Mattia Morandin

Traction PMASR Motor Optimization According to a Given Driving Cycle

Electric motors are ideal candidates for traction applications due to their optimal electromechanical characteristic, high efficiency, and manufacturing simplicity. Nowadays, the most attractive solutions are represented by the synchronous machines, due to the great advantages in terms of high performance and mass saving. Motor optimization is often performed in one or few operating points, usually located along the continuous or overload torque profile. On the other hand, the actual motor operation depends on the driving cycle of the vehicle, which might be different than the rated conditions. This paper deals with the design and optimization of a permanent-magnet-assisted synchronous reluctance motor according to two different duty cycles, one for city driving and another for mixed driving operation. A procedure is proposed to evaluate the most effective design areas by means of a series of representative points, which have been considered for the global optimization. The results and the advantages of the adopted methodology against the conventional procedure and optimized solutions are highlighted and discussed.

Outer-rotor ringed-pole SPM starter-alternator suited for sensorless drives

The paper proposes a new outer-rotor configuration for an SPM starter alternator suited to be incorporated in a sensorless drive. To this aim, the rotor has a ringed-pole structure that has been already demonstrated to be adequate for zero and low speed sensorless position detection by a signal injection technique. The paper presents the machine description and modeling, the design of the sensorless drive control, predicted performance by simulations, measures on the motor, and preliminary drive performance test results.

Finite-Element Analysis of Electrical Machines for Sensorless Drives With High-Frequency Signal Injection

A challenge during the design process of an electrical machine is the characterization of the various parameters in a computational time as short as possible. Frequently it is required the computation of the electrical machine parameters that are necessary for the tuning of the drive control algorithm. This paper deals with a strategy to compute the high-frequency signal injection response of a sensorless controlled electrical machine. It allows to determine the self-sensing capability of the machine directly during the design process. Such capability can be defined in any given operating point, for example, along the maximum-torque-per-amps trajectory. Then, also the high-frequency machine parameters can be computed. In addition, the strategy proposed here requires a very short computational time to get such data. After a magnetostatic field analysis, carried out so as to get the torque for a given current, the flux density distribution is stored, and the differential reluctivity tensor is evaluated in each element of the mesh. Then, a time-harmonic analysis is carried out in a linearized structure so as to compute the d - q parameters at the injection frequency. In order to validate the proposed procedure, experimental results on different machine type are included in this paper. This allows to prove the reliability of the procedure as a valued tool for the characterization of the machine.

Analysis and Tests of the Sensorless Rotor Position Detection of Ringed-Pole Permanent-Magnet Motor

To the aim of creating a high-frequency (HF) anisotropy in a surface-mounted PM machine conductive rings are placed around each pole such rings modify the d-axis HF impedance of the machine. A novel strategy is adopted to evaluate the HF signal injection response of such a ringed-pole electrical machine. The self-sensing capability of the machine is evaluated by means of a small-signal model of the machine in the d-q reference frame and finite-element simulations. The impact of the rings on the HF signals achieved in the analysis is validated by the comparison with experimental results.

Design and Analysis of a Novel High-Torque Stator-Segmented SRM

This paper presents a novel switched reluctance motor incorporating a new design methodology. The proposed structure is designed using distinct concepts including design considerations of salient poles and the motor energy conversion capacity. First, multiple techniques to increase the motor torque using these concepts are discussed. Then, the new design is introduced. Based on the concepts of maximum energy conversion and also providing a topology change process, a novel stator-segmented structure is proposed. The three-phase form of the proposed motor has six segments in the stator with four poles and a solid rotor with 22 poles. The novel motors characteristics are initially obtained using finite-element analysis and shown to exhibit higher torque density when compared to the conventional structure. Finally, the performance of the new design and analysis methods described in the paper are verified by experimental results obtained by a built prototype.

