Lucio Taponecco

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.

Hybrid-excitation DC machines as highly reliable generators for ram air turbines

Ram air turbines, deployed in the external airflow during flight, are used as emergency power sources to feed the vital apparatuses required for governing aircrafts in case of failure of main supply systems. Such turbines mostly drive electric generators usually connected to a DC bus supported by emergency batteries, which supplies the vital avionic systems. Such generators must then feature high dependability, adequate regulation capability and good overall efficiency. This paper investigates the employ for such purpose of hybrid-excitation DC machines, which may achieve a high reliability thanks to the inherent internal redundancies and to the limited use of electronic components. Referring to a mid-power case-study, a preliminary design and FEM-circuital models purposely developed for validation and design refinement are described, finally reporting and commenting significant simulation results.

SLIDING MODE SPEED CONTROLLER FOR TRAPEZOIDAL BRUSHLESS MOTORS

ABSTRACT This paper describes the application of a variable structure speed controller for a non sinusoidal brushless permanent magnets motor drive. Our trapezoidal brushless motor model changes the working conditions for every phase commutation and moreover it allows to simulate the different structural motor configurations. Controller synthesis is carried out using sliding mode theory with a pole assignment technique. During the sliding motion the state point is forced to reach a prescribed surface due to an active change of the control action. The order of the system is therefore reduced and moreover the dynamic behaviour of the closed-loop system is imposed. Results by digital computer simulation prove parametric variation insensitivity, disturbance rejection, fast transient responses, no overshoot and absence of speed ripples during phase commutations.

Control of an unconventional converter for 3-phase extension of 1-phase mains supply

Due to historical reasons, the most diffused solution for electric energy transmission is via fixed voltage and frequency a.c. grids. A 3-phase symmetric supply results typically preferable; anyway, due to practical reasons 1-phase feeders are mostly used for low-power final distribution up to several kVA. This paper deals with a low-complexity converter that was recently proposed to provide a high power quality reversible interface between 1-phase supply and 3-phase loads. Some improvements in the control system are presented, reporting and commenting simulation results showing better performances under nonlinear, unbalanced and variable loads.

Field oriented adaptive controller using EKF for asynchronous drives

ABSTRACT This paper presents a high dynamic induction motor drive system utilizing a fully digital direct field oriented controller. The drive is characterized by a sliding mode controller and by a stochastic filtering technique, the latter obtained by an extended Kalman filter (EKF), in the feedback loop. The EKF, in addition to supplying a reliable estimation of state variables, is able to identify and to correct in real-time the values of rotor resistance and of rotor constant time, in effect, becoming an adaptive state observer. The system can work both with or without a speed sensor. Some computer simulations are reported.

Analysis and control of a brushless wind generator with maximum power tracking

Wind generators represent a very interesting means for renewable energy harvesting, both grouped in large grid-connected farms and as small units contributing to supply isolated loads such as farms or villages located in remote regions. This paper describes the structure and control of a small-size self-orienting fixed-pitch wind genset using a 3-phase permanent magnets synchronous machine connected to a DC bus via a simplified 2-legs inverter using a split capacitors bank. A maximum power tracking control strategy is investigated allowing compensating for variations of both wind speed and air density. Two simulation models focused on slow and fast phenomena, i.e. max power tracking logic and generator control, are finally described, reporting and commenting some significant results.

An innovative dependable reluctance motor for high-torque low-speed applications

In the framework of a recent Italian National Research Project focused on drive-by-wire systems for industrial vehicles, a high-torque electric actuator was searched complying with stringent requirements in terms of specific performances, cost and dependability. This paper describes the considerations and guidelines that led to the development of an innovative electromagnetic structure for a double-anisotropic reluctance machine, illustrating its features and providing an overview of the theoretical, numerical and experimental results achieved

A switched reluctance machine for high-torque low-speed applications

This paper presents a first overview of an unconventional switched-reluctance rotating machine conceived to provide high specific torque in low-speed applications by leveraging on the magnetic gearing effect while featuring a simple, modular, highly symmetrical structure that should permit to limit manufacturing costs. After recalling the main proposals found in the literature for similar targets, the first application considered for the machine is briefly described. The proposed structure is then introduced and briefly analyzed, highlighting the main features and issues related to manufacturing, performance and control. A few results coming from 3-D FEM analysis of the machine are finally reported and briefly commented

Control of an unconventional rotary-linear brushless machine

Electrical drives employing motors able to directly manage multiple degrees of freedom may result of relevant interest in several application fields, e.g. robotics and tooling machines. This paper recalls first the features of a rotary-linear brushless machine recently introduced, highlighting the ideal possibility to achieve a decoupled force/torque regulation through a suitable supply strategy. A control system for such machine is then presented, using adaptive yet relatively simple regulators. A complete drive structure is finally analysed by simulation using a simplified model suitably developed in Matlab-Simulink/sup /spl reg//.