200,616 research outputs found
Time-optimal Control Strategies for Electric Race Cars with Different Transmission Technologies
This paper presents models and optimization methods to rapidly compute the
achievable lap time of a race car equipped with a battery electric powertrain.
Specifically, we first derive a quasi-convex model of the electric powertrain,
including the battery, the electric machine, and two transmission technologies:
a single-speed fixed gear and a continuously variable transmission (CVT).
Second, assuming an expert driver, we formulate the time-optimal control
problem for a given driving path and solve it using an iterative convex
optimization algorithm. Finally, we showcase our framework by comparing the
performance achievable with a single-speed transmission and a CVT on the Le
Mans track. Our results show that a CVT can balance its lower efficiency and
higher weight with a higher-efficiency and more aggressive motor operation, and
significantly outperform a fixed single-gear transmission.Comment: 5 pages, 4 figures, submitted to the 2020 IEEE Vehicle Power and
Propulsion Conferenc
Technological Aspects: High Voltage
This paper covers the theory and technological aspects of high-voltage design
for ion sources. Electric field strengths are critical to understanding
high-voltage breakdown. The equations governing electric fields and the
techniques to solve them are discussed. The fundamental physics of high-voltage
breakdown and electrical discharges are outlined. Different types of electrical
discharges are catalogued and their behaviour in environments ranging from air
to vacuum are detailed. The importance of surfaces is discussed. The principles
of designing electrodes and insulators are introduced. The use of high-voltage
platforms and their relation to system design are discussed. The use of
commercially available high-voltage technology such as connectors, feedthroughs
and cables are considered. Different power supply technologies and their
procurement are briefly outlined. High-voltage safety, electric shocks and
system design rules are covered.Comment: 39 pages, contribution to the CAS-CERN Accelerator School: Ion
Sources, Senec, Slovakia, 29 May - 8 June 2012, edited by R. Bailey,
CERN-2013-00
Minimum Race-Time Planning-Strategy for an Autonomous Electric Racecar
Increasing attention to autonomous passenger vehicles has also attracted
interest in an autonomous racing series. Because of this, platforms such as
Roborace and the Indy Autonomous Challenge are currently evolving. Electric
racecars face the challenge of a limited amount of stored energy within their
batteries. Furthermore, the thermodynamical influence of an all-electric
powertrain on the race performance is crucial. Severe damage can occur to the
powertrain components when thermally overstressed. In this work we present a
race-time minimal control strategy deduced from an Optimal Control Problem
(OCP) that is transcribed into a Nonlinear Problem (NLP). Its optimization
variables stem from the driving dynamics as well as from a thermodynamical
description of the electric powertrain. We deduce the necessary first-order
Ordinary Differential Equations (ODE)s and form simplified loss models for the
implementation within the numerical optimization. The significant influence of
the powertrain behavior on the race strategy is shown.Comment: Accepted at The 23rd IEEE International Conference on Intelligent
Transportation Systems, September 20 - 23, 202
A prototype liquid Argon Time Projection Chamber for the study of UV laser multi-photonic ionization
This paper describes the design, realization and operation of a prototype
liquid Argon Time Projection Chamber (LAr TPC) detector dedicated to the
development of a novel online monitoring and calibration system exploiting UV
laser beams. In particular, the system is intended to measure the lifetime of
the primary ionization in LAr, in turn related to the LAr purity level. This
technique could be exploited by present and next generation large mass LAr TPCs
for which monitoring of the performance and calibration plays an important
role. Results from the first measurements are presented together with some
considerations and outlook.Comment: 26 pages, 27 figure
On-a-chip microdischarge thruster arrays inspired by photonic device technology for plasma television
This study shows that the practical scaling of a hollow cathode thruster device to MEMS level should be possible albeit with significant divergence from traditional design. The main divergence is the need to operate at discharge pressures between 1-3bar to maintain emitter diameter pressure products of similar values to conventional hollow cathode devices. Without operating at these pressures emitter cavity dimensions become prohibitively large for maintenance of the hollow cathode effect and without which discharge voltage would be in the hundreds of volts as with conventional microdischarge devices. In addition this requires sufficiently constrictive orifice diameters in the 10”m â 50”m range for single cathodes or <5”m larger arrays. Operation at this pressure results in very small Debye lengths (4 -5.2pm) and leads to large reductions in effective work function (0.3 â 0.43eV) via the Schottky effect. Consequently, simple work function lowering compounds such as lanthanum hexaboride (LaB6) can be used to reduce operating temperature without the significant manufacturing complexity of producing porous impregnated thermionic emitters as with macro scale hollow cathodes, while still operating <1200°C at the emitter surface. The literature shows that LaB6 can be deposited using a variety of standard microfabrication techniques
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