Vincenzo Delli Colli

A Tubular-Generator Drive For Wave Energy Conversion

This paper illustrates the operation of a tubular-machine drive as a linear generator for a heave-buoy wave energy conversion. Linear generators, which are adopted in marine power plants, offer the advantage of generating without introducing any conversion crank gear or hydraulic system. The use of a tubular-machine topology allows the electromagnetic thrust density to be improved. This paper briefly summarizes the principles of marine wave buoy interaction and reports the design analysis and control of a permanent-magnet (PM) synchronous tubular linear machine based on a scaled generator prototype and on a rotating simulation test bench

Single Wheel longitudinal traction control for electric vehicles

The traction control is a tool to increase stability and safety and it has a greater performance potential in electrical vehicles (EVs) than in internal combustions vehicles. Moreover, the traction control allows the EV to operate more efficiently preventing slippage in acceleration and permitting the use of use high-efficiency low-drag tires. The presented approach can compete with the well-recognized techniques, but it offers a lighter tuning procedure. This paper presents an approach to the longitudinal control of a single wheel adopting a configuration based on an adherence estimator and a controller of the adherence gradient. Two adherence gradient controllers are examined in the paper: a fuzzy controller and a sliding mode controller. In both cases, the presented approach allows for tracking a value of the adherence derivative in a wide operating range without any knowledge of the road conditions. The work is based on numerical simulations as well as experimental tests. The test bench computes in real-time the vehicle dynamic and loads accordingly, the drive under test. Both controllers were experimentally verified showing good behavior and good response to a sudden change in the road characteristics, whereas the best overall performance was recorded with the sliding mode control

Analytical and Multiphysics Approach to the Optimal Design of a 10-MW DFIG for Direct-Drive Wind Turbines

This work deals with a 10-MW doubly fed induction generator (DFIG) for direct-drive operation of wind turbines with a reduced-size converter. The work includes a lumped parameter design, an optimization procedure, a finite-element analysis (FEA), and an electrical performance assessment. A monetary cost was assumed as a cost function, and an approximation of the construction cost as a function of the axial length was obtained. The found solutions were checked by FEA in order to assure the mechanical feasibility. Further verifications were developed to allow a conclusive performance evaluation. The optimization improved the cost of the proposed DFIG, including materials, losses, and converter, making it slightly cheaper than an available permanent-magnet synchronous generator.

Thermal Analysis of an Axial Flux Permanent-Magnet Synchronous Machine

The paper presents a thermal analysis of an axial flux synchronous permanent-magnet machine (AFSPM) with a core of soft magnetic composite (SMC) material. We obtained the temperature distribution by using a coupled thermal and fluid dynamic finite-element model. The study considers two 2-D approaches and compares their results to experimental tests.

A System-on-Chip Sensorless Control for a Permanent-Magnet Synchronous Motor

This paper investigates a system-on-programmable-chip permanent-magnet synchronous-motor drive speed and position sensorless control. The proposed approach exploits two field-programmable gate-array capabilities, namely, the fast computation and the hosting of long finite-impulse response filters. Such filters allow an accurate reconstruction of the position signal by means of phase compensation and lead to an improved speed estimation based on the zero-crossing detection of the commutation signals. This paper presents the design flow and confirms the feasibility of the approach by means of hardware-in-the-loop simulations and experimental tests.

Modeling and Control of a Zero-Current-Switching DC/AC Current-Source Inverter

Choosing a dc/ac converter is mainly a compromise among three major issues, namely: 1) efficiency; 2) waveform quality; and 3) cost. This paper considers a zero-current-switching (ZCS) current-source inverter (CSI) as a viable choice for many applications. It features low conduction and switching losses, inherent output filtering, capability of withstanding short circuits, and the opportunity to use thyristors. Despite these promising characteristics, this inverter exhibits a nonlinear relationship between the modulation index and the output current. Moreover, the resonant modes that are generated by the load-filter interaction must be damped. Since the previous aspects require a proper control law, a model of the system is very useful for defining and tuning a control structure. Thus, after providing a functional overview of the ZCS dc/ac CSI, this paper formulates a large-signal model and then derives and simplifies the averaged one. Numerical data are used to validate the models that are obtained. An active damping control for a motor drive is defined and tuned by means of the simplified averaged model, and its effectiveness is numerically validated. Experimental results conclude this paper.

Voltage control of current source inverters

The current source inverters may become direct competitors of the voltage source inverters thanks to the voltage control techniques. The paper proposes an improved voltage control technique for current source inverters, that chooses the current vectors relying on bang-bang controllers. This technique is compared to a well-established one using current space vector modulation and synchronous-frame proportional and integral controllers. The presented controller is explained and validated by means of off-line as well as real time simulations and experimental tests. The numerical results prove that the proposed control technique produces less distorted voltage waveforms in terms of total harmonic distortion and spectrum. According to the real-time simulations performed the proposed control technique is computationally less expensive than the benchmark. Finally, the experimental results obtained confirm the feasibility of the proposal.

Comparison of Axial Flux PM Synchronous Machines With Different Rotor Back Cores

Rotor losses of axial flux permanent magnet (PM) synchronous machines with fractional windings depend on stator magneto-motive force (MMF) harmonics. To reduce rotor losses, a soft magnetic composite rotor can be used. This paper focuses on the comparison between two machines with the same soft magnetic composite stator and different rotor cores: one of solid steel and another of soft magnetic composite. The study evidenced the composite rotor improved the power density and the efficiency. Moreover, it highlighted a nonlinear salient-pole operation of the composite rotor machine, mainly connected to spatial harmonics.

Design of a System-on-Chip PMSM Drive Sensorless Control

The Sliding-Mode Position and Speed Observer is a simple and well-known mechanical sensor-less solution for Permanent Magnet Synchronous Motors (PMSMs) that is inherently robust in the medium-high speed range. The paper proposes a Field Programmable Gate Array (FPGA) implementation of a simple observer exploiting the high computational power of the device aiming to improve the speed estimation behavior and to make a step towards a System on Programmable Chip (SOPC) sensor-less PMSM drive.

Cryogenic Characterization of Copper-Wound Linear Tubular Actuators

Electrical machine power density can be increased by liquid nitrogen (LN) cooling, since these machines operate at low resistivity and have a high heat transfer coefficient. This paper describes the experiments carried out on a short stroke tubular linear permanent magnet machine with copper windings and LN cooling. A cryogenic test rig for linear actuators was designed and built, and tests were carried out aimed at highlighting inherent current limiting capability, electric parameter variation in the fall from room to cryogenic temperatures, and actuator high thrust density. Shear stress reaches 17.8 kN/m2, and thrust-to-copper-loss ratio is 4 N W-1/2, which are significantly better compared to conventional actuators.