How does a Variable Speed Drive Work
An AC variable speed drive, also known as an AC drive or a variable frequency drive (VFD) or an Inverter. This is a device that is used to control the speed of an AC motor. The basic function of an AC variable speed drive is to convert the incoming AC voltage into a DC voltage and then invert it back to an AC voltage with a variable frequency and voltage.
Here are the main components of an AC variable speed drive and how they work.
- The rectifier is the first component of an AC variable speed drive, it converts incoming AC voltage into a DC voltage, the rectifier is typically a diode or thyristor based rectifier.
- DC circuit. The DC circuit is a capacitor bank that smooths out the DC voltage and provides a stable voltage for the inverter section.
- The inverter is the heart of the AC variable speed drive, it takes the DC voltage from the DC circuit and inverts it back into an AC voltage with a variable frequency and voltage level. The inverter uses insulated bipolar transistors (IGBT’s) to switch the DC voltage at high frequencies.
- Control Circuit. The control circuit is responsible for monitoring the motor and adjusting the frequency and voltage of the output voltage from the inverter control the speed the speed of the motor, the control circuit can use different types of control such as open or closed loop and or vector control depending on the application.
Overall, the AC variable speed drive can control the speed of the motor by changing the frequency and voltage of the AC output. By varying the speed of the motor it is then possible to optimise the energy consumption of the motor, other advantages of using this method of motor control would be reducing the wear and tear on the motor and its connected mechanical driven application, this in turn will improve the overall efficiency of the system.
Working with IDS
IDS are an ABB Value Provider (VP) and have worked in partnership with ABB for over 20 years. So there is not much we do not know about variable speed drives and how they work. If you are considering adding this technology it is worthwhile having a chat with us to ensure you specify the right drive for your applications, you can call us on 0115 944 1036 or email [email protected]