The frequency converter uses frequency conversion technology and microelectronics technology to change the frequency of the motor current to achieve motor speed control. The use of the frequency converter also ensures that people's equipment applications are easier and simpler, and better control of the equipment.
The basic principle of variable frequency speed regulation technology is based on the relationship between the motor speed and the input frequency of the working power supply, and the purpose of changing the motor speed is achieved by changing the working power frequency of the motor(mini offline ups power supply).
V/F control: In the motor, the voltage induced in the motor stator is proportional to the frequency and the air gap magnetic flux. If we reduce the frequency to keep the voltage constant, the air gap flux will increase. Therefore, to change the speed, we must keep the V/F ratio constant. V/F control technology has the advantages of low starting current and wide-range speed.
Open-loop V/F control: In order to achieve dynamic speed response, open-loop V/F control is used in the industry. In this method, the stator voltage and frequency are changed simultaneously. The air gap flux remains unchanged, and the V/F ratio remains unchanged.
Closed-loop V/F control: In closed-loop V/F control, a speed sensor is used to measure the actual speed of the feedback motor. After comparing with the set speed, the ratio of voltage to frequency is controlled to change and the V/F ratio is kept constant.
To maintain the stability of the output control signal, the actual operating signal must be compared and judged with the expected set value to form a closed-loop system to achieve PID adjustment control. The pressure transmitter installed on the pipeline samples the instantaneous pressure change of the pipe network system as a feedback signal to form a closed-loop control system.
If the constant pressure control is a non-linear, large inertia system, it is appropriate to use a combination of fuzzy control and PID. Fuzzy control is used when pressure fluctuations are large to speed up the response speed; when the pressure range is small, PID is used to maintain static accuracy. Fuzzy control can be realized by PLC and intelligent instrument, simple, convenient, economical, and practical.
When using the inverter, pay attention to understanding the principle of inverter speed control to facilitate correct operation. At the same time, ensure that the inverter is used within its specified range to avoid damage to the equipment. In addition, check the system when using the inverter. Whether the internal wiring and equipment are normal to ensure that people are safer when using the inverter. Of course, you should also pay attention to regular inspection and maintenance during the use of the inverter, so as to ensure the use of the inverter for a longer time.