Introducing Analytical Formulas for Calculating Back EMF of the Contra-Rotating Double-Rotor Axial Flux Permanent Magnet Synchronous Machine

Abstract

Back electromagnetic force (back EMF) is one of the most significant performance characteristics of the machine which significantly affects the machine current, efficiency, power factor, and power angle. Studies showed that the precise analytical formulas to calculate the back EMF of Counter-rotating dual rotor axial flux permanent magnet synchronous machines (CRDR-AFPMSMs) were not presented so far. While by helping the analytical formulas, back EMF is calculated faster than the finite element method (FEM). Therefore, the novelty of this article is calculating the back EMF of CRDR-AFPMSMs considering its harmonic components. To fulfill this goal, Maxwell’s equations are used. The back EMF waveform obtained from the proposed formulas is compared with the results of FEM. Comparing the results confirms that the obtained results from the finite element (FE) simulation and analytical formulas are in good accordance. Besides, the shifting technique is used to reduce harmonic components of the back EMF. By helping proposed formulas and shifting techniques, the Total Harmonic Distortion (THD) of back EMF has decreased from 12.12 to 4.88%.

Keywords:

• axial flux permanent magnet machine
• back electromagnetic force (back EMF)
• counter-rotating
• dual rotors
• finite element method (FEM)

Additional information

Notes on contributors

Elham Rahimi Namaghi

Elham Rahimi Namaghi was born in Mashhad, Iran, in August 1988. She received the B.Sc. degree from the Birjand University, Birjand, Iran, in 2011. In addition, she received her M.Sc. degree from the Shahrood University of Technology, Shahrood, Iran, in 2016. She is currently a PhD student in Semnan University, Semnan, Iran. Her research interests include design, simulation, and control of electrical machines.

Hamid Reza Izadfar

Hamid Reza Izadfar is currently an Assistance Professor in the Electrical and Computer Engineering Department of Semnan University. His main research interests are the design and analytical and numerical analysis of electric machines and drives.