Dual current-mode control for single-switch two-output switching power converters

A novel method for programming current in DC/DC converters operating in discontinuous conduction mode is described in this paper. The control variable is the product of the square of the duty cycle and the switching period, i.e., D²T, which is directly proportional to input and output currents of a discontinuous-mode converter. A method of controlling D²T is applied to converters that utilize one switch (or one set of synchronous switches) for achieving two control functions. In particular a single-switch two-output boost converter, in which a continuous-mode converter and a discontinuous-mode converter share one active switch, is studied. In this system, current-mode control is used to regulate the output voltage of the continuous-mode converter and the proposed D²T control is used to regulate the other discontinuous-mode converter. The result is a generic current-mode controlled dual-output converter.