Magnet shape optimization of surface-mounted permanent magnet synchronous machine through FEA method

This work analyzes the effects of permanent magnet shape on the performance of surface - mounted permanent magnet (SPM) machine, including average torque, c ogging torque, magnet volume and de - magnetization limit. Analytical expressions are introduced to obtain the relationship between magnet shape and torque behavior s . Secondly, a multi - objective Differential Evolution (MODE) algorithm is used to get the best tradeoff model between torque performances. An automatic design process via MODE for SPM motor with magnet shaping is introduced. All the models are validated by Finite Element Analysis (FEA)

Automatic Tuning for Sensorless Commissioning of Synchronous Reluctance Machines Augmented with High Frequency Voltage Injection

Sensorless control of synchronous reluctance motors relies on the knowledge of the machine current-to-flux maps. Previous work demonstrated the feasibility of sensorless identification of the flux maps, performed by exciting the machine with square-wave voltage pulses at standstill, and without the need of rotor locking. The rotor position was initially estimated and then used throughout the identification, in open-loop fashion. In some cases, rotor oscillation and eventually position drift led to stop the identification before the programmed dq current domain was covered entirely. In this paper, the rotor position is closed-loop tracked during the motor commissioning to counteract the occurrence of rotor movement. The hysteresis-controlled excitation voltage is augmented with a high-frequency square-wave voltage component, and the position is tracked through demodulation of the current response to such high-frequency component. The proposed approach is experimentally verified on a 2.2 kW synchronous reluctance motor prototype. The results show that the id, iq commissioning domain is substantially extended, resulting in more accurate flux maps. Moreover, self-tuning of the method is addressed and possible causes of error are analyzed and commented

Integrated Isolated OBC for EVs with 6-phase Traction Motor Drives

This work deals with a new topology of on-board integrated battery charger intended for road electric vehicles equipped with a 6-phase traction motor drive. The proposed OBC topology deeply integrates the battery charger within the e-drive powertrain, thus reducing cost and volume of the charger respect to non-integrated solutions. Moreover, galvanic insulation is provided, differently from all fully integrated charger in the literature. Finally, the charger has embedded PFC capability, so the AC grid current is absorbed at unitary power factor and low THD. Extensive simulation results show the feasibility of the proposed solution

FEA-Augmented Design Equations for Synchronous Reluctance Machines

The synchronous reluctance machine is an attractive substitute of induction motors and synchronous PM motors thanks to its higher efficiency and lower cost of materials, respectively. One of the main challenges relenting the adoption of these machines is the lack of a widely recognized procedure for their design. In the past, design equations were proposed for SyR machines by different authors. Those models represent a good starting point and a useful guideline for the designer, but they are far from being accurate enough in many aspects. To increase precision, different procedures based on finite element analysis were proposed over the years, but those methods have the dual downside of losing the physical insight on the effect of the various design parameters. In this work, a comprehensive design procedure based on design equations is reviewed and improved using few static FEA simulations to fix the errors of the analytical model, in order to increase the precision without reducing the generality of the model

Sensorless Synchronous Reluctance Motor Drives: A Projection Vector Approach for Stator Resistance Immunity and Parameter Adaptation

The paper presents a general projection vector framework for the analysis of flux and position observers applied to sensorless control of synchronous reluctance machines, with emphasis to parametric errors sensitivity. The stator resistance immunity property of Adaptive Projection vector for Position error estimation (APP) technique is demonstrated, in maximum torque per ampere (MTPA) conditions. Out of MTPA, additional resistance adaption is devised for accurate estimation of stator flux and torque. Alternatively, inductance adaptation might be preferred to resistance's, when dealing with inaccurate motor flux-maps. Inductance adaptation is shown to decrease the steady-state position error. All proposed APP observers with adaptation techniques are subjected to stability analysis. The merit and the feasibility of the proposed scheme is experimentally demonstrated on a 1.1 kW synchronous reluctance (SyR) machine test-bench

Standstill Determination of PM Flux Linkage Based on Minimum Saliency Tracking for PM-SyR Machines

Permanent Magnet assisted Synchronous Reluctance (PM-SyR) motors often present relevant magnetic saturation, especially if overload capabilities want to be exploited. The knowledge of current-to-flux relationship is mandatory for proper motor control, and it becomes even more critical in case of sensorless applications. Reliable self-commissioning tests have been recently developed for Synchronous Reluctance (SyR) motors without producing any rotor movements. This procedure can be extended to PM-SyR motors, but, being at standstill, it does not retrieve the flux contribution related to the PMs. This paper integrates the identification of the flux characteristic including a novel test for estimating the PM flux, obtaining the complete magnetic characteristic of PM-SyR motors. The global identification session is performed at standstill and without a position transducer, while the load can either be connected or not. These conditions are considered the most demanding for selfcommissioning tests. The machine is first excited with a proper sequence of bipolar high voltage pulses to determine its current dependent flux component. Then, the PM flux linkage is retrieved at standstill by evaluating the local saliency along the negative q axis. The proposed method was experimentally verified on a 10 kW PM-SyR motor prototype, with an estimation error of 0.42%

Sensorless Synchronous Reluctance Motor Drives: A Sensitivity Analysis Framework and Design to Achieve Stator Resistance Immunity

The paper presents a generic framework for analysis of stator resistance variation in the stability of position observers. The adverse impact of the resistance error on the active flux based sensorless control is studied. A new technique, Adaptive Projection vector for Position error estimation (APP), is proposed to have inherent immunity to resistance errors; in addition, a resistance adaption is devised for accurate estimation of stator flux and torque. The observers are subjected to stability analysis. The instability of active flux control and the merits of the proposed technique are experimentally demonstrated on a 1 kW synchronous reluctance machine test bench

Sensorless Control of Synchronous Reluctance Motor Drives: Improved Modeling and Analysis Beyond Active Flux

The paper presents a framework for the design and analysis of position observers for sensorless control of synchronous reluctance machines. An improved inductance model is developed to account for the position error induced inductance variations. The instability regions of active flux based position observer are analytically identified and validated. A novel technique, Adaptive Projection vector for Position error estimation (APP), that alleviates the stability problems is introduced. Furthermore, the proposed technique can be augmented with a second projection vector to estimate speed error independently of the position error, referred to as Adaptive Projection vector matrix for Position and Speed error estimation (APPS). Stability and performance of proposed technique is validated on a 1 kW synchronous reluctance motor test bench

FEAfix: FEA Refinement of Design Equations for Synchronous Reluctance Machines

The Synchronous Reluctance (SyR) machine is an attractive substitute of induction motors and synchronous PM motors thanks to its high efficiency and low cost of manufacturing. Yet, its design cannot be considered a mature topic, especially for what concerns the rotor geometry. Design equations were proposed for SyR machines by different authors, representing a good starting point and a useful guideline for designers, but they are far from giving accurate results. Conversely, the design procedures based on finite element analysis tend to rely on the brute force of optimization algorithms rather than on the designer’s insight. In this work, a comprehensive design procedure is proposed, where design equations are complemented by the use of the iron saturation curve and the new fast FEA approach named FEAfix. This corrects the equations results via few static FEA simulations per design plane, i.e. per family of machines, rather then by FEA simulating the single machine under design. The general conclusion is drawn that the considered analytical model alone tend to overestimate torque by as much as 40% (average on the design plane). Upon augmenting equations with the saturation curve, the average overestimate drops in the vicinity of 10% error. Finally, the proposed FEAfix refinement guarantees 2% to 1% torque evaluation error, depending on the admitted computational time. High precision is therefore obtained while retaining the generality of the analytical approach