G. Rizzoli

Optimized design of a multiphase induction machine for an open rotor aero-engine shaft-line-embedded starter/generator

The aerospace world has found in the progressive electrification of on-board services the way to improve aircraft efficiency, reliability and maintainability. The resulting step change in aircraft electrical loads is impacting on the electrical generation and distribution systems. On the other hand the fuel saving targets is drawing the attention toward new architectures such as counter rotating fans and open rotor jet engines. The integration of the generator on shaft of this kind of engine challenges the electric machine designer in facing, at the same time, the harsh environment and high reliability requirements. The paper presents the design of multi-phase fault tolerant induction machine to be installed on the high pressure shaft of an open rotor jet engine. In particular, the proposed solution is a four-three-phase induction machine.

Multiphase Induction Machine for Aero-Engine Shaft-Line-Embedded Starter/Generator: Scaled Prototypes Testing

The paper presents the experimental testing of two variants of scaled prototype (10 kW) of a four-three-phase fault tolerant induction machine to be installed on the high pressure shaft of an open rotor jet engine. The two machines have the same overall dimensions, but one machine adopts a conventional magnetic core made of thin laminated FeSi alloy while in the other one the rotor is made of FeCo. Starting from the classic experimental tests, the parameters of the prototypes are computed to determine and compare the electromechanical performance of the two solutions.

Control of an open-ended induction machine using a dual inverter system with a floating capacitor bridge

A speed control scheme is proposed for a 3-phase induction motor that uses an open-ended stator winding fed by a dual inverter system with a floating bridge. The floating bridge has a voltage boosting function that extends the constant power high-speed range of the induction machine and operates the main inverter bridge at unity power factor. The proposed control scheme coordinates the two inverters that supply the motor, regulates the dc-link voltage of the floating bridge and boosts the machine terminal voltage at high speed. Simulation results are used to clarify the motor-drive torque capability in the high speed region. Experimental results show that a significant power improvement is achievable in the field weakening region.

Comparison between an AC-DC matrix converter and an interleaved DC-dc converter with power factor corrector for plug-in electric vehicles

Passive three-phase rectifier circuits are very popular for ac-dc power conversion. However, they do not have the capability to reverse the power flow, which is demanded by some recent potential smart-grid applications, such as vehicle-togrid (V2G) power transfer. This paper compares two structures of reversible battery chargers, i.e., an interleaved dc-dc converter fed by a three-phase power factor corrector rectifier and a three-phase ac-dc matrix converter, which may be suitable for plug-in electric vehicles. The comparison aims to estimate the power losses, the power capability and the size of the converters under common requirements.

Use of field harmonics in multiphase induction motor drives for on-line parameter estimation

Multiphase drives are very promising in high power applications, because the total power can be split among several phases. In addition, the higher number of phases allows defining fault tolerant strategies that improve the reliability of the drive. An interesting feature of multiphase machine is the capability of controlling high order space harmonics of the magnetic field, in addition to the fundamental one. In this paper, it is shown how this characteristic can be used to monitor the state of the machine or to estimate the stator parameters that are necessary for field-oriented control.

Design of a two-switch flyback power supply using 1.7 kV SiC devices for ultra-wide input-voltage range applications

This paper presents the design and evaluation of a two-switch flyback power supply with ultra-wide input voltage range (230–1300 V), fed from the floating dc bus of power electronics building blocks (PEBB) in medium voltage (MV) modular multilevel converter (MMC) applications. Rated at 80 W, 48 V output, and operating at 50 kHz, the proposed converter uses 1.7 kV SiC devices and a planar PCB-winding transformer to achieve a low-profile form factor. Further, a pre-charge circuit and start-up sequence are developed as well, enabling the two-switch flyback converter to wake up at 230 V. Experimental results are presented for verification and evaluation purposes.

Modulation strategies for three-phase AC-DC matrix converters: A comparison

The matrix converter rectifier is an AC-to-DC converter that can be considered for emerging applications, related to smart grids and renewable energy production. The most attractive characteristics of this converter are the simultaneous control of the input power factor and the output voltage, and the small volume of the input capacitors. In this paper, after a small review of the modulation techniques, several modulation strategies are experimentally compared in terms of power losses and THD of input and output currents.

Experimental Temperature Modelization for Solar Racing Vehicle

This paper presents an experimental method to model the temperature response of the inverters of the solar car Emilia 3 which is the vehicle build by the Italian Onda Solare team for the World Solar Challenge 2013. Object of this paper is using the experimental data collected to create a thermal model of the inverters to predict dangerous situations and adding it to the energetic model of the overall vehicle powertrain to better simulate racing conditions and help the race strategy planning. The data is elaborated to identify the experimental transfer function between motor current and inverter temperature. The function is validated with the current measurements and its behavior was found to be consistent with the real temperature data.

Injection of third-order spatial field harmonics for sensorless speed estimation in multiphase induction motor drives

It is well-known that in multiphase drives the spatial harmonics of the air-gap magnetic field can be controlled independently of each other. In this paper it is shown how the third-order spatial harmonic of the magnetic field can be used to estimate the rotor speed without the need of a mechanical sensor. Experimental results confirm the feasibility of the developed sensorless speed observer.

Experimental comparison of hard-switching, ZVT and SiC inverters

Various soft switching inverter topologies have been reported in the literature with the aims of reducing the switching losses and dynamic switching stress. However, lower losses are generally regarded as one of the most significant advantages of the emerging silicon carbide semiconductor devices over the conventional silicon devices. Both routes seem viable to improve the converter efficiency. To investigate the optimal solution, this paper experimentally evaluates the efficiency of six prototypes, i.e., three zero-voltage transition inverters differing only in the power switches, and three hard-switching inverters, mounting both silicon and silicon carbide devices. A set of experimental results is included.