Plug-in hybrid electric vehicle emissions impacts on control strategy and fuel economy

Plug-in hybrid electric vehicle (PHEV) technologies have the potential for considerable petroleum consumption reductions, at the expense of increased tailpipe emissions due to multiple cold start events and improper use of the engine for PHEV specific operation. PHEVs operate predominantly as electric vehicles (EVs) with intermittent assist from the engine during high power demands. As a consequence, the engine can be subjected to multiple cold start events. These cold start events have a significant impact on the tailpipe emissions due to degraded catalyst performance and starting the engine under less than ideal conditions. On current hybrid electric vehicles (HEVs), the first cold start of the engine dictates whether or not the vehicle will pass federal emissions tests. PHEV operation compounds this problem due to infrequent, multiple engine cold starts.The dissertation research focuses on the design of a vehicle supervisory control system for a pre-transmission parallel PHEV powertrain architecture. Energy management strategies are evaluated and implemented in a virtual environment for preliminary assessment of petroleum displacement benefits and rudimentary drivability issues. This baseline vehicle supervisory control strategy, developed as a result of this assessment, is implemented and tested on actual hardware in a controlled laboratory environment over a baseline test cycle. Engine cold start events are aggressively addressed in the development of this control system, which lead to enhanced pre-warming and energy-based engine warming algorithms that provide substantial reductions in tailpipe emissions over the baseline supervisory control strategy.The flexibility of the PHEV powertrain allows for decreased emissions during any engine starting event through powertrain torque shaping algorithms that eliminate high engine torque transients during these periods. The results of the dissertation research show that PHEVs do have the potential for substantial reductions in fuel consumption, while remaining environmentally friendly. Tailpipe emissions from a representative PHEV test platform have been reduced to acceptable levels through the development and refinement of vehicle supervisory control methods only. Impacts on fuel consumption are minimal for the emissions reduction techniques that are implemented, while in some cases, substantial fuel consumption reductions are observed

Experimental implementation of power-split control strategies in a versatile hardware-in-the-loop laboratory test bench for hybrid electric vehicles equipped with electrical variable transmission

The energy management strategy (EMS) or power management strategy (PMS) unit is the core of power sharing control in the hybridization of automotive drivetrains in hybrid electric vehicles (HEVs). Once a new topology and its corresponding EMS are virtually designed, they require undertaking different stages of experimental verifications toward guaranteeing their real-world applicability. The present paper focuses on a new and less-extensively studied topology of such vehicles, HEVs equipped with an electrical variable transmission (EVT) and assessed the controllability validation through hardware-in-the-loop (HiL) implementations versus model-in-the-loop (MiL) simulations. To this end, first, the corresponding modeling of the vehicle components in the presence of optimized control strategies were performed to obtain the MiL simulation results. Subsequently, an innovative versatile HiL test bench including real prototyped components of the topology was introduced and the corresponding experimental implementations were performed. The results obtained from the MiL and HiL examinations were analyzed and statistically compared for a full input driving cycle. The verification results indicate robust and accurate actuation of the components using the applied EMSs under real-time test conditions

Design and Implementation of an Electric Differential for Traction Application

International audienceThe use of an Electric Differential (ED) constitutes a technological advance in vehicle design along with the concept of more electric vehicles. EDs have the advantage of replacing loose and heavy mechanical differentials and transmissions with lighter and smaller electric motors directly coupled to the wheels via a single gear or an in-wheel motor. This paper deals then with an Electric Differential System (EDS) for an Electric Vehicle (EV) directly driven by dual induction motors in the rear wheels. A sensorless control technique is preferred to a position or speed encoder-based control one to reduce the overall cost and to improve the reliability. The EDS main feature is the robustness improvement against system uncertainties and road conditions. The EDS control performances are validated through experiments on a dSPACE-based test bench. The experimental results show that the proposed controller is able to track the speed reference and the curvature angle with good static and dynamic performances

Design and development of a traction motor emulator using a three-phase bidirectional buck-boost AC-DC converter

