Ottorino Bruno

Innovative Solutions for Overhead Catenary-Pantograph System: Wire Actuated Control and Observed Contact Force

In this paper an innovative active pantograph for high-speed trains is proposed. The results presented are based on extensive simulation tests. The parameters used in the simulation are those of a real pantograph for high-speed trains: the pantograph model is modified by adding a wire actuation, in order to exert a constant contact force between the moving pantograph and the overhead contact wire. A wire-actuated control and contact force observers are proposed as effective solutions in the case of a possible implementation.

Phototube sensor for monitoring the quality of current collection on overhead electrified railways

Abstract A new measurement system able to detect the occurrence of arcing between the pantograph and the overhead contact line was studied and set up. The system uses photomultiplier tubes to measure the duration of the ultraviolet emission due to electric arcing. The major advantages of the system proposed are its non-invasivity with respect to the pantograph equipment, its reliability and its low cost. Correlation with data acquired during high-speed test runs from different sensors (e.g. currents measured in an equipotential wire between the front and the rear pantographs, images acquired from a TV camera), provided the opportunity to perform an efficient calibration and an analysis of selectivity of the phototube sensor. Data from the phototube sensor along with various other information lead to the definition of a reliable index for evaluating the quality of the current collection. The determination of such an index has primary relevance for maintenance activities, for computing the minimal thrusts to be applied to the pantograph at different speeds and for testing new materials for overhead contact wires and collector strips.

Dual-function wheel drives using rotary-linear actuators in electric and hybrid vehicles

Electric and hybrid vehicles represent the future of ground transportation. In such vehicles, electric motor/s provide the propulsion thrust — eventually aiding the engine in case of parallel and mixed powertrains. On the other hand, x-by-wire technologies are spreading, typically using electric drives to also perform actions such as steering, braking, active suspension etc. Any active wheel may then feature up to 4 related degrees of freedom, usually managed by separated drives. This paper proposes to use multi-degree-of-freedom drives, in particular rotary-linear, to integrate more of such basic movements inside a single motor, thus achieving potential benefits on size, weight, cost, complexity etc. Different combinations of functions are examined and the main types of rotary-linear machines found in the literature are briefly recalled and commented, finally focusing on a brushless isotropic rotary-linear machine.

A low-complexity rotary-linear motor useable for actuation of active wheels

The combination of a rotary and linear motion along the same axis is used in several applications, including tooling machines, robotics, automation etc. It may be also used to conveniently manage pairs of basic functions of active wheels in electric and hybrid vehicles. In such cases, rotary-linear machines may represent an interesting alternative to the usual employ of a separated actuator per each basic motion. Anyway, such machines often rely on a structure that is either not suited to be conveniently realized using common materials and manufacturing techniques, or exhibits a complex behavior not permitting an effective decoupled control of force and torque. This paper presents some results concerning the structure, theoretical modeling, FEM analysis, magnetic circuit modeling and drive control for an isotropic brushless machine recently proposed.

A distributed driving and steering system for electric vehicles using rotary-linear motors

The paper presents the activities ongoing in the framework of a two-year Italian National Research Project aimed at developing a distributed Driving and Steering (DaS) system for Electric Vehicles (EVs). The system is built up around an actuation module embedding a rotary-linear motor and including a power converter and a local Electronic Control Unit (ECU) to supply and control the motor. The actuation module is intended to make a wheel active so as to give it propelling and steering capabilities. The DaS system, in turn, includes a central ECU and a fieldbus to govern and network the system, and a power supply stage. The Project under consideration is focused on a DaS system with two active wheels for a light-duty EV.

Harmonics reduction in DSC induction motors with two three phase stator winding sets

A direct self control (DSC) strategy is applied to an induction motor with two three-phase stator winding sets. A remarkable reduction in the electromagnetic torque harmonics, as well as a meaningful minimization of the machine current distortion, are evidenced with respect to a conventional induction motor. In traction applications, electromagnetic torque harmonics induce mechanical stress on the transmission apparatus and cause resonance phenomena. On the other hand, current harmonics interact with signaling transmission, deteriorating their quality. Both drawbacks are greatly reduced in the case of the DSC strategy applied to the proposed unconventional motor. Therefore, the presented results are relevant in electrical traction, showing that the introduction of induction motors with two three-phase stator winding sets offers new interesting solutions.

Active controls and non-invasive monitoring for high speed trains

Abstract International interest is growing for improving performance of the rail transport system. A crucial problem for railway companies is to prevent damages to the overhead line equipment and to pantographs. A brief overview of our research activities is addressed, in the fields of active pantographs and advanced methods for measuring the quality of the current collection for high-speed trains. The pantograph-overhead contact wire interaction is investigated by using a phototube sensor, wavelet transform applied to the line current and infrared camera. The results obtained are relevant for monitoring the quality of the current collection and for a predictive maintenance of the pantograph and of the contact line.

PANDA: A Friendly CAD Tool For PantographDesign And Testing

An interactive, user-friendly and graphically oriented toolbox for pantograph testing and design is presented in this paper. The pantograph structure can be chosen between four different classes: asymmetric, symmetric, scissors-shaped and seesaw-shaped pantograph. The first two classes include traditional as well as active solutions. The toolbox realizes a first software aid for performance evaluation of traditional and/or innovative pantographs.

Effects of saturation on eccentricity force in permanent magnet synchronous machines

Permanent magnets synchronous machines are nowadays widely employed. In case of symmetrical construction, aligned mounting of the rotor and balanced supply, the distributed surface magnetic actions on the rotor feature a null resultant. Anyway, in case of defective assembly or when bearings exhibit a reduced or variable stiffness, the eccentricity of rotor determines a resultant force depending on angular position and currents. This paper investigates such phenomenon for a surface-magnets machine, using FEM analysis to permit keeping into account saturation. Simulation results are reported and commented, highlighting that such force may be affected from stator currents in a counter-intuitive way when magnetic saturation of the core becomes appreciable: in such event, the worst-case scenario required for design purposes must be carefully singled out.

Analysis of a hybrid excitation DC motor

In some niche applications, e.g. emergency pumps operating in case of fire, a high reliability and a constant speed operation capability are basically required. This paper deals with the use of hybrid excitation in DC motors to permit a highly reliable operation under adjustable field supply and unregulated armature supply, e.g. provided by an emergency accumulator. In fact, the field winding permits to retain a possibly adequate speed regulation capability, while the magnets ultimately allow an uncontrolled operation even in case of full failure of the excitation system. The paper presents a preliminary design and its validation and optimization by means of FEM analysis.