Difference between Frequency Converter and VFD

The frequency converter is constituted by the entire circuit AC-DC-AC-filter converting device, it has been widely used. Frequency converter not only can analog output indicators of different countries, but also provide clean and reliable, low harmonic distortion, high voltage and frequency stability in the design, development, production, testing and other applications sine wave power output for export of electrical manufacturers. The frequency converter is very close to the ideal AC power grid voltage and is able to output the network voltage and frequency of any country. Variable frequency drive(VFD) is organized by DC-AC-AC (modulated wave) and other circuits. Its output voltage waveform is a square wave pulse and harmonic component. The voltage and frequency vary in proportion and cannot be adjusted. It does not meet the requirements of the AC power supply.

Frequency converter vs. VFD


Frequency converterThe frequency converter has an overall coordination design. After years of technology accumulation, it can ensure stable and reliable operation of the power supply.
VFDThe VFD assembly shore power production is relatively simple because the major part is purchased. It is difficult to ensure that the parameters match with other elements.


Frequency converterFrequency constant during startup. Shore power can provide clean, reliable, low harmonic distortion, stable voltage and high-frequency sine wave power output, very close to the ideal AC power.
VFDIt is designed specifically for motor variable frequency startup, start voltage and frequency synchronization rise. Using VFD for modified power supply, electrical equipment may be affected, especially the controlled rectifier, communications equipment and so on.

Three-phase imbalance

Frequency converterConverting part apply star-shaped, each phase can be independently loaded, fully adapted to the three-phase unbalanced load. The unbalanced rate can be less than 3%.
VFDApply to invert, although the output is transformed into Y-output, the three-phase unbalanced load adaptability is still poor and may cause an increase in the reverse torque of the motor, making motor temperature rise, efficiency reduces, energy consumption increase and output depletion.


Frequency converterManufacturer R&D production. Manufacturers are very familiar with the frequency converter, if there are problems, they can troubleshoot the frequency converter in the shortest time on your site.
VFDIt is mostly purchased from other specializing manufacturers, if there are problems, you will have to remove the device and return it to the manufacturer (partly abroad). This will cause a long maintenance cycle, and the manufacturer is not responsible for matching the VFD to LC low-pass filter circuit. It will be difficult to completely solve the problem even on your site.

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