Vfd Drives: Everything You Need To Know

Vfd Drives: Everything You Need To Know

VFDs are the most advanced type of motor control system. They combine the benefits of a stepper motor with those of an electronic controller. In this article, we will cover everything you need to know about VFD drives: how they work, what they’re used for and how to choose one that’s right for your project.

How Does A VFD Work?

VFDs use a three-phase AC motor to transform the input voltage and frequency into an output voltage and frequency. The VFD controller regulates the speed by altering the amount of time each phase is energized during each cycle, which can be changed to allow for variable speeds within the motor’s operating range.

An electric switch called a contactor (also called a relay) is closed, allowing current from your home’s electricity supply to flow through two coils of wire wound around an axle in your motor. 

As this happens, magnetic poles inside each coil attract one another as they move past one another in opposite directions. This interaction causes them to rotate together along with their attached shafts until they’re stopped when they come back together at full rotation speed – that’s step 2!

The Power Circuit

The power circuit is the part of the VFD that converts the AC power from the utility company into DC power for the control circuit. It consists of an AC to DC (alternating current to direct current) converter and a rectifier. 

The converter uses three-phase input current to produce two-phase output voltage waveforms, which are then filtered by capacitors and diodes before being fed into each phase of your motor’s stator windings.

Vfd Drives

The Control Circuit

The control circuit of your VFD is critical to its performance, and you should take the time to understand what options are available.

  • Choose a control circuit that matches your application. For example, if you’re controlling a centrifugal pump, you may need an output frequency that matches the frequency at which the pump turns (typically around 60 Hz).
  • Choose a control circuit that matches your budget. The more sophisticated digital controls tend to cost more but can offer more flexibility and fine-tuning capabilities in future projects.
  • Choose a control circuit that matches your power requirements; if power isn’t an issue for now but might be later on down the road, go with something more basic now which will allow for upgrades later on without having to replace everything else first!

How To Choose A VFD

Now that you know about the advantages of VFDs, it’s time to choose one. Choosing a VFD can be tricky, especially if you don’t have experience with these kinds of drives. The following tips will help you choose a VFD that best fits your application:

  • Choose a VFD based on the type of load you have. For example, if you need an AC motor connected to a car brake system, use a soft start drive (SSD) because it has lower startup currents than other types of drives and can withstand high inrush currents during operation (like when braking).
  • Choose a VFD based on voltage and current requirements of your load. For example, if you want to control an LED light bulb with a 12V battery pack but only have 6V available at all times (because there’s no way for electricity from the battery pack itself until just before charging), then look for an LED driver instead of using an LED controller instead since they require less power overall due to being designed specifically for this purpose only!


Vfd Drives are a great way to save money and add efficiency to your manufacturing process. There are many different types, from those that use AC or DC power and control motors in different ways. We hope this article has helped you understand how these devices work, so that you can choose the best one for your application.

Yellow Blog