Athanasios G. Sarigiannidis

Induction Motors Versus Permanent-Magnet Actuators for Aerospace Applications

This paper introduces a comparative study on the design of aerospace actuators concerning induction motor and permanent-magnet motor technologies. In the analysis undertaken, the two candidate configurations are evaluated in terms of both their electromagnetic and thermal behaviors in a combined manner. On a first step, the basic dimensioning of the actuators and their fundamental operational characteristics are determined via a time-stepping finite-element analysis. The consideration of the thermal robustness of the proposed motor configurations is integrated in the design procedure through the appropriate handling of their respective constraints. As a result, all comparisons are carried out on a common thermal evacuation basis. On a second step, a single objective optimization procedure is employed, considering several performance and efficiency indexes using appropriate weights. Manufacturing and construction-related costs for both investigated topologies are considered by employing specific penalty functions. The impact of the utilized materials is also examined. The resultant motor designs have been validated through manufactured prototypes, illustrating their suitability for aerospace actuation.

Multiobjective Evolutionary Optimization of a Surface Mounted PM Actuator With Fractional Slot Winding for Aerospace Applications

Overall optimization of electromechanical aerospace actuators requires a multiobjective analysis to account for both performance and efficiency, while considering technical costs, due to the conflicting nature of the respective criteria. This paper introduces a particular multiobjective, population-based optimization methodology, using the differential evolution algorithm combined with manufacturing cost and motor-clean-interface related constraints. A magnetic equivalent circuit model is implemented and integrated in the process to account for flux leakage effects. The methodology presents stable convergence characteristics and has been applied to further extend previous work regarding the optimization of a fractional slot concentrated winding surface mounted permanent magnet motor. The resultant motor design has been validated through a prototype and experimental results illustrated its suitability for aerospace actuation.

Switching Frequency Impact on Permanent Magnet Motors Drive System for Electric Actuation Applications

This paper investigates the harmonic losses and torque ripple of a surface permanent magnet (SPM) motor driven by pulsewidth-modulated inverter for a wide range of switching frequencies (SFs), using a 2-D nonlinear time stepping finite-element model, including strand conductors proximity effect, coupled with an appropriate external electric circuit. Such a method enables the estimation of torque ripple as well as the accurate prediction of the eddy current losses in the windings, lamination core, and PMs, respectively. Moreover, the total power losses of the inverter are calculated via analytical techniques. The analysis undertaken proposes an optimum SF, in terms of overall drive system efficiency and torque quality, considering multiple operating conditions. The simulated results are validated by measurements on a prototype SPM actuator, illustrating that the SF plays an important role on SPM motor drive applications.

Exploiting shaft generators to improve ship efficiency

Shaft generator (SG) systems have been exploited for long due to several appealing advantages they present. This type of generators is installed at the shaft of the main propulsion diesel engine while they are capable of operating as propulsion engine boosting devices if suitable power electronics are used. In this paper an effort is made to provide a comprehensive analysis of shaft generator role in ship power system efficiency improvement in relation with ship operation optimization point of view. Special reference is made to the interdependence of SG with power management system as they alter the operation point of both propulsion engine and the electrical generators affecting the optimal operating point.

Fast Adaptive Evolutionary PM Traction Motor Optimization Based on Electric Vehicle Drive Cycle

This paper introduces an evolutionary optimization procedure for the design of permanent-magnet motors (PMMs) for electric vehicle (EV) applications, considering a specific drive cycle with multiple operating points. For the purposes of the analysis, the New European Drive Cycle (NEDC) has been employed with two alternative PMM configurations. Energy distribution over the NEDC for a small passengers EV has been calculated and the equivalent multiple operating points have been extracted, using appropriate weights, in order to maintain an equal energy consumption basis, resulting in reduced computational cost. The proposed optimization technique is constituted of an adaptive differential evolution (DE) algorithm involving dynamic variation of the mutation factor, combined with finite-element (FE) and circuit models. The procedure is based on the precise calculation of the two axes input current components for each candidate solution and operating condition. The methodology introduced presents stable and fast convergence characteristics and has been applied to optimize the geometry of both surface-mounted and interior PMM configurations. The proposed motor is based on the thorough tradeoff among the two alternative optimized geometries and has been validated through measurements on a prototype.

