TU/e introduces converted VW Lupo electric research vehicle; lightweight and longer range

The donor Lupo, the old diesel powertrain, and the new electric powertrain. Click to enlarge.

Over the past year the Dynamics and Control group of the Eindhoven University of Technology (TU/e) (The Netherlands) has developed a battery electric research vehicle based on a VW Lupo 3L 1.2 TDI. The vehicle, formally launched this week, will be on display at AutoRAI in Amsterdam, 13-23 April.

The Lupo EL (“Electric Lightweight”)vehicle combines a very low weight (1,060 kg, 2,337 lbs) with a large battery pack (27 kWh). This results in a range increase of 30% to 50% in comparison to existing electric vehicles with four seats on the market today— 215 km (134 miles) urban and 135 km (84 miles) highway on the Artemis cycle. Despite the presence of a large battery, the interior and cargo space dimensions remain unchanged.

Electric vehicle system diagram. Source: TU/e. Click to enlarge.

The 4-seat Lupo EL has a top speed of 130 km/h (81 mph) and accelerates from 0 – 100 km/h in 12 seconds.

The Thundersky batteries use a lithium iron phosphate (LiFePO₄) chemistry, which has a comparatively low cost of less than €300/kWh (US$434/kWh), is considered safe and has a long cycle life. The disadvantage is somewhat reduced energy density compared other Li-ion chemistries.

Under the hoods of the Lupo TDI and Lupo EL. Click to enlarge.

The vehicle is approved by the Dutch roadworthiness authorities (RDW) and is allowed to drive on the public road. The vehicle is developed for research purposes and includes various sensors to monitor the batteries, power train, energy consumption of components and vehicle dynamics. Furthermore, the vehicle is equipped with a central controller (PLC), which controls 4 CAN busses and 80 I/O ports. This results in a very flexible, programmable environment allowing different types of research to be executed. Additionally the existing VW systems, including ABS, airbags and dashboard are fully functional.

Various research topics have been and are being addressed, including:

• vehicle performance analysis, range estimation and battery sizing;
• efficient heating of the vehicle interior;
• component testing and modelling, e.g. battery efficiency;
• analysis of regenerative braking strategies;
• full vehicle modelling using multi-body software tools;
• investigation of the benefits of in-wheel motors;
• vehicle control software development;
• development of a user interface to inform the driver on the vehicle status; and
• electric power steering.

Power train components include:

• Charger: Brusa NLG 513 WC, charging power 3.3 kW, 260 - 520 V DC out, programmable, water cooled, CAN

• Charging plug: Mennekes 31013, VDE-AR-E 2623-2-2

• Li-ion batteries: Winston Battery/Thunder Sky TS-LFP90AHA, capacity 90 Ah, 3.3V, cycle life > 2000 @ 80% DOD, chemistry: LiFePO4, 91 cells in series, 273 kg, 27 kWh

• BMS: Elithion Lithiumate, measurement of cell voltage, temperature and internal resistance, passive balancing, max. balancing current 200 mA, CAN

• Inverter: MES-DEA TIM 600W, max. current 236 A (nominal), 400 A (peak), 80 - 400 V DC in, switching frequency 3-9 kHz, water cooled, CAN

• Motor: MES-DEA A200-200, 24 kW/80 N·m (nominal), 50 kW/270 N·m (peak), AC induction, 10500 rpm max., water cooled

• Reduction: Carraro 150009, single gear fixed reduction, ratio 8.654:1

• DC-DC converter: MES-DEA 400-1000 150 - 400 V DC in, 13.3 - 14.4 V DC out, max. power 1000 W, max. current 70 A, air cooled

• PLC: IFM CR0232, 32-bit CPU Infineon TriCore 1796, 80 IO ports, 4x CAN

Range and energy usage. Click to enlarge.

Source: Green Car Congress