Selection of High Efficiency Motors for Vehicle Powertrains Dr Will Drury

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1 Energy Efficient Motors Selection of High Efficiency Motors for Vehicle Powertrains Dr Will Drury 12 th March 2014 Energy Efficient Motors Workshop Solutions for the Next Generation What we do from strategy definition to production Strategy & Advice Design & Analysis Product Development & Test Product Launch Production & Compliance 2 1

2 Energy Efficient Motors Who we work with Passenger Car High Performance Vehicles & Motorsport Commercial Vehicles Motorcycles & Personal Transportation Agricultural & Industrial Vehicles Government & Environment Rail Defence Clean Energy & Power Generation Marine TACOM UK MoD 3 Why do we need Hybrid & Electric Vehicles?? 4 2

3 Energy Efficient Motors Hybrid Configurations: Key to sub-systems Engine Management System (EMS) EMS Transmission Control Unit (TCU) Hybrid Control Unit (HCU) 12V Battery DC/DC Converter Belt Starter Generator (BSG) Engine 12V Starter Motor TCU HCU Electric Machine Torque Converter with Lockup Clutch Epicyclic gear (powersplit device) Inverter Clutch Gearbox Transfer Case Differential High Voltage (HV) Battery 5 There is a very wide range of rotating and linear drives and actuators in vehicles and the requirements differs widely between different power levels and applications Engines Transmissions Vehicle & Hybrid Systems Marine Clean Energy & Power Generation Rail High Performance & Motorsport 1W 10W 100W 1kW 10kW 100kW 1MW Starter / alternator Actuation & pumps Small ancillaries Small ancillaries Small ancillaries Mild & Full hybrid car Domestic small scale Full & performance hybrid car Commercial Scale Pumps, ancillaries Hybridisation / KERS & actuation Propulsion Traction Requirements capture is the key activity in selection the correct emachine for each application LGV hybridisation Industrial scale Vehicles, that on the surface are the same, will have different transmission types (AMT, DCT ), gear ratios and performance requirements Rating emachines for peak performance is a common pitfall and often leads to oversizing therefore increasing weight and cost For example McLaren P1 emachine produces 131kW (176bhp) of power that more akin to an EV approach. The peak vs continuous rating of this machine is high to fill engine torque gaps during gear shifts when accelerating 0-100km/h (62mph) in 2.8s 6 3

4 Energy Efficient Motors Introducing emachines There is a wide variety of candidate electric machine topologies Induction motor: Torque speed curve with inverter control IPM motor: Performance trends against load Drive selection Different types & designs of emachine & controller are suitable for different applications, but it can be difficult to choose the best There are also many ways of mounting, gearing & controlling them Selection of the most appropriate machine & the best mounting requires good knowledge of the application through specifications & experience, as well as knowledge of quantities, manufacturing and material costs Synchrel motor: Torque-speedefficiency map 260 Nm 110 6:4 SR Motor: Torque ripple variation by stator & rotor pole widths Selection process The requirements of the application can be found and mapped as a torque speed efficiency map Then the edrive system can be specified & various different designs assessed using different motor types, pole counts, power circuit topologies etc. Alternative mounts & gear ratios can be modelled Ricardo s engineers have experience of many applications, many markets, & most technologies 7 Peak efficiency of a selected machine is not the best performance indicator Power vs time for D-segment car over WLTP drive cycle Time (s) Power (W) 8 4

5 Energy Efficient Motors Conclusions Hybrid and electric vehicles are here to stay due to both legislation and reducing natural resources Electrical machines and drive systems are key to the success of this industry There are such a variety of application of emachines in automotive, no single solution is the right answer The foreseen demise of the PM machine is over as magnet costs have stabilised over recent months & years however, research is strong in non-pm machines such as SR The use of PM material is however still under consideration due to potential volatility in the market price The selection of the machine type needs to reflect the drive cycle performance not (just) peak performance 9 Parting thought To get more hybrid & electric vehicles on the road, the biggest hurdle to overcome of the electrical powertrain, regardless of machine type, is COST

6 Energy Efficient Motors Any questions Ricardo UK Ltd Cambridge Technical Centre, 400 Science Park, Milton Road Cambridge, CB4 0WH, UK Dr Will Drury Senior Engineer Electric Drives Direct Dial: +44 (0) Reception: +44 (0) Mobile: +44 (0)