Effects of high-order space harmonics on the operation of five-phase induction machines under unbalance.

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.

Performance estimation of three-phase induction motors from no-load startup test without speed acquisition.

This paper presents a simple method to estimate the steady-state performance of three-phase induction motors using only measurements of stator voltages and currents, acquired during a no-load startup test and without speed acquisition. The procedure consists of two steps: (a) firstly, the parameters of the single-cage model are estimated while considering the rotor resistance and the leakage inductances variable with the slip; and (b) secondly, the steady-state performance is estimated from the equivalent circuit using the estimated parameters. The proposed method is experimentally validated through tests involving 229 medium-power motors with power ranging from 22 to 90 kW; the estimated performance is then compared with measurements obtained through standardized laboratory tests.

Induction distribution of five-phase induction machines under open-phase fault.

The main objective of the paper is to determine the induction distribution of five-phase induction machines operating under unbalanced steady state, focusing on the operation with two opened stator phases. Firstly, we present an analytical model based on symmetric components which includes the third harmonic component of the airgap induction. The model is then used to determine the induction distribution in the airgap and also in the main iron parts, i.

The generalized forced oscillation method for tuning PID controllers.

In this paper a generalized tuning methodology for proportional-integral-derivative (PID) controllers is proposed. The methodology is akin to the Ziegler-Nichols forced oscillation method, inheriting fully its practical appeal, but can be applied to much more general classes of plants. This generalization is achieved by employing a relay with adjustable phase (RAP) in a relay feedback experiment, and the tuning consists of formulas based on measurements obtained from this experiment.