Reducing torque pulsations in PMa-SynRM: a way for improving motor performance

Abstract

This paper aims to evaluate the performance of synchronous reluctance motors assisted by a permanent magnet (PMa-SynRM) focused on efficiency and torque pulsations. PMa-SynRM shows high efficiency and power factor, compared to induction motors (IM), although they have a greater cost. These machines develop relatively high torque ripple, cogging torque, and torque imbalances. Consequently, the electromagnetic torque is reduced, the motor temperature is increased, and mechanical vibrations are induced. The optimal design of the machine structures such as flow barriers, permanent magnets, and stator slots, among others, allow reducing torque pulsations. A comparison is made between different designs of the PMa-SynRM reported in the scientific literature, and the effects on efficiency, torque pulsation, and operating costs are evaluated. A case study on the motor driving the air conditioner blower in a hotel room was made, to determine the best economic variant between IM or PMa-SynRM. A sensitive analysis was made to evaluate several uncertainties. The advantages of using one of the PMa-SynRM analyzed were demonstrated. Also, it was proved that the investment is feasible economically, although NPV and payback are not the best, due to low load factor in inverter-controlled motors in air conditioners.

An Effort to Replace Interior Permanent Magnets Rotors with Assisted Reluctance Rotors

“…The torque ripple is due to the interaction between spatial harmonics produced from the magnetomotive force in the stator and the air gap permeance. Cogging torque, on the other hand, occurs from the interaction between PM in the rotor and the stator slots [8]. It is not possible for all the orders of the harmonics to be eliminated or to be canceled out.…”

“…In bibliography it can been found different ways for reducing the torque ripple. One of them refers to selecting the appropriate number of flux barriers and stator slots [8]. In this case the angle of the side air cavities must be aligned with the stator's slots.…”

Determining the effect of stator groove geometry in a traction synchronous reluctance motor with permanent magnets on the saw-shaped electromagnetic moment level

“…To reduce a saw-shaped moment, it is possible to use semi-open grooves of the stator, which, on the one hand, reduce the uneven distribution of induction, and, on the other hand, provide an opportunity to comply with the conditions of technology for fabricating a stator winding. This approach is used in work [13], which examines the effect of the opening of the groove on the electromagnetic moment. The authors of the cited work note the significant impact of the groove shape on the energy indicators of the motor.…”

“…The authors of the cited work note the significant impact of the groove shape on the energy indicators of the motor. However, the approach considered in [13] refers to motors of relatively low power, with a loose stator winding, for which it is possible to use closed slots. The effect of the stator gearing for the stator's explicit pole winding is considered in work [14]; its significant impact on the nature of the electromagnetic motor moment is noted [15].…”

MATLAB/Simulink modeling of electric motors operating with harmonics and unbalance

“…On average, EMs consume approximately 53% of global electricity consumption and between 60-70% of electricity consumption in the industrial sector, representing 5.5 Gton of CO2eq emissions [1]- [3]. The EMs, since their creation in 1888 by Nikola Tesla, has been designed to operate with balanced sinusoidal voltages close to their nominal value; therefore, any deviation from the nominal voltage can cause problems in its operation [4]- [6] The most common steady-state power quality problems in distribution systems are voltage deviation, voltage unbalance, and harmonics. The voltage deviation is mainly produced by variations in the load and the incorrect selection of the connection point of the transformer (TAP) [7].…”