The NiMH pack in the ISG hybrid is packaged behind the rear seats with minimal intrusion into the luggage compartment. Click to enlarge.

Chery is sourcing NiMH battery packs for its ISG hybrid from Johnson Controls-Saft. (Earlier post.)

Key Ricardo responsibilities for the BSG program included:

• Full architecture, sub-system and components requirements definition;

• Hybrid control unit design;

• Vehicle and communications interface development;

• System design including detailed thermal analysis;

• Powertrain control strategy for safety and efficient operation.

The first prototype vehicle was run with production-intent hardware, complete with hybrid strategy and application software, just ten months from the start of the project. In tests on the ECE Urban drive cycle, the BSG vehicle achieved approximately 7% improvement in fuel consumption over the baseline product. Improvements of greater than 10% are expected in real-world urban driving.

For the more complex ISG product, Ricardo assumed full system design responsibility, including specification and integration of the ISG system and the high-voltage battery pack and battery management system. Ricardo also developed an integrated hybrid control unit that incorporates the motor drive power electronics, DC to DC converter, and hybrid supervisory and safety functions into one compact package. The safety-critical application strategies and software were defined, engineered and validated through extensive vehicle and hardware-in-the-loop testing.

With its mild-hybrid functionality, the ISG-equipped sedan provides a significant increase in performance over the equivalent baseline A5 vehicle with a 1.3 liter engine. Peak power and torque of the ISG-equipped vehicle are comparable to a 1.6-liter engine. Final production calibration and testing of the vehicle systems are still taking place, but the fuel consumption improvement over the NEDC cycle is expected to approach 15% compared to the 1.6-liter benchmark vehicle. In addition, the system enables engine restart within 200 milliseconds, thus allowing stop-start functionality to be included in the hybrid control strategy.

Engineered to exacting European emissions requirements, these new vehicles are due to enter full production shortly and will be available for both domestic Chinese and export markets.