01 Preface

This book differs from other automotive engineering texts in that it covers a technology that is still very much in the emerging stages, and will be particularly valuable for design courses, and projects, within engineering degree studies. Whereas other works cover established automotive disciplines, this book focuses on the design stages, still in process for electric vehicles, and thus draws on a somewhat tentative source of references rather than a list of the known major works in the...

04 Electricdrive fundamentals

While battery-electric vehicles were almost as common as IC-engined ones, at the beginnings of the commercialization of the powered road vehicle, it was not until the interwar years that serious studies were taken into operating efficiency of such systems, as a precursor to their introduction in industrial trucks and special purpose vehicles such as milk floats. Figure 0.4 illustrates some of the fundamental EV traction considerations as the technology developed. For the Mercedes Electromobile...

12 Case for electric vehicles

The current world population of motor vehicles stands at 700 million, of which over 600 million are owned in G7 economies1. This number is set to increase to around 1000 million in the next ten years. The bulk of this growth is expected to occur in Second World countries where per capita income is reaching levels where car ownership is known to commence. This has two serious implications (Fig. 1.1) a large increase in the usage of hydrocarbon fuels and an increase in Fig. 1.1 Life expectancy...

1212 Controller For A 45 kW Ac Motor Brushless Dc Or Induction

The drive consists of a 3 phase PWM Drive which feeds the 3 phase motor. The beauty of this arrangement is that the motor can be disconnected and the mains fed to the inverter arms to give a high power battery charger, by phase locking the PWM to the mains. An alternative to this arrangement is for the inverter to put power back into the mains. In case of fault, three alternistors provide current limit protection. In the brushless DC case, the motor permanent...

129 Electrical System Design Challenge

What are the design problems for the electrical system The first one is cost. Unless the final product is attractive to the consumer, we do not have a market. Where are we now For 1000 off systems at 45 kW, a brushless DC motor would cost 1000, a controller 2000, and a battery 2000 (lead-acid). These 1992 prices will reduce with mass production. The second design challenge is one of methodology. Electric vehicles have been traditionally built by placing motor and batteries then spreading the...

22Battery performance existing systems

All battery technologies can offer some solution to the peak power problem but there is only one parameter which ultimately matters, and this is the internal resistance of the cell. This is much more related to cell geometry than cell chemistry, as we shall discover. When AA, C, D and F cells were originally designed, nobody was thinking of discharging them at hundreds of amps, so it is hardly surprising that they are not ideal for the purpose. This problem will become even more extreme as...

23 Status of the aluminium battery

In 1997, patents were filed in Finland for a new aluminium secondary battery. The inventor was Rainer Partanen of Europositron Corporation who claims major improvements in power density and energy density for the new cell based on a 1.5 V EMF2. The author is interested in this problem because it represents one of the last major barriers to be overcome before the widespread introduction of electric and hybrid vehicles. In recent years, significant effort has been directed at improving secondary...

234patent Protection

The technical background to the invention is the result of a remarkable discovery in the field of complex electrochemistry and is based on the composition of the solution for electrical analysis and catalysis, releasing the energy potential of aluminium. Patent protection is being applied in three areas (1) The first is a solution which, under discharge, generates a reaction on the cathode side causing the energy potential of the aluminium to be released, and by ionization changes the molecular...

24 Advanced fuelcell control systems

This section considers the development of a fuel-cell controller and power converter for a vehicle weighing 2 tons, for operation in an urban environment10. The techniques employed can be used with either PEM membrane fuel cells or alkaline units. The main challenge is to re-engineer a high cost system into a volume-manufactured product but this is unlikely to be achieved'overnight'. What is required is a new generation of components which are plastic as opposed to metal based. The power...

242 Cost Reduction Stra Tegies For Fuelcell Controls

The cost of the fuel-cell controller (Fig. 2.15) is split up, at present, as follows 20 each on pumps and compressors valves and actuators programmable logic controller DC DC converters sensors and transducers. The challenge is to achieve a 5 1 cost reduction for mass-market viability. Fig. 2.16 Hydrogen air blowers shown to left of drive electronics. Fig. 2.16 Hydrogen air blowers shown to left of drive electronics. The hydrogen pump (shown left in Fig. 2.16) is a side channel blower and has...

243 Fuelcell Control Valves And Actuation

Selecting suitable valves with such a diverse array of media and operating conditions has not been easy, Fig. 2.17. In fact the valves themselves are neither expensive nor heavy. The problem area is the actuators and it is intended to redesign these for the next version. Currently there is no safety legislation in place for hydrogen powered vehicles. The onus is on the supplier to demonstrate fitness for purpose and that all reasonable precautions have been taken. It is felt this will change...

245 Sensors And Transducers

This is perhaps the hardest area in which to reduce the cost. The devices operate under hostile conditions and are currently made to order. One success has been to reduce the cost of the 2 kW preheater from 1000 to 200 by a complete redesign. In other areas there has been success in combining functions such as the flow meter and the temperature controller in the KOH loop. A complete new family of low cost sensors is needed before production cost targets can be met. Fig. 2.18 Mitsubishi 80 I O...

246 Fuelcell Future Prospects

It is early days for vehicle fuel cells and the main challenge is better, lighter, cheaper, more convenient to use parts - preferably plastics. Insulated packaging of semiconductors is the main issue in the DC DC converters at low voltage and heavy current. This in time will lead to control systems with lower parts count and greater reliability. As we get down the learning curve, and volumes increase, costs will fall. Major improvements in fuel storage, oxygen enrichment and stack materials...

