Search Results

The trend towards battery voltage vacuum fluorescent displays continues the technological advances in design and construction of VFD's, as they are applied to the automobile environment. With the ever increasing use of electronic displays for electronically tuned radios (ETR's), compact disc (CD) players, and other entertainment systems, advances in battery voltage displays and their associated drive circuitry have become a necessity. With the inherent advantages of low voltage operation and high information density, VFD's will continue to dominate the automobile audio markets. This paper will discuss battery voltage displays, the basic circuitry necessary to operate a vacuum fluorescent display, and comment on the “off the shelf” controller and driver circuitry available.

This paper shows some aspects of the automotive voltage energy system level shift from 14 to 42 Volts. New features and prospective emissions/fuel economy requirements are creating electrical power needs in future automobiles, which today's conventional system cannot adequately supply at 14 Vdc (nominal, with a 12 Volt battery). It will be necessary to provide electric motors, DC/DC converters, inverters, battery management, and other electronic controls to meet higher voltage requirements. Suppliers must now include 42 Volt components and systems within their product range and make these new components as light, small, and cost efficient as possible. This paper is a compilation of several published works aiming to offer a synthesis to introduce this subject to the Brazilian Automotive Market.

This paper provides an overview about the consequences of a 14/42 V - Electrical Power Supply System for the Electrical Interconnection and Switching Technology. It presents design guidelines and solutions for connector systems including advanced applications like fuse and relay boxes and gives an overview of those existing connectors already suited for 42 V and even higher voltages. The problem of arcing due to the increased voltage is discussed for the case that mating and unmating under load has to be taken into consideration. Arcing also has a tremendous impact on the design of 42 V proof relays. Therefore, some basic results be presented along with proposals how these problems can be overcome by appropriate designs. Another part of the paper looks at the electrical power supply system itself. Here interconnection techniques for new battery systems are discussed. Finally, the chances for new technologies are highlighted.

The High Voltage Power Distribution Unit (PDU) is constructed of magnesium in support of Fuel Cell Electric Vehicle (FCEV) weight reduction efforts. The PDU distributes and controls a nominal 75 kilowatts of power generated by the Fuel Cell, the primary source of High Voltage power, to all the vehicle loads and accessories. The constraints imposed on the design of the PDU resulted in a component highly susceptible to general and galvanic corrosion. Corrosion abatement was the focus of the PDU redesign. This paper describes the redesign efforts undertaken by Ford personnel to improve the part robustness and corrosion resistance.

THE BATTERY is the primary component limiting electric vehicle performance that equals today's standard of expectations as defined by the I. C. engine powered vehicles. Efforts to optimize the electric vehicle performance is leading many people to select and assemble the highest efficiency components available. High voltage electric vehicle power system can provide performance advantages over lower voltage systems, but only if this voltage is in balance with the total system. Mixing high efficiency components does not Insure total system efficiency optimization. The ability of a battery to release its stored energy is a function of its demand. Higher current demands will reduce the efficiency of a battery. This paper reveals how such a mismatch occurred and its reflection on what appeared to be a battery problem.

The 42-Volt electrical system is being introduced in automobiles to provide the extra power needed for various electromagnetic devices. These paper discuses the opportunity offered by the 42Volt for powder metal parts and the challenges. Major opportunities are in motors. A brief discussion of motors and the performance requirements for the magnetic core material used is included. Brushless motor design can benefit the most from insulated iron powder compacts because of the design simplicity of powder metal parts and three dimensional flux capability which is most beneficial in rotating devices.(P/M stands for powder metallurgy and not permanent magnets)

The growing electrical power demands on bus electrical systems, such as the electric door operator, power steering, braking, air conditioning, windshield wipers, seat heating, and the need to improve emissions and fuel economy, are making current 12/24-volt electrical systems inadequate. For buses to continue to meet growing customer needs, electrical power must be increased. The industry is currently pursuing a 42-volt system as standard. In the U.S., that number (42 volts) was selected by an industry-wide research consortium led by the Massachusetts Institute of Technology. The switch to a 42-volt system would revolutionize the automotive industry. This would enable more electronic components and new technologies to be added to the vehicle. At the present time, the discussion and implementation of the 42-volt system is largely on luxury vehicles. The potential benefit of the system on heavy duty vehicles has not been fully explored.

