Control Analysis and Model Validation for BMW i3 Range Extender 2017-01-1152

The control analysis and model validation of a 2014 BMW i3-Range Extender (REX) was conducted based on the test data in this study. The vehicle testing was performed on a chassis dynamometer set within a thermal chamber at the Advanced Powertrain Research Facility at Argonne National Laboratory. The BMW i3-REX is a series-type plug-in hybrid range extended vehicle which consists of a 0.65L in-line 2-cylinder range-extending engine with a 26.6kW generator, 125kW permanent magnet synchronous AC motor, and 18.8kWh lithium-ion battery. Both component and vehicle model including thermal aspects, were developed based on the test data. For example, the engine fuel consumption rate, battery resistance, or cabin HVAC energy consumption are affected by the temperature. Second, the vehicle-level control strategy was analyzed at normal temperature conditions (22°C ambient temperature). The analysis focuses on the engine on/off strategy, battery SOC balancing, and engine operating conditions. Next, we analyze the differences in control strategy based on the environmental conditions (−7°C or 35°C ambient temperatures) or vehicle state (soaked or warmed-up vehicle). Finally, the validation of the developed model based on Autonomie, a high-fidelity, forward-looking vehicle simulation tool, is presented. The engine fuel consumption and battery SOC results are within test-to-test variability in most thermal conditions.