Non-linear control with inherent over-current protection for EV charging unit consisting of single active bridge converter

Active bridge-based chargers for Electric Vehicles (EV) are typically employed in modern power grids in cases where fast, efficient and safe charging conditions are prioritized. Standard control designs for this type of devices usually feature simplistic over-current protection schemes, such as the use of saturation units at the reference current, which are associated with integrator windup and instability phenomena. Contrary to the conventional designs, a novel and model-based Non-Linear Controller (NLC) is proposed for the case of a Single Active Bridge (SAB) fast charger, with a twofold aim: i) to efficiently deliver the desired power to the EV battery through accurate current regulation and ii) to achieve protection of the charging equipment, by inherently limiting the instantaneous converter current below a maximum allowed value without any of the typical drawbacks. This over-current protection property is analytically proved by employing advanced non-linear analysis tools, whereas the stability of the closed-loop system is also guaranteed. The effectiveness of the proposed controller is thoroughly validated on a Typhoon HIL real-time digital simulator by considering different operation cases, including a realistic EV charging scenario (EV charging curve).