8MW high-speed drive is `world’s largest`
Siemens claims to have produced the world’s largest high-speed variable speed drive – an 8MW system with an output frequency of 500Hz. It says it has developed a "unique" multi-level powercell topology that allows drives to be operated at up to 500Hz, regardless of the power rating. Conventional VSD topologies are limited to output frequencies in the range 120–200Hz.
The new VSD is designed to drive permanent magnet motors, such as those used in high-speed compressors for natural gas processing and transportation applications.
In tests, the VSD controls were set to operate a motor in encoderless vector control mode using a 920Hz IGBT switching frequency, resulting in effective switching and sampling frequencies of 9.2kHz. The test drive is said to have delivered a high-quality waveform to the motor with low harmonic distortion.
The Perfect Harmony drive has been developed at Siemens’ Robicon operation in the US, which it acquired in 2005.
