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 permanent magnet motor 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 Advantages of a Permanent Magnet Motor?
For similar power levels, a permanent magnet motor has higher power density per length, making it shorter and lighter than conventional ESP motors.
The advantages of a permanent magnet motor include better efficiency, higher power factor performance and compactness. On average, the permanent magnet motor uses 20 percent less power than the induction motor.
Permanent magnet motors need to be operated with a different type of control for variable speed drive and require matching transformers for high frequency applications.
What Are the Benefits to Operating an ESP with a Permanent Magnet Motor?
Russia’s oilfield has widely adapted the use of permanent magnet motors in ESP applications. It is very likely that the use of permanent magnet motors 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 permanent magnet motors 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 permanent magnet motors allows. This comes not only from a permanent magnet motor’s higher power density eliminating the need for tandem motors options but also a permanent magnet motor’s efficiency curve that allows a single motor to operate on a much wider operating range than an IM.
What Should You Look for When Selecting a Permanent Magnet Motor?
Depending on the project and objective, 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 permanent magnet motor 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.