Average Natural Trajectories (ANTs) for buck converters: Centric-based control

This paper introduces the concept of Average Natural Trajectories (ANTs) for buck converters to produce a centric-based PWM control strategy. Mathematical expressions that describe the average paths the converter operating point follows are found by employing averaging in the geometrical domain. Based on the obtained trajectories, a novel type of robust, fixed switching frequency control technique is developed. The characteristic features of the technique are fast and predictable transient response, low computational burden, and low bandwidth for the sensors with fixed frequency operation. Operation in open loop validates the ANTs trajectories and establishes the foundation of the proposed control equations. Closed loop operation is obtained by performing the control algorithm calculation to obtain the centric PWM duty cycle. As a result, the converter operating point is directed towards the target following the ANT, and only one centric PWM duty cycle calculation is required. The implementation of the centric-based PWM control is suitable for low cost microcontrollers as well as low bandwidth sensing systems, which combined with the mentioned enhanced dynamical performance, turns the controller into a very appealing option for high volume production applications.