KERS Electric Aims to Produce Electricity by a Motorcycle

8/2/2019 KERS Electric Aims to Produce Electricity by a Motorcycle

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KERS Electric aims to produce electricity by a motorcycle - electric

generator (MGU Motor Generator Unit). This device can beconnected directly to the transmission shaft parallel to the exchange

or through a cascade of gear reducers. The latter solution is very

complex because all the teams that use the electric KERS haveturned to the positioning of the MGU in front of the traditional

combustion engine. The conversion of kinetic energy into electricity

occurs when the driver operates the brake pedal to certainpressures, previously calibrated and operated by the ECU.

When the car stops (or release the gas), in fact, the moto-alternator, through a system of hydraulic clutches, it should be

taken in the crankshaft. Under normal conditions, the motion -

alternator have to be disconnected, otherwise there would be a loss

of power, as well as producing harmful friction.

During braking, so the dynamo acts as MGU (such as the alternatorof the car as standard). The energy produced is stored in lithium

batteries, the combination of which is defined HVB (Hight Voltage

Battery Pack).

When the pilot will require the extra power, just press a button on

the steering wheel. In this phase, the MGU is no longer acting as

alternatives but as a driver - electric, going back into socket on thecrankshaft or transmission and returning the energy stored earlier.

In this phase, electrical energy is converted into mechanicalenergy.

The pilot will use the extra power, at once per revolution (80 Cvcontinued for 6.67 s), or modulate it and divided several times as it

sees fit. The "boost" is also operated during the start, but notimmediately turning off the red light. In fact, the system can load

and release energy at speeds above 100 km / h.

KERS Electric, according to unofficial sources, works at 400 V and

700 - 800 A and weighs all-around 25 -30 kg This weight, it will add

weight to the minimum required by regulation (605 kg). Therefore,

technicians, must ensure, before the stay KERS to lighten the carand explore a new weight distribution.

The idea of KERS is certainly interesting, but not in the 2009 season

was a huge success. The strong regulatory limits have the potentialto partially castrated, facilitating the task of those teams that have


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focused sull'esasperazione aerodynamics, ricunciando immediately

to the development of KERS, since the use was optional in 2009. Itis no coincidence that Brawn and Red Bull Racing, who have fought

for the world title, has never used energy recovery, while Ferrari,

McLaren, Renault and BMW have invested significant funds. Fromthe first track tests reveal any problems of reliability and security

that had led the Toyota not to venture on this terrain, since the

Nissan was that the market was leading the series hybrid cars anddid not want a problem F.1 could reflect negatively on sales. In the

first test of a BMW mechanic was struck by a burst of eddy currents.

and so, mechanics, technicians and road marshals were equippedwith special insulating gloves to avoid the violent eddy currents. The

trouble with security, in fact, had been cleverly solved, but the

nearly 40 kg at the beginning that the system weighed heavily

conditioned performance, which were not offset dall'overboostpower available in a limited time too.

E 'right to ask questions and go on KERS understand what were the

problems to be solved.

The system, as mentioned earlier, was composed of three elements:

the motor-generator that functioned as an alternator and electric

motor, lithium batteries and electronic control unit. The motor

generator unit (MGU), during deceleration, worked as a generator,producing electricity that was stored in batteries, waiting for the

driver to download the extra power during acceleration. In this case,the MGU, powered by batteries, operated by an electric motor, in

sync with the combustion, contributing to the car's performance.

There was also a special unit that handles all these steps.

Williams, however, had experienced an electro-mechanical systeminstead of the motor generator. The Williams system, the lighter of

the electrical system, instead of the lithium battery has a carbon-

fiber flywheel which rotates in a crankcase vacuum to reduce

friction. The fly, which works usually coupled to an electric motor, is

expected to reach speeds well in excess of 40.000/50.000 rpm, or

even close to 100 rpm. In this system, the stored energy duringdeceleration is stored in the form of kinetic energy. In practice, this

device, on the principle of the old machines toy "friction" (those that

are charged by spinning the wheel and then release them and makethem run on the floor of the house) inside which there was flying

(rather heavy), which Once activated, released its kinetic energy to

the transmission shaft connected to the wheels.


