An Optimal Control Method for Buck ConvertersUsing a Practical Capacitor ChargeBalance Technique

A novel control method is presented in this paper which utilizes the concept of capacitor charge balance to achieve optimal dynamic response for buck converters undergoing a rapid load change. The proposed charge balance method is implemented with analog components and is cheaper and more effective than its digital counterparts since complex arithmetic and sampling delay is eliminated. The proposed controller will consistently cause the buck converter to recover from an arbitrary load transient with the smallest possible voltage deviation in the shortest possible settling time. Since the controller is nonlinear during transient conditions, it is not limited by bandwidth/switching frequency. Unlike conventional linear controllers, the dynamic response (voltage deviation, settling time) of the proposed controller can be estimated using a set of equations. This greatly simplifies the design process of the output filter. Simulation and experimental results show the functionality of the controller and demonstrate the superior dynamic response over that of a conventional linear controller.