Study into Kinetic Energy Recovery Systems Optimisation

Transcription

1 Study into Kinetic Energy Recovery Systems Optimisation. Automotive Council Energy Storage Group Phillip Taylor CEng FIMechE, Millbrook Proving Ground Millbrook Proving Ground Limited

2 Millbrook Group Overview Millbrook Group is made up of Millbrook Proving Ground in the UK and Test World in Finnish Lapland. It is a leading European provider of vehicle testing, engineering and conversion services. Millbrook Proving Ground Limited

3 Background Automotive Council UK set up its Energy Storage Group: Context : Temporary storage of recoverable kinetic energy in the vehicle with the aim of improving vehicle efficiency => improved fuel economy and CO 2 emissions. Brief: Define roadmap for energy storage technologies. Preparatory Study Subject of this presentation: Establish optimised power and energy requirements for vehicle KERS. Wide range of vehicle types, approximate to real world as far as possible. Literature Review: No previous work found replicating the proposed study. Some data helpful for validation and sense checks. Millbrook Proving Ground Limited

4 Vehicles, Masses & Drive Cycles Vehicle types, masses including payloads defined: Scope : L class light vehicle to fully laden 40 Tonne lorry, plus fork lift truck. Vehicle masses and other parameters, e.g. frontal area, C d etc. established. Typical payloads derived from official sources or estimated. Drive cycle selection: Greater range of drive cycles => closer approximation to real world. Cycles matched to vehicle types, see matrix next slide. Millbrook Proving Ground Limited

5 Vehicles, Masses & Drive Cycles Vehicle / Drive cycle matrix: Green cells indicate combinations assessed. Millbrook Proving Ground Limited

6 Vehicles, Masses & Drive Cycles Drive cycle analysis: Typical example input data : (Example: Artemis Road / Family Saloon) Millbrook Proving Ground Limited

7 Vehicles, Masses & Drive Cycles Drive cycle analysis: Second by second speed data for each cycle plotted in Excel. Power and energy (driving and braking) calculated from first principles: Validated using Torotrak s proprietary simulation tool and by comparison with real vehicle test data. Millbrook Proving Ground Limited

8 Vehicles, Masses & Drive Cycles Drive cycle analysis: Power and energy calculated for all the selected vehicle / cycle combinations: At the wheels, therefore independent of drive train characteristics. Net of aerodynamic and rolling losses. Hotel loads / parasitic losses accounted for later. (Example: Artemis Road / Family Saloon) Millbrook Proving Ground Limited

9 Recoverable Kinetic Energy Defined as the deceleration energy net of losses, equivalent to the energy dissipated in the brakes: Note numbers appear high because parasitic losses not accounted for (yet) Millbrook Proving Ground Limited

10 Recoverable Kinetic Energy But, how to interpret the data to give useful information for KERS sizing (energy and power)? Energy used and recoverable can be plotted: (Example: Artemis 130 cycle) And cumulative: Millbrook Proving Ground Limited

11 Recoverable Kinetic Energy Analysis so far had not given any useful parameters to allow a KERS to be specified. The breakthrough Events method: Event defined as a discrete section of the drive cycle where the acceleration or deceleration is constant. Each cycle studied as a series of acceleration and deceleration events. Focus placed on deceleration events using the friction brakes (i.e. net of losses). This gives the recoverable energy and the power needed to capture it this is important. Millbrook Proving Ground Limited

12 Recoverable Kinetic Energy Plotting individual events, power and energy: (Example: Hatchback M1, Artemis Road) N.B. Regeneration is positive Millbrook Proving Ground Limited

13 Recoverable Kinetic Energy Ranking regeneration events by power and energy: (Example: Hatchback M1) Millbrook Proving Ground Limited

14 Recoverable Kinetic Energy Summarise all the regeneration events of all the cycles: (Power) Millbrook Proving Ground Limited

15 Recoverable Kinetic Energy Summarise all the regeneration events of all the cycles: (Energy) Millbrook Proving Ground Limited

16 Recoverable Kinetic Energy Plot energy vs power: Millbrook Proving Ground Limited

17 Recoverable Kinetic Energy Plot energy vs power a KERS size estimation is now possible: Millbrook Proving Ground Limited

18 Optimisation of KERS size Analysis so far discussed is At the Wheels and does not include parasitic losses, hotel loads, engine braking effects etc. Additional consideration is consecutive events: Therefore more sophisticated simulations were carried out, taking these factors into account. (N.B. NEDC removed at this stage : outlier & obsolete) Millbrook Proving Ground Limited

19 Optimisation of KERS size Hotel loads, parasitic losses and engine off savings now included. Event energy and event power allows specification of a theoretical KERS. Using 3D parametric plotting technique, optimised to exclude outlier events and cycles. Clear cut-off at around 92.5% of recovered energy (diminishing returns). Millbrook Proving Ground Limited

20 Optimisation of KERS size Optimised theoretical KERS values for each vehicle type shown here: N.B. BAU = Business As Usual = without engine-off coasting capability Millbrook Proving Ground Limited

21 Optimisation of KERS size Graphical representation: Interestingly, the power / energy ratio is similar for all vehicle types. 1.7kWh Millbrook Proving Ground Limited

22 Optimisation of KERS size Zooming in to the light vehicles only: 0.06kWh Millbrook Proving Ground Limited

23 Conclusions Group has created a technique to assess multiple drive cycles for a single vehicle type in order to approximate to real world conditions. The technique has been applied to multiple vehicle types. The energy storage size to recover over 90% of recoverable kinetic energy is relatively small: but high power and low energy. Data available to Energy Storage Group to inform KERS roadmap => specify appropriate technologies and capacities for various vehicle types. Millbrook Proving Ground Limited

24 Thank you Millbrook Proving Ground Limited