Trickle-down technology has resulted in modern micro VFDs with capabilities formerly available only on top-tier models.
Kevin Kakascik, Technical Marketing Engineer with AutomationDirect, wrote an article for the May/Jun 2022 issue of InTech titled Micro VFDs Gain Macro Features. This article points out the many advanced features now available even on micro VFDs, which help users in a variety of applications.
Electric motor speed control is essential for all types of industrial applications, such as with pumps, fans, machinery, and much more. A long time ago, DC motors/drives were the only way to accomplish this. Eventually, the first AC VFDs became available, but only once flux-vector technology was introduced on top models was 100% of the motors torque available across the speed range. Today, flux-vector is available even on the smallest VFDs.
Tiny VFDs with Expansive Features
Today’s entry-level VFDs now include many other high-end features, in addition to good build quality. There are many cases where OEMs, and even hobbyists, will find need the improved control, safety, and functionality provided by:
- Flux-vector control
- Safe torque off (STO)
- Single-phase input to three-phase output
- Sensorless vector control for increased torque at lower speeds
- Advanced networking/communications like EtherNet/IP and Modbus TCP
- On-board closed-loop PID control
- Integrated I/O
- A built-in PLC for logic control
Micro VFD Considerations
Because micro VFDs are so capable and economical, they should be considered for any application where there is even the slightest chance that motor speed may need to be adjusted, and even many applications where motor speed will not be varied. The cost can be comparable to that of a motor contactor and overload combo, and some versions are even available with NEMA 4X ratings, making them suitable for washdown areas.
Advantages for OEMs and Hobbyists
OEM machines often use PLCs and motor starters together, but in many cases a micro VFD can provide the functionality of each of these components, and it can also accept single-phase power while operating a three-phase motor. Many hobbyists today are automating second-hand equipment like lathes and grinders, and they’re finding micro VFDs are often the best solution.
Although basic small VFDs still exist, there are several compelling reasons for OEMs, hobbyists, and other end users to use newer and extremely capable micro VFDs. In many cases, these micro VFDs have benefited from the trickle-down effect.