1,721,041 research outputs found
Motor Overvoltage and Power Losses Analysis in Industrial AC Drives Based on Si and SiC Devices
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Inverter Side RL Filter Precise Design for Motor Overvoltage Mitigation in SiC Based Drives
No full textThis study investigates the use of resistor-inductor (RL) filters for motor overvoltage issues caused by cables connecting inverters to electric machines. Using existing filter design formulae and fixing the desired peak motor voltage, an RL filter was designed for a 15 kW industrial drive. This filter was used with a Si IGBT inverter and a matching between the design targets and the experimental results was found. Using the same filter with an SiC MOSFET inverter, a detrimental effect in overvoltage mitigation task was found. From simulations, it was noticed that combination of filter resistor parasitic inductance and high dv/dt causes unpredicted additional high-frequency motor overvoltages. These phenomena require higher filter inductance values with respect to the standard one, thus previous filter design formulae cannot be used. New design formulae, valid when inverters with high dv/dt are used, are proposed and experimentally validated. Interestingly, using the proposed formulae, it was discovered that the best filter resistance is not equal to the characteristic impedance of the cable. A design guideline that permits to optimally design the RL filter without simulation tool, considering the resistor parasitic inductance and the inverter dv/dt is finally proposed
Low torque ripple tooth coil windings multi-3-phase machines: design considerations and validation
No full textIn multi-n-phase machines, the n-phases are grouped in separated stars. A particular subcategory of multi-n-phase machines is the multi-3-phase machines. This study presents the design considerations and their validation for tooth coil wound multi-3-phase machines. A generic algorithm to design multi-3-phase machines is proposed. Although this study mainly focuses on multi-3-phase machines the approach is generalised and is applicable to any multi-n-phase machine. The resulting machines exhibit a low torque ripple value, and a mathematical formulation is proposed in order to justify this behaviour. All the multi-3-phase machines designed according to the proposed algorithm can be studied, and directly compared, thanks to the generalised harmonic formulation of the stator MMF and the torque performances here proposed. This study is enriched with some design hints useful to realise a machine with low mutual coupling between phases, and some considerations that can help the machine designer in the choice of the number of poles. The design algorithm is applied for the design of a triple-3-phase PM-inset machine solution, with nine slots ten poles. The performances, evaluated by finite element analysis and experimental analysis, demonstrate the effectiveness of the design algorithm proposed in a very simple structure machine
Simple parameters estimation and precise over-voltage simulation in long cable connected drives
No full textOver-voltage at the motor side when supplied by Voltage Source Inverter (VSI) using long cables could cause winding failure and it is known to be source of electromagnetic disturbances, both radiated and conducted. In this paper, the over-voltage prediction for such drives in industrial environment has been investigated. Minor run time execution and precise simulations are the main paper targets. A novel cable model has been considered for motor over-voltage and converter overcurrent estimation. Two different measurement methodologies for the model parameters have been introduced too. The first methodology is accurate and could measure both the proposed parameters needed by the application and the filter parameters needed to mitigate these problems. The second is simpler and could only estimate the filters parameters. Comparison between experimental and simulation results are presented in the paper to confirm the proposed method
PWM Carrier Displacement in Multi-N-Phase Drives: An Additional Degree of Freedom to Reduce the DC-Link Stress
Full text linkThe paper presents a particular Pulse Width Modulation (PWM) strategy to reduce the (Direct Current) DC-link capacitor stress for multi-n-phase drives. A multi-n-phase drive is composed of multiple independent systems of n inverter supplying a multi-n-phase electric machine. The paper focused on the investigation of the best phase shifting between carriers for a triple-3-phase drive compared to the 3-phase counterpart in order to reduce the capacitor bench design point. Simulation and experimental results show as the control technique proposed is able to reduce the value of the DC-link capacitor current in any operating condition including fault case. In this sense, the PWM carrier displacement appears like an additional degree of freedom that can be exploited in multi-n-phase drives but also in multi-motor application