A few years ago, the automobile industry agreed to adopt standards for a new voltage for the production and use of electrical power. The perception was near universal that 14 Volts was at the limits of its capability, and that 42 Volts would be adopted in a rush. The universal perception was wrong. Since then, much of the auto industry has encountered hard financial times. In a totally separate development, parts suppliers introduced innovations at 14 Volts, some of which a few years ago were thought to require 42 Volts. Today, there are 42-Volt cars and trucks for sale, but only at numbers far lower than necessary to begin to achieve economies of scale. But the factor which caused the industry to develop the 42 Volt standard, the growth of electricity use on motor vehicles, continues with no sign of letup. Further, the true technical obstacles to adoption of 42 Volts have been discovered and at least provisionally solved.

The electrification of accessories using a fuel cell as an auxiliary power unit reduces the load on the engine and provides opportunities to increase propulsion performance or reduce engine displacement. The SunLine™ Class 8 tractor electric accessory integration project is a United States Army National Automotive Center (NAC™) initiative in partnership with Cummins Inc., Dynetek™ Industries Ltd., General Dynamics C4 Systems, Acumentrics™ Corporation, Michelin North America, Engineered Machine Products (EMP™), Peterbilt™ Motors Company, Modine™ Manufacturing and Masterflux™. Southwest Research Institute is the technical integration contractor to SunLine™ Services Group. In this paper the SunLine™ tractor electric Air Conditioning (AC) system is described and the installation of components on the tractor is illustrated. The AC system has been designed to retrofit into an existing automotive system and every effort was made to maintain OEM components whenever modifications were made.

With the increase of hotel and ancillary loads and replacement of engine driven mechanical and hydraulic loads with electrical loads, automotive systems are becoming more electric. This is the concept of More Electric Cars (MEC) that necessitates a higher system voltage, such as the proposed 42V, for conventional cars. In this paper, the development of the 42V electric power system for vehicle applications is reviewed. The system architecture and motor drive problems associated with the 42V electric power system are analyzed. Solutions to these problems are also discussed.

The growth in electrical power demand in future vehicles is expected to significantly exceed the four to five percent annual increases experienced over the last two decades. Continued electrification of traditionally mechanical loads, such as power assist steering, as well as the introduction of new loads, such as AC power points, will overburden the conventional 14V power generation and distribution system. The cost of the electronics to control these new high power systems will add to the challenges associated with the transition. A higher electrical system voltage will be required to meet these ever increasing loads and will help to reduce the control electronics costs. This paper will provide projections of potential future electrical system loads and compare some approaches that could be employed to provide the electrical power to meet the needs.

Fuel economy and emission reduction assume significant importance for automotive research activities and conversion of many mechanical / hydraulic loads to electrical loads helps in realizing this objective. As a result, many electrical power hungry loads are anticipated to be introduced soon in global market with average power requirement exceeding the practical limit of the present automotive electrical system implying the necessity of a suitable higher voltage system. Many OE and component manufacturers have come to a consensus to choose 42V as the system voltage for future passenger cars considering various aspects. This paper highlights the advantages of the high voltage system together with some of the issues associated with the new system.

As the vehicle electrical system migrates to the recommended 42-volt system in the future, 42V incandescent lamps will not be practical due to their short filament life. Alternatives to incandescent lamps are discussed. However, due to the inherent simplicity and cost advantage over alternatives, incandescent lamps remain the light source of choice for the auto manufacturer. A scheme to power the current 12V incandescent lamp directly from the 42V line will be presented as a viable low cost solution for the 42V system. This scheme utilized pulse width modulation (PWM) which eliminates the use of expensive DC to DC converters. Implementation schemes, preliminary results, advantages and issues are presented.

Mild hybridisation, using a 48 V system architecture, offers fuel consumption benefits approaching those achieved using high-voltage systems at a much lower cost. To maximise the benefits from a 48 V mild-hybrid system, it is desirable to recuperate during deceleration events at as high a power level as possible, whilst at the same time having a relatively compact and low cost system. This paper examines the particular requirements of the battery pack for such a mild-hybrid application and discusses the trade-offs between battery power capabilities and possible fuel consumption benefits. The technical challenges and solutions to design a 48 V mild-hybrid battery pack are presented with special attention to cell selection and the thermal management of the whole pack. The resulting battery has been designed to achieve a continuous-power capability of more than 10 kW and a peak-power rating of up to 20 kW.

