‘World’s largest’ high-speed VFD

Source: PlantServices.com

Oct 16, 2008

Siemens Energy & Automation Inc. announced its Robicon Perfect Harmony Drives have reached a technical milestone with the introduction of a 8 MW variable-frequency drive (VFD) that operates with an output frequency of 500 Hz, making it the world’s largest high-speed VFD.

The drive is the latest in a series of high-speed Siemens drives. The basic VFD topologies have been limited to output frequencies in the 120 to 200 Hz range, but the company already has manufactured and installed drives that operate at frequencies between 315 Hz and 400 Hz.

The drive’s power cell-based multilevel topology allows operation up to 500 Hz, regardless of the VFD power rating. Tests on the VFD control were set to operate the motor in encoderless vector control with 920 Hz IGBT switching frequency, resulting in an effective switching frequency of 9.2 kHz and a sample frequency of 9.2 kHz. This test drive demonstrated very high-quality waveform to the motor with low harmonic distortion.

This latest VFD will be used to drive permanent-magnetic motors, such as those found in natural gas processing and transportation applications that require high-speed compression. Siemens is one of the few companies to design a VFD that can operate with these physically smaller, more efficient permanent-magnetic motors.

“Siemens has been an engineering pioneer for more than a century. This latest breakthrough demonstrates our commitment to developing new technologies to increase productivity and energy efficiency for our customers,” says Anne Cooney, vice president, Power Conversion Division, Siemens Energy & Automation (www.siemens.com/drives).