US Patent 9257864 Input power controller for AC/DC battery charging

A control approach of adjusting the input power of a power factor correction (PFC) stage so that the output voltage (DC-link) of the input AC/DC stage to an intermediate DC voltage (DC-Bus voltage) is adjusted based on the amount of power required to charge a high energy battery is disclosed. The present invention controls the input power of the PFC instead of the DC-bus voltage as is common in conventional methods. Therefore, a very fast response compared to the conventional sluggish voltage loop can be achieved. Also, having different DC-bus voltages for different output load conditions allows the DC/DC converter to work with an optimal duty cycle for a whole range of load variations.