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The engineers had decided to install it between the engine and the

body, in a critical area of the car, surrounded by the fuel tank. KERSweighed around 35-40 kg, a mass that was not added to the

minimum weight of F1 (this weight but was added by the Technical

Regulations of 2011). The technicians who worked on it, you haveless ballast to help find the perfect car balance with a proper weight

distribution. The plant not only had the handicap of weight, but also

that of the volume: the mass of the KERS car has heavily influencedthe design of the car. Ferrari's engineers are able to put all the STTA

system in a suitcase the size of a 48 hours, and time are STTA

made important steps in the miniaturization of parts. The first MGUweighed about 6 / 7 Kg: permanent magnet synchronous motor

turning speed operation of the V8 petrol: 18,000 rpm. Doubling the

speed to 36,000 rpm, the mass had fallen by one third, making it

necessary, however, in coupling a clutch between the two powerunits (electric and gasoline).

Ferrari and McLaren have benefited from the KERS at the start:

these cars have often won the position at the start thanks

all'overboost (worked over 100 km / h).

The difficulties that had emerged during the season was the

charging of lithium batteries and their cooling: in fact, to ensure

proper cooling, it had come to a real cooling system. GP in thehottest of the difficulty was to recover all the energy needed to have

a sufficient boost, as it varied greatly depending on the shape of thetrack and the number of detached. The rule, in fact, limited the use

of acceleration energy of 400 kJ, but did not prevent a greater

storage batterie.Siccome in the performance of the system did notexceed 50% for 400Kj used, it was necessary to dispose of more

than 800. Each time they failed to reach the threshold, the morepower for 6.6 s, there was 80 hp, but less and less. The Ferrari

seems to have never suffered from this problem but the McLaren is,

just because the batteries were working in a narrow temperature

range. If the battery was too cold not broke, but had too high an

internal resistance, so it was not efficient, but it was too hot lost in

performance lap after lap. The ideal was to make it work in a rangebetween 75 and 85 degrees, while the electric motor and the

electronic control unit could easily withstand the temperatures of

the engine, close to 120 C. In mass production there were nobatteries to meet the demands of F1 and years of research in the

Circus will certainly contribute to the development of new batteries

for the market. And the KERS could become a useful tool not only toincrease performance but also in reducing fuel consumption.


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When (or if) we watch a Formula One race on television this year, the commentators will

probably talk about the KERS system, and how (or if) it is being used. The KERS units have

yet to attain the same impressive level of reliability of the highly stressed internal combustion

engines used alongside them. This is hardly surprising; we understand combustion engines

pretty well after having developed them for more than 130 years, and modern race engines,

in series where regulations are essentially static, have incrementally increased performance

and solved any reliability problems as they occur.

There are three main subsystems of the electric KERS systems used in Formula One - the

electric motor/generator, the power electronics and the battery. The battery, for both hybrid

and pure electric production vehicles, holds the key to producing a light, affordable vehicle.

In racing, where the mass of the car is lower and the packaging of major components is

critical, the battery represents something that not only has a critical effect on the output of

the combined engine/KERS unit but also on the design of the rest of the car. The Red Bull

Formula One car this year would not compromise the design of the rest of the car in order to

package the KERS system, and this has given the team KERS reliability headaches

throughout the season.

The battery is made up of multiple cells, connected in series to give the system voltage. They

are thought to be exclusively based on lithium ion technology, with each cell giving about 3.6

V output. With systems operating at hundreds of volts in order to limit maximum currents,

there can be hundreds of cells in a typical KERS battery. The current 60 kW discharge limit,

for a 100-cell battery, would result in an average current draw of about 160 A, with peak

currents being higher than this.

I asked battery expert Nigel Vincent of ABSL Power Solutions, which makes lithium ion cells,

about various aspects of the cells and their development. He explained that there is a trade-


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off between energy density (the amount of energy stored per kilogramme of cells) and power

density (the charge/discharge power per kilogramme of cells), with differing chemistries

offering different advantages.

Lithium ion cells based on LiMnO2 (lithium manganese oxide) and LiFePO4 (lithium iron

phosphate) show high power density, but lack energy density compared to newer mixedoxide cells which have excellent energy densities (>225 Wh/kg). These lithium ion

chemistries concern the cathode but changes in anode chemistry, according to Vincent, could

yield further significant increases in specific energy. Moving away from graphite anodes to

ones based on silicone or titanate could see energy densities reaching 350-400 Wh/kg in the

next five to ten years.

The other important metric against which batteries are judged is the charge/discharge rate,

and this is limited, otherwise damage can be caused. This limiting rate is affected by the

construction of the cells, with features such as electrode surface areas being important

factors, as well as the chemistry being used.

