For a three-phase asynchronous motor and load with a relatively large speed range, the use of a variable frequency motor, coupled with a frequency converter, can indeed save electricity.

 

 

Using frequency converter technology to drive a three-phase asynchronous motor, and adjust the speed within a certain range, which has the effect of saving electricity.The frequency converter will automatically change the frequency to reduce the frequency of the motor, and the operating current will always run between 80%, 50%, and 30% of the rated power. This will greatly reduce the motor's operating current and achieve the effect of power saving.If the two motors drive the same mechanical load and both work at 50Hz power frequency, the use of variable frequency three-phase motors only reduces the excessive starting current at startup (the frequency converter can make the motor soft start), and Ordinary three-phase asynchronous motor load has a starting current 5~7 times more.

 

In this case, the inverter can save electricity because it can soft-start the inverter motor (or V/F operation mode. In fact, the main purpose of the inverter is to change the start and operation of the motor through its unique conditions. In a certain sense, it is indeed energy-saving compared to the motor load without a frequency converter; it is only slightly higher in efficiency and power factor than other speed-regulating equipment.

 

Furthermore, whether the variable frequency speed regulator can be used to save electricity is determined by the speed regulation characteristics of its load.If it is a load such as a centrifugal fan or a centrifugal water pump, the torque is proportional to the square of the speed, and the power is proportional to the cube of the speed.As long as the valve is used to control the flow, and it is not working at full load, it can save electricity if it is changed to speed control.

 

When the frequency converter is used to reduce the dynamic speed of the variable frequency three-phase asynchronous motor to 80% of the original, the power is only 51.2% of the original.It can be seen that the application of variable frequency speed regulators in this type of load has obvious power saving effects.The main function of the frequency converter is speed regulation and soft start.Power saving is a side effect.In most cases, the load or speed requirements for equipment operation are high or low, and the power saving effect of the inverter is more obvious when the load is low and the speed is low.If the load or the required speed does not change much, and it runs at full load or full speed most of the time, or is only used as a soft start, there is no power saving effect.