Search

The paper addresses the effects of high-order space harmonics on the steady-state performance of five-phase induction machines operating under unbalance. We show that the airgap harmonic fields with orders higher than three, although usually disregarded, can produce a significant increase in the torque pulsation and in the Joule losses. We propose a model based on symmetric components which is used to demonstrate that the field produced by each rotor harmonic current is related to two stator sequence currents. Further, the proposed model allows determining additional losses and harmonic torques produced by airgap harmonic fields with orders higher than three, which up to now have not been addressed elsewhere. As a case study, we applied the model to two five-phase induction machines with different designs and assessed the influence of high space harmonics under operation at steady state with one open phase in the stator. The model has been validated by comparing analytical results with results obtained through finite element analysis. Finally, the model validation was also based on experimental results obtained from tests with two prototypes under many different conditions. • We introduce a new model of five-phase induction machines including space harmonics. • The model describes the steady-state behavior of machines operating under fault. • The model allows estimating joule losses and torque pulsation due to space harmonics. • The validation of the model is based on fem analysis and experimental results. [ABSTRACT FROM AUTHOR]

This paper addresses the relation between some constructive parameters of five-phase induction machines and the airgap induction distribution under operation with one phase opened; we focus on the impact of design parameters on the airgap induction and the Joule losses. The influence of design parameters of the rotor and the stator is assessed using three distinct machines as a case study: two with identical stator but different rotors, and one with a distinct stator and also a distinct rotor. The results from the case study show that the characteristics of the stator windings, such as the number of slots per pole and phase and the number of layers, have less impact on the airgap induction under fault than under healthy operation. Besides, the case study shows that a decrease in the number of rotor bars contributes to an increase in the amplitude of the third harmonic component of the airgap induction. Finally, theoretical results are validated through analysis with the finite element method. [ABSTRACT FROM AUTHOR]

We propose a method to estimate all electrical parameters of five-phase induction motors based on a new concept of instantaneous impedance. Only stator voltages and currents acquired during no-load startup tests are required to determine the parameters of the fundamental and third-harmonic equivalent circuits. Additional quantities, such as rotor speed and electromagnetic torque, are also estimated from measurements. Unlike similar procedures, the parameters of the third-harmonic circuit are estimated separately from the parameters of the fundamental circuit, thus making the estimation more accurate. To experimentally validate the method, we tested a 4.5-kW and a 5.5-kW prototype using sinusoidal as well as trapezoidal voltages generated by a static converter. One of the main advantages of the proposed procedure is the possibility of using data acquired also with a static converter. Besides, to validate the method as well as to assess the accuracy of the estimated parameters, we first simulated the machine behavior using the estimated parameters and the measured stator voltages as input and subsequently compared the simulated currents with those acquired during no-load startup and load tests. Furthermore, we implemented a closed-loop Rotor Field Oriented Control (RFOC) scheme using both calculated and estimated parameters and then compared the controller performance with both sets of parameters. The practical results demonstrate not only that the method provides accurate estimates for all parameters but also that the use of the estimated parameters can improve the performance of the controller. [ABSTRACT FROM AUTHOR]