Of great importance in a race application is not only the consideration of energy/power

density but also space efficiency. Traditional cylindrical cells are being displaced to a certain

extent by pouch cells, which are essentially flat and can therefore be packaged more

efficiently.

Developments in cell chemistry and manufacturing have also improved the operating life of

the cells we might choose to use for race hybrid systems. Other factors affecting cell life, as

discussed with Vincent, are said to be the depth of charge/discharge, rate of

charge/discharge, charge voltage and ambient temperature.

The advent of KERS in Formula One and hybrids in other forms of racing will, hopefully, help

drive forward advances in cell chemistry and construction for the benefit of racing and also

for production hybrids in future.


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Fig. 1 - The pouch cell offers packaging advantages over traditional cylindrical cells

(Courtesy of ABSL Power Solutions)

Fig. 2 - A traditional cylindrical lithium ion cell (Courtesy of ABSL Power Solutions)

I asked about the advantages of a purely electrical system compared to a mechanical system,and the main advantage stated was the flexibility in packaging, and owing to the modular

nature of the energy storage, adding extra capacity is simple matter. There is no requirement

to have all the energy storage in one place, so mass distribution can be easily tailored to suit

the needs of the chassis. One major disadvantage was said to be the transport of the

batteries and the cars because of the high voltages involved and the precautions that need to

be taken to comply with regulations for air freight and so on.

The electric motor-generator unit (MGU) shown in fig. 1 is a liquid-cooled synchronous motor,

using permanent magnets. It is geared at a fixed ratio of about 2:1 to the crankshaft speed,

and we can therefore expect maximum speeds of about 40,000 rpm for the MGU.

KERS

ABSTRACT

In the past decade of the modern car era attempts at inducing Alternative Technology in cars had

been made with some amount of success. This gave birth to cars that ran on Electric, Hybrid and

Fuel cell technology. Though these cars are present in the market they have failed to make a

significant difference as people still prefer gasoline fuelled cars. In 2009 FIA had introduced a

row of technical changes to the sport also permitting the teams to run regenerative technology

called KERS in an attempt to win back the fans interest and to prove that F1 does care about the

environment. The technology already existed in hybrid cars but the primary purpose behind itsintroduction was to develop an efficient technology that could be transferred to road cars. All the

major factory teams came equipped with KERS system but all of them struggled through the first

half of the season many even avoiding it after three races due to reliability issues. The ban on

testing made developments harder and time consuming. The KERS equipped cars won only

three races in the entire season with the first win coming late after mid season. Even after

investing huge amount of resources and money on KERS the teams failed to get the best out of

the system. In this report the various KERS technologies developed by the F1 teams like electric,

flywheel and electromechanical based KERS units and similar systems present in road cars

along with their pros and cons are discussed in brief. Apart from the above, which system has

more potential to be inducted in road cars is also discussed.

INTRODUCTION

I do agree that KERS in F1 would benefit the mainstream motor industry given the fact that one

of the primary reasons behind its introduction was to facilitate a smooth transfer of the

technology to road cars though substantial amount of work needs to be done. The 2009 F1

season introduced the widest range of technical rule changes the sport had witnessed for more

than a decade. The one specific topic that got significant attention both from the F1 teams and

the media was KERS a device which stores the waste energy produced during braking and

releases it during acceleration. The rules limited the amount of energy recovery of KERS to

400kJ per lap, giving an extra 80hp for about 6.5 seconds. The teams were allowed to apply any


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means with the condition that they pass the F1 safety standards. After months of research and

development the teams came out with innovative ideas but it was evident that the field was

divided into two types. Williams was the only team which developed a mechanical flywheel based

KERS unit, though they never used it in a race while the rest of the field went for electric KERS

unit. In contrast to what most people believe KERS is not a new technology in fact it has beenused in a variety of applications including hybrid buses and cars. We shall now study both the

systems and the improvements they can bring to the automobile industry.

