Boundary-Based Hybrid Control Algorithm for Switched Boost Converter Operating in CCM and DCM

Abstract

It is essential to have enhanced efficiency for the DC-DC converters operating in continuous conduction mode (CCM) and discontinuous conduction mode (DCM). This requires a hybrid controller designed using pulse width modulation (PWM) and pulse frequency modulation (PFM) schemes. This paper fixates on a boundary-based hybrid control algorithm for the second-order DC-DC converter - the switched boost converter. The proposed algorithm works in PWM control scheme for CCM operation, whereas DCM operation uses PFM control scheme. The boundary conditions are defined by the load current, output voltage, and switching frequency. Here, an attempt is carried out to have the advantages of both the control schemes. The boost converter is represented by the switched system operating in three modes. Violating transition guards condition orchestrates the switching among these modes. A supervisor detects the CCM and DCM operations, and subsequently switches between PWM and PFM control scheme. Extensive circuit-level simulations are carried out in MATLAB to show the efficacy of the suggested algorithm under the fluctuating line, load, and set-point.