F1 2014 tech: A new era of ERS

In the second part of AUTOSPORT technical writer Craig Scarborough's four-part series on Formula 1's 2014 rules revolution, he explains the new era of energy recovery systems and why they are set to play a huge role.

In addition to the new turbo engine, energy recovery systems will become a a far greater part of the performance equation for Formula 1 cars in 2014.

There will now be two types of such systems, which will provide over 160hp for most of the lap.

This technology comes with huge challenges for the engineers, driver and fans. It's also likely that the ERS' efficiency and robustness will decide race results and potentially even the championships, making 2014 the year of energy management in F1.

KERS IN F1 SO FAR

It was as long ago as 2000 when Toyota introduced the first successful hybrid road car. As the environmental lobby has increased, F1 caught up with hybrid technologies with KERS in 2009.

Every time an F1 car accelerates, it burns huge amounts of energy, and as the car brakes this kinetic energy is wasted as heat through the brakes. Energy recovery technologies (ERS) aim to harvest that wasted energy into storage and re-use it to provide a boost of power.

As part of the major 2009 rule changes Kinetic Energy Recovery Systems (KERS) were added into the regulations, although the scope for their use was tightly controlled.

Under braking the energy that would normally be absorbed by the rear brakes was instead harvested by a generator attached to the powertrain. The drag of this generator provided some braking effort and at the same time charged a battery pack.

Then when the driver needed a boost, the power electronics reversed the connections and sent the battery power back to the generator, which then acted as a motor to provide some 80hp for 6.7 seconds. This boost was requested by the driver using a steering wheel button and the dashboard would display the number of seconds of boost remaining.

Drivers were advised how best to use KERS for optimum laptime, usually a small burst of boost out of slow or medium corners. But KERS could also be used as a push-to-pass device or as a defensive tactical tool.

KERS entered F1 in 2009 © XPB

With a glass ceiling of power output the challenge for the engineers under these rules was to make the KERS efficient, reliable and light.

Teams agreed to shelve KERS on cost grounds for a single season in 2010 so it ultimately only had four years of use in its original form. Yet by the end of 2013 the entire battery, motor-generator unit and electronics weighed less than 25kg.

Round trip efficiency was over 80 per cent, which meant that of the power harvested 80 per cent was able to go back into the rear wheels, while reliability was better but still not 100 per cent.

Most teams have had some loss of KERS during qualifying or the race, as the system overheats or other aspects fail. Seeing as KERS was worth 0.3s per lap on average, its loss was a handicap, but not disastrous.

All 11 2013 teams ran KERS, with four different systems in use: Ferrari, Renault, Mercedes and Williams, while Red Bull developed its own battery pack that allowed better packaging but the other components were all supplied through Renault Sport.

Although different in their own right, each system used the same basic layout and in some cases even the same hardware provided by electronics suppliers such as Marelli or battery providers such as Saft and A123.

Universally the motor/generator unit (MGU) was fitted via a gear to the front of the engine's crankshaft. This low and forward placement meant the MGU protruded into the space usually taken up by the fuel tank and a recess needed to be moulded into the back of the monocoque.

Charging as AC current, the MGU power needed to be converted into DC to be stored in the batteries. This task was accomplished by the KERS power controller, three thick cables taking the power from the MGU to the power controller and then another pair to take the power to the battery pack.

Typically the power controller was mounted in the sidepod, its metal case being about the size of a road car's 12v battery.

As well as the power conversion the controller also inverted the power flow from harvesting to discharging, with this being controlled by signals from the FIA standard ECU.

Magneti Marelli KERS components © LAT

Lastly the battery pack was formed by an array of Lithium Ion cells built into a carbon fibre casing, this assembly being about the size of a case of beer cans.

As this was the live electrical part of the system, safety has been the biggest concern with the installation of the battery pack. Most teams fitted the battery pack in a recess under the fuel tank area of the monocoque.

However McLaren placed its version in the right hand sidepod in 2009 and Red Bull famously mounted its astride the gearbox.

With all the high current flowing through the system during charging and discharging the MGU, power controller and batteries all got very hot. While these systems tend to work best when at temperatures above ambient, they equally do not like being run at extreme heat.

Teams would manage the pre-warming and subsequent cooling of the hardware to keep them in the optimum operating temperature. Often in the races it was raised temperatures that forced drivers to cease harvesting or discharging to allow temperature to drop back into the operating window. Water cooling was used for the power electronics and battery, while the MGU tended to be oil cooled.

Although KERS should be hailed as a success and a forerunner of ERS in motorsport, its impact has been limited. The restrictions on power output meant it could never be a full-on technological race for the most powerful system.

Perhaps it was never marketed as it should have been. With Honda and Toyota gone from F1, none of the sport's engine suppliers had a headline road car with hybrid technology.

The fact that the majority of grands prix since 2009 have been won using what is effectively a Prius powertrain remains largely unheralded!

ERS UNDER THE 2014 RULES

This year ERS is being expanded, and far more of the cars' performance will come from hybrid technologies.

To achieve this the FIA has new regulations that lift the limit on kinetic energy recovery and have included another means to harvest wasted energy.

As part of this new world of ERS, a lot of terminology has changed around the engine. We now have a new definition of the 'power unit': this is the internal combustion engine and both types of ERS.

