VFDs are used in a variety of applications from fans to pumps to conveyor systems and many others. They provide an efficient way to control the speed and torque of a motor, helping to save energy costs by using less power. They are also a safety feature, providing protection against overloads and helping to avoid costly mechanical problems like conveyor jams and mechanical wear and tear.
A VFD uses an AC drive sub-system to vary the frequency and voltage of the incoming AC power in order to match its speed and torque requirements. This sub-system contains a rectifier, DC capacitors, an inverter and an AC output. The AC power goes through the rectifier first, where it gets converted to DC. This DC is then filtered through the capacitors before being sent to an inverter that changes the DC to an AC waveform. The AC is then connected to the motor, which rotates at a speed proportional to the inverter output frequency and voltage.
variable frequency drives can be either single- or three-phase. The differences between the two types are based on how they change frequency and voltage, and how they mitigate harmonics. Single-phase drives use a simpler method of controlling frequency and voltage, while three-phase drives are capable of more complex methods.
In addition to changing the frequency and voltage of the power, a VFD can also change its current draw. The reason why is because the power consumed by a motor is proportional to the cube of its speed, which makes it extremely wasteful if it’s not running at the proper load or process requirement. Using a VFD to reduce the speed can decrease the power consumption by 50% or more, reducing energy costs.
Another benefit of VFDs is the ability to reduce maintenance costs by removing carbon brushes and mechanical speed-control gearboxes. In addition, VFDs can help to protect equipment from damage by providing a controlled braking system for machines that are unable to stop on their own. This helps to prevent mechanical wear and reduces downtime caused by mechanical failures.
VFDs can also be used to provide smooth acceleration and deceleration for machines, which can reduce machine shocks or damage to product. This can be especially important for machines such as mixers, compressors, and pumps that require a high amount of acceleration.
One of the disadvantages of using a VFD is the heat it generates, which can lead to additional cooling costs. However, this can be avoided by installing a fan that blows out the hot air, or by putting the drive in a non-classified (free of flammable gases)
VFDs have become very popular due to the efficiency and cost-effectiveness they offer compared to traditional mechanical controls such as DC carbon brushes or belts. In fact, many facilities now operate their equipment exclusively with VFDs to realize the significant benefits they provide. For this reason, it’s vital that you’re familiar with the key features and specifications of the models available to ensure that you get the right fit for your needs.