25 Waste heat recovery key element in supercar efficiency

In the longer term vehicles will be electrically propelled using flywheel storage, hydrogen fuel cells or both. These systems potentially offer high cycle efficiencies, and low emissions vital to improving air quality in our big cities11. Bill Clinton's initiative for US family cars to achieve 100 miles per gallon by 2003 is a serious challenge to the engineering industry see Chapter 4. Current solutions include lightweight structures, reduced running losses and small engines. However, the...

252 The Turbine Recovery Scheme

In this scheme the concept is to use a small turbine system in association with an electric generator. Figure 2.21 illustrates the conceptual realization of the idea. Some modelling of the turbine shows that, for reasonable efficiency, speeds of150 000 rpm are necessary. If such speeds can be achieved the sizes of the components will be tiny. For example, for 10 kW, the rotor of the generator will be 25 mm diameter by 15 mm long. The generator needs to be kept separate from the turbine stages...

253 Thermoelectric Genera

The turbine recuperator technique involves some very high technology mechanics to make the system work. It prompts the questions Is there any other way of achieving the same objective Is a solid state solution possible Thermoelectrical devices were invented in 1821 and are perhaps best known today for the small fridges we have on our cars and boats to cool food and drinks. An array of bismuth telluride chips 40 mm square can produce 60 watts of cooling with a temperature differential of 20 C....

32Electric truck motor considerations

EV motor makers Nelco say the requirements for traction motors can be summarized as light weight, wide speed range, high efficiency, maximum torque and long life. The company recently developed their diagonal frame Nexus II motor, for general electric truck operation. In this motor, Fig. 3.1, active iron and copper represent 50 and 30 respectively of the motor weight. Holes in the armature lamination, (a), have resulted in some weight reduction and the use of a faceplate commutator, (b), has...

33 Brushless DC motor design for a small car

In this case study of the design of a 45 kW motor1 commissioned for a small family hatchback -the Rover Metro Hermes - the unit was to give rated power from 3600-12 000 rpm at a terminal voltage of 150 V AC. The unit has been tested on a dynamometer over the full envelope of performance and methods for improving the accuracy of measurement are discussed below. The results presented show a machine with high load efficiency up to expectations and the factors considered are important in minimizing...

331 Brushless Motor Fundamentals

A key aspect of motor design for improved performance is vector control, which is the resolution of the stator current of the machine into two components of current at right angles. Id is the reactive component which controls the field and Iq is the real component which controls the power. Id and Iq are normally alternating currents. In this example, Fig. 3.3, the machines being considered are of the rare-earth surface-mounted magnet type with a conventional 3 phase stator and a rotor...

332 Motor Design Method Of Measurement

In the following account details are given of the motor design, Fig. 3.4, and of the predicted and measured efficiency maps. The measured efficiency maps were carried out using a variable DC link voltage source inverter. Polaron conducted the trials with two waveforms a square wave with conduction angle 180 and a square wave with harmonic reduction, conduction angle 150 , the purpose being to assess the effects of the harmonics on motor performance, (a). Overall length Pole number Peak torque...

334motor Control

Battery operated drives must make optimum use of the energy stored in the battery. To do this, the efficiency of both motor and driveline are critically important. This is especially true in vehicle cruise mode typically two-thirds speed one-third maximum torque, therefore Polaron proposed to build a drive with two control systems (i) current source control in constant torque region and (ii) voltage source operation in constant power region. At 45 kW 6000 rpm we would expect IL 175 A, VAC 150 V...

34 Brushless motor design for a medium car

Here the task is to optimize the 45 70 kW driveline for the family car of the future2. This involves improvements in fundamental principles but much more in materials and manufacturing technology. The introduction of hybrid vehicles places ever greater demands on motor performance. It is the long-term aim of the US PNGV programme to reduce the cost of 'core' electric motor and drive elements to 4 dollars per kW from around 10 dollars charged in 1996 for introductory products supplied in volume....

35 Brushless PM motor design and FE analysis of a 150 kW machine

High speed permanent magnet (PM) machines with rotor speed in the range from 5000 to 80 000 rpm have been developed3, applications of which include a gas turbine generator with possible application in hybrid electric vehicles. The motor considered below runs at infinitely variable speeds up to 2 kHz at full power and has been designed for different requirements at an output power of150 kW. Machine parameters have been calculated from software package 141 developed at Nelco Systems Ltd. The...

352rotor And Stator Configuration

Main constraints were found to be weight and inductance in the high speed application it is important to keep the weight to a minimum, therefore a ring design is the most suitable which means a sufficient number of poles is required on the rotor, 8 poles in this case. The main advantage with this configuration is that the return path for the magnetic circuit in the core and yoke is much smaller in cross-section area (the thickness of the ring has been considered within the customer's shaft...

353magnetic Material Selection

High energy-density rare earth magnets, of samarium cobalt, have been chosen in this design because of the material's higher resistance to corrosion, and stability over a wide temperature range. Also it has a high resistance to demagnetization, allowing the magnetic length of the block to be relatively small. This shape of block lends itself to being fixed onto the outside diameter of the rotor hub, to produce the field in the d-axis, which gives advantages of a greater utilization of the...

355brushless Machine Drive

The machine drive consists of a polyphase, rotating field stator, a permanent magnet rotor, a rotor position sensor, and the electronic drive. During operation the electronic drive, according to the signals received from the rotor position sensor, routes the current in the stator windings to keep the stator field perpendicular to the rotor permanent field, and consequently generates a steady torque. Conceptually, the drive operates as the commutator of a DC machine where the brushes are...

