Tuning rules for passivity-preserving controllers

Nonlinear passivity-based control (PBC) algorithms for power converters have proven to be an interesting alternative for other, mostly linear, control techniques. The control objective is usually achieved through an energy reshaping process and by injecting damping to modify the dissipation structure of the system. However, a key question that arises during the implementation of the controller is how to tune the various parameters. From previous work we know that a PBC controller forces the closed-loop dynamics to behave as if there are artificial resistors connected to the real circuit elements. This has led to conservative tuning rules stemming from characteristic impedance matching conditions. In this paper an alternative solution is provided that uses the classical Brayton-Moser equations (1964). The criteria derived from these equations result in fairly sharp and less conservative tuning rules to guarantee stability and non-oscillatory responses. Both criteria are compared and tested using the elementary single-switch boost converter.