• norsk
    • English
  • English 
    • norsk
    • English
  • Login
View Item 
  •   Home
  • Fakultet for informasjonsteknologi og elektroteknikk (IE)
  • Institutt for elkraftteknikk
  • View Item
  •   Home
  • Fakultet for informasjonsteknologi og elektroteknikk (IE)
  • Institutt for elkraftteknikk
  • View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.

Design and Modelling of Linear Permanent Magnet Actuator with Gas Springs for Offshore Applications

Ummaneni, Ravindra Babu
Doctoral thesis
View/Open
Fulltext not available (Locked)
URI
http://hdl.handle.net/11250/2393096
Date
2016
Metadata
Show full item record
Collections
  • Institutt for elkraftteknikk [1941]
Abstract
Although rotary steerable systems have been evolving rapidly and delivering

unprecedented rates of drilling penetration, drillers nevertheless seek technologies that

further accelerate the drilling process. Currently, most down-hole motors with rotating

drill bits are driven by positive displacement motors and down-hole turbine motors. These

motors are classified depending on the type of power sections that are used to convert the

hydraulic energy of high pressure fluids to mechanical energy in the form of torque

output. In these designs, the power is transmitted from the power section to the drill bit

through different mechanical arrangements, such as drive shafts, coupling assemblies,

bearings, etc. During the transmission process, part of the developed torque is wasted,

which reduces the efficiency. In addition, bearing stresses limit the transfer of possible

forces to the drill bit. We proposed a novel concept to overcome these difficulties.

The proposed concept is unique because of the combination of a linear electrical machine

and gas springs. These gas springs allow the piston of the linear electrical machine to

oscillate at different frequencies depending on the required load conditions. The

characteristics of the high energy gas springs provide the opportunity to oscillate heavier

piston with longer stroke lengths. A large electromagnetic force from permanent magnets

and coils, in combination with gas springs, creates a high power linear electric actuator.

The oscillating heavy piston causes a considerable vibration in the housing, which is

utilized in the drilling application. The load can then be attached directly to the housing

and the machine can be made hermitically sealed, which eliminates leakage problems.

These features make the actuator suitable as a hammer in oil drilling applications.

A linear permanent magnet actuator (oscillomotor) is an energy conversion device that

integrates a linear permanent magnet (PM) machine and gas springs into a single unit.

My research work mainly addresses the design criteria, analytical and finite element

method (FEM) design calculations and dynamic analysis of the linear permanent magnet

actuator with gas springs. The selection of a suitable linear PM machine configuration is

very important to achieve the required demands, such as a compact diameter size, easy integration of gas springs, reduced losses to reduce heat generation, robustness, less

maintenance and higher force from the starting position. Different linear PM machine

configurations, such as flat, double flat, tubular longitudinal and transverse flux, are

discussed for drilling applications. The tubular longitudinal flux configuration is selected

as the most promising for drilling applications. This study analyses the selection of

different mover configurations and different magnet patterns. Design parameters such as

pole pitch, magnet width, stator inner diameter and air gap size are optimized based on

the analytical analysis of force characteristics. The complete design process of the linear

machine is discussed. Dynamic models of the linear actuator are developed.

Three prototypes of the linear actuator are built to verify the novel concept and validate

the force characteristics and dynamic modelling. The Force characteristics of the

prototype I is verified with the FEM simulated results. Impact tests are carried out using

prototype III. The test results shows the power input required at resonance is very low

compared to the other frequencies. The impact force per amp at resonance is 9.26kN. The

possibility of producing these higher power impacts at resonance, suitable for hard rock

drilling. Drill test is carried out using prototype II. The Effect of feed force on the dynamic

behaviour is discussed. The rate of penetration with different resonant frequencies and

different weight on bits are discussed.

This study also focuses on the suitability of this novel concept in other offshore

applications, such as wireline jar applications and ocean wave power generation.

Henceforth, this thesis describes the concept of the conversion of the movement of a float

in a wave power plant, which is characterized by high force and low speed energy, to a

high speed and low force energy in a linear generator by using gas springs. The simulation

model shows that an oscillating piston that is supported by gas springs and is compressed

and decompressed by a wave can convert more kinetic energy per volume from the float

to a secondary piston compared to a secondary piston that is simply attached to the float.

This model has not yet been validated with experimental work. According to the

simulation results, the size of the generator can be reduced by a factor of 12 for the same

power output compared to a buoy-connected piston.
Publisher
NTNU
Series
Doctoral thesis at NTNU;2016:130

Contact Us | Send Feedback

Privacy policy
DSpace software copyright © 2002-2019  DuraSpace

Service from  Unit
 

 

Browse

ArchiveCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsDocument TypesJournalsThis CollectionBy Issue DateAuthorsTitlesSubjectsDocument TypesJournals

My Account

Login

Statistics

View Usage Statistics

Contact Us | Send Feedback

Privacy policy
DSpace software copyright © 2002-2019  DuraSpace

Service from  Unit