Generalized Hybrid Feedforward Control of Pulse Width Modulated Switching Converters

This paper presents general considerations for synthesis of hybrid feedforward control architectures for pulsewidth modulated (PWM) switching converters, where selected converter variables are sensed and utilized to determine the duty cycle to achieve a control objective based on the converter open-loop characteristics. Compared to standard feedback control techniques, advantages may include simpler controller implementation, more convenient sensing, and improved static and dynamic regulation. The approach is illustrated first through previously known examples, including feedforward control of boost PWM converters operating in continuous conduction mode (CCM), and hybrid feedforward control of boost power factor correction (PFC) rectifiers operating in discontinuous conduction mode (DCM). The synthesis principles are then used to realize new hybrid feedforward control architectures for a battery charger application, which comprises a four-switch non-inverting buckboost converter to implement PFC functionality, followed by a buck converter to regulate battery charging power. Experimental results are provided for the considered hybrid feedforward controlled converters.