VFD Technology for Running High Speed Gearless Turbo Blowers

At KEB, we thrive on challenging applications where our advanced technology and deep application engineering expertise truly differentiate us.

From complex multi-axis coordinated motion control to systems operating in extreme environmental conditions, we’re dedicated to solving the toughest drive challenges. A prime example of this is the demanding realm of high-speed motor/generator operation, particularly in gearless turbo blowers.

KEB boasts extensive experience in optimizing the performance of these critical high-speed systems. This post will outline the most important factors to consider when selecting VFD technology for running high-speed gearless turbo blowers and explain why KEB’s F6 VFD offering makes us the partner of choice for leading turbo blower manufacturers worldwide.

High-Speed VFDs

When we refer to “high-speed” in the context of VFDs, we’re talking about a very specific and demanding operational range. The most widely accepted definition, as outlined by the U.S. Department of Commerce in regulation ECCN 3A225, classifies drives operating at 600Hz and above as high-speed.

These applications are incredibly demanding on VFDs, requiring exceptionally stable motor control algorithms and ultra-fast control loops. Think of it like skateboarding:

I can easily stand still on a skateboard, or even move slowly, maintaining good control and correcting for minor obstacles like cracks. This is analogous to a standard, low-speed VFD application, where the drive has ample time to control the motor and compensate for dynamic load changes.

High-speed applications allow less room for error

However, imagine trying to skateboard at breakneck speed. Every tiny bump or shift in balance becomes a critical challenge. This is precisely the scenario with high-speed VFD applications – the control system must react almost instantaneously and with extreme precision to maintain stability and performance.

A company does not develop high-speed motor control algorithms overnight. KEB’s high-speed drive products represent decades of motor control engineering. And that is evident in the over 100,000 high-speed applications that are running in the field across a wide variety of power ranges and motor types.

Dedicated High-Speed Power Stages

The VFD power stages used in high-speed applications are also unique, especially at high power (200Hp+). The IGBTs must be capable of switching at a very high frequency – usually 8kHz or 16kHz. The higher switching frequency causes more heating and the power stages must be designed specifically for that use.

 
Air cooling these large IGBTs with high frequency can be challenging if not impossible. KEB also offers liquid-cooled drives which are particularly effective at cooling the large high-speed VFDs.

3C3 Protection for Corrosive Gases

In the wastewater industry, some high-speed blower applications face significant challenges from corrosive gases, especially in high-humidity environments. Gases like chlorine, ammonia, and hydrogen sulfide can severely damage VFD components and connections, leading to premature failure. KEB has developed a special protective board coating to combat these harsh conditions, specifically designed to meet IEC/EN 60721-3-3 class 3C2 standards, ensuring enhanced drive longevity and reliability.

KEB F5 3C3 Part Numbers

• 19F5E0R-Y0F4
• 20F5E0R-Z04F
• 21F5E0R-Z04F
• 22F5E0R-Y04F
• 23F5E0U-Z04F
• 26F5E0U-Y04D
• 28F5E0U-Y04H
• 28F5E0U-Y04D
• 29F5E0W-Y04H
• 29F5E0W-Y04D
• 30F5E0W-Y04D
• 30F5E0W-Y04H
• 32F5E0P-Y04H
• 33F5E0P-Y04H

Commercial Drives vs. R&D Drives

A key advantage for our customers is KEB’s proven track record and the fact that our high-speed drives are part of our standard F5 and F6 product lines. Unlike some high-speed drives that are more akin to R&D projects lacking proper certification or documentation, KEB’s offerings are fully UL-listed with comprehensive, up-to-date documentation. This significantly simplifies the installation and ongoing support of the final blower product.

Filter Technology

A critical part of KEB’s drive offering is our compliment filter technology. KEB offers a variety of different filters that include Harmonic Filters, EMI filters, and Sinewave filters. Harmonic filters can be used in Blower applications if IEEE 519 requirements need to be met.

 
Sinewave filters can be very advantageous to the motor-drive combination because they deliver a near-perfect sinusoid waveform to the motor which reduces motor heating and ultimately allows the motor to output more usable power.

Conclusion

Because KEB engineers both the filter and drive technology, we’ve become a crucial solution partner—not just a component supplier. This integrated expertise is best demonstrated by our ability to conduct powerful control simulations that accurately predict the performance of the filter-VFD-motor system.

 
The screenshot above shows hardware in the loop simulations. This offering dramatically reduces development time, often providing insights in minutes that would otherwise take months of iterative physical testing.

Have a high-speed turbo or compressor application you’d like to discuss? Connect with a KEB application engineer today to explore how we can help.