KERS in F1 cars

As in any hybrid vehicle the primary factor that limits the efficiency gains over its lifetime is the

recoverable energy storage system (RESS). The two most important characteristics of any RESS

are specific energy and specific power. The former refers to the amount of energy per kilogram

that the system can store and the latter to the rate at which energy can be put into or taken out of

the system per kilogram. In the wake of preparations for the 2009 season teams had tested a

range of different systems including electric, mechanical, hydraulic and even pneumatic basedKERS units. After careful analysation majority of the teams concluded that the electric system

would be the best option that would deliver the required amount of energy from the brakes. The

norm in F1 to make things as compact and light as possible led the teams to this decision. With

the rules allowing the teams only 60Kw of energy for 6.5 seconds per lap, drivers had to be very

wise with regard to using this extra power. The KERS system was primarily intended to aid the

overtaking of cars but as seen throughout the season most of the KERS equipped cars lacked

overall pace at the start of the season and used the KERS for better acceleration out of the

corners and to defend their positions. The basic working of the kers unit in F1 cars is very similar

to the ones in hybrid road cars.

ELECTRIC KERS

This system consists of three components, the mototr/generator; KERS control unit and the

battery pack. The motor/generator is directly connected to the drive train. It produces electrical

energy during braking and releases it back through the transmission when required. The energy

captured is stored in the battery which in turn is connected to the Kers control unit that governs

the release and storage of energy to and from the batteries. The motor/generators were provided

by motorsport company's specialising in this field eg. Magnetti Marelli (supplied for

Ferrari,Renault,Toyota,RedBull), Zytek ( Mclaren) who worked closely with the teams to

manufacture motor/generators tailor made to suit their design requirements. The heat generated

during the charging and discharging process hampers the performance of the motors, hence the

motor has an integrated liquid cooling system which weighs just 4kgs in total. The RESS unit

(battery) has been developed by the teams themselves and Lithium-ion was the preferred choice.

The entire system including the motor/generator, Kers control unit and the batteries weighs

around 25-35 kgs with 25.3 kgs being the lightest developed by Zytek for the Mclaren Mercedes

team.

ADVANTAGES OF ELECTRIC KERS

The electric systems allow the teams to be more flexible in terms of placing the various

components around the car which helps for better weight distribution which is of vitalimportance in F1.


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The specific energy of Lithium-ion batteries in comparison is unrivalled as they can store

considerably more energy per kg which helps reduce the size

DISADVANTAGES OF ELECTRIC KERS

Lithium-ion batteries take 1-2 hours to charge completely due to low specific power (i.e

rate to charge or discharge) hence in high performance F1 cars more batteries are

required which increases the overall weight of the batteries.

Chemical batteries heat up during charging process and this takes place a number of

times in KERS units which if not kept under control could cause the batteries to lose

energy over the cycle or worse even explode.

The specific power is low as the energy needs to be converted at least two times both

while charging or discharging causing energy losses in the process.

REFERENCE

1. Vehicle Propulsion System by Prof. Lino Guzzella, Dr.Antonio Sciarretta, ETH Zurich,

Institut fur Mess-und Regeltechnik, Sonneggstr.3, 8092 Zurich Switzerland. 2005 page (

87-106) and (124-130).

2. Handbook Of Automotive Powertrain & Chassis Design by John Fenton 1998 page (131-

139).

3. http://www.racecar-engineering.com/articles/f1/426958/exclusive-mclaren-f1-kers.html.

4. Flybrid Systems LLP http://www.flybridsystems.com/Technology.html

5. High Speed Flywheel Based Hybrid System For Low Carbon Vehicles by D.Cross, J.Hilton

from IEEE Xplore Oxford Brookes University.

6. TorotrakPlc.

http://www.torotrak.com/Resources/Torotrak/Documents/SAE_WC_2009_09PFL-0922_KERS.pdf

7. Williams Hybrid Power Lt. http://www.williamshybridpower.com/technology/

The introduction of Kinetic Energy Recovery Systems (KERS) is one of the most

significant technical introductions for the Formula One Race. Formula One have

always lived with an environmentally unfriendly image and have lost its relevance to

road vehicle technology. This eventually led to the introduction of KERS.

KERS is an energy saving device fitted to the engines to convert some of the waste

energy produced during braking into more useful form of energy. The systemstores the energy produced under braking in a reservoir and then releases the

stored energy under acceleration. The key purpose of the introduction was to

significantly improve lap time and help overtaking. KERS is not introduced to

improve fuel efficiency or reduce weight of the engine. It is mainly introduced to

improve racing performance.

KERS is the brainchild of FIA president Max Mosley. It is a concrete initiative taken

by F1 to display eco-friendliness and road relevance of the modern F1 cars. It is a

hybrid device that is set to revolutionize the Formula One with environmentallyfriendly, road relevant, cutting edge technology.


