The design optimization of synchronous reluctance (SyR) machine and its extension to internal permanent magnet (IPM) motors for wide speed ranges is considered in this paper by means of a Finite Element Analysis-based multi-objective genetic algorithm (MOGA). The paper is focused on the rotor design, that is controversial key aspect of the design of high saliency SyR and IPM machines, due to the difficult modeling dominated by magnetic saturation. A three step procedure is presented, to obtain a starting SyR design with the optimal torque versus torque ripple compromise and then properly include PMs into the SyR geometry, given the desired constant power speed range of the final IPM machine. The designed rotors have been extensively analyzed by computer simulations and two SyR prototypes have been realized to demonstrate the feasibility of the design procedure.

This paper presents an automated procedure for coils conductors’ arrangement. The procedure has been applied to slotless permanent magnet machines having planar magnetic stator windings, such as printed circuit board (PCB) coils. The proposed method is driven by optimization techniques whose goal is to find a proper arrangement of PCB traces, which make up stator windings in order to find some trade-off solutions, optimal respect to some objective functions. A time-efficient numerical model has been developed to reduce computational load and thus make the optimization based design attractive. The paper shows results of numerical simulations of an annular permanent magnet synchronous machine having 200 poles and PCB windings.

Sensorless control of an axial flux permanent magnet motor drive is proposed and tested. The motor is not purposely designed for sensorless control and shows a very small inherent saliency. This significantly affects the saliency-based position estimation in the low speed region. Other non-idealities, such as the non-sinusoidal back-EMF waveforms and possible misalignment between stator and rotor make the control more challenging. A robust sensorless control scheme is proposed, able to deal with these non-idealities with a rather simple implementation. The position estimation is based on a closed loop hybrid observer of the permanent magnet flux linkage. Experimental results report torque and speed sensorless control.

Phase-locked loop (PLL) algorithms are commonly used to track sinusoidal components in currents and voltage signals in three-phase power systems. Despite the simplicity of those algorithms, problems arise when signals have variable frequency or amplitude, or are polluted with harmonic content and measurement noise, as can be found in aircraft ac power systems where the fundamental frequency can vary in the range 360-900 Hz. To improve the quality of phase and frequency estimates in such power systems, a novel PLL scheme based on a real-time implementation of the discrete Fourier transform (DFT) is presented in this paper. The DFT algorithm calculates the amplitudes of three consecutive components in the frequency domain. These components are used to determine an error signal which is minimized by a proportional-integral loop filter in order to estimate the fundamental frequency. The integral of the estimated frequency is the estimated phase of the fundamental component, and this is fed back to the DFT algorithm. The proposed algorithm can therefore be considered to be a PLL in which phase detection is performed via a DFT-based algorithm. A comparison has been made of the performances of a standard PLL and the proposed DFT-PLL using computer simulations and through experiments.

This paper describes the torque production capabilities of planar magnetics windings and presents an automated procedure for coils conductors’ arrangement. The procedure has been applied on an ironless axial flux slotless permanent magnet machines having planar magnetic stator windings, such as printed circuit board (PCB) coils. The proposed method is driven by optimization techniques whose goal is to find a proper arrangement of PCB traces, which make up stator windings, in order to find some trade-off solutions, optimal respect to the maximization of average torque and the minimization of torque ripple. A time-efficient numerical model has been developed to reduce computational load and thus make the optimization based design attractive.

The automatic design of synchronous reluctance (SyR) machines is considered in this paper by means of finite-element analysis and multiobjective optimization algorithms (MOOAs). The research focuses on the design of the rotor geometry, which is the key aspect of the SyR machine design. In particular, the performance of three popular MOOAs is analyzed and compared in terms of quality of the final design and computational time. A procedure to minimize the computational burden of the optimized design process is introduced and applied to a three-layer and a five layer rotor. Two prototypes experimentally demonstrate the feasibility of the design procedure.

The sensorless position control of permanent-magnet motors is successfully implemented by superimposing a high-frequency voltage signal on the voltage reference or adding a high-frequency current signal to the current reference. The former approach is usually preferred because of its simplicity, although the latter one may allow better performance. This paper presents a new algorithm for the sensorless control of low-saliency permanent-magnet synchronous motors based on high-frequency sinusoidal current signal injection into the d-axis. Different from the related literature, the position information is derived by analyzing the measured high-frequency currents. The amplitude of the d-axis voltage reference is also exploited to improve performance. A proportional-integral (PI) controller plus a resonant term (PI-RES) is adopted to ensure the accurate tracking of both the dc and high-frequency components of the d-axis current reference. The main advantages of the proposed approach are the increased accuracy and sensitivity with respect to the approach based on voltage injection, the insensitiveness to inverter non-linearities that are compensated by the current regulation loop, the actual control on the injected current value, and the practical absence of acoustic noise. Experiments on a linear tubular permanent-magnet synchronous motor prototype have been carried out to verify the aforementioned advantages. This paper also presents a discussion of the parameters of the PI-RES.

