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The paper proposes a multiobjective optimization procedure for five-phase induction machines based on the NSGA-II (nondominated sorting genetic algorithm). In the optimization procedure, two objective functions are used (efficiency and cost of conductor material) along with 14 design variables, producing a large number of viable solutions. The design variables describe geometrical constraints, electrical and magnetic loading, and the waveshape of the airgap induction. The underlying analytical model of the machine includes the saturation of the iron parts and magnetic losses produced by higher space harmonic waves present in the airgap induction. The most relevant solutions regarding the objectives are validated through the finite element method, showing that the method proposed here is able to find practical solutions which represent a high efficiency, a reduced volume, or even a compromise between these objectives. [ABSTRACT FROM AUTHOR]

This paper proposes a new method to estimate the electrical parameters of five-phase induction motors based on the response to a step voltage applied to the stator with the rotor at standstill. The first part of the method consists of the identification of the parameters of the dynamic model expressed in terms of transfer functions including the fundamental and third-harmonic components of the airgap induction. The second part consists of an open-phase test proposed to estimate the stator leakage inductances of each circuit separately. Further, the impact of iron saturation on the parameters is discussed through Finite Element Analysis of a case study. The accuracy of the proposed method is experimentally assessed through the analysis of the behavior of a 4.5-kW motor running in a closed loop under Rotor Field-Oriented Control. The theoretical and practical results suggest that the method can also be applied to self-commissioned drives, given that the estimation proceeds under null torque and speed. The prominent advantages of the proposed method are (i) the possibility of tracking the saturation effects on the parameters, (ii) the tests are easy to execute, and (iii) few sensors are required. [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]