356 Motor Design Finiteelement Modelling

3D finite-element modelling (FEM) was not required, as the topology of the machine in x-y plane is the same along the axial length, except at each end where the end turns winding exists. However, a 2D finite-element model has been employed for the machine to calculate and analyse the flux distribution in it, Fig. 3.10. This is done to facilitate the rotor movement relative to the stator, so that the characteristics of interest such as the flux modulation due to slot ripple effect on the magnet...

36 High frequency motor characteristics

In the 1970s motor designers were introduced to Bipolar Darlington transistors which permitted switching up to 2 kHz at mains voltage. In the 1980s insulated packaging was mastered and motor costs have been reduced. In the 1990s we have the IBGT which permits operation to 16 kHz for the first time at high power. This gives the designer a new freedom4. Hitherto the market sector has been dominated by 50 Hz machine designs. Now we can choose our operating point so the question must be asked what...

361 Hf Machine Properties

Motors designed for high frequency operation are of many types however, they all share common design attributes. The 50 Hz motor designer will be used to the idea that at the full-load operating point copper loss iron loss. This is not true for HF machines - iron loss dominates, accounting for up to 80 of the losses. Another factor is the power density which is in general 5-20 times greater. The use of HF windings means that the number of turns on a winding is reduced. So a high frequency motor...

363open Loops Or Closed Loops For Induction Motors

In the early days of inverter drives, open loop operation of induction motors was the main objective. Generally this is satisfactory over a 10 1 speed range but is problematical at slow speed due to harmonic torques stability problems - especially with low load inertias and lack of rotor cooling. Vector control may be used to improve stability and can be applied on an open loop basis. To do this, estimates are used for the load inertia rotor current and lead to errors where fast dynamics are...

365surface Mounted Magnet Synchronous Machines

This design is first choice for high power drives. The rotor consists of a steel sleeve to which the magnets are glued and a containment band fitted on the outside. This fits inside a standard stator with water jacket. This design is practical up to 0.5 megawatts at up to 100 000 rpm and is used for traction drives. Another benefit is that the output frequency is no longer related to shaft rpm and multipole designs speeds over 3000 rpm may be considered. Using vector control, voltage and...

366ironless Pm Synchronous Motor

This machine has been developed by UNIQ (USA) for hub mounted motors for use in electric vehicles. It consists of a machine with both an internal and external rotor which are mechanically linked and a thin stator winding which is usually fabricated using printed circuit techniques. The result is a lightweight machine with a very high power density and low winding inductance since there is no stator iron. Performance is largely determined by the quality of permanent magnet used. The d-axis...

367wound Rotor Synchronous Machine Withbrushless Excitation

This machine is sometimes used for inverter drives in addition to the well-known use as an electricity generator. The presence of the exciter rectifier means that this solution is applied at higher powers. The rotor can be salient pole or of surface slot construction at high speed. Whichever solution is chosen, the full field thermal loss in the motor is significant and a particular problem if the machine is to be run slowly at high load torques. This type of machine is used in traction drives...

371 Motor Drives Why Change The System

Because the system is already subject to change brought about by new requirements and developments. First, we have the introduction of sealed battery systems. These will permit much higher peak powers than hitherto possible and consequently will run at high voltages. 216 V DC is a common standard working with 600 V power semiconductors. Second, we have the introduction of hybrid vehicles. This will result in the need for drives and motors to operate for long sustained periods - previously...

372vehicle Dynamics And Motor Design

A vehicle represents a large inertia load with certain elements of resistance some of which increase with speed see Chapter 8. For a small family car, mass 1250 kg at 60 mph (26.8 m sec) typical cruising speed. Windage accounts for 6 kW, rolling resistance 2 kW and brake drag 2 kW, a total of 10 kW in steady state conditions. Windage varies as the 3rd power of vehicle relative velocity with respect to the wind. Kinetic Energy 1 2 MV2, where M mass 1250 kg and V velocity in metres sec. So we...

376device Protection In A Motor Controller

Switches Sj-S4 form a bridge converter and the devices require protection against overvoltage spikes from circuit inductances. The main factors are (1) minimize circuit inductances by careful layout. The key element is the position of D9 and associated decoupling capacitor relative to Dj-D4 (2) fit 1 mF of ceramic capacitors across the DC bridge S1 S4 plus varistor overvoltage protection. DrD4 can be normal rectification grade components but D9 must be a fast diode with soft recovery. D5-D8 are...

378power Diagram For Motoring And Charging

Figure 3.18 presents the combined circuit diagram for motoring and battery charging. Reservoir capacitors and mode contactors have been added. The capacitors function as snubbers when running in motoring mode. As drawn, to adapt to battery charging, the battery plug is moved to outlet D and the mains inserted into plug B, alternatively contactors could be used to do the job. Battery safety precautions comprise (1) the battery is connected via a circuit breaker capable of interrupting the full...

38 Lightweight Electric Hybrid Vehicle Design 233 Newconcept Aluminium Ba Ttery

The cell invented by Rainer Partanen, Fig. 2.8, is an attempt to defeat the disadvantages of the aluminium-air cell. It is a secondary battery which uses coated aluminium for the anode and pure aluminium for the cathode. The electrolyte is a mixture of two elements (a) an anion cation solution currently consisting in proportion of 68 g of 25 ammonia water mixed with 208 g of aluminium hydroxide, and made up with water to give 1 litre of solution (b) a semi-organic additive consisting of metal...

411what Is A Fuel Cell

The easiest way to describe a fuel cell is that it is the opposite of electrolysis. In its simplest form it is the electrochemical conversion of hydrogen and oxygen to water, as shown in Fig. 4.1. Hydrogen dissociates at the anode to form hydrogen ions and electrons. The electrons flow through the external circuit to the cathode and the hydrogen ions pass through the electrolyte to the cathode and react with the oxygen and electrons to form water. The theoretical electromotive force or...

