Induction Versus Permanent Magnet Motors for ESP Applications

Abstract

Abstract This paper provides an overview comparing Induction Motors (IM) and Permanent Magnet Motors (PMM) for Electric Submersible Pump (ESP) applications. What are the design differences and how the performances of the two types of motors are stacked against each other? What are the advantage and unique applications of PMMs? Why and how are PMMs controlled differently from IMs? Are there safety aspects that field engineers need to be aware of with PMMs? These questions will be addressed in the paper. The information presented includes literature review and latest R&D results. It covers operating principles of IM and PMM, selection of permanent magnet materials, operating frequency, stator windings and magnetic poles. PMMs offer better efficiency, higher power factor performance and compactness. Ideal applications include slim well applications, through-tubing rigless deployment, Y-tool completion and Electric Submersible Progressive cavity Pump (ESPCP). The paper will also shed some light on why conventional IMs cannot be used to drive ESPCPs directly without speed reduction gearboxes. It is very likely that the use of PMM will increase for ESP applications in the near future and this will require engineers to acquire a basic understanding of this technology. A high level comparison between IM and PMM is missing in the ESP industry and this paper fills the gap. 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.