Digital control of a 1 kW battery charger with a single IGBT switch in the grid

Commercial high-power battery chargers usually use controlled rectifiers with SCR semiconductors and phase control in the secondary winding of a transformer connected to the supply grid. Generally, currents handled by these semiconductors are very high, while the voltages are usually far below the nominal voltage of the electrical network. This paper proposes a battery charger with digital control of the charging current and which operates at the grid voltage level at low current. It can be implemented using a single IGBT switch. The system is controlled by a microcontroller that incorporates the technique of firing by pulse width modulation (PWM) controlled by a PID digital regulator with control of the charge current.