A permanent magnet motor (PMM) is a type of brushless electric motor that uses permanent magnets attached to the rotor, maintaining the electromagnetically powered stator. A PMM is more economical, with greater energy efficiency, reduced electrical losses, lower operating current and less heat generation than a conventional induction motor (IM) of the same horsepower rating.
What are the benefits of a PMM?
For similar power levels, a PMM has higher power density per length, making it shorter and lighter than conventional ESP motors.
PMMs offer better efficiency, higher power factor performance and compactness. On average the permanent magnet motor uses 20% less power than the induction motor.
PMMs need to be operated with a different type of control for variable speed drive (VSD) and require matching transformers for high frequency applications. The paper also intends to highlight the safety aspects of PMMs in shop and field handling.
What are the benefits to operating an ESP with PMM?
Russia’s oilfield has widely adapted the use of PMMs in ESP applications. It is very likely that the use of PMM for ESP applications will expand further in the near future, requiring organizations to expand their understanding of this technology. Apart from standard applications targeting lowering energy consumption related to lifting, other applications include slim well applications, through-tubing rigless deployment, Y-tool completion and Electric Submersible Progressive Cavity Pump (ESPCP) without speed reduction gearboxes.
Almost all PMMs in the industry today require a different type of control for variable speed drive (VSD) and matching transformers. The variable speed control allows for a smooth adjustment to changing well conditions and softer startups for unconsolidated formations and other critical operating needs, allowing a better well optimization with an improved run life
A benefit that ESP users and suppliers have not yet fully understood or capitalized on a full motor rationalization that adopting PMMs allows. This comes not only from a PMM’s higher power density eliminating the need for tandem motors options, but also a PMM’s efficiency curve that allows a single motor to operate on a much wider operating range than an IM.
What to look for when selecting a PMM?
Depending on the project and objective, PMM selection should be based on efficiency power gains or specific to the application, in particular if this relates to a thru-tubing retrievable ESP. AccessESP is the only company in the market that has developed and commercialized a winning PMM that allows changing out an ESP with slickline and has provided improved efficiency, performance and equipment rationalization for a significant drop on inventory need and value.