An industrial drive testing, with a ???real-machine??? can pave way, for some serious issues to test-bench, motor, and the operator. A slight disturbance in control logic amid testing, can damage the physical machine or drive. Such dangerous testing conditions can be avoided by supplanting real motor with a power electronic converter based ???Motor Emulator??? (ME) test-bench system. The conventional ME comprises of two-stage three-phase AC-DC-AC conversion with first-stage AC-DC as emulator and second-stage DC-AC as regenerating unit. This two-stage power conversion, require independent control algorithm, burdening control complexity as well as the number of power electronic switches are quite significant. Therefore, to economize and downsize conventional multistage ME system, this research work experimentally validates a common-DC-bus-configured ME system with only the AC-DC regenerative emulator stage. A bidirectional three-phase AC-DC converter is proposed as the regenerative emulator converter in a common-DC-Bus-configured ME system. The Proposed converter???s operating principle along with mathematical design and control strategy are also presented. To validate the operation of the proposed converter as a common DC-bus-configured emulator, two permanent magnet synchronous motors (PMSM) of 7.5 kW and 2.0 kW are emulated and their simulation and experimental results are presented here. The proposed bi-directional converter inspired from classical buck-boost operation, requires just ten unidirectional IGBT switches preventing any circulating current in the system. The proposed converter also eliminates the regenerative converter stage in classical ME system. Also, the proposed common-DC-bus-configured ME system requires a single stage control unlike independent control in existing ME system. The proposed converter provides four-quadrant operation and emulation of motor under study. The dynamic model of PMSM motor is simulated on the MATLAB simulation platform and the Simulation results are compared with experimental results. From the simulation and experimental results, it is concluded that, with the presented control scheme, the proposed ME converter can be made to draw the same current as a real machine would have drawn, had it been driven by the same DUT. Since, the output current of proposed converter is fed back to DC bus, the input power source requirement is reduced, making the overall ME system more energy efficient

Sähköauton Hardware-In-the-Loop -simulaatio käyttäen Energetic Macroscopic Representation -metodologiaa

Electric vehicles are one of the most promising alternative vehicle propulsion technologies due to their lack of local greenhouse gas emissions and oil dependency. A research project has been put into place to investigate how a commercially existing electric vehicle - the Tazzari Zero - could be modified in order to improve its energetic performance. However, examining different modification possibilities in computer simulation requires a model for the drivetrain of the vehicle. For the goal of describing the energetic performance of the vehicle drivetrain, a static efficiency map model is deemed adequate. An experimental procedure called the on-road efficiency map method has been proposed in order to obtain an efficiency map model for an existing electric vehicle. This is based on instrumenting the vehicle and completing a drive cycle with it. The experimental validation of the on-road efficiency map method is the goal of this Master’s Thesis. The validation of the on-road efficiency map method is performed on a versatile experimental platform that is capable of emulating an electric vehicle following a drive cycle. Hardware-In-the-Loop simulation is used in the implementation of the platform to obtain a good correspondence between the platform and a fully physical electric vehicle. In order to organize the complexity of the platform’s design task and to provide a systematic procedure for control design, Energetic Macroscopic Representation is utilized. The validation results show that there is mostly only a minor error of less than 8% in the efficiency map obtained with the on-road method with respect to the efficiency map obtained by the classic protocol.Sähköautoja pidetään yhtenä lupaavimmista vaihtoehdoista tulevaisuuden autojen voimansiirtojärjestelmiksi, koska nämä eivät tuota paikallisesti kasvihuonekaasupäästöjä eivätkä ole suoraan riippuvaisia fossiilisista polttoaineista. Diplomityöhön liittyvä tutkimusprojekti tutkii miten kaupallisesti saatavilla olevan sähköauton - Tazzari Zeron - energiankulutusta voitaisiin parantaa. Eri kehitysvaihtoehtojen tutkimiseksi tietokonesimulaatioiden avulla tarvitaan kuitenkin malli sähköauton voimansiirtojärjestelmälle. Staattinen tehokkuuskartta tarjoaa riittävän tarkan mallin ajoneuvon energiankulutuksen kannalta. Eräs esitetty kokeellinen menetelmä kykenee tuottamaan tällaisen tehokkuuskartan olemassa olevalle sähköautolle. Menetelmä perustuu mittausantureiden asentamiseen ajoneuvoon ja täten tarvittavan datan keräämiseen testiajosta. Käsillä olevan diplomityön tavoite on tämän menetelmän kokeellinen validointi. Validointi tehdään toteutettavan koejärjestelmän avulla, joka jäljittelee todellisen sähköauton ajonaikaista toimintaa. Jotta tämä koejärjestelmä vastaisi hyvin todellisen sähköauton toimintaa, se toteutetaan Hardware-In-the-Loop -simulaatiota hyväksi käyttäen. Koejärjestelmän laajuudesta ja haastavuudesta johtuen teoreettisena apuvälineenä käytetään Energetic Macroscopic Representation -metodologiaa. Tämä helpottaa järjestelmän matemaattisen mallin jäsentämistä ja tarjoaa systemaattisen proseduurin säätösuunnitteluun. Validointitulokset osoittavat, että validoitavan menetelmän ja vastaavan perinteisen metodin tuottamien tehokkuuskarttojen välinen ero on pieni, enimmäkseen alle 8%