A robust integrated starter/alternator drive adopting a synchronous reluctance machine for automotive applications

A synchronous reluctance machine is investigated as a promising solution for integrated starter/alternator applications. For this application the electric machine should exhibit a high torque during the engine start-up and a wide constant-power speed range during electric energy generation. Peculiarities of the synchronous reluctance machine are the possibility of a large torque overload at low speed, its extended flux-weakening capability, and its inherent fault-tolerance. In details, this paper reports the design of the electric machine, the results of finite-element computations, the description of the control system, and the experimental test measurements on the drive prototype.

Finite-element analysis of electrical machines for sensorless drives with signal injection

A challenge during the design process of an electrical machine is the characterization of the various parameters in a computational time as short as possible. To this purpose, the analysis strategies are manifold. In addition, it is more frequent to obtain parameters of the electrical machine that are necessary for the drive control. In this paper, a strategy to compute the high-frequency signal injection response of an electrical machine adopted in a sensorless electric drive is presented. It allows to determine the self-sensing capability of the machine directly during the design process. Such a capability is defined in any given operating points (for instance along the maximum torque per Amps trajectory). In addition, the computational time required to get such data is very short. After a magnetostatic field analysis, carried out so as to get the torque for a given current, the flux density distribution is stored and the differential reluctivity is evaluated in each element of the mesh. Then, a time-harmonic analysis is carried out in a linearized structure so as to compute the d-q parameters at the injection frequency. The proposed procedure is applied to different type of machines and validated by comparison with experimental results.

Integrated Starter–Alternator With Sensorless Ringed-Pole PM Synchronous Motor Drive

The so-called integrated starter-alternator (ISA) is a high-efficiency electrical machine that is connected to an internal combustion engine obtaining mild hybrid electric vehicles. The ISA has a twofold task: starting up the engine and generating electrical energy to be stored into a battery. This paper is focused on the first task. Two different motors are investigated: an external rotor surface permanent magnet (SPM) machine and an interior permanent magnet (IPM) machine. For drive control, both motors require knowledge of their rotor position; then, a sensorless technique based on the high-frequency (HF) voltage injection for rotor position detection has been implemented. In order to create an HF anisotropy in the SPM rotor configuration, a ringed-pole solution has been adopted. Experimental tests have highlighted that the first machine has a clear capability of starting up the engine with good speed and position estimation in spite of the particular nonconstant load torque. As regard the IPM machine, the sensorless engine startup appears not possible because the anisotropy disappears at a high current level due to saturation effects.

On the proprieties of the differential cross-saturation inductance in synchronous machines

The cross-saturation inductance is a mutual inductance due to the saturation of portions of the magnetic circuit of one axis caused by the current of the other axis. In the sensorless drives, the differential cross-saturation inductance causes an error in the estimation of the rotor position when performed by means of the high frequency signal injection methods. The knowledge of the properties of cross-saturation inductance is therefore essential to minimize any distortion effect on the machine control. This paper aims to describe the properties of the cross-saturation inductance for different synchronous machine types, such as reluctance, interior PM and surface PM machine. Information are also given to predict the error in the estimated position for any stator currents useful for implementing an error compensation technique. The analysis is supported by finite element simulations and experimental measurements.

Power-Train Design and Performance of a Hybrid Motorcycle Prototype

This paper deals with the design of the power train for a hybrid electric motorcycle (HEM). The HEM power train is composed of an internal combustion engine coupled to a synchronous electric machine (EM). The EM is fed by a standard three-phase inverter connected to a high-voltage battery pack. Low weight and volume are the main requirements for HEMs, and the energy storage system (ESS) is the most critical part. Different kinds of ESSs are compared to choose the best solution balancing cost, volume, and weight. A methodology of investigation is proposed in order to recognize all the data necessary to find out the ESS. Moreover, the design choices adopted for the electric drive are reported. In order to predict EM, power converter, and battery pack performances, efficiency maps have been computed. The whole power train has been prototyped. Experimental tests of the HEM prototype on test bench and on a real racetrack are presented. All the experimental measurements highlight a significant performance enhancement of the new HEM with respect to the original one. The HEM acceleration time and top velocity have been improved without affecting too much the original motorcycle weight.