What is the difference between VFD and inverter? Can VFD be used instead of inverter? Today Xindun Power will analyze in detail as follows:
Firstly, let us understand the VFD. The output frequency of this machine can be changed back and forth between 0Hz and 400Hz. The main components are:
Rectifier (AC to DC)
Filter circuit
Inverter (DC to variable frequency AC, and then output to the load for use)
The main function of the inverter is to adjust the operating speed of the generator by constantly changing the frequency of the output power, and it does not need to work with batteries.
The inverter was designed to provide stable power to the load. Whether it is the output voltage or frequency, the output power is stable.
In daily applications, the VFD is mainly used to adjust the running speed of the motor, that is, to change the running speed of the motor by changing the frequency of the output power. Another is the soft start for inductive loads. For example: a water pump inverter is not inverter, but VFD that can input solar energy. During the operation of a water pump, the amount of water inside it will constantly change: sometimes the water pump pumps a full pump of water, and sometimes the water pump is just idling, with no water in it. This will cause a 1kw water pump to work at 1kw sometimes, and when the water pump is idling, the working power will instantly reach 6-7kw.
The water pump inverter, that is, the VFD, can adapt to the instantaneous power changes required by the water pump by changing the frequency Hz of the output power. For example, a 1kw water pump inverter can change the output power to the instantaneous power required by the water pump by changing the frequency Hz of the output power. Therefore, a 1kw water pump inverter can work with a 1kw water pump. If it is replaced with low frequency off grid inverter, it will need at least 3 times the output power to work with 1kw water pump: 3kw.
This statement may be a little difficult to understand. Xindun Power will use analogy here: you are irrigating farmland, and a water pipe can only output so much water. If you want the water flow to be stronger and irrigate the farmland farther away from you, then make the outlet smaller, so that the water will burst out and irrigate the farmland farther away from you. If you want to irrigate the farmland around you and make the water flow softer, make the outlet larger, so that the water flow will become smoother and will only slowly irrigate the farmland around you. The inverter is the "valve" that controls the size of the outlet.
The main function of the inverter is to adjust the unstable input power to relatively stable power for the load, because the Hz of the mains power will not change from 0-400Hz, and the load rarely changes suddenly from 1kw to 6kw. At the same time, the load needs a stable power supply, and a large change in power will damage the load. Therefore, the original intention of the inverter is to provide stable output power, and through a series of components, the output power, whether it is voltage, Hz or waveform, becomes infinitely close to or equal to the power type most needed by the load. This is a different design concept from the VFD.
Finally, the VFD is mainly used to solve the needs brought by the change of the motor running speed in real time, and does not need to have a power storage function, while the inverter, especially the off grid inverter, mainly provides power to users uninterruptedly, so battery operation is a regular configuration.
As a professional solar inverter manufacturer, Xindun Power offers a range of product solutions, including off grid and hybrid inverter, etc., covering home, industrial, and agricultural scenarios. If you have any questions about inverter and converter selection, please feel free to contact Xindun.
