How do VFD drives work? To know the answer to the question, you need to first understand what a VFD drive is. A variable frequency drive is a device used to control the power consumption of a motor. VFD can be used to reduce the energy that the motor needs for its operation. Variable frequency drives can change the speed and torque of the motor, which is achieved by controlling the power frequency of the motor. If we need to get a variable output from the motor, then we can use VFD device instead of any other mechanical devices.
Basically, a VFD is a motor driver that controls the speed, torque, direction, and horsepower of a motor. There are many speed drivers on the market that can be used to control the motor, but none have all the features of a VFD. Therefore, by using VFD, we can control the voltage and frequency supplied to the motor. VFD is also known as variable speed drive or adjustable speed drive, etc. It is also known as an inverter because it is able to change the frequency of the output voltage and current. Because of all these features, VFDs are widely used in HVAC systems. So how do VFD drives work?
What is variable frequency drive working principle? Typically, a motor consumes more current than its rated current when connected to a power source. The motor rotates at a synchronous speed, so VFD is used to change this speed, which is achieved by changing the frequency of the voltage applied to the motor. Therefore, when the VFD is connected to the motor power supply, it will start the motor at a low frequency and then gradually increase the frequency. VFD converts electrical energy into any form required to control the speed, torque, and direction of rotation of an AC motor. The rectifier section of the VFD converts alternating current into direct current. This rectified DC current is then transmitted to an intermediate circuit consisting of an inductor and a capacitor. After that, it is transferred to the inverter section, converting the direct current into alternating current with variable frequency and voltage. This is done with the help of pulse width modulated signals. The desired output is generated with the help of semiconductor switches, which commonly are IGBT.
How do VFD drives work? Now we know the answer to it, but where is it used? VFD drives are used in the marine industries, for power generation and power positioning, and industries such as paper mills, steel mills, and cement plants, and they can also be used in the oil and gas industry for controlling pumps, compressors, turbines, and so on. VFD drives are used in HVAC systems, where they can be used in all variable torque applications, while for metallurgy, they can be used in power generation sections such as condensate pumps, forced ventilators, etc.