Control of subsea motors on multi-km cable lengths by Variable Frequency Drives

Oil & Gas exploration is now moving to increasingly extreme conditions such as ultra deep water which presents a major challenge to the industry. Offshore located Variable Frequency Drives are commonly used to start and operate pumps and compressors providing process optimization. Deep water and remote locations require very long cable step-outs to supply power to the subsea electric motors. Therefore drive solutions with nearly sinusoidal output current and voltage waveforms are needed. In addition to this characteristic multi cell topologies offer the benefit of high switching frequencies and therefore small filter designs. In addition to the well known H-bridge design the M2C topology is shown. New concepts for multi motor applications are possible because of the special electrical properties of this new topology.