14th International Conference on Optimization of
Electrical and Electronic Equipment OPTIM 2014
May 22-24, 2014, Brasov, Romania
A novel design of stator Ferrite PM single phase doubly salient small motor: FEM
characterization and controlled dynamics
A. S. Isfanuti1, L. N. Tutelea1, IEEE Member, F.J. H. Kalluf2, I. Boldea1, IEEE Life Fellow
1
University Politehnica of Timisoara, Romania,
2
Dept. of Technology and Development, EMBRACO S.A., Joinville, Brazil
Abstract
The present paper introduces a novel two coil 1 phase stator Ferrite PM motor [1]. The main targets are reduced material and
fabrication costs in a robust topology at 90% efficiency for a 35 W, 1600 rpm case study. Due to complicated flux lines (with
tapered airgap for self-starting) and magnetic saturation, direct FEM characterization (preliminary design) was applied.
The novel 1 phase stator Ferrite motor (Fig. 1) stems from the flux reversal (or flux switching) principles [2] and consists of
a two pole stator having the corresponding two coils in series, fed with a trapezoidal alternating current, assisted by four magnet
pieces and an isotropic four pole pair rotor. It comes as an alternative solution for an existing 3 phase 6 slot/4 pole Ferrite BLAC,
its main advantages being a simplified manufacturing process (lower manufacturing cost) and control. The target applications
consists of small power drives such as pumps and compressors. A preliminary design of 1 phase motor is performed, which makes
use of FEM in order to maximize the emf, the torque and minimise the cogging torque peaks within the critical rotor positions. An
extended FEM analysis follows on the resulted motor geometry, which covers emf, cogging torque, electromagnetic torque and
iron losses. Finally, the electric parameters, material cost and efficiency are determined. From the comparison with the existing
solution results a 20% reduction in initial manufacturing cost at the cost of 4% decrease in electric efficiency (from 94% to 90%).
However this should be compensated by motor cost and inverter control.
Two control solutions are proposed and simulated in order to verify the motor capability of producing the FEM predicted torque
(0.2 N). A Matlab Simulink dynamic model of the 1 phase motor is build (Fig. 2. a), which uses FEM imposed emf, cogging
torque and inductance versus position. First case study uses an open loop (V/f) control to drive the motor up to rated speed and full
load within 0.4 s. The second control strategy represents a close loop speed and current control (Fig. 2. b) which also proves the
motor capability of producing the required torque.
a)
c)
b)
Fig. 1 1 phase motor geometry a), flux paths for two representative positions b) and c)
b)
a)
Fig. 2 Dynamic Matlab Simulink model of 1phase motor [3] a), and close loop speed and current regulators b)
References
[1] F. Kalluf, I. Boldea, “Motor elétrico de relutância chaveado”, Brasilian Patent Ref: BR102013018363.6//July 18, 2013.
[2] R. P. Deodhar, S. andersson, I. Boldea, T. J. E. Miller, “The flux-reversal machine, a new brushless doubly-salient
permanent-magnet machine”, Trans. on Industry Applications, vol. 33, no. 4, July/August 1997, pp. 925-934.
[3] L, I. Iepure. “Sensorless control of single phase PM brushless dc motor drives” Ph.D. dissertation, Politehnica University
of Timisoara, Timisoara, 2010.
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