A Model-Based Controller for an Isolated Inverter for Electric Vehicle Applications

This paper proposes a model-based controller for a state-of-the-art isolated inverter, with the aim to provide a low THD true-sine wave (TSW) single-phase voltage to feed auxiliary loads in EV applications, which is a requirement of great relevance in the current market. The studied topology comprises two stages, namely an isolated DC-DC converter, and a TSW inverter. Isolation in the first stage is provided by means of a high-frequency transformer fed by an H-bridge converter, which creates a high-frequency switching alternating signal out of the EV DC-bus voltage. The transformer output is processed by a full-bridge rectifier and a filter to create a regulated DC voltage signal. In the second stage, an H-bridge converter followed by a second-order filter creates a TSW by inverting the regulated DC output of the DC-DC converter. The proposed controller comprises a proportional-integral-derivative (PID) solution to regulate the DC output voltage of the DC-DC isolated converter; and a proportional-resonant (PR) solution to guarantee a TSW output voltage with low THD in spite of the presence of non-linear distorting loads. In particular, the PR controller involves the measurement of the output capacitor current to incorporate additional damping. Simulation results are presented to assess the performance of the proposed control algorithms.