Regarding frequency converters and frequency-driven motors
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Do all variable-frequency motors need an inverter in order to be used? I’ve heard before that a combination of an inverter and a regular motor can also achieve a certain level of frequency conversion – is that correct?
I’m not an electrical engineering professional, so my questions are quite simple. I hope those who are more knowledgeable can help me out. Thank you
A variable-frequency motor is essentially a regular motor to which an axial flow fan is added. Since the air volume generated by the motor’s fan is designed for operation at the standard frequency, the fan speed slows down when variable frequency is applied, which prevents it from effectively cooling the motor and removing heat from it. An increase in the motor’s heat can lead to premature aging and other damages to the motor’s wiring and other components. Therefore, an axial flow fan is added later for independent drive; adjusting the motor speed does not affect the fan’s air volume. Speed regulation requires frequency conversion for control; without a frequency converter, it is impossible to adjust the motor speed! That’s all I know about pump factories. I hope this can help you!
That’s correct; a variable-frequency motor has an additional axial flow cooling fan that is powered independently, compared to a regular motor, which ensures proper cooling at low speeds
Thank you very much for your answer. Do you mean that a variable-frequency motor has an additional cooling fan compared to a regular fan? A frequency converter is needed to generate variable-frequency current; is my understanding correct?
An inverter is mainly composed of a rectifier (converting AC to DC), a filter, another rectifier (converting DC to AC), a braking unit, a drive unit, a detection unit, and a microprocessor unit. 1. Why can the rotation speed of a motor be changed freely? *1: r/min – the unit for motor rotation speed; it represents the number of rotations per minute, and can also be expressed as rpm. For example: a 2-pole motor at 50Hz has a rotation speed of 3000, while a 4-pole motor at 50Hz has a rotation speed of 1500. In conclusion, the rotation speed of a motor is proportional to the frequency
Your answer is quite professional; thank you so much~. The frequency in China is 50HZ; so is a frequency converter used to generate a 40HZ current?
Yes! You’re too kind, brother! Are there any problems with the pump? You can communicate with me to improve together!
The frequency converter belongs to the control system, while the variable-frequency motor (which has a different operating voltage range from that of a constant-frequency motor) belongs to the actuator
We specialize in heat exchanger units, and sometimes we deal with variable frequency control for make-up water pumps. May I ask which company you represent?
This post was last edited by yuchenchf on 2017-3-1 17:10 – share everything you know about pump problems! Happy to help!