412types Of Fuel Cell

Fuel cells are described by their electrolyte Alkaline - AFC Phosphoric acid - PAFC Solid Polymer - SPFC (also referred to as proton exchange membrane - PEMFC) Molten carbonate - MCFC Solid oxide - SOFC. Fig. 4.1 Basic chemical reactions in a fuel cell. The reaction shown in Fig. 4.1, with hydrogen ion transfer through the electrolyte, is only applicable to fuel cells with acid electrolytes and solid polymer fuel cells. The reactions in each of the fuel cell types currently under development1...

42 Reforming and other hydrogen feedstocks

The prime source of hydrogen for fuel cells is by reforming a hydrocarbon, particularly natural gas. The hydrogen production can be carried out either at a central large-scale facility, or immediately upstream of the fuel cell, including on board for transport applications. Steam methane reforming is the main commercially applied process for hydrogen production, with an annual global production capacity in excess of 40 million t a and single units with capacities greater than 400 t d. Overall...

43 Characteristics advantages and status of fuel cells

The main characteristics of fuel cells, arranged in ascending order of operating temperature, are given in the following table The quoted status and efficiencies are typical of systems in 1999 and are based on electricity as a percentage of the lower heating value of hydrogen consumed. Efficiency is discussed in more detail in the next section. The alkaline fuel cell has the advantages of using cheap materials quick to start and high power density. The main disadvantages are the corrosive...

45 Process engineering of fuel cells

The discussion in the last section refers to the system efficiency h and an indication of the engineering role in the development of a practical fuel cell system can be seen in Fig. 4.4, which . s support material . s support material shows how a single SPFC cell is designed to ensure even distribution of the reactants over the electrodes and the importance of catalyst distribution. The figure also shows a group of cells built into a small stack, but before addition of the manifolding for the...

463 Fuelcell Vehicle Prospects

The real future is with fuel-cell cars because the Precept version so fitted will have a fuel-cell stack volume ofjust 1.3 ft3 and produce 70 kW continuously, 95 V at 750 A, Fig. 4.7. Plate current density is 2 A cm2 the cell is currently world leader in PEM-stack design and if used intelligently has higher power density than a thermal engine. This is, then, the turning point, and it is underlined by Mercedes whose work on the Necar IV is showing that 38 efficiency is obtained from hydrogen in...

464 Ba Ttery Electricshybrids In The Interim

EV technology will be needed for the future fuel-cell car but currently it cannot be proven with current traction batteries which are too heavy, too expensive and made from materials that are not in plentiful enough supply. Most good quality batteries are based on nickel technology and the reason for being in this difficulty is not because the battery research Fig. 4.7 GM's PEM fuel-cell stack capable of powering a 1500 kg vehicle. programme was a failure, but rather the reverse. The outcome is...

471 Motor Constraints

There is now general acceptance that the brushless DC motor will be the one used now and in the future. At a conference in Toronto in June 2000, GM gave details of its latest version, with inverter, in the Precept car. Compared with their earlier induction motor drives, they have halved the size by going to the permanent-magnet motor as well as reducing current consumption, for equivalent performance, by a factor of 1.8. They thus also have an inverter of half the size of that required for an...

472wheel Motors And Package Design

While wheel motors are ideal for low speed vehicles the problem of high suspended mass rules them out for cars. Road damage can be caused at wheel hop frequencies and the perceived threat of losing traction on one wheel, by a single motor failure, would prevent any safety authority from issuing a certificate of roadworthiness. Use of such devices as active suspension makes them possible on medium speed urban buses where road wheel tyres can be as much as one metre in diameter and large brake...

473alternative Auxiliary Power

Consideration of photovoltaic power is often a pastime of EV promoters but 10-15 light to electricity conversion efficiency has precluded serious traction usage so far, though use as an auxiliary power source is important. Even at high noon in the tropics solar radiation can only generate 1 kW m2 which means that the solar cell will produce only 150 W for each square metre. In the Honda Solar Challenger, 8 m2 of solar cells generates 1-1.5 kW, which would be nowhere near enough to provide...

491 Parallel European Union And Japanese Initiatives Cited Bythe Us Government

According to TASC, the European Union (EU) has formed the European Council for Automotive Research and Development (EUCAR) in response to both the US PNGV programme and accelerated vehicle development in Japan. EUCAR's objectives are technology leadership, increased competitiveness of the European automotive industry and environmental improvements. With a leader appointed from industry, EUCAR has requested a budget of over 2.3 billion from the EU over 5 years, representing a 50 EU government...

524 Sodium Chloridenickel

Sodium chloride (common salt) and nickel in combination with a ceramic electrolyte are used in the ZEBRA battery, Fig. 5.4, under development by Beta Research (AEG and AAC) and Siemens. During charging the salt is decomposed to sodium and nickel chloride while during discharge salt is reformed. Its energy density of 90 Wh kg exceeded the target set by the USA Advanced Battery Consortium (80 Wh kg energy density, to achieve 100 miles range under any conditions and 150 W kg peak power density to...

562ford Ext11

An early key US initiative in AC drives was the Ford EV project EXT11, Fig. 5.19, which has been exploring the use of an alternating current drive motor in the Aerostar Minivan, seen at (a). A sodium-sulphur battery was employed and a single-shaft propulsion system. A battery with the following specification was involved nominal voltage 200 V minimum voltage at 60 kW, 135 V 50 kW capacity on FUDS cycling 60 kW maximum power (20 seconds) and 35 kW continuous Fig. 5.18 Citroen Berlingo Dynavolt...

