What is the frequency inverter working principle? We know that the synchronous speed formula of an AC motor is: n=60 f (1-s)/p, in which, N is the speed of the asynchronous motor, F is the frequency of the asynchronous motor, S is the motor difference rate and P is the number of motor poles.
From the above formula, it can be seen that the speed N is proportional to the frequency F. As long as the frequency F can change the speed of the motor, the motor speed adjustment range is very wide when the frequency F changes in the range of 0 to 50Hz. The frequency inverter is to achieve speed adjustment by changing the frequency of the motor power supply, which is an ideal way of achieving high efficiency and high-performance speed regulation.
The frequency inverter working principle is actually to convert the power frequency power supply (50Hz or 60Hz) into a variety of frequencies of AC power supply to achieve the variable speed operation of the motor equipment, in which the control circuit completes the control of the main circuit, the rectifier circuit converts the AC into DC, the DC intermediate circuit smoothly filters the output of the rectifier circuit, and the inverter circuit converts the DC power into AC. For inverters such as vector control inverters, which require a lot of computing, sometimes a CPU and some corresponding circuits are needed for torque calculations. Frequency conversion speed regulation is achieved by changing the frequency of power supply by the stator winding of the motor to change the speed.
There are many kinds of classification methods of frequency inverters, which can be classified according to the main circuit working mode, and can be divided into voltage-type frequency inverters and current-type ones as well. Besides, in accordance with the classification of switching methods, it can be divided into PAM control inverters, PWM control inverters, and high-load frequency PWM control inverters. As for the frequency inverter working principle, it can be divided into V/f control inverters, differential frequency control inverters, and vector control frequency converters, etc. Moreover, according to the classification of purposes, it can be divided into general frequency converters, high-performance special frequency converters, high-frequency frequency converters, single-phase frequency converters, and three-phase frequency converters, etc.
The energy-saving of the frequency inverter is mainly manifested in the application of fans and pumps. After the fan and pump loads adopt frequency inverter, the power saving rate is 20% to 60%, which is because the actual power consumption of the fan and pump loads is basically proportional to the cubic speed. When the average flow rate required by the user is small, the fan and pump use frequency conversion speed regulation to reduce their speed. As a result, the energy-saving effect is very obvious. The traditional fan and pump class use baffles and valves for flow regulation, so the motor speed is basically unchanged, and the power consumption does not change much.
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