The main components of an AC drive (Frequency Converter, Frequency Changer)
AC drives (Frequency Converters, Frequency Changers) are used in a wide variety of industrial applications. For example, AC drives are often used with fans to provide adjustable airflow in large heating and air conditioning systems. The flow of water and chemicals in industrial processes is often controlled by adjusting the speed of pumps.
What's more, variable speed AC drives (adjustable speed drives) are commonly used in more complex and difficult environments such as water and wastewater processing, paper mills, tunnel boring, oil drilling platforms or mining.
But what's ac drive (VFD)?
The main components of an AC drive: rectifier, DC circuit and inverter.
The speed is controlled by changing the frequency of the electrical supply to the motor. The 3-phase voltage in the national electrical grid connected to a motor creates a rotating magnetic field in it. The rotor of the electrical motor will follow this rotating magnetic field. An AC drive converts the frequency of the network to anything between 0 to 300 Hz or even higher, and thus controls the speed of motor proportionally to the frequency.
Figure: The main components of an AC drive includes rectifier, DC circuit and inverter
1. Rectifier unit
The AC drive is supplied by the electrical network via a rectifier. The rectifier unit can be uni- or bidirectional. When unidirectional, the AC drive can accelerate and run the motor by taking energy from the network. If bidirectional, the AC drive can also take the mechanical rotation energy from the motor and process and feed it back to the electrical network.
2. DC circuit
The DC circuit will store the electrical energy from the rectifier for the inverter to use. In most cases, the energy is stored in high-power capacitors.
3. Inverter unit
The inverter unit takes the electrical energy from the DC circuit and supplies it to the motor. The inverter uses modulation techniques to create the needed 3-phase AC voltage output for the motor. The frequency can be adjusted to match the need of the process. The higher the frequency of the output voltage is, the higher the speed of the motor, and thus, the output of the process.
