V. Delli Colli

Design of Axial Flux PM Synchronous Machines Through 3-D Coupled Electromagnetic Thermal and Fluid-Dynamical Finite-Element Analysis

This paper investigates the thermal behavior of axial flux synchronous permanent-magnet machines (AFSPMMs) through a 3-D thermal-magnetic finite-element analysis (FEA). This paper offers a systematic approach to magnetothermal FEA. The considered axial flux machine is wound on a soft magnetic compound core. The computation of thermal field is performed via a coupled thermal and fluid-dynamical model based on FEA, where the thermal sources are obtained from a DC current flow model and a magnetostatic model. This paper includes an overview of the finite-element method (FEM) model implementation. Simulation results are presented, and, to validate the model, the simulated surface temperature rise of the motor parts is compared by experimental data.

Electromagnetic and Mechanical design of a Fractional-slot-windings Axial-flux PM synchronous machine with Soft Magnetic Compound Stator

Despite their favorable aspect ratio, axial flux PM synchronous machines can compete with traditional radial flux machines in terms of torque and power density only if the number of pole-pairs is sufficiently high and the ratio axial length/outer diameter is low. Since axial flux PM synchronous machines have an inner stator hole, the number of stator slots is bounded, therefore in order to increase the number of poles per slots fractional slot windings arrangements can be utilized. Frequently, this procedure results into a more compact winding design, resulting in lower copper losses due to shorter end connections. This paper deals with the electromagnetic and mechanical design of a fractional windings axial flux PM synchronous machine with soft magnetic composite featuring low eddy-currents losses at high frequency and self-cooling air channel system. The whole design procedure was done using finite element analysis and multiphysics tools

Design Issues Of A Fractional-Slot Windings Axial Flux PM Machine With Soft Magnetic Compound Stator

The paper addresses some design aspects of a fractional-slot windings axial flux PM synchronous machine whose stator is made with soft magnetic composite. Since Axial Flux PM Synchronous machines have an inner stator hole, the number of stator slots is bounded, therefore in order to increase the number of poles per slots fractional slot windings arrangements can be utilized. Frequently, this procedure results into a more compact winding design, resulting in lower copper losses due to shorter end connections. The soft material used for the stator presents low eddy-currents losses at high frequency, and a self-cooling air channel system is provided. On the other hand, rotor peak temperatures rise more than expected due to rotor eddy currents. In fact, stator MMF subharmonics induce relevant EMFs in the rotor at rated speed. The design procedure is carried out using analytical models.

A tubular generator for marine energy direct drive applications

The paper illustrates the operation of a tubular machine as a linear generator for reciprocating energy sources. Reciprocating energy sources utilization is rapidly increasing nowadays due to the interests in marine energy. Linear generators adopted in marine power plants, offer the advantage of generating without introducing any conversion crank gear or hydraulic system. The use of tubular machine topology allows to improve electromagnetic thrust density. The paper shortly summarizes the principles of the marine wave buoy interaction and reports the design analysis and control of a PM synchronous tubular linear machine based on a scaled prototype

Feasibility of a 10 MW doubly fed induction generator for direct-drive wind turbines

The study considers 10 MW, 600 poles, doubly fed induction generator, allowing direct-drive units with reduced size converter. The work relies on a lumped parameters design and on finite element verifications, and it compares some of its results to the findings of recent literature. The results of the paper evidenced a borderline feasibility of the considered generator.

2-D mechanical and magnetic analysis of a 10 MW doubly fed induction generator for direct-drive wind turbines

Direct-drive wind turbines often require full size converters, especially for latest offshore 10 MW units. This paper contributes to the evaluation of 10 MW, 600 poles, doubly fed induction generators, possibly enabling to reduce the converter size. The work relies on a lumped parameters design procedure and on finite elements mechanical and magnetic verifications, which seem to confirm the technical feasibility of the machine.

Analytical Formulation of Radial Magnetic Forces in PM Linear Tubular Machines with Translator Eccentricity

Due to mechanical couplings, permanent magnet tubular linear machines are subject to eccentricity of the mover and hence to a non uniform circumferential distribution of the no load magnetic field in the air-gap. The intensity of radial forces arising thereof is such that it must be taken into account both for flexion analysis and for choice of bearings. This paper illustrates an analytical formulation of the no load magnetic field distribution in tubular IPM machines with translator eccentricity in order to facilitate the computation of the radial forces. Measurements on two prototypes in a test rig illustrate the validity of the approach.

A Fractional Slot Axial Flux PM Direct Drive

The paper deals with an axial-flux PM synchronous motor (AFPMSM) for a direct wheel drive. Its main feature is the armature winding of the fractional slots type. The choice of a concentrated non-overlapping winding allows a large number of pole pairs to be designed. The paper is aimed at emphasizing the special features of the whole motor drive. Therefore, both machine and control design aspects are targeted. Encoder-less operation of the drive is particularly critical. A vector control scheme is illustrated. A sliding-mode rotor flux estimation scheme is investigated. Its performances are experimentally compared to the encoder operation

Design and implementation of high performance FPGA control for permanent magnet synchronous motor

The paper reports the design of an FPGA implementation of an high performance control for permanent-magnet synchronous motors (PMSM) with sinusoidal flux distribution. The objective of this work is to test a single chip FPGA solution in order to simplify the HW, to allow an easy reconfiguration of the control architecture, and mainly to make a step towards a System on Programmable Chip (SOPC) sensor-less PMSM drive exploiting the high computational throughput of the adopted device. The functional blocks are described in details and simulation results are reported for each of them. Experimental verification has been carried out, with an Altera Stratix II device, with a 5 kW brushless motor. The results show how the proposed platform allows for the sensorless and flux estimation algorithms implementation which will be further developed and tested.

Implementation of an improved direct thrust and flux control for linear induction motors

The paper presents a simple and effective scheme for direct thrust and flux control of a linear induction motor. Space vector modulation allows constant switching frequency operation. The use of a reduced order Luenbergers observer improves controls robustness to parameter uncertainties. The comparison between experimental and simulated data shows benefits and limits of this approach.