571 General Motors Zafira Projects

GM and its Opel subsidiary are aiming at a compact fuel-cell driven vehicle by 2004, Fig. 5.23. By 2010, up to 10 of total sales are expected to be taken by this category. The efficiency of cells tested by the company is over 60 and CO2 emissions, produced during the reformation of methanol to obtain hydrogen, are about half that of an equivalent powered IC engine. Fuel cells have already been successfully exploited in power generation, at Westervoort in the Netherlands, and experimental...

572ford P2000

Mounting most of the fuel-cell installation beneath the vehicle floor has been achieved on Ford's FC5, seen as a static display in 1999, with the result of space for five passengers in a medium-sized package. Their aim is to achieve an efficiency twice that of an IC engine. The company point out that very little alteration is required to a petrol-distributing infrastructure to distribute methanol which can also be obtained from a variety of biomass sources. Oxygen is supplied in the form of...

573liquid Hydrogen Or Fuel Reformation Fig 525

Renault and five European partners have produced a Laguna conversion with a 250 mile range using fuel-cell propulsion. The 135 cell stack produces 30 kW at a voltage of 90 V, which is transformed up to 250 V for powering the synchronous electric motor, at a 92 transformer efficiency and 90-92 motor efficiency. Nickel-metal hydride batteries are used to start up the fuel cell auxiliary systems and for braking energy regeneration. Some 8 kg of liquid hydrogen is stored in an on-board cryogenic...

574 Prototype Fuelcell

Daimler-Chrysler's Necar IV, Fig. 5.26, is based on the Mercedes-Benz A-class car and exploits that vehicle's duplex floor construction to mount key propulsion systems. The fuel cell is a Ballard proton exchange membrane type, 400 in the stack, developing 55 kW at the wheels to give a top speed of 145 km h and a range of 450 km. Fuel consumption is equivalent to 88 mpg and torque response to throttle movement is virtually instantaneous. While the first prototype weighs 1580 kg, the target...

611 The Hybrid Vehicle

This solution is considered by coauthor Ron Hodkinson to be a short-term remedy to the pollution problem. It has two forms, parallel and series hybrid which he illustrates in Fig. 6.1. Conventionally, parallel hybrids are used in lower power electric vehicles where both drives can be operated in parallel to enhance high power performance. Series hybrids are used in high power systems. Typically, a gas turbine drives a turbo-alternator to feed electricity into the electric drive. It is this type...

622justifying Hybrid Drive

Studies carried out at the General Research Corporation in California, where legislation on zero emission vehicles is hotly contested, have shown that the 160 km range electric car could electrify some 80 of urban travel based on the average range requirements of city households, (a). It is unlikely, however, that a driver would take trips such that the full range of electric cars could be totally used before switching to the IC engine car for the remainder of the day's travel. This does not...

623mixed Hybriddrive Configurations

Coauthor Ron Hodkinson argues that while initially parallel and series hybrid-drive configurations were seen as possible contenders (parallel for small vehicles and series for larger ones) it has been found in building 'real world' vehicles that a mixture of the two is needed. For cars a mainly parallel layout is required with a small series element. The latter is required in case the vehicle becomes stationary for a long time in a traffic jam to make sure the traction battery always remains...

631 The Hybrid Electric Solution For Small Cars

Ron Hodkinson4 points out that US President Bill Clinton's initiative for the American family car sets the target that, in 2003, cars will run for 100 miles on one US gallon of unleaded gasoline. The objectives are reduced fuel consumption, reduced imported oil dependency, and reduced pollution to improve air quality. Can it be done The answer is yes. Work carried out on GM's ultra-lightweight car programme (see Chapter 7) involved composite structure to achieve a body weight of 450 kg, drag...

632 Hybrid Power Pack A Better Solution

In the long term we may use electric vehicles using flywheel storage or fuel cells. Until these systems are available the best answer is to use a hybrid drive line consisting of a small battery, a 45 kW electric drive, and a 22.5 kW engine. This solution would increase the vehicle weight from ENGAGEMENT Electric plate clutch A Manual dog clutch B Clutch A + B Manual lock C ENGAGEMENT Electric plate clutch A Manual dog clutch B Clutch A + B Manual lock C Engine to motor - starting + generation...

635hybrid Passenger Cars

A recent method of construction for permanent magnet motors (Fig. 6.8), by Fichtel & Sachs and Magnet Motor GmbH, exploits the relationship that specific motor torque, on the basis of weight and bulk, is proportional to the product of magnetic field in the air gap, radius of the air gap squared and the axial length of the motor. The requirement for maximum air gap focuses on the construction of the outside of the rotor. On the inside tangentially magnetized permanent magnets are fitted to...

637 Dual Hybrid System

Japanese researchers7 from Equos Research have described the dual system of hybrid drive which differs from the more familiar series-parallel drives and their combinations. It allows free control of the IC engine while keeping mechanical connection between it and the drive wheels a compact transaxle design integrates the two electric drive motors, to simplify the conversion of conventional vehicles, and use of the generator as a motor in combination permits flexible adaptation to driving...

64 Seriesproduction hybriddrive cars

During the early stages of introducing hybrid vehicles into the urban scene, state or local authorities may well offer direct and indirect financial inducements to get these 'clean vehicles' into areas that suffer from atmospheric pollution by motor transport. Now Toyota are manufacturing their Prius, Fig. 6.13, at the rate of 1000 a month and these cars are selling well in Japan. The Japanese Government, in a deliberate effort to curb urban pollution in Japan, is subsidizing the manufacture...

