A duty cycle controller apparatus for producing a duty cycle signal for controlling switching of switches of a battery charger having an AC input for receiving power and an output for supplying power to charge a battery in response to switching of the switches, while maintaining a high power factor at the AC input. The duty cycle controller apparatus includes a current command signal generator having a plurality of signal inputs for receiving a plurality of signals representing a plurality of operating conditions of the charger, a plurality of current command outputs and a processor operably configured to generate a plurality of current command signals at the current command outputs in response to respective sets of operating conditions.