Resilient Control Design for EV Fast Charging Unit Consisting of Multiple SAB Converter Modules

An electric vehicle (EV) fast charging unit usually consists of multiple modules connected in parallel to share the total current among them and achieve high power ratings. In this article, a charging unit with multiple parallel single active bridge (SAB) converter modules is considered and a novel nonlinear resilient controller (NLRC) is proposed to achieve all of the following properties: 1) accurate current sharing among multiple SAB modules during normal operation; 2) inherently limit the instantaneous current of each module within a given range at all times; 3) rigorously guarantee closed-loop system stability; and 4) enhance the charging unit resilience under abnormal operation (e.g., module set-point attack and sensor/measurement fault). Using nonlinear analysis and invariant set theory, the boundedness of the instantaneous current for each SAB module is rigorously proved. Furthermore, closed-loop system stability is analytically shown based on matrix properties independently of the charging unit or controller parameters, opposed to conventional root-locus analysis that relies on a specific set of system parameters. Moreover, the resilience property of the novel NLRC is analytically articulated in the case where one or more modules are compromised due to set-point attack or sensor/communication failures. The effectiveness of the proposed controller is demonstrated against the state-of-the-art control structures using both simulation and a suitable experimental testbed for both normal and abnormal scenarios, including an experimental implementation of an entire charging session (typical EV battery charging curve).