Battery impedance emulation for hybrid and electric powertrain testing

With battery emulators, development engineers can test electrical drives on testbeds without the need for costly battery prototypes. Furthermore, valuable time for battery pre-conditioning can be saved. However, high quality battery emulation is a challenge that requires a good battery model and accurate emulation of the model with a controllable power supply. A high-fidelity nonlinear battery model based on local model networks is used. This allows the extraction of local linear models for impedance emulation with a switch model DC-DC converter. Local linear battery models and a model of the converter are combined to a prediction model which is used for designing a model predictive controller. In contrast to existing impedance emulation schemes with cascaded feedback loops, the virtual impedance is included in the inner voltage control loop in order to achieve the highest possible bandwidth. Owing to constrained optimal control, this is achieved while respecting control variable constraints and inductor current safety limits. Experimental results show the effectiveness of the proposed battery impedance emulation scheme.