Performance evaluation and thermal analysis of interior permanent magnet traction motor over a wide load range

This paper investigates the electromagnetic and thermal behavior of a Double Layer Interior Permanent Magnet Motor (DLIPMM) over a wide load and speed range for an Electric Vehicle (EV) application. The DLIPMM is simulated via a transient 2D Finite Element (FE) model, allowing for the accurate mapping of the motors main performance indexes. Simulations are performed for armature currents ranging from zero up to two times the nominal for all possible current phase angles and the torque and efficiency versus speed curves for a wide load range are extracted. The Maximum Torque per Ampere (MTPA) control for the Constant Torque Region (CTR) is employed, provided that the voltage constraints are not violated. For the Constant Power Region (CPR) a specific Field Weakening (FW) strategy is utilized in order to achieve an efficient motor drive. In a next step, a transient thermal FE model for the DLIPMM over a reference EV drive cycle and under abrupt overload condition is employed, in order to investigate the motor thermal robustness. The results demonstrate the benefits of the designed DLIPMM configuration, in terms of performance, efficiency, overload capability and thermal robustness.

Fault Tolerant Design of Fractional Slot Winding Permanent Magnet Aerospace Actuator

This paper introduces a particular permanent magnet motor (PMM) design methodology, considering advanced magnetic material characteristics, for aerospace actuator applications. In this class of problems, increased electromagnetic power density, fault tolerance, and high-temperature withstand properties are of major importance, and favored single-layer (SL) and double-layer (DL) fractional slot concentrated winding (FSCW) optimal topologies with different motor segmentation strategies have been compared. Under such strict nature of specifications, both operational and spatial, the implementation of advanced magnetic materials, particularly Vacoflux50 cobalt iron laminations and NMX-S43SH neodymium PMs, offer great services. The optimization methodology introduced is based on composite cost and penalty functions involving performance, efficiency, reliability, weight, and thermal criteria for multioperational behavior under normal and temporary overload conditions. An appropriate particle swarm optimization algorithm ensures fast convergence of the optimization variables. The resulting optimal SL and DL FSCW PMM configurations present certain complementary advantages, while the former one offering greater efficiency, thermal robustness, and physical segregation of the two motor parts is favored for this class of applications. Finally, the proposed motor configuration has been validated through measurements on a manufactured prototype.

Performance evaluation of MPPT techniques for PV array incorporated into Electric Vehicle roof

This paper deals with the implementation of a fast, fully integrated Maximum Power Point Tracking (MPPT) algorithm, in order to efficiently control a Photovoltaic (PV) system incorporated into a battery-Electric Vehicle (EV) roof. Major challenges for such PV systems are the rapidly changing irradiance conditions and partial shading of the PV cells. Perturb & Observe (P&O) as well as Incremental Conductance (INC)-based MPPT techniques, employing fixed and adaptive voltage steps, are developed and quantitatively assessed in terms of stability and fast transient response, via convenient dynamic simulation analysis. MPPT algorithm behavior over partial shading conditions is also investigated. In addition, the energy production as well as the enhancement in EV driving autonomy, in yearly basis, for the proposed PV system employing the optimal MPPT technique is computed, utilizing measured solar irradiance data and realistic driving scenaria.

Comparison of in-wheel permanent magnet motors for electric traction

This paper undertakes a comparative study between two different in-wheel Surface Mounted Permanent Magnet motors with Fractional Slot Concentrated Winding configurations designed for a light electric vehicle application. For the design of both motors two different approaches are followed, regarding the winding configuration and the relative dimensions of the motor, i.e. axial length and air-gap diameter, and additionally two alternative strategies are adopted concerning the selection of the reference operational point. The first motor comprises a double layer concentrated winding with all teeth wound while is slightly over-dimensioned increasing efficiency during overload operation. A single layer concentrated winding with alternate teeth wound and unequal teeth distribution is adopted for the second motor dimensioned in terms of weight minimization considering the nominal load operation. For the optimization of the first alternative, Taguchis method is utilized, while for the latter one a Strength Pareto Evolutionary Algorithm variant is developed. Both performances are validated by examining manufactured prototypes under real conditions.

Multi-operating points PM motor design methodology for electric actuation systems

In this paper, a comparative optimal design of Permanent Magnet Motors (PMMs) for aerospace actuation applications based on single and double layer Fractional Slot Concentrated Winding (FSCW) topologies with different motor segmentation strategies is undertaken, by means of a combined electromagnetic, fault tolerance and thermal evaluation. Initially, analytical machine equations and 2D Finite Element (FE) analysis are employed for the determination of the motors basic dimensional and operating characteristics. Both configurations considered are in a next step optimized regarding the mean torque, efficiency, torque ripple, induced Electromotive Force (EMF) quality and motor weight. The proposed methodology involves appropriate handling of mean torque and induced EMF as constraints through the application of a particular single-objective Particle Swarm Optimization (PSO) technique accounting also for multiple motor operating conditions. Fault tolerance and thermal robustness of the optimized motors are also examined. Both single layer and double layer FSCW PMM optimal configurations present complementary advantages for this class of applications.