What is a variable frequency drive(VFD)? How does it work?
Variable-frequency Drive (VFD) is an electric power control device that controls the AC motor by changing the motor’s working power frequency using frequency conversion technology and microelectronic technology. The variable frequency drive is mainly composed of a rectifier (AC to DC), filter, inverter (DC to AC), brake unit, drive unit, a detection unit, micro-processing unit, etc.
Variable-frequency Drive adjusts the voltage and frequency of the output power supply by the internal IGBT breaks off. Provide the required power supply voltage basis on the actual needs of the motor to help the energy-saving and speed regulation. Variable frequency drive also has many protection functions, such as overcurrent, overvoltage, overload protection, etc. The continuous improvement of industrial automation demonstrates the widespread use of variable frequency drives.
Before the variable frequency drive invention, people use a dc motor or a vs motor with the built-in coupling machine to drop the engine’s speed. Variable frequency drive simplifies the work. Also, decrease the device volume and reduces the maintenance rate. However, high-frequency switching signals on the power line and motor line of the variable frequency drive will cause electromagnetic interference. The power factor on the input side of the variable frequency drive is generally not good, which will produce harmonics at the power supply end.
Variable frequency drive uses whether in small household appliances or large mill and compressor in mines. About a third of the world’s energy consumed by the motors that drive fixed-speed centrifugal pumps, fans and compressors, and market penetration of variable frequency drive is still low. Significant improvements in energy efficiency are one of the main reasons for using a variable frequency drive.
Variable frequency drive technology is closely related to power electronics, including semiconductor switching elements, converter topology, control and simulation technology, and control hardware and firmware advances.
Reference:
