Study of the Synchronous Reluctance Motor Design

Abstract

The paper focuses on studying the external-rotor synchronous reluctance motor. The analysis is performed to estimate the influence of the number of stator slots and non-magnetic areas in the rotor (i.e., flux barriers) on the electromagnetic torque and torque ripple of the studied motor. It is concluded that the increase in the number of stator slots Z = 6 to Z = 18 causes an approximately twofold decrease in the ripple factor, but torque increases by 5 %. Electromagnetic torque will be increased approximately by 24 %, if non-magnetic flux barriers are created in the rotor of the studied synchronous reluctance motor.

Design of Low-Torque-Ripple Synchronous Reluctance Motor with External Rotor

“…The following sizes of the motor under analysis are taken as constant: the outer diameter is 170 mm, the axial length of the motor active part is 100 mm, the anchor outer diameter is 100 mm and air gap is 0.5 mm. The results presented in [7] show that the effective number of stator slots for the motor with the accepted dimensions is Z = 18. Larger slot number is no desirable from the perspective of dental mechanical strength and winding creation.…”

“…According to the results obtained in paper [7], it has been concluded that after increasing the number of stator slots, torque ripple is substantially reduced, while an amplitude value of the fundamental harmonic of electromagnetic torque is slightly increased. Thus, increasing the number of stator slots from Z = 6 to Z = 18 leads to an approximately twofold decrease in the torque ripple factor and to an increase in the amplitude value of fundamental harmonic of electromagnetic torque by 5 %.…”

“…In order to increase electromagnetic torque of segment-shaped synchronous reluctance motor, studies [6]- [7] propose making an additional non-magnetic space in each segment of the rotor (see Fig. 2).…”

“…Results published in paper [7] show that torque ripple in the synchronous reluctance motor is strongly influenced by a number of stator slots and width of slot opening. According to the results obtained in paper [7], it has been concluded that after increasing the number of stator slots, torque ripple is substantially reduced, while an amplitude value of the fundamental harmonic of electromagnetic torque is slightly increased.…”

Comparison of Synchronous Reluctance Motors with the Outer and Inner Rotor

“…T 1max -the amplitude of the first harmonic of electromagnetic torque curve; 3. k p -the ripple factor. For calculation of ripple factor k p formula from [10] is used (2) where n is the number of evenly selected points on the half interval of the electromagnetic torque sinusoidal curve; Δa is the difference between values of the electromagnetic torque T em and the first harmonic of electromagnetic torque T em1 in relevant points; T max1 is the maximum of the first harmonic of electromagnetic torque. Table 2 and shown in Fig.…”