Control Strategy for a Dedicated On-Board Isolated Battery Charger

This paper presents the design and modeling of a controller applied to a battery charger. The battery charger topology is composed of two stages: the Power Factor Compensation stage and the isolated DC-DC power supply. The first one consists of a boost-rectifier stage connected to the grid and is based on Full-bridge topology; the second stage is an isolated DC-DC power supply associated with the battery charging. The last is composed of three main components, an inverter that generates high-frequency AC to induce a magnetic field of a transformer; the transformer provides galvanic isolation to the battery side, and a bridge rectifier connected to the batteries. Both stages are linked by a capacitor which in turn acts as the output of the PFC boost-rectifier stage and behaves as a constant input source to the DC conversion stage. Thus, the proposed control law consists of three main loops. The current control loop aims to guarantee a power factor close to the unity. The DC voltage mode control loop is intended to regulate the DC capacitor voltage. And, the battery charging control loop is intended to assure proper battery charging. For the last, the constant-current and constant-voltage charging profiles are considered. Besides, adaptive estimators are considered to deal with parametric uncertainties of the input impedance. Finally, numerical results are obtained to evaluate the proposed control law.