2014: A new energy management challenge for F1

‘‘There are two sources of energy to propel the car; fuel in the tank and electrical energy in the energy store, or battery. The use of the two types of energy needs an intelligent management, since the permissible fuel consumption in the race is limited to 100kg and the battery needs recharging to avoid it going flat,’’ Renault technical director for new generation Power Units, Naoki Tokunaga, explains.

‘‘For 2014, the fuel flow is limited to 100 kg/hr, and the fuel quantity for the race to 100kg. So if the car uses fuel at the maximum permitted rate of 100 kg/hr, it can do so for only 1 hour. The car performance is intended to be similar to 2013, so in fact the races will last more like 1hr 30min. Of course the circuit and car characteristics will not allow the cars to run at maximum power all around the lap. On all circuits, it is predicted that the natural fuel consumption for the race distance will be close to the allowed 100kg, in some case just under, in some cases just over. If just over, then it will be necessary to decide how to use the available fuel.

‘‘The F1 cars for 2014 may be categorised as a hybrid electric vehicle (HEV), which combines a conventional internal combustion engine with an electric propulsion system, rather than a full electric vehicle (EV). Like road-going HEVs, the battery in the F1 cars is relatively small sized. The relevant technical regulations mean that if the battery discharged the maximum permitted energy around the lap, the battery would go flat just after a couple of laps. In order to maintain “state of charge” (SOC) of the battery, electrical energy management will be just as important as fuel management.

‘‘The energy management system ostensibly decides when and how much fuel to take out of the tank and when and how much energy to take out or put back in to the battery.

‘‘The overall objective is to minimize the time going round a lap of the circuit for a given energy budget. This might sound nothing like road-relevant, but essentially, this is the same problem as the road cars: minimizing fuel consumption for a given travel in a given time – the input and output are just the other way around.

‘‘The question then becomes where to deploy the energy in the lap. This season, KERS is used only a few places in a lap. But from 2014 all of the energy, from fuel and battery, is so precious that we will have to identify where deployment of the energy will be beneficial over the whole lap and saving will be least harmful for lap time – we call it “power scheduling”. This will be decided jointly between the chassis teams’ vehicle dynamics departments and Renault Sport F1 in Viry-Châtillon.

‘‘Choosing the best split between the fuel-injected engine and electric motor to get the power out of the Power Unit will come down to where operation of these components is most efficient. But again, SOC management presents a constraint to the usage of the electric propulsion. And the optimum solution will vary vastly from circuit to circuit, dependent on factors including percentage of wide open throttle, cornering speeds and aerodynamic configuration of the car.

‘‘There are quite a few components which will be directly or indirectly controlled by the energy management system; namely the internal combustion engine, the turbo, the ERS-K, ERS-H, battery and then the braking system. Each has their own requirement at any given time, for example the operating temperature limit. There can also be many different energy paths between those components. As a result, the control algorithm can be quite complex to develop and manage.

‘‘What is clear, however, is that at any given time, as much energy as possible, which would otherwise be wasted, will be recovered and put back into the car system. It would not be an over-estimation to state that the F1 cars of next year are probably the most fuel and energy efficient machines on the road.’’