642 Recent Addition To Production Hybrid Vehicles

Honda's Insight hybrid-drive car, Fig. 6.16, uses the company's Integrated Motor Assist (IMA) hybrid system, comprising high efficiency petrol engine, electric motor and lightweight 5-speed manual transmission, in combination with a lightweight and aerodynamic aluminium body, seen at (a), to provide acceleration of 0 to 62 mph in 12 seconds and a top speed of 112 mph, without compromising fuel economy of 83 mpg (3.41 100 km) and 80 g km CO2 (EUDC) emission. The car is claimed to have the...

653 Advanced Hybrid

A joint venture between MAN and Voith has resulted in the NL 202 DE low floor concept city bus, Fig. 6.20, designed to carry 98 passengers at a maximum speed of 70 kph, (a). No steps are involved at any of the entrances which lead directly to a completely level deck height of between 317 to 340 mm. The rear-mounted horizontally positioned diesel engine allows fitment of a bench seat at the rear of the bus it drives a generator with only electrical connection to the Voith transverse-flux wheel...

721 Foamcored Steel Composite Box Beams

The concept of foam-filled box beams, as an extension of sandwich construction, can be seen as an alternative to plastic-steel stabilized core structures with latticed cores. According to Foamseal Urethane Technology, ITW and EASI Engineering3, the results of four-point bending tests replicated by FE analysis, on foam-filled box beams, are showing that optimization based on filled areas and foam densities can achieve given weight, cost, strength and stiffness improvement targets, Fig. 7.2. In...

73 Plastic mouldings for open canopy shells

The RIM process used in Bayer's metal plastic composite construction, described above, also has important potential for production of structural panels for car bodies on a relatively high volume basis. In a punt-type vehicle structure, made from metal box sections stabilized by plastic cores and incorporating rollover hoopframes at the A- and C-posts, open shell sections in RIM polyurethane could be used to form the roof panel, and front rear ends of the body superstructure enclosing windshield...

742 High Strength Laminates Lessons From The Track

The introduction into reinforced thermoset-resin laminates of reinforcements such as carbon fibre and para-aramids, together with epoxy resins, has largely been the preserve of the track race-car builder. Sandwich panels of Nomex honeycomb core materials are also a key ingredient, typically bonded to skins of high strength laminates by an adhesive film such as the Ciba-Geigy Fibredux. For curved surfaces, the core is heat formed at 170-200 C. A key property of this high performance sandwich...

75 Ultralightweight construction case study

The General Motors Ultralite concept car is an encapsulation of advanced carbon-fibre reinforced epoxy resin structure, combined with aerodynamic optimization, that would suit a high-performance electric car. An EC energy saving study6 put forward the forecast of local manufacturing units that would make the hand-building of such vehicles a reality. The study suggests that despite some notable lightweighting initiatives, there is little sign yet of affordable super-light production cars. While...

761 Steel Used Intelligentl Y Leads To Substantial Weight Sa Vings

A car body weight reduction of 25 , without cost penalty, plus a 20 reduction in part count, has been the result of the final phase of the USLAB project for lightweighting steel automotive structures carried out by an international consortium of steel companies supervised by Porsche Engineering Services, Fig. 7.12. The objective of a 'feasible design, using commercially available materials and manufacturing processes', has also been met. The elegant shell at (a) does indeed show some important...

81 Introduction

Both structural and performance efficiencies are considered, in turn, within this chapter which examines first the body-structural shell and second the running gear of the vehicle. The approach to designing for lightweight, recommended in the introductory chapter, is implicit in the design calculation formulae provided for the several aspects of structural design. Second, the optimization of running gear is based on the most efficient exploitation of the special features of electric and...

810 Handling and steering

One of the important attributes for the electric vehicle, if it is to attract drivers from conventional petrol driven vehicles, is responsive handling. While tyres on EVs are required to have minimum rolling resistance there is likely to be some compromise in both ride rate and cornering characteristic, so attention to handling response in design is important. We have considered how drive systems, and the associated electrical equipment need to be arranged in the vehicle so as to balance front...

8102 Electric Steering

Power steering mechanisms using electromagnetic actuation are now being introduced on petrol-driven cars and, of course, are ideally suited to the electric car. Because conventional hydraulic power-assisted steering reduces vehicle efficiency, by drawing power from the engine continuously, energy is wasted by driving the hydraulic pump even when assistance is not required, such as at high cruising speeds on motorways. A typical torque speed curve for a conventional car hydraulic steer-assist...

811 Traction and braking systems

A fundamental trade-off between longitudinal tractive force (or decelerating force in the braking situation) and lateral cornering force, developed at the tyre ground contact patch is central to the balance between traction and stability, Fig. 8.19, of the wheeled vehicle. Road camber or lateral wind forces on the vehicle will rob the tyre frictional force available for traction (or braking) so a knowledge of the magnitude of the interacting forces is necessary in performance prediction...

8113 Electronicallycontrolled Continuouslyvariable Transmission

While in series hybrid-drives batteries and IC engine typically power motor generators, to drive the road wheels, in parallel configured, hybrid-electric IC-engine drive vehicles there is mechanical drive between IC engine and road wheels, usually via continuously variable transmission, Fig. 8.21. A widely accepted CVT is the variable-pitch pulley and belt-drive type originating in the Van Doorne design this transmission heralded the steel drive belt having separate tension and thrust members...