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Components of KERSThe three main components of the KERS are as follows:

An electric motor positioned between the fuel tank and the engine is connected

directly to the engine crankshaft to produce additional power.

High voltage lithium-ion batteries used to store and deliver quick energy.

A KERS control box monitors the working of the electric motor when charging andreleasing energy.

A Electric motor

B Electronic Control Unit

C Battery Pack

Working Principle of KERS
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Kinetic Energy Recovery Systems or KERS works on the basic principle of physics

that states, Energy cannot be created or destroyed, but it can be endlessly

converted.

When a car is being driven it has kinetic energy and the same energy is convertedinto heat energy on braking. It is the rotational force of the car that comes to stop

in case of braking and at that time some portion of the energy is also wasted. With

the introduction of KERS system the same unused energy is stored in the car and

when the driver presses the accelerator the stored energy again gets converted to

kinetic energy. According to the F1 regulations, the KERS system gives an extra 85

bhp to the F1 cars in less than seven seconds.

This systems take waste energy from the cars braking process, store it and then

reuse it to temporarily boost engine power. This and the following diagram showthe typical placement of the main components at the base of the fuel tank, and

illustrate the systems basic functionality a charging phase and a boost phase. In

the charging phase,

kinetic energy from the rear brakes (1)

is captured by an electric alternator/motor (2),

controlled by a central processing unit (CPU) (3),

which then charges the batteries (4).


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In the boost phase, the electric alternator/motor gives the stored energy back to the

engine in a continuous stream when the driver presses a boost button on the

steering wheel. This energy equates to around 80 horsepower and may be used for

up to 6.6 seconds per lap. The location of the main KERS components at the base of

the fuel tank reduces fuel capacity (typically 90-100kg in 2008 ) by around 15kg,enough to influence race strategy, particularly at circuits where it was previously

possible to run just one stop. The system also requires additional radiators to cool

the batteries. Mechanical KERS, as opposed to the electrical KERS illustrated here,

work on the same principle, but use a flywheel to store and re-use the waste

energy.

Types of KERSThere are basically two types of KERS system:Electronic KERS
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Electronic KERS supplied by Italian firm Magneti Marelli is a common system used in

F1 by Red Bull, Toro Rosso, Ferrari, Renault, and Toyota.

The key challenge faced by this type of KERS system is that the lithium ion battery

gets hot and therefore an additional ducting is required in the car. BMW has usedsuper-capacitors instead of batteries to keep the system cool.

With this system when brake is applied to the car a small portion of the rotational

force or the kinetic energy is captured by the electric motor mounted at one end of

the engine crankshaft. The key function of the electric motor is to charge the

batteries under barking and releasing the same energy on acceleration. This electric

motor then converts the kinetic energy into electrical energy that is further stored in

the high voltage batteries. When the driver presses the accelerator electric energy

stored in the batteries is used to drive the car.

Electro-Mechanical KERSThe Electro-Mechanical KERS is invented by Ian Foley. The system is completely

based on a carbon flywheel in a vacuum that is linked through a CVT transmission

to the differential. With this a huge storage reservoir is able to store the mechanical

energy and the system holds the advantage of being independent of the gearbox.

The braking energy is used to turn the flywheel and when more energy is required

the wheels of the car are coupled up to the spinning flywheel. This gives a boost in

power and improves racing performance.

Limitations of KERSThough KERS is one of the most significant introductions for Formula One it has

some limitations when it comes to performance and efficiency. Following are some

of the primary limitations of the KERS:

Only one KERS can be equipped to the existing engine of a car.

60 kw is the maximum input and output power of the KERS system.

The maximum energy released from the KERS in one lap should not exceed 400 kg.

The energy recovery system is functional only when the car is moving.

Energy released from the KERS must remain under complete control of the driver.

The recovery system must be controlled by the same electronic control unit that is

used for controlling the engine, transmission, clutch, and differential.

Continuously variable transmission systems are not permitted for use with the

KERS.

The energy recovery system must connect at one point in the rear wheel drive train.

If in case the KERS is connected between the differential and the wheel the torque

applied to each wheel must be same. KERS can only work in cars that are equipped with only one braking system.


