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This paper presents a method for improving the control design for a high-power induction motor (IM) drive employing rotor-flux-based orientation. An offline genetic-algorithm routine is used to estimate the electrical and mechanical parameters of the machine using only speed transient measurements. This routine is applied to a range of operating conditions to obtain an accurate knowledge of the IM parameters as a function of the d-axis motor current [i.sub.d]. The information acquired is then employed, together with an enhanced control design obtained by optimizing speed and current transient responses, to increase the performance of the vector control algorithm. The effectiveness of this design method is demonstrated through a wide range of simulations using Matlab--Simulink and experimental results at power levels up to 230 kW. Index Terms--Genetic algorithms (GAs), induction motors (IMs), parameter estimation, rotor-flux control.

This paper looks at the requirements and challenges of designing a permanent-magnet (PM) motor for a directly driven electromechanical actuator for aerospace applications. Having a directly driven system, the intermediate gearbox is eliminated, bringing advantages in terms of lower component count and reduced jamming probability. The design of a low-speed high pole number PM motor will be investigated as a potential solution. The main goals of the design are a high level of actuator integration in order to minimize weight and volume, fault tolerance, and high reliability. The design will be tailored to the requirements of a typical midspoiler actuation system for a large civil aircraft. Index Terms--Aerospace actuation, electromechanical actuator (EMA), fault tolerance, permanent-magnet (PM) machines, sensorless.

A detailed magnetic reluctance-based computational model of an induction machine, into which a traditional rotor-flux-orientated vector control scheme has been grafted, is used to examine the influence of saturation of both main and leakage flux paths upon vector-controlled drive performance. Individual machine teeth, windings, and conductors are incorporated, as is pseudo-3-D modeling of skew. The cross-saturation effect is therefore determined from the basic dimensional and winding design data of the machine. Effective compensation methods can then be derived for practical implementation. Direct rotor flux orientation and magnitude control is used to ensure that inaccuracies in a machine-parameter-based vector control scheme are not reflected in the results for cross saturation. Results for a 15-kW four-pole induction motor with rotor skewed one stator slot pitch show that skew leakage flux is predominantly responsible for cross saturation. The skew leakage flux is shown to heavily saturate one end of the machine and to reduce the air gap flux density at the other. At 200% rated load current, this equates to an 11% reduction in direct axis flux if [i.sub.sd] is kept constant. To compensate for this reduction, a 27% increase in [i.sub.sd] would be required. Index Terms---Cross coupling, induction machines, skew, vector control.