Sensorless control of a dual-airgap axial flux permanent magnet machine for flywheel energy storage system

• Published in: IET electric power applications Vol. 7; no. 2; pp. 140 - 149
• Main Authors: Nguyen, Trong Duy, Foo, Gilbert
• Format: Journal Article
• Language: English
• Published: London The Institution of Engineering and Technology 01.02.2013; Institution of Engineering and Technology; The Institution of Engineering & Technology
• Subjects: AFPM machine; angular velocity control; Applied sciences; axial levitation force; Control systems; Direct energy conversion and energy accumulation; displacement control; dual‐airgap axial flux permanent magnet machine; Electrical engineering. Electrical power engineering; Electrical machines; Electrical power engineering; electromagnetic torque; Encoders; Energy accumulation; Energy storage; Exact sciences and technology; FESS application; Flux; flywheel energy storage system; Flywheels; machine windings; magnetic flux; magnetic levitation; Miscellaneous; Observers; permanent magnet machines; Permanent magnets; power converter; power convertors; Power electronics, power supplies; prototype machine; Regulation and control; rotary encoder; sensorless control; sensorless machine control; speed sensorless observer; three‐phase stator winding; vertical bearing stress; Weight reduction; magnetic flux; flywheel energy storage system; electromagnetic torque; power convertors; sensorless control; flywheels; sensorless machine control; angular velocity control; magnetic levitation; dual-airgap axial flux permanent magnet machine; AFPM machine; three-phase stator winding; FESS application; prototype machine; power converter; rotary encoder; energy storage; speed sensorless observer; displacement control; permanent magnet machines; machine windings; observers; axial levitation force; vertical bearing stress; Performance evaluation; Power converter; Costs; Stator; Sensorless control; Levitation; Bearing(mechanics); Power electronics; Energy storage system; Three phase winding; Optimization; Electromagnetic coupling; Angular measurement; Kinetic energy storage; Power control; Vector control; Speed regulation; Observer; Air gap; Controllability; Permanent magnet machine; Axial field
• ISSN: 1751-8660; 1751-8679; 1751-8679
• DOI: 10.1049/iet-epa.2012.0048

This study presents the sensorless vector control of a dual-airgap axial flux permanent magnet (AFPM) machine optimised for use in flywheel energy storage system (FESS) applications. The proposed AFPM machine has two sets of three-phase stator windings but only requires a single power converter to control both electromagnetic torque and axial levitation force. The proper controllability of the latter is crucial as it can be utilised to minimise the vertical bearing stress to improve the efficiency of the FESS. The method for controlling the speed and axial displacement of the machine is discussed. An inherent speed sensorless observer is also proposed for speed estimation. The proposed observer eliminates the rotary encoder, which in turn reduces the overall weight and cost of the system while improving its reliability. The effectiveness of the proposed control scheme has been verified by simulations and experiments on a prototype machine.