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E-KERS forms part of the power transmission of F1 cars. It converts kinetic energy won during thebreaking process into electricity with the help of an electric motor that also performs as agenerator. This power is stored in lithium-ion batteries and fed back into an electric motor in strictlyregulated quantities, which in turn boosts the Formula 1 car's combustion engine duringacceleration periods. Isabellenhtte's IVT-F integrated current sensor controls the quantity ofpower supplied by the E-KERS. The Formula 1 umbrella organisation FIA aims to ensure in this

way that the racing teams will not use E-KERS to break the rules. According to the sensor maker,It took just two months to develop the modules though they are specifically designed for use inFormula 1.

The sensor measures current, voltage and temperature through different channels at a rate of 3,5kilosamples per second. It provides fixed calculation of mean value over 16 sampling values andprovides the output data across a CAN bus interface at a data rate of up to 1 MBit/s. Operating lifetime is adequate to Formula 1 requirements with 2000 km (minimum).

Our know howis in the electrical side, explains Roberto Dalla, head of motorsport at the

Italian firm. We have lots of experience in alternators and electric motors, whilst we do

not have a lot of experience in flywheels or other systems. We feel that the battery side of

development is improving all the time. In the future, the scope for development of

electrical systems is greater. Despite this, Dalla does not completely dismiss other

approaches. With the flywheel system, we were surprised by the dimensions and

performance. The hybrid of the two systems, with a flywheel as the storage medium and

the motor as a driver, could be an interesting possibility for the future. Up to this point,

though, we feel our approach is correct, but only the future will show if we are right or

wrong.

THE THREE ELEMENTS

The Magneti Marelli system can be broken down into three distinct components. The first

element is a motor/generator attached directly to the cars drivetrain. This generates

electrical energy under braking and then releases it back into the transmission when

required. This, in turn, is linked to an intelligent electronics control unit that controls both

the release and capture of energy by the motor/generator and also the flow of energy toand from the third element, the batteries. Initially, Dallas team decided to develop all


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three components in-house, but the specific demands of Formula 1 changed this

approach, as he explains: In the beginning, when we decided to develop this device, we

were aiming to provide a turn-key system, including a battery. However, we quickly

decided that the battery design is very closely related to what the teams want to do, how

to place it in the car, and how much of a compromise in terms of dimensionalperformance the team is willing to accept. So we gave the teams the option to use their

own battery. Most will use a lithium ion battery, but the system also has the ability to be

connected to a super-capacitor.

The motor/generator, as is to be expected from a manufacturer with the expertise of

Magneti Marelli, is a very compact unit, weighing in at approximately 4kg. Its output is in

line with FIA specifications limiting power to 60kW, and the energy stored each lap to

400kJ, with the system optimised to handle this level of performance. It features a

synchronous motor with permanent magnets, managed by an electronic control unit. Due

to the heat generated during the charging and discharging process, the motor has an

integrated liquid cooling system a fact teams are having to address, given the lack of

cooling apertures allowed under the 2009 regulations.

With the only obvious cooling solutions available to designers carrying an inevitable drag

penalty, Dalla aimed to find a good balance between cooling requirements and power

delivery. It justifies the extra demands placed on the other systems. We are managing

60kw of power with imperfect efficiency, so there are thermal issues. This means the

teams will have to choose the solution that best suits their needs. The more efficient the

systems become, the less the demand is placed on the cooling systems.

One of the biggest problems both teams and KERS manufacturers have to address is

how to package inherently bulky electrical systems within the tight confines of a modernFormula 1 car.

A typical electric KERS F1 configuration locates the electric motor in front of the ic engine, connected via a

small shaft spur-geared to the front of the crankshaft. The shaft, turning at crankshaft speed, must be

instrumented to measure torque, which can be in either sense: driving (positive) when the electric motor

adds torque to the engine, and generating (negative) when the road wheels back-drive through the

powertrain and engine to the electric motor which in turn creates a substantial braking effect on the car.

It was at this point in early 2008 that Transense Technologies were invited to propose a KERS F1 torque

sensing system comprising hardware, interrogation electronics and application software.

A 2009 spec F1 engine running at up to 18,000 rpm will generate very high centripetal accelerations,

acting inwards, on a sensor mounted on the shaft surface approaching 4000g for the shaft in question.

This means that a force equal to 4000 times the weight of the sensor acts outwards trying to tear it away

from the shaft. In addition engine vibrations are intense, circa 100g, while operational temperatures range

from 70 to 170C.

Transense employed their surface acoustic wave (SAW), quartz substrate, dual and triple resonator sensors

to opposing sides of the shaft within a hermetically sealed cavity. A non-contacting radio frequency (RF)

rotary coupler provided two way signal connection between sensors and miniaturised interrogation


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electronics located within the electric motor power electronics and control box.

