Analysis and synthesis of reconfigurable digital pulse train control in a DCM buck converter

Pulse train (PT) control improves light load efficiency of a dc-dc converter by use of high and low pulses with different frequencies. This bi-frequency operation spreads the spectrum over discrete frequencies and helps in reducing effects due to EMI. This paper proposes a reconfigurable digital PT control technique in a DCM buck converter. This enables to online configure time periods and/or widths of both high and low pulses. This can take forms of a variety of light load control techniques. Discrete-time models are derived, which take the form of 1-D discontinuous maps. Thereafter, nonlinear analysis is carried out. This allows to accurately investigate dynamics of a buck converter under PT control and also provides design guidelines for achieving improved spectrum and efficiency. The proposed control method is simple to implement and requires less hardware resources compared to existing schemes. A buck converter prototype is tested, and the proposed method is implemented using an FPGA device. The analytical framework helps in analyzing existing light load control methods.