Circular Economy and the Fate of Lithium Batteries: Second Life and Recycling
No full textThere is a growing demand of electrochemical energy storage, driven by automotive and stationary requirements. Lithium‐ion batteries (LIBs) are expected to dominate the market from the current 0.5 TWh to about 2.5 TWh in 2030. This will lead to great difficulties in the procurement of critical raw materials and in the management of end‐of‐life systems. From a circular economy perspective, it is necessary to identify reuse and recycling strategies that can make the demand fully sustainable. However, second life and recycling are not mutually excluding, while the final fate of the battery, or at least of its noblest components, should be recycling instead of disposal. In this context, to allow new strategies such as direct recycling of cathode powders, an accurate redesign of the battery system, from the single cell to the modules, which allows ease of separation of the compartments, should be considered. The correct evaluation of the best strategies cannot be separated from an accurate and transparent life cycle assessment (LCA), which would take into account both economic and environmental aspects. Herein, the most advanced recycling methods are analyzed and the issues underlying the efficient reuse and recycling of battery packs from electric vehicles are critically discussed
A study on cobalt substitution in sodium manganese mixed-anion phosphates as positive electrode materials for Na-ion batteries
No full textSodium polyanionic materials provide various structural frameworks compared to their lithium counterparts, leading to diverse studies on novel polyanion-based electrode materials for sodium ion batteries. Na4M3(PO4)2P2O7 (M = Mn, Fe, Co, Ni, and Mg) is a new class of mixed-anion phosphates combined with two polyanion groups, (PO4)3− and (P2O7)4−. It is an attractive electrode candidate because of its stable cyclability and low volume changes upon cycling. Although Mn-based mixed-anion phosphate materials have shown a high redox potential of 3.8 V vs. Na+/Na, they have suffered from low electrical conductivity and structural distortion upon oxidation. Partial substitution of Mn by other divalent cations is an efficient strategy to suppress lattice distortion and to affect the phase transition process during electrochemical cycling. Here we study the cation substitution effect of the Mn-based mixed-anion phosphates on the phase stability and the kinetics of the electrochemical reaction. The electrochemical reversibility was found to be improved by certain cation substitution. In particular, Co substitution not only increased the operating voltage but also enhanced both cyclability and rate capability. Furthermore, we investigate the phase changes upon cycling using in situ synchrotron X-ray diffraction, supporting the positive effect of the mixed-anion phosphate structure through cation substitution. © 2019 Elsevier B.V.
A coupled mechanical-electrical simulator for the operational requirements estimation in a dynamic IPT system for electric vehicles
Full text linkThe paper presents a simulation tool for the study of a dynamic IPT system. This simulator is able to provide information about the electrical components in function of the dynamic behaviour of the vehicles during the charge operations. The results are used to investigate different possibilities for the improvement of the interfacing between the IPT system and the electrical grid to which it is connecte
Theoretical and experimental comparison of two interoperable dynamic wireless power transfer systems for electric vehicles
Full text linkThe paper discusses two wireless power transfer systems for the charge of electric vehicles during the motion. The systems are conceived to be interoperable with the same receiver structure. Both systems are supplied by means of the same power electronics architecture and are based on the series-series compensation of the coils. In one of the presented systems a high-frequency transformer is used at the transmitter side. The two solutions are analyzed and compared pointing out their advantages and drawbacks. Results of experimental tests are presented to demonstrate the operations of both systems
Fast hardware protection for a series-series compensated inductive power transfer system for electric vehicles
Full text linkThe paper proposes a simple solution to a safety problem encountered during the development of a series-series compensated IPT system for electric vehicles. This problem is related to the equivalent current source behavior of the receiver side in presence of an unpredicted load disconnection. A pure analog hardware system able to manage this fault protecting the filtering elements of the system is proposed. The system is investigated by means of a circuit simulation then its physical implementation is presented. The effectiveness of the proposed solution is experimentally proven
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