Ricerc@Sapienza

This paper presents a sizing equation system for radial flux (RF) hybrid excitation synchronous machines (HESMs) with coaxial rotors. The system of sizing equations is derived integrating existing literature, mechanical, magnetic, thermal and control strategy considerations and coupled to a computationally-efficient finite element analysis (FEA) to assist the design of wide constant power speed range (CPSR) HESMs.

This paper presents the design and experimental characterization of a radial flux (RF) hybrid excitation synchronous machine (HESM) topologically realized with two coaxial rotor sections, a salient pole wound field (WF) section and an interior permanent magnet section (PM). The machine design choices are analyzed with FEA simulations to predict the behavior at no-load and at nominal load. A no-load 10:1 voltage regulation and CPSR is experimentally characterized along with a partial load dynamometer mapping.

Extended Electro Motive Force observers exhibit good performances at medium and high speeds. However, voltage and current errors, together with parameter uncertainties, lead to inaccurate rotor position estimation. Thus, this paper proposes a novel analytical approach to identify estimated position errors of Extended Electro Motive Force Observers in both the stationary and the estimated synchronous reference frames. A unified analytical framework is presented, that allows to derive a closed-form expression for these errors in both frames.

Extended Electro Motive Force Observers in the estimated synchronous reference frame allow to estimate rotor position at medium and high speeds for Interior Permanent Magnet Synchronous Machines. This paper focuses on the analysis of the dynamic performances of these observers. Use of complex vector modeling allows to demonstrate that these performances are speed dependent. In order to overcome this problem, a Complex Vector Observer is proposed. It is proven that this structure achieves good robustness against load torque and speed variations over different operating conditions.

This paper presents a closed-loop flux-weakening controller for hybrid-excitation synchronous machine drives based on separate regulation of amplitude and phase angle of the armature voltage. Operating point analysis is carried out to investigate the dynamic properties of the drive and to give guidelines in the tuning of the controller. Finally, experimental tests validating the theoretical derivations are performed on a prototype hybrid-excitation drive.