What was KERS is now termed ERS-K (Energy Recovery System - Kinetic), which has twice the power output and five times the energy storage. Then we have the new system ERS-H (Energy Recovery System - Heat), which is another MGU mounted to the engine's turbocharger.

Unlike ERS-K, ERS-H can either deliver what is recovered back into the engine via the ERS-K MGU or spin up the turbo itself via its own MGU. This latter process will reduce turbo lag.

In another change from the KERS installation, the ERS-K MGU will no longer be on the front of the engine, as the unit has doubled in size and due to the new engine packaging rules, the MGU will sit alongside the engine, sited somewhere near the front of the engine and under the exhausts. This will necessitate some repackaging of the water pump, alternator and hydraulic pumps that sat in this area previously.

Conversely the mounting for the ERS-H MGU has to be on the turbocharger itself. So far we have seen two formats where the MGU either sits ahead of the turbocharger (Renault) or in between the two turbines on the turbocharger (Mercedes).

The image released showing this on the Mercedes power unit may not be the actual production solution, and instead it may well install the MGU ahead of the turbocharger as seen on the Renault power unit.

Mercedes' 2014 engine

This places the MGU clear of the hot turbo and underneath the inlet plenum above the power unit.

When the turbo is spinning the MGU will also spin at the same speed, around 100,000rpm, although the MGU-H can run slower if connected by a reduction gear rather than direct from the turbo.

Making the device cope with such speeds and all the associated heat and friction is a huge challenge.

Both MGUs will be connected as before to the power controller and in turn to the 'energy store', which is the new term for the ERS battery.

To cope with the greater through-put of current, both the battery and energy store will need to be bigger than in the days of KERS alone.

This will consume more space in the sidepods and under the fuel tank. Equally all the ERS hardware will require cooling, which will take up far greater volume within the sidepods to house the larger radiators.

These power sources combined will bring the small petrol fuelled engines' output up to the same peak power as the current engines. But as they are electric motors, which produce peak torque from zero revs, they will add a huge amount of low-down torque.

In contrast to the push-button operated KERS, in 2014 drivers can only demand power from the throttle pedal. This leaves the electronics to decide if it is petrol or ERS power that gets sent to the rear wheels. But just as in 2013 the driver will have access to different power maps from the steering wheel, and there will no doubt be a magic button that will give the driver maximum petrol and ERS settings to use tactically during a race.

One unexpected issue with ERS-K is the effect it has on the rear brakes. As the MGU harvests energy it acts like a brake to slow the car. Depending on the harvesting level and the batteries' state of charge, the braking effect can vary.

Teams already tune the harvesting to provide an equal drag on the car throughout the lap, so that when KERS issues occur the driver needs to alter the brake bias to reflect the different braking effect.

In 2014 with the far more complex ERS and greater energy being harvested, braking bias will be hard to manage.

So the FIA has made a bold step and allowed a rear brake-by-wire system for the first time. Described as the 'rear brake control system' in article 11.7 of the technical regulations, this will be a system that reacts to drivers' braking demand at the pedal and applies a corresponding rear braking affect taking into account the ERS harvesting level.

Although a technically an 'active' system, this will not provide any form of anti-lock braking as the control of the system is policed by the FIA standard ECU.

Fans will also face challenges with the new rules © XPB

The system will merely apply the net amount of braking effort the driver puts into the pedal, if the driver pushes too hard, the wheels will lock up.

Of course safety is an issue. The braking effort will be supplied by the car's high pressure hydraulic control systems, and in the event of their failure the normal brake pressure from the rear master cylinder will be diverted to the brakes.

The new ERS-K alone will be able to boost the car for most of the time the driver is on full throttle. As the battery's state of charge (SOC) drops and no energy is left, the ERS-H can provide additional energy to power the ERS-K MGU.

Balancing the use of power and energy will be key in making the most of ERS in qualifying and the race, as well as using the electrical power to offset the reduction in race fuel.

As much as these are very much power unit control systems, it will be as big a job for the teams themselves rather than the engine supplier to understand and write the control code. To this end the larger teams will have greater resources to throw at solving this complex puzzle for each driver at each circuit.

These new systems will be complicated and hard stretched, operating in a tough environment of vibration, heat and load. So it's inevitable that reliability cannot be taken for granted - especially as even the 80hp/6.7s KERS was far from dependable.

And unlike in 2013 an ERS failure could leave the car with just three quarters of its power. This could cost over a second per lap, not to mention the increase in race fuel consumption to offset the loss of ERS.

Failures such as this will be common and will hugely impact drivers' races, potentially even forcing race retirements.

Conversely an efficient ERS can offset fuel consumption. With just 100kg of fuel for the race, relying more on ERS during the race for laptime can reduce the amount of fuel consumed by the engine, allowing a smaller fuel load for a lighter starting weight.

It's hard to imagine that over 160hp will be coming purely from wasted energy. This will be amazing technology and should set F1 on a road to better environmental credentials.

However, much of this technology will hidden away, both the hardware and energy management strategies. Even with TV captions that will show the batteries' state of charge it will be hard to fully understand what a team or driver are doing with the balance of petrol and ERS power in a race.

It will crucial for the teams and engine suppliers to inform the fans about how these technologies are being used if F1 is to maximise the possibilities its bold technical moves have opened.

Next week: Why it's all change for F1 gearboxes in 2014