O. Honorati

Performance of a 10 kW power electronic interface for combined wind/PV isolated generating systems

The hoped exploitation of pollution-free, low cost, renewable energy resources has always stirred up interest and inventiveness. The double-input single-output DC/DC power converter discussed in this paper, developed for combined wind-photovoltaic generating systems, aims to mitigate the output power fluctuations due to the intermittent nature of both solar and wind energy. Digital control of the whole apparatus also contributes to optimise the converter modes of operation, running both the energy input circuits at their maximum power level. The paper reports an overall description of the power interface characteristics and experimental results recorded in extensive laboratory tests of a 10 kW rated prototype.

Modular, axial-flux, permanent-magnet motor for ship propulsion drives

Original features such as compactness and lightness make slotless axial-flux permanent-magnet machines (AFPMs) eligible for application in large power motor drives devoted to the direct drive of ship propellers. This paper discusses characteristics of AFPMs designed for application in marine propulsion, and machine performances such as efficiency, weight and torque density are evaluated for a comparison with those of conventional synchronous machines. A newly-conceived modular arrangement of the machine stator winding is proposed and experimental results taken from a small-size machine prototype are finally shown.

Performance of coreless-winding axial-flux permanent-magnet generator with power output at 400 Hz-3000 rev/min

An axial-flux permanent magnet machine (AFPM) topology with a coreless winding is proposed for generator units required aboard ships, aircraft or hybrid-electric vehicles. In the proposed AFPM configuration, the winding consists of rhomboidal shaped coils encapsulated in fibre-reinforced epoxy resin. The coils have a double-layer arrangement to leave space for a cooling water duct being used to remove heat directly from the interior surface of the winding. The overall machine structure has high compactness and lightness, and because of the lack of the iron core generator operation with power output at 400 Hz can be accomplished with high efficiency and acceptable voltage regulation. The paper discusses the basic design and construction of AFPM generators with coreless winding and experimental results taken from a 16 poles machine prototype rated 70 kW, 3000 rev/min are finally reported.

AC brushless drive with low-resolution Hall-effect sensors for surface-mounted PM Machines

An ac brushless drive in which Hall-effect sensors are used as rotor position sensors is presented in this paper. Three different methods to obtain a high-resolution position estimation from the low-resolution sensors are described and compared through simulation and experimental testing. The proposed control algorithms most innovative feature is its adaptability to the entire speed range, including startup, when using any of the three estimation algorithms. The control algorithm has been implemented and tested in order to drive a slotless axial-flux permanent-magnet (PM) machine for domestic appliance applications.

Compact wheel direct drive for EVs

Concerning the application of slotless axial-flux PM motor (AFPMs) in electric vehicle drives, this article deals with the development of a 16-pole AFPM prototype which is used in the propulsion system of an electrical scooter. The proposed AFPM prototype has 45 Nm peak torque and 6.8 kg mass of active materials, and it is coupled directly to the scooters rear wheel. In the following, the authors discuss the design and construction of the motor prototype and report experimental results taken from machine laboratory tests. Finally, they give details concerning the motor drive arrangement used in an electrical scooter prototype.

Low-cost compact permanent magnet machine for adjustable-speed pump application

The variable-speed driven pump can result in significant energy conservation where reduced flow rates are required for long periods of time. In regard to adjustable-speed pump drives, one major contribution of this paper is the demonstration that a permanent magnet (PM) motor based on the slotless axial-flux permanent magnet machine (AFPM) topology can be a suitable candidate to advantageously compete with the induction motor for such a low-cost drive application. For the purpose of a cost comparison, the paper discusses design and construction of a prototype machine which has been conceived to replace a 1.2 HP induction motor being used in a standard adjustable-speed pump drive. Results taken from laboratory tests of the prototype machine are reported, together with an assessment of the machine manufacturing cost.

Axial-flux permanent magnet motor for direct-drive elevator systems without machine room

This paper deals with design and construction of two twin prototypes of slotless axial-flux permanent-magnet motor drive jointly developed by SIMINOR Ascenseurs and the University of Rome for application in direct-drive elevator systems without machine room. Each prototype of a pulley-direct drive motor is rated 5 kW, 95 rev/min, and has shaft height of 380 mm and overall axial thickness of about 80 mm. Machine design based on unusual specification and original manufacturing solutions adopted for the proposed direct-drive elevator arrangement are discussed throughout the paper, including the leading dimensions and characteristics of the prototype motors. Finally, experimental results taken from the machine prototypes are reported.

Ironless Axial Flux PM Machine With Active Mechanical Flux Weakening For Automotive Applications

Because of their high compactness and lightness, together with high efficiency, axial-flux PM (AFPM) machines are among the most suitable candidates for several automotive applications. As a drawback, they are limited in speed range because voltage rises linearly with speed. For this reason, they are generally considered not well-suited for applications such as starter/alternators. As a solution, in this paper an AFPM ironless machine prototype with extended flux weakening capabilities is proposed. Flux weakening, and therefore output voltage regulation, is achieved mechanically through a small-sized actuator that displaces each other the two adjacent windings that compose the stator

Compact Permanent-Magnet Machines

ABSTRACT The availability of new high-field permanent-magnet materials has created opportunities for novel topologies of electrical machines with advantageous characteristics such as high efficiency and good power/weight ratio. A disc-type arrangement, with slotless winding and axially-directed flux in the air gap, has particularly short axial length and is well suited for system integration as either generator or motor. Applications include auxiliary power units, electric vehicle drives and wind power generation.

Rotor bars breakage in railway traction squirrel cage induction motors and diagnosis by MCSA technique Part II : Theoretical arrangements for fault-related current sidebands

In a companion paper (Part I) the bar breakages for a 1.13 MW induction motor used in high speed railway traction drives were studied, by simulating the whole system (converter + motor) and by analyzing frequencies and amplitudes of current sidebands, for various loads (both active and inertial) and with increasing fault severity. It was recognized that faults can be characterized by (1-2s)f sideband, but results vary with load torque and drive inertia. Other sidebands appear less dependent from these disturbs, like (5+2s)f. Unfortunately, no works presented simple and general formulas about sidebands. In this paper, theoretical formulations for computation and prediction of rotor fault-related sideband frequencies and amplitudes are given, aiming to obtain relations useful for diagnostic purposes (fault severity assessment by MCSA), and by using Part I as a case-study. A decomposition by multiphase symmetrical components is performed, taking in account space harmonics. Formulas for (1-2s)f sideband amplitude are carried out, extendable to many other sidebands.