Software, which analyses the RF signals using a Discrete Fourier Transform (DFT) algorithm to generate

independent torque and temperature signals with 3 kHz update rate, together with further code enabling

the FIA to check that performance of the KERS torque system stayed within their requirements, was alsoprovided by Transense.

Static torque measuring performance (linearity, repeatability, hysteresis, creep and rotation) was

established initially at Transense laboratories near Oxford. Typically at 120C, the combined errors were

less than 1% of full scale.

A string of 3 F1 KERS shafts being calibrated within an environmental chamber over the full operational

range of torque and temperature

Development proceeded in close co-operation with the electronics and engine suppliers to the F1 race

team. Visits from FIA technical representatives were made to understand SAW technology and to ensure

that company systems were in place to provide software version control and retrospective traceability.

Dynamic testing, at the engine manufacturers facility, were carried out on both electric and engine

dynamometers. The acid test on the actual racecar followed.

Manufacturing and calibration of KERS shafts including bonding of quartz dies, gold wire interconnects,

hermetic sealing and calibration to meet the 2009 seasons requirements were completed at Transense.


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Clarence Pilgrim carries out gold wire bonding operations on an F1 KERS shaft in the Class 10,000 clean

room

In a typical race weekend, F1 cars run 2 practice sessions, 1 3 qualifying sessions and the race itself,

totalling up to 500 miles. As the 2009 season closes, Transense have supplied one race team with torque

sensing systems throughout, which have enabled it to demonstrate the benefits of kinetic energy recovery

and to make some exceptional passing manoeuvres!

KERS layout and functionality charging phase


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Kinetic Energy Recovery Systems, or KERS, become optional for 2009. Such systems take

waste energy from the cars braking process, store it and then reuse it to temporarily boostengine power. This and the following diagram show the typical placement of the maincomponents at the base of the fuel tank, and illustrate the systems basic functionality a

charging phase and a boost phase. In the charging phase, kinetic energy from the rear

brakes (1) is captured by an electric alternator/motor (2), controlled by a central processingunit (CPU) (3), which then charges the batteries (4).

KERS layout and functionality boost phase


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In the boost phase, the electric alternator/motor gives the stored energy back to the engine

in a continuous stream when the driver presses a boost button on the steering wheel. Thisenergy equates to around 80 horsepower and may be used for up to 6.6 seconds per lap. Thelocation of the main KERS components at the base of the fuel tank reduces fuel capacity

(typically 90-100kg in 2008 ) by around 15kg, enough to influence race strategy, particularly

at circuits where it was previously possible to run just one stop. The system also requiresadditional radiators to cool the batteries. Mechanical KERS, as opposed to the electrical KERS

illustrated here, work on the same principle, but use a flywheel to store and re-use the wasteenergy.


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Confident that they could create a motor/generator unit to the required specification,

Magneti Marelli concentrated the majority of its development effort on reducing the size

and weight of the ECU and the ancillaries. Whilst it is larger than most control boxesfound in a grand prix car, Dalla believes it is still very compact in relation to the levels of

current and load it is required to handle.

KERS Principle:

The Kinetic Energy Recovery System (KERS) stood out as one of the biggest changes of 2009. With

such huge forces in Formula One, the cars contain a very large amount of waste energy, especially

under braking. A KERS, however, recovers a large proportion of this wasted kinetic (movement)

energy from the brakes and stores it in batteries. The energy in the batteries is then used to boost

existing engine power to give the driver extra horsepower.

The KERS system


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How a KERS works:

A standard KERS operates by a charge cycle and a boost cycle. As the car slows for a corner, an

electric motor (or alternator) captures the waste kinetic energy from the rear brakes. This collected

kinetic energy is then passed to a Central Processing Unit (CPU) and onto the batteries. The batteries

sit underneath the drivers seat and are positioned centrally to minimise the impact on the balance of

the car. Due to the high voltage of the batteries, Shell has developed a bespoke fluid that insulates

and cools the batteries to ensure the safety of the system in the Ferrari F60.

When the driver presses the boost button on the steering wheel, the batteries transfer the stored

energy back to the engine for a maximum of 6.67seconds per lap. This extra energy contributes

around 80hp and can shave up to four tenths off a lap time.

How KERS works

Why run a KERS?


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