency speed control motors:
The advantages of variable frequency speed regulation motors:
1. The high-speed adjustment ability is attributed to the efficient speed adjustment method. This is because after changing the frequency, the motor is still running near the synchronous speed, basically maintaining the extra slip. Only in the frequency conversion equipment system, there will be conversion loss, and due to the influence of higher harmonics, the loss of the motor will increase, and then the power will decrease.
2. The speed adjustment range is wide, generally up to 20:1, and it has a high speed adjustment capability in the entire speed adjustment range. Therefore, variable frequency speed regulation is suitable for occasions with wide speed regulation range and low load operation.
3. The mechanical properties are hard. When there is no automatic control, the speed change rate is below 5%; when the automatic control is selected, it can perform high-precision operation and control the speed fluctuation rate at about 0.5%|~1%.
4. In case the frequency conversion equipment fails, it can be taken out of operation and powered directly by the grid, and the pump or fan can continue to run.
5. It can also be used as a starting device, that is, the motor is started at a certain speed through the variable frequency power supply, and then the variable frequency power supply is disconnected. The motor can be directly connected to an industrial frequency power supply to accelerate the pump or fan to full speed. When the variable frequency power supply is switched to an industrial frequency power supply, an inrush current of 400% to 500% usually occurs, the grid voltage will drop instantaneously, and the motor will be mechanically impacted. In order to avoid this phenomenon, a starting reactor can be connected in parallel between the motor and the industrial frequency power supply to suppress the inrush current during starting. If the prime mover is a synchronous motor, "synchronous switching" is required.
Disadvantages of variable-frequency speed-regulating motors
1. From now on, the initial investment of the frequency converter is too high, which is the main obstacle to the application of pump or fan speed regulation and energy saving. However, with the development of electronic technology, product costs have gradually increased, and its application prospects have become increasingly broad.
2. The high-order harmonics generated by the waveform of the current or voltage output by the inverter are non-sine waves, which will have various adverse effects on the motor and power supply. If you use a PWM inverter or current inverter with multiple skills, you can greatly improve this problem.