[aeroscott]

Industrial applications

Apparently the motor company's and schools never considered telling engineers they could run the vfd/ motor over 60 cycles , say 100 cycles.
The advantages are 2X power and a wider torque range (with 2X gearing ),
" enhance gearmotor performance significantly by increasing stability , by reducing inertia mismatch,widening the available speed range,eliminating motor overheating at low speeds, and enabling the use of smaller motors"
They are not talking about 200,300 or 400 hz.
This was in Machine Design , May,2018
I think this lac of understanding hindered the EV movement greatly.

 

[brian_]

Industrial applications

Apparently the motor company's and schools never considered telling engineers they could run the vfd/ motor over 60 cycles , say 100 cycles.

That's not true. VFDs were running motors at over the utility line frequency at least 25 years ago in a heavy industrial applications. I worked for a company which operated them, running motors up to 3.7 MW (nominal, that is, at 60 Hz... so more power when at higher speed). The ratio of operating frequency to nominal frequency wasn't high in this particular case, for at least two reasons:

1. proven existing mechanical components (including the motors) were being used, and
2. motors were configured to run from the VFD or directly across the line, so they needed to be usefully functional at line frequency.

Was the quote from this article?

Achieve Better System Stability & Wider Speed Range​

That's an advertisement, so I didn't download the content (a "whitepaper") to check.

 

[steveob]

well, it is erroneous to imply that the article is representative of "VFD enginners".

http://www.machinedesign.com/may-2018#54

given how important efficiency is to cost in an industrial setting, I'm surprised they didn't cover it, and most of these motors were designed with 50/60hz in mind.