Estimation and compensation of DC-Link voltage disturbances in a DC-DC converter for battery emulation

Battery emulation is essential for reliable testing of powertrains of electric and hybrid vehicles under repeatable conditions. For that purpose, a DC voltage controller provides fast reference tracking capabilities. Due to imperfect conversion of AC current to DC current, the DC voltage source of the battery emulator does not provide constant voltage but is subject to periodic fluctuations. This disturbance is propagated through the system to the battery emulator's output. In this paper, an observer-based compensation strategy is deployed. As the structure of the multiplicative perturbation is known, it is integrated into the battery emulator model yielding a state-affine system. An appropriate observer provides asymptotically correct estimates of the disturbance, which are then used to adequately manipulate the control variable without interfering with stability properties of the closed-loop system. Simulation and experimental results show the improvements achieved by the disturbance rejection.