82 Structural package and elements

The trend over the past century has been a move from separate chassis frames and 'panelled' bodies, first to integral and then monocoque construction of road-vehicle body structures - in the interest of light weight and high rigidity. The process has always been frustrated by the demands of conventional occupant-access arrangements and the resulting 'shell' structures are a mass of cutouts whose shapes would horrify an aerospace designer in terms of structural efficiency. It is quite hard to...

821 Box Tubes In Bending And Torsion

While the semi-trailing road tanker is a good example of such a structure, the effectiveness in bending efficiency would relate to the aspect ratio of the box tube and so might not fit the desired relative dimensions of a passenger car. In bending and torsion the tube would be considerably stiffer than most monocoque sedan body designs but careful design of the end ring frames would be necessary, in relation to the cross-section dimensions of the main tube, so as to minimize the tendency to...

84 Optimizing substructures and individual elements

The connection points between the major structural elements (Fig. 8.7) are worthy of detailed attention so that the strength and stiffness of the connected members is preserved at the joint. At a joint between box members such as the important rear quarter to sill junction of a car, (a), consideration should be given to load transfer at the corner. In figures taken from the design of small car body structure, using aircraft thin-walled structural techniques, by T.K. Garrett6, a bending moment...

883rotary Inertia Rolling And Gradient Resistances

While translatory-mass inertia calculation is relatively easy, that of rotary mass is more difficult. It is necessary to sum the rotating inertia of the separate transmission components by relating relative torque to the driving axle as T SIaR2 - for moment of inertia I and angular acceleration a. Since wheel circumferential speed is equal to vehicle translatory velocity, an 'equivalent mass' can be considered as concentrated at the rolling radius - having the same effect on the inertia of...

89 Lightweight vehicle suspension

The ultra-lightweight vehicle presents a special challenge to suspension engineers, for in a 5-seater car the weight of four passengers and luggage at typically 700 lbs is significant compared with the maximum 1120 lb tare weight arbitrarily targeted for a lightweight electric car, with batteries on board. Substantial change therefore occurs in the suspended mass for laden and unladen vehicles. It is, however, an advantage of the near-symmetrical punt-type structure, proposed for the...

About the authors

Electro-technology author Ron Hodkinson is very actively involved in the current value engineering of automotive fuel-cell drive systems through his company Fuel Cell Control Ltd and is particularly well placed to provide the basic electro-technology half of this work. He obtained his first degree in electrical engineering (power and telecommunications) from the Barking campus, of what is now the University of East London, on a four-year sandwich course with Plessey. At the end of the company's...

Agah

Where AG and AH are the changes in Gibbs free energy and enthalpy (both -ve). As a fuel cell does not operate reversibly, the efficiency is given by Rearranging and multiplying numerator and denominator by AG AH gives h -(AG AH)E1 (AG AH)(AH nF) Current density, A cm-2 Fig. 4.2 Voltage current relationship for hydrogen oxygen cell. Current density, A cm-2 Fig. 4.2 Voltage current relationship for hydrogen oxygen cell. Process engineering and control of fuel cells, prospects for EV packages 87...

Cotan 8 cotan 8 TW F FbW and F FaW

Are drift forces which correspond to those required to resist centripetal force of the vehicle as vehicle speed increases and there is a build-up of slip angles. Cornering force (drift force) is also required to overcome thrust due to camber change in roll and differential induced drag caused by outward weight transfer. The latter leads to a torque in the ground plane which must be reacted by increased front- and decreased rear-side forces from the tyres. Also to be reacted are the combined...

Design for optimum bodystructural and runninggear performance efficiency 205 823 Avoiding Shear Buckling

The assumption of panels being infinitely stiff in shear would require that the panels were stabilized in some way to avoid buckling under shear force, recognizable by diagonal creasing, easily demonstrated on a stiff sheet of paper. In conventional practice this is achieved by pillars, rails and or swages which divide up a vehicle sidewall, for example as in the view at (c, left), into panels which are small enough to avoid the possibility of buckling. The pioneering aircraft structural...

Gmax RrT 4RriTe Wg IwrI12

Where motion resistance R R + R and I and I are engine and wheel inertias. Engine speed relates to vehicle speed as V 2pN r. 3600 12 . 60EG . 5280 Nr 168GE and tyre slip efficiency E can be assumed equal to 0.965 for this calculation. Thus Ne and Te for each gear reduction may be tabulated against road speed by means of the engine torque speed curve. Motion resistance forces are subtracted from P to give free tractive Fig. 8.17 Hydragas suspension (a) interconnection system (b) automatic...

Lightweight Electric Hybrid Vehicle Design

OXFORD AUCKLAND BOSTON JOHANNESBURG MELBOURNE NEW DELHI Linacre House, Jordan Hill, Oxford OX2 8DP 225 Wildwood Avenue, Woburn, MA 01801-2041 A division of Reed Educational and Professional Publishing Ltd A member of the Reed Elsevier plc group Reed Educational and Professional Publishing Ltd 2001 All rights reserved. No part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or...

Preface

The stage is now reached when the transition from low-volume to high-volume manufacture of fuel cells is imminent and after an intense period of value engineering, suppliers are moving towards affordable stacks for automotive propulsion purposes. Since this book went to press, the automotive application of fuel cells for pilot-production vehicles has proceeded apace, with Daewoo, as an example, investing 5.9 million in a fuel-cell powered vehicle based on the Rezzo minivan, for which it is...

References

Hodkinson, R., 45 kW integrated vehicle drive, EVS 11, Florence, 1992 2. Hodkinson, R., Machine and drive characteristics for hybrid and electric vehicles, ISATA 29, Stuttgart, 1996 3. Hodkinson, R., Towards 4 dollars per kW, p. 4 etseq, EVS 14, Orlando, December 1997 4. Hodkinson and Scarlett, Electric Vehicle Drives, Coercive Ltd report, December 1991 Electric vehicle technology, bound volume of SAE papers, 1990 Electric and hybrid vehicle technology, bound volume of SAE papers, 1992 Electric...