The sensorless position control of permanent-magnet (PM) synchronous motors can be successfully implemented by superimposing a high-frequency voltage signal on the control voltage. In this paper, the position estimation is obtained by means of a high-frequency sinusoidal voltage signal injected along the estimated d-axis. Several methods proposed in the literature obtain the position estimation by tracking the zero condition of the high-frequency q current component. We propose a new approach that also exploits the d-axis high-frequency current component and allows working with injected voltage signal of reduced amplitude, thus reducing noise and additional losses. The main contribution of this paper relies in the compensation of the motor end effects due to the finite length of the tubular motor armature. These effects must be taken into account in the motor modeling because they cause an error in the position estimation that varies with the motor position. The modeling of the phenomenon and a proper compensation technique are proposed in this paper. Last, a simplified integral-type controller is used to estimate motor position instead of the commonly adopted proportional-integral controller plus integrator, and this requires a low-effort design. Experiments on a linear tubular PM synchronous-motor prototype are presented to validate the theoretical analysis and evidence the feasibility of the proposed sensorless technique.

The paper reports some main results obtained within the project PON02_ 00576_3329762 “Sistemi avanzati mini-invasivi di diagnosi e radioterapia" AMIDERHA. The project goal is the optimization of a compact Linear Accelerator, operating at the frequency 3 GHz and accelerating the proton beam up-to the energy of 150MeV, such as the development of an innovative diagnostic equipment for proton therapy. The three project objectives are i) the design and optimization of the resonant cavities constituting the tanks of the Side Coupled LINAC; ii) the study and design of a magnetic field generator system for the diagnostic technique Magnetic Particle Imaging; iii) the development of integrated front-end electronics for GEM detectors.

This paper proposes the compact differential evolution (cDE) algorithm. cDE, like other compact evolutionary algorithms, does not process a population of solutions but its statistic description which evolves similarly to all the evolutionary algorithms. In addition, cDE employs the mutation and crossover typical of differential evolution (DE) thus reproducing its search logic. Unlike other compact evolutionary algorithms, in cDE, the survivor selection scheme of DE can be straightforwardly encoded. One important feature of the proposed cDE algorithm is the capability of efficiently performing an optimization process despite a limited memory requirement. This fact makes the cDE algorithm suitable for hardware contexts characterized by small computational power such as micro-controllers and commercial robots. In addition, due to its nature cDE uses an implicit randomization of the offspring generation which corrects and improves the DE search logic. An extensive numerical setup has been implemented in order to prove the viability of cDE and test its performance with respect to other modern compact evolutionary algorithms and state-of-the-art population-based DE algorithms. Test results show that cDE outperforms on a regular basis its corresponding population-based DE variant. Experiments have been repeated for four different mutation schemes. In addition cDE outperforms other modern compact algorithms and displays a competitive performance with respect to state-of-the-art population-based algorithms employing a DE logic. Finally, the cDE is applied to a challenging experimental case study regarding the on-line training of a nonlinear neural-network-based controller for a precise positioning system subject to changes of payload. The main peculiarity of this control application is that the control software is not implemented into a computer connected to the control system but directly on the micro-controller. Both numerical results on the test functions and experimental results on the real-world problem are very promising and allow us to think that cDE and future developments can be an efficient option for optimization in hardware environments characterized by limited memory.

Integration of control and measurement functionalities inside the power modules is a strategic research field for both the new industrial and renewable energy systems applications, such as reliability in harsh environments and compact design is extremely important for the aircraft and automotive sectors. The project aims at developing and validating new high-efficiency power modules (with embedded control functionalities) based on new semiconductor devices characterized by high power density, working at high frequencies and at high temperatures. The contribution of the Politecnico di Bari research group regards the design and construction of power converters demonstrators for aircraft, automotive, industrial and photovoltaic applications.

The project aims at developing and validating propulsion systems technologies for unmanned aerial vehicles (UAV) having long and high altitude missions. The focus of the project is a propulsion system based on a two-stroke diesel engine adopting a hybrid supercharging system to guarantee the target power in high altitude missions. The supercharging system includes standard turbo charger directly coupled with a high-speed electrical machine. Such a system can recover energy from the turbine or give energy to the compressor depending on the mission profile so to optimize overall system performances. A synchronous reluctance motor/generator capable of developing 5 kW at 50.000 rpm was developed in the Energy Factory Bari laboratory, a joint initiative of Politecnico di Bari and AVIO AERO.

This paper presents a study of the effects obtained when a portion of permanent magnet material is replaced by a soft magnetic composite piece over the rotor poles of an axial flux machine. This technical solution can be adopted to increase the machine inductance in order to limit short circuit currents or to increase the motor saliency and implement sensorless control schemes based on high frequency signal injection. Some design rules for the design of the soft magnetic poles have been derived in order to obtain the desired inductance and/or saliency. The analysis has been validated with finite element analisys and numerical simulations using Matlab/Simulink environment. Some preliminary experimental results have also been reported.