The tighter exhaust emissions standards introduced by governments for light duty vehicles are challenging car manufactures to meet at the same time legal emission limits and fuel efficiency improvements, still providing excellent fun to drive characteristics. The Hybrid and Diesel propulsion systems are two important players on that competition. In this scenario, the 48 V hybridization has the potential to become a cost-effective solution compared to High Voltage systems, outlining a new way to approach the well-known trade-off between CO2 and NOx in Diesels. Aim of this study has been to investigate the benefits offered by a P0 48 V Hybrid system when coupled with a 1.6 L Diesel engine in a 7-seat multi-purpose vehicle.

Vertical-Junction-Field-Effect-Transistors (VJFETs) are currently the most mature SiC devices for high power/temperature switching. High-voltage VJFETs are typically designed normally-on to ensure voltage control operation at high current-gain. However, to exploit the high voltage/temperature capabilities of VJFETs in a normally-off high-current voltage-controlled switch, high-voltage normally-on and low-voltage normally-off VJFETs were connected in the cascode configuration. In this paper, we review the high temperature DC characteristics of VJFETs and 1200 V normally-off cascode switches. The measured parameter shifts in the 25°C to 300°C temperature range are in excellent agreement with theory, confirming fabrication of robust SiC VJFETs and cascode switches.

In this study, the effect of corona discharge on the combustion phenomenon has been made clear. A homogeneous propane-air mixture was used and six equivalence ratios were tested. For generating the positive and negative corona discharge, a non-uniform electric field was applied to the combustion chamber by the needle to plane gap. One or five needle-shaped electrodes were used to change the corona discharge state. When the positive corona discharge was applied, the luminescence from corona with five electrodes was weak as compared with that of one needle-shaped electrode. When the negative corona discharge was applied, the luminescence from corona and combustion were not affected by the number of electrode. When the positive corona discharge was applied by low voltage, the combustion was improved in the case of one needle-shaped electrode, but the index of combustion with one needle-shaped electrode was almost equal to that of five electrodes when the high voltage was applied.

A 1200-V, 600-A silicon carbide (SiC) JFET half-bridge module has been developed for drop-in replacement of a 600-V, 600-A IGBT intelligent power module (IPM). Advances in the development of SiC field effect transistors have resulted in reliable high yield devices that can be paralleled and packaged to produce high-voltage and high-current power modules not only competitive with existing IGBT technology but the modules have expanded capabilities. A SiC vertical junction field effect transistor VJFET has been produced with the properties of lower conduction loss, zero tail current, higher thermal conductivity, and higher power density when compared to a similarly rated silicon IGBT or any practical SiC MOSFETs previously reported. Three prototype SiC JFET half-bridge modules with gate drivers have been successfully integrated into a three-phase 30-kW (continuous), 100-kW (intermittent) AC synchronous motor drive designed to control a traction motor in an electric vehicle.

We describe the details of a particular compact and robust Corona Discharge Device (CDD™) that generates non-thermal plasma in the harsh environment of a stoichiometric exhaust. This particular CDD™ can generate plasma power of up to 15W at exhaust gas temperatures to 850C. Optimizations of geometry, material selection, and thermal design were performed by a combination of simulation and experiment. This particular design considered tradeoffs of several factors, including plasma power, EMI shielding, thermal durability, high voltage interconnection, packaging size, and exhaust emissions reduction. This particular CDD™ was designed to meet most of the same durability and survivability specifications as an O2 sensor, since both are exposed to similar exhaust environments.

Advanced combustion engines dominate all automotive applications. Future high efficiency clean combustion engines can contribute significantly to sustainable transportation. Effective ignition strategies are studied to enable lean and diluted combustion under considerably high-density mixture and strong turbulences, for improving the efficiency and emissions of future combustion engines. Continuous discharge and multi-site ignition strategies have been proved to be effective to stabilize the combustion process under lean and EGR diluted conditions. Continuous discharge strategy uses a traditional sparkplug with a single spark gap and multiple ignition coil packs. The ignition coil packs operate under a specific time offset to realize a continuous discharge process with a prolonged discharge duration. Multi-site ignition strategy also uses multiple ignition coil packs.