T2[AgSdst [T4bd2Gbt1 dt2 dt3 dt4

For the transition from a closed to an open section, shown at (c), the open section can be seen as a limiting case of the closed tube as it collapses. Transverse shear stress distribution has an important effect on the torsional rigidity of the cross-section, the closed tubes resisting torsion by the area of the cross-section enclosed by the mean thickness of the wall. Shear flows around an elemental section of the wall, (d), are equal and constant and by integrating along the section...

Y 1 MM 1 [SIJMr2 SIRVT2

Where SI is wheel inertia and I is that for 'engine speed' parts and typically Y 1 + (0.4 + 0.0025R2) Rolling resistance R can be expressed as a dimensionless coefficient f ( 0.013 for radial tyres) while transmission resistance is obtained from a summation of the power consumed at various stages along the powertrain. Overall efficiency E depends on the transmission system and is conventionally assumed as E 0.90 in direct drive and 0.85 in lower gears. Air resistance is obtained from

44 Thermodynamics of fuel cells

The efficiency of the heat engine is limited by the Carnot cycle and equals A Carnot efficiency of about 70 could be achieved theoretically with upper and lower temperatures of1000 K and 300 K, which would require a compression ratio of about 20 1. However, fuel and material restrictions limit the practical efficiency to about 50 , which is achieved by modern, large, low speed diesel engines, but automotive gasoline and diesel engines achieve much lower efficiencies, particularly when averaged...

636 Taxi Hybrid Drive

Based on a Range Rover, an EC project involving Rover, gas turbine makers OPRA, Athens Technical University, Hawker Batteries and Renault was carried out at Imperial College so as to provide a hybrid powertrain for a European taxi, Fig. 6.10, and in particular the development of a turbogenerator. A system involving a gas turbine and high speed generator together with a small battery pack for power storage and zero-emission city driving in a series configuration has been proposed by the EC and...

83 Punttype structures

The optimally efficient shell-beam structure, typified by an aircraft fuselage, is argued above to fit a relatively limited range of automotive body configurations. It also requires radical solutions to the mounting of wheel suspension and drive systems to the end bulkheads or ring frames, particularly so pending the development of lightweight wheel motors with low enough mass to keep unsprung weight within reasonable bounds for ultra-light vehicles see Section 4.7.2. Where conventional...

824 Sandwich Construction For Panel Stability

In determining preferred dimensions and properties of the sandwich panels in terms of the face and core materials, advantage again can be taken of pioneer work used in aircraft structural analysis. Choice of skin and core modulus, density and sustainable working stress is made so that the lightest possible panel is stable with respect to the external loading, Fig. 8.4. Aircraft designers found that the most elaborate 'sheet stringer' construction was only able to stabilize a panel up to 50 of...

523 Nickelmetal Hydride

As recently specified as an option on GM's EV1, the nickel-metal hydride alkaline battery, Fig. 5.3, was seen as a mid-term solution by the US Advanced Battery Consortium of companies set up to progress battery development. According to the German Varta company, they share with nickel-cadmium cells the robustness necessary for EV operation they can charge up quickly and have high cycle stability. The nickel-metal hydride however, is superior, in its specifications relative to vehicle use, with...

87Case study of FEA for EVs and structural assemblies

Daewoo's DEV3 electric vehicle has used structural analysis techniques applied by the Institute for Advanced Engineering in the design of its space frame7. The frame comprises welded extruded aluminium alloy members of identical cross-section and the design was optimized by setting up design variables for each member in differential element thicknesses. The structure incorporates a large battery tray over the floor area, the design of which was also optimized such that a lightweight EV build...

333motor Design Factors Affecting Machine Efficiency

For the stator the important factors are (i) shape of lamination - optimized lamination has a much larger window than 50 Hz induction motor lamination and a bigger rotor diameter relative to the stator diameter (ii) use of high nickel steels is counteracted by poor thermal conductivity. Thin silicon steel with well-insulated laminations gives best results. Laminations should be annealed and not subjected to large mechanical stresses. The core can be a slide fit in casing at room temperature as...

812 Lightweight shafting CV jointing and road wheels

Between the CVT and the tyre ground contact patch, there is considerable scope for weight saving and the reduction of rotational inertia in the drive-line. A development programme by GKN has led to substantial weight reductions in most elements of the drive-line for front-, rear- and all-wheel drive systems, Fig. 8.22. Reduction in weight has also had a knock-on effect in obtaining increased whirling speeds and therefore the ability to have prop-shaft UJs without the risk of vibration problems....

3710 Control Circuit In Battery Charging Mode

The control circuit for battery charging is shown in Fig. 3.20. When the battery is below 2.1 V per cell and 40 C it is charged at the maximum current obtainable from the supply. Above 2.1 V cell the battery is operated at reduced charging up to 2.35 V per cell, compensated at -4 mV C for battery temperature. This data assumes lead-acid cells. As can be seen from the block diagram there are two separate loops for the buck and shunt choppers. The fast current loops stabilize the transfer...

86 Finiteelement analysis FEA

This computerized structural analysis technique has become the key link between structural design and computer-aided drafting. However, because the small size of the elements usually prevents an overall view, and the automation of the analysis tend to mask the significance of the major structural scantlings, there is a temptation to by-pass the initial stages in structural design and perform the structural analysis on a structure which has been conceived purely as an envelope for the...