Variable frequency drive torque control inverter vfd

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Customers of Precision Electric have been using variable frequency drives to better control torque on electric motor applications for a number of years. This posting is to help you decide what type of variable frequency drive will work best for your application.

For a new VFD application:

  • Research the motor and VFD specifications.
  • Research your application requirements.
  • Learn more about the VFD products that are available to you.
  • Understand the features of those VFD products to determine what is an appropriate solution for your application.

There are a several different types of Variable Frequency Drives. The following is a short summary of the three different types of drives that are available, and when these types of drives should be considered in an application:

V/Hz (Volts per Hertz) Variable Frequency Drives (VFDs)

The most commonly used and most basic VFD available; this product is for a basic application in pumps, fans, conveyors, blowers and others.  These applications do not require high starting torque, full motor torque at low rpm, and/or speed feedback.  Most V/Hz VFDs have adequate programming features for many applications.  Be certain adequate I/O and programming features are available to meet your application requirements.  This product is an inexpensive alternative to a phase converter since they will accept single phase input while providing three phase output.

Sensorless (Open Loop) Vector Variable Frequency Drives (VFDs)

The next VFD type that is commonly used in a lathe, mill or any application where full torque is require throughout the motor speed range. Sensorless Vector VFDs are are also referred to as open loop vector drives; these drives are more complex than V/Hz drives and should always be applied to applications where high starting torque and/or full torque operating at low RPM is required. If speed feedback and/or extremely complex programming must be considered in your application you CANNOT use a sensorless vector VFD. Sensorless vector/open-loop vector VFDs do offer complex programming to a certain degree, but when your application exceeds sensorless vector programming features, there is a third solution.

Closed Loop Vector Variable Frequency Drives (VFDs)

This next level of VFDs are more advanced. Applications that require accurate speed regulation and feedback from the motor and/or require complex programming will require a closed-loop vector drive. This type of VFD is often offered as a “three in one” and able to operate in all operating modes.

  • V / Hz (Volts per Hertz)
  • Sensorless (Open Loop) Vector and
  • Closed Loop Vector

These products are complex and extremely efficient when properly applied. Used in the most complex, advanced manufacturing facilities across the world, closed-loop vector technology has few limits in drive technology. The product features are phenomenal. Applications where these products are utilized provide superior speed regulation and torque performance.

Before choosing a drive for your application consult with a qualified integrator, distributor, or manufacturer who will ask all the right questions and make an appropriate recommendation.  Here at Precision Electric Inc we offer proper service and telephone support from when you, or your qualified electrician, are setting up the drive for your application. Call us today.

Ryan Chamberlin
Inside Sales, Customer Support
[email protected]